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EPE 2002-07 - Parent Directory

1. Miscellaneous T1 mains transformer see text and Table 1 FS1 1A 20mm slow blow fuse to suit holder PL1 Euro fused mains inlet chassis mounting plug with line socket Printed circuit board available from the EPE PCB Service code 356 PSU metal case size and type to choice multistrand connecting wire mains cable aluminium sheet or proprietary heatsink and heatsink compound solder pins nuts bolts and washers stand off pillars 4 off solder etc Approx Cost 20 Guidance Only excluding case REGULATED V SEPARATE EARTH OV RAIL RETURNS TO PREAMP POWER AMP ETC REGULATED V ees 3 4IN 86 4mm S TYPE 1 85IN 47mm lt IC1 AND IC2 NUMBER CONNECTION DETAILS Vink lee 1 2 3 COMMON Fig 2 Power Supply printed circuit board full size copper master and suggested mains transformer and separate panel fuseholder interwiring The 16 s w g aluminium heatsink measures 45mm x 45mm 502 Everyday Practical Electronics July 2002 followed by the larger electrolytic types and the voltage regulators IC1 and IC2 Finally you will need to bolt a heatsink to the regu lators and details of choosing a suitable heatsink will be given shortly Solder pins inserted at the lead out points simplify the task of off board wiring Diodes D1 to D4 the reservoir capaci tor C5 and the regulators IC1 and IC2 have to be chosen to suit the voltage and current to be delivered by the power sup
2. BOOK ORDER FORM Full NAME ccscscdsciceciccdstencccsaidesoedesdedasesnanasvessacaeeccdensed Address aoe catiece tired accncdunesckuncusineaeusdaesenccducdevaveusexenedecs Post code 8 10 gt eee eee er reer PSE en Se a Spent e ears es een Telephone NO sctsccwcescecdinssaenccdaccccceaScdtenseeened L_ enclose cheque PO payable to DIRECT BOOK SERVICE for C_ Please charge my card Card Number Please continue on separate sheet of paper if necessary If you do not wish to cut your magazine send a letter or copy of this form Everyday Practical Electronics July 2002 PROJECT TITLE Camcorder Power Supply OCT 01 318 5 94 PIC Toolkit Mk3 319 8 24 Perpetual Projects Uniboard 4 Gate Sentinel Solar 305 3 00 powered Bird Scarer and Solar Powered Register 320 4 28 Teach In 2002 Power Supply Lights Needed Alert Printed circuit boards for most recent EPE constructional projects are available from Pitch Switch the PCB Service see list These are fabricated in glass fibre and are fully drilled and Capacitance Meter Main Board double sided roller tinned All prices include VAT and postage and packing Add 1 per board for Display Board double sided airmail outside of Europe Remittances should be sent to The PCB Service A amp PIC Toolkit TK3 Software onl Everyday Practical Electronics Wimborne Publishing Ltd 408 Wimborne Road 4 Ch T Twinklina
3. HUME jame ever tecees kez eves ans ee ees ech rs es een ee es ee es eA ew ews I Gob Ged ose ak oh eee a oe alee Bale POS COUG o pasire cate ntt is Tel No l l l C enclose cheque PO in sterling payable to WIMBORNE PUBLISHING LTD for J Please charge my Visa Mastercard Amex Diners Club Switch Card expiry date I ORDERING ALL PRICES INCLUDE UK POSTAGE Student Single User Standard Version price includes postage to most countries in the world EU residents outside the UK add 5 for airmail postage per order ee50b SURFING THE INTERNET NET WORK ALAN WINSTANLEY A Fistful of Dollars Wr to Net Work our column written for Internet users As regular readers will know ever since its beta days Google www google com has been my preferred search engine for hunt ing down elusive information on the Internet It is a pure search engine that runs on a whole farm of computers and it returns results almost instantaneously Compare this with Yahoo www yahoo com one of the world s most popular directories while Google searches the Internet Yahoo searches its own database of web sites instead which it has organised in a highly structured manner The same is true of the popular Open Directory Project the largest human edited directory on the web at www dmoz org Web sites are included in the Yahoo directory only with the permission of Yahoo editors and it s
4. Please supply me Vann Draper is offering over 20 discount to readers of Everyday Practical Electronics on their new range of low cost digimess power supplies Qty Stes Model ces c iets eaten Pace see eeu QUY cena MOCO sipeer PHICE doicenwearenens The range includes single dual triple and high current output types All feature LED displays of voltage and current and can be operated in constant voltage or constant Name current modes Dual and triple types have switching for independent series parallel and tracking modes All models are supplied complete with mains lead operating manual Address and a 1 year guarantee Model number HY3003 HY3003 2 HY3003 3 HY3010 HY3020 seine Price inc vat amp del 99 00 169 00 199 00 275 00 375 00 2 F s Total He ON Uo amele Dual wpe single Sale Cheques payable to Vann Draper Electronics Ltd Output voltage 0 30V 2 x 0 30V 2 x 0 30V 5V 0 30V 0 30V or debit my visa mastercard or switch card Output current 0 3A 2 x 0 3A 2 x 0 3A 3A 0 10A 0 20A Card type Load regulation lt 0 01 lt 0 01 lt 0 01 lt 0 02 lt 0 02 Card No Ripple amp noise lt 1mV rms lt 1mV rms lt 1mV rms lt 3mV rms lt 3mV rms Excinndate Safin issus Nia Dimensions mm 291x158x136 365x265x164 365x265x164 365x265x164 365x265x164 Signature To order simply post the coupon to Vann Draper Electronics Ltd Stenson House Stenson Derby DE73 1HL Or Tel 01283 704706 Fax 01283 7047
5. APR 02 PROJECTS e Electric Guitar Tuner e PIC Controlled Intruder Alarm Solar Charge and Go e Manual Stepper Motor Controller FEATURES e Teach In 2002 Part 6 Interface e Programming PIC Interrupts 2 Circuit Surgery e Ingenuity Unlimited New Technology Update Net Work The Internet Page FREE Giant Op Amp Data Chart MAY 02 PROJECTS e PIC Big Digit Display Simple Audio Circuits 1 Freezer Alarm Washing Ready Indicator FEATURES e Teach In 2002 Part 7 Ingenuity Unlimited Practically Speaking New Technology Update e Circuit Surgery Net Work The Internet Page JUNE 02 PROJECTS Biopic Heartbeat Monitor Frequency Standard Generator Simple Audio Circuits 2 World Lamp FEATURES e Teach In 2002 Part 8 Interface New Technology Update e Circuit Surgery Ingenuity Unlimited Net Work The Internet Page BACK ISSUES ONLY 3 30 each inc UK p amp p Overseas prices 3 80 each surface mail 5 25 each airmail We can also supply issues from earlier years 1998 except Jan to May July Nov Dec 1999 2000 except Feb July 2001 except May Oct Where we do not have an issue a photocopy of any one article or one part of a series can be provided at the same price ORDER FORM BACK ISSUES PHOTOCOPIES INDEXES L Send back issues dated L Send photocopies of article title and issue date L Send copies of last five years ind
6. Creating an Event I PR e Ltd gii l Counter By Clive Max Maxfield and Alvin Brown INTERGRAPH l o l COMPUTER SYSTEMS 3D GRAPHICS A chapter from Intergraph s _ E iat ein ee eee oe i book that explains computer graphics technology in an interesting and I il orders l Ae b k l understandable way with full colour graphics l TA aad ahah l Payments must be by card or in Sterling cheque or bank I EXTRA ARTICLE ON VOL 1 amp 2 I CAI Graw VON a UR Dank i i Normally supplied within seven days of receipt of order i THE LIFE amp WORKS OF KONRAD ZUSE a brilliant pioneer in the Send a copy of this form or order by letter if you do not wish to evolution of computers A bonus article on his life and work written by l cut your issue i his eldest son including many previously unpublished photographs Everyday Practical Electronics July 2002 499 Constructional Project SIMPLE AUDIO CIRCUITS Part 3 Power Supplies Loudspeakers Crossover Networks and Filters RAYMOND HAIGH A selection of pic n mix low cost audio circuits from preamplifier to speaker smaller power amplifiers May 02 is all that is required dry batteries repre sent a suitable power supply However when the output is expected to exceed the half watt level for sustained periods a mains power unit is more appropriate Savings in the cost of batteries will quick ly cover expenditure on components Compromises
7. LM380N Receiver 6 34 TDA2003 Interface Twin TDA2003 X Canute Tide Predictor Na 3 05 le eee a JUNE 02 3 imple Audio Circuits 2 Low Med and Hig tale Gen Frequency Generator Counter se rao a ee Input Impedance Preamplifiers Single Trans g Meter Low Noise Preamplifier Dual Trans EPE Moodloop AUG 00 271 5 47 Tone Control Quiz Game Indicator 272 4 52 Bandpass Filter Handy Amp 273 4 52 Frequency Standard Generator Receiver Active Ferrite Loop Aerial SEPT 00 4 67 Digital Remote Control IR Decoder Software only A Biopic Heartbeat Monitor SULY 702 4 PIC Dual Channel Virtual Scope OCT 00 5 15 Dual Output Power Supply Handclap Switch NOV 00 3 96 Crossover Audio Filter PIC Pulsometer Software only Infra Red Autoswitch ET EPE StyloPIC Lead DEC o0 Rotary Combination Lock Main Board Interface Board ve Using the PIC s PCLATH Command Software only x PIC Monitored Dual PSU 1 PSU Monitor Unit Static Field Detector Multi project PCB Two Way ieron TAN EPE SOFTWARE UFO Detector and Event Recorder Software programs for EPE projects marked with a single asterisk are available on 3 5 inch Magnetic Anomaly Detector PC compatible disks or free from our Internet site The following disks are available PIC Event Recorder Tutorial Mar May 98 PIC Toolkit Mk2 V2 4d May Jun 99 EPE Disk 1 Apr 95 Dec 98 Audio Alarm EPE Disk 2 uy
8. UBE suffix and the U stands for unbuffered The UBE version should always be used if it is specified in a components list but the standard BE variety should otherwise be used An E in a suffix is not the only letter used to indicate a plastic d i l encapsula tion Both P and N are commonly used to indicate this type of encapsulation and there are further variants such as G or H There are often two or three letters in the suffix and some manufac turers seem to use one letter to denote the case material plastic or ceramic and another to indicate the pinout config uration More commonly an additional letter is used to indicate whether the device is a commercial grade component or a higher grade type such as an indus trial or military type Most EPE projects normally require the bog standard commercial variety and these normally have C in the suf fix Higher grade devices should work perfectly well if used instead of a stan dard commercial grade component since they are all basically the same chip The superior versions have wider Operating temperature ranges and may be superior in other respects Euro ICs Some integrated circuits have European type numbers and these start with a T followed by two letters a serial Everyday Practical Electronics July 2002 number and a suffix letter e g TBA820M Devices of this type have the same type number r
9. age response of the ADC but we also need to look at the time and frequency aspects of converters ADCs take a finite time to con vert an analogue voltage to digital form this means that there is a finite number of conversions per second this is the sam pling frequency There is a very important rule that states that we must sample a waveform at a rate of at least twice the highest frequency in the waveform If we fail to do this the sampled waveform will be a distorted and inaccurate representation of the original in the worse cases the sampled waveform may end up completely different from the original The rule is known as the Nyquist crite Resolution rion or sampling theorem and_ the process by which dis 12 5 tortion occurs due to 6 3 inadequate sampling 0 4 is called aliasing The 0 98 minimum sampling 0 0224 frequency of twice the 0 0015 signal frequency is 0 00010 known as the Nyquist rate Later we do a Lab experiment to illustrate this The illustration in Fig 9 3 shows an ana logue waveform and three sampled ver sions of the waveform at different sampling rates Waveforms b to d are obtained using a sample and hold circuit which would form part of an ADC In an ADC it is the stable value from the sample and hold output that is converted to digital form The signals in Fig 9 3 are all analogue in nature they are not digital codes The flat held parts of waveforms b to d can still ta
10. own circuits We pay between 10 and 50 for all material published depending on length and technical merit We re looking for novel applications and eal ar fi nH amp amp p circuit designs not simply mechanical electrical or software a ideas Ideas must be the reader s own work and must not WIN A PICO PC BASED J have been submitted for publication elsewhere The OSCILLOSCOPE WORTH 586 circuits shown have NOT been proven by us ngenuity e 100MS s Dual Channel Storage Oscilloscope Unlimited is open to ALL abilities but items for consideration in SOMHz Spectrum Analyser this column should be typed or word processed with a brief e Multimeter Frequency Meter circuit description between 100 and 500 words maximum and Signal Generator full circuit diagram showing all relevant component values If you have a novel circuit idea which would be Please draw all circuit schematics as clearly as possible of use to other readers then a Pico Technology Send your circuit ideas to Alan Winstanley Ingenuity PC based oscilloscope could be yours Unlimited Wimborne Publishing Ltd 408 Wimborne Road Every 12 months Pico Technology will be East Ferndown Dorset BH22 9ND We do not accept sub awarding an ADC200 100 digital storage missions for U via E mail oscilloscope for the best IU submission In Your ideas could earn you some cash and a prize addition a DrDAQ Data Logger Scope worth 69 will be presented to th
11. 19 a w g enamelled copper wire for coils up to 2mH Use 22 s w g 21 a w g enamelled copper wire for 2 5mH to 3 5mH coils See illustration for details of bobbin and core will be suitable for all of the power ampli fiers described in Part 1 The performance of electrolytic capaci tors can become uncertain at high audio frequencies and the best crossover net works use components with a paper poly ester or polypropylene dielectric Tolerances Variations in the composition of ferrite rod will affect the tabulated inductor values shown in Table 4 by plus or minus 10 per cent or so Bipolar electrolytics whether purchased or homemade have a tolerance at best of plus or minus 20 per cent Fortunately loudspeaker crossover net works are very forgiving and component spreads even greater than this produce no audible difference When calculated values are being rounded up or down it is prudent to err on the high side with inductors and on the low side with capacitors BANDPASS FILTERS Mention has already been made of the desirability of restricting the audio band width of speakers used primarily for speech communication An inductor and capacitor can be combined to produce a bandpass effect and a typical circuit is given in Fig 3c As a Starting point select the inductor and capacitor values for a centre frequency of 1000Hz 1kHz If a more severe atten uation of frequencies below 300Hz and above 3000Hz 3kHz
12. 6 50 Kit includes wound coil cut out case meter scale PCB amp ALL components KIT 848 32 95 EPE PROJECT PICS Programmed PICs for all EPE Projects 16C84 18F84 16C71 All 5 90 each 10 inc VAT amp postage TEACH IN 2000 Full set of top quality NEW components for this educa tional series All parts as specified by EPE Kit includes breadboard wire croc clips pins and all components for experiments as listed in introduction to Part 1 Batteries and tools not included TEACH IN 2000 KIT 879 44 95 MULTIMETER 14 45 SPACEWRITER An innovative and exciting project E Wave the wand through the air and your message appears Programmable to hold any message up to 16 digits long Comes pre loaded with MERRY XMA Kit includes PCB all components amp tube plus instructions for message loading KIT 849 12V EPROM ERASER A safe low cost eraser for up to 4 EPROMS at a time in less than 20 minutes Operates from a 12V supply 400mA Used extensively for mobile work updating equipment in the field etc Also in educational situations where mains supplies are not allowed Safety interlock prevents contact with UV KIT 790 eat ea eters 29 90 SUPER BAT DETECTOR 1 WATT O P BUILT IN SPEAKER COMPACT CASE 20kHz 140kHz NEW DESIGN WITH 40kHz MIC A new circuit using a full bridge audio amplifier i c internal speaker and headphone tape sock
13. 600 watt model 330 watt continuous 79 97 Ref VER4 10 WATT SILICON SOLAR PANEL 10 year life waterproof 365mm x 365mm x 26mm 14V 10W 1 8kg framed 84 99 Ref PAN BULL ELECTRICAL UNIT D HENFIELD BUSINESS PARK HENFIELD SUSSEX BNS5 9SL TERMS CASH PO OR CHEQUE WITH ORDER PLUS 5 00 P amp P UK PLUS VAT 24 HOUR SERVICE 7 50 UK PLUS VAT OVERSEAS ORDERS AT COST PLUS 3 50 ACCESS VISA SWITCH ACCEPTED phone 01273 491490 Fax 491813 Sales bull electrical co uk STICKY LABELS Small address labels etc are very useful and can be ordered online at www stickon co uk MICROSOFT TRACKBALL AND MOUSE Called the Microsoft Ballpoint this has 4 buttons a trackball and PS2 connector Will work with most PCs 5 99 Ref EP50 MAXON WALKIE TALKIES up to 2 mile range UK legal 300 channel 2 x walkie talkies 74 95 Ref Maxon1 Chargers 14 Ref Maxonc battery packs 12 Ref Maxonb otherwise uses AAA batteries 2 WAY MIRROR KIT Contains enough material to make up to a 500mm x 2200mm mirror excl glass full instructions 19 95 Ref WFO01 22 AIR RIFLE Under lever type powerful Chinese training rifle 38 26 Ref A1047 500 pellets 2 68 Ref A1091 22 AIR RIFLE STANDARD TYPE Chinese training rifle on legal limit for air rifles 29 75 Ref A1040 Pellets 2 68 Ref A1091 SHUT THE BOX Check out www bullybeef co uk for a range of pub games and magic tricks WANT TO MAKE SOME MONEY STUCK F
14. Even if we no longer have a back issue containing a particular project we can provide a photocopy of that article providing it is less than five years old See the Back Issues page in this issue for prices Everyday Practical Electronics July 2002 by the various tools available tracks and pads can be removed or added to make minor additions to the layout the printout can be re sized and even specified for place ment on the page which can save valuable acetate Don t forget to save regularly while editing My 1280 x 1024 screen gives a resolution in PSP of about 150 pixels inch which is adequate for good resolution print outs with a manageable number of pixels to edit Poorly reproduced magazine layouts are as simple and the cheapest scanner should be adequate Open PSP go to File Acquire and use the TWAIN interface to scan the magazine copy Use Lineart Resolution 200 Then edit the layout as above Three additional points for making best p c b production 1 Mirror the layout before printing on acetate to allow the printed tracks to be in intimate contact with the photosensitive layer when exposing the board 2 Special ink jet sand finish acetate can produce acceptable masters with ink jet printers but the cartridge and printer must be perfect Any missing scan lines will etch hair line track breaks on the final board 3 For consistent high quality masters a cheap 600 lines per inch laser printer is worth t
15. Fig 9 11 Response of Gas Sensor to alcohol Everyday Practical Electronics July 2002 533 vary VR2 until the output is OV The circuit is then ready to be tested with gases Testing is straightforward as long as you are careful Ethanol alcohol is probably the best to use as it is readily available Soak a piece of cotton wool in some alco hol e g vodka and place it close to the sensor The output of the circuit should change as indicated in Fig 9 11 The output for our test circuit reached about 3 5V The reaction time is about 10 seconds You can repeat the tests with other gases such as butane Note that this circuit is not calibrated Also note that the output will be negative if you have the sensor and com pensator the wrong way round Lab 9 2 A D Converter Demonstration Circuit It is beyond the scope of these articles to provide complete circuits for ADCs partly because there are so many available Here we will show how to control a common ADC at low speed so that the binary output can be observed for different input voltages The complete circuit is shown in Fig 9 12 and it uses a readily available National Semiconductor ADC0804 8 bit ADC IC2 The ADC has three control inputs chip select CS write WR and read RD together with two analogue inputs Vac and Vino The final input is for a reference voltage and is denoted as V ef 2 The binary output goes from 00000000 at Vi to LII11111 at V ep For e
16. Ingenuity Unlimited June 02 Page 406 To prevent the i c outputs IC2 IC3 from adversely affecting each other 1N4148 signal diodes should be inserted between each i c pin and the respective e d The anode on the pin and cathode on the l e d World Lamp June 02 Where it is said that VR1 should be turned clockwise this should read anti clockwise and where anti clockwise clockwise Toolkit TK3 Updated files for V1 2 are now on our FTP site Only files Disk 1 and Disk 3 are affected 507 A COMPLETE RANGE OF A Complete range of regulated inverters to power 220V and 240V AC INVE RTE R S equipment via a car lorry or boat battery Due to their high performance a gt 90 the inverters generate very little heat The high stability of the 150W TO 2500W 12V amp 24V output frequency 1 makes them equally suitable to power BK ELECTRONICS ne sensitive devices These inverters generate a modified sine wave which are considerably superior to the square waves which are produced by most other inverters Due to this superior feature they are capable of powering electrical equipment such as TV s videos desktop amp notepad computers microwave ovens electrical lamps pumps battery chargers etc Low Battery Alarm The inverters give an audible warning signal when the battery voltage is lower than 10 5V 21V for the 24V version The inverter automatically shuts off when the battery voltage drops below 10V 20V for the 24V
17. PSP7 RD7 RE2 AN7 CS RE1 AN6 WR T Kol Hyl Dra OF OF KI e E ES EA ES Bul EAI M Eel E2 Ee Ee NGF OF OF OF OF OF OF OF a a S T A NN S Og a CLK DATA Vpp OV RM2 10k EAB SSIs 1 es Sai SSrretreris Ss aa ke Eas Se Se Ss eae PROGRAMMER mm RM1 10k O o aS SSS KEYBOARD m Oz Js 8 Fig 1 Main control circuit diagram for the EPE StyloPIC us Below Trackside of the prototype printed circuit board for the EPE StyloPIC in which g the integral keyboard tracks can be seen The large capacitor may be mounted on tae either side of the board to suit the housing used d og 591 O ON OFF Q 9V O 0 All contacts except for the eight con nected to the PIC s Port B are biassed nor mally high via individual resistors eight within each of resistor modules RM1 and RM2 plus two designated as RI and R4 The connections to Port B RBO to RB7 are held normally high by the PIC s eight internal pull up resistors The stylus which causes the notes to be triggered is connected to the OV line When it connects with a note key the respective PIC line is taken low the PIC responding according to which line has been affected Everyday Practical Electronics July 2002 489 In response to music keys being activat ed as opposed to activating the Mode Change key the PIC increments an inter nal counter at a rate related to the note fre quency required The counter s value is output via
18. Stylophone related sites while www yahoo com has 1610 sites available Some other sites not only offer history and other information about the output value to PORTA Stylophone but also offer second hand ones for sale for about US 70 on one site There are also sites that allow you to download and play with simulations of the Stylophone on your PC Other sites deal with the spin offs that resulted from the Stylophone craze includ ing information on the musicians and groups who used the instrument on their recordings such as David Bowie for example on his Space Oddity spelled Odyssey on some sites never mind it s a superb track whatever its name There are too many sites for the author to provide a list of the most interesting ones but one in particular is worth high lighting www stylophone fsnet co uk which the author found especially fascinat ing and from which the earlier history paragraphs were distilled there is much more and very interesting information in the original browse it The images of a Stylophone also came from this site PUTTING ON THE STYLE Whilst the heyday of the Stylophone is long gone it continues to live on as an excellent example of how someone s inno vative brainwave materialised as a product that really caught people s imagination It is hoped that many of you will find enjoy ment through playing with the author s modern re interpretation of th
19. The last two features are optional and may be built onto an additional printed cir cuit board which may also be interfaced to a standard intruder alarm system SYNC LOCKING The Rotary Combination Lock has one significant difference to the old mechani cal lock it needs to be turned in sync with a pulsed 1 e d That is the lock s dial must point to each number in sequence at the moment that an l e d pulses Once opened the lock is closed again by turning the dial to a Reset digit Assuming that the rotary dial has twelve positions there is one chance in 20 736 that is 124 that a prospective thief would randomly hit the right combination In practice however due to the con struction of the wafer rotary switch the chances of randomly hitting the right com bination are much less than this On the 512 other hand there is better than one chance in two that the would be thief s first move will trigger an alarm A particular advantage of the Rotary Combination Lock is that its fascia may be artistically altered to suit every taste In fact the lock need not even be rotary the circuit would also work with a standard keypad or with various arrangements of momentary action normally open switches These switches need not even be mounted together in the same place CIRCUIT DESCRIPTION The Rotary Combination Lock is based on a standard cascaded latch using four AND gates IC2a to IC2d as shown in Fig
20. and we choose the right value for the con stant k then we get a temperature stable voltage reference We can obtain a current that is propor tional to the difference in Vgg using the VCONSTANT Fig 3 Here lour iS proportional to the difference between the transistors Vpe voltages and it has a positive tempera ture coefficient 519 circuit in Fig 3 Here resistor R1 acts as a current source as both Veonstant and Var of TR1 are fixed The value of Jgy7 1s equal to the current in resistor R2 ignoring TR2 s base current The current in R2 is set by the voltage across it which is the difference in the Vgg values AV zz of the two transistors Thus Tour is proportional to AVpz To get a volt age proportional to AVgg we just pass Ioyr through a resistor The collector c of TR2 is the output of a current source and can therefore be set to any voltage within the operating range of the source If we connect it to a voltage equal to Vgr supplied from the base of a conducting transistor with its emitter con nected to ground see Fig 4 then the volt age at the other end of a resistor R3 car rying lour will be at Ver R3 Iouyr As Iour is proportional to AVgz this gives us a reference voltage in the form we were looking for After choosing component values which give the correct value for k the voltage obtained is around 1 2V and is related to the band gap for silicon The voltage sta bility is about ten times
21. available from www epemag com Cheques or bank drafts in sterling only payable to Everyday Practical Electronics and sent to EPE Subs Dept Wimborne Publishing Ltd 408 Wimborne Road East Ferndown Dorset BH22 OND Tel 01202 873872 Fax 01202 874562 Email subs epemag wimborne co uk Also via the Web at http www epemag wimborne co uk Subscriptions start with the next available issue We accept MasterCard Amex Diners Club Switch or Visa For past issues see the Back Issues page BINDERS Binders to hold one volume 12 issues are available from the above address These are finished in blue p v c printed with the magazine logo in gold on the spine Price 5 95 plus 3 50 p amp p for overseas readers the postage is 6 00 to everywhere except Australia and Papua New Guinea which cost 10 50 Normally sent within seven days but please allow 28 days for delivery more for overseas Payment in sterling only please Visa Amex Diners Club Switch and MasterCard accepted Send fax or phone your card number and card expiry date with your name address etc Or order on our secure server via our UK web site Overseas customers your cred it card will be charged by the card provider in your local currency at the existing exchange rate Editor MIKE KENWARD Deputy Editor DAVID BARRINGTON Technical Editor JOHN BECKER Business Manager DAVID J LEAVER Subscriptions MARILYN GOLDBERG Administration FAY KENWAR
22. charged electrons The nucleus of any atom contains positively charged protons and neutrons no charge with the exception of hydrogen which consists of a proton Everyday Practical Electronics July 2002 The chemical prop erties of an atom are determined by its atomic number which is the number of protons in its nucleus The atomic mass is the number of protons plus the number of neutrons An isotope of an element has the same number of pro tons but a different number of neutrons Some isotopes are sta ble and do not decay but many are unstable and undergo spontaneous disintegration forming another element and releasing elec tromagnetic radiation gamma rays or X rays or elementary particles such as beta or alpha particles Alpha particle An alpha particle is a heli um nucleus positively charged which is rel atively heavy compared with other particles and is easily absorbed by the air or materials such as paper The alpha particle is changed into a helium atom by capturing two elec trons from other atoms such as nitrogen and oxygen atoms in the atmosphere Beta particle Beta decay is character ized by a nuclear reaction in which the atomic number changes but not the atomic mass Beta particles can be negatrons elec trons or positrons which have the mass of an electron but with a positive charge Gamma ray emission Many alpha and beta emission processes leave the nucleus in an excited state which then r
23. effectively bypass the mains insulation of the apparatus X Class capacitors are not permissible in that mode Clearly it is difficult to cover this in any depth without reference to the lengthy technical standards something that I feel goes beyond the remit of Circuit Surgery Nevertheless even though EPE is a hob byist magazine where relevant we do try to set a good example by applying stan dards used by experts ARW More Supply Surprises Back in April 2002 Circuit Surgery we recounted the tale with hopefully a happy ending of a reader who had purchased a Yaesu transceiver but couldn t locate a suit able Battery Charger for it After talking to the manufacturers we suggested the RS 250 1397 basic charging unit I then heard back from George Jacobs who writes I was ever so relieved to hear that my battery problem had been solved thank you ever so much I went along with your opinion and decided to buy the suggested power unit However when I rang RS Components they said they could not help me because they do not supply individual customers only companies and business etc That really flattened me I have written twice to Yaesu but they have not replied I may have to sell the Transceiver and buy another model instead I was dismayed to hear that you had been turned away when you tried to buy the recharger Firstly for the benefit of readers in the USA and elsewhere RS Components has nothing to do with the ve
24. heatsink supplied You just supply a 24VAC 3A transformer PCB 55x112mm Mains operation 1007KT 16 95 IN BARGA ters can be received on an ordinary VHF FM radio between 88 108MHz Available in Kit Form KT or Assembled amp Tested AS TELEPHONE SURVEILLANCE MTTX MINIATURE TELEPHONE TRANSMITTER Attaches anywhere to phone line Transmits only when phone is used Tune in your radio and hear both parties 300m range Uses line as aerial amp power source 20x45mm 3016KT 8 95 AS3016 14 95 TRI TELEPHONE RECORDING INTERFACE Automatically record all conversations Connects between phone line amp tape recorder not supplied Operates recorders with 1 5 12V battery systems Powered from line 50x33mm 3033KT 9 95 AS3033 18 95 TPA TELEPHONE PICK UP AMPLIFIER WIRELESS PHONE BUG Place pick up coil on the phone line or near phone earpiece and hear both sides of the conversation 3055KT 11 95 AS3055 20 95 HIGH POWER TRANSMITTERS 1 WATT FM TRANSMITTER Easy to construct Delivers a crisp clear signal Two stage circuit Kit includes microphone and requires a simple open dipole aerial 8 30VDC PCB 42x45mm 1009KT 14 95 4 WATT FM TRANSMITTER Comprises three RF stages and an audio preamplifier stage Piezoelectric microphone supplied or you can use a separate preampli fier circuit Antenna can be an open dipole or Ground Plane Ideal project for those who wish to get started in the fascinating world of F
25. methods Contents waves and pulses passive components active components and ICs linear circuits block and circuit diagrams how radio works disc and tape record ing elements of TV and radar digital signals gating and logic circuits counting and correcting micro processors calculators and computers miscellaneous systems Order code NE23 13 99 199 pages SCROGGIE S FOUNDATIONS OF WIRELESS AND ELECTRONICS ELEVENTH EDITION S W Amos and Roger Amos Scroggie s Foundations is a classic text for anyone work ing with electronics who needs to know the art and craft of the subject It covers both the theory and practical aspects of a huge range of topics from valve and tube technology and the application of cathode ray tubes to radar to digital tape systems and optical recording techniques Since Foundations of Wireless was first published over 60 years ago it has helped many thousands of readers to become familiar with the principles of radio and electronics The original author Sowerby was succeeded by Scroggie in the 1940s whose name became synonymous with this classic primer for practitioners and students alike Stan Amos one of the fathers of modern electronics and the author of many well known books in the area took over the revision of this book in the 1980s and it is he with his son who have produced this latest version 400 pages Order code NE27 21 99 GETTING THE MOST FROM YOUR MULTIMETER R A
26. of Usenet including those it inherited from Deja News This is a priceless information resource that all readers should become famil iar with It works extremely well and runs directly in your web browser as an online newsreader Still on the subject of Usenet archives there is a fascinating archive of the last twenty years of Usenet posts at http www google com googlegroups archive_announce_20 html Read about the first mention of Microsoft May 1981 the first fax machine in February 1983 and the first mention of Tim Berners Lee s world wide web project August 1991 On the 30 March 1998 we see the first mention of Google itself which has since evolved from the Stanford University mathematical model into today s indispensable research tool Lastly if you are at all keen on using the Internet for research you should download the extremely handy web browser toolbar from Google which runs in Windows and needs Microsoft Internet Explorer version 5 or later Tiscali 10 0 Despairing of spiralling phone bills and resigned to the fact that broadband access will not arrive in the neighbourhood any day now I finally ditched a LineOne now Tiscali Surftime tariff which was paid for with the quarterly phone account I signed up for a FRIACO account flat rate internet access call origination i e an unmetered connection with Tiscali instead This offers a 14 99 fixed price service with no minimum call charge and
27. will be used to refer to the switch connected to Port A bit X The uncommitted l e d outputs are connected to Port B Ports A and B are initialised accordingly The program comprises a series of table calls and jumps with paus es waiting on a button press to allow the value returned from a table to be viewed on the l e d s The first operation from the example program after initialisation is shown in Listings 1 and 2 the grammar used is TASM The first two lines in Listing 1 set all bits in PCLATH to zero except bit 3 The table in Listing 2 starts at address 087Fh Table 2 shows this address is in page 1 sub page 0 meaning only bit 3 in PCLATH should be set to make it equal to O8h The third line in Listing 1 sets the table line access parameter The fourth line calls the table whereby bits 3 and 4 of PCLATH are prepended to placed in front of the opcode to give the full table address as in Fig 2 Execution now passes to the first line in Listing 2 There the first five bits in PCLATH are prepended to the ALU result of the arithmetic operation as in Fig 1 program counter program counter Fig 2 Setting the Program Counter for a CALL or GOTO Instruction 510 Since the value in the working register W is 2 the program counter jumps to the third data line in the table and returns a value of 10000110 which is then shown on the l e d display at the fifth line of Listing 1 The sixth line returns PCL
28. 8 is shown in Fig 5 It clearly illustrates the C12 2200u SK1 a AUDIO OUTPUT SEE TEXT Fig 5 The attack and decay of a note as controlled by the envelope shaper attack as a note is triggered by a pulse from the PIC and the subsequent decay of the amplitude when the pulse has ended Note that the software has been written so that the PIC s trigger pulse remains high for as long as stylus contact with the key is maintained This allows a certain amount of colour to be introduced to the musi cian s playing Whilst VR1 is shown as a preset poten tiometer mounted on the p c b an exter nal rotary pot could be used instead mounted in the chosen case In this instance a logarithmic log potentiometer is recommended An L272 audio amplifier IC5 is used for the final output stage This device is capable of outputting about 1W and is suitable for coupling into loudspeakers or headphones having impedances as low as 8Q The output is a c coupled via capacitor C12 and may also be fed to the line input of a normal domestic amplifier The device has been given a gain of about x5 and the maximum output level is around 3V peak to peak Resistor R17 and capacitor C11 give stability to this power op amp which is actually a dual channel device although only one channel is used POWER SUPPLY The circuit is basically run at 5V as reg ulated by IC3 Fig 1 except for the power amp IC5 whi
29. Analogue to Digital Conversion 528 Sampling and Nuclear Radiation Sensing by lan Bell and Dave Chesmore Regulars and Services EDITORIAL 475 NEWS Barry Fox highlights technology s leading edge 482 Plus everyday news from the world of electronics READOUT John Becker addresses general points arising 495 BACK ISSUES Did you miss these Many now on CD ROM 498 l SHOPTALK with David Barrington 507 a The essential guide to component buying for EPE projects 1 F PLEASE TAKE NOTE s 3 World Lamp L E D Sequencer Toolkit TK3 507 ao CD ROMS FOR ELECTRONICS 524 A wide range of CD ROMs for hobbyists students and engineers DIRECT BOOK SERVICE 536 A wide range of technical books available by mail order PRINTED CIRCUIT BOARD AND SOFTWARE SERVICE 539 PCBs for EPE projects Plus EPE software Wimborne Publishing Ltd 2002 Copyright in all drawings photographs and articles published in ELECTRONICS MANUALS 540 EVERYDAY PRACTICAL ELECTRONICS is fully Essential reference works for hobbyists students and service engineers protected and reproduction or imitations in whole or in part are expressly forbidden ADVERTISERS INDEX 544 Our August 2002 issue will be published on Thursday tent 11 July 2002 See page 467 for details Readers Services Editorial and Advertisement Departments 475 Everyday Practical Electronics July 2002 465 Visit our website www distel co uk GIANT 10 7 SEGMENT HEN es YS A bulk purchase enable
30. Mathematics is kept to a minimum and all calculations are explained Clear circuit simulations PRICES Hobbyist Student ccsscssceeeessesseeeeeeeeseseeeeseneeens 45 inc VAT _ _ Institutional Schools HE FE Industry 99 plus VAT Prices for each of the CD ROMs above are Institutional 10 user Network Licence 199 plus VAT Order form on third page Site LIGCCNG 6 iesuteiiseceancativaiincsesencdtarndodindaiaanetnnes 499 plus VAT UK and EU customers add VAT at 17 5 to plus VAT prices VERSION 2 PiCmicro MCU DEVELOPMENT BOARD Suitable for use with the three software packages listed below This flexible development board allows students to learn both how to program PiCmicro microcontrollers as well as program a range of 8 18 28 and 40 pin devices For experienced programmers all programming software is included in the PPP utility that comes with the development board For those who want to learn choose one or all of the packages below to use with the Development Board Makes it easier to develop PlICmicro projects Supports low cost Flash programmable PICmicro devices Fully featured integrated displays 13 individual I e d s quad 7 segment display and alphanumeric c d display Supports PlCmicro microcontrollers with A D converters Fully protected expansion bus for project work All inputs and outputs available on screw terminal connectors for easy connect
31. Port A RAO to RAS to six inputs of the 8 bit digital to analogue con verter DAC IC2 whose other two inputs are held permanently low The manner in which the counter s value is Output determines the tone of the note produced This stage and the subsequent envelope and amplifier stages are essential ly the same as used in the author s PIC Magick Musick design of EPE Jan 02 However whereas that design always gen erated a rising ramp waveform via the DAC the option to output a square wave form has been provided here This tone change function is triggered via the Mode key feeding into PIC pin REI Each time the key is activated the mode changes alternating between the ramp and square options It is believed that the original Stylophone probably output a squarewave but the author finds the ramp sawtooth waveform more harmonious to the ear Indeed as shown through Magick Musick when enve lope shaping is applied as well a very piano like sound is created The DAC is used in the mode which allows a voltage related output to be gener ated in respect of digital input values it can also generate current related outputs In the voltage output mode the voltage sig nal is taken from the device s REF refer ence pin with the two normal outputs OUTI and OUT2 connected to 5V and OV respectively If you wish to explore this Fig 3 Sawtooth waveform created via DAC IC2 490 device s attributes
32. a further selection of books see the next two issues of EPE BASIC RADIO PRINCIPLES AND TECHNOLOGY lan Poole Radio technology is becoming increasingly important in today s high technology society There are the traditional uses of radio which include broadcasting and point to point radio as well as the new technologies of satellites and cellular phones All of these developments mean there is a growing need for radio engineers at all levels Assuming a basic knowledge of electronics this book provides an easy to understand grounding in the topic Chapters in the book Radio Today Yesterday and Tomorrow Radio Waves and Propagation Capacitors Inductors and Filters Modulation Receivers Transmitters Antenna Systems Broadcasting Satellites Personal Communications Appendix Basic Calculations 263 pages Order code NE30 15 99 PROJECTS FOR RADIO AMATEURS AND S W L S R A Penfold This book describes a number of electronic circuits most of which are quite simple which can be used to enhance the performance of most short wave radio systems The circuits covered include An aerial tuning unit A simple active aerial An add on b f o for portable sets A wavetrap to combat signals on spurious responses An audio notch filter A parametric equaliser C W and S S B audio filters Simple noise limiters A speech processor A volume expander Other useful circuits include a crystal oscillator and RTTY C W tone decoder a
33. a heatsink and rigid optical mount Dims of block are 50 w x 50d x 15 hmm Integral features include over tem perature shutdown current control laser OK ouput and gated TTL ON OFF Many uses for experimental optics comms amp lightshows etc Supplied complete with data sheet Order as TD91 ONLY 24 95 a Virtually every type of power supply you can imagine Over 10 000 Power Supplies Ex Stock Call or see our web site RELAYS 200 000 FROM STOCK Save s by choosing your next relay from our Massive Stocks covering types such as Military Octal Cradle Hermetically Sealed Continental Contactors Time Delay Reed Mercury Wetted Solid State Printed Circuit Mounting etc CALL or see our web site www distel co uk for more information Many obsolete types from stock Save s ALL ENQUIRIES 0208 653 3333 FAX 0208 653 8888 ELE EN CI m AVE a m j j lo l All prices for UK Mainland UK customers add 17 5 VAT to TOTAL order amount Minimum order 10 Bona Fide account orders accepted from Govemment Schools Universities and Local Authorities minimum account order 50 Cheques over 100 are subject to 7 working days clearance Carriage charges A 3 50 B 6 50 C 10 we Est D 15 00 E 18 00 F CALL Allow approx 3 days for shipping faster CALL All goods supplied to our Standard Conditions of Sale which can be viewed at our website and VISA as 26 unless stated guar
34. a plate earth and the voltage discharged from an electrode through the rodent I envisage some thing in solid state form At present I am using mains voltage for this purpose It fries the rodents but each time I have to reset the 6A circuit breaker and the unit is inconvenient as it cannot be used out of doors Any idea where I can look for information Anthony Bankside via email Goodness Anthony I dread to think what ani mal and human welfare organisations might think of your extermination practice and intent I will refrain from comment on this but if you wish to investigate high voltage generation in a broad sense the technology used in the Tesla coil gen erator for the DIY Tesla Lightning of March 01 might be of interest to you There are also many web sites devoted to Tesla coils do a search on Tesla via www google com Such voltages are of course highly dangerous RUGBY CLOCK Dear EPE I am thinking of decoding the time signals from Rugby to use in a data logger Has anybody made a program for a PIC Dave via email My PIC Time Machine Nov 97 plus Aug 98 does it The software s on our FTP site Everyday Practical Electronics July 2002 TEE Dof MAGAZINE FOR ELECTRONICS TECHNOLOGY amp COMPUTER PROJECTS We can supply back issues of EPE by post most issues from the past three years are available An EPE index for the last five years is also available see order form Alternativel
35. alarm sys tem but will also serve as a simple stand alone two zone alarm sys tem It is also capable of switching powerful alarm sounders and beacons TE Interface circuit may be used not only to interface the Rotary directly Besides this the Interface is capable of a variety of standard switching options of which four are described These include A single action pushbutton A dead man s handle strictly speaking this term has been superseded by more politically correct terminology A conditional switch A timer INTERFACE CIRCUIT The circuit for the Interface is relatively straightforward and its schematic diagram is shown in Fig 5 It uses a 7556 CMOS dual monostable timer IC1 which is used to close relays RLA and RLB for specific periods when pulses are received from the lock s main circuit board Presets VR1 and VR2 are used to set the duration of triggering of each of the mono stable timers between about 0 7 seconds and two and a half minutes with the com ponent values shown The values of capac itors C2 and C5 may be increased for longer timing periods IC1 requires a negative pulse at each of its trigger inputs pin 6 and pin 8 A nega tive going Alarm pulse is applied to Cla s trigger pin 6 from the main lock circuit 516 However the lock s Duress pulse is positive going so this needs to be inverted before it is presented to IC1b s trigger pin 8 This is accomp
36. amp Testing ELECTRONIC PROJECTS FOR EXPERIMENTERS R A Penfold Many electronic hobbyists who have been pursuing their hobby for a number of years seem to suffer from the dreaded seen it all before syndrome This book is fairly and squarely aimed at sufferers of this complaint plus any other electronics enthusiasts who yearn to try some thing a bit different No doubt many of the projects fea tured here have practical applications but they are all worth a try for their interest value alone The subjects covered include Magnetic field detector Basic Hall effect compass Hall effect audio isolator Voice scrambler descrambler Bat detector Bat style echo loca tion Noise cancelling LED stroboscope Infra red torch Electronic breeze detector Class D power amplifier Strain gauge amplifier Super hearing aid Order code BP371 5 45 ELECTRONIC PROJECT BUILDING FOR BEGINNERS R A Penfold This book is for complete beginners to electronic project building It provides a complete introduction to the practi cal side of this fascinating hobby including the following topics Component identification and buying the right parts resistor colour codes capacitor value markings etc advice on buying the right tools for the job soldering making easy work of the hard wiring construction meth ods including stripboard custom printed circuit boards plain matrix boards surface mount boards and wire wrap ping finish
37. ancillary equipment to be connected to the power supply and increase this by at least 25 per cent to allow for the reactive load present ed by the reservoir capacitor C5 The current requirements of the power ampli fiers were given in Part 1 For conve nience they are repeated here in Table 2 1A TIME DELAY SLOW BLOW FUSE EURO STYLE MAINS INLET PLUG Manufacturers usually indicate the cur Regulated Output rent delivering capacity of their mains V d c transformers by quoting a VA rating This 6 is of course the secondary output voltage 9 multiplied by the maximum current which 12 the transformer can supply 15 In Europe mains transformers often have two 115V primary windings and two NOTES identical secondary windings The primary windings must be series or parallel con nected to suit the local supply voltage and the secondary connected to deliver the desired output Parallel connecting the sec ondary will of course double the current available Connect the windings in phase or the transformer will be short circuited 35V working S COMPONENT SEE TABLE 1 FOR DETAILS OF VOLTAGE REGULATORS IC1 AND IC2 C3 IN OUT C6 100n REGULATED OUTPUT 1 C7 70u 470 REGULATED N UT OUTPUT 2 470 COM Q V O V C8 100n eon 70u OV O Fig 1 Circuit diagram for a Dual Output Regulated Power Supply Table 1 Component Ratings Transformer Sec Vrms 9 12 15 18 channel
38. and use P600D rectifiers Rectifiers With a capacitor input filter the rectifiers D1 to D4 must have a p i v peak inverse voltage rating at least three times the secondary voltage of the mains transformer Their current rating should be at least 50 per cent greater than the maximum load on the power supply Reservoir Capacitor The value of the reservoir capacitor in microfarads uF should be at least 2500 times the maximum load current in amps when the supply is regulated and double this value when unregulated The working voltage should be at least double the secondary voltage of the mains transformer Regulators The current rating of the voltage regulators IC1 and IC2 must of course be equal to or greater than the maximum current demand on the power supply The maximum input voltage rating usually 30V to 35V must be at least 1 5 times the secondary voltage of the mains transformer Regulator i c s are available in a range of output voltages suitable for the audio amplifiers May 02 and preamplifiers June 02 described in this Table 2 Power Amplifier Current Requirements Power Amp Speaker Imp Supply volts Current drain LC Ohms V d c A LM386N 1 4 6 0 13 LM386N 1 8 9 0 12 TDA7052 4 6 0 42 TDA7052 8 9 0 39 TBA820M 4 9 0 23 TBA820M 8 12 0 17 LM380N 4 12 0 23 LM380N 8 15 0 19 TDA2003 4 15 0 5 TDA2003 8 15 0 27 TDA2008 x 2 4 15 1 7 TDA2008 x 2 8 15 0 96 Power output 0 32 0 56 0 78 0 98 1 4
39. angle of the reference beam used to write the data match can the data be retrieved By enabling a large variety of angles to be used the amount of data that can be stored can be multiplied many times A wide variety of work is being under taken to fully investigate the new materi als Computer simulations of the atomic vibrational characteristics of real glasses Holographic data storage promises to revolutionise the way the computer industry stores data and could even spell the end for the trusty disk drive reoorts lan Poole and of the new chalcogenides are being performed Thus a greater understanding of the way in which light phonons are related to the vibrational modes can be gained In turn this can be used to gain a better under standing of the way data can be stored using these materials It is interesting to note that the early thermionic valve developments were great ly hindered by a lack of understanding of the way in which valves worked This team are aiming to gain as full an understanding as possible Polight s first storage product is being developed with investment partners Called the Holodisc this first product is a 500 Gbyte storage unit and uses a 250 to 500 micron thick element of chalcogenide This gives it a memory data density of around 110Gbit em a figure which is many times that of current disk drive technology It is expected that it will revolutionise the corporate back up and archive
40. as MPLAB for example It is available on 3 5in disk for which a small handling charge applies from the EPE Editorial office or by free download from the EPE ftp site The easiest access to the ftp site is via our main web site at Www epemag wim borne co uk At the top of the main page click on the ftp option then select in order of PUB PICS StyloPIC There are four files involved ASM TASM OBJ TASM HEX MPASM and MSG The latter holds the data Eeprom tuning values in the format specific to Toolkit TK3 whose software is also available for free download via our ftp site Non TK3 users will need to incorporate these values into the HEX file so that during program ming they are loaded into the PIC s data Eeprom commencing at location 0 PIC configuration is embedded into the HEX file OBJ users should configure the PIC for HS crystal WDT off POR on The printed circuit board includes con nections through which the PIC can be pro grammed using TK3 and its MK3 board The connections are in the author s stan dard order via TB1 see Fig 1 Remember to connect switch S2 after you have com pleted the programming Programmed PICs are available as dis cussed in this month s Shoptalk column which also provides essential information on component sourcing for the StyloPIC STYLOPHONE WEBSITES Doing a search on Stylophone via www google com revealed that at the time of writing it provides access to 2260
41. be the most envi ronmentally friendly if we think about global warming as it does not produce car bon dioxide but the waste products are cer tainly not environmentally friendly In medicine X rays are well known but radioactive isotopes are used for many pur poses such as labelling where the radioac tive material is used to label a chemical e g iodine and its movement through the body can be traced NUCLEAR RADIATION DETECTORS Perhaps the most well known radiation detector is the Geiger Muller GM tube A schematic diagram of a typical GM tube is shown in Fig 9 7 consisting of a tube filled with argon through which passes a wire The outside of the tube is grounded and the wire has about IkV on it Any radioactive particles this includes X rays and gamma rays entering the tube ionize the gas cre ating ions and electrons The electrons are attracted to the wire whilst the ions are attracted to the grounded tube The result ing drop in voltage at the wire is detected 531 THIN GOLD FILM RADIATION Example of a Geiger Muller tube p TYPE and amplified to produce a digital pulse which can be counted One problem with GM counters is that it takes time for the charge built up to dissi pate meaning that it exhibits a dead time producing an upper limit to the number of counts per second The dead time is of the order of 50ms to 200ms Example of a photomultiplier A second method is known as scintill
42. better than a Zener and can be further enhanced by more sophisticated circuits To get a practical reference circuit we note that the Voonstantr We require for the current source input can be Vef our ref erence output voltage clever isn t it The same voltage can also be used for Vpyas for the transistor supplying the Vp voltage Current to the whole circuit can be sup plied via a resistor R4 from the power supply which gives us a basic temperature compensated voltage reference see Fig 5 This circuit was published in 1971 by Robert Widlar a highly respected engineer whose name often headed up many National Semiconductor application notes and is one of the many implementa tions of the bandgap reference that are now available The output from Fig 5 would usually be buffered by an op amp to pre vent loading effects Other bandgap cir cuits put the op amp and reference in a feedback loop to further stabilise the cir cuit Bandgap references are available as integrated circuits such as the LM113 and LM10 from National Semiconductor IMB Capacitors Class of Y2 Roger Warrington writes With respect to Circuit Surgery in the June issue and the discussion about X Class and Y Class capacitors the statements you made are essentially correct However I feel that the effect of the difference between YI and Y2 caps ought to have been pointed out since getting it wrong could be lethal I speak as a retired safety tes
43. co uk Everyday Practical Electronics July 2002 PiCtutor V2 BACK in 98 we published John Beckers well acclaimed PIC Tutorial series of articles explaining to newcomers how to understand and use PIC microcontrollers The success of that series led to the production of a CD ROM based version in conjunction with Matrix Multimedia Ltd and known as PICtutor complete with its own simulator and development board A new version of P Ctutor has been introduced with many beneficially enhanced fea tures First whereas the original was based on the TASM assembly dialect John has revised V2 so that it is totally based upon the industry standard MPASM dialect giving a much more universal appeal to the tutorials demonstrations and development exercises Secondly the development board through which PICs can be programmed during the tutorials and in the user s own later applications has been totally redesigned with many new interface features and allowing four different PIC sizes to be programmed Of great significance too is the improvement that does away with the programming switches of V1 All program downloading is now fully under control of the PC computer via a specially developed suite of software that is included on the CD We are extremely pleased that Microchip the manufacturers of PICs has given its sup port to the new version To suit their marketing recommendations it has been renamed as Assembly for PlCmicro Microcontro
44. con firm it one has to have a detailed knowl edge of the spacing requirements for the particular voltage In any case it s safe to assume that your readers will have their fingers in the secondary circuit workings with the power on After all that s why they read the magazine A number of switch mode power supplies use Y capacitors between floating sec ondary circuits and the mains as an aid to suppressing interference or even to detect the presence of the mains Since there is no safety earth the requirement is for double or reinforced insulation This requires the use of two equal Y2 capacitors in series or one Y type Note that there is an earth leakage cur rent flowing through these caps and in the case of using two Y2 caps the current through a single one should not exceed the limit The limit varies with the standard medical standards being much more criti cal for instance However for non medical use in Class II equipment Class II means no safety earth the limit is normally 0 25mA Thus one can do the sums of E Xc and deduce a maximum value of Y capaci tance for 250V 50Hz of about 3nF Of course putting two in series will halve the effective capacitance so a single YI cap may be preferable Roger Warrington C Eng MIEE by email Thank you for filling us in with this technical information As we mentioned previously Y Class capacitors are rated for direct connection to earth although they
45. design previous ly published in EPE You may recall that in PIC Magick Musick there was a brief discussion about the difficulty of accurately generating exact frequencies when using a PIC That discus sion related to conventional frequency generation in a which a counter is incre mented by whole values minimum of one unit within a loop whose length is varied to change the resultant output frequency There is another technique whose princi ple has been used by the author in other non musical PIC applications in which fractional values can be added in the loop Once such instance was with his bike com puter PIC Agoras of April 87 in which distance was calculated in relation to pre cise wheel diameters and required the use of binary fractions However the author had not thought to relate this technique to music generation until Peter Hemsley of renown for his many PIC Tricks pointed out the possibil ity Thank you Peter it s a superb way of achieving accuracy and is used here in the StyloPIC To achieve it though a much higher clock frequency is required to control the PIC than is usually employed for many designs As you will see from Fig 1 the rate used here is 20MHz effectively the top rate at which a PICI6F877 is designed to operate although as many readers will have found PICs can often be driven at rates in excess of their specifications but we would be reluctant to actually publish over d
46. easy to achieve with speakers of 200mm 8in or more in diameter Mid range units are sometimes provided when the low frequency speaker is large 300mm to 450mm or 12in to 18in diam eter AS one would expect cones are lighter the compliance is often stiffer and the chassis can form a sealed enclosure High frequency units or tweeters have a very small diaphragm which is commonly dome shaped to improve sound dispersal Units of this kind always have sealed backs Whilst moving coil tweeters are the pre ferred option for hi fi applications horn loaded piezoelectric units are often fitted in the high power speaker systems used by musicians The impedance of these devices rises and their power consumption falls almost to zero as the applied frequency is lowered They do not therefore require a crossover unit and are easy to connect into multiple speaker systems COMMUNICATIONS Loudspeakers intended primarily for speech reproduction in communications equipment have to perform well over a restricted frequency range usually around 300Hz to 3000Hz Inexpensive speakers of the type manu factured for portable receivers are better suited for this purpose and if space is available a 102mm 4in diameter unit is to be preferred Clarity will be impaired if low frequencies are allowed to excite the cone of a speaker of this kind and mea sures to prevent this were discussed in Part 1 May 02 IMPED
47. electrical contact The output is taken from the n type layer and amplified The intrinsic layer which is p type sili con is doped with lithium in an unusual way A lithium layer is deposited onto the p type layer and the whole device heated to around 400 C at which point the lithium diffuses into the silicon and converts the p type into n type silicon While it is still at 400 C a d c potential is applied which causes the lithium ions to drift into the p type layer and replace holes The overall effect is for the intrinsic layer to act in a similar manner to the gas in a GM tube and when a particle impinges on the sensor a current spike is produced One other thing the sensor is cooled by liquid nitrogen to 196 C to reduce electri cal noise In fact if the sensor is allowed to reach room temperature its performance is degraded because the lithium will diffuse rapidly in the silicon If you have any queries directly related to this series you can write to the authors c o the Editorial address or you can email them at teach in epemag demon co uk no file attachments or general electronic queries please TEACH IN 2002 Lab Work 9 DAVE CHESMORE GAS SENSING DIGITAL SAMPLING AND EXPERIMENTS WITH AN ADC Lab 9 1 Gas Sensor Circuit AST month we discussed the princi zk of gas sensing Here we present a circuit capable of sensing butane ethanol hydrogen and methane It is based on the Nemoto NAP 7AU
48. given by Time 0 01 x 1000 x 0 7 7 secs Note that all these times are approximate as they depend upon the accuracy of the components used particularly the capaci tor Some electrolytic capacitors may have a tolerance error of as much as 50 per cent though most modern ones can do better As stated earlier if precise times are required a potentiometer wired as a variable resistor could be employed so that the exact time may be set The vari able resistor should be connected to the p c b pads P1 and P2 so that it is in series with resistor R3 this ensures that if the variable resistor is reduced to zero there is not a direct link to the positive supply The value of resistor R3 could be reduced to 1k if shorter times are required The maximum resistance per mitted is 1M beyond that timings may be unstable If very long timings are required the value of capacitor Cl could be increased though be cautious as large value electrolytics can be very leaky and you may find that Cl never charges sufficiently to complete the timing cycle Some experimentation may be necessary CONSTRUCTION Apart from the mains neon indicator LP1 all the components for the Infra Red Autoswitch are mounted on a small single sided printed circuit board The topside component layout and full size copper foil master pattern are shown in Fig 3 This board is available from the EPE PCB Service code 358 Begin constructio
49. hurriedly wound Andy Flind s Moodloop Aug 00 Andy is a good source of information on brainwaves and why you would want to stimulate them I did this because I wanted a Rife type of magnetic pulser and I was in too much dis comfort to bother with making a proper one with a proper frequency feed of squarewave a c as per Aubrey Scoon s The End to all Disease April 01 I knew from years earlier that my brain wave machine when fed into a one turn room loop coil could influence the mood of people in the room I was hoping that the d c spikes from it at 16 7Hz when fed into my small coil held close to my ear would be powerful enough to ease possible weeks of pain such as I had last year And it worked The pain was mostly gone within 24 hours and in 48 hours I was a happy man Why 16 7Hz That s the only Rife frequency that any brain wave machine can reach it s in the beta brain wave range Allegedly from Rife supporters that frequency is totally wrong for infections but I was again hoping that it would work It wasn t a forlorn hope as readers who follow alternative electrotherapy will real ize that while Rife has large numbers of fre quencies one for each ailment a certain Dr Robert Beck offers a similar coil type magnetic pulser but in Beck s case one 4Hz squarewave frequency does the lot So now I have just helped myself with a d c train of spikes not a c at an unapprove
50. if you increase note Concert A from 440Hz to 441Hz A at the next octave up is automatically increased to 882Hz exactly twice that of the lower note To change the pitch of the entire 25 note block Reset switch S2 is pressed while the unit is fully powered and the stylus applied to one of three keys Keeping the stylus on the selected key Reset is released and the program restarts from the beginning During the initialisa tion it recognises which key is active and the program jumps to an appropriate cor rection routine The interception routing is shown in Listing 1 As you will see if top C is keyed an increase in pitch is required Keying bot tom C causes a reduction in pitch while LISTING 1 btfss PORTE 2 is increase in tun ing freq needed top C keyed call TUNEUP yes btfss PORTB 7 is decrease in tuning freq need ed bot C keyed call TUNEDOWN yes btfss PORTD 6 is restore of orig tuning freq need ed A 440 key call RESTORETUNE yes call GETNOTES keying Concert A 440Hz A nearest to the left of the keyboard results in the author s defaults being restored Readers having TK3 and its board could actually change the pitch by as little as one least significant bit via the MSG file amendment programming option RESTORING Any changes actioned are automatically stored back to the first block in the Eeprom where they remain even after power has been switched off being recalled again wh
51. in detail its datasheet can be download free from www ti com An example of the ramp waveform gen erated is shown in Fig 3 ENVELOPE SHAPING Referring now to Fig 2 envelope shap ing is performed by transconductance amplifier IC4 an LM13600 device whose datasheet can be download from www nsc com it was also discussed in Circuit Surgery Dec 01 As in Magick Musick it is used as a volt age controlled amplifier VCA that is under pulsed control as an envelope shaper varying the amplitude of a frequency sig nal across a specific period In this appli cation the pulse control is applied from PIC pin REO to IC4 pin 1 The pulse is modified by the action of diode D2 capacitor C7 and the combined resistance of R7 and R9 As will be seen from the waveform in Fig 4 the voltage at IC4 pin 1 rises rapidly when the pulse arrives from REQ When it ceases the volt age across C7 decays at a rate determined by the current flowing through R7 and R9 Fig 4 The envelope shaping pulse at capacitor C7 It is the current that flows into IC4 pin 1 that determines the amplitude of the audio signal transconducted through IC4 from pin 4 to pin 5 and secondarily governed by the value of resistor R10 The signal at R10 is then buffered by I C4 s internal Darlington transistor and output via capac itor C8 to potentiometer VR1 and thence to the audio amplifier stage around ICS A typical waveform as seen at IC4 pin
52. inherent in the design of loudspeakers give rise to limitations which are normally overcome by the use of two or more units and a crossover Power supplies loudspeakers and asso ciated networks are the topics to be cov ered this month SUPPLY REGULATION A simple mains power supply compris ing a full wave rectifier and capacitor input filter will deliver an off load voltage of around 1 4 times the transformer sec ondary voltage With a secondary rated at 12V a c the off load d c output voltage will therefore I a modest output from one of the be almost 17V If the power supply output is close to the maximum safe operating voltage of the amplifier i c there is a dan ger that under no signal conditions the device will be ruined When fully loaded the d c output volt age will fall to around 14V with an ade quately rated transformer lower when the transformer specification has been skimped Voltage will therefore be low at the very moments when the power amplifi er is being called upon to deliver a high output These voltage variations are a cause of distortion and impair the performance of the power amplifier Moreover when high gain preamplifiers or radio tuners are fed from the same supply the variations can also result in instability even when sub stantial decoupling is provided POWER SUPPLY These problems can be avoided by regu lating the output of the power supply and a versatile circu
53. inputs from switches etc and drives motor in response Also runs standard demo sequence from memory All prices include VAT Add 3 00 p amp p Next day 6 99 E mail sales magenta2000 co uk 473 EVERYDAY EHEC TRONCS THE iNe MAGAZINE FOR ELECTRONICS TECHNOLOGY amp COMPUTER PROJECTS i technical enquiries cannot be answered over the tele Editorial Offices EVERYDAY PRACTICAL ELECTRONICS EDITORIAL WIMBORNE PUBLISHING LTD 408 WIMBORNE ROAD EAST FERNDOWN DORSET BH22 9ND Phone 01202 873872 Fax 01202 874562 Email enquiries epemag wimborne co uk Web Site http www epemag wimborne co uk EPE Online www epemag com EPE Online Shop www epemag wimborne co uk shopdoor htm See notes on Readers Technical Enquiries below we regret Advertisement Offices EVERYDAY PRACTICAL ELECTRONICS ADVERTISEMENTS VOL 31 No 7 JUNE 2002 MILL LODGE MILL LANE THORPE LE SOKEN ESSEX C016 OED Phone Fax 01255 861161 RIP OFF It s a pity when a few spoil it for everyone we see it all too often in modern society with football hooligans young vandals hackers and virus writers and of course those that are pre pared to rip someone else off for their own gain and glorification Why is this relevant to EPE well of course it should not be but then we exist in today s world just like everyone else SERIOUS OFFENCE Over the last twenty years or so we have had just one or two instances where item
54. is designed for students and professionals who need to learn how to program embedded microcontrollers in C The CD contains a course as well as all the software tools needed to create Hex code for a wide range of PlCmicro devices including a full C compiler for a wide range of PICmicro devices Although the course focuses on the use of the PlCmicro microcontrollers this CD ROM will provide a good grounding in C programming for any microcontroller Complete course in C as well as C programming for PlCmicro microcontrollers Highly interactive course Virtual C PlCmicro improves understanding Includes a C compiler for a wide range of PlCmicro devices Includes full Integrated Development Environment Includes MPLAB software Compatible with most PlCmicro programmers Includes a compiler for all the PlICmicro devices Minimum system requirements for these items Pentium PC running Windows 95 98 NT 2000 ME XP CD ROM drive 64MB RAM 10MB hard disk space 145 including VAT and postage 12V 500mA plug top PSU UK plug 7 25 way D type connecting cable 5 PiCmicro TUTORIALS AND PROGRAMMING FLOWCODE FOR PICmicro Flowcode is a very high level language programming system for PlCmicro microcontrollers based on_ flowcharts Flowcode allows you to design and simulate complex robotics and control systems in a matter of minutes Flowcode is a powerful language that uses macros to facilitate th
55. is required reduce the capacitor and increase the inductor value When using this network with ear phones connect both earpieces in parallel to produce an impedance of 16 ohms and perform the calculations on this basis Although extremely simple this mea sure will greatly improve the clarity of speech especially when signals are over laid by received or generated noise within the amplifiers CROSSOVER UNIT The circuit diagram for an inexpensive 8ohm Crossover Filter unit suitable for a multi purpose workshop speaker is shown FORMULAE FOR THE REACTANCE OF INDUCTORS AND CAPACITORS X 0 00628 f L ohms X 159000 ohms c fc where f is in Hertz L is in millihenries mH and C is in microfarads uF Fig 5 Creating a bipolar electrolytic from two capacitors FORMULAE FOR COMBINING CAPACITORS Two capacitors in series _CixC2 Cx 61462 Capacitors in parallel Cx C1 C2 C3 The working voltage of each capaci tor should be at least 1 5 times the peak to peak signal voltage developed across the loudspeaker at maximum input 505 GROSSO VRAA NDYO Ah Els COMPONENTS CROSSOVER AUDIO FILTER Capacitors C1 10u bipolar radial elect 50V Alternatively two 22u standard elect connected back to back see text and Fig 5 See Inductor L1 9 5mm 3 8in SHIOL dia ferrit ia ere TALK 63mm page 2 2in card hardboard and glue for bobbin TAP 100 TURNS C
56. maximum input frequency is typically 16kHz which means that the theoretical minimum sampling fre quency is 32kHz but the actual frequency is 44 1kHz There are some very clever ways of reducing the sampling rate compres sion e g MP3 but these rely on a knowl edge of the way in which sounds are produced and only work on the correct types of signal MP3 only works for speech AMPLITUDE FREQUENCY fete fe fgte fs fs fc FREQUENCY Fig 9 5 Aliasing in the frequency domain Everyday Practical Electronics July 2002 and music and would not work for com pressing video ANTI ALIASING FILTERS As we see from the experiments the Picoscope ADC 40 exhibits this behaviour which means that we can get incorrect results for high frequencies How do we stop this We use a low pass filter called an anti aliasing filter which is placed between the input signal and the ADC as shown in Fig 9 6 INPUT SIGNAL n BITS PER SAMPLE ANTI ALIASING FILTER Fig 9 6 Preceding an ADC by an anti aliasing filter The filter must have a sharp roll off and have a cut off frequency at less than f 2 One of the most common filters used nowa days is the switched capacitor filter similar to that used last month One of the Lab experiments this month uses a filter to stop aliasing on the Picoscope BANDWIDTH EXPANSION Now we have all the requisite concepts let us return to the idea that digital signal transmission needs a
57. now be about 8 minutes When the case is safely back together re connect the mains supply The printed circuit board should be positioned in the lid of the case using nylon self adhesive pillars Note the cutout slot for the IR sensor NEWSAGENTS ORDER FORM Please reserve deliver a copy of Everyday Practical Electronics for me each month Everyday Practical Electronics is published on the second Thursday of each month and distributed S O R by COMAG Make sure of your copy of EPE each month cut out or photostat this form fill it in and hand it to your newsagent 480 Everyday Practical Electronics July 2002 A roundup of the latest Everyday News from the world of electronics TV HISTORY REVISITED Big business ethics do not always favour the creative inventor as Barry Fox reports C to popular belief the world very seldom beats a path to an inventor s door waving a cheque book pioneers die broke and forgotten and big business lawyers make mincemeat of lone inventors The tragic story of how Edwin Howard Armstrong invented FM radio in 1933 and committed suicide in 1954 out of despair is well documented in Man of High Fidelity by Lawrence Lessing Bantam Books although be warned the book is a eulogy and lacks any index Armstrong struggled first to win fre quencies for FM broadcasting from the Federal Communications Commission and then to win royalties on radio equip ment from the gi
58. number and BE is the suffix The same method of identification is often used in component catalogues with no particular manufacturer being mentioned Some of the very large sup pliers do offer devices from a specific manufacturer and may even offer a choice of manufacturers in some cases Where there is a choice sim ply opt for whichever one is the cheaper There is a further complica tion with the 74 series TTL logic devices because various families of improved chips have been introduced over the years The original devices had basic type numbers that start Fig 1 The markings on integrated circuits usually include a ad with 74 end then had a lot of excess baggage two or three digit number e g 74245 The original TTL logic integrated circuits are now largely obsolete Later logic families are identified by adding two or three letters after the 74 part of the type number These are the identification letters for some common TTL logic families HC high speed CMOS e g 74HCO2 HCT high speed CMOS normal TTL logic levels e g 74HCTO2 LS low power Schottky e g 74LS02 LCX low voltage and high speed e g 74LCX02 LVX low noise low current and high speed e g 74LVX02 using Everyday Practical Electronics July 2002 There have been many other TTL logic families but these have not stood the test of time and you are unlikely to encounter them It is the first three in the
59. of development before they can be made successfully on a com mercial scale A company that is making some very significant inroads into storage develop ments that offer a quantum leap increase is called Polight Technologies A Cambridge University spin out it has some interesting ideas that it is claimed are capable of rev olutionising the way in which data is stored In fact its ideas could sound the death knell for some existing forms of mass storage and may even spell the end for the trusty disk drive that has been at the centre of computer technology for so many years New Technology The idea is based around a group of semiconducting glasses known as chalco genides that contain Group VI elements These exhibit some significant changes when they are illuminated by a particular form of light These can include changes in structure volume and various optical properties including the refractive index and level of light absorption As a demon stration of some of the effects that can be created it has been shown that a bi layer cantilever can be deflected up and down by exposing it to polarised light However it is the change in refractive index that is of particular importance as this can be used to enable vast amounts of data to be stored Up until now it has not been possible to use this form of optical storage commercially as a result of mater ial problems Now with the introduction of the new chalcogenides a w
60. of equilibrium is even tually reached between the charger output and the trickle charge requirement of the bat tery along with any loads formed by the car clock alarm etc A 200mA fuse near the cigar lighter plug guards against shorts The prototype was set up by connecting an ammeter in the output circuit connecting to car and mains supply and advancing the preset trimmer VRI until a current of approximately 60mA was displayed This corresponded to an output voltage of ELECTRON G ALIPER ES 56 067 CR201 0 046 Electronic digital caliper for both imperial 0 6 inches and metric 0 150mm Accuracy 0 001 Simpla touch button facility to change from metric to imperial and vice versa FROM MAINS ADAPTER 17V D C 500mA approximately 14V This value will need to be altered to suit the standing current drain from any car acces sories permanently connected to the bat tery but in practice a trickle current of around 50mA into the battery was found to be sufficient Not all cigar lighter sockets may allow such a connection so consider a direct con nection to the battery as an alternative APOLOGY We regret to say that the item Battery Discharger EPE May 2002 issue was not an original item EPE has since received an apology from Liao Jian Mei the author concerned Our thanks to the reader who notified us promptly and EPE duly apologises to the publishers of Elektor magazine who published the orig inal
61. of the Simple Audio Circuits A suitable Bulgin fused Euro style mains inlet chassis mounting plug code MK18U or FT37S together with an insulation rear tag protective cover code JK67X and line socket UL16S is listed by Maplin 0870 264 6000 or www maplin co uk They also list the 6A 200V P600D rectifier diode for one version of the Power Supply Unit code UK60Q If problems are experienced in obtaining a ferrite rod for the Crossover unit we understand from the author that one is obtainable from JAB PO Box 5774 Birmingham B44 8PJ mail order only and J Birkett 01522 520767 You will need to cut the rod down to size take care it is brittle These two firms can also supply 50g 20z reels of enamelled cop per wire for the Crossover The two printed circuit boards are available from the EPE PCB Service codes 356 PSU and 357 Crossover see page 539 Rotary Combination Lock Probably the most expensive item when purchasing components for the Rotary Combination Lock project is likely to be the heavy duty power sole noid The one in the model cost about 15 and came from RS amp 01536 444079 or rswww com and is their 12V d c standard pull action spring return type code 250 1303 They also supplied the Omron 12V d c ultra min p c b mounting relay code 369 359 The two printed circuit boards are available from the EPE PCB Service code 260 Lock and 361 Interface PLEASE TAKE NOTE L E D Sequencer
62. on the phone and TV as well 42 49 Ref TDS INFRA RED FILM 6in square piece of flexible infra red film that will only allow IR light through Perfect for converting ordinary torches lights headlights etc to infra red output using only stan dard light bulbs Easily cut to shape 6in square 15 Ref IRF2 or a 12in square for 29 95 Ref IRF2A SMOKE ALARMS Mains powered made by the famous Gent company easy fit next to light fittings power point Pack of 5 15 Ref SS23 pack of 12 24 Ref SS24 CCTV CAMERAS FROM 25 Check out our web site at www cctvstuff co uk and www home cctv co uk 14 WATT SOLAR PANELS Amorphous silicon panel fitted in an anodised aluminium frame Panel measures 3ft by 1ft with 3m leads for easy connection 3ft x 1ft solar panel 79 Ref MAG45 Unframed 4 pack 8 9W 3ft x 1ft 99 Ref SOLX 35 watts of solar power for just 99 4 panels each one 3ft x 1ft and pro ducing 8W min 13V Pack of four 99 Ref SOLX AIR RIFLES FROM LESS THAN 40 CROSSBOWS WIDE RANGE OF BB GUNS AMMO TARGETS PISTOLS REPLICA GUNS UZI MACHINE GUN REPLICAS BB REPEATERS LASER SIGHTS ELECTRIC BB GAS BB www airpistol co uk E E E L INKJET CARTRIDGES FROM JUST 3 AT I www officebits co uk oo oo POWERSAFE DEEP CYCLE BATTERIES 6V 100AH 39 EACH NEW 12V 12in SQUARE SOLAR PANEL Kevlar backed 3 watt output copper strips for easy solder connections 14 99 Ref 15P42 Pack of fo
63. only A 08701 202530 code EN55028 A post and packing charge is made on all orders under 30 The Autoswitch printed circuit board is available from the EPE PCB Service code 358 see page 539 Teach In 2002 Lab 9 Once again it s only the sensor and semiconductor devices called for in this month s Teach In 2002 Lab Work that will give some readers sourc ing grief Starting with the Nemoto NAP 7AU gas sensor compensator pair these were obtained from Maplin 0870 264 6000 or www maplin co uk code FM87U and are sold as a pair We have found two listings for the precision low off set op amp type OP177 and it can be ordered from Rapid Electronics 01206 751166 or www rapidelectronics co uk code 82 0092 or RS Components 01536 444079 or on the web at rswww com code 127 2868 Expect to pay a handling and postage charge If readers experience any difficulty in finding a local source for the 4093 quad 2 input NAND Schmitt trigger Rapid 83 0420 and the ADC0804 8 bit analogue to digital chip Maplin QQO0A or RS 411 674 they should contact the above mentioned companies The relevant code numbers are shown in brackets The Linear Technology LTC1062CN8 5th order switched capacitor low pass filter i c used in the Anti aliasing Filter Lab 9 5 appears to be listed only by RS see above code 633 880 EPE Stylopic A couple of items proved hard to find when tracking down parts for the EPE StyloPIC project The National Se
64. operation affecting the PC requires that PCLATH contains the correct value for the operation concerned Sometimes for example GOTO is used in a timing loop which might have to allow for two additional PCLATH setting instructions and this loop might lie across a page boundary Somehow these matters must be catered for in PIC programs whether they are writ ten in normal PIC code or in a high level language such as BASIC or C As with so much in programming there are diverse opinions on which is the best technique A useful strategy for instance could be 1 Assign a functionality to each of the pages which minimizes CALL and GOTO instructions across page boundaries 2 If possible provide buffer zones with no instructions near page boundaries 3 Write a first pass for the code ignoring the need to set PCLATH have it assembled and examine the listing 4 Determine where CALL and GOTO instructions cross page boundaries and where table calls or other arithmetic oper ations on PCL cross sub page boundaries 5 Readjust tables so they are complete ly contained in a sub page 6 Include PCLATH setting instructions where required 7 Repeat steps 4 5 and 6 until no fur ther corrections are required In an automatic program to do the above steps 1 2 and 3 would mostly be done by the programmer and the automat ic program would do the rest The pro grammer might have to try again if the process d
65. ply The requirements are summarised in Table and the associated notes Details of the modest current needs of the various preamplifiers were given in Part 2 of the series and the current demands of the power amplifiers are scheduled in Table 2 Dimensions and fixing arrangements for mains transformers vary and this heavy component should be mounted directly into or on the metal equipment case bottom or chassis panel A Euro style mains inlet plug with a built in fuseholder for FS1 is strongly recommended You can of course use a Separate panel mounting fuseholder if you wish see Fig 2 Mains Earth should be connected to any metal case and to the core and cladding of the transformer A solder tag bolted under one of the mains transformer mounting lugs makes a good earthing point for the mains Earth lead Interwiring details to off board compo nents are also shown in Fig 2 Leads con necting the mains transformer to the inlet plug and the p c b and any mains switch wiring should be tightly twisted to minimise external fields Keep the transformer at least 150mm 6in away from signal input wiring Toroidal transformers have a smaller external field than units with conventional cores They are the component of choice when the equipment is particularly compact and or high gain preamplifiers are used HEATSINKING Unless the current drain is to be very low say 20mA or less the regulator i c s must be bolted to a heats
66. remains at whatever value it holds at the time of the instruction It is possible to place a table anywhere in program space by setting PCLATH before the call to the table is made As explained presently the purpose of PCLATH is to set PCH for the call itself Then at the arithmetic instruction it is used again to set PCH but with an impor tant distinction The call itself only requires bits 3 and 4 of PCH to be set whereas the arithmetic instruction requires bits 0 to 4 to be set for 8K program memory devices For 4K pro gram memory devices bit 4 of PCH is ignored The program example shows how this is done Fortunately the value may be set into PCLATH for all 5 4 bits and need not be changed again until after the table has returned its value Fig 1 illustrates this process CALL AND GOTO The operation code for CALL and GOTO instructions sets 11 bits of the des tination address which is all that is needed in 2K program memory devices The addi tional bits are set from PCLATH bit 3 for AK program memory devices and bits 3 and 4K for 8K devices This is shown in Fig 2 509 LISTING 1 MOVLW 00001000 Set up for page 1 LISTING 3 MOVLW 00001011 Set up for page 1 MOVWE PCLATH sub page 3 MOVLW 1 Get second line from CALL TABLE2 second table MOVWE PORTB Display it on port B CLRF PCLATH MOVWE PCLATH sub page 0 MOVLW 2 Get third line from CALL TABLE first table MOVWE PORTB Display i
67. rou tine to talk to intelligent c d s it only uses three I O pins and although not optimised works ok I would recommend TK3 as a tutor and devel opment tool excellent value well done many thanks Thanks also to Malcolm Wiles for a very informative and for me timely article on interrupts Graham Card via email Very many thanks for the kind words and soft ware offering it looks interesting It s too long to quote in Readout but I have put the code in the PIC Tricks folder on our FTP site Regarding comparison articles that would be extremely difficult for us to do in a meaning ful manner since it would require someone to acquire and learn the various programmers that are available No one is realistically ever going to have the time to do this nor would it be cost effective in respect of the research and equip ment costs It s a nice idea and a pity we could not undertake it HIGH VOLTAGE GENERATORS Dear EPE I want to build a high voltage generator of sufficient power and voltage to kill rodents I built something in kit form some years back using a Darlington circuit which was used as a car ignition amplifier Perhaps I could follow the same tack but what I really want is a unit powered by about 6V to 12V d c storing volt age of the maximum that could be generated from this source but perhaps not exceeding 30kV until it is delivered through a short cir cuit that occurs when a rodent treads on
68. sensitivity control per channel Power handing 400W channel PCB 54x112mm Mains powered Box provided 6014KT 24 95 12 RUNNING LIGHT EFFECT Exciting 12 LED light effect ideal for parties discos shop windows amp eye catching signs PCB design allows replacement of LEDs with 220V bulbs by inserting 3 TRIACs Adjustable rotation speed amp direction PCB 54x112mm 1026KT 15 95 BOX for mains opera tion 2026BX 9 00 DISCO STROBE LIGHT Probably the most excit ing of all light effects Very bright strobe tube Adjustable strobe frequency 1 60Hz Mains powered PCB 60x68mm Box provided 6037KT 28 95 ANIMAL SOUNDS Cat dog chicken amp cow Ideal for kids farmyard toys amp schools SG10M 5 95 3 1 2 DIGIT LED PANEL METER Use for basic voltage current displays or customise to measure temperature light weight movement sound lev els etc with appropriate sensors not supplied Various input circuit designs provided 3061KT 13 95 IR REMOTE TOGGLE SWITCH Use any TV VCR remote control unit to switch onboard 12V 1A relay on off 3058KT 10 95 SPEED CONTROLLER for any common DC motor up to 100V 5A Pulse width modulation gives maximum torque at all speeds 5 15VDC Box provided 3067KT 12 95 3 x 8 CHANNEL IR RELAY BOARD Control eight 12V 1A relays by Infra Red IR remote control over a 20m range in sunlight 6 relays turn on only the other 2 toggle on off 3 oper ation ranges determined by jumpers T
69. single bipolar electrolytic Constructors interested only in hi fi applications can ignore the switching arrangements and simply connect a 100 turn 0 5mH inductor and the capacitor as shown in Fig 3a Next Month The final part will deal with speaker enclosures and include a which incorporates this month s Crossover Filter unit The construction of a simple and inex pensive oscillator and resonance detec tor which can be used to match any speaker to an enclosure and optimise performance will also be described cut arrangement With the inductor and low cost capacitor in series with the speaker response to speech frequencies is empha sised making the unit suitable for use with a communications receiver or for surveil lance work Rotary switch S1 selects the required function and the inductor is tapped to pro vide appropriate values for the crossover and speech filter CONSTRUCTION Construction of the Crossover Filter Unit is based on a small single sided print ed circuit board p c b This board is available from the EPE PCB Service code 351 The topside component layout full size copper foil master and off board wiring details are illustrated in Fig 7 Again sol der pins at the lead out points will simplify off board wiring The p c b makes provi sion for series and parallel combinations of capacitors and a wire link must be inserted high performance Low Frequency Oscilla
70. values for the second order two speaker network Inductors L are identical Capacitors C are identical 504 Table 3 Crossover Network Inductor and Capacitor Values Crossover frequency 500 1000 Hertz 13 063 0 42 80 40 26 1 8 0 9 0 6 56 28 18 1 26 0 84 4 20 13 3 6 1 8 1 2 28 14 9 4 ohm Speaker 1st Order Filter 4 ohm Speaker 2nd Order Filter 8 ohm Speaker 1st Order Filter 8 ohm Speaker 2nd Order Filter Or rOroror D O 1500 2000 2500 3000 3500 4000 4500 0 32 025 0 21 018 0 16 0 14 20 16 13 11 10 8 0 5 0 35 03 025 022 0 2 14 11 9 8 7 6 0 64 05 0 42 036 0 32 0 28 10 8 6 5 5 5 5 4 0 7 0 6 05 044 0 4 7 6 4 5 4 3 5 3 Inductance values L are given in mH millihenries Capacitor values C are given in uF microfarads See text for guidance on rounding figures up or down to nearest standard value various audio frequencies were tabulated in Part Two FILTER ORDERS The simple first order filters shown in Fig 3a and Fig 3d are perfectly suitable for domestic systems rated at up to 15W C FIRST ORDER NETWORK MID PASS ARRANGEMENT Make the reactance of inductor L and capacitor C at the centre frequency of the pass band equal to the rated speak er impedance Assume a band centre frequency of 1000Hz when the circuit is being used as a band pass filter for speech frequencies E o1 MID RANGE FIRST ORDER NETWORK THREE SPEAKER SYSTEM 1 Make inductor L1 and ca
71. will be eas ier and safer The mains and lighting cables are con nected via 3 way terminal blocks TB1 and TB2 These are soldered to the p c b and provide a convenient way of connecting leads at a later stage Likewise a 2 way block TB3 can be used to connect the mains neon indicator LP1 Alternatively the mains neon may be soldered directly to the appropriate p c b pads but before fitting the neon check which way it passes through the case if fitted from the outside you will need to attach it to the case before solder ing or screwing in its leads Finally fit IC2 into its socket checking that its notch or dot is at the correct end and taking the same anti static precautions as described earlier TESTING It is strongly recommended that the circuit board should first be tested on a separate 9V or 12V battery supply before connecting it to the mains otherwise house the circuit in its case first and return to testing later Connect a separate battery supply by clipping a pair of leads to the appropriate tracks on the circuit board Check that the correct polarity is observed The track at the top leading to IR diode D1 is the positive supply and the track at the very bottom of the p c b is the negative OV supply line If terminal pins have been fit ted to pads PI and P2 then join these together for testing IR sensor centre and diodes mount ed at one end of the p c b Switch on The relay s
72. 0 tutorials to Sound Generation Data Display and a Securit System e PIC TUTOR Board with Switches I e d s and on board programmer PIC TUTOR BOARD KIT Includes PIC16F84 Chip TOP Quality PCB printed with Component Layout and all components not ZIF Socket or Displays Included with the Magenta Kit is a disk with Test and Demonstration routines KIT 870 27 95 Built amp Tested 42 95 Optional Power Supply 3 99 ZIF Socket 9 99 LCD Display 7 99 LED Display Reprints Mar Apr May 98 3 00 set 3 SUPER PIC PROGRAMMER e READS PROGRAMS AND VERIFIES e WINDOWS SOFTWARE e PIC16C6X 7X AND 8X e USES ANY PC PARALLEL PORT e USES STANDARD MICROCHIP HEX FILES e OPTIONAL DISASSEMBLER SOFTWARE EXTRA e PCB LEAD ALL COMPONENTS TURNED PIN 29 99 SOCKETS FOR 18 28 AND 40 PIN ICs e SEND FOR DETAILED Kit 862 Power Supply 3 99 DISASSEMBLER 11 75 INFORMATION A SOFTWARE SUPERB PRODUCT AT AN UNBEATABLE LOW PRICE PIC STEPPING MOTOR DRIVER Kit 863 18 99 FULL SOURCE CODE SUPPLIED ALSO USE FOR DRIVING OTHER POWER DEVICES e g SOLENOIDS INCLUDES PCB PIC16F84 WITH DEMO PROGRAM SOFTWARE DISC INSTRUCTIONS AND MOTOR Another NEW Magenta PIC project Drives any 4 phase unipolar motor up to 24V and 1A Kit includes all components and 48 step motor Chip is pre programmed with demo software then write your own and re program the same chip Circuit accepts
73. 07 Email sales vanndraper co uk 508 Overseas readers can still obtain this discount but carriage charges vary according to country Please telephone fax email or write to Vann Draper Everyday Practical Electronics July 2002 Special Feature USING THE PIC S PCLATH COMMAND JOHN WALLER How to use PCLATH to access a PICs higher program addresses and place tables where you want them memory bank use in EPE June 2001 with particular reference to the PICI6F87x devices which contain up to 512 bytes of data memory The data mem ory is divided into banks of 128 bytes and John explained how to cope with the complexity of up to four banks In a similar way the program memory scope varies from 2K to 8K bytes depend ing on the device and is partitioned into 2048 2K byte wide pages Normally the use of the term page would apply to sec tions of data memory and program memo ry Microchip has chosen bank to apply to data memory special function and general purpose registers and has reserved the term page for program memory It is con venient here to divide pages into sub pages of 256 bytes each with eight sub pages to a page The extension of program memory across page boundaries is somewhat trans parent of no concern to the programmer but there are constraints on setting the pro gram counter which must be complied with for correct operation of the program PAGE ALLOCATION Most readers are
74. 1 Let us consider the action of just one of these gates According to AND logic out put terminal pin 3 will remain low logic 0 for all combinations of inputs at pins 1 and 2 except when both inputs go high logic 1 together In this case output terminal pin 3 also goes high Normally pin 2 is held low through resistor R8 and pin 1 is held high through R14 consequently C2a s output pin 3 is held low When C2a pin 2 is taken high through the 12 way rotary switch S1 see later both inputs are now high so pin 3 also goes high As pin 3 is fed back to pin 2 the gate becomes latched with its out put high As a result C2b s input pin 6 is also held high This gate s input pin 5 is nor mally held low through R9 and the same logic applies as with C2a so it too can be triggered when a pulse is received from switch S1 which enables C2c to be trig gered via S1 and so on through C2d Next consider what happens when a negative going logic 0 pulse is applied to IC2a pin 1 This causes output pin 3 to go low and each of the four latches IC2a to IC2d now resets collapsing as it were like a stack of cards in accordance with AND logic Everyday Practical Electronics July 2002 This reset action is triggered if switch S1 is set to any position other than the four which connect to the IC2 gate chain The pulses from these other positions control the opening and closing of electronic switches Cla
75. 1 10u BIPOLAR ELECTROLYTIC 1b A LS1 il BASS 8Q SPEAKER INPUT FROM AMPLIFIER S1 POSITIONS 1 WIDE RANGE O HIGH PASS LS2 TREBLE MID RANGE 8Q SPEAKER Fig 6 Circuit diagram for the Loudspeaker Crossover Audio Filter Enamelled copper wire Crossover only 100 turns 20 s w g 19 a w g Crossover and Filter 200 turns 22 S W g 21 a w g See Fig 4 and text Miscellaneous S1 3 pole 4 way rotary switch only two poles used SK1 SK2 4mm screw terminal post socket 2 off Printed circuit board available from the EPE PCB Service code 357 Crossover Filter multistrand and connecting wire plastic control knob speaker terminals solder pins solder etc Approx Cost 9 Guidance Only excluding speakers SPEAKERS 1 95IN 49 5mm wwe6 7Z NIS6 Z Fig 7 Crossover Audio Filter printed circuit board component layout interwiring to off board components and full size copper foil master The completed crossover is shown in the above photograph 506 Everyday Practical Electronics July 2002 in Fig 6 The first order filter serves as a basic crossover when the speaker is being used for testing or listening to hi fi equipment Switching out the Treble speaker and connecting the inductor in series with the Bass speaker gives a low pass top cut effect Connecting the capacitor in series with the speaker provides a high pass bass if capacitor Cl is a
76. 1 12 1 32 3 92 2 1 12 5 8 2 Current drain and power output measured just before the onset of clipping Everyday Practical Electronics July 2002 Regulator I C C5 1A max output Working Voltage L7806 25 L7809 25 L7812 35 L7815 35 1 To determine the transformer current rating add together the current demands of pre and power amplifiers and any ancillary equipment then increase the total by at least 25 to allow for the reactive load presented by C5 2 A bridge connected pair of TDA2003 i c s with a 4 ohm load will draw 1 7A from a 15V supply and the ratings of the rectifiers regulator and reservoir capacitor must be increased Use 1N5401 rectifiers an L78S15 regulator and a 4700uF capacitor for C5 3 For two bridge connected pairs of TDA2003 i c s in a stereo combination fit a 10000uF or two 4700uF 35V reservoir capacitor two L78S15 regulators one for each stereo series Maximum current ratings are 5A for 12V and 3A for 15V units but chips rated at more than 2A can be difficult to obtain When the current demand exceeds 2A e g when two bridge connected pairs of TDA2003 audio power amplifier modules are used in a stereo combination fit a 2A regulator to each output of the power supply and use one for each stereo channel Suppressor Capacitors The working voltage of capacitors C1 to C4 connected across the rectifier diodes should be at least four times the secondary voltage of the mains transformer Bypa
77. 4 Was 4 for 4 00 Bow only 2 00 38 283 Mixture pack of LED s All sorts of shapes and sizes and colours Pack 48 111 Vibrating motor designed for pagers amd mobile phones 20mm long x 7mm diameter Works between dV and 6V Vary small and excellent quality 2 50 3x40 way IDG sockets so you can have two hard drives munning off the same motherboard 580mm long 1 50 80 103 Floppy disk drive cable to enable the use of up to 2 floppy disk drives Has 3 x 34 way IDC sockets and 2 44 way card edge connectors mounted on a 650mm bong ribbon cable 1 50 80 104 Ribbon cable lead 450mm long with 3x 40 way IDC sockets for wee with hard dives and CD ROM s Also included is a4 pin in line socket to a4 pin in lina socket lead for internal CD ROM audio connection 2 00 36 484 MES lamp holder with two screw fixing holes for mounting Screw larminals for connection White 1 00 For Pack Of 4 56 155 KBPC3501 bridge rectifier 100V 354mp 2 50 each 48 140 PVC electrical tape 19mm wide x 0 15mm thick x 33 m tres long Flame retardant 853924 75p SEND FOR OUR FREE CATALOGUE CONTAINING EVEN MORE BARGAIN ITEMS Everyday Practical Electronics July 2002 usually around 45 00 each to buy 14 95 56 006 Brand new 12V DC tan 80 x 80 x 25mm with 10 red and black lead 2 95 WEN Supplies Dept EE The Old Grain Store Rear Cf 62 Rumbridge Street Totton Southampton 040 905 ALL PRICES INCLUDE VAT ADD EZ 2S FO
78. 75 to 120 so there s bound to be something for every one Prices include free delivery to any mainland UK address For more information contact Magnifico UK Ltd Dept EPE 12 Sussex Road Harrow HA1 4LX Tel fax 020 8891 6966 Web www magnifyingglasses co uk Email sales magnifyingglasses co uk Magfield Sensors OVER recent years we have published three constructional projects that use the FGM 3 magnetic field sensor from Speake amp Co Bill Speake the proprietor tells us that he now has a website through which you can browse the company s full range of products It can be accessed by either of the following www speakesensors co uk or www speakesensors com 483 New fechnology Update EMORY and in particular long term memory such as that supplied by disk drives tape drives and the like is a key ele ment in electronics technology Storage is being used at an ever increasing rate as software becomes more complicated and takes up more storage space Also with the growing reliance on computer technology there is a greater need to take back ups and have long term archive systems Instead of requiring disk sizes in megabytes the storage sizes will be mea sured in terabytes Whilst there is plenty of room for development using today s tech nologies new ideas will be required for years into the future Many of these new ideas are emerging even now This is a necessity as often they require many years
79. ANCE Speech coil impedance is usually mea sured at around 400Hz At this frequency the inductance of the coil has a minimal effect and its impedance is only one or two ohms more than its d c resistance As fre quency rises the inductance of the speech coil has a growing impact and impedance mounts steadily The movement of the speech coil in the magnetic field induces in it a voltage which opposes the signal voltage At the cone s resonant frequency very little energy is needed to sustain it in motion and it vibrates readily over larger distances for a comparatively small power input These larger cone excursions generate a greater opposing voltage or back e m f and speech coil impedance at resonance increases by as much as a factor of ten over its nominal value The more powerful the magnetic field the more dramatic the rise in impedance Impedance peaking at cone resonance between 30Hz and 100Hz for low fre quency speakers and the gradual rise in impedance with increasing frequency makes the response of the speaker non lin ear The power which can be fed to a speaker system falls as its impedance rises Fortunately the former can be tamed by good enclosure design and the latter can be overcome by the use of filter net works and the addition of a tweeter Care must always be taken to ensure that the rated impedance of a speaker system is not too low for the power amplifier Too low an impedance will caus
80. ATH back to its original value an essential step if the following GOTO is to work correctly The program now loops indefinitely until but ton 0 is pressed whereby execution passes to Listings 3 and 4 The operation of the second pair of Listings 3 and 4 is almost the same as the first pair The table address is still in page 1 but is in sub page 3 since OB59h 0800h 0359h and 0359h 256 3 35 or 3 rounded down to the nearest integer this may also be determined from Table 2 In Listing 4 the second line from the table 01110101 is returned and displayed and the program loops until button 1 is pressed whereby execution passes to Listing 5 TABLES BEYOND SUB PAGE 0 Listing 5 shows how a table could be placed in the 16F84 for example outside of the first 256 bytes of program memory within a page Here the table is at address 0564h or page 0 sub page 5 as set by the first two lines The next two lines call for the fourth line from the third table which returns 01100110 for display on Port B similarly to before Since the GOTO destination address is in the same page as the third table address there is no need to reset PCLATH before entering the loop which may be subse quently exited by pressing button 2 On exit the following three lines set up and execute a jump to page 3 as shown in Listing 6 Note that in Listing 6 it was sufficient to set bits 3 and 4 in Listing 5 only of PCLATH for the jump to occ
81. D Editorial Admin 01202 873872 Advertisement Manager PETER J MEW Frinton 01255 861161 Advertisement Copy Controller PETER SHERIDAN 01202 873872 On Line Editor ALAN WINSTANLEY EPE Online Internet version Editors CLIVE MAX MAXFIELD and ALVIN BROWN READERS TECHNICAL ENQUIRIES E mail techdept epemag wimborne co uk We are unable to offer any advice on the use purchase repair or modification of commercial equipment or the incorporation or modification of designs published in the magazine We regret that we cannot provide data or answer queries on articles or projects that are more than five years old Letters requiring a personal reply must be accompanied by a stamped self addressed envelope or a self addressed envelope and international reply coupons All reasonable precautions are taken to ensure that the advice and data given to readers is reliable We cannot however guarantee it and we cannot accept legal responsibility for it COMPONENT SUPPLIES We do not supply electronic components or kits for building the projects featured these can be supplied by advertisers see Shoptalk We advise readers to check that all parts are still available before commencing any project in a back dated issue ADVERTISEMENTS Although the proprietors and staff of EVERYDAY PRACTICAL ELECTRONICS take reasonable precautions to protect the interests of readers by ensuring as far as practicable that advertisements are
82. D4 removes any back e m f produced by the relay Miscellaneous T1 230V a c mains transformer p c b mounting with twin 9V 0 028A secondaries total rating 0 5VA RLA mains p c b mounting low profile relay with 12V d c 360 ohm coil and 12A 250V a c single pole change over contacts The relay height should be 19mm or less to fit inside the specified case LP1 mains neon indicator with integral resistor Printed circuit board available from the EPE PCB Service code 358 plastic case size 143mm x 82mm x 30mm 14 pin d i l socket 3 way p c b mounting screw terminal block 2 off multistrand connecting wire mains cable nylon self adhesive p c b supports 3 off solder pins solder etc excluding case Approx Cost Guidance Only 477 POWER SUPPLY A regulated mains power supply is included in the circuit diagram of Fig 1 and is made up of the components to the right of relay RLAI contacts The supply was included to simplify installation of the sys tem The main components are the mains transformer T1 bridge rectifier RECI smoothing capacitor C3 and the 12V volt age regulator IC3 The Autoswitch circuit consumes very little power and so a fully encapsulated p c b mounting mains transformer was employed The specified transformer sup plies a limited current and its secondary can be short circuited without the trans former being damaged Note that there are two separate secondary windin
83. ECTS THEORY NEWS COMMENTS POPULAR FEATURES CAL Le STRONICS Pd OO ee ss Www epemag wimborne co uk EPE Online www epemag com Projects and Circuits Cover illustration by Jonathan Robertson INFRA RED AUTOSWITCH by Max Horsey 476 Keeps work surface lights turned on only while you are near to them INGENUITY UNLIMITED hosted by Alan Winstanley 486 Velocity Detector Car Battery Trickle Charger EPE STYLOPIC by John Becker 488 Have fun with a modern interpretation of a classic musical instrument SIMPLE AUDIO CIRCUITS 3 Power Supplies Loudspeakers 500 Crossover Networks and Filters by Raymond Haigh A compendium of useful audio amplifier circuits for the experimenting constructor ROTARY COMBINATION LOCK by Thomas Scarborough 512 Pure logic and a stack of cards function enhance security Series and Features NEW TECHNOLOGY UPDATE by lan Poole 484 Holographic techniques could revolutionise computer data storage USING THE PIC S PCLATH COMMAND by John Waller 509 How to access PIC addresses beyond 2K and place tables outside the basic 256 byte block CIRCUIT SURGERY by Alan Winstanley and lan Bell 519 Bandgap Voltages More on X and Y capacitors Yaesu Battery Charger again PRACTICALLY SPEAKING by Robert Penfold 522 A practical look at interpreting component codings NET WORK THE INTERNET PAGE surfed by Alan Winstanley 527 Search Engines Tiscali 10 0 TEACH IN 2002 9 Filters
84. ELECTION FROM OUR VAST EVER CHANGING STOCKS IC s TRANSISTORS DIODES OBSOLETE SHORT SUPPLY BULK 10 000 000 items EX STOCK For MAJOR sav nGs CALL or see web site www distel co uk COMPUTER MONITOR SPECIALS Legacy products High spec genuine multysync CGA EGA VGA SVGA Mitsubishi FA3415ETKL 14 SVGA Multisync colour monitor with fine 0 28 dot pitch tube and resolution of 1024 x 768 A vari including IBM PC s in CGA EGA VGA amp SVGA modes BBC COMMODORE including Amiga 1200 ARCHIMEDES and APPLE Many features Etched faceplate text switching and LOW RADIATION MPR specification Fully guaranteed in EXCELLENT little used condition Tilt amp Swivel Base 4 75 ety of inputs allows connection to a host of computers VGA cable for IBM PC included Only 1 29 Order as CG73 External cables for other types of computers available CALL Generic LOW COST SVGA Monitors We choose the make which includes Compaq Mitsubishi IBM etc Supplied ready to run with all cables Standard RTB 90 day guarantee 15 17 69 00 79 00 Supplied in good used condition Shipping code D VIDEO MONITORS PHILIPS HCS35 same style as CM8833 attractively styled 14 colour monitor with both RGB and standard composite 15 625 Khz video inputs via SCART socket and separate phono jacks Integral audio power amp and speaker for all audio visual uses Will connect direct to Amiga and Atari BBC computers Ideal fo
85. Everyday Practical Electronics July 2002 The mapping of an infinite range of ana logue values onto the limited number of digital values is called quantisation A cir cuit called an Analogue to Digital Converter ADC is used to obtain the dig ital representation of an analogue signal ADCs come in many types and forms they are available as individual i c s but are also built into some microcontrollers To convert a digital signal to analogue we use a Digital to Analogue Converter DAC Similarly these have a variety of forms and may be built into microcontrollers We stated earlier that an 8 bit binary number gives us a range of 0 to 255 Does this mean that it would only be useful for a signal of OV to 255V The answer is no because we can scale the range of values represented by the binary number in any way we like A range of 0 to 255 could rep resent OV to 255mV in ImV steps OV to IV in 3 9lmV steps O to 1 02V in 4mV steps 10V to 25V in 0 0588V steps 3 55V to 1V in 0 01V steps and so on Note that the span of the signal represent ed by the binary number does not have to start at OV We can also represent both negative and positive numbers using our binary digits The simplest way is to designate one of the bits as the sign e g O for positive 1 for negative and use the remaining bits for the numerical value For eight bits this would give a range of 127 to 127 which again could be scaled to represent any
86. FTDZ Dual sound unit 650 R amp S SBUF E1 Vision modulator 775 WILTRON 6630B 12 4 20GHz RF sweep generator 5750 TEK 2445 150 MHz 4 trace oscilloscope 1250 TEK 2465 300 Mhz 300 MHz oscilloscope rack mount 1955 TEK TDS380 400Mhz digital realtime disk drive FFT etc 2900 TEK TDS524A 500Mhz digital realtime colour display etc 5100 HP3585A Opt 907 20Hz to 40 Mhz spectrum analyser 3950 PHILIPS PW1730 10 60KV XRAY generator amp accessories POA VARIACS Large range from stock call or see our website CLAUDE LYONS 12A 240V single phase auto volt regs 325 CLAUDE LYONS 100A 240 415V 3 phase auto volt regs 2900 sone E ret see T 2 ALL MAIL TO 18 Million Items On Line Now e o o 68 sese o Secce coo Dept eee 35 hee adhe Rd Secure ordering Pictures Information os ee gt s ornton Hea ihpin x Sooo Soone Fo s WWww distel co uk Fri 9 00 5 30 email admin distel co uk Surplus always wanted for cash 19 RACK CABINETS Europe s Largest Stocks of quality rack cabinets enclosures and accessories Over 1000 Racks from stock oats O oh This month s special 33 42 47 U High Quality All steel Rack Cabinets Made by Eurocraft Enclosures Lid to the highest pos sible spec rack features all steel construction with removable side front and back doors Front and back doors are hinged for easy access and all lt ZS lockable with five secure 5 lever barrel lock
87. Fig 9 7 Geiger Muller tube construction www bre co uk radon links html This is the Building Research Establishment and the page referred to has links to bodies such as the DETR Department of Transport and the Regions Astronauts receive large doses of radia tion ranging from solar X rays and solar particles to cosmic rays Electronic equip ment in space is very susceptible to radia tion and only radiation hardened electronics can be used The Galileo spacecraft orbiting Jupiter has encountered high levels of radiation during its tour of Jupiter s moons and as the spacecraft has become older increasing numbers of faults have been occurring due to radiation damage It has apparently endured more than twice its designed amount of radiation and is still operational The two major areas where we are likely to hear of or encounter radiation are nuclear power stations and in medicine Nuclear power stations are widespread in the world and in some countries such as Belgium and France they produce as much as 69 percent of the country s electricity In Britain this is around 20 percent Power stations can be highly dangerous and most of us will remember Chernobyl where caesium released by the explosion settled on grazing land in the UK and entered the human food chain mainly via sheep The other worry is the disposal of waste which may remain radioactive for thou sands of years It is ironic that nuclear power would appear to
88. For non special ists there s even a graphical glossary that clearly illustrates technical terms The author goes under the hood and shows step by step how to create a socket 7 Pentium and non intel chipsets and a Slot 1 Pentium Il computer covering What first time builders need to know How to select and purchase parts How to assemble the PC How to install Windows 98 The few existing books on this subject although badly outdated are in steady demand This one delivers the expertise and new technology that fledgling computer builders are eagerly looking for 224 pages large format Rol E Cla yam 21 99 184 pages 12 95 PIC YOUR PERSONAL INTRODUCTORY COURSE SECOND EDITION John Morton Discover the potential of the PIC micro controller through graded projects this book could revolutionise your electronics construction work A uniquely concise and practical guide to getting up and running with the PIC Microcontroller The PIC is one of the most popular of the microcontrollers that are transforming electronic project work and product design Assuming no prior knowledge of microcontrollers and introducing the PIC s capabilities through simple projects this book is ideal for use in schools and col leges It is the ideal introduction for students teachers technicians and electronics enthusiasts The step by step explanations make it ideal for self study too this is not a reference book you star
89. Light DEC 01 East Ferndown Dorset BH22 9ND Tel 01202 873872 Fax 01202 874562 oa e E mail orders epemag wimborne co uk On line Shop www epemag Main wimborne co uk shopdoor htm Cheques should be crossed and made payable to K PIC Polywhatsit Digital Everyday Practical Electronics Payment in sterling only Analogue NOTE While 95 of our boards are held in stock and are dispatched within Forever Flasher JAN 02 seven days of receipt of order please allow a maximum of 28 days for delivery overseas readers allow extra if ordered by surface mail Back numbers or photostats of articles are available if required see the Back Versatile Benen Power Sunni Issues page for details X PIC Spectrum Analyser FEB 02 334 71 3 Boards can only be supplied on a payment with order basis Guitar Practice Amp 336 5 39 PIC Virus Zapper MAR 02 337 PROJECT TITLE Order Code RH Meter 338 EPE Icebreaker PCB257 programmed MAR 00 k PIC Mini Enigma Software only PIC16F877 and floppy disc Set only 22 99 K Programming PIC Interrupts Software onl APR 02 A Micro PICscope APR tan 259 4 99 PIC Controlled Intruder Alarm i Garage Link Transmitter 261 amp PIC Big Digit Display MAY 02 Receiver 262 ser 5 87 Washing Ready Indicator Versatile Mic Audio Preamplifier MAY 00 3 33 a el eae PIR Light Checker 3 17 TBA820M Multi Channel Transmission System Transmitter
90. M broadcasting and want a good basic circuit to experiment with 12 18VDC PCB 44x146mm 1028KT 22 95 AS1028 34 95 15 WATT FM TRANSMITTER PRE ASSEMBLED amp TESTED Four transistor based stages with Philips BLY 88 in final stage 15 Watts RF power on the air 88 108MHz Accepts open dipole Ground Plane 5 8 J or YAGI antennas 12 18VDC PCB 70x220mm SWS meter needed for alignment 1021KT 99 95 SIMILAR TO ABOVE BUT 25W Output 1031KT 109 95 STABILISED POWER SUPPLY 2 30V 5A As kit 1007 above but rated at 5Amp Requires a 24VAC 5A transformer 1096KT 27 95 MOTORBIKE ALARM Uses a reliable vibration sensor adjustable sensitivity to detect movement of the bike to trigger the alarm amp switch the output relay to which a siren bikes horn indicators or other warning device can be attached Auto reset 6 12VDC PCB 57x64mm 1011KT 11 95 Box 2011BX 7 00 CAR ALARM SYSTEM Protect your car from theft Features vibration sensor courtesy boot light voltage drop sensor and bonnet boot earth switch sensor Entry exit delays auto reset and adjustable alarm duration 6 12V DC PCB 47mm x 55mm 1019KT 11 95 Box 2019BX 8 00 PIEZO SCREAMER 110cB of ear piercing noise Fits in box with 2 x 35mm piezo elements built into their own resonant cavity Use as an alarm siren or just for fun 6 9VDC 3015KT 10 95 COMBINATION LOCK Versatile electronic lock comprising main circuit amp separate keypad for remote openin
91. MAV 6 1Gb laptop 12 7 mm H New 98 00 2 2 TOSHIBA MK1614GAV 18 Gb laptop 12 mm H New 149 95 2 to 3 2 conversion kit for Pc s complete with connectors 15 95 3 2 COMPAQ 313706 B21 IBM 9 gb ULT SCSI3S New 199 00 3 FUJI FK 309 26 20mb MFM I F RFE 59 95 3 CONNER CP3024 20 mb IDE I F or equiv RFE 59 95 3 CONNER CP3044 40 mb IDE I F or equiv RFE 69 00 3 QUANTUM 40S Prodri ve 42mb SCSI I F New RFE 49 00 5 MINISCRIBE 3425 20mb MFM I F or equiv RFE 49 95 5 SEAGATE ST 238R 30 mb RLL I F Refurb 69 95 5 CDC 94205 51 40mb HH MFM I F RFE tested 69 95 5 HP 97548 850 Mb SCSI RFE tested 99 00 5 HP C3010 2 Gbyte SCSI differential RFE tested 195 00 8 NEC D2246 85 Mb SMD interface New 99 00 8 FUJITSU M2322K 160Mb SMD I F RFE tested 195 00 8 FUJITSU M2392K 2 Gb SMD I F RFE tested 345 00 Many other floppy amp H drives IDE SCSI ESDI etc from stock see website for full stock list Shipping on all drives is code C TEST EQUIPMENT amp SPECIAL INTEREST ITEMS MITSUBISHI FA3445ETKL 14 Ind spec SVGA monitors 245 FARNELL 0 60V DC 50 Amps bench Power Supplies 995 FARNELL AP3080 0 30V DC 80 Amps bench Suppy 1850 KINGSHILL CZ403 1 0 50V DC 200 Amps NEW 3950 1kW to 400 kW 400 Hz3 phase power sources ex stock POA IBM 8230 Type 1 Token ring base unit driver 760 Wayne Kerr RA200 Audio frequency response analyser 2500 INFODEC 1U 24 port RJ45 network p
92. MHz2 preprogrammed see text IC2 TLC7524 digital to analogue converter IC3 78L05 5V 100mA voltage regulator IC4 LM13600 transconduc tance amplifier IC5 L272 dual power op amp Miscellaneous S1 min s p d t switch S2 min push to make switch SK1 3 5mm mono jack socket see text TB1 1mm terminal pins or pin header optional X1 20MHz crystal Printed circuit board available from the EPE PCB Service code 359 8 pin d i l socket 16 pin d i l socket 2 off 40 pin d i l socket stylus see text loud speaker or headphones see text case to suit See text supports for p c b see text connecting wire solder etc 25 Approx Cost Guidance Only excluding speaker case amp batts steel based keyboard of the Stylophone Readers using the ready made board from the EPE PCB Service should fare better in this respect since the boards are roller tinned unlike the bare copper boards that usually result from making your own Nonetheless whilst you will periodical ly get carried away with rapid glissandos and staccato keying try not to dig holes into the keyboard pads and certainly avoid contact with the connections leading from Everyday Practical Electronics July 2002 them to the PIC Probably though a touch of the soldering iron will repair minor damage SOFTWARE HIGHLIGHT It was mentioned earlier that the tuning accuracy of the StyloPIC surpasses that for any PIC controlled music
93. NENTS ROTARY COMBINATION LOCK See R1 R3 1k 2 off R2 150k SHOP R4to R14 22k 110 TALK R15 1509 1W page see text All 0 25W 5 carbon film except R15 Resistors Capacitors C1 10u sub min radial elect C2 1000u sub min radial elect 16V see text Semiconductors D1 green l e d 3mm D2 ultrabright red l e d 3mm 1N4148 signal diode 4 off D7 1N4001 50V 1A rect diode D8 1N5401 100V 3A rect diode TR1 2N3819 f e t transistor TR2 2N2646 u j t transistor TRS BUZ11 power MOSFET IC1 4066 or 4016 quad bilateral switch IC2 4081 quad AND gate D3 to D6 Miscellaneous S1 1 pole 12 way rotary switch p c b mounting X1 Solenoid standard pull action spring return 12V d c Printed circuit board available from the EPE PCB Service code 360 knob and dial for switch S1 24 pin d i l socket 14 pin d i l socket 2 off connecting wire solder pins solder etc Finally 1 e d D1 is provided to test rotary switch S1 A test lead can be connected between the anode a of the 1 e d and any position of S1 row B The switch is then turned until D1 pulses This is very helpful in setting up the circuit more later CONSTRUCTION Begin construction by making modifica tions to the rotary switch S1 to provide full and smooth 360 rotation Without this the switch would fail to give the feel of a genuine rotary combination lock although the circuit would still w
94. OR AN IDEA We have collated 140 business manuals that give you information on setting up different businesses you peruse these at your leisure using the text editor on your PC Also included is the certificate enabling you to reproduce and sell the manuals as much as you like 14 Ref EP74 ANICS CO2 GAS POWERED PISTOL Russian handheld pistol powered by Sparklets CO2 cylinders give approx 70 shots fires steel BB Pistol 58 22 Ref AGA101 tub of 1 500 BB shot 5 10 Ref A1015 pack of 5 CO2 cartridges 3 50 Ref GAS5 33 KILO LIFT MAGNET Neodynium 32mm diameter with a fixing bolt on the back for easy mounting Each magnet will lift 33 kilos 4 magnets bolted to a plate will lift an incredible 132 kilos 15 Ref MAG33 Pack of 4 just 39 Ref MAG33AA BSA METEOR AIR RIFLE UK made 22 rifle top quality profes sional air rifle 84 15 Ref BSAMET 500 Lazapell pellets 5 Ref LAZAPELL MAMOD 1313 TE1A TRACTION ENGINE Attractive working model of traditional steam engine 85 Ref 1313 MAMOD STEAM ROADSTER white magnificent working steam model car 112 Ref 1319 MAMOD STEAM WAGON Working model steam wagon finished in blue 112 Ref 1318 Brown version with barrels 122 Ref 1450 POCKET SPY MONOCULAR Clever folding monocular with 8 x 21 magnification made by Helios with case 14 99 Ref MONOC KEVLAR BRITISH ARMY HATS Broken or missing straps hence just 8 each Ref KEV99 CCTV SYSTEMS 24 99 Co
95. PIC based projects published in these issues www adobe com acrobat VOL 2 CONTENTS BACK ISSUES July 1999 to December 1999 all the projects Order on line from features news Us etc from all six issues Note No advertisements www epemag wimborne co uk shopdoor htm are included PIC PROJECT CODES All the available codes for the or www epemag com USA prices PIC based projects published in these issues or by phone Fax E mail or Post VOL 3 CONTENTS Be eee a ec Gee Gc si Ge 1 BACK ISSUES January 2000 to June 2000 all the projects features BACK ISSUES MINI CD ROM ORDER FORM news Us etc from all six issues PIC PROJECT CODES All the available codes for the PIC based projects published in these issues VOL 4 CONTENTS l l l 1 Please send me quantity BACK ISSUES CD ROM VOL 1 l Please send me quantity BACK ISSUES CD ROM VOL 2 Please send me tity BACK I ES CD ROM VOL 3 BACK ISSUES July 2000 to Dec 2000 all the projects features es ENOG quan ee news lUs etc from all six issues PROJECT CODES All the available i Please send me quantity BACK ISSUES CD ROM VOL 3 codes for the programmable projects in these issues 1 Please send me quantity BACK ISSUES CD ROM VOL 5 l l l l l l l l l VOL 5 CONTENTS Please send me quantity BACK ISSUES CD ROM VOL 6 BACK ISSUES January 2001 to June 2001 all the projects features news IUs etc f
96. Penfold This book is primarily aimed at beginners and those of limited experience of electronics Chapter 1 covers the basics of analogue and digital multimeters discussing the relative merits and the limitations of the two types In Chapter 2 various methods of component checking are described including tests for transistors thyristors resis tors capacitors and diodes Circuit testing is covered in Chapter 3 with subjects such as voltage current and continuity checks being discussed In the main little or no previous knowledge or experi ence is assumed Using these simple component and cir cuit testing techniques the reader should be able to con fidently tackle servicing of most electronic projects Order code BP239 4 49 DIGITAL GATES AND FLIP FLOPS lan R Sinclair This book intended for enthusiasts students and techni cians seeks to establish a firm foundation in digital elec tronics by treating the topics of gates and flip flops thor oughly and from the beginning Topics such as Boolean algebra and Karnaugh map ping are explained demonstrated and used extensively and more attention is paid to the subject of synchronous counters than to the simple but less important ripple counters No background other than a basic knowledge of elec tronics is assumed and the more theoretical topics are explained from the beginning as also are many working practices The book concludes with an explanation of microprocessor tec
97. R P amp P 487 Constructional Project STYLOPIC JOHN BECKER Have fun with a modern interoretation of a classic musical instrument OLF Harris is well known these days for his concern for sick animals Back in the 1970s and later though he was popular as an entertainer who would delight his audience by amongst many other activities playing the didgeridoo wobble board and the Stylophone The latter was a compact hand held electronic musical instrument having a built in keyboard which was acti vated by an electrically conductive stylus The EPE StyloPIC pays homage to this classic design which is now relegated to the depths of history and enthusiast s web sites although we know some readers still have the real thing and second hand ones can still be found It is really simple in its concept yet remarkably fun to play HISTORY Some of you familiar with the original Stylophone can be forgiven for perhaps thinking that Rolf Harris actually invented this superb little instrument In fact his involvement was purely promotional but this was to prove crucial to the Stylophone s success The Stylophone came about as a result of a certain Brian Jarvis having been asked to repair his young niece s toy piano Not only did he do so but added a modification that led to the idea of a completely new hand held electronic instrument RAE Y Cre pid es Ft So Rolf and the Stylophone The greatest lit
98. SE PRINT to pay for overseas postage l l ADDRESS s n nn nnannnnnnnnnnnnnnnnnnnnmEnnmmEEmEmnEmMEEmEmmEmMEEmEmEmMEmMEmEEmMEmEE Price PER ESM PRINTED MANUAL l l Postal Region Surface Air l l 2 nnu 2u 2 22 2n 2n nnn nunn nnn nnn nunnu nun nnn EnEn EnNEEmmE Mainland UK FREE l I Scottish Highlands l POSTCODE 2 c2nstiedecsuad ax UK Islands amp Eire 7 each o l Europe EU 23 each j SIGNATURE 2220022466000 24 a a a a a a re aae ea a eTa Europe Non EU 23 each 30 each i aes USA amp Canada 28 each 39 each l _ enclose cheque PO in UK pounds payable to Wimborne Publishing Ltd Far East amp Australasia e35 each 43each l _ Please charge my Visa Mastercard Amex Diners Club Switch Switch Issue No Rest of World 28 each 52each I I I I the world Each ESM weighs about 4kg when packed a ai e e a a E A a ey i fo te fk i yl D i a E i a mem cd
99. Shortwave Loop Aerial m Club Visa or Switch XK Digitimer Main Board R F Board Perpetual Projects Uniboard 2 Card No SEPP eee L E D Flasher Double Door Buzzer Perpetual Projects Uniboard 3 Card Exp Date Loop Burglar Alarm Touch Switch Door Light and Solar Powered Rain Alarm L E D Super Torches Red Main Signature Brg boas NOTE You can also order p c b s by phone Fax Email or via our X Sync Clock Driver Internet site on a secure server Water Monitor http Awww epemag wimborne co uk shopdoor htm Time Delay Touch Switch X PIC Magick Musick cheque PO in sterling only to Everyday Practical Electronics July 2002 539 WHETHER ELECTRONICS IS YOUR HOBBY OR YOUR LIVELIHOOD YOU NEED THE MODERN ELECTRONICS MANUAL and the ELECTRONICS SERVICE MANUAL THE MODERN ELECTRONICS MANUAL CD ROM VERSION ONLY a At a ed ia a The essential reference work for everyone studying electronics Over 800 pages In depth theory Projects to build Detailed assembly instructions Full components checklists Extensive data tables Manufacturers web links Easy to use Adobe Acrobat format Clear and simple layout Comprehensive subject range Professionally written Regular Supplements EVERYTHING YOU NEED TO GET STARTED AND GO FURTHER IN ELECTRONICS The revised CD ROM edition of the Modern Electronics Base Manual MEM contains practical easy to follow information on the followin
100. Simulator CD ROM Clive Max Maxfield and Alvin Brown This follow on to Bebop to the Boolean Boogie is a multimedia extravaganza of information about how computers work It picks up where Bebop left off guiding you through the fascinat ing world of computer design and you ll have a few chuckles if not belly laughs along the way In addition to over 200 megabytes of mega cool multimedia the CD ROM contains a virtual microcomput er simulating the motherboard and standard computer peripherals in an extremely realistic manner In addition to a wealth of technical information myriad nuggets of triv ia and hundreds of carefully drawn illustrations the CD ROM contains a set of lab experiments for the virtual microcomputer that let you recreate the experiences of early computer pioneers If you re the slightest bit inter ested in the inner workings of computers then don t dare to miss this Over 800 pages in Adobe Acrobat format 21 95 including VAT and p amp p Order code BEB2 CD ROM ELECTRONICS MADE SIMPLE lan Sinclair Assuming no prior knowledge Electronics Made Simple presents an outline of modern electronics with an empha sis on understanding how systems work rather than on details of circuit diagrams and calculations It is ideal for students on a range of courses in electronics including GCSE C amp G and GNVQ and for students of other subjects who will be using electronic instruments and
101. VAT Multiple User 34 plus VAT UK and EU customers add VAT at 17 5 to plus VAT prices Electronics Hobbyist Compendium Toal and Golfering Campenient Trating OFtiftoscope asics DIGITAL WORKS 3 0 i oe FREE BOOK eee et er WITH TEACH IN Coie 2000 CD ROM O 2 ee project Digital Works Version 3 0 is a graphical design tool that enables you to construct digital logic circuits and analyze their behaviour It is so simple to use that it will take you less than 10 minutes to make your first digital design It is so powerful that you will never outgrow its capability Software for simulating digital logic circuits e Create your own macros highly scalable Create your own circuits components and i c s Easy to use digital interface Animation brings circuits to life Vast library of logic macros and 74 series i c s with data sheets e Powerful tool for designing and learning Hobbyist Student 45 inc VAT Institutional 99 plus VAT Institutional 10 user 199 plus VAT Site Licence 499 plus VAT ELECTRONIC COMPONENTS PHOTOS A high quality selection of over 200 JPG images of electronic components This selection of high resolution photos can be used to enhance projects and presentations or to help with training and educational material They are royalty free for use in commercial or personal printed projects and can also be used royalty free in books catalogues magazine article
102. Vol 31 No 7 Piy oats zi ii E Weg tak we vd a nape eS res T he l iat Lake bull af H 3 a en JY dasa f B in ti iN Ili 5 E t a ee 1 p FM A A f ha a TA i5 284s 680 11 lig olNseags Printed in thea UK http www epemag wimborne co uk Copyright 2001 Wimborne Publishing Ltd Allen House East Borough Wimborne Dorset BH21 1PF UK and Maxfield amp Montrose Interactive Inc PO Box 857 Madison Alabama 35758 USA All rights reserved WARNING The materials and works contained within EPE Online which are made available by Wimborne Publishing Ltd and Maxfield amp Montrose Interactive Inc are copyrighted You are permitted to make a backup copy of the downloaded file and one 1 hard copy of such materials and works for your personal use International copyright laws however prohibit any further copying or reproduction of such materials and works or any republication of any kind Maxfield amp Montrose Interactive Inc and Wimborne Publishing Ltd have used their best efforts in preparing these materials and works However Maxfield amp Montrose Interactive Inc and Wimborne Publishing Ltd make no warranties of any kind expressed or implied with regard to the documentation or data contained herein and specifically disclaim without limitation any implied warranties of merchantability and fitness for a particular purpose Because of poss
103. a tion where X rays and nuclear particles striking a special screen produce flashes of light These flashes are extremely faint but can be amplified using a photomulti plier tube One of the most common scin tillation materials is sodium iodide others include zinc sulphide anthracene and terphenyl SILICON The photomulti plier is a device in which an incoming photon causes an electron to be emitted from a surface this is accelerated towards a cath ode at say 100V potential When the electron hits the cathode it releases many more elec trons which are then accelerated to another cathode at say 200V and so on A typical photomultiplier may have 10 cathodes The resulting current at the final electrode is many times more than one electron and can be detected Fig 9 8 shows a schematic diagram of a scintillation detector A third method is to use semiconductors sometimes known as lithium drifted sili con detectors Germanium is sometimes used Fig 9 9 shows a diagram of such a device It consists of three layers of doped silicon a p type layer facing the radiation to be sensed an intrinsic zone and an PHOTONS RELEASED BY RADIATION CURRENT OUTPUT PHOTOMULTIPLIER CRYSTAL Fig 9 8 Scintillation detector LITHIUM DRIFTED SILICON INTRINSIC LAYER nY EE SILICON Fig 9 9 Lithium drifted sensor n type layer The outer surface of the p type layer is coated with a thin gold layer to act as an
104. a technique hitherto unpublicised through EPE Apart from the PIC microcontroller there are only three active integrated cir cuits a waveform converter an envelope shaper and an amplifier The circuit dia gram in Fig l shows the detailed connec tions between the StyloPIC s keyboard and the microcontroller IC1 along with the waveform converter C2 and the simple regulated power supply derived via IC3 The envelope shaper and amplifier are dis cussed later referring to Fig 2 The keyboard contacts are formed on the printed circuit board p c b in the style of a 25 note keyboard plus an additional mode change contact which causes a change in the tonal quality of the notes produced All contacts are connected to individual inputs of the PIC16F877 microcontroller Note that in Fig 1 the keyboard notation is shown in the order best suited to illus trating the PIC s port connections in an appropriate visual order On the p c b of course the keyboard connections are in the correct musical order Everyday Practical Electronics July 2002 O 9V O 5V NC TO C6 O TO D2 O O OV RAO ANO RA1 AN1 VE RA2 AN2 VREF RA3 AN3 VREF RA4 TOCK1 REO AN5 RD OSC1 CLKIN OSC2 CLKOUT IC1 PIC16F877 20P VE OSO T1CKI RCO 1 T10SI CCP2 RC1 CCP1 RC2 SCK SCL RC3 SDI SDA RC4 SDO RC5 TX CK RC6 RX DT RC7 PGCLK RB6 PGDA RB7 PSPO RDO PSP1 RD1 PSP2 RD2 PSP3 RD3 PSP4 RD4 PSP5 RD5 PSP6 RD6
105. actual range of voltages or currents Other ways of representing negative numbers in digital circuits and computers are in use such as two s complement but a discussion of these is outside the scope of this series As this series in mainly concerned with getting data from sensors we will look at the ADC in detail however similar con cepts such as resolution apply to DACs ADC CHARACTERISTICS In Fig 9 1 are shown a schematic symbol of an ADC and the signals typically associ ated with it There is the analogue input the n bit digital output a reference voltage which may be fixed for some ADCs and a clock or start conversion control which may not always be present START CONVERT CLOCK ANALOGUE SIGNAL DIGITAL SIGNAL n BITS Fig 9 1 Signals associated with an ADC The example shows parallel digital out put but some converters output the digital data in serial form The ADC converts the range of voltages between OV and the ref erence voltage Vppp known as the full scale range FSR into a binary number 0 to 27 1 Obtaining an accurate stable with time and temperature and low noise voltage reference is quite difficult but fortunately Everyday Practical Electronics July 2002 such references are often built in to ADC chips If not separate it Digital Chatput voltage reference i c s 110 are available for this purpose Output codes other 4 100 than binary e g G
106. age at IC2c pin 10 is near pos itive then TR1 and the relay should switch on Failure at this point suggests that the transistor may be the wrong way round or 479 Q Hole for neon Hole for LED 15mm Slot for sensor 15mm Hole for LED Slot for cables p w Suggested drilling and component positioning details for the case lid the wrong type etc You can check the oper ation of the relay by shorting together the two right hand pins c and e of TR1 This should trigger the relay CASING UP A neat white plastic case measuring 140mm x 80mm x 30mm was used in the prototype as shown in the photographs Decide which of the two halves will be used to house the circuit If required for a kitchen unit it is best to fit the p c b in the lid i e the side where you can see the lid retaining screws The base of the case can be fastened to the underside of a kitchen cupboard by means of one or two small wood screws Begin case preparation by drilling holes for these screws in the base of the case Turning your attention to the lid cut a slot in the end for the sensor IC1 The use of a slot at the side of the case ensures that the IR beam cannot be received from the rear of the l e d s or by reflections inside the case If you change the design do ensure that this point is observed other wise use large amounts of Blu Tack to pro tect the sensor from stray reflections Now drill two holes for the IR l e d
107. aie AL en poe oe H Bag FE a 5 Deae A current cover date each In pectrum nterface Dis ctober X Using PICs and Keypads Software only issue to current cover date X PIC Toolkit TK3 software Nov 01 is on CD ROM The 3 5 Ice Alarm inch disks are 3 00 each UK the CD ROM is 6 95 UK Add 50p each for overseas sur Graphics L C D Display with PICs Supp face mail and 1 each for airmail All are available from the EPE PCB Service All files can Using the LM3914 6 L E D Bargraph Drivers be downloaded free from our Internet FTP site ftp ftp epemag wimborne co uk Multi purpose Main p c b Relay Control aen oi Sonne cny EPE PRINTED CIRCUIT BOARD SERVICE poe ee a Order Code Project Quantity Price Trans Remote 294 Rec Relay 295 EPE Snug bug Heat Control for Pets APR 01 296 6 50 Intruder Alarm Control Panel Main Board 297 6 97 External Bell Unit 298 4 76 Camcorder Mixer MAY 01 299 6 34 PIC Graphics L C D Scope 300 5 07 Hosepipe Controller JUNE 01 301 Magfield Monitor Sensor Board Dummy PIR Detector 303 PIC16F87x Extended Memory Software only Stereo Surround Sound Amplifier JULY 01 Perpetual Projects Uniboard 1 Solar Powered Power Supply amp Voltage Reg TE Eve ryd ay D MSF Signal Repeater and Indicator VISA peeti e aah Practical Electronics gt Meter Board m K PIC to Printer Interface E MasterCard Amex Diners Lead Acid Battery Charger AUG 01 H ens ae
108. al networks These allow the intelligent sensor to per form tasks that normal microcontrollers cannot Examples include detecting and sometimes repairing or ignoring faults in sensors performing difficult signal analysis and actually recognizing different signals We will be discussing intelligent sensors next month ANY NUMBER YOU LIKE A numerical value held in a digital cir cuit consists of a binary number with a fixed number of digits bits For example if we have eight bits we can have binary numbers ranging from 00000000 to 11111111 0 to 255 in decimal We have a specific maximum and mini mum value 0 and 255 in this case and we also have a finite number of possible differ ent values 256 in this case This limits the step size in moving from one possible value to the next for example starting at two the next possible value is three Compare this with an analogue signal We would also usually have a fixed maxi mum and minimum possibly set by the supply voltage or the characteristics of a sensor but the number of possible values is effectively infinite For example starting at 2 0V we could step to 2 1V 2 01V 2 001V 2 0001V and so on There are practical limits of course due to how small a step we could either control or detect but from the perspective of an ideal circuit the number of possible analogue values is infinite whereas even for an ideal digital circuit it is specifically limited
109. ammer s dream when compared to a PIC Peter Hemsley via email That s useful Peter thanks AVRs that s another story A while ago we tried readers on an Atmel microcontroller design and no one was significantly interested Also despite AVRs periodically being discussed in Readout there s not a great deal of interest com ing in on correspondence We have therefore concluded that PICs which do have a good fol lowing are the microcontroller that we should principally support PIC SHIFT REG AND L C D Dear EPE Thanks to John Becker for all his hard work in producing TK3 There are many expensive pro grammers and tutors etc that fall far short of what TK3 will do a confusing minefield for people who wish to start using PICs How about a comparison feature in EPE I have used TK3 with John s excellent PIC Tutorial text downloaded with the TK3 software with a bit of thought most tutorial examples can be run on the 7K3 board I found ASM easier to pick up this way than Basic My own projects are being slowly thought out worked out and programmed The splendid Teach In series is helping me with a weather station pro ject and an inverter project is also under way Both have small programs that need only a 16F84 I did not want to use waste an F87x or buy a serial l c d too dear for alphanumerics so I extended a routine for 8 bit shift registers I developed added some of your l c d bits and ended up with a
110. an expensive affair new business entries pay 299 per year to have their web site listed in Yahoo Entry into the ODP is free If you search Yahoo but fail to find a result in its directory Yahoo will politely offer you more results gleaned from the rest of the Internet courtesy of Google This is typical of the way in which major search engine databases are used to feed results into other web sites such as AOL Click the Directory tab on Google and you will see the similarity to the ODP For a Few Dollars More This month I highlight some other useful search tools that Google has to offer Not only can Google search web pages but it can also hunt down images sim ply click the Images tab on the Google main page then enter a search phrase Google Images will return thumbnails of all the relevant images it finds on the web It is not quite clear why a microscopic close up of a creepy crawly should appear under a list ing of CMOS chip but there you a Stuck for an answer to some thing Google Answers is a new mentite beta development whereby you can actually commission a little research to help you answer a thorny problem Presently Google Answers is hosted at https answers google com answers main For a small fee you decide how much Google researchers promise to supply a paragraph or more of information that answers your question as well as links to websites that can provide more material The more you bid the quic
111. and IClb Their control inputs are normally held low via resistors R4 and R6 and their gate paths remain open very high impedance When either of them receives a pulse from switch S1 the respective gate path closes causing IC2a pin to be pulled low via diode D3 or D4 so resetting the C2 gate chain If it is IC1b that is triggered the nega tive going pulse generated at the junction of R7 and IC1b pin 3 is used to activate the Interface alarm discussed later However ICla is not connected to the alarm con troller and this allows one switch position to be used as a Reset digit to close the lock after it has been opened as well as six dig its to trigger an alarm in the case of aim less turning of the dial Diode D5 in C2d s feedback path pre vents the possibility of a brief positive going pulse from S1 reaching the gate g of transistor TR3 When the third digit of the 4 digit code has been set by switch S1 IC2c pin 9 goes high as does pin 12 of IC1d causing this bilateral switch to close This means that UNIT R1 INTERFACE switch IClc is now potentially able to con duct When IClc s control pin 6 goes high this causes a high pulse at ICld pin 11 This pulse may also be sent to the Interface unit as a Duress signal The Duress switch position may either replace the 4th digit in the 4 digit sequence or add a Sth digit to the 4th Thus someone who knows that this is a 4 digit system would not no
112. and besides one may not want this to be cancelled until help has arrived Switch S1 is a miniature pushbutton Everyday Practical Electronics July 2002 Finally l e d s D2 and D3 are provided so as to give a visual indication of whether a relay has closed or not A green l e d lights on an Alarm pulse and a red 1 e d on Duress Remember the Alarm input is inhibit ed as long as capacitor C3 retains a cer tain charge and will not work while inhibited INTERFACE CONSTRUCTION Details of the topside component layout of the Interface p c b together with the underside tracking details are shown in Fig 6 This board is available from the EPE PCB Service code 361 First solder in position the link wires solder pins and the 14 pin d i l socket then the resistors diodes and l e d s con tinuing with the capacitors and transistors IC1 is a CMOS device and anti static pre cautions are again advised Be careful to observe the correct orienta tion of the electrolytic capacitors and the transistors diodes and the i c Switch S1 is of the kind that has two commoned terminals at each side It should INTERFACE SETTING UP As the circuit stands when an Alarm pulse is received ICla s input at pin 6 is inhibited for about half an hour after the alarm has ceased sounding This period may be altered by changing the value of C3 see earlier Beyond this the only setting up that is required is the adjustment of the tim
113. and can be fdisked formatted amp booted Supplied BRAND NEW fully tested and guar anteed For full data see featured item on website Order as QG36 100 s of applications inc firewall routers robotics etc ONIY 99 00 0 14 59 00 Unless marked NEW items in this section are pre owned HP6030A 0 200V DC 17 Amps bench power supply 1950 Intel SBC 486 125C08 Enhanced Multibus MSA New 1150 Nikon HFX 11 Ephiphot exposure control unit 1450 PHILIPS PM5518 pro TV signal generator 1250 Motorola VME Bus Boards amp Components List SAE CALL POA Trio 0 18 vdc linear metered 30 amp bench PSU New 550 Fujitsu M3041R 600 LPM high speed band printer 1950 Fujitsu M3041D 600 LPM printer with network interface 1250 Siemens K4400 64Kb to 140Mb demux analyser 2950 Perkin Elmer 299B Infrared spectrophotometer 500 Perkin Elmer 597 Infrared spectrophotometer 3500 VG Electronics 1035 TELETEXT Decoding Margin Meter 3250 LightBand 60 output high spec 2u rack mount Video VDA s 495 Sekonic SD 150H 18 channel digital Hybrid chart recorder 1995 B amp K 2633 Microphone pre amp 300 Taylor Hobson Tallysurf amplifier recorder 750 ADC SS200 Carbon dioxide gas detector monitor 1450 BBC AM20 3 PPM Meter Ernest Turner drive electronics 75 ANRITSU 9654A Optical DC 2 5G b waveform monitor 5650 ANRITSU ML93A optical power meter 990 ANRITSU Fibre optic characteristic test set POA R amp S
114. and less costly to build yet far more efficient This particular design was developed at the Atomic Energy Commission of NEGEV in Israel 10 set Ref F CVL1 VOICE SCRAMBLER PLANS Miniature solid state system turns speech sound into indecipherable noise that cannot be under stood without a second matching unit Use on telephone to prevent third party listening and bugging 6 set Ref F VS9 PULSED TV JOKER PLANS Little handheld device utilises pulse techniques that will completely disrupt TV picture and sound Works on FM too Discretion advised 8 set Ref F TJ5 BODYHEAT TELESCOPE PLANS Highly directional long range device uses recent technology to detect the presence of living bodies warm and hot spots heat leaks etc Intended for security law enforcement research and development etc Excellent security device or very interesting science project 8 set Ref F BHT1 BURNING CUTTING CO2 LASER PLANS Projects an invisible beam of heat capable of burning and melting materials over a con siderable distance This laser is one of the most efficient convert ing 10 input power into useful output Not only is this device a workhorse in welding cutting and heat processing materials but it is also a likely candidate as an effective directed energy beam weapon against missiles aircraft ground to ground etc Burning and etching wood cutting plastics textiles etc 12 set Ref F LC7 www bullinet co uk ISSN 0262 3617 PROJ
115. and returned to the main program using a RETURN instruction The main then tested GIE to be clear indicating a valid reading was available Malcolm s Listing 6 highlights the problem of reading a 2 byte value that is continually chang ing Here is a solution that does not require inter rupts to be disabled Read and save the high byte read and save the low byte re read the high byte and check if it is the same as the previous read if not start over again This translates to the fol lowing pic code LOOP MOVF ISRCH W MOVWEF COUNTH MOVE ISRCL W MOVWE COUNTL MOVE ISRCH W XORWF COUNTH W BTFSS STATUS Z GOTO LOOP Malcolm is correct in respect of Microchip having fixed Murphy s last trick Here is an extract from the document 31008a pdf which as far as I know does not appear elsewhere When an instruction that clears the GIE bit is executed any interrupts that were pending for execution in the next cycle are ignored The CPU will execute a NOP in the cycle immedi ately following the instruction which clears the GIE bit The interrupts which were ignored are still pending to be serviced when the GIE bit is set again So if you clear GIE and are also counting instruction cycles for a timing critical section beware the CPU may slip in an extra NOP instruction The moral of this story Read every Microchip document you can find and read it very carefully Finally despite a few minor shortcomings an AVR is a progr
116. and this also indicates cathode In the prototype the flat mark was correctly on the cathode side If you only require a single IR l e d for a shorter detection range then fit a wire link in place of the l e d not required The infra red sensor IC must also be fitted correctly The bump on the surface of the i c indicates the rear non sensing side see Fig 4 Hence it should be fitted with the smooth flat side towards the edge of the p c b Touch an earthed surface such as the case of a metal appliance which is plugged into the mains in order to remove any sta tic electricity in your body before handling IC1 Fit the sensor allowing it to stand proud of the p c b so that it can be folded over the edge later Now fit the relay to the p c b noting that double holes are provided for some of the relay tags since annoyingly relays do not always conform to a standard layout Similarly the transformer should be sol dered into place Neither the specified relay nor transformer will fit the wrong way round If you employ a relay or transformer which is not designed for p c b mounting then you must use insulated wires to make the appropriate connections However IS471F IR WINDOW BUMP ON REAR OF DEVICE o 2 4 V OUT GND IR OV L E D Fig 4 Pinout details for the 1S741F infra red sensor Everyday Practical Electronics July 2002 using the components specified
117. ant RCA and its ruthless Chairman David Sarnoff Boy Genius The equally bitter struggle between David Sarnoff and US TV pioneer Philo Farnsworth has so far been a lot less well documented But a new book by Daniel Stashower just published in the USA The Boy Genius and the Mogul the Untold Story of Television Broadway Books ISBN 0 7679 0759 0 fills the gap And of course the Internet now makes it much easier to buy books inter nationally Stashower s book also provides a use ful reminder that no one really invented television the technology emerged as two competing streams of development mechanical and all electronic con verged Although the mechanical sys tems were all doomed to failure they put pictures on screen much earlier than the electronic systems could do and so whetted the public s appetite for seeing by radio Paul Nipkow began it all with his 1884 idea for a spinning disc to scan an image This was taken up by Charles Francis Jenkins in the USA in 1922 John Logie Baird in the UK in 1926 and Bell Labs in 1927 In 1928 Ernst Alexanderson at RCA switched from disc to mirrored drum It was 1908 when A A Campbell Swinton proposed a cathode ray tube and inspired Edouard Belin who was experi menting in Paris by 1921 Karl Ferdinand Braun Boris Rosing and Vladimir Zworykin took up the idea of displaying pictures on a CRT Philo Farnsworth was a fifteen year old Idaho farm boy when in 1922 he s
118. anteed for 90 days All guarantees on a retum to base basis All rights reserved to change prices specifications without prior notice Orders subject to stock csi aa Years Discounts for volume Top CASH prices paid for surplus goods All trademarks tradenames etc acknowledged Display Electronics 2002 E amp O E NEXT MONTH PIC WORLD CLOCK Inspired by a display originally seen in a hotel lobby this design graphically shows calendar clock and global timezone data Based on a PIC16F877 microcontroller and a graphics l c d the following functions are available Simplified World map Current UK clock and calendar data Clock data for any other timezone adjustable via switches Flashing marker for sun s current highest position i e true noon at that longitude angle in relation to 0 GMT Marker s position vertically latitude varies with the weeks and months throughout the year spanning the Tropics of Capricorn and Cancer Multi paged text display of 150 major cities and their timezone displacements in relation to GMT e g New York 5 hours Sydney 11 hours Additional city timezones can be readily added by readers who have PIC Toolkit Mk2 or Mk3 TKS V1 2 Accuracy of clock time keeping adjustable via switches Principal clock and calendar data stored in the PIC s non volatile EEPROM for recall in the event of power failure Runs from a mains powered 9V battery adaptor plus standby battery ba
119. any more products on our website WWW BITZTECHNOLOGY COM Tel 01753 522 902 Fax 01753 571 657 3 channels RC 11 Key fob Control Transmitter with Rolling Code technology RC 11 Price 14 99 UC 216 3 channels receiver with 2 relays output working from 9V to l2vdc UC 216 with Tear iiio mode and rolling code technology UC 216 9 l2Vdc 29 00 UC 222 240 Vac 29 00 Also Wireless pager alarm PG 4W 125 00 Wireless PIR alarm JA 60S 49 00 Wireless door ma net alarm 39 00 Wireless smoke alarm 49 00 Wireless glass break alarm 49 00 Wireless alarm control panel 99 00 Wireless alarm control panel with digital voice dialler 149 00 Distributors Welcome All prices exclude VAT and carriage All transmitters are licence exempt working on 433 92Mhz All transmitters work with rolling code technology Bitz Technology Ltd sales bitztechnology com Everyday Practical Electronics July 2002 44 0 1753 522 902 521 PRACTICALLY SPEAKING Robert Penfold looks at the Techniques of Actually Doing It T is generally conceived that it is the colour coded components that should give the most identification problems to beginners at electronic project con struction However once you have learnt the basic resistor colour code and one or two variations on it there should be little difficulty in determining the value of any colour coded compo nent Components that are marked with values or type numb
120. applications such as sound pro cessing voice music etc dynamic range is particularly important The perceived by humans dynamic range can be improved by using a non linear conversion characteristic The resolution of an ADC which deter mines the smallest analogue change which it can distinguish with respect to its range is specified by the number of bits or by the percentage of full scale that the LSB repre sents Resolutions as a percentage of full scale for various numbers of bits are also given in Table 9 1 It is instructive to compare these resolu tions with the accuracy available from sen sors and their associated analogue circuits For example there would be little point in using a 16 bit converter with a sensor and measurement circuit which had an inherent and acceptable accuracy of two percent In Fig 9 2 is shown the output of an ideal 3 bit ADC plotted against the input voltage P4 _ oe We 2 32 bit converter B 38 4 8 5 8 GiS TE B8 Analogue input Ws Verr Fig 9 2 Input Output characteristics of a 3 bit DAC The graph also shows the output character istic of a converter with infinite resolution dotted line The difference between the actual characteristic and the infinite resolu tion characteristic is known as the quanti zation error and results in quantization noise in the digital representation of the signal SAMPLING So far we have only considered the volt
121. arked with 12 positions as on a clock face and have selected 1 2 3 4 on the dial as your 4 digit code not recommended with 5 as the Reset digit and 6 as the Duress digit Digits 7 8 9 10 11 and 12 now remain and these are therefore used as Alarm digits The options include the following The 4 digit code 1 2 3 4 opens the lock Reset 5 closes the lock 2 3 the first three digits of the 4 digit code followed by Duress 6 opens the lock and simultaneously sends a secret Duress signal to the Interface p c b The 4 digit code 1 2 3 4 followed by Duress 6 opens the lock then sends a secret Duress signal Duress 6 followed by Reset 5 sends the secret Duress signal just before clos ing the lock Note that Duress only works as a substi tute 4th digit or as an additional 5th digit at the end of the 4 digit code This feature remains disabled until the third digit of the 4 digit code has been selected Positions 7 8 9 10 11 and 12 Alarm all trigger the alarm Selecting 1 2 2 3 would have no effect since four separate digits are required for the 4 digit code each one different from the other Finally 2 1 5 3 as an example would represent a very lucky would be thief Each one of these digits misses both the Alarm and Duress digits The chance of such a 4 digit lucky miss is about 1 in 33 that is 1 5 12 Combination Lock just described to a standard intruder
122. art of the plastic moulding which is to be found at the bot tom of the switch s well Cut or chisel this out then test to see that there is a smooth The rotary switch before modification showing the external limit washer and fix ing nut and washer Part of the switch body showing the internal rotation limit stop pip which has to be removed to allow 360 degrees rotation Everyday Practical Electronics July 2002 360 rotation Now snap the switch shut again carefully so as not to jog the small metal contacts out of place MAIN BOARD Details of the main printed circuit board p c b for the Rotary Combination Lock are shown in Fig 3 This board is available from the EPE PCB Service code 360 Solder the link wires solder pins and the three dual in line d i l sockets Note that some of the link wires are soldered beneath the d 1 1 sockets and that the two link wires beneath MOSFET TR3 should be sheathed to prevent contact with its body when it is mounted flat with the board Next solder in position the resistors diodes and lLe d s continuing with the capacitors and transistors Transistor TR3 is static sensitive and anti static precau tions should be observed the most important being to ground your body immediately before handling via a metal water tap for example In the author s experience f e t TRI is also a fragile device and should be handled with care Be careful to observe the corre
123. atchpanels TH93 49 3COM 16670 12 Port Ethernet hub RJ45 connectors LD97 69 3COM 16671 24 Port Ethernet hub RJ45 connectors 89 3COM 16700 8 Port Ethernet hub RJ45 connectors NEW 39 IBM 53F5501 Token Ring ICS 20 port lobe modules POA IBM MAU Token ring distribution panel 8228 23 5050N 45 AIM 501 Low distortion Oscillator 9Hz to 330Khz IEEE I O 550 ALLGON 8360 11805 1880 MHz hybrid power combiners 250 Trend DSA 274 Data Analyser with G703 2M 64 i o POA Marconi 6310 Programmable 2 to 22 GHz sweep generator 4500 Marconi 2022C 10KHz 1GHz RF signal generator 1550 HP1650B Logic Analyser 3750 HP3781A Pattern generator amp HP3782A Error Detector POA HP6621A Dual Programmable GPIB PSU 0 7 V 160 watts 1800 HP6264 Rack mount variable 0 20V 20A metered PSU 475 HP54121A DC to 22 GHz four channel test set POA HP8130A opt 020 300 MHz pulse generator GPIB etc 7900 HP A1 AO 8 pen HPGL high speed drum plotters from 550 HP DRAFTMASTER 1 8 pen high speed plotter 750 EG G Brookdeal 95035C Precision lock in amp 1800 Keithley 590 CV capacitor voltage analyser POA Racal ICR40 dual 40 channel voice recorder system 3750 Fiskers 45KVA 3 ph On Line UPS New batteries 4500 Emerson AP130 2 5KVA industrial soec UPS 1499 Mann Tally MT645 High speed line printer 2200 Intel SBC 486 133SE Multibus 486 system 8Mb Ram 945 Surrey CR7 8PD Open Mon THE ORIGINAL SURPLUS WONDERLAND THIS MONTH S S
124. ated supply dip a little below 12V but this should not be a problem since a 12V relay should be capable of operating on 9V or less Capacitor C2 is needed to remove any spikes from the supply line No fuse was included though it is assumed that the circuit is driven from a fused supply If this is not the case then a fuse must be added in series with the Live connection on the mains input side termi nal block TB1 Neon indicator with inte gral resistor LP1 is included on the mains input side to provide a warning that the system is live TIME OUT The period for which the output of the monostable I C2b IC2c is positive is set by resistor R2 and capacitor Cl The formula is Time secs R ohms x C farads x 0 7 478 TO MAINS ON NEON LP1 MAINS OUTPUT 3 74 IN 95mm Fig 3 Printed circuit board topside component layout lead off wires and full size underside copper foil master The numbers can be simplified by taking R in megohms and C in microfarads uF Hence using the values in the circuit dia gram Fig 2 Time 0 68 x 1000 x 0 7 476 secs almost 8 minutes Remember that this is the time for which the switch remains on after the last time it was triggered If the pads P1 and P2 on the p c b are joined with a wire link then resistor R3 reduces the time period consid erably Resistor R3 is so much lower than R2 that R2 can be ignored in the calcula tion so the time is
125. attraction of its close association with computer aided design including the FREE software There is a blow by blow guide to the use of EASY PC Professional XM a schematic drawing and printed circuit board design computer package The guide also con ducts the reader through logic circuit simulation using Pulsar software Chapters on p c b physics and p c b production techniques make the book unique and with its host of project ideas make it an ideal companion for the integrative assignment and common skills components required by BTEC and the key skills demanded by GNVQ The principal aim of the book is to provide a straightfor ward approach to the understanding of digital electronics Those who prefer the Teach In approach or would rather experiment with some simple circuits should find the book s final chapters on printed circuit board produc tion and project ideas especially useful eyo ole CA 4 a 17 99 88 pages 5 49 250 pages large format A BEGINNER S GUIDE TO TTL DIGITAL ICs R A Penfold This book first covers the basics of simple logic circuits in general and then progresses to specific TTL logic integrated circuits The devices covered include gates oscillators timers flip flops dividers and decoder cir cuits Some practical circuits are used to illustrate the use of TTL devices in the real world 142 pages Order code BP332 5 45 HOW TO USE OP AMPS E A Parr This boo
126. atts Adjustable sensitivity light level and time delay 9 seconds to 10 minutes 15m detection range mains operated waterproof 5 99 Ref PIR1PACK or a pack of 5 for 22 95 Ref PIR5PACK or 10 for 39 95 Ref PIR10PACK 12V 12Ah SEALED LEAD ACID BATTERIES 100mm x 150mm x 95mm 4kg 15 each Ref SSLB SEALED LEAD ACID CHARGER AND FLOAT CHARGER Complete unit will charge 12V lead acids and maintain them with an automatic trickle charge Charger on its own is 15 Ref LAC or charger and a 12V 12Ah battery all fully cased is 25 Ref ACB AERIAL PHOTOGRAPHY KIT This rocket comes with a built in camera It flies up to 500 feet 150m turns over and takes an aer ial photograph of the ground below The rocket then returns with its film via its parachute Takes 110 film Supplied with everything including a launch pad and 3 motors no film 29 98 Ref Astro BUILD YOUR OWN WINDFARM FROM SCRAP New publication gives step by step guide to building wind generators and propel lors Armed with this publication and a good local scrapyard could make you self sufficient in electricity 12 Ref LOT81 MAGNETIC CREDIT CARD READERS AND ENCODING INFO 9 95 Cased with flyleads designed to read standard credit cards Complete with control electronics p c b and manual cover ing everything you could want to know about what s hidden in that magnetic strip on your card Just 9 95 Ref BAR31 77 KILO LIFT MAGNET These Samarium magnets measure 57mm
127. ay forward is available and it is expected that it will be possible to commercialise this form of data storage using holographic techniques This 484 E LIGHT SENSOR CMOS OR CCD RECORDING STORAGE REFERENCE AND READ BEAM SPATIAL MODULATOR MIRROR WRITE BEAM INCOMING LASER LIGHT BEAM BEAM SPLITTER Fig 1 Basic concept of the new data storage system being developed by Polight Technologies involves optically writing data into a vol ume of photosensitive material This is achieved using a laser The data is encoded into the laser beam using what is known as a spatial light modulator This beam is combined with a reference beam and the combined light is then projected into the material To read the data the reference beam is projected into the material and emerging light contains the data that was written into the material and this can be converted into an electrical format using a CCD or CMOS sensor see Fig 1 The amount of data that can be stored is enormous This is due to the fact that mul tiple images can be stored in the recording material This can be achieved because of the holographic nature of the images and the fact that the material has a very large dynamic range each of the individual images uses up a portion of this range To enable multiple images to be stored the angle of the reference beam is changed Only when the angle of the reference beam used to read the data matches the
128. bona fide the maga zine and its Publishers cannot give any under takings in respect of statements or claims made by advertisers whether these advertise ments are printed as part of the magazine or in inserts The Publishers regret that under no circum stances will the magazine accept liability for non receipt of goods ordered or for late delivery or for faults in manufacture TRANSMITTERS BUGS TELEPHONE EQUIPMENT We advise readers that certain items of radio transmitting and telephone equipment which may be advertised in our pages cannot be legally used in the UK Readers should check the law before buying any transmitting or telephone equipment as a fine confiscation of equipment and or imprisonment can result from illegal use or ownership The laws vary from country to country readers should check local laws 475 Constructional Project INFRA RED AUTOSWITCH MAX HORSEY Simply waving your hand near this versatile IR switch Will cause lights to switch on for a timed period If you stay in the area the unit will remain triggered here will no doubt find many appli cations but it was designed initially to switch on the concealed lighting around a set of kitchen units Simply waving your hand near the unit will cause the lights to switch on for a timed period Also if you stay in the area the unit will remain triggered The sensor employed here is similar to the auto switches used in up market publ
129. ce between A and B is for example 10 metres then its velocity in metres per second is 10 50 x 10 3 xn 5 metres per second obviously it takes two seconds to travel ten metres in this example R Subramaniam age 18 Kodambakkam India Fig 1 Circuit diagram for the Velocity Detector Don t forget to ground the unused inputs of IC3 486 Everyday Practical Electronics July 2002 Car Battery Trickle Charger A Sure Start Wons away out of the country for long periods often resulted in the writer returning home to find his car battery dead Whilst proprietary trickle chargers are avail able they tend to be rather expensive and very bulky The simple trickle charger shown in the circuit diagram of Fig 2 was made from scrap components for just a couple of pounds The prototype has been in use for 18 months and has provided first time starts to a 3 5 litre sports car after standing for a 212 month period and a diesel saloon after six weeks in winter A discarded mains adapter from an old answering machine formed the heart of the unit which produced an unregulated d c output of 17V at 5 00mA An LM317 voltage regulator IC1 was built into the adapter cas ing the device then being connected to the car via the cigar lighter socket The regulator provides a constant voltage under all conditions and therefore a charging current inversely proportional to battery ter minal voltage A state
130. ced users Programs can be written assembled downloaded into the microcontroller and run at full speed up to 20MHz or one step at a time Full emulation means that all I O ports respond exactly and immediately reading and driving external hardware Features include Reset Halt on external pulse Set Breakpoint Examine and Change registers EEPROM and program memory Load program Single Step with display of Status W register Program counter and user selected Watch Window registers KIT 900 34 99 POWER SUPPLY 3 99 STEPPING MOTOR 5 99 Fax 01283 546932 Tel 01283 565435 Everyday Practical Electronics July 2002 EPE PIC TOOLKIT 3 e THE LATEST TOOLKIT BOARD 8 18 28 AND 40 PIN CHIPS e MAGENTA DESIGNED P C B WITH COMPONENT LAYOUT AND EXTRAS e L C D BREADBOARD AND PIC CHIP INCLUDED e ALL TOP QUALITY COMPONENTS AND SOFTWARE SUPPLIED KIT 880 34 99 with 16F84 39 99 with 16F877 PIC TOOLKIT V2 SUPER UPGRADE FROM V1 18 28 AND 40 PIN CHIPS READ WRITE ASSEMBLE amp DISASSEMBLE PICS SIMPLE POWER SUPPLY OPTIONS 5V 20V ALL SWITCHING UNDER SOFTWARE CONTROL MAGENTA DESIGNED PCB HAS TERMINAL PINS AND OSCILLATOR CONNECTIONS FOR ALL CHIPS e INCLUDES SOFTWARE AND PIC CHIP 29 99 with 16F877 KIT 878 22 99 with 16F84 EPE PIC Tutorial At last A Real Practical Hands On Series e Learn Programming from scratch using PIC16F84 e Start by lighting l e d s and do 3
131. ch e Lights Needed Alert Teach In 2002 Power Supply FEATURES e Teach In 2002 Part 1 Practically Speaking Circuit Surgery New Technology Update Ingenuity Unlimited Net Work The Internet Page Free 16 page Supplement PIC Toolkit TK3 For Windows DEC 01 PROJECTS e Ghost Buster PIC Polywhatsit Twinkling Lights Mains Failure Alarm FEATURES e Teach In 2002 Part 2 Marconi The Father of Radio Interface Ingenuity Unlimited Circuit Surgery New Technology Update Net Work The Internet Page 2001 Annual Index JAN 02 PROJECTS e PIC Magick Musick Time Delay Touch Switch Versatile Bench Power Supply Forever Flasher FEATURES e Teach In 2002 Part 3 Practically Speaking Ingenuity Unlimited New Technology Update Circuit Surgery Net Work The Internet U o D PROJECTS PIC Spectrum Analyser Guitar Practice Amp HT Power Supply Versatile Current Monitor FEATURES e Teach In 2002 Part 4 Ingenuity Unlimited Russian Space Shuttle Revisited e Circuit Surgery Interface New Technology Update Net Work The Internet Page MISS THESE BACK ISSUES PROJECTS e MK484 Shortwave Radio PIC Virus Zapper RH Meter PIC Mini Enigma FEATURES e Teach In 2002 Part 5 Ingenuity Unlimited Programming PIC Interrupts 1 Circuit Surgery Practically Speaking New Technology Update Net Work The Internet Page
132. ch is powered at the full volt age of the power supply The latter may be any d c source between about 7V and 15V Everyday Practical Electronics July 2002 9V OV f Ere JETA 0 0 0 0 0 0 a C EA iS cel gee W Eo 0 o o o o rT Ok Wee CWOROROROEORORONOSOICNONORONOHONOMONGI OI ARAR Lela oe SIF To IC1 a Oe Hf ics W CECIAL OIOI AOOO OOOO Bis RM2 RM1 6 0 IN 152 4mm Ne 0000o Sporda ww9 LOL NI Ot CDEFGABCDEFGABCS amp Fig 6 Component layout and full size master track pattern for the EPE StyloPIC printed circuit board Note that capacitor C12 may be mounted on either surface of the board to suit the housing used and is best positioned lying down rather than verti cally Also note that several on board link wires are required below the i c sockets and that resistor modules RM1 and RM2 have orientation marks on their bodies which must correspond in position to the indications in the top figure Everyday Practical Electronics July 2002 491 A 9V battery may be used e g PP3 Capacitor Cl s voltage rating should be increased to 25V for supply voltages above 12V Maximum current consumption will depend on the amplitude output from the power amp In the prototype the current was about 14 5mA with no audio output rising to about 80mA when driving an 8Q speaker at full amplitude with ICS powered at 9V CONSTRUCTION The printed circuit board component layout and trackin
133. circuit Additionally we are told that the item Emergency Light Unit by Steve Cartwright shown in the November 2001 issue is the same as a circuit devised by Alan Ainslie in Practical Wireless January 1976 and for this we apologise to PW Publishing Everyday Practical Electronics publishes readers own circuits in good faith with a view to encouraging more efforts in circuit design providing an outlet for ideas and 6 lithium battery 3V 20mm diameter x 1 6mm high 1 00 56 068 CR2025 lithium battery 3V 20mm diameter x 2 5mm high 1 00 42 544 Lithium button cell CH2032 aV 20mm diameter x 3 2mm thick Brand new not surplus 1 00 socket 3 95 80 102 IDE hard disk drive cable with CIGAR LIGHTER PLUG Fig 2 Circuit diagram for the Car Battery Trickle Charger A novel application of a standard circuit observing all the usual precautions when dealing with lead acid batteries David John Gibbs Southport inspiring readers to develop ideas for them selves EPE does everything possible to authenticate the circuits and contributors are required to sign a written legal dis claimer and confirmation of originality Copyright infringement is a serious matter and readers who copy material and claim it is their own could be prosecuted Those who would attempt to defraud the column would do well to remember that EPE has many tens of thousands of very loyal readers around the world some of them with extre
134. ck up A REVOLUTION BIG EARS IN EVOLUTION BUGGY We hear about advances in electronics all the time smaller circuits A simple fun buggy that will move towards faster chips new devices and technologies But there s another revolution a sound speak to it and it will turn and happening one that in a few years may change electronics forever and move towards you Uses inexpensive perhaps even lead to the development of the first truly intelligent circuitry bolted to a simple chassis The machines This new revolution is called Evolutionary Electronics circuit could find a number of other One of the most interesting and unusual attributes of this revolution is its applications where the direction of sound accessibility to hobbyists The answers to the big questions aren t clear needs to be monitored yet and the rewards for getting it right are immense The experiments don t need million dollar machines or laboratories just access to some good computing equipment and a degree of ingenuity We all know what evolution is it is a simple and elegant concept If you take a population of animals which have random genes and leave them in a particular environment those with good traits will survive and those that are not as fit will die The better suited members of the population survive to breed and to mix and pass on their good traits to the next generation So why not do the same with circuits Set them up randomly test how good they ar
135. cle of modern technology SAS By GE our special buying power A quality product fea turing a fully cased COLOUR CCD camera at a give away price Unit features full autolight sensing use in low light amp high light applications A 10 mm fixed focus wide angle lens gives excellent focus and resolution from close up to long Se range The composite video output will AS Pu ia Se to any composite monitor or TV i via SCART socket and most video an recorders Unit runs from 12V DC so ideal for security amp portable applica ser are tions where mains power not available Overall dimensions 66 mm wide x 117 deep x 43 high Supplied BRAND NEW amp fully guaranteed with user data 100 s of applica tions including Security Home Video Web TV Web Cams etc etc Order as LK33 ONLY 79 00 or 2 for 149 00 B NT4 WorkStation complete with service pack 3 and licence OEM packaged ONLY 89 00 e ENCARTA 95 CDROM Not the latest but at this price 7 95 DOS 5 0 on 3 disks with concise books c w QBasic 14 95 Windows for Workgroups 3 11 Dos 6 22 on 3 5 disks 55 00 Windows 95 CDROM Only No Licence 19 95 Wordperfect 6 for DOS supplied on 3 disks with manual 24 95 shipping charges for software is code B Visible red 670nm laser diode assembly Unit runs from 5 V DC at approx 50 mA Orginally made for continuous use in industrial bar code scanners the laser is mounted in a removable solid aluminium block which functions as
136. ct 2000 is now available on CD ROM Plus the Teach In 2000 interac tive software covering all aspects of the series and Alan Winstanley s Basic Soldering Guide including illustrations and Desoldering Teach In 2000 covers all the basic principles of elec tronics from Ohm s Law to Displays including Op Amps Logic Gates etc Each part has its own section on the inter active software where you can also change component values in the various on screen demonstration circuits The series gives a hands on approach to electronics with numerous breadboard circuits to try out plus a sim ple computer interface which allows a PC to be used as a basic oscilloscope ONLY 12 45 including VAT and p amp p Robotics INTRODUCING ROBOTICS WITH LEGO MINDSTORMS Robert Penfold Shows the reader how to build a variety of increasingly sophis ticated computer controlled robots using the brilliant Lego Mindstorms Robotic Invention System RIS Initially covers fundamental building techniques and mechanics needed to construct strong and efficient robots using the various click together components supplied in the basic RIS kit Then explains in simple terms how the brain of the robot may be programmed on screen using a PC and zapped to the robot over an infra red link Also shows how a more sophisticated Windows programming language such as Visual BASIC may be used to control the robots Details building and programming instruct
137. ct orien tation of the electrolytic capacitors tran sistors diodes and i c s Attach the solenoid and I e d D2 to the allocated solder pins Finally solder rotary wafer switch S1 into place on the p c b Thoroughly check the accuracy of your assembly and soldering and then insert the CMOS i c s C1 and IC2 again observing anti static precautions No case is specified since the Rotary Combination Lock could be used in any number of applications and thus mounted in various places Ensure that the p c b and switch are well protected from the elements The solenoid may be used as is so that its plunger normally resides in a corre sponding hole in a door frame Alternatively a mechanical arrangement may be used as shown in Fig 4 A suitable cover may then be used to enclose the mechanics Firmly fix a dial with a pointer to the shaft of rotary switch S1 if the pointer slips out of place your combination could be lost SETTING UP Having ensured that there are no solder bridges or short circuits on the board con nect it to a 12V 1A power supply Check first that power MOSFET TR3 remains cool If it does not turn off the power immediately and re check the circuit X1 SOLENOID C1 nay F gt R2 ANODE a 6 ALARM DURESS eE Ro oe fe se eat D2 a 2 l O Ht E ORG CATHODE D2 A 24 PIN DIL OCKET Fig 3 Rotary Combination Lock printed c
138. cts Great introduction to electronics Ideal for the budding electron Lab ics expert Build a radio burglar alarm water detector morse code practice circuit simple computer circuits and much more NO soldering tools or previous electronics knowledge required Circuits can be built and unassembled repeatedly Comprehensive 68 page manual with explanations schematics and assembly diagrams Suitable for age 10 Excellent for schools Requires 2 x AA batteries Order Code EPL030 ONLY 14 95 phone for bulk discounts 130 300 and 500 in ONE also available Everyday Practical Electronics July 2002 Secure Online Ordering Facilities Full Kit Listing Descriptions amp Photos Kit Documentation amp Software Downloads eSVICS PACD HPVJdID SGZZ9VvV GLE LO GENT ELECTRONI C S Tel 01283 565435 Fax 546932 http www magenta2000 co uk E mail sales magenta2000 co uk LT D EE239 135 Hunter Street Burton on Trent Staffs DE14 2ST All Prices include V A T ADD 3 00 PER ORDER P amp P 6 99 next day MAIL ORDER ONLY CALLERS BY APPOINTMENT EPE MICROCONTROLLER P I TREASURE HUNTER The latest MAGENTA DESIGN highly stable amp sensitive with I C control of all timing functions and advanced pulse separation techniques High stability drift cancelling e Easy to build amp use No ground effect works in seawater e Detects gold silver fe
139. d frequency Which leaves me thinking many people in the Rife and Beck camps apparently swear that their system is the right one Therefore one must con clude that the choice of frequency is isn t impor tant And when I put my pennyworth in we also understand that the supply should be a c d c Yes they are silly statements but how can they be refuted I am not lying and I am sure that the Rife and Beck supporters are not lying either Are we mistaken then as to what really heals us Could be I look forward to other readers opinions May I also comment that the EPE PIC Virus Zapper catries no health warning and point out that Dr Hulda Clark in her book states Do not zap if you are pregnant or wearing a pacemaker Stan Hood Christchurch New Zealand via email Andy Flind replies I recently had two really bad colds in quick succession My original zapper has been loaned to a chap in Scotland so I knocked up a genera tor for a zapper output only this one can do both 2 5kHz and 20kHz I applied it through adhesive electrodes on my wrists and manually timed the sessions not having a PIC programmed for this The sore throat cleared up overnight and on the day after the first treatment I felt a bit thick headed no really as they say you sometimes will when you first use a zapper on a problem Like Stan I can t say whether I d have got better anyhow or the zapper did the job but something fixed my pr
140. d in circuits that do not have to be particular ly stable but they are not suitable for high precision applications because of the high sensitivity of these voltages to changes in temperature The Zener diode is more sta ble than the Vgg voltage by about a factor of three but Zener diodes are noisy and the stability is simply not good enough for many critical applications Note that the arrow in a circle symbol in Fig 1 is a constant current source which we have discussed before in Circuit Surgery In this case we could simply use a resistor on the assumption that the supply voltage and Vgg Voltages do not change much The Vgg voltage of the circuit in Fig 1 would typically be about 0 6V at room tem perature but it has a negative temperature coefficient in fact Vgg decreases by about 2mV per degree Celsius increase Some temperature sensor circuits actually make use of this very characteristic We can use the diode connected transis tor as long as we compensate for the tem perature change One way of doing this is to add Vp to another voltage which has the opposite temperature coefficient If we take two transistors of different physical sizes supplied with the same current as shown in Fig 2 it turns out that the tem perature coefficient of the difference between the two Vp voltages labelled AVgg or delta Vgr is positive So if we build a circuit with an output V given by Vief VBE k AV pr
141. d check their understanding Version 2 has been considerably expanded in almost every area following a review of major syllabuses GCSE GNVQ A level and HNC It also contains both European and American circuit symbols Sections include Fundamentals units amp multiples electricity electric circuits alternating circuits Passive Components resistors capacitors inductors transformers Semiconductors diodes transistors op amps logic gates Passive Circuits Active Circuits The Parts Gallery will help students to recognise common electronic components and their corresponding symbols in circuit diagrams Included in the Institutional Versions are multiple choice questions exam style questions fault finding virtual laboratories and investigations worksheets Circuit simulation screen ANALOGUE ELECTRONICS Analogue Electronics is a complete learning resource for this most difficult branch of electronics The CD ROM includes a host of virtual laboratories animations diagrams photographs and text as well as a SPICE electronic circuit simulator with over 50 pre designed circuits Sections on the CD ROM include Fundamentals Analogue Signals 5 sections Transistors 4 sections Waveshaping Circuits 6 sections Op Amps 17 sections covering everything from Symbols and Signal Connections to Differentiators Amplifiers Single Stage Amplifiers 8 sections Multi stage Amplifiers 3 sections Filters Passive Fil
142. d versions of the full Labcenter software ISIS Lite which provides full schematic drawing features including full control of drawing appearance automatic wire routing and over 6 000 parts PROSPICE Lite integrated into ISIS Lite which uses unique animation to show the operation of any circuit with mouse operated switches pots etc The animation is compiled using a full mixed mode SPICE simulator ARES Lite PCB layout software allows professional quality PCBs to be designed and includes advanced features such as 16 layer boards SMT components and an autorouter operating on user generated Net Lists ROBOTICS amp MECHATRONICS i pm a Case study of the Milford Instruments Spider Robotics and Mechatronics is designed to enable hobbyists students with little previous experience of electronics to design and build electromechanical systems The CD ROM deals with all aspects of robotics from the control systems used the transducers available motors actuators and the circuits to drive them Full case study material including the NASA Mars Rover the Milford Spider and the Furby is used to show how practical robotic systems are designed The result is a highly stimulating resource that will make learning and building robotics and mechatronic systems easier The Institutional versions have additional worksheets and multiple choice questions Interactive Virtual Laboratories Little previous knowledge required
143. de ee ee eee elelee eeel ee eee ed ed een fet en feed eed eed eee fet et et ee eed ede ee fet en eee eed eee et eee eee eee eee eee Wimborne Publishing Ltd Dept Y7 408 Wimborne Road East Ferndown Dorset BH22 9ND Tel 01202 873872 Fax 01202 874562 Online shop www epemag wimborne co uk shopdoor htm E a aa IT Sa I IS P L EAS E send me ORDER FORM Simply complete and return the order form with your payment to the following address Wimborne Publishing Ltd Dept Y7 408 Wimborne _ THE MODERN ELECTRONICS MANUAL CD ROM version only Please allow four working days for UK delivery Card No ee ee ee Card Exp Date eee eee eee NOTE Surface mail can take over 10 weeks to some parts of I I I I l ELECTRONICS SERVICE MANUAL plus a FREE SUPPLEMENT Printed version only Road East Ferndown Dorset BH22 9ND I I enclose payment of 29 95 for one Manual or 49 90 for both Manuals saving 10 by We offer a 30 day MONEY BACK GUARANTEE I ordering both together plus postage if applicable on ESM see the panel above for details l i also require the appropriate ESM Supplements four times a year These are billed i i separately and can be discontinued at any time Please delete if not required POSTAGE CH ARG ES FOR ESM i MEM CD ROM POST FREE TO ALL COUNTRIES i FUE NAME eiaa ere teres o E E A aE ores wy EE G ee wa ee ar Geer nee Ge a aE a ere oe Ger Note we use the VAT portion of the MEM CD ROM payment l PLEA
144. dvice on hardware and software and a list of industry contacts 116 pages Order code PC117 11 95 HIGH POWER AUDIO AMPLIFIER CONSTRUCTION R A Penfold Practical construction details of how to build a number of audio power amplifiers ranging from about 50 to 300 400 watts r m s includes MOSFET and bipolar transistor designs Order code BP277 4 49 96 pages 537 Circuits Data and Design PRACTICAL ELECTRONIC FILTERS Owen Bishop This book deals with the subject in a non mathematical way It reviews the main types of filter explaining in sim ple terms how each type works and how it is used The book also presents a dozen filter based projects with applications in and around the home or in the constructors workshop These include a number of audio projects such as a rythm sequencer and a multi voiced electronic organ Concluding the book is a practical step by step guide to designing simple filters for a wide range of purposes with circuit diagrams and worked examples Order code BP299 DIGITAL ELECTRONICS A PRACTICAL APPROACH FREE With FREE Software Number One Systems EASY PC Professional XM and Pulsar Limited Functionality Richard Monk Covers binary arithmetic Boolean algebra and logic gates combination logic sequential logic including the design and construction of asynchronous and synchro nous circuits and register circuits Together with a consid erable practical content plus the additional
145. e their fitness and allow the best ones to survive and mix their traits to breed Well this can be done and it has been done with some very interesting results as you will see next month NO ONE DOES IT BETTER gt ACTICAL DON T MISS AN A CHROINGS Shorn sonn CEA pemand 1s pound to be Mah Everyday Practical Electronics July 2002 467 wWwWWWw QuasarElectronics comnm Established 1990 uasaR ELECTRONICS LIMITED PO Box 6935 BISHOPS STORTFORD Herts CM23 4WP TEL 01279 467799 ADD 2 00 P amp P to all orders or 1st Class Recorded 4 Next day Insured 250 7 Europe 5 00 Rest of World 10 00 We accept all FAX 07092 203496 S major credit cards Make cheques PO s payable to Quasar Electronics Prices include 17 5 VAT MAIL ORDER ONLY FREE CATALOGUE with order or send 2 x 1st class stamps refundable for details of over 150 kits amp publications gna PROJECT KITS Our electronic kits are supplied complete with all components high quality PCBs NOT cheap Tripad strip board and detailed assembly operating instructions 2 x 25W CAR BOOSTER AMPLIFIER Connects to the output of an existing car stereo cassette player CD player or radio Heatsinks provided PCB 76x75mm 1046KT 24 95 3 CHANNEL WIRELESS LIGHT MODULATOR No electrical connection with amplifier Light modu lation achieved via a sensitive electret microphone Separate
146. e book with hun dreds of photos depicting the develop ment of the British wireless set up to the late 1960s The three volumes of our own Wireless For the Warrior by Louis Meulstee are also available These are a technical his tory of radio communication equipment in the British Army from pre war through to the 1960s For details see the shop on our UK web site at www epemag wimborne co uk or contact us for a list of Radio Bygones books BOOK ORDERING DETAILS All prices include UK postage For postage to Europe air and the rest of the world surface please add 1 per book For the rest of the world airmail add 2 per book CD ROM prices include VAT and or postage to anywhere in the world Send a PO cheque international money order sterling only made payable to Direct Book Service or card details Visa Mastercard Amex Diners Club or Switch minimum card order is 5 to DIRECT BOOK SERVICE WIMBORNE PUBLISHING LTD 408 WIMBORNE ROAD EAST FERNDOWN DORSET BH22 9ND Books are normally sent within seven days of receipt of order but please allow 28 days for delivery more for overseas orders Please check price and availability see latest issue of Everyday Practical Electronics before ordering from old lists For a further selection of books see the next two issues of EPE Tel 01202 873872 Fax 01202 874562 Email dbs epemag wimborne co uk Order from our online shop at www epemag wimborne co uk shopdoor htm
147. e control of complex devices like 7 segment displays motor controllers and c d displays The use of macros allows you to control these electronic devices without getting bogged down in understanding the programming involved Flowcode produces MPASM code which is compatible with virtually all PlCmicro programmers When used in conjunction with the Version 2 development board this provides a seamless solution that allows you to program chips in minutes Requires no programming experience Allows complex PlCmicro applications to be designed quickly Uses international standard flow chart symbols ISO5807 Full on screen simulation allows debugging and speeds up the development process Facilitates learning via a full suite of demonstration tutorials Produces ASM code for a range of 8 18 28 and 40 pin devices Institutional versions include virtual systems burglar alarms car parks etc Burglar Alarm Simulation PRICES Prices for each of the CD ROMs above are Order form on next page Hobbyist Student Institutional Schools HE FE Industry Flowcode Institutional Institutional 10 user Network Licence Site Licence 45 inc VAT 99 plus VAT 70 plus VAT 249 plus VAT 599 plus VAT UK and EU customers add VAT at 17 5 to plus VAT prices TEACH IN 2000 LEARN ELECTRONICS WITH EPE EPE s own Teach In CD ROM contains the full 12 part Teach In series by John Becker in PDF form pl
148. e excessive dis Sipation in the output transistors and if there is no overload protection circuitry the power amplifier will be ruined 503 Safe supply voltage and speaker imped ance combinations for the various i c power amplifiers were given in Part 1 They are summarised here in Table 2 CROSSOVERS When two or more speakers are used to improve performance arrangements must be made to allocate the audio spectrum between them The resistance presented by capacitors to the flow of alternating current decreases as frequency rises With inductors resis tance increases with rising frequency This frequency dependant opposition to current flow is known as reactance Capacitors and inductors can be com bined in simple networks which utilise this phenomenon to allocate frequency bands to different speakers Circuits and design data are given in Fig 3 and inductor and capacitor values for common speaker impedances and a range of crossover frequencies are set out in Table 3 The reactances of standard value capacitors at RPI e FIRST ORDER NETWORK TWO SPEAKER SYSTEM Make reactance of inductor L and capacitor C at the crossover fre quency equal to the rated speaker impedance pur c SECOND ORDER NETWORK TWO SPEAKER SYSTEM 1 Calculate inductor and capacitor values as for the first order network 2 Divide the capacitor values by 1 4 and multiply the inductor values by 1 4 to obtain the correct
149. e of O or 31 binary 00111111 depending on the state of the count If bit 5 of COUNTER is high then 31 is output otherwise the output value is 0 In both instances the four NOP commands at PLAY2 are bypassed The NOPs are again there for timing bal ance this time between the different times it takes to process the ramp waveform compared to the squarewave If you study the full listing for the StyloPIC you will find numerous NOP commands inserted all to maintain the tim ing balance between various stage aspects IT IS IMPERATIVE that you do NOT change the number of NOPs You will lose tuning consistency if you do 494 LISTING 2 PLAYIT movf FREQLO W addwf WAVELO F movt STATUS W andlw 1 addwf WAVEHI F movf STATUS W andlw 1 addwf OUTPUT F movf FREQHI W addwf WAV EHI F movf STATUS W andlw 1 addwf OUTPUT F movf OUTPUT W btfsc MASK 0 goto PLAY2 yes movlw 0 btfsc OUTPUT 5 movlw 00111111 goto OUTIT get freq LSB and add it to WAVE LSB add Carry if any to WAVE MSB add Carry if any to OUTPUT register get freq MSB and add it to WAVE MSB add Carry if any to OUTPUT register is MASK 1 ramp no so square needed should output be low no it should be high nop timing balance delay nop nop nop movwt PORTA goto MAIN SOFTWARE The StyloPIC software was written in TASM grammar on Toolkit TK3 through which it can be translated to MPASM grammar for use with such software
150. e of V ef and show that the range can be changed A full datasheet for the ADC0804 can be found at the National Semiconductor web site Www natsemi com Lab 9 3 Illustration of Aliasing Time Domain We can illustrate aliasing very easily using the Picoscope and the sinewave 534 Fig 9 13 Picoscope display of a sinewave at 1kHz generator from Part 8 Fig 8 11 Connect the generator to the Picoscope input and set the frequency to about IkHz The Picoscope display should be similar to that in Fig 9 13 showing that the signal is almost correctly dis played Now increase the signal to 4kHz again the almost correct waveform should be displayed but with a small amount of aliasing just begin ning to appear Fig 9 14 Increase the input frequency further until it is about 10kHz you IC2 ADC0804 Fig 9 14 Picoscope display at 4kHz beginning to show a small amount of aliasing should see something like that in Fig 9 15 It does not look much like a pure 10kHz sinewave It is the sampling rate fixed inside the Picoscope software that causes this Fig 9 15 Picoscope display at 10kHz dramatically showing how aliasing has disrupted the signal quality Everyday Practical Electronics July 2002 Lab 9 4 Illustration of Aliasing Frequency Domain Aliasing can also be seen by using the Picoscope Spectrum Analyser See Panel 9 1 for details of how to operate the analyser Select the Spectrum Analyz
151. e original simple yet very effective idea Everyday Practical Electronics July 2001 READOUT E mail editorial epemag wimborne co uk John Becker addresses some of the general points readers have raised Have you anything interesting to say Drop us a line WIN A DIGITAL MULTIMETER A 31 2 digit pocket sized I c d multime ter which measures a c and d c volt age d c current and resistance It can also test diodes and bipolar transistors Every month we will give a Digital Multimeter to the author of the best Readout letter x LETTER OF THE MONTH amp P C B SIZES AGAIN Dear EPE Regarding the enquiry by Dave Stacey on p c b sizes Readout June 02 I have also had re sizing problems with pdf file p c b sizes and with trying to import pdf files into Photo Suite Photo Studio and Photo Plus for editing The ubiquitous free Adobe Acrobat Reader unfortunately allows no graphics editing Not only that but scan ning poor quality paper magazine layouts produces unwanted image artifacts and can cause closely placed tracks and pads to merge on the final printout making the scan unusable as a p c b master image I have found a solution it is so simple quick and easy and produces such accurate and high quality p c b masters from both pdf files and scanned images that at first I could not believe that it worked It is also free Obtain a copy of Paint Shop Pro PSP I use version 4 15 but a
152. e runner up Velocity Detector Specal of ligint AY optically triggered counter timer which can be used to measure the time taken for a moving object to break two light beams in suc cession is shown in the circuit diagram of Fig 1 It is suggested that a pair of budget price laser pointers could be used as precision light sources with the beams shining onto a pair of small light dependent resistors R2 and R4 The moving body interrupts the beams in succes sion and a period is displayed by a timer circuit When the object crosses A it sets the bistable formed from IC2a and IC2b which triggers a 555 timer via IC3 The output waveform is sent to a dual decade counter The number of pulses produced is count ed passed to a digital decoder driver and displayed on a seven segment l e d display The counter stops when the body moves past point B In Fig 1 the multivibrator IC4 is wired as a gated astable to produce pulses of 50ms duration per pulse The decade counters IC5 and IC7 IC1b are wired to produce BCD binary coded decimal outputs which are 7404 decoded by the BCD decoder drivers IC6 and IC8 Common anode 7 segment displays are used to display tens and units Clearly the accuracy of the design is determined by that of the 555 astable which may need trimming or adjusting with the aid of an oscilloscope If the number of 50ms pulses clocked by a moving body is n say 40 for example and the distan
153. egardless of the manufacturer concerned so it is impor tant to obtain a component that has precisely the right type number It is oth erwise virtually certain that you will obtain completely the wrong device or the right chip but in the wrong encapsulation Transistors and Diodes Transistors and diodes do not have the same type number variations as integrated circuits The prefix does not usually indicate the manufacturer although there are some exceptions such as the TI and TIL prefix used by Texas Instruments Devices having European codes start with two letters that indicate the semiconductor material used and the type of component as detailed below First Letter Meaning A Germanium B Silicon C Gallium Arsenide R Compound materials Second Letter Meaning Small signal diode Rectifier or variable Capacitance diode Small signal audio transistor Power transistor Point contact diode Low power high fre quency transistor Hall effect device High frequency power transistor Opto isolator Photo diode LED Thyristor or triac High voltage transistor Rectifier High power rectifier Zener diode N lt XK CHAOVZ CFA MMV O WS A BC109 for example is therefore a small silicon transistor for audio use The number is simply a serial type starting from 100 American semiconductors have a 1N 2N or ON prefix The number is one less than the number of leads the device has so diodes and rectif
154. egular Supplements Unlike a book or encyclopedia this Manual is a living work continuously extended with new material If requested Supplements are sent to you on approval approximately every three months Each Supplement contains around 160 pages all for only 23 50 2 50 p amp p You can of course return any Supplement within ten days which you feel is superfluous to your needs You can also purchase a range of past Supplements to extend your Base Manual on subjects of particular interest to you Presentation Durable looseleaf system in large A4 format Price of the Basic Work 29 95 to include a recent Supplement FREE equipment Reference data Easy to use format Clear and simple layout Vital safety precautions Professionally written Regular Supplements Sturdy gold blocked ring binder Our 30 day money back guarantee gives you complete peace of mind If you are not entirely happy with the Electronics Service Manual for whatever reason simply return it to us in good condition within 30 days and we will make a full refund of your payment no small print and no questions asked All we ask is that you pay the return postage Overseas buyers also have to pay our overseas postage charge Sorry but we can only make exchanges on the Modern Electronics Manual CD ROM version if the CD ROM is faulty we cannot offer a money back guarantee on this product as the content can be printed out i ed ed ee en et ee e
155. elpfile Now the hard bit on the TK3 circuit board you must cut the track between printer connector pin 6 DA4 and TP4 Then unsolder the ends of resis tors R7 and R3 connected to TP3 and lift them off the board Now connect TP3 to TP4 I also took out the wire link connecting TP6 to IC2c pin 2 but maybe not needed try leaving it in first Now run the ICPROG programmer you down loaded and under hardware select PROPIC2 ICPROG will treat TK3 like PROPIC2 and can program PICs TK3 software cannot It s easy to reverse these circuit changes Stanley Cartwright via email That s useful Stanley thanks I have not yet found a situation where I wanted to use a 12C device Should I ever do so I ll probably upgrade TK3 to cope with it 495 VIRUS ZAPPING Dear EPE I have used a virus zapper of the type designed by Andy Flind and published in your March 02 issue but do not know whether or not it helped a virus infection I had for several weeks in an ear canal last year I like to keep an open mind on these matters Antibiotics had not been able to heal this infection However I recently had an identical infection in the same ear canal and it hurt just the same too much to ignore So it happened with this new infection that a highly experimental brain wave stimulator I designed and built about 15 years ago forcibly came out of retirement to act as a source of capacitor discharge spikes for a six inch diameter coil I
156. en the unit is next switched on Tuning adjustment is in relation to the value held in the MSB most significant byte of the 2 byte tuning value in the author s default block For example if tun ing upwards is needed the author s MSB is retrieved from the Eeprom halved and added to the LSB least significant byte of the value for the equivalent note in the user s block automatically incrementing the user s note MSB if a Carry roll over of the LSB results from the addition The process is automatically repeated by the software routine for all 25 notes Similarly if a decrease in pitch is required half the value of the author s MSB is subtracted from the user s LSB MSB Restoration of the author s defaults simply entails copying these val ues into the user s data Eeprom block Each adjustment is only performed once for any call via the Reset option As soon as the adjustment has been made the PIC waits until the stylus has been removed from the selected key It then stores the new values back to the user s Eeprom block Having done so and even if adjustment has not been called the software extracts all values from the user s Eeprom GET NOTES routine called in Listing 1 and stores them into a 50 byte wide block 25 pairs of note values of the normal data registers NOTEVAL commencing at 30 These are the tuning values then accessed by the software when the StyloPIC is in normal use When the val
157. ents must be built into a circuit like kit 3082 above 30A15 14 95 PIC 16C71 FOUR SERVO MOTOR DRIVER Simultaneously control up to 4 servo motors Software amp all components except servos control pots supplied 5VDC PCB 50x70mm 3102KT 15 95 UNIPOLAR STEPPER MOTOR DRIVER for any 5 6 8 lead motor Fast slow amp single step rates Direction control amp on off switch Wave 2 phase amp half wave step modes 4 LED indicators PCB 50x65mm 3109KT 14 95 PC CONTROLLED STEPPER MOTOR DRIVER Control two unipolar stepper motors 3A max each via PC printer port Wave 2 phase amp half wave step modes Software accepts 4 digital inputs from exter nal switches amp will single step motors PCB fits in D shell case provided 3113KT 17 95 12 BIT PC DATA ACQUISITION CONTROL UNIT Similar to kit 3093 above but uses a 12 bit Analogue to Digital Converter ADC with internal analogue multiplexor Reads 8 single ended channels or 4 dif ferential inputs or a mixture of both Analogue inputs read 0 4V Four TTL CMOS compatible digital input outputs ADC conversion time lt 10uS Software C QB amp Win extended D shell case amp all compo nents except sensors amp cable provided 3118KT 52 95 LIQUID LEVEL SENSOR RAIN ALARM Will indi cate fluid levels or simply the presence of fluid Relay output to control a pump to add remove water when it reaches a certain level 1080KT 5 95 AM RADIO KIT 1 Tuned Radio Freque
158. equip ment and make it safe Pack of 10 just 9 98 Ref LOT5B INFRA RED REMOTE CONTROL WATCHES 16 99 VIBRATING WATCHES vibrate when your phone rings 16 99 PULSE WATCHES display your pulse 16 99 www quemex co uk STEPPER MOTORS Brand new stepper motors 4mm fixing holes with 47 14mm fixing centres 20mm shaft 6 35mm diameter 5V phase 0 7A phase 1 8 deg step 200 step Body 56mm x 36mm 14 99 each Ref STEP6 pack of 4 for 49 95 BASIC GUIDE TO LOCKPICKING New publication gives you an insight 6 Ref LPK NEW HIGH POWER MINI BUG With a range of up to 800 metres and 3 days use from a PP3 this is our top selling bug Less than 1in square and a 10m voice pick up range 28 Ref LOT102 IR LAMP KIT Suitable for CCTV cameras enables the camera to be used in total darkness 6 Ref EF 138 INFRA RED POWERBEAM Handheld battery powered lamp 4in reflector gives out powerful pure infra red light Perfect for CCTV use nightsights etc 29 Ref PB1 YOUR HOME COULD BE SELF SUFFICIENT IN ELECTRICITY Comprehensive plans with loads of info on designing systems panels control electronics etc 7 Ref PV1 200 WATT INVERTERS plugs straight into your car cigarette lighter socket and is fitted with a 13A socket so you can run your mains operated devices from your car battery 49 95 Ref SS66 THE TRUTH MACHINE Tells if someone is lying by micro tremors in their voice battery operated works in general conversation and
159. er set the sampling rate to 1OkHz and FFT size to 1024 Input a 1kHz sinewave and observe the display you should see a peak in the spectrum at about 1kHz Increase the frequency to 4kHz the peak in the display should correspond Fig 9 16 Now increase it to 5kHz and then 6kHz The peak will go from the far right hand side of the display 5kHz and move to the left reading 4kHz as shown in Fig 9 17 Fig 9 16 Spectrum analysing a 4kHz sinewave at 10kHz Fig 9 17 When spectrum analysing a 6kHz sinewave at 10kHz aliasing causes the waveform to be shown as representing a 4kHz signal Carry on increasing the frequency and see what happens When the frequency is 10kHz the peak should read OHz Fig 9 18 Further increasing the input fre quency continues to increase the displayed spectrum which goes up again Fig 9 18 When spectrum analysing a 10kHz sinewave at 10kHz the display indicates that the signal is occurring at around OHz Everyday Practical Electronics July 2002 PANEL 9 1 Picoscope Spectrum Analyzer The Picoscope Spectrum Analyzer can be started from within the oscilloscope display either by clicking the button on the panel second button from the left or via the View drop down menu select new spectrum The spectrum is shown with frequency on the x axis and signal power in dB on the y axis The default set up is for a maximum frequency of 10kHz and an FFT Fast Fourier Transform size o
160. er supply which should be between 4 5V and 16V Pin 4 acts as a sink to provide the coded signal for the IR l e d s and pin 2 is the output When a reflected signal is detected the output at pin 2 switches from positive to OV This is used to trigger a monostable timer The monostable switches on a transistor and relay which in turn switches on the lights or any other device CIRCUIT DETAILS The full circuit diagram for the Infra Red Autoswitch is shown in Fig 2 The IS471F infra red sensor IC1 is connected to a pair of infra red l e d s D1 and D2 as shown Note that no series resistor is required since the current is regulated by the i c In tests two l e d s provided a longer detection range than one but three made no difference If a shorter range is required a single l e d could be employed it is also possible to reduce the range by adding a resistor in series with the l e d s Everyday Practical Electronics July 2002 The monostable is based around the well tried and tested CMOS 4001B chip which houses four NOR gates Gates IC2b and IC2c are configured as a monostable and a positive signal is required at pin 5 of gate IC2b to trigger the time period As stated IC1 provides an output which switches to OV when an object is detected So it is necessary to invert this signal and this is achieved by means of gate IC2a whose inputs pin 1 and pin 2 are con nected together thus making it behave as a NOT gate or in
161. era up to 100m range audio and video UK legal complete with infra red lights 169 Ref WMS333 PELTIER MODULES 56W 40mm x 40mm 16V sealed edges new and boxed Supplied with 18 page Peltier design manual fea turing circuit designs design information etc 1 module and manu al is 29 99 Ref PELT1 pack of 4 modules and manual is 99 99 Ref PELT2 The manual on its own is 4 Ref PELTS DC MOTOR 12V d c general purpose model motor 70mm x 50mm 12V d c permanent magnet 4mm x 25mm shaft 6 Ref GPM1 pack of 10 is just 40 Ref GPM2 180R P M MAINS MOTOR Induction type 90mm x 70mm 50mm x 5mm shaft 12A continuous rating thermal protected 22 Ref MGM1 SOLID STATE RELAYS P C B mounting these relays require 3 32V d c to operate but will switch up to 3A a c mains Pack of 4 5 Ref SPEC1B 12V RELAYS 2 x 2 c o 16A contacts p c b mount will fit Vero tray of 25 relays for just 9 95 Ref SPEC1 VENNER TIME CONTROLS Designed to be wired in permanent ly they will switch up to 16A 240V a c motorised with dial and pins New and boxed 15 Ref VTS GYROSCOPES We siill sell original 1917 design hours of fun for all the family complete with stand string box and info 6 Ref EP70 INNOVATIONS We also sell a wide range of innovative products for the home these are at www seemans com INVERTERS Convert 12V d c into 240V mains modified sine wave 300 watt 150 watt continuous 59 95 Ref VER3
162. ers using letters and numbers should leave even less room for error and each one should be exactly what it says on the casing Clear as Mud It is clear from readers letters that things are not as straightforward as this in practice Readers having problems with a project often include descriptions of some of the components that they suspect of being the wrong thing Semiconductors in general and inte grated circuits in particular are proba bly the worst offenders when it comes to spurious markings Even experienced project builders can sometimes take a while to sort out the wheat from the chaff Matters are cer tainly easier if you understand the fundamentals of semicon ductor type numbers Understandably most semi conductor manufacturers like their name or logo to be promi nently displayed on their prod ucts Virtually all integrated cir cuits carry a manufacturer s name such as MAXIM or more usually a logo see Fig 1 One or other of these is often squeezed onto small semiconductors such as low power transistors These are usually easy to spot and should not give any major problems In addition to the name or logo of the manufacturer and the type number most semicon ductors usually have some additional letters and numbers Over the years there has been a ten dency for the logos and additional markings to become more prominent at the expense of type numbers etc This can be very confusin
163. erve the same purpose only the switches are now wired between the Duress input and OV while a pull up resistor of 22k is taken from this input to the positive power line see Fig 7b Bear in mind that the Alarm input has the Inhibit function while the Duress input reacts immediately to every positive pulse it receives The Inhibit function may be removed simply by taking out diode D1 from the p c b Normally open switches may also be used These are wired in parallel and in 518 NORMALLY CLOSED ALARM DURESS NORMALLY CLOSED OV Fig 7 Circuit details for a stand alone alarm system this case the positions of the 22kQ resistors and the switches are swapped around OTHER USES The single action switch was described earlier A dead man s handle can perform a vitally important function in certain situations In a recent highly publicised case near the author a pump attendant left his pump apparently for lunch and a team in some water filled caves below nearly lost their lives A dead man s handle could prevent such incidents by sounding an alarm if for instance a pump is abandoned for too long or if as the term suggests the pump attendant should drop dead This is accomplished as follows the alarm sounder is connected to relay RLA s POLE and N O connections The Interface s Alarm input is then tied low with a 22kQ pull down resistor which is wired betwee
164. ery Net Work The Internet Page JULY 01 PROJECTS e Stereo Surround Sound Amplifier e PIC to Printer Interface Perpetual Projects 1 Solar Powered Power Supply and Voltage Regulator MSF Signal Repeater and Indicator FEATURES e The World of PLCs e Ingenuity Unlimited Circuit Surgery New Technology Update Net Work The Internet Page PROJECTS e Digitimer Lead Acid Battery Charger Compact Shortwave Loop Aerial Perpetual Projects 2 L E D Flasher Double Door Buzzer FEATURES e Controlling Power Generation Ingenuity Unlimited Interface Circuit Surgery e New Technology Update Net Work The Internet Page SEPT 01 PROJECTS e Water Monitor L E D Super Torches Synchronous Clock Driver Perpetual Projects 3 Loop Burglar Alarm Touch Switch Door Light Solar Powered Rain Alarm FEATURES e Controlling Flight Ingenuity Unlimited Practically Speaking Circuit Surgery New Technology Update Net Work The Internet Page OCT 01 Photostats onl PROJECTS e PIC Toolkit Mk3 Camcorder Power Supply 2 Valve SW Receiver Perpetual Projects 4 Gate Sentinel Bird Scarer In Out Register FEATURES e Traffic Control Ingenuity Unlimited New Technology Update e Circuit Surgery e Interface Net Work The Internet Page Free 2 CD ROMs Microchip 2001 Tech Library 498 DID YO NOV 01 PROJECTS e Capacitance Meter Pitch Swit
165. ese questions and more are answered in this concise and practical book which explains everything you need to know about MP3s in a simple and easy to understand manner It explains How to play MP3s on your computer How to use MP3s with handheld MP3 players Where to find MP3s on the Web How MP3s work How to tune into Internet radio stations How to create your own MP3s How to record your own CDs from MP3 files Other digital audio music formats Whether you want to stay bang up to date with the lat est music or create your own MP3s and join the on line digital music revolution this book will show you how 60 pages Order code PC119 7 45 60 pages ALL PRICES INCLUDE UK POST AND PACKING CD ROM prices include VAT and or postage to anywhere in the world Everyday Practical Electronics July 2002 ELECTRONIC MUSIC AND MIDI PROJECTS R A Penfold Whether you wish to save money boldly go where no musi cian has gone before rekindle the pioneering spirit or sim ply have fun building some electronic music gadgets the designs featured in this book should suit your needs The projects are all easy to build and some are so simple that even complete beginners at electronic project construction can tackle them with ease Stripboard layouts are provided for every project together with a wiring diagram The mechanical side of construction has largely been left to individual constructors to sort out simply because the vast majo
166. et The latest sensitive transducer and double balanced mixer give a stable high perfor mance superheterodyne design KIT 861 24 99 ALSO AVAILABLE Built amp Tested 39 99 ULTRASONIC PEsT SCARER Keep pets pests away from newly sown areas fruit vegetable and flower beds children s play areas patios etc This project produces intense pulses of ultrasound which deter visiting animals e KIT INCLUDES ALL COMPONENTS PCB amp CASE e EFFICIENT 100V TRANSDUCER OUTPUT RANGE PIC16F877 now in stock e COMPLETELY INAUDIBLE TO HUMANS some projects are copyright KIT 812 P s tar E A Le pr rowk Src e UP TO 4 METRES e LOW CURRENT DRAIN Everyday Practical Electronics July 2002 SIMPLE PIC PROGRAMMER INCREDIBLE LOW PRICE Kit 857 12 99 INCLUDES 1 PIC16F84 CHIP Power Supply 3 99 SOFTWARE DISK LEAD CONNECTOR PROFESSIONAL EXTRA CHIPS PIC 16F84 4 84 PC BOARD amp INSTRUCTIONS Based on February 96 EPE Magenta designed PCB and kit PCB with Reset switch Program switch 5V regulator and test L E D s and connection points for access to all A and B port pins PIC 16C84 DISPLAY DRIVER Kit 860 19 99 Power Supply 3 99 FULL PROGRAM SOURCE CODE SUPPLIED DEVELOP YOUR OWN APPLICATION Another super PIC project from Magenta Supplied with PCB industry standard 2 LINE x 16 character display data all components and software to inc
167. eturns to its non excited state accompanied by the release of a gamma ray Gamma rays are electromagnetic in nature We can write nuclear decay as an equa tion For example the decay of uranium 238 into thorium 234 is written as ST INCIDENT RADIATION DO XS BT as 238 234 4 99 U gt oo LN 5He The top number is the atomic mass and the bottom the atomic number This decay produces an alpha particle which as just said is a helium nucleus As another exam ple the conversion of carbon 14 to nitro gen 14 produces a negatron and a neutrino v and is written as l i CN Apy ENVIRONMENTAL NUCLEAR RADIATION Nuclear radiation always makes the news because of an inherent fear of radia tion induced diseases such as leukaemia and cancers Radiation is always present in very small quantities and it is calculated that 87 percent of the radiation to which we are exposed each year comes from natural sources such as rocks soil space cosmic rays and food source This Common Inheritance Britain s Environmental Strategy Government White Paper 1990 Most of the remainder is from medical uses Our exposure to radiation also depends on where we live granite bearing rocks produce radon Rd an inert but radioactive gas In fact it is estimated that 50 percent of radiation in the UK is from radon If you are interested in radon browse METAL WIRE OUTPUT TO AMPLIFIER CATHODE GAS FILLED CHAMBER
168. exes 3 30 for five inc p amp p Overseas 3 80 surface 5 25 airmail L_ I enclose cheque P O bank draft to the value of L_ Please charge my Visa Mastercard Amex Diners Club Switch CANO creere carat 2h oe ote ahs we E wes Card Expiry Date SEND TO Everyday Practical Electronics Wimborne Publishing Ltd 408 Wimborne Road East Ferndown Dorset BH22 9ND Tel 01202 873872 Fax 01202 874562 E mail orders epemag wimborne co uk On line Shop www epemag wimborne co uk shopdoor htm Payments must be in sterling cheque or bank draft drawn on a UK bank Normally supplied within seven days of receipt of order Send a copy of this form or order by letter if you do not wish to cut your issue Everyday Practical Electronics July 2002 STORE YOUR BACK ISSUES ON MINI CD ROMS 1 2 45 each Including VAT A great way to buy EPE Back Issues our mini CD ROMs contain back issues from our EPE Online website plus bonus articles all the relevant PIC software and web links Note no free gifts are included All this for just 12 45 each including postage and packing VOL 1 CONTENTS NOTE These mini CD ROMs are suitable for use on any PC witha BACK ISSUES November 1998 to June 1999 all the projects CD ROM drive They require Adobe features news Us etc from all eight issues Note No advertise ments are included PIC PROJECT CODES All the available reine jarrah areal nenom codes for the
169. f 256 points The number of points in the FFT deter mines the frequency resolution of the dis play the higher the number of points always a power of 2 the better the reso lution but the slower the update of the display because it takes longer to calcu late the spectrum The Spectrum Analyzer operates on blocks of data and calculates the FFT for each block One problem with this is that the division of the signal into blocks introduces distortion in the form of side lobes in the spectrum because the end of a block is abrupt giving rise to addition al false frequency components This is overcome by multiplying the data by a window which reduces the data at the beginning and end of the block pro gressively to zero to remove the abrupt ends There are many windows available which can be selected via the settings This behaviour can be explained by Nyquist the sampling frequency is 10kHz and the maximum input frequency is there fore 5kHz For an input frequency f below f 2 the output is f between f 2 and fg the output is fof Lab 9 5 Anti aliasing Filter Build the circuit of Fig 9 19 which is nearly identical to Fig 8 16 in last month s Lab Work The filter has a cut off frequen cy of 4kHz determined by the oscillator formed around ICla which has an output at approximately 400kHz Placing this filter between the input signal and the Picoscope should stop all options menu F5 The default set up is Blac
170. ffix that denotes the case style Having several manufacturers pro ducing the same chip might seem a lit tle odd but equipment producers do not like being tied to a single source for components Having a second source of supply or even several sources makes a component more marketable Unfortunately it also results in the same component being marketed under several slightly different type numbers Provided you obtain the cor rect chip it should not matter which particular manufacturer it was pro duced by unless stated otherwise Not all integrated circuits are avail able with multiple prefixes Some devices are only produced by one manufacturer and this is particularly common with the more specialised types Others are produced under the same type number regardless of which company actually made the device The NE suffix for the eight pin chip in Fig 1 suggests it was made by Signetics but the logo clear ly indicates that it was made by Philips Logic The devices that are most likely to have a variety of prefixes are the popu lar operational amplifiers and logic devices both of which are commonly used in projects for the home construc tor In components lists it is normal for only the basic type number to be spec ified or perhaps the basic type number plus a suffix With the 4000 series CMOS logic devices for example a type number such as 4066BE might be specified Here 4066 is the basic type
171. g Just call the target phone amp activate the unit to hear all room sounds Great for home office security R019 3 50 THE ETHER BOX CALL INTERCEPTOR PLANS Grabs telephone calls out of thin air No need to wire in a phone bug Simply place this device near the phone lines to hear the conversations taking place R025 3 00 CASH CREATOR BUSINESS REPORTS Need ideas for making some cash Well this could be just what you need You get 40 reports approx 800 pages on floppy disk that give you information on setting up different businesses You also get valuable reproduction and duplication rights so that you can sell the manuals as you like R030 7 50 468 PC CONTROLLED RELAY BOARD Convert any 286 upward PC into a dedicated auto matic controller to independently turn on off up to eight lights motors amp other devices around the home office laboratory or factory Each relay output is capable of switching 250VAC 4A A suite of DOS and Windows control programs are provided to gether with all components except box and PC cable 12VDC PCB 70x200mm 3074KT 31 95 2 CHANNEL UHF RELAY SWITCH Contains the same transmitter receiver pair as 30A15 below plus the components and PCB to control two 240VAC 10A relays also supplied Ultra bright LEDs used to indicate relay status 3082KT 27 95 TRANSMITTER RECEIVER PAIR 2 button keyfob style 300 375MHz Tx with 30m range Receiver encoder module with matched decoder IC Compon
172. g details are shown in Fig 5 This board is available from the EPE PCB Service code 359 Assemble in any convenient order you prefer using sockets for the d i l dual in line i c s and observe the correct orientation for the polarity sensitive components including resistor modules RM1 and RM2 Note that capacitor C12 is physically large It may be mounted flat on either side of the board to suit the type of housing in which the StyloPIC is housed It seems likely that in most instances mounting on the trackside would be more suitable as done with the test model Treat all i c s as static sensitive and dis charge static electricity from your body before handling them touch a water pipe or the bare metal of a grounded item of workshop equipment Do not insert them until the correctness of the regulated 5V power supply has been proved If you intend programming your PIC in situ see later do not connect Reset switch S2 until you have done so it uses one of the programming terminals STYLOPIC CASING The test model was not mounted in a case and is simply enjoyed as an unprotect ed fun instrument on the author s work bench No definitive suggestions for hous ing your own are offered but you may find inspiration from the earlier photograph of an original Stylophone A plastic slim line case measuring about 180mm x 120mm x 40mm might also be considered In this instance the p c b could perhaps be mounted so that it s
173. g for beginners but the secret of success is to look for meaningful markings and ignore every thing else The extraneous markings are usually just things like batch numbers the date of manufacture in some obscure form a code number indicating the particular factory where the component was made and things of this general type They are of course of no relevance to the project builder The secret of success with compo nent markings is to avoid panicking if you are faced with a jumble of digits 322 and look for something that could be a type number or value Things like batch numbers are usually in a form that avoids them being easily confused with type numbers or values It helps to bear in mind that the con vention with integrated circuits is for the type number to be given first followed by any batch number etc Hence the eight pin device shown in Fig 1 is an NE602AN and not an FSH4930 or 9501nA Similarly the 16 pin device is a MAX232CPE and not a 9450N Unfortunately the same convention is not used with capacitors and most other components Numbers Up Even if you manage to ignore the spurious markings there can still be problems with the type number or value Integrated circuits are undoubt edly the worst offenders since the same chip can be sold under different type numbers In general the basic type number is the same but it is pre ceded by the manufacturer s code let ters and followed by a su
174. g multi choice questions with feedback GCSE Aimed at the Electronics in many Design amp Technology courses it covers many sections of GCSE Electronics Provides an ideal revision guide with Homework Questions on each chapter Worked answers with an access code are provided on a special website Single User 29 inc VAT Multiple User 39 plus VAT Student copies available only with a multiple user copy 6 plus VAT UK and EU customers add VAT at 17 5 to plus VAT prices MODULAR CIRCUIT DESIGN Contains a range of tried and tested analogue and digital circuit modules together with the knowledge to use and interface them Thus allowing anyone with a basic understanding of circuit symbols to design and build their own projects Version 3 includes data and circuit modules for a range of popular PICs includes PICAXE circuits the system which enables a PIC to be programmed without a programmer and without removing it from the circuit Shows where to obtain free software downloads to enable BASIC programming Essential information for anyone undertaking GCSE or A level electronics or technology and for hobbyists who want to get to grips with project design Over seventy different Input Processor and Output modules are illustrated and fully described together with detailed information on construction fault finding and components including circuit symbols pinouts power supplies decoupling etc Single User 19 95 inc
175. g of lock Relay supplied 3029KT 10 95 ULTRASONIC MOVEMENT DETECTOR Crystal locked detector frequency for stability amp reliability PCB 75x40mm_ houses all components 4 7m range Adjustable sensitivity Output will drive external relay circuits 9VDC 3049KT 13 95 PIR DETECTOR MODULE 3 lead assembled unit just 25x85mm as used in commercial burglar alarm systems 3076KT 8 95 INFRARED SECURITY BEAM When the invisible IR beam is broken a relay is tripped that can be used to sound a bell or alarm 25 metre range Mains rated relays provided 12VDC operation 3130KT 12 95 SQUARE WAVE OSCILLATOR Generates square waves at 6 preset frequencies in factors of 10 from 1Hz 100KHz Visual output indicator 5 18VDC Box provided 3111KT 8 95 PC DRIVEN POCKET SAMPLER DATA LOG GER Analogue voltage sampler records voltages up to 2V or 20V over periods from milli seconds to months Can also be used as a simple digital scope to examine audio amp other signals up to about 5KHz Software amp D shell case provided 3112KT 18 95 20 MHz FUNCTION GENERATOR Square tri angular and sine waveform up to 20MHz over 3 ranges using coarse and fine frequency adjust ment controls Adjustable output from 0 2V p p A TTL output is also provided for connection to a frequency meter Uses MAX038 IC Plastic case with printed front rear panels amp all components provided 7 12VAC 3101KT 69 95 30 in ONE Electronic Proje
176. g subjects BASIC PRINCIPLES Electronic Components and their Characteristics 16 sections from Resistors and Potentiometers to Crystals Crystal Modules and Resonators Circuits Using Passive Components 10 sections Power Supplies The Amateur Electronics Workshop The Uses of Semiconductors Digital Electronics 6 sections Operational Amplifiers Introduction to Physics including practical experiments Semiconductors 5 sections and Digital Instruments 3 sections CIRCUITS TO BUILD There s nothing to beat the satisfaction of creating your own projects From basic principles like soldering and making printed circuit boards to the tools needed for circuit building the Modern Electronics Manual and its Supplements describe clearly with appropriate diagrams how to assemble a radio loudspeaker circuits amplifiers car projects a computer interface measuring instruments workshop equipment security systems medical and musical circuits etc The Base Manual describes 12 projects including a Theremin and a Simple TENS Unit ESSENTIAL DATA Extensive tables on diodes transistors thyristors and triacs digital and linear i c s EXTENSIVE GLOSSARY Should you come across a technical word phrase or abbreviation you re not familiar with simply look up the glossary included in the Manual and you ll find a comprehensive definition in plain English The Manual also covers Safety and provides web links to component and equipmen
177. g water supply with mc WATER variable frequency electromagnetic DESCALER signals May reduce scale formation dissolve existing scale and improve lathering ability by altering the way salts in the water behave Kit includes case P C B coupling coil and all components High coil current ensures maximum effect L E D monitor KIT 868 22 95 POWER UNIT 3 99 MICRO PEsT SCARER Our latest design The ultimate scarer for the garden Uses special microchip to give random delay and pulse time Easy to build reliable circuit Keeps pets pests away from newly sown areas play areas etc uses power source from 9 to 24 volts e RANDOM PULSES e HIGH POWER e DUAL OPTION ie ore eT eee ee eee ee KIT SLAVE UNIT 000005 32 50 WINDICATOR A novel wind speed indicator with LED readout Kit comes complete with sensor cups and weatherproof sensing head Mains power unit 5 99 extra DUAL OUTPUT TENS UNIT As featured in March 97 issue Magenta have prepared a FULL KIT for this excellent new project All components PCB hardware and electrodes are included Designed for simple assembly and testing and providing high level dual output drive KIT 866 Full kit including four electrodes 32 90 1000V amp 500V INSULATION TESTER Superb new design Regulated output efficient circuit Dual scale meter compact case Reads up to 200 Megohms 4 spare electrodes
178. gly trivial comment can help Use capitalisa tion or punctuation to make it clear how many lines comments apply to In the list ings shown in this article comments start with a capital letter and continue over more than one line where appropriate to the line before another headed by a capital letter For example in Listing 1 the first comment applies to the first two lines Check your spelling g Remember comments are written once but read many times Test your com ment writing quality by reviewing what you wrote six months ago to determine if it still makes sense h Where appropriate put things in alphabetical order RESOURCE The full illustrative software listing for this article is available from the EPE Editorial office on 3 5in disk EPE Disk 5 for which a nominal handling charge applies see PCB Service page and is also available for free download from our ftp site accessible via the top of the main page at WwWww epemag wimborne co uk and held in folder PUB PICS PCLATH Note that only the software for Toolkit TK3 V1 2 and higher version numbers can handle addresses above 2K and the PCLATH command COMING SOON We have a number of short PIC pro gramming features in the pipeline These are just two to look out for Using PICs and Square Roots Algorithm Peter Hemsley again shows us a programming routine that is extremely well thought out is neat and compact and works beautifully it is a super
179. good idea to use one in place of the other Fig 2 The device on the left is a 2SD666A and the one on the right is a 2SA872A A more common variation is where a suffix letter is added to a European transistor type number This letter indi cates that the device is in a particular gain group as follows Letter Gain Range A 110 to 220 B 220 to 450 C 420 to 800 If no suffix is given in a components list it does not matter which gain group you use and it is also all right to use a device that lacks the suffix Where a particular gain group is specified it will usually be the highest C suffix group It is quite likely that the project will not work properly if you use a tran sistor from the wrong gain group or one that is not graded A few American devices and the 2N2926 in particular use coloured spots on the device to indicate its gain group This method is based on the resistor colour code with brown representing the lowest gain group and red orange yel low etc representing progressively high er gain ranges Again if a particular colour is specified it is important to use a device from the correct gain group Colour coding is little used with semi conductors but there are some American diodes that use a variation on the resistor colour code to indicate the serial number For example a 1N914 diode would have white brown and yellow bands to respectively indi cate the 9 1 and 4 part of the type nu
180. gs and these are connected in parallel to double the current available Select the trans former with care so that its pins fit the p c b When the a c supply from transformer Tl secondaries is full wave rectified by REC1 and smoothed by capacitor C3 the resulting d c voltage is increased by a fac tor of about 1 4 times though this is sub ject to a voltage drop caused by the bridge diodes The current available is reduced by the same percentage So a transformer rated at 9V 28mA per secondary winding was employed the two coils being connected in parallel to achieve 9V 56mA After rectification and smooth ing the voltage available is around 12V and the current around 40mA REGULATION The original prototype design used this unregulated supply to drive the circuit and all was well However the actual voltage produced by the transformer depends upon the current flowing and when the circuit is in standby mode the current is very small and so the voltage rises well above its nom inal value Small transformers of the type employed here are particularly bad in this respect The i c s in the circuit can tolerate up to 16V but there was a danger that the voltage may rise beyond this when in standby mode So a 12V voltage regulator IC3 was added This limits the supply to 12V regardless of whether the circuit is in standby mode or activated The current required by the relay coil when activated will make the regul
181. half the ADC conversation rate A low pass filter preferably with a nice sharp cut off and minimal pass band distortion is typi cally required see last month for informa tion on filters Although we are concentrating on ADCs it is worth noting that the analogue signal obtained directly from a DAC would look something like Fig 9 3b In order to obtain a smooth continuous time analogue signal the DAC output is filtered using a low pass filter with a cutoff at half the sample fre quency This would restore b to the form shown in a NYQUIST FORMULA The Nyquist sampling criterion is writ ten mathematically as Js ZMAX where fmax iS the maximum frequency in the signal As we mentioned earlier this is an extremely important concept and needs more explanation Fig 9 4 shows three iden tical sinewaves sampled at exactly 2fyax 1 5fmax and fmax The sampling points are denoted by the vertical lines and the dots If we try to reconstruct the signal by putting the sampled signals through a low 530 Fig 9 3 Example of the effect of sampling frequency a Right Fig 9 4 lllustration of aliasing pass filter then we can see that in a the signal can be reconstructed successfully but in b we get a lower frequency In the worst case when fs fmax We get a d c signal We can look at this another way by examining what happens in the frequency domain Fig 9 5a shows an amplitude ver sus frequency graph for a s
182. he investment I also recommend Paint Shop Pro in Easy Steps by Stephen Copestake 8 99 The publisher in UK is Computer Step tel 01926 817999 Roger Lucas via email That appears to be very useful info Roger Whilst I have not tried it it seems that the technique should also work with the standard Paint program supplied in the Accessories folder of all Windows based PCS FED WIZPIC Dear EPE I have been learning PIC assembler over the last few months with a regard to several pro jects I have been wanting to design build for years Last month I came across Forest Electronic Developments www fored co uk who sell a PIC development simulation sys tem for Windows called WIZ ASM This product is fantastic value for money and it has allowed me to move on in leaps and bounds I now write code and test it with appropriate simulated hardware before I get near a pro grammer or a single real component Fantastic I rate this product 10 10 for value and usefulness Well done FED Geoff Sim via email Yes Geoff we know that FED do good prod ucts and that they are a very helpful company PIC627 8 DEVICES Dear EPE I assume you re aware that the price of the PIC16F84 and 16F84A has recently increased quite dramatically Checking Farnell s web site I found that the 16F627 and 628 were by comparison a bar gain If the price differential is likely to persist which I suspect will be the ca
183. he situation dictates Only four wires need to be taken from the Interface p c b to the main p c b namely OV VE Alarm and Duress Make sure that there are no shorts where these wires are connected As soon as these wires are connected the Interface is ready to receive Alarm and Duress pulses from the lock Fig 5 Complete circuit diagram for the Interface and stand alone alarm system Note the TR2 inhibit function The two sets of relay contacts can be used for a variety of switching applications inhibited for about half an hour which should allow ample time to reset the lock This period would increase to about two hours with a value of 4u7 and would be reduced to about two and a half minutes with a value of 100n This inhibitory feature may be used to good effect with a front doorbell so that the doorbell is only permitted to sound once during a specific time period this is the single action switch mentioned earli er If you have callers who maddeningly press the doorbell every so many seconds the Interface will permit only one bell press to get through every so many seconds or minutes UNDER DURESS The same feature is not provided for the Duress input since Duress pulses can only reach the Interface board should at least three correct digits of the lock be selected beforehand It therefore seems highly unlikely that anyone should accidentally send a Duress pulse to the Interface board
184. hniques as applied to digital logic Order code PC106 9 95 96 pages 200 pages Music Audio and Video QUICK GUIDE TO ANALOGUE SYNTHESIS lan Waugh Even though music production has moved into the digi tal domain modern synthesisers invariably use ana logue synthesis techniques The reason is simple analogue synthesis is flexible and versatile and it s rel atively easy for us to understand The basics are the same for all analogue synths and you ll quickly be able to adapt the principles to any instrument to edit exist ing sounds and create exciting new ones This book describes How analogue synthesis works The essen tial modules every synthesiser has The three steps to synthesis How to create phat bass sounds How to generate filter sweeps Advanced synth modules How to create simple and complex synth patches Where to find soft synths on the Web If you want to take your synthesiser of the hardware or software variety past the presets and program your own sounds and effects this practical and well illustrated book tells you what you need to know Order code PC118 7 45 QUICK GUIDE TO MP3 AND DIGITAL MUSIC lan Waugh MP3 files the latest digital music format have taken the music industry by storm What are they Where do you get them How do you use them Why have they thrown record companies into a panic Will they make music easier to buy And cheaper Is this the future of music All th
185. hould click on Assuming that you have not connected a mains supply you can verify that the relay is working by connecting a multimeter set to resistance to the terminals marked L on TBI and L on TB2 When the relay contacts close the meter should give a reading of about zero or bleep When power is first applied to the board the relay should switch on Assuming that pads P1 and P2 are joined together the relay should remain on for about 7 sec onds If the relay remains on for longer it may be because the IR receiver C1 is being triggered by the IR le d s Try shielding the sensor with thick paper card or Blu Tack If all is well disconnect the multimeter and temporary low voltage supply Do not connect the mains supply until the p c b is safely housed and secured into its case FAULT FINDING Fault finding should only be carried out if the circuit 1s powered from a separate 9V or 12V battery supply as described ear lier i e do not connect the circuit to a mains supply A voltmeter is the only test instrument required connect the negative lead of the voltmeter to the OV track the very bottom on the p c b Begin at the sensor IC1 end of the cir cuit and take readings with the positive lead of the voltmeter starting with the power pins of ICI pin 1 positive and 3 OV Now test pin 2 output of IC1 This should be positive when a signal is not received switching to OV when the IR beam is ref
186. ible variances in the quality and condition of materials and workmanship used by readers EPE Online its publishers and agents disclaim any responsibility for the safe and proper functioning of reader constructed projects based on or from information published in these materials and works In no event shall Maxfield amp Montrose Interactive Inc or Wimborne Publishing Ltd be responsible or liable for any loss of profit or any other commercial damages including but not limited to special incidental consequential or any other damages in connection with or arising out of furnishing performance or use of these materials and works GAS MASKS RUSSIAN new and boxed NATO filter 39 LOW COST NIGHT VISION system Russian handheld complete with infra red illuminator 0Om range Runs on 2 AA batteries just 109 95 COBRA NIGHT VISION equipment also stocked more info on our web site at www cobra optics co uk ELECTRIC SCOOTERS 18kph 24V motor 6 hour charge time 22kg weight max load 90kg running time up to 1 hour range 15km 8 5A motor 24V direct drive Our Price 229 95 Ref ESCOOT VOICE CHANGERS Hold one of these units over your phone mouthpiece and you can adjust your voice using the controls on the unit Battery operated 15 Ref CC3 EMMINENCE LOUDSPEAKERS 12in dia 50W nom 100W peak 16 ohm impedance Pack of 4 just 39 95 Ref SPEAK39 PIR SECURITY SWITCHES These brand new swivel mounting PIR units will switch up to 2 kilow
187. ic wash handbasins and handdriers where the water or air is switched on when your hand is in place It is important not to make the unit too sensitive otherwise false triggering will occur The system is triggered when your hand is about 30cm from the unit The pro totype was concealed underneath a kitchen cupboard the distance between the unit and the worksurface being too large to cause false triggering The project was designed for maximum ease of assembly and fitting with all com ponents including the transformer being housed on a printed circuit board p c b The only connections required are the mains supply input and lighting output Ti Infra Red Autoswitch described IS471F OUT IR WINDOW GND 0V POWER MONOSTABLE SUPPLY DARLINGTON DRIVER Fig 1 Block schematic diagram for the Infra Red Autoswitch INTELLIGENT SENSOR The infra red system is based on the inexpensive but intelligent S471F infra red sensor i c This i c provides a signal which may be used to directly drive one or two infra red l e d s A coded signal is applied to the IR l e d s and having transmitted the beam the i c waits for the signal to be reflected The reflected signal is detected by a win dow built into the i c and when the signal is received the output switches from posi tive to zero volts A basic block schematic diagram is shown in Fig 1 The IS471F is a 4 pin device pin 1 and pin 3 connect to the pow
188. ical aspects of servicing Repair techniques are also illustrated throughout A large reference section provides a range of infor mation compiled from many contemporary sources and includes specialist dealers for valves components and complete receivers Order code NE34 288 pages 20 50 Computers and Computing MULTIMEDIA ON THE PC lan R Sinclair In this book you ll find out what a CD ROM is how it works and why it is such a perfect add on for a PC allowing you to buy programmes text graphics and sound on a CD It also describes the installation of a CD ROM drive and a sound card pointing out the common problems that arise and then shows how to use them to create a complete multimedia presentation that con tains text photos a soundtrack with your own voice recorded as a commentary even animation and edited video footage Order code PC112 HOW TO BUILD YOUR OWN PC Morris Rosenthal More and more people are building the own PCs They get more value for their money they create exactly the machine they want and the work is highly satisfying and actually fun That is if they have a unique begin ners guide like this one which visually demonstrates how to construct a state of the art computer from start to finish Through 150 crisp photographs and clear but minimal text readers will confidently absorb the concepts of computer building The extra big format makes it easy to see what s going on in the pictures
189. iers have 1N type numbers and transis tors mostly have 2N type numbers A few transistors have four leads and a 3N type number Again the number following the suffix is a serial type Devices having Japanese Industry Standard JIS type numbers are occa sionally used in EPE projects These start with a number that indicates the number of leads in the same way as the American system The next digit is always an S and the third digit indi cates the type of component using a code letter D for a low frequency npn transistor for example This is followed by the usual serial number One slightly confusing aspect of Japanese type numbers is that the first two digits are often absent from the actual components A 2SC646 for example would probably just be marked C646 Fig 2 shows two more examples Since the first two digits are of little practical value there absence is of no real importance Transistor Suffixes Clearly small semiconductors have rigidly standardised type numbers and there is not the free for all associated with integrated circuits The only varia tions are in the suffixes applied to some transistors With the American devices there is sometimes an A on the end of the type number and this is used to indicate that the device concerned is an improved version of the basic device The original and improved versions are effectively two different devices and it is not a
190. ignal with ener gy present up to fmax Note that we have negative frequencies to fmax don t worry about this it is a consequence of the mathematics When we sample this signal we get a graph like that in Fig 9 5b which is a repeated to infinity series of spectra centred at fg 2f5 3fy 4f etc Now if fy is greater than 2fmax the spectra are separated but if fg is smaller the spectra overlap Fig 9 5c This is aliasing and it means that the origi nal signal cannot be reconstructed If the signal is a single frequency sine wave then as its fre quency is increased up to f 2 it will be correctly sampled Between f 2 and fg the signal will appear to have a frequency of fsf until f fo when o s the output will be d c If the frequency is increased further then it will appear to start again at d c and increase We will be looking at this in the Lab experiments In practice the sam pling frequency is usually quite a bit larger than 2fmax to c ALIASING b ORIGINAL SIGNAL b SAMPLED SIGNAL SAMPLE RECONSTRUCTED SIGNAL RECONSTRUCTED SIGNAL guarantee a good representation of the sig nal Obviously the higher the sampling rate the better the representation see Fig 9 3 but this has an immediate conse quence more samples per second equates to more memory storage So there is a compromise between qual ity and memory storage Audio CDs are a good example of this The
191. im of this series has been to look in depth at sensors and the cir cuitry connected directly to them However apart from their use in very basic measurement instruments sensors are usual ly part of larger systems where their signals are interpreted or processed in some form of computer or other complex digital circuit For EPE readers the PIC microcon troller is likely to form the heart of many sensor based systems but in general a large range of microcontrollers PCs DSPs digital signal processors and custom designed integrated circuits are used to process sensor data We will not be covering PIC program ming or PIC interfacing in this series but this month we look at the fundamental issues involved in converting sensor data from analogue to digital A to D form As usual we will be looking at some sensors and this month it is the turn of nuclear radi ation sensing Since it is difficult to design labs for nuclear radiation sensing we will be looking at analogue to digital conver sion problems and solutions WHY GO DIGITAL Up to now nearly all of our circuits have been analogue in nature so why change to digital There are several reasons why dig ital signals are better than analogue Digital signals are better for transmitting down long cables since an analogue sig nal is degraded due to the wire s resis tance and the addition of noise So at the end of the wire the analogue signal s SNR signal t
192. individual versions of the StyloPIC due to the crystal generated fre quency not being at exactly 20MHz This is a perfectly natural situation with crystals As with other component types crystal values have a manufacturing tolerance spread Not only that if the StyloPIC is to be used alongside other instruments it may be desirable to change its pitch to suit the pitch set for the other instruments Consequently a pitch adjustment option has been provided within the software Pitch tuning can be shifted symmetrical ly across all 25 notes both upwards and downwards The author s default values can also be recalled to replace the user s own values should the need arise Tuning of individual notes is not allowed for nor is it desirable since the frequency relation ship between each note is mathematically derived ideal note frequencies are shown in Table 1 Consequently any frequency shift has to be applied equally relative to each note s mathematical ideal Table 1 Mathematically calculated ideal frequency values for the notes covered by the StyloPIC Note Frequency Hz C 261 625 C 277 182 D 293 664 D 311 126 E 329 627 FP 349 229 P 369 994 G 391 995 G 415 304 A 440 000 A 466 163 B 493 883 C 523 251 C 554 364 D 587 328 D 622 252 E 659 254 F 698 458 F 739 988 G 783 990 G 830 608 A 880 000 A 932 326 B 987 766 o 1046 50 Thus
193. ing periods of Cla and IC1b which may be set between about 0 7 seconds and two and a half minutes with the component values shown The timing periods are cal culated with the following formulae t 0 69 x VR1 R4 x C2 t 0 69 x VR2 R7 x C5 Where is the timing period in seconds Resistance is in ohms Capacitance is in farads If you have an existing intruder alarm system this would normally make provi sion for normally closed loop inputs The POLE and N C outputs of the two relays S17 N O RLA POLE N C N O RLB POLE SEE TEXT wiwgg NIEZ 2 4IN 60mm Fig 6 Interface topside component layout lead off wiring details and full size underside copper foil master pattern on the Interface p c b are taken to these inputs of the intruder alarm system or the POLE and N O outputs are taken to normally open inputs of the intruder alarm system STAND ALONE ALARM The Interface p c b may also be used as a simple stand alone two zone alarm sys tem In this case normally closed switches may be wired in series these would pro tect for instance doors and windows and connected between the Alarm input and the positive power line with a pull down resistor of 22k taken from the input to OV see Fig 7a Note that normally closed refers to switches that are closed when the door for example is closed but open when the door opens The Duress input may s
194. ing off and adding panel labels getting prob lem projects to work including simple methods of fault finding In fact everything you need to know in order to get start ed in this absorbing and creative hobby Order code BP392 5 49 PRACTICAL FIBRE OPTIC PROJECTS R A Penfold While fibre optic cables may have potential advantages over ordinary electric cables for the electronics enthusiast it is probably their novelty value that makes them worthy of exploration Fibre optic cables provide an innovative interesting alternative to electric cables but in 138 pages 135 pages most cases they also represent a practical approach to the problem This book provides a number of tried and tested circuits for projects that utilize fibre optic cables The projects include Simple audio links F M audio link PW M audio links Simple d c links P W M d c link P W M motor speed control RS232C data links MIDI link Loop alarms R P M meter All the components used in these designs are readily available none of them require the constructor to take out a second mortgage Order code BP374 5 45 132 pages RADIO BYGONES We also carry a selection of books aimed at readers of EPE s sister maga zine on vintage radio Radio Bygones These books include the Comprehensive Radio Valve Guides five books with a Free copy of the Master Index for just 15 Also Jonathan Hill s excellent Radio Radio a comprehensiv
195. ink The 45mm x 45mm sheet of 16s w g aluminium shown on the drawing Fig 2 is sufficient for current drains up to 1A when the voltage drop across the regulators is not too extreme For larger current loads it is suggested that the heatsink be extended and bolted to the metal case or chassis of the unit to ensure adequate heat transfer Failure to properly dissipate heat from the regulators will result in the devices shutting down COMMISSIONING Once construction has been completed check the p c b for poor soldered joints and bridged tracks Check the orientation of elec trolytic capacitors diodes and regulators Make sure that the primary windings of the mains transformer are connected to suit the local supply voltage and that the sec ondary windings are connected in phase to deliver the correct voltage to the power supply p c b It is a good idea to connect the transformer to the mains and check the secondary voltage with a test meter before linking it to the p c b Extra care must be taken when carrying out this last task Check the voltage across the reservoir capacitor C5 and that the voltages deliv ered by regulators ICI and IC2 are cor rect before using the supply to power any equipment Everyday Practical Electronics July 2002 LOUDSPEAKERS Loudspeaker speaker designers have to make compromises Sensitivity good tran sient and good high frequency response call for a lightweight cone and speech coil a
196. ion Suitable for use with the Development Board shown above ASSEMBLY FOR PiCmicro V2 Formerly PiCtutor Assembly for PICmicro microcontrollers V2 0 previously known as PICtutor by John Becker contains a complete course in programming the PIC16F84 PlCmicro microcontroller from Arizona Microchip It starts with fundamental concepts and extends up to complex programs including watchdog timers interrupts and sleep modes The CD makes use of the latest simulation techniques which provide a superb tool for learning the Virtual PlCmicro micro controller This is a simulation tool that allows users to write and execute MPASM assembler code for the PIC16F84 microcontroller on screen Using this you can actually see what happens inside the PlCmicro MCU as each instruction is executed which enhances understanding Comprehensive instruction through 39 tutorial sections Includes Vlab a Virtual PlCmicro microcontroller a fully functioning simulator Tests exercises and projects covering a wide range of PlCmicro MCU applications Includes MPLAB assembler Visual representation of a PlCmicro showing architecture and functions Expert system for code entry helps first time users Shows data flow and fetch execute cycle and has challenges washing machine lift crossroads etc Imports MPASM files Virtual PiICmicro HARDWARE ee SOFTWARE C FOR PiCmicro VERSION 2 The C for PlCmicro microcontrollers CD ROM
197. ion life The original Stylo phone was a monophonic instrument which com prised a metal keyboard a stylus to play the notes vibrato and on off switches plus a line out socket There was also a spindle underneath for fine tuning Although there were only two basic models made there were many variants including the compo nents used and in the finish colour key board and packaging Dubreq licensed the Stylophone to America Germany France and Hong Kong Its major success though brought the inevitable copies and copyright infringements During its production life time approximately four million units were sold in the UK alone Developments in technology eventually caused the demise of the Stylophone in the early 1980s The simple electronics around which it was based were superseded by the far more sophisticated technology being used in instruments originating from the Far Fast Dubreq ceased manufacture in 1977 and was wound up in 1980 The original proto type Stylophone is said to still exist STYLOPIC CONCEPT Whereas the original Stylophone had 20 keypad zones the EPE StyloPIC has been extended to cover two full octaves 25 notes including sharps and flats C to C 261Hz to 1046Hz It too of course is activated by a stylus which makes contact with the integral keyboard style printed circuit board that also holds the electronic components Its tuning accuracy is superb the software making use of
198. ions provided including numerous step by step photographs 288 pages large format WOKE A N 14 99 MORE ADVANCED ROBOTICS WITH LEGO MINDSTORMS Robert Penfold Covers the Vision Command System Shows the reader how to extend the capabilities of the brilliant Lego Mindstorms Robotic Invention System RIS by using Lego s own accessories and some sim ple home constructed units You will be able to build robots that can provide you with waiter service when you clap your hands perform tricks see and avoid objects by using bats radar or accurately follow a line marked on the floor Learn to use additional types of sensors including rotation light temperature sound and ultrasonic and also explore the possibilities provid ed by using an additional third motor For the less experienced RCX code programs accompany most of the featured robots However the more adventurous reader is also shown how to write programs using Microsoft s VisualBASIC running with the ActiveX con trol Spirit OCX that is provided with the RIS kit Detailed building instructions are provided for the fea tured robots including numerous step by step pho tographs The designs include rover vehicles a virtual pet a robot arm an intelligent sweet dispenser and a colour conscious robot that will try to grab objects of a specific colour Order code BP902 298 pages ANDROIDS ROBOTS AND ANIMATRONS John Lovine Build
199. ior maths function that the PIC family lack yet which is often needed in a variety of appli cations next month TK3 Win2000 and WinXP Mark Jones has unravelled the secrets of getting our Toolkit TK3 programming software running under the Windows 2000 and XP platforms 511 Constructional Project ROTARY COMBINATION LOCK THOMAS SCARBOROUGH Pure logic and a stack of cards function helo to maintain the security of your cherished DOSSESSIONS HE purpose of this design is to f emulate as closely and as simply as possible the traditional rotary combi nation lock Full emulation would be possible with a complex design close emulation is possible with a remarkably simple circuit in this case using just two CMOS i c s and three transistors Pseudo rotary combination locks are well known These usually use a combined dial and pushbutton with limited rotation of the dial The dial is usually turned to a number in the sequence then a pushbutton is pressed to register the number Both this and the characteristics of the standard wafer rotary switch its rotation limit stop and snap action make such locks seem poor substitutes for the real thing This design has smooth 360 rotation does not use a pushbutton switch and offers roughly twice the security of a 4 digit keypad lock It also prevents aimless turning of the dial and is able to send a secret panic duress signal to another location
200. ir UHF colour television channels TELEBOX MB covers virtu ally all television frequencies VHF and UHF including the HYPERBAND as used by most cable TV operators Ideal for desktop computer video sys tems amp PIP picture in picture setups For complete compatibility even for monitors without sound an integral 4 watt audio amplifier and low level Hi Fi audio output are provided as standard Brand new fully guaranteed TELEBOX ST for composite video input type monitors 36 95 TELEBOX STL as ST but fitted with integral speaker 39 50 TELEBOX MB Multiband VHF UHF Cable Hyperband tuner 69 95 For overseas PAL versions state 5 5 or 6 mHz sound specification For cable hyperband signal reception Telebox MB should be con nected to a cable type service Shipping on all Telebox s code B State of the art PAL UK spec UHF TV tuner module with composite 1V pp video amp NICAM hi fi stereo sound outputs Micro electronics all on one small PCB only 73 x 160 x 52 mm enable full tuning control via a simple 3 wire link to an IBM pc type computer Supplied complete with simple working program and documentation Requires 12V amp 5V DC to operate BRAND NEW Order as MY00 Only 39 95 code B See www distel co uk data_my00 htm for picture full details HARD DISK DRIVES 21 2 14 2 TOSHIBA MK1002MAV 1 1Gb laptop 12 5 mm H New 59 95 2 2 TOSHIBA MK4313MAT 4 3Gb laptop 8 2 mm H New 105 00 2 2 TOSHIBAMK6409
201. ircuit board component layout full size copper foil master and lead off wires Check that 1 e d D2 is flashing The sole noid should at this point not have closed yet One of the most important aspects of setting up is to configure rotary switch S1 A 24 pin d i l socket two rows of 12 holes is used for this purpose with sheathed link wires being used to set the combination This is relatively simple to do and permits easy changing of the com bination at a later stage DOOR FRAME RETURN POSITION SPRING OF COVER ea T m pg SS e SS i a amp E a mi ka is a 5 l Completed prototype lock p c b and suggested combina Fig 4 Mechanical bolt arrangement using a solenoid tion display scaling above Everyday Practical Electronics July 2002 515 Alternatively 24 pin plug in sockets could be used to swap combinations in and out Twelve sheathed link wires are used with bared untinned ends each between 2cm and 4cm in length as required These are jumped across from Row A to Row B to set the combination For example suppose we want to set the first digit of the 4 digit code which is pin 5 of the 24 pin d i 1 socket pins 5 4 3 and 2 are used for the 4 digit code see Fig 1 Plug in a sheathed link wire at pin 5 Row A Next turn the rotary dial more or less to the position you would prefer for this fir
202. it which can be adapted Simple i c Power Amp modules left to right top to bottom from May 02 issue Single TDA2003 Amp Twin TDA2003 Amp 7DA7052 Amp TBA820M Amp LM380N Amp LM386N 1 Amp 500 for single or stereo pairs of any of the amplifiers described in Part 1 May 02 is given in Fig l The mains voltage is stepped down by transformer T1 and a full wave bridge rectifier arrangement D1 to D4 produces the d c output Reservoir capacitor C5 reduces supply ripple Voltage regulators IC1 and C2 virtually eliminate any voltage swings caused by load variations The regulators also remove any residual 100Hz ripple on the supply voltage rails and permit the use of a lower value reservoir capacitor C5 Low level electrical noise extending into the rf spectrum is present in the output of the 1 c s and bypass capacitors C6 C7 C8 and C9 shunt this to the OV rail The voltages required by amplifiers preamplifiers and auxiliary equipment are often different and provision is made for two regulated outputs Alternatively each output can supply a separate channel of a stereo system in order to double the current rating The switching action of the rectifier diodes D1 to D4 modulates any r f radio frequencies present in the mains input This modulated r f can be picked up by radio receivers connected to the supply and it manifests itself as a 100Hz hum which only appears when a s
203. k has been written as a designers guide covering many operational amplifiers serving both as a source book of circuits and a reference book for design calculations The approach has been made as non math ematical as possible Order code BP88 4 49 CIRCUIT SOURCE BOOK 2 R A Penfold This book will help you to create and experiment with your own electronic designs by combining and using the vari ous standard building blocks circuits provided Where applicable advice on how to alter the circuit parameters is provided The circuits covered are mainly concerned with signal generation power supplies and digital electronics The topics covered in this book include 555 oscillators sinewave oscillators function generators CMOS oscilla tors voltage controlled oscillators radio frequency oscillators 555 monostables CMOS monostables TTL monostables precision long timers power supply and regulator circuits negative supply generators and voltage boosters digital dividers decoders etc counters and dis play drivers D A and A D converters opto isolators flip flops noise generators tone decoders etc Over 170 circuits are provided which it is hoped will be useful to all those involved in circuit design and applica tion be they professionals students or hobbyists Order code BP322 5 45 160 pages 192 pages For a further selection of books see the next two issues of EPE 538 Project Building
204. ke an infinite number of possible levels Signals like this which are analogue in terms of levels but which only change value at specific points in time are called discrete time analogue signals the usual analogue signal as in Fig 9 3a is referred to as a continuous time analogue signal There are some types of circuit that directly process discrete time analogue 529 a Original waveform b Sampled and held version of a c Sampled at 1 3 sample frequen cy of b d Sampled at 1 6 sample frequen cy of b signals Perhaps the most well known of these are switched capacitor circuits which have several important uses includ ing filters Returning to the Nyquist sampling theo rem and looking at Fig 9 3 we conclude that waveform b is at a reasonable sam pling rate you can see that it resembles the original Waveform c is either two slow or very close to the minimum sample rate Waveform d is definitely too slow the sampled waveform bears little resem blance to the original If we only dealt with sinewaves it would be easy to ensure that we were sampling at the Nyquist rate but real signals are com plex and have a spectrum of frequencies present in them and we may not always be sure exactly what to expect In order to make sure that aliasing cannot lead to distortion of a converted waveform when using an ADC we often need to filter the signal to remove all frequencies above
205. ker the reply is likely to be and the more research that is needed the more you should offer to pay You could even apply online to be a Google researcher yourself though you shouldn t book an exotic holiday on the prospect of any rich rewards Some interesting new developments from Google are presently on show at http labs google com The most interesting one for EPE readers will be the new Google Glossary just type in an obscure acronym or phrase and Google will seek out a definition on the web A test for typical electronics terms including TTL mcu vlsi and CMOS rapidly returned definitions together with a corresponding lists of web sites Google Glossary is not America centric either it immediately defined HMCE Her Majesty s Customs and Excise and DVLA the UK s Driver and Vehicle Licencing Authority with b 909 yao oe E ag ihep a fee eter Everyday Practical Electronics July 2002 Google s Image Search will find and display a gallery of images that are published on the world wide web its usual speed Voice controlled searches by phone are also on the cards Other tools under development include Google Sets an interest ing attempt to return sets of terms that relate to a number of words or phrases that you enter This can be great fun to play with In the News One of the most important search functions provided is Google News http news google com This searches their entire archive
206. kman which is best for reducing sidelobes FFT size can be changed to between 128 and 4096 using the same menu option In addition you can change the display from dB to volts and display cur rent spectrum average spectrum or cap ture the spectrum peaks Finally the sampling frequency can be changed on the main display from a max imum of 10kHz to 100Hz The default is 10kHz The timebase option settings timebase F2 also allows you to change the frequency Spectrum Analyser Icon Tile ne x eco Y sal Aactangia Na of spe Trinagln Shee phage Hananing aliasing problems Try repeating Labs 9 3 and 9 4 with the filter in place Note that the filter has a cut off frequen cy of 4kHz and not 5kHz this is because the filter is not perfect and some energy is passed above the cut off frequency which would be aliased 1f it were set to half of the sampling frequency Also note that the cut off frequency should be changed if the sampling frequency is changed NEXT MONTH In Part 10 next month we conclude the Teach In 2002 series by discussing smart and intelligent sensors telemetry systems and sensor networks d c ACCURATE OUTPUT Q f DIVIDER VE FB RATIO IC1 LTC1062 o BUFFERED OUTPUT Fig 9 19 Anti aliasing filter having a cut off frequency of 4kHz 535 E TEACH IN 2000 CD ROM The whole of the 12 part Teach In 2000 series by John Becker published in EPE Nov 99 to O
207. lected from an object A con stant OV signal may indicate that the beam is reaching the sensor directly so try cov ering D1 and D2 with thick paper or Blu Tack front sides and back to find out whether this is the case Remember that when the circuit is housed in its case direct transmission from infra red e d s D1 and D2 to sensor IC1 should not be a problem A constant posi tive signal may indicate that the l e d s are not working at all Check their connections carefully and remember that the longer lead indicates cathode k on certain infra red e d s If you have employed only one l e d you should have fitted a wire link in place of the other one If the output pin 2 of ICI is working correctly its logic levels should be copied to pin 1 and pin 2 of IC2 Pin 3 of ICI should do the opposite The best test point on the monostable IC2b IC2c is pin 10 This should normal ly be around OV switching to positive during the timed period If its input side is working but the output fails check carefully the values of the components and whether diode D3 is fitted the correct way round If you have joined pads P1 and P2 then the timed period should be about 7 sec onds If the monostable never completes its timed period try using a smaller capacitor for Cl since some electrolytic capacitors leak current The value sug gested should not suffer in this way unless very old or connected the wrong way round If the volt
208. lides in and out of the front aperture protruding just so far as is required when actually playing the keyboard It is strongly recommended that the outer corners of the keyboard should be filed so that they are rounded and smoothed to avoid damage to your playing hand as it frantically keys out Tie me Kangaroo Down Sport or some other Rolfarian refrain or similar You may need to glue a wooden or plas tic support under the front of the keyboard area to prevent the board from tilting while playing If using an internal speaker the size of the above mentioned case would probably allow it to be mounted either under the lid or above the base with suitable holes drilled to let the sound out adequately A rotary volume control and jack socket for external sound output could be mounted on the rear panel along with switches S1 and 52 It seems likely that a PP3 battery will fit comfortably to the side of the p c b Those are just idle thoughts though let not the author impose his will on your creativity A word of caution though It is unusu al for a p c b to be used trackside upwards Do ensure that the tracks around the i c s cannot be shorted by inadvertent contact with anything con ductive However the keyboard tracks themselves may and must remain open and electrical shorts between them are permissible and unavoidable when play ing glissando It is also important that undesirable external voltage source
209. lished with the help of transistor TR1 which is wired as a stan dard inverter The purpose of capacitor C1 at TRI1 s base is to damp any possible mains tran sients since these may even pass through a regulated power supply One would not want to rouse a rapid reaction squad with a small mains transient from a hairdryer say The specified relays are rated at 60V d c 1A with a maximum switched power of 30W or 125V a c LA and a maximum switched power of 62 5VA This means that they may be used to switch powerful alarm sounders and bea cons directly so long as their ratings are not exceeded Alternatively they could be used to switch power relays which in turn could switch even bigger loads OBLIGATORY INHIBITION The Interface circuit includes a signif icant inhibition in the form of field effect transistor f e t TR2 Assuming that a would be thief would abandon the Rotary Combination Lock at the moment Everyday Practical Electronics July 2002 of triggering the alarm the rotary dial would then remain set to the Alarm posi tion and would thus continue to send trigger pulses to the Interface p c b In short the alarm would never stop sounding Local regulations will usually set a limit to the amount of time that a public alarm may sound In the UK this is 20 minutes Therefore when output pin 5 goes high capacitor C3 charges up through diode D1 the potential at TR2 s gate g rises and
210. list that are most commonly used in EPE projects In general compatibility between various TTL logic groups is not very good They have different supply volt age ranges logic voltage requirements drive currents and input currents Some are more tolerant of supply noise than others Unless you are sure you know what you are doing it is definitely not a good idea to use a device from the wrong logic family A substitute of this type will sometimes work but it is more likely to fail There is also a risk of the supply voltage being inappropriate for the sub stitute device which could result in it being damaged Tail Piece On the face of it the suffix is more crucial than the prefix These days most integrated circuits are available in a variety of case styles but only the dual in line d i l variety is normally used in do it yourself projects In practice there is less than total uniformity in the suffix es so what appears to be the wrong suffix can appear on a perfectly suit able device On the other hand an increasing range of surface mount devices is listed in most component catalogues so you have to be careful to order the right type The original 4000 CMOS devices had an AE suffix but the improved B series devices that are still in use today and have a BE suffix superseded these The E simply means that the device is in a plastic d i l encapsulation A few devices are available with a
211. llers V2 0 For further details see the CD ROMs for Electronics pages in this issue Weather Instruments IT is well known that in the UK we are pretty much obsessed with the weather Hardly surprising perhaps as despite the worthy efforts of our met forecasters it is so irrationally changeable and seemingly unpredictable Mindful of this no doubt American company Davis Instruments have sent a catalogue of their Precision Weather Instruments that will delight the heart of any weather watcher Davis Instruments is a California based manufacturer of high quality marine weather and automotive products They have a wide range of weather stations and accessories for many purposes from edu cation agriculture industry and expedi tions to just for the hobbyist The Weather Wizard III Station for exam ple is said to be everything you need for measuring inside and outside temperature wind speed and direction wind chill and daily and accumulative rainfall It is priced at US 250 although there are other units from 195 to 995 In the higher price range are included advanced stations that are solar powered and have radio links to a base station which can include a PC interface and a suite of analytical software For more information contact Davis Instruments 3465 Diablo Ave Hayward CA 94545 USA Tel 510 732 9229 Fax 510 732 9188 Web www davisnet com Also browse www sierracomm com and www icselectr
212. lling to cut a deal Instead after Zworykin visited Edouard Belin in 1928 and Farnsworth in 1930 Sarnoff set out to break Farnsworth s patents RCA had vast financial resources from the pool of several thousand radio patents the company had accumulated through the 1920s so could afford pro longed legal action with the best lawyers When Farnsworth won a round they just appealed In 1935 RCA had hardened its commitment to television instead of FM radio RCA s PR machine swung into action to tell the public what RCA was achieving At the World s Fair in New York in 1939 RCA made the headlines with Farnsworth and his sys tem nowhere to be seen Farnsworth s research had been starved of funds despite a deal with Bell and AT amp T in 1937 the inventor was on the breadline and in mental and physical decline Sarnoff was earning 100 000 a year In 1939 after ten years of legal battle RCA finally took a licence from Farnsworth the first ever for the company But war was coming and by the time it was over Farnsworth s patents were dead Ten years later ITT took over what was left of the Farnsworth company and the inventor lived on until 1971 dreaming up ideas for nuclear power generation Stashower s story makes a good read and a timely antidote to some of today s adverts for invention brokerage agencies which can lead the innocent into expect ing too much too easily from filing a patent But although the st
213. losses can be greatly reduced by winding the coils on short lengths of ferrite aerial rod Core saturation problems should not arise at the power levels encountered in domestic installations Bobbin construction is illustrated in Fig 4 Winding details for the inductor val ues likely to be encountered are given in Table 4 The wire should be wound on evenly and masking tape applied over each layer will make the task a little easier Constructors who have difficulty produc ing neat windings should increase the diameter of the bobbin ends for the larger inductance coils Capacitors The bipolar electrolytic capacitors used in crossover networks are available in a limited range of values Capacitors of this kind can be formed by connecting two ordinary electrolytics back to back and this makes possible the production of non standard values The details are given in Fig 5 Capacitors rated at 50V working Everyday Practical Electronics July 2002 CUT BOBBIN ENDS FROM 3mm HARDBOARD MASONITE IN USA USING A HOLE SAW IN AN ELECTRIC DRILL 13mm GLUE BOBBIN END TO PAPER TUBE CORE 60mm LENGTH OF 9 5mm DIA FERRITE ROD 50mm _ gt ROLLED AND GLUED PAPER TUBE 13mm O D Fig 4 Inductor bobbin construction details Table 4 Inductance of Ferrite cored Coils Induct 954 0 2 03 04 05 075 mH No of turns 45 60 75 90 100 125 1 1 5 2 2 5 3 3 5 150 175 200 225 250 275 Use 20 s w g
214. loud suitable for indoors or outdoors two tone 160mm x 135mm finished in white with bracket 4 99 Ref SIR2A FREEZER MAINS FAIL ALARMS Designed to fit around the mains cable on a freezer this alarm will sound if the device is unplugged from the mains supply battery operated cased built in sounder Ideal for TVs Hi Fi equipment etc 7 01 Ref FRE2 BARNET CROSSBOWS We stock the entire range of crossbows check out our web site at www xbows co uk HOT AIR BALLOON KITS Everything you need to build a 1 7m high 4 5m in circum hot air balloon launch over a small burner or heater 12 49 Ref HA1 CROOKES RADIOMETER Fascinating glass bulb contains blades driven around by the sun 9 99 Ref SC120B GIANT TV OR PC VIEWING SCREEN Turn your TV into a super size screen converts small screens into a super size 26in 26 99 Ref SVGA2 RADIOSONDES Made by Valsala unused they measure pres sure temperature and humidity Model RS80 good stripper at 15 Ref SONDE AIR WIND POWER MODULE Produces nearly 400 watts of power from the wind 1 14m blade 12V d c output 3 year war ranty built in battery regulator 549 Ref AIR1 WORMERIES The ideal solution for your kitchen waste Supplied complete with worms Turn your rubbish into liquid feed Two sizes available small ideal for 1 2 people 25 45 Ref WM2 and a large one ideal for 4 or more 42 44 Ref WM1 COMPLETE WIRELESS CCTV SYSTEM Includes monitor cam
215. lude in your own programs Ideal development base for meters terminals calculators counters timers Just waiting for your application PIC 16F84 MAINS POWER 4 CHANNEL CONTROLLER amp LIGHT CHASER WITH PROGRAMMED 16F84 AND DISK WITH SOURCE CODE IN MPASM ZERO VOLT SWITCHING MULTIPLE CHASE PATTERNS OPTO ISOLATED 5 AMP OUTPUTS 12 KEYPAD CONTROL SPEED DIMMING POT HARD FIRED TRIACS Kit 855 39 95 8 CHANNEL DATA LOGGER As featured in Aug Sept 99 EPE Full kit with Magenta e PCB LCD fits directly on board Use as Data ogger or as a test bed for many other 16F877 projects Kit a udes programmed chip 8 EEPROMs PCB case and all components KIT 877 49 95 inc 8 x 256K EEPROMS ICEBREAKER oo0o0000000 INCLUDES 1 PIC16F84 WITH DEMO PROGRAM SOFTWARE DISK PCB INSTRUCTIONS AND 16 CHARAC TER 2 LINE LCD DISPLAY Now features full 4 channel chaser software on DISK and pre programmed PIC16F84 chip Easily re programmed for your own applica tions Software source code is fully commented so that it can be followed easily LOTS OF OTHER APPLICATIONS PIC Real Time In Circuit Emulator Icebreaker uses PIC16F877 in circuit debugger Links to Standard PC Serial Port lead supplied Windows 95 Software included Works with MPASM and MPLAB Microchip software 16 x 2L C D Breadboard Relay I O devices and patch leads supplied As featured in March 00 EPE Ideal for beginners AND advan
216. mber No multiplier band is used with this system There should be no diffi culty with this type of coding provided you know the resistor colour code 523 EPE IS PLEASED TO BE ABLE TO OFFER YOU THESE ELECTRONICS CD ROMS ELECTRONICS PROJECTS Electronic Projects is split into two main sections Building Electronic Projects contains comprehensive information about the components tools and techniques used in developing projects from initial concept through to final circuit board production Extensive use is made of video presentations showing soldering and construction techniques The second section contains a set of ten projects for students to build ranging from simple sensor circuits through to power amplifiers A shareware version of Matrix s CADPACK schematic capture circuit simulation and p c b design software is included The projects on the CD ROM are Logic Probe Light Heat and Moisture Sensor NE555 Timer Egg Timer Dice Machine Bike Alarm Stereo Mixer Power Amplifier Sound Activated Switch Reaction Tester Full parts lists schematics and p c b layouts are included on the CD ROM Logic Probe testing ELECTRONIC CIRCUITS amp COMPONENTS V2 0 Provides an introduction to the principles and application of the most common types of electronic components and shows how they are used to form complete circuits The virtual laboratories worked examples and pre designed circuits allow students to learn experiment an
217. mely long memories Any attempt to pass off a deliberately copied circuit as original will be exposed without mercy both by upset readers as well as EPE NOTE The Emergency Light circuit in the May 2002 issue which is original was sent in by Thomas Scarborough 80 078 Mains PSU 220 2404 AC input 15V DG 800mA output Plug in the wall hoe am flying kad to a 2 1mm power 80 045 12V 174h lead acid sealed rechargeable battery Gel type Brand new 180 x 165 x 75mm These are On off and zero button inside and outside messunng plus locking screw to hold measurement Uses a standard watch battery included Metal construction Supplied in a neat plastic storage case 4 95 80 042 Switch mode PSU ATX type for computers Mains input to OC output 5V 37A43 9V 25A 412V WHS5A 5V E 048 12V 0TA 5 aux 0 754 maximum 330W Made by AG Bel Part No API7506 Case size 160 x 145 x 105mm Fan cooled 12 95 60 082 Test leads with crocodile clips 4mm plug one end to an insulated crocodile clip the other One red and one black 200mm long 1 00 48 077 AA size Nickel Metal Hydride rechargeable battery 1 2V 1200m Ah with nipple Brand new 1 75 38 403 Pack of 3 AA Ni Cads 650m soldered togather with a 2 lead toa 2 pin socket giving them a total of 3 64 650mA You could split them up or join them together Only 1 25 56 095 AAA rechargeable Ni Cads 240 mAH Supplied on cards of
218. miconductor LM13600 transconductance amplifier i c and the SGS Thompson L272 dual power op amp i c only appear to be listed by RS codes 304 453 and 635 167 respectively You can order Everyday Practical Electronics July 2002 them direct from RS credit card only on amp 01536 444079 or on the web at rswww com A post and handling charge will be levied The above company supplied the Texas TLC7524CN 8 bit digital to ana logue converter chip code 650 087 It is also currently listed by Rapid amp 01206 751166 or www rapidelectronics co uk code 82 0764 but double check it is the 16 pin device being supplied For those readers unable to program their own PICs a ready pro grammed PIC16F877 20 microcontroller can be purchased from Magenta Electronics 01283 565435 or www magenta2000 co uk for the inclu sive price of 10 each overseas add 1 p amp p It is the 2OMHz version you require The software is available on a 3 5in PC compatible disk EPE Disk 5 from the EPE Editorial Office for the sum of 3 each UK to cover admin costs for overseas charges see page 539 It is also available Free from the EPE web site ftp ftp epemag wimborne co uk pub PIC StyloPIC The printed circuit board keyboard is available from the EPE PCB Service code 359 see page 539 Simple Audio Circuits 3 Most of our components advertisers should be able to supply all the parts needed to construct the circuits in this month s instalment
219. mplete with camera 20 metres of cable p s u and info simple connection to scart 24 99 Ref CCTVCAN2 FM BROADCAST BAND HIGH POWER TRANSMITTERS can be viewed and bought online at www veronica kits co uk TONER CARTRIDGES FOR COPIERS AND PRINTERS can be bought online at www nationaltoners co uk VELOSOLEx Traditional French style two stroke moped engine over front wheels black only 695 Ref VELO Delivered direct in a box you need to fit the pedals etc then register it with your local DVLC HYDROPONIC GROWING SYSTEMS Complete everything you need apart from plants and light contains grow tank nutrients pump tester etc GT205 710mm x 390mm NFT system 31 45 Ref GT205 GT424 1070mm x 500mm NFT system 58 65 Ref GT424 ELECTRIC BIKES 679 Viking built in indicators radio lights 13mph 5 hour charge Shimano gears up to 50 mile range horn 26in wheels suspension no licence needed key operated 679 Ref VIKING PIR PCBs These contain a standard PIR detector circuit with all components easy to wire up and use Pack of 4 6 Ref PIR8 NEBULISER WATER ATOMISER Ultrasonic module that you place in water atomises the water into a very fine mist many applications from special effects to scientific 69 Ref NEB6 PORTABLE X RAY MACHINE PLANS Easy to construct plans on a simple and cheap way to build a home X ray machine Effective device X ray sealed assemblies can be used for exper imental purposes N
220. much wider band width than transmitting the analogue signal directly We will use the transmission of speech as an example Human speech has frequency components up to 10kHz but we can reduce the bandwidth to around 3 4kHz without reducing the overall intelligibility This 3 4kHz is the bandwidth of common analogue telephones In order to turn the signal into a digital form we need to sample it According to the Nyquist sampling criterion the mini mum rate is 6 8kHz However a higher value of 8kHz is used since the anti alias ing filter will not have an infinite roll off Once sampled the signal is then converted into digital form using an ADC The small est number of levels needed to give good quality is around 200 and an 8 bit ADC has 256 levels We now have a signal sampled 8 000 times per second and converted into 8 bit samples This gives 8 x 8 000 bits per sec ond 64 000 bits per second A transmis sion path needs to have a bandwidth at least 64kHz to accommodate this Compare this with the original of 3 4kHz we need near ly 19 times the bandwidth RADIATION SENSING Our main sensing topic this month is nuclear radiation Obviously we won t be able to carry out any experiments but we can look at the principles of nuclear radia tion and how it can be measured Before discussing sensors we need to examine the causes of nuclear radiation All elements are made up of a nucleus surrounded by a cloud of negatively
221. n by soldering in posi tion the 14 pin i c socket followed by the resistors and diodes D3 and D4 checking that the diodes are fitted the correct way round Now fit the larger components includ ing bridge rectifier REC1 and the capac itors Again all must be fitted the correct way round except C2 which may be either way Fit transistor TR1 with its metal tab away from the edge of the board and regulator IC3 with the flat side the way shown Fit solder terminal pins into copper pads P1 and P2 or use a wire link which will later be cut to join these two pads togeth er This will help with testing as explained later The infra red 1 e d s D1 and D2 must be fitted the correct way round see Fig 3 and must stand proud of the board so that they may be bent over the edge later Leave their wires as long as possible Everyday Practical Electronics July 2002 SOND toe wn tis oO TAGE viny I orhiesping Axyso009 Component layout on the completed printed circuit board The infra red sensor and diode emitters are mounted on the lefthand edge Note the two infra red light emitting diodes are looped over the edge of the p c b WARNING The IR e d s used in the prototype were supplied with their longer leads indicating cathode k This is very unusual normally ong indicates anode a So take care with the orientation of the Le d s Round l e d s have a flat mark on the base of the plastic
222. n evaluation copy of Paint Shop Pro 3 0 may be downloaded from www jasc com and works just as well although the toolbars are better on V4 15 Other graphics packages may work with the following procedure but I have no such experience Maybe other readers can advise Install PSP open to full screen size and minimise Open Acrobat to full screen size load the relevant p c b layout page and cen tralise the layout on the screen Press the Print Screen key on the keyboard this sends the screen image to the clipboard Minimise Acrobat and maximise PSP and make it the active window Press Ctrl V simultaneously which pastes the clip board to PSP Select the p c b layout crop and zoom to 10 1 A bit map image in pixels is produced which may be manipulated in all forms Pixels can be deleted or added as required DIGITAL MULTIMETER Dear EPE Could you please send me any information you might have on digital multimeters I am building a multimeter and I heard your magazine did an issue several years ago I do not have this particular magazine and you not do back issues Thank you for your support and great magazine Meme via email We have not done anything on them in many years and cannot offer you any info However they are so cheap that it seems hardly worthwhile building one But why do you believe we do not sell back issues We certainly do as our regular Back Issues pages prove We also sell back issues on CD ROMs
223. n origin adopt a crossover frequency of around 2 5kHz this will normally be satisfactory When the bass speaker is large 12 inch es diameter or more a crossover at 1kHz or even lower can produce a more even fre quency response Suitable tweeters tend to be rather costly but an inexpensive alterna tive will be described later THREE SPEAKERS Another way of ensuring a more even response when a large bass speaker is used is to install a third mid range unit Suitable circuits are given in Fig 3d and Fig 3e The bass mid range crossover point is usually around 500Hz with open chassis mid range speakers and 1000Hz with sealed back units The mid range treble crossover is generally between 4 5kHz and 6kHz Again the recommendations of the speaker manufacturer should be followed PHASING Parallel connected bass speakers must be wired in phase to avoid cancellation of the lower audio frequencies Use a 1 5V dry cell to test for phasing on unmarked speakers by noting the battery positive con nection for the outward movement of the cone Crossover networks introduce phase shift but as frequency increases phasing becomes less important Readers can try reversing the connections to mid range units However unless they have a very refined ear they are not likely to detect any difference CROSSOVER COMPONENTS Inductors Inductors for home made crossovers have to be hand wound The amount of wire and the resistive
224. n the Alarm input and OV This means that monostable Cla would continually be triggering and the alarm would always be sounding if TR2 were not there to inhibit incoming negative going pulses Then the anode of D1 should be disconnected from its existing position and connected to ICI pin 9 instead A hole is provided for this purpose on the p c b at the junction of R8 and R9 see Fig 6 Now every time a Duress pulse is received the Alarm trigger is disabled If however no Duress pulse is received TR2 s Inhibit feature times out mono stable Cla triggers and RLA pole contact switches over to the normal open contact sounding the alarm The Duress input may be tied low with a 22kQ resistor and a nor mally open switch perhaps a lever switch wired between the input and the positive line to operate the dead man s handle All that now remains is for you to decide how soon you would like the alarm to sound after the unit has been abandoned this is determined by capacitor C3 see earlier and how long you would like the alarm to sound which is set by VR1 Adjust preset VR2 to its minimum value since IC1b merely serves as a trigger in this application Switch S1 serves to instantly cancel the alarm CONDITIONAL SWITCH A conditional switch is one which switches on condition that another switch has or has not been activated during a predetermined period beforehand This would have a wide variet
225. ncy front end single chip AM radio IC amp 2 stages of audio amplification All components inc speaker provid ed PCB 32x102mm 3063KT 10 95 DRILL SPEED CONTROLLER Adjust the speed of your electric drill according to the job at hand Suitable for 240V AC mains powered drills up to WEB http www QuasarElectronics com email epesales QuasarElectronics com SURVEILLANCE High performance surveillance bugs Room transmitters supplied with sensitive electret microphone amp battery holder clip All transmit ROOM SURVEILLANCE MTX MINIATURE 3V TRANSMITTER Easy to build amp guar anteed to transmit 300m 3V Long battery life 3 5V operation Only 45x18mm B 3007KT 6 95 AS3007 11 95 MRTX MINIATURE 9V TRANSMITTER Our best selling bug Super sensitive high power 500m range 9V over 1km with 18V supply and better aerial 45x19mm 3018KT 7 95 AS3018 12 95 HPTX HIGH POWER TRANSMITTER High performance 2 stage transmitter gives r ike greater stability amp higher qual ity reception 1000m range 6 12V DC operation Size ja 70x15mm 3032KT 9 95 E AS3032 18 95 MMTX MICRO MINIATURE 9V TRANSMITTER The ultimate bug for its size performance and price Just 15x25mm 500m range 9V Good stability 6 18V operation 3051KT 8 95 AS3051 14 95 VTX VOICE ACTIVATED TRANSMITTER Operates only when sounds detected Low standby current Variable trigger sen sitivity 500m range Peaking circuit supplied fo
226. nd a RTTY serial to parallel converter A full range of interesting and useful circuits for short wave enthusiasts Order code BP304 4 45 92 pages AN INTRODUCTION TO AMATEUR RADIO I D Poole Amateur radio is a unique and fascinating hobby which has attracted thousands of people since it began at the turn of the century This book gives the newcomer a com prehensive and easy to understand guide through the subject so that the reader can gain the most from the hobby It then remains an essential reference volume to be used time and again Topics covered include the basic aspects of the hobby such as operating procedures jar gon and setting up a station Technical topics covered include propagation receivers transmitters and aerials etc Order code BP257 5 49 150 pages VALVE RADIO AND AUDIO REPAIR HANDBOOK Chas Miller This book is not only an essential read for every profes sional working with antique radio and gramophone equipment but also dealers collectors and valve tech nology enthusiasts the world over The emphasis is firm ly on the practicalities of repairing and restoring so technical content is kept to a minimum and always explained in a way that can be followed by readers with no background in electronics Those who have a good grounding in electronics but wish to learn more about the practical aspects will benefit from the emphasis given to hands on repair work covering mechanical as well as electr
227. nd the 12V line if desired so that the lock may be closed again with a button press Thus this lock could be used for example to open a door and the pushbutton switch used to reset the lock after entering The specified solenoid consumes nearly 10W and this means that a 12V 1A power supply is required The solenoid could also be replaced with a relay if this would bet ter suit the requirements of the application Although the solenoid is rated for a contin uous 12V with the prototype it was found that after 15 minutes or so it generated an uncomfortable amount of heat it is sup posedly permitted to warm to 105 C If the lock is likely to remain opened solenoid active for long periods a simple modification to the circuit can be made as shown in Fig 2 This changes the lock from one that simply opens to one that briefly releases A tapered plunger may then be used to click the lock shut This arrange ment may be used also where only a small er 12V power supply 100mA upwards is to hand Note that diode D8 in the OV line which prevents reverse polarity power supply connection warms as well when the lock is opened and this is normal If desired a number of solenoids may be wired in parallel In this case separate MOSFETs must be used in place of the single one used as TR3 and their gates are commoned The power supply s rating must be suitably increased as well as the rating of diode D8 514 COMPO
228. ndor you may know as Radio Shack or Tandy You will see RS Components part numbers quoted frequently in our con structional articles as well as in Shoptalk RS Components http rswww com is a vast UK based component supplier that over the years has built up an excellent reputation for delivering a high quality service to industry Even so the information you received from RS Components was incorrect A very apologetic RS advisor confirmed that although they are strictly speaking a trade only organisation they are still happy to deal with individuals on a credit card basis only They were keen to phone you to sort out your order Readers should note that the only other way to buy from RS is via their web site which is what I do if I need an RS part in a hurry I suggested you give RS another try this time asking for the New Customer Reception department if you have any fur ther problems ARW Everyday Practical Electronics July 2002 Video Surveillance C MOS B W Camera 15mm 15mm 29 00 C MOS Colour Camera 15mm 15mm 65 00 PCB B W Camera 32mm 32mm 24 00 PCB Colour Camera w Audio 32mm 32mm 65 00 23cm 1 3GHz Video Audio Transmitter 35 00 13cm 2 4GHz Video Audio Transmitter 35 00 1 2 Watt 2 4GHz Video Audio Transmitter 120 00 4 TFT Boxed Colour Monitor w Audio 110 00 Video to VGA Converter 65 00 VGA to Video Converter 90 00 External USB Video Capture Box 55 00 All prices exclude VAT M
229. nsistor TR1 which now con ducts TR1 ensures that the u j t oscillator Fig 2 Minor circuit change for releas ing the lock DURESS 4 DIGIT CODE OV INTERFACE UNIT R2 Fig 1 Circuit diagram for the Rotary Combination Lock Note how positive pulses are routed through the 12 way rotary switch S1 via the 24 pin combination d i l socket Everyday Practical Electronics July 2002 513 is not unduly loaded and also that no neg ative going pulses will reach the circuit and so unbalance it SOLENOID The solenoid is powered by power MOSFET TR3 which conducts when the potential at its gate rises above about 4V as provided by the output of IC2d When IC2d latches TR3 conducts and the sole noid retracts with a convincing whack The solenoid s integral spring enables the lock to close again when the circuit receives a Reset pulse from switch S1 The specified MOSFET has an extreme ly low on resistance 0 040 and this ensures that there is minimal power dissi pation in the device and therefore minimal generation of heat In fact TR3 remains cool without any heatsinking Note that TR3 should not be substituted with any old power MOSFET since a power MOSFET with a higher on resis tance will dissipate more power thus gen erating more heat which would then need the use of a suitable heatsink A momentary action pushswitch may be wired between Cla pin 13 a
230. nts advice on construction and guid ance on setting up and using the projects this invaluable book will save you a small fortune Circuits include video enhancer improved video enhancer video fader horizontal wiper improved video wiper negative video unit fade to grey unit black and white keyer vertical wiper audio mixer stereo headphone amplifier dynamic noise reducer automatic fader pushbut ton fader computer control interface 12 volt mains power supply 01e 1o H nd Om Iu Eo 10 95 124 pages PC MUSIC THE EASY GUIDE Robin Vincent How do make music on my PC Can record music onto my PC What s a sequencer How can get my PC to print a music score What sort of a soundcard do need What hardware and software do need How do connect a key board to my PC Just a few of the questions you ve probably asked Well you ll find the answers to all these questions and many more in this book It will show you what can be done what it all means and what you will need to start creating your own music on your PC It s an easy read it s fully illustrated and it will help you understand how a computer can be used as a creative music tool It covers soundcards sequencers hard disk digital audio recording and editing plug ins printing scores with notation software using your PC as a synthesiser getting music onto and off the Internet using Windows sample PC music set ups FAQs a glossary a
231. o in which the two end surfaces are in strong mag netic connection to each other The other ends have rigid wires attached to enable the mag nets to be p c b mounted so that they make strong electrical and physical contact with fer rous based components such as fuses and some types of battery casing for instance They really have an extremely powerful semi permanent bonding effect allowing components to be securely retained yet removed from a circuit without desoldering They can even pick up two D type batteries weighing in at 300g The Magtrix connectors can also be used as the component part of actuators Hall effect devices and generators It seems that they must have many more applications in a hobbyist s workshop as well They are supplied as five pairs to a pack code MC 53GNS for 3 75 For more information contact Magtrix Connectors Dept EPE 17 Larch Drive Brinscall Chorley PR6 8QN Tel 01254 830761 Fax 01254 830408 Email sales victorignition co uk Magnifico FOR a bigger view of those tiny electronic components and their identities you should look into Magnifico UK Ltd They tell us they offer Britain s best online selection of magnifiers loupes and low vision aids On their website are over 100 products in six key categories including handheld illuminated desk sheet and handsfree There is also a useful guide Choosing A Magnifier to help with your selection Prices range from 2
232. o noise ratio is lower A digital signal also has a lower SNR but as long as it can still be detected as a logic 1 high voltage it can be recon structed a method known as regenera tion This becomes important when very long cables are used such as undersea telephone cables for example Digital signals can be processed many ways in microcontrollers and specialized digital signal processors DSPs when the equivalent analogue circuits would be extremely complex Just think how 528 many op amps would be needed for a low pass filter with a roll off of 240dB per octave at one op amp per 24dB we would need 10 op amps plus 40 resistors and 20 capacitors It is possible to implement such a filter in digital form using arithmetic on a DSP Digital signals can be stored in memory whereas analogue signals cannot easily be stored unless on tape Digital signals can be encrypted against interception and in theory can be made totally secure Analogue signals can only be scrambled i e the spectrum and or the time domain waveform is mixed up and reconstructed when received Scrambling is not secure since many of the signal s characteristics e g speech are preserved and it is relatively easy to unscramble Digital signals are not always good though especially if we are going to trans mit them over for example radio because they need a much wider bandwidth than the original analogue signal This so called band
233. oblems The first zapper circuit I built was Hulda s original from her book It has a truly horrible 496 output waveform and ran at about 18kHz if I recall I used the bipolar 555 in case the rise and fall times of the output were significant being faster than CMOS types However I ve since found that the body appears to behave a bit like a capacitor if the output drive current isn t avail able it ll slow the rise and fall times significant ly Hulda s design has a 1kQ resistor in its output which would be enough to cause the problem Frequencies I ve used both and didn t notice any significant difference between them One commercial supplier now claims that they work by achieving resonance with the target organisms and bursting them but I think there s some confusion with Rife here They offer a unit which sweeps its output between 10kHz and 100kHz though if it s swept as fast as their scope picture suggests it misses most of the intermediate ones Yes we should have had warnings Andy Flind PIC INTERRUPTS Dear EPE Referring to Malcolm Wiles Using PIC Interrupts articles Mar Apr 02 the RETFIE instruction is by no means the only possible return from an ISR RETURN and RETLW can also be used but will not set the GIE bit This proved useful to me on one occasion when I needed to measure the width of an external pulse The ISR in conjunction with TMRO mea sured the pulse width
234. oes not converge PRACTICALITIES In practical terms though manual inspection and iteration during program development is at the very least tedious and time consuming At worst it can be highly error prone Each time a program is modified you need to repeat the fix up process and on subsequent occasions the chances are that you have mostly forgot ten how large chunks of the program work in detail Everyday Practical Electronics July 2002 Alternatively every relevant instruction that might involve page boundaries could be preceded by PCLATH setting instruc tions whether they are needed or not a brute force approach Whilst it can be argued that it would be cumbersome and consume valuable program memory space to set PCLATH for every such instruction there is a lot to be said for the brute force approach if programming space permits it and there are doubts about where page boundaries might lie The use of PCLATH is essential in many larger PIC programs and it is a command that you should familiarise yourself with through experiment Perhaps the best advice is to use it in a fashion you feel comfortable with and which you have proved through experimentation to be reli able While evolving that technique remember that you have to keep your wits about you but then don t you always in programming STRUCTURED PROGRAMMING Program structure whether in the PIC language or a high level language is the pro
235. on Ic equipment UNDERPINNING KNOWLEDGE Specific sections enable you to Understand Electrical oA d 900 and Electronic Principles Active and Passive Components Circuit Diagrams Circuit QUN P ages Measurements Radio Computers Valves and Manufacturers Data etc e Fundamental principles PRACTICAL SKILLS Learn how to identify Electronic Components Avoid Static Troubleshooting techniques Hazards Carry Out Soldering and Wiring Remove and Replace Components e Servicing techniques e Choosing and using test TEST EQUIPMENT How to Choose and Use Test Equipment Assemble a Toolkit Set Up a Workshop and Get the Most from Your Multimeter and Oscilloscope etc SERVICING TECHNIQUES The regular Supplements include vital guidelines on how to Service Audio Amplifiers Radio Receivers TV Receivers Cassette Recorders Video Recorders Personal Computers etc TECHNICAL NOTES Commencing with the IBM PC this section and the regular Supplements deal with a very wide range of specific types of equipment radios TVs cassette recorders amplifiers video recorders etc REFERENCE DATA Detailing vital parameters for Diodes Small Signal Transistors Power Transistors Thyristors Triacs and Field Effect Transistors Supplements include Operational Amplifiers Logic Circuits Optoelectronic Devices etc ELECTRONICS SERVICE MANUAL ESM Printed version only Basic Work Contains around 900 pages of information Edited by Mike Tooley BA R
236. onics co uk icsnet Everyday Practical Electronics July 2002 Greenweld e E bargains GREENWELD Electronics who are noted for their bargain offers tell us that their E Newsletters may become a more regular item thanks to a new member of staff who has got it into her head that we ought to actually tell all our customers about the latest bargains when they come in instead of just sitting here drooling over them So readers get yourselves on Greenweld s E newslist and get to the bar gains before they are snapped up by those just sitting at home waiting for the postman to deliver news about them through snail mail For more information email bargains greenweld co uk or browse www greenweld co uk Networks Expo NETWORKS Telecom Europe 2002 takes place at Birmingham NEC from 25 to 27 June 2002 and provides a platform to explore new products network with leading vendors and keep abreast of the latest issues facing the networking industry There will be over 200 exhibitors offer ing demonstrations and advice relating to new products and services For more information visit www networks telecom com Attractive Connections THE new Magtrix Connectors caused a bit of a stir on the newsdesk They are mag netic and are said to be an irresistible con nection Indeed so for their size they probably have the strongest permanent magnet we ve encountered A pair of them is shown in the phot
237. ork per fectly well Approx Cost Guidance Only 40 excluding batts INTERFACE MODULE Resistors R1 to R3 100k 3 off R4 R7 4k7 2 off R5 470Q R6 220k R8 R10 1k 2 off R9 R11 22k 2 off All 0 25W 5 carbon film Potentiometers VR1 VR2 1M cermet preset 2 off Capacitors C1 100n min polyester C2 C4 C5 220u sub min radial elect 16V 3 off C3 1u sub min radial elect 16V C6 100u sub min radial elect 16V Semiconductors D1 D4 D5 1N4148 signal diode 3 off D2 red l e d 3mm D3 green l e d 3mm D6 1N4001 50V 1A rect diode TR1 BC337 npn transistor TR2 2N3819 f e t transistor TR38 TR4 BC547 npn transistor 2 off IC1 7556 dual CMOS timer Miscellaneous RLA RLB ultra min s p c o relay 12V low power p c b mounting 2 off S1 min s p s t pushswitch p c b mounting Printed circuit board available from the EPE PCB Service code 361 14 pin d i l socket connecting wire solder pins solder etc Remove the switch s rotation limit washer and clip off its tab Carefully prise open the switch observing where each part fits To cancel the snap action of the switch so that it will rotate smoothly take out the spring and the two ball bearings if they have not shot out already The author opens up such items inside a glass jar the pieces can be awfully hard to find if they shoot into the air Internally there is a rotation limit stop which is an integral p
238. ors including worksheets multiple choice tests fault finding exercises and examination questions FILTERS Filters is a complete course in designing active and passive filters that makes use of highly interactive virtual laboratories and simulations to explain how filters are designed It is split into five chapters Revision which provides underpinning knowledge required for those who need to design filters Filter Basics which is a course in terminology and filter characterization important classes of filter filter order filter impedance and impedance matching and effects of different filter types Advanced Theory which covers the use of filter tables mathematics behind filter design and an explanation of the design of active filters Passive Filter Design which includes an expert system and filter synthesis tool for the design of low pass high pass band pass and band stop Bessel Butterworth and Chebyshev ladder filters Active Filter Design which includes an expert system and filter synthesis tool for the design of low pass high pass band pass and band stop Bessel Butterworth and Chebyshev op amp filters Filter synthesis ELECTRONICS CAD PACK PCB Layout Electronics CADPACK allows users to design complex circuit schematics to view circuit animations using a unique SPICE based simulation tool and to design printed circuit boards CADPACK is made up of three separate software modules These are restricte
239. ory hangs on patents they are not identified by num ber this is a surprising omission It is also clear that the author is much better at telling a story than analysing and explaining competing technologies He would have benefited from some techni cal assistance And I would add a final irony some of the original mechanical technology has recently found a new life the digital micro mirror projectors which use a Texas Instrument chip often rely on a spinning filter wheel to add colour to the picture WELLBERRY CASES MOST of you are no doubt familiar with the WB range of project cases that has been around for many years Wellberry Cases have remind ed us that in fact it was in 1971 that these aluminium steel cases with simulated leatherette texture finish were first introduced In 1974 the same company also introduced the familiar EB range that so many read ers have used for instrumentation type housings The good news is that not only are the cases still available after all these years but that they are now available direct from the manufactur er Wellberry at a good price advan tage Not only that Wellberry will also punch panels to your design if you have a requirement for at least 50 of them kit suppliers take note and at a low price For more information contact Wellberry Cases Dept EPE lon Farm Lower Gravenhurst Bedford shire MK45 4HH Tel 01462 814788 Fax 01525 860081 Web www wellberry
240. ot a toy or for minors 6 set Ref F XP1 TELEKINETIC ENHANCER PLANS Mystify and amaze your friends by creating motion with no known apparent means or cause Uses no electrical or mechanical connections no special gimmicks yet produces positive motion and effect Excellent for science projects magic shows part demonstrations or serious research and development of this strange and amazing psychic phenomenon 4 set Ref F TKE1 ELECTRONIC HYPNOSIS PLANS amp DATA This data shows sev eral ways to put subjects under your control Included is a full vol ume reference text and several construction plans that when assembled can produce highly effective stimuli This material must be used cautiously It is for use as entertainment at parties etc only by those experienced in its use 15 set Ref F EH2 GRAVITY GENERATOR PLANS This unique plan demonstrates a simple electrical phenomena that produces an anti gravity effect You can actually build a small mock spaceship out of simple mate rials and without any visible means cause it to levitate 10 set Ref F GRA1 TESLA COIL LIGHTNING DISPLAY GLOBE PLANS Produces up to 750 000 volts of discharge experiment with extraordinary HV effects Plasma in a jar St Elmo s fire corona excellent science project or conversation piece 5 set Ref F BTC1 LG5 COPPER VAPOUR LASER PLANS Produces 100mW of visible green light High coherency and spectral quality similar to argon laser but easier
241. ounter that is output to Port A and DAC IC2 Listing 2 shows the structure of the PLAYIT routine There are two points especially worth noting in Listing 2 First it will be seen that the status of the Carry flag is not actu ally tested e g BTFSS STATUS C but its status is extracted as a value which is then added to WAVEHI regardless of whether the answer is 0 or 1 One of the most import aspects of music generation software is that all functions are absolutely consistent in their timings irrespective of any intermediate actions that have to be performed during them To have actually tested the Carry flag would have resulted in different loop timings depending on the result of the test This would probably be heard as a brief hiccup unevenness in the note The process shown in Listing 2 avoids this brief deviation Secondly it is in the PLAYIT routine that the output waveform is set to either ramp or squarewave Towards the end of Listing 2 is the command BTFSC MASK 0 Register MASK is that which holds the waveshape flag as triggered by touching the stylus on the keyboard s right hand pad marked with a triangle and squarewave below it If MASK bit 0 is set 1 then the ramp waveform is required and the routine jumps to label PLAY2 and then at OUTIT outputs the full value of the OUTPUT counter to Port A If MASK bit O is not set 0 the Squarewave output is required This is gen erated by outputting a valu
242. pacitor C1 reactances at the bass mid range cross over frequency equal to the rated speaker impedance 2 Make inductor L2 and capacitor C2 reactances at the mid range treble cross over frequency equal to the rated speaker impedance Low frequency roll off above the crossover frequency is 6dB per octave and this may not be sufficient to protect some tweeters when higher powered amplifiers are used In these cases the second order filters shown in Fig 3b and Fig 3e which produce a 12dB roll off are safer options merr o MID RANGE SECOND ORDER NETWORK THREE SPEAKER SYSTEM 1 Calculate inductor and capacitor values as for the first order three speaker network 2 Divide the capacitor values by 1 4 and multiply the inductor values by 1 4 to obtain the correct values for the second order three speaker network Fig 3 Circuit and design data for loudspeaker crossover networks Inductor and capacitor values for common speaker impedances and crossover frequencies are given in Table 3 Components with the same ref erence numbers have identical values i e L1 and L2 are two inductors of the same value C1 and C2 are capacitors of the same value Everyday Practical Electronics July 2002 CROSSOVER FREQUENCY With two speaker systems the cross over frequency is usually between 1kHz and 4 5kHz and the tweeter manufactur er s recommendations should be followed If the unit is of uncertai
243. period is fixed from the first moment that triggering occurred This can be irritating in this application since the lights will switch off even if your hand is still near the sensor Although they will be re triggered immediately this is not ideal especially since kitchen units are generally fitted with fluorescent lights which flicker as they switch on Hence resistor R1 and diode D3 were added so that every time Everyday Practical Electronics July 2002 OUTPUT DRIVER Little current is available from the out put of a CMOS gate and so transistor TR1 is employed to amplify the current avail able In fact Darlington transistors cost little more than normal ones and so a Darlington transistor was used in the pro totype The massive gain and power rating of a Darlington allows the use of almost any type of low voltage relay and allows the value of resistor R4 to be sufficiently high not to adversely affect the logic level at the output A relay with a 12V coil voltage should be employed for the output and its con tacts must be rated at 230V a c 5A or more Note that many relays on sale have contacts rated at 120V These are likely to burn out or fuse together in a short time It is much easier and safer to house the relay directly on the p c b and so check that the type obtained will fit There seem to be two slightly different pin spacings in common use and the p c b has been designed to accommodate either Diode
244. probably very familiar with the PIC16x84 which has 1K of pro gram memory in a single page All the tables used in the PIC Tutorial series Mar to May 98 for example are placed in the first 256 bytes of program memory in the x84 a constraint imposed for a reason that may not immediately be apparent In fact tables may be put anywhere in program memory space once the opera tion of the PCLATH function is under stood and the table is wholly contained within a sub page The number of bits Joe Becker described extended data required to access different spans of pro gram memory is shown in Table 1 The program counter PC value is held in a 13 bit special function register which can be regarded as having two parts PCH Program Counter High and PCL Program Counter Low for the high and low bytes respectively PCH resides in the upper five bits of the PC whereas PCL resides in the lower eight bits PCL can be written to directly as is done when normally accessing tables for example and the response to amending PCL takes immediate effect PCH though can only be written to via the lower five bits of special function register PCLATH Writing to PCLATH however only takes effect when the CALL GOTO or arithmetic operation involving PCL is performed It is worth noting that PCLATH is a write only buffer It is not safe to read PCLATH in order to perhaps do PC arith metic although Microchip s MPSIM sim ula
245. r all video monitoring security applications with direct connection to most colour cameras High quality with many features such as front concealed flap controls VCR correction button etc Good used condition fully tested uaranteed Dimensions W14 Y a234 zi 5 D Only 99 00 PHILIPS HCS31 Ultra compact 9 colour video monitor with ee dard composite 15 625 Khz video input via SCART socket Ideal for all monitoring security applications High quality ex equipment fully tested amp guaranteed possible minor screen burns In attrac tive square black plastic case measuring W10 x H10 x 13 D 240 V AC mains powered Only 79 00 D INDUSTRIAL COMPUTERS Tiny shoebox sized industrial 40 Mhz 386 PC system measuring only mm 266 w X 88 h X 272 d Ideal for dedicated control appli cations running DOS Linux or even Windows Steel case con tains 85 to 265 V AC 50 60 hz 70 Watt PSU a 3 slot ISA passive backplane and a Rocky 318 PC104 standard single board com puter with 8 MByte NON VOLATILE solid state Disk On Chip RAMDISK System comprises Rocky 318 PC 104 SBC ISA card with 40MHz ALi 386SX CPU 72 pin SIMM slot with 16 Mbyte SIMM AMI BIOS battery backed up real time clock 2 x 9 pin D 16550 serial ports EPP ECP printer port mini DIN keyboard con nector floppy port IDE port for hard drives up to 528 MByte capacity watchdog timer and PC 104 bus socket The 8 MByte solid state disk on a chip has its own BIOS
246. r maximum RF out put On off switch 6V operation Only 63x38mm 3028KT 12 95 AS3028 24 95 HARD WIRED BUG TWO STATION INTERCOM Each station has its own amplifier speaker and mic Can be set up as either a hard wired bug or two station intercom 10m x 2 core cable sup plied 9V operation 3021KT 15 95 kit form only TRVS TAPE RECORDER VOX SWITCH Used to automati cally operate a tape recorder not supplied via its REMOTE sock et when sounds are detected All conversations recorded Adjustable sensitivity amp turn off delay 115x19mm 3013KT 9 95 AS3013 21 95 700W power PCB 48mm x 65mm Box provided 6074KT 17 95 3 INPUT MONO MIXER Independent level con trol for each input and separate bass treble controls Input sensitivity 240mV 18V DC PCB 60mm x 185mm 1052KT 16 95 NEGATIVE POSITIVE ION GENERATOR Standard Cockcroft Walton multiplier circuit Mains voltage experience required 3057KT 10 95 LED DICE Classic intro to electronics amp circuit analysis 7 LED s simulate dice roll slow down amp land on a number at random 555 IC circuit 3003KT 9 95 STAIRWAY TO HEAVEN Tests hand eye co ordi nation Press switch when green segment of LED lights to climb the stairway miss amp start again Good intro to several basic circuits 3005KT 9 95 ROULETTE LED Ball spins round the wheel slows down amp drops into a slot 10 LED s Good intro
247. r monthly surgeons examine the fundamentals of bandgap references revisit Y class capacitors and a supply surprise Mind the Bandgap Regular EPE reader Gerard Galvin asks by email What does the term bandgap volt age mean I ve seen the term in data sheets and I think it relates to reference voltages First of all bandgap is a term relating to the physics of semiconductors and electri cal conduction in general In order for a material to be an electrical conductor the electrons must detach themselves from their atoms so that they can move around and form an electric current Attached electrons near the outside of the atom posses a certain range of ener gy values known as the valence band Unattached electrons which are free to move around and hence take part in con duction also have a range of possible ener gy values known as the conduction band Fig 1 Basic Vege voltage reference using a diode connected transistor supplied with a constant current Vee has a negative temperature coefficient It is not possible for an electron to have an energy value between the valence and conduction ranges The separation between these allowed energy ranges that is from the top of the valence range to the bottom of the conduction range is the bandgap For insulators the bandgap is very large so conduction does not take place For con ductors such as metals the valence and conduction bands overlap so elec
248. ransmitter case amp all components provided Receiver PCB 76x89mm 3072KT 52 95 PRODUCT FEATURE COMPUTER TEMPERATURE DATA LOGGER PC serial port controlled 4 channel temperature meter either deg C or F Requires no external power Allows continuous temperature data logging of up to four temperature sensors located 200m from motherboard PC Ideal use for old 386 486 comput ers Users can tailor input data stream to suit their purpose dump it to a spreadsheet or write your own BASIC programs using the INPUT command to grab the readings PCB just 38mm x 38mm Sensors con nect via four 3 pin headers 4 header cables supplied but only one DS18S20 sensor Kit software available free from our website ORDERING 3145KT 23 95 kit form AS3145 29 95 assembled Additional DS18S20 sensors 4 95 each SOUND EFFECTS GENERATOR Easy to build Create an almost infinite variety of interesting unusu al sound effects from birds chirping to sirens 9VDC PCB 54x85mm 1045KT 8 95 ROBOT VOICE EFFECT Make your voice sound similar to a robot or Darlek Great fun for discos school plays theatre productions radio stations amp playing jokes on your friends when answering the phone PCB 42x71mm 1131KT 8 95 AUDIO TO LIGHT MODULATOR Cortrols intensi ty of one or more lights in response to an audio input Safe modern opto coupler design Mains voltage experience required 3012KT 8 95 MUSIC BOX Activated by light Play
249. ray 3 oll code are used by some ADCs but we will only consider I Oot binary converters To 000 change the scaling of input voltage to output code Vppr can be changed within limits specified for the ADC To change the span of voltages converted shifting the converted range away from starting at 0 or to change the scaling beyond that controllable via Vppp requires external level shifting gain or attenuation circuitry e g using the shift and amplify circuits described in Teach In 2002 Parts 2 and 3 The binary output has n bits labelled Do through to D Do represents the units col umn of the binary number and is called the Least Significant Bit LSB D represents the two to the power n column of the bina ry number e g for eight bits this would be the 2 s or 128s column D is called the Most Significant Bit MSB The binary number output by the ADC changes by one that is by an LSB for an input voltage change of Vpp 2 This voltage is also referred to an LSB The dynamic range of the ADC indicates the difference between the largest and smallest output code and is given by the ratio of FSR to LSB and is equal to 2 Expressed in decibels it is approximately 6n dB Example dynamic range figures are given in Table 9 1 10 t O10 Table 9 1 ADC resolution Number of Number of Dynamic bits n Levels 2 Range dB 3 8 18 4 16 24 8 255 48 10 1024 60 12 4096 72 16 65536 96 20 1048576 120 In some
250. rd PC types CGA Hercules Super VGA etc Contains everything you need to know if you can t tell your EMS from your EGA Order code BP282 5 45 270 pages 13 99 128 pages Everyday Practical Electronics July 2002 Theory and Reference Bebop To The Boolean Boogie By Clive call me Max Maxfield Specially imported by EPE Excellent value An Unconventional Guide to Electronics Fundamentals Components and Processes This book gives the big picture of digital electronics This indepth highly readable up to the minute guide shows you how electronic devices work and how they re made You ll discover how transistors operate how printed circuit boards are fabricated and what the innards of memory ICs look like You ll also gain a working knowledge of Boolean Algebra and Karnaugh Maps and understand what Reed Muller logic is and how it s used And there s much MUCH more including a recipe for a truly great seafood gumbo Hundreds of carefully drawn illustrations clearly show the important points of each topic The authors tongue in cheek British humor makes it a delight to read but this is a REAL technical book extremely detailed and accurate A great reference for your own shelf and also an ideal gift for a friend or family member who wants to understand what it is you do all day 470 pgs large format Fie cel mexeye M H 26 95 BEBOP BYTES BACK and the Beboputer Computer
251. readers for damages although that might make others think before they copy In one case the reader has not been paid and in the other we are taking steps to recover the payment made REVIEW We are now in the process of reviewing the future of our JU page a pity but then as I have said so often the few spoil it for everyone I hope those responsible are suitably shamed you will find a special notice on our JU page this month I guess after 30 odd years on PE EE and EPE I should not be surprised but I am rather sad AVAILABILITY Copies of EPE are available on subscription anywhere in the world see below from all UK newsagents distributed by COMAG and from the following electronic component retailers Omni Electronics and Yebo Electronics S Africa EPE can also be pur chased from retail magazine outlets around the world An Internet on line version can be purchased and downloaded for just 9 99 US approx 7 70 per year available from www epemag com Everyday Practical Electronics July 2002 SUBSCRIPTIONS Subscriptions for delivery direct to any address in the UK 6 months 15 12 months 28 50 two years 52 Overseas 6 months 18 standard air service or 27 express airmail 12 months 34 50 standard air service or 52 express airmail 24 months 64 standard air service or 99 express airmail Online subscriptions for downloading the magazine via the Internet 9 99 US approx 7 70 for one year
252. rity of project builders prefer to do their own thing in this respect None of the designs requires the use of any test equip ment in order to get them set up properly Where any set ting up is required the procedures are very straightforward and they are described in detail Projects covered Simple MIIDI tester Message grabber Byte grabber THRU box MIDI auto switcher Auto manual switcher Manual switcher MIDI patchbay MIDI controlled switcher MIDI lead tester Program change pedal Improved program change pedal Basic mixer Stereo mixer Electronic swell pedal Metronome Analogue echo unit 01ko 1o10 H od Om k I 10 95 124 pages THE INVENTOR OF STEREO THE LIFE AND WORKS OF ALAN DOWER BLUMLEIN Robert Charles Alexander This book is the definitive study of the life and works of one of Britains most important inventors who due to a cruel set of circumstances has all but been overlooked by history Alan Dower Blumlein led an extraordinary life in which his inventive output rate easily surpassed that of Edison but whose early death during the darkest days of World War Two led to a shroud of secrecy which has covered his life and achievements ever since His 1931 Patent for a Binaural Recording System was so revolutionary that most of his contemporaries regard ed it as more than 20 years ahead of its time Even years after his death the full magnitude of its detail had not been fully utilized Among his 128 patent
253. riven designs In conventional frequency generating PIC software the following technique is typically used START FREQ clrf COUNTER movf COUNTER W movwf PORTB nop incf COUNTER F goto FREQ In this routine the value of COUNTER is repeatedly incremented and output to one of the ports Port B in this instance The rate at which Port B bit O oscillates would be the highest frequency available from this loop That at Port B bit 7 would be the slowest at eight octaves below that at bit 0 i e 256 times slower The actual frequency range would be controlled by the number of NOP instructions included in the loop In the fractional technique a binary word two bytes holds a constant 16 bit value which is repeatedly added to a 3 byte counter 23 bits within a loop It is the value of the most significant byte counter bits 16 to 23 which is output to the port This technique provides a far greater potential for tuning accuracy due to the ability to change the additive value by as little as 1 65536 TUNING ADJUSTMENT In the StyloPIC tuning values for all 25 notes are held in two blocks within the PIC s data Eeprom When the PIC has been Everyday Practical Electronics July 2002 newly programmed the two blocks are identical the second being regarded as holding the author s default values 1 e those which held true with the prototype unit There will be slight differences between clock rates of
254. rom all six issues PROJECT CODES All the available codes for the programmable projects in these issues including those for Price 12 45 each includes postage to anywhere in the world NaMe reret bee urs awed Sth sb 6 i aare iea iera HE bd Interface AdAESS ecese ideasi ea dew es hea be eas oo AEA ee l VOL 6 CONTENTS l BACK ISSUES July 2001 to December 2001 all the projects a a n n n nnn n nnn features news lUs etc from all six issues PROJECT CODES All the boven bbb bebe bebe eeeneay Post Code i available codes for the programmable projects in these issues including i l those for Interface C I enclose cheque P O bank draft to the value of 0 I EXTRA ARTICLES ON ALL VOLUMES i _ Please charge my Visa Mastercard Amex BASIC SOLDERING GUIDE Alan Winstanley s internationally l Diners Club Switch I acclaimed fully illustrated guide UNDERSTANDING PASSIVE COMPO Ie o L L L L L I NENTS Introduction to the basic principles of passive components l I HOW TO USE INTELLIGENT L C Ds By Julyan llett An utterly practi EEN e cock E E T E ese ceed eens a l cal guide to interfacing and programming intelligent liquid crystal display I modules PhyzzyB COMPUTERS BONUS ARTICLE 1 Signed and l Expiry Date Switch Issue No l Unsigned Binary Numbers By Clive Max Maxfield and Alvin Brown i END TO Ever Practical Electroni i PhyzzyB COMPUTERS BONUS ARTICLE 2
255. rrous amp non ferrous metals e Efficient quartz controlled microcontroller pulse generation Full kit with headphones amp all hardware KIT 847 PORTABLE ULTRASONIC PEsT SCARER A powerful 23kHz ultrasound generator in a compact hand held case MOSFET output drives a special sealed transducer with intense pulses via a special tuned transformer Sweeping frequency output is designed to give maximum output without any special setting up KIT B42 sisiasinciasasincesans 22 56 68000 DEVELOPMENT TRAINING KIT e NEW PCB DESIGN e 8MHz 68000 16 BIT BUS e MANUAL AND SOFTWARE e 2 SERIAL PORTS e PIT AND I O PORT OPTIONS e 12C PORT OPTIONS KIT 621 Pe 99 95 e ON BOARD 5V REGULATOR e PSU 6 99 e SERIAL LEAD 3 99 Stepping Motors MD38 Mini 48 step 8 65 MD35 Std 48 step 9 99 MD200 200 step 12 99 MD24 Large 200 step 22 95 MOSFET MkII VARIABLE BENCH POWER SUPPLY 0 25V 2 5A Based on our Mk1 design and preserving all the features but now with switchin pre regulator for much higher effi ciency Panel meters indicate Volts and Amps Fully variable down to zero Toroidal mains transformer Kit includes punched and printed case and all parts As featured in April 1994 EPE An essential piece of equipment 472 PIC PIPE DESCALER e SIMPLE TO BUILD e SWEPT e HIGH POWER OUTPUT FREQUENCY e AUDIO amp VISUAL MONITORING An affordable circuit which sweeps the incomin
256. s gle The front door is constructed of double walled steel with a designer style smoked acrylic front panel to enable status indicators to be seen through the panel yet remain unobtrusive Internally the rack features fully slotted rein forced vertical fixing members to take the heavi est of 19 rack equipment The two movable vertical fixing struts extras available are pre f punched for standard cage nuts A mains dis tribution panel internally mounted to the bottom rear provides 8 x IEC 3 pin Euro sockets and 1 x 13 amp 3 pin switched utility socket Overall ventila tion is provided by fully louvered back door and double skinned top section with top and side louvres The top panel may be removed for fitting of integral fans to the sub plate etc Other features include fitted castors and floor levelers prepunched utility panel at lower rear for cable connector access etc Supplied in excellent slightly used condition with keys Colour Royal blue some grey available CALL Can be supplied in many other configurations 33U 42U 47U Order as BC44 Order as DT20 Order as RV36 External dimensions External dimensions External dimensions mm 1625H x 635D x mm 2019H x 635D x mm 2019H x 635D x 603 W 64 H x 25 1603 W 79 5 H x 25 603 W 88 H x 25 D x 23 W D x 23 W D x 23 W Only Only Only Call for shipping quotation Undoubtedly a mira
257. s near the edge of the case as shown in the above photograph plus a hole for the mains neon LP1 The latter can fit any where providing it does not foul the p c b Check the position of the p c b before drilling You will also need a slot for the mains input and light output cables The printed circuit board may be housed by means of nylon self adhesive p c b sup ports Before removing the protective Ov E m ae ji ii F T mi my Lae Le Joo cover on these supports check that the sen sor and l e d s will fit into place The 1 e d s D1 and D2 should be neatly folded over the edge of the p c b as shown in the photo graph so that they fit into the holes You could have soldered the 1 e d s to the copper side of the board but exact align ment is much more difficult and it is hard to judge how long the leads should be to make a good fit The method suggested is much easier Having fixed the p c b the mains wiring can be completed but do not plug in until the base is fixed to the lid FINAL TESTING When the two halves of the case are screwed together connect the unit to a fused mains supply On switch on the relay should switch on with a click If pads P1 and P2 are still joined the timed period will be about 7 seconds Test the system to ensure that the trigger range is satisfactory Now disconnect from the mains supply and remove or cut the link between pads P1 and P2 The timed period will
258. s 8 Christmas songs and 5 other tunes 3104KT 7 95 20 SECOND VOICE RECORDER Uses non volatile memory no battery backup needed Record replay messages over amp over Playback as required to greet customers etc Volume control amp built in mic 6VDC PCB 50x73mm 3131KT 12 95 TRAIN SOUNDS 4 selectable sounds whistle blowing level crossing bell clickety clack amp 4 in sequence SGO1M 6 95 FACTOR PUBLICATIONS THE EXPERTS IN RARE amp UNUSUAL INFORMATION Full details of all X FACTOR PUBLICATIONS can be found in our catalogue N B Minimum order charge for reports and plans is 5 00 PLUS normal P amp P SUPER EAR LISTENING DEVICE Complete plans to build your own parabolic dish microphone Listen to distant voices and sounds through open windows and even walls Made from readily available parts R002 3 50 LOCKS How they work and how to pick them This fact filled report will teach you more about locks and the art of lock picking than many books we have seen at 4 times the price Packed with information and illustrations R008 3 50 RADIO amp TV JOKER PLANS We show you how to build three different circuits for disrupt ing TV picture and sound plus FM radio May upset your neighbours amp the authorities DISCRETION REQUIRED R017 3 50 INFINITY TRANSMITTER PLANS Complete plans for building the famous Infinity Transmitter Once installed on the target phone device acts like a room bu
259. s are not applied to the unit which could cause a safety hazard If you are plugging the unit into another item of equipment full consideration must be given to whether or not that equipment could potentially cause high voltages e g mains a c to be applied to the StyloPIC tracks DURABILITY With the prototype the stylus principal ly used is a round ended probe from a mul timeter Occasionally the rounded tip of a 3 5mm jack plug has been used Whatever your choice of stylus ensure that the con tact area is as smooth as possible to avoid damage to the p c b It is acknowledged that the long term durability of the p c b tracks will be signif icantly lower than that provided by the Component side of the StyloPIC It is turned the other way up to play the keyboard 492 COMPONENTS Resistors R1 R2 R4 R11 to R13 R15 10k 7 off R3 R6 R8 1k 3 off R5 R7 R9 R16 100k 4 off page R10 47k R14 22k R17 102 RM1 RM2 10k 8 common resistor module 2 off All 0 25W 5 carbon film except RM1 and RM2 See Potentiometer VR1 10k min preset round or rotary log see text Capacitors C1 C8 to C10 22u radial elect 16V 4 off C2 C3 C6 C11 100n ceramic 5mm pitch 4 off 10p ceramic 5mm pitch 2 off C7 10u radial elect 16V C12 2200u radial elect 25V C4 C5 Semiconductors D1 D2 1N4148 signal diode 2 off IC1 PIC16F877 20 microcontroller 20
260. s are the princi pal electronic circuits critical to the development of the world s first elecronic television system During his short working life Blumlein produced patent after patent breaking entirely new ground in electronic and audio engineering During the Second World War Alan Blumlein was deeply engaged in the very secret work of radar development and contributed enormously to the system eventually to become H25 blind bombing radar Tragically during an experi mental H2S flight in June 1942 the Halifax bomber in which Blumlein and several colleagues were flying crashed and all aboard were killed He was just days short of his thirty ninth birthday Order code NE32 15 99 420 pages VIDEO PROJECTS FOR THE ELECTRONICS CONSTRUCTOR R A Penfold Written by highly respected author R A Penfold this book contains a collection of electronic projects specially designed for video enthusiasts All the projects can be simply con structed and most are suitable for the newcomer to project construction as they are assembled on stripboard There are faders wipers and effects units which will add sparkle and originality to your video recordings an audio mixer and noise reducer to enhance your sound tracks and a basic computer control interface Also there s a useful selection on basic video production techniques to get you started Complete with explanations of how the circuit works shop ping lists of compone
261. s as well as worldwide web pages subject to restrictions see licence for full details Also contains a FREE 30 day evaluation of Paint Shop Pro 6 Paint Shop Pro image editing tips and on line help included Price 19 95 inc VAT Minimum system requirements for these CD ROMs Pentium PC CD ROM drive 32MB RAM 10MB hard disk space Windows 95 98 NT 2000 ME XP mouse sound card web browser Please send me CD ROM ORDER FORM L Electronic Projects _ Electronic Circuits amp Components V2 0 Analogue Electronics Digital Electronics V2 0 O Hobbyist Student Filters Institutional Electronics CAD Pack C Institutional 10 user Robotics amp Mechatronics L Site licence Assembler for PICmicro C for PICmicro Flowcode for PiCmicro Digital Works 3 0 Version required PiCmicro Development Board hardware Development Board UK plugtop power supply Development Board 25 way connecting lead Teach In 2000 FREE BOOK Electronic Components Photos Electronics In Control Single User Electronics In Control Multiple User Modular Circuit Design Single User Modular Circuit Design Multiple User OOOOOO OOO dododd SION AIUNC 4 5 4p a ake Rian eh Heeb one ene ae We Ges eed Ree eos aaa ene card NOs ae gaa eee Bee ees ck Here eek WR Bae Al a ee he eet ae te Switch Issue No n mi Chat ora Tea fl Note The software on each version is the same only the licence for use varies
262. s us to bring to you these GIANT 7 segment digital displays at a now affordable price The 10 character size gives exceptional read ability at long distances and enables a host of applica tions including score boards digital clocks coun E ters event timers etc As the units are a simple zP electromechanical device and operate from 12V DC simple switching via switches relays PIC or PC may be used to control single or multiple digits Units feature j integral Zero Power memory which greatly simplifies iii desgn For an excellent DIY practical article see the May issue of Everyday Practical Electronics magazine Ideal School College con struction project Supplied in good RFE condition complete with data sheet Less than 30 Only 29 95 or 4 99 00 0 of makers price Order RW44 Order PH26 i See pe THE AMAZING TELEBOX TV SOUND amp VIDEO TUNER CABLE COMPATIBLE k Oo r E Converts your colour monitor into a QUALITY COLOUR TV The TELEBOX is an attractive fully cased mains powered unit containing all electronics ready to plug into a host of video monitors or AV equipment which are fitted with a composite video or SCART input The composite video output will also plug directly into most video recorders allowing reception of TV channels not normally receivable on most television receivers TELE BOX MB Push button controls on the front panel allow reception of 8 fully tuneable off a
263. s we have published have turned out to have been copied from other magazines but this month two such items have come to light both have been published in our Ingenuity Unlimited column and both have been copied from other magazines This has happened even though both readers have signed a legal form to say I hereby confirm that the above mentioned submission for publi cation in the Ingenuity Unlimited column is my our own work and has not been published or currently submitted for publication elsewhere I have read and understand the Notice appear ing below The Notice referred to reads This is a legally binding agreement Breach of copy right is now a serious offence Material which is accepted for inclusion in Ingenuity Unlimited must not have been published or be currently submitted for publication elsewhere In signing this form you agree to indemnify us from any damages and costs arising as a consequence of any breach of copyrights held by any other parties So these EPE readers are apparently quite happy to commit a serious offence and to take all of us for a ride The items in question were previously published in Practical Wireless and Elektor maga zines and we apologise to them for breaching their copyright Fortunately the Editors of both magazines have been very understanding possibly because they too are well aware of the problems caused by a few unscrupulous readers so hopefully we will not need to go after these
264. se then might it be time to make the cheaper 16F627 8 the entry level PIC in EPE However I m well aware that the additional complexity of these PICs might put beginners off The 16F84 A is at least fairly simple Phil Cadman via email The differential is likely to continue and I have experimented with the F627 and found that at its simplest level it can readily be used in place of the F84 with a simple software modification if Port A is to be used as normal I O First add the equates CMCON EQU H 1F Then prior to the initialising commands for the ports etc make the statement within Page 0 MOVLW 7 MOV WF CMCON Port A will then behave in the normal way You must also ensure that all variables user regis ters start at H 20 or later not at H 0C as allowed by the C84 and F84 Toolkit TK3 software has been upgraded to handle F627 8 and is now on our web site as V1 3 A short article looking at basic F627 8 use and various mods made to TK3 to handle them will be published in the near future TK3 has also been modified to allow users to add their own specified PICs 14 bit command types to the list of those it handles TK3 AND PIC12C508 Dear EPE Here s a handy tip for readers who have built the Toolkit TK3 programmer board and want to program 12C508 or other 12 bit code PICs TK3 software only programs 14 bit code First go to www ic prog com and download the free programmer software and h
265. sensor The sensor consists of two separate devices the sensor itself and a compen sator which has the same characteristics as the sensor but its resistance doesn t change with the presence of gases The sensor and compensator are resistive and placed in two arms of a bridge circuit When a gas is present the sensor s D2 resistance changes and becomes unbalanced The complete circuit diagram of the Gas Sensor is shown in Fig 9 10 The bridge is powered from a 2 2V power supply derived from an LM317 variable voltage regulator IC1 The output voltage is set by preset potentiometer VR1 The sensor and com pensator are notated as X1 and X2 respec tively The other arms of the bridge are formed by 30Q resistors in our case 2 x 15Q and balanced by potentiometer VR2 Since the output of the bridge is a differ ence voltage we need to use a difference the bridge amplifier which is formed by C2 The gain is set to 21 but can be changed if the ratio between resistors R6 R7 and R8 R9 is changed You can also use an instrumen tation amplifier instead of IC2 to give a better CMRR It is advisable to construct and set the 2 2V supply before attaching it to the bridge as the sensor X1 may be damaged by higher voltages Once constructed monitor the voltage at point A and vary VRI until it reads 2 2V Build the rest of the circuit and connect the 2 2V supply Monitor the output and Everyday Practical Electronics Jul
266. so also does the potential at its source s Trigger pin 6 is now held high and fur ther trigger pulses are inhibited Diode D1 prevents any rapid discharge of C3 through output pin 5 D3 and TR4 With the value shown for C3 1uF further triggering is MAIN UMIT Cib FN 3 kam UMIT ICid FIN 11 tactile type which is provided so that an alarm sounder or beacon may be manually cancelled This takes IC1 s reset pins 4 and 10 low thus simultaneously resetting both monostable timer Cla and ICIb and instantly opening both relays RLA and RLB An alternative switch perhaps a keyswitch may be wired to the two solder pins on the p c b at either side of S1 and taken to a convenient location Resistor R6 and capacitor C4 are used to send a negative pulse of a few seconds to reset pins 4 and 10 at switch on This pre vents any spurious triggering at switch on on condition that the Alarm and Duress inputs are not left floating or discon nected To keep them from floating take these inputs high or low through 22kQ resistors be orientated so that each of its com moned sides is closest to the solder pins to either side of it Alternative 12V miniature relays may be used in place of those specified In this case their coil resistances should be 2502 or more so as not to overload transistors TR3 and TR4 As with the main p c b no case is spec ified since the unit could be mounted in various places as t
267. ss capacitors C6 C7 C8 and C9 should have a working voltage at least 1 5 times the transformer secondary voltage to protect them in the event of regulator failure 501 CONSTRUCTION l DU Ay IL OW PAU iP REGU LAA ED Any readers who have no experience of building or commis sioning mains powered equipment are reminded that the volt P wi ei o Ue PIL W ages involved can kill Anyone who feels unsure of his or her ability to complete a project of this kind MUST seek help and guidance from an experienced constructor The small components are assembled on the printed circuit board COM PON E N TS p c b as illustrated in Fig 2 together with a full size copper foil master and the interwiring to off board components This board is available from the EPE PCB Service code 356 POWER SUPPLY Commence construction by first soldering in position on the p c b Capacitors l See the rectifier diodes and non electrolytic capacitors This can be Ci to C4 100n ceramic 100V 4 off C5 2200u radial elect FOP see Table 1 C6 C8 100n ceramic 50V 2 off TALK C7 C9 470u radial elect 50V 2 off page Semiconductors D1 to D4 1N4002 rect diode for 1A max output 4 off 1N5401 rect diode for 3A max output 4 off P60D rect diode for 4A max output limited by regulators 4 off IC1 IC2 78 series for 1A 78S series for 2A maximum output See Table 1 2 off
268. ssembly Power handling and an extended low frequency response require a large strong and heavy cone and coil For good sensitivity the magnetic field cutting the voice coil must be intense Unfortunately this increases the imped ance at the cone s resonant frequency However this impedance rise can be con trolled by the speaker enclosure and a powerful magnet is always preferable The reproduction of low frequencies involves large cone excursions and the sus pension must be highly compliant High compliance also lowers the cone s resonant frequency and this extends the speaker s low frequency response However the need to maintain control of the position of the voice coil in the magnet gap imposes lim its on how free the suspension can be Cone movement for a given sound out put reduces with increasing speaker size but as we have seen greater diaphragm mass impairs transient and high frequency response HORSES FOR COURSES To avoid performance being excessively degraded by these conflicting require ments domestic hi fi systems usually combine two or more speakers each being designed to reproduce part of the audio fre quency spectrum The low frequency unit or bass speaker has a comparatively heavy cone and voice coil with a highly compliant suspension Clever designers have managed to obtain reasonable results with small speakers but an extended low frequency response and good power handling are more
269. st digit Temporarily connect the solder pin adjacent to D1 to each hole in Row B pins 13 to 24 until you find which of these lights l e d D1 You might need to give the dial a little play to find the exact position Now plug in the spare end of this first digit s wire into this hole The same procedure is now followed for the remaining eleven wires refer to Fig 1 When all twelve wires have been plugged in at both sides of the socket Row A to Row B test the lock by turning the dial to the correct 4 digit sequence in synchroni sation with the flashing of l e d D2 that is the dial must be pointing to each number at the moment that D2 flashes The solenoid should operate decisively when the correct code has been selected Turn to the Reset digit position that you have chosen to release the solenoid again If it does not release turn off the power and carefully re check the circuit Check again for warming in TR3 when the solenoid operates there should be virtually no per ceptible warming NS D A GF Using plastic covered wires to set up the lock s combination in the board mounted 24 pin d i l socket Note that a fairly precise turning of the switch dial is required This is not diffi cult but if you are a few degrees out of true when turning to a position on the dial this could reset the lock or send Alarm or Duress pulses to the Interface board WORKED EXAMPLES Suppose you are using a dial m
270. stor potentiometer can be connected across pads P1 and P2 A value of 1 megohm will provide a sufficient range of times COMPONENTS Resistors See R1 6802 R2 680k ROP R3 10k R4 4k7 TALK All 0 25W 5 carbon fim page Capacitors C1 C3 1000u radial elect 25V 2 off C2 100n disc ceramic Semiconductors D1 D2 infra red light emitting diode 2 off D3 D4 1N4001 1A 50V rect diode 2 off TR1 TIP122 npn Darlington transistor IC1 IS471F infra red sensor IC2 4001 quad 2 input NOR gate IC3 78L12 12V voltage regulator REC1 W005 1 5A 50V bridge rectifier Fig 2 Complete circuit diagram including mains power supply for the Infra Red Autoswitch The monostable is not stable in its new state since there is a voltage difference across resistor R2 Current therefore flows through R2 slowly charging up capacitor Cl So the voltage rises at C2c pin 8 and pin 9 and as it crosses the half way point gate IC2c changes state and completes the time period Now the change of logic level is fed back to IC2b pin 6 which causes IC2b out put pin 4 to switch back to positive This change of voltage is transferred across capacitor Cl so reinforcing the change already taking place All this happens very quickly so producing a clean change of state to OV at pin 10 of C2c Once the monostable is triggered fur ther triggering has no effect and the time
271. storage markets The unit offers read and write speeds of 750Mbytes per second in com parison to a DVD which offers a capacity of only 4 7Gbytes and speeds of 3Mbytes per second The market for the new product is expected to be huge with sales in excess of 25 billion by the year 2005 This shows the potential that can be realised when investors and academia come together Indeed Professor Stephen Elliott com mented This is an excellent example of Cambridge University and investors com ing together to turn academic research into a real business opportunity I m delighted to see Polight complete this round this company has a very exciting future in front of it For the future holographic data storage is highlighted by industry experts as offer ing the prospect of a revolution in data storage Until now commercialisation has not been possible for lack of a suitable media Now Polight has the challenge to resolve the last problems with its inorgan ic glasses that are given the name Holonide Michael Ledzion Polight s CEO com mented Holographic data storage is the next big step forward for the removable data storage industry It will now be very interesting to see how this new and exciting technology develops over the next few years and the impact it makes on the computer industry Everyday Practical Electronics July 2002 i INGENUITY UNLIMITED Our regular round up of readers
272. t Manufacturers and Suppliers The most comprehensive reference work ever produced at a price you can afford the CD ROM edition of THE MODERN ELECTRONICS MANUAL provides you with all the essential information you need THE MODERN ELECTRONICS MANUAL MEM CD ROM version only Revised CD ROM Edition of Basic Work Contains over 800 pages of information in Adobe Acrobat format Edited by John Becker Regular Supplements Additional CD ROMs each containing approximately 500 pages of additional information on specific areas of electronics will be available for 19 95 each Information on the availability and content of each Supplement CD ROM will be sent to you as they become available Presentation CD ROM suitable for any modern PC Requires Adobe Acrobat Reader which is included on the MEM CD ROM Price of the Basic Work 29 95 POST FREE ORDER BOTH MANUALS TOGETHER AND SAVE 10 A mass of well organised and clearly explained information is brought to you by expert editorial teams whose combined experience ensures the widest coverage Regular Supplements to these unique publications keep you abreast of the latest technology and techniques if required ELECTRONICS SERVICE MANUAL PRINTED VERSION ONLY EVERYTHING YOU NEED TO KNOW TO GET STARTED IN The essential work for REPAIRING AND SERVICING ELECTRONIC EQUIPMENT servicing and repairing SAFETY Be knowledgeable about Safety Regulations Electrical Safety and First Aid electr
273. t engineer for the British Standards Institute There are various different standards for complete equipment but they all require TWO levels of insulation between danger ous voltage and the operator The two lev els can be basic and earth or double or reinforced Note for the purposes of all standards both Live and Neutral sides of the mains are con sidered as dangerous for two reasons a the spikes referred to in the article which are with respect to earth and b there is the pos sibility of reversing the Live and Neutral as occurs with some continental wall plugs etc 520 Vrer VBetloutRe VpBeE tKAVBE VCONSTANT Fig 4 Concept circuit for bandgap reference Fig 5 Practical circuit of Fig 4 The Widlar Bandgap Reference or the two pin figure eight type of mains power cord used on some appliances Now to the crux of the matter a Y2 capac itor is only considered to be the equivalent of basic insulation Thus it is suitable for use between mains and a safety earth because the safety earth provides the second level of protection in the event of failure It is NOT suitable for use between mains and an unearthed ground or secondary circuit that may be touchable by the user Generally speaking it is safer to consider that any secondary circuitry or conductive parts will be touchable by the operator though there are plenty of exceptions in these days of plastics but in order to
274. t on Port B CLRF PCLATH Set for page 0 and sub page 0 LOOP1 BTFSS PORTA O Loop until button 0 GOTO LOOPI pressed LISTING 2 ORG 0000100001111111 087Fh hex page 1 LISTING 4 sub page 0 TABLE1 ADDWE PCL F LOOP2 BTFSS PORTA 1 GOTO LOOP2 Set up for page and sub page 0 Loop until button 1 pressed ORG 0000101101011001 OB59h page 1 sub page 3 TABLE2 ADDWE PCL F RETLW 00100100 RETLW 11010001 RETLW 01011100 RETLW 01110101 RETLW 10000110 RETLW 10100000 RETLW 00011001 RETLW 11000010 RETURN INSTRUCTION A CALL instruction pushes PCL and PCH values onto the stack A RETURN instruction pops those PCL and PCH val ues and puts them into the PC and no manipulation of PCLATH is required It might be necessary however to set PCLATH after the return as shown in the following example PROGRAM EXAMPLE This program example the software for which is available as stated later is designed for a PICI6F877 device plugged into the Toolkit Mk3 board Oct 01 with Port B connected to the l e d s and Port A bits O to 3 connected to the four push but ton switches It can equally well be simu lated through other equivalent hardware assemblies as a breadboard assembly for instance Throughout the example pro gram memory span is artificially extended by the use of ORG origin statements The uncommitted switch inputs are con nected to Port A bits 0 to 3 in active high mode Button X
275. t work with the PIC straight away The revised second edition covers the popular repro grammable EEPROM PICs P16C84 16F 84 as well as the P54 and P71 families Order code NE36 UNDERSTANDING PC SPECIFICATIONS R A Penfold Revised Edition If you require a microcomputer for business applica tions or a high quality home computer an IBM PC or compatible is often the obvious choice They are com petitively priced and are backed up by an enormous range of applications programs hardware add ons etc The main difficulty for the uninitiated is deciding on the specification that will best suit his or her needs PCs range from simple systems of limited capabilities up to complex systems that can happily run applications that would have been considered beyond the abilities of a microcomputer not so long ago It would be very easy to choose a PC system that is inadequate to run your applications efficiently or one which goes beyond your needs and consequently represents poor value for money This book explains PC specifications in detail and the subjects covered include the following Differences between types of PC XT AT 80386 etc Maths co processors Input devices keyboards mice and digitis ers Memory including both expanded EMS and extended RAM RAM disks and disk caches Floppy disk drive formats and compatibility Hard disk drives including interleave factors and access times Display adaptors including all standa
276. tarted to formulate plans for a television set with no moving parts while ploughing fields with a raster of furrows Farnsworth filed 482 his key patents USP 1 773 980 and 981 in 1927 Jenkins died in poverty in 1934 and although Baird lived until 1946 his mechanical system had long since been ousted in the UK by the all electronic technology developed by EMI and Marconi with a team including Alan Blumlein the inventor of stereo sound recording Baird had called on Farnsworth in 1934 to help him convert his mechanical system to an electronic one The deal collapsed because Baird s operation was shut down by a disastrous fire at his Crystal Palace research labs in South London in 1936 At the time Farnsworth was also working with German broadcasters on televising the Berlin Olympics And by then Philo Farnsworth and his small under funded company were in head on confrontation with David Sarnoff and RCA who were backing Vladimir Zworykin s approach Zworykin had told RCA in 1929 it would cost 10 000 and take two years to make electronic television work Sarnoff was later to complain it had taken ten years and cost 50 million Breaking Patents RCA s policy under Sarnoff was that RCA collected royalties and did not pay them So although Farnsworth s Image Dissector camera worked better than Zworykin s Iconoscope while Zworykin s Kinescope display worked better than Farnsworth s tube Sarnoff was not wi
277. tation is tuned in Capacitors C1 to C4 connected across the diodes suppress this interference which is known as modulation hum If radio tuners are to be powered from this circuit these capacitors must be fitted COMPONENT RATINGS Fuse It is good practice to protect the equip ment with an internal fuse of the lowest possible rating Because of the nature of the load this should be of the anti surge or slow blow type and a component rated at one amp 1A would be suitable for power supplies serving the amplifiers described in this series of articles Transformer The rectified d c voltage across the reservoir capacitor C5 must be at least 3V more than the regulator output when Everyday Practical Electronics July 2002 maximum current is being drawn from the supply Further the maximum input volt age to the regulator i c which is usually 35V for devices with a 2A rating must not MAINS TRANSFORME VOLTAGE SEE TABLE R PRIMARY TO SUIT SUPPLY FOR DETAILS OF SECONDARY be exceeded It is also desirable for the vi voltage drop across it to be no more than 10V or so or power dissipation within the chip will be increased and more elaborate heatsinking will be required These requirements can best be met if the mains transformer secondary voltage is 3V more than the regulated d c output To determine the required current rating of the secondary winding add together the demands of the amplifiers and
278. ters 10 sections Phase Shifting Networks 4 sections Active Filters 6 sections Oscillators 6 sections from Positive Feedback to Crystal Oscillators Systems 12 sections from Audio Pre Amplifiers to 8 Bit ADC plus a gallery showing representative p c b photos Complimentary output stage DIGITAL ELECTRONICS V2 0 Digital Electronics builds on the knowledge of logic gates covered in Electronic Circuits amp Components opposite and takes users through the subject of digital electronics up to the operation and architecture of microprocessors The virtual laboratories allow users to operate many circuits on screen Covers binary and hexadecimal numbering systems ASCII basic logic gates monostable action and circuits and bistables including JK and D type flip flops Multiple gate circuits equivalent logic functions and specialised logic functions Introduces sequential logic including clocks and clock circuitry counters binary coded decimal and shift registers A D and D A converters traffic light controllers memories and microprocessors architecture bus systems and their arithmetic logic units Sections on Boolean Logic and Venndiagrams displays and chip types have been expanded in Version 2 and new sections include shift registers digital fault finding programmable logic controllers and microcontrollers and microprocessors The Institutional versions now also include several types of assessment for supervis
279. tice anything out of the ordinary when the Duress position is selected The Duress signal may also be sent after the 4th digit has been selected e g on closing the lock again ONIJUNCTION OSCILLATOR The positive going pulses which are routed through the 12 way rotary switch SI are produced by a unijunction transistor u j t oscillator based on TR2 The u j t oscillator is chosen for its simplicity it uses just four components to flash lL e d D2 and provide a positive pulse at its base 1 b1 A u j t has a low off resistance called its inter base resistance or Rpg and this would cause this l e d to glow contin uously if it were wired to base 1 or base 2 For this reason it is wired to the emitter e which has a high emitter to base off resistance Current through the Le d is modest so a high brightness l e d would serve best in this position Do not change the value of resistor R3 A u j t is similar in its design to an n channel field effect transistor f e t but with some important differences Perhaps most importantly its n type material is only slightly doped which creates an avalanche effect when the emitter poten tial reaches the transistor s peak point in this case just over 8V causing the u j t to conduct simultaneously between its emitter and both bases When the u j t conducts the potential at base 1 rises sharply and a positive pulse is sent to tra
280. tle instrument of the century Courtesy www stylophone fsnet co uk 488 Brian was one of a team who in 1967 had founded a company providing dubbing and recording services to the broadcast and film industry from which services the company name Dubreq was derived Brian and his partners Bert and Ted Coleman recognised that this instrument had great potential if only it could be mar keted effectively with television being the obvious medium With this in mind the team also recog nised that the popularity of Rolf Harris made him the ideal celebrity to help pro mote their innovative instrument Bert demonstrated the Stylophone to Rolf who is said to have been very impressed This ultimately led to the instrument making its debut on Rolf s BBC TV Saturday Show in which a renowned sup port troupe of the era The Young Generation played along with Rolf on six additional Stylophones The Rolf Harris connection was to lead to the Stylophone becoming known as the greatest little instrument of the century EXPANSION Initially Stylophones were hand made and in pre decimal money sold at 8 18s 6d 8 92 modern which is estimated to be the equivalent of 95 in today s money Production soon expanded and a move was made from Dubreq s basement premises to a proper factory in Cricklewood London Staff numbers would eventually grow to around 75 during the company s full product
281. to CMOS decade counters amp Op Amps 3006KT 10 95 12V XENON TUBE FLASHER TRANSFORMER steps up a12V supply to flash a 25mm Xenon tube Adjustable flash rate 3163KT 13 95 LED FLASHER 1 5 ultra bright red LED s flash in 7 selectable patterns 3037MKT 5 95 LED FLASHER 2 Similar to above but flash in sequence or randomly Ideal for model railways 3052MKT 5 95 INTRODUCTION TO PIC PROGRAMMING Learn programming from scratch Programming hardware a P16F84 chip and a two part practical hands on tutorial series are provided 3081KT 21 95 SERIAL PIC PROGRAMMER for all 8 18 28 40 pin DIP serial programmed PICs Shareware soft ware supplied limited to programming 256 bytes registration costs 14 95 3096KT 12 95 ATMEL 89Cx051 PROGRAMMER Simple to use yet powerful programmer for the Atmel 89C1051 89C2051 amp 89C4051 uC s Programmer does NOT require special software other than a terminal emulator program built into Windows Can be used with ANY computer operating sys tem 3121KT 24 95 3V 1 5V TO 9V BATTERY CONVERTER Replace expensive 9V batteries with economic 1 5V batter ies IC based circuit steps up 1 or 2 AA batteries to give 9V 18mA 3035KT 5 95 STABILISED POWER SUPPLY 3 30V 2 5A Ideal for hobbyist amp professional laboratory Very reliable amp versatile design at an extremely reason able price Short circuit protection Variable DC voltages 3 30V Rated output 2 5 Amps Large
282. tor for loud speaker resonance checking design with David Barrington Infra Red Autoswitch As the Infra Red Autoswitch project is mains powered all the components have been specially selected to fit directly on the small printed circuit board p c b If alternative non board mounting components such as the mains transformer and relay are used you must take extra care when building and testing this unit In this case it is very important that the p c b and any off board parts be mounted in its case before testing and that a separate bat tery supply is used for checking its operation prior to mains connection The special Sharp 1S471F infra red sensor detector came from RS Components and carries the order code 564 396 They also supplied the p c b mounting short circuit proof mains transformer with twin 9V 0 027A 0 5VA total secondaries code 310 1263 These components can be ordered from any bona fide RS stockists including some of our advertisers You can order direct credit card only on amp 01536 444079 or on the web at rswww com A post and handling charge will be made The 12V d c low profile relay with 12A 250V a c rated single pole changeover contacts used in the model was purchased from Rapid Electronics 01206 751166 or www rapid electronics co uk code 60 4630 We understand that RS see above also stock a similar relay code 198 6933 The specified low profile case came from CPC credit card
283. tor lets you do this Table 2 shows starting addresses for pages and sub pages which are accessed under PCLATH control Table 2 Starting Addresses for Pages and Sub Pages Addresses are in hexadecimal Sub page Page 0 Page 1 Page 2 Page 3 0000 0800 1000 1800 0100 0900 1100 1900 0200 OA00 1200 1A00 0300 OBOO 1300 1B00 0400 OCOO 1400 1C00 0500 ODO0O0 1500 1D00 0600 OE00 1600 1E00 0700 OFOO 1700 1F00 NOOR WONDM O Table 1 Number of Program Counter Bits Required in Relation to PCLATH Number of bytes in Number of bits Number of bits program memory required in required in PCLATH program counter 2048 2K 11 0 4096 4K 12 1 8192 8K 13 2 Everyday Practical Electronics July 2002 SETTING PROGRAM COUNTER VALUE There are three ways in which the pro grammer can set a value into the program counter PC An instruction which carries out an arithmetic operation on the PC The most commonly used such instruction is adding a value to the PC from the work ing register when accessing a table such as ADDWEF PCL F as used in the example program listings A CALL or GOTO instruction which places the address of a label into the PC A RETURN instruction which places the contents of the stack top into the PC ARITHMETIC OPERATIONS Arithmetic operations on the PC involve the working register and other 8 bit wide registers It therefore follows that only PCL can be set with an arithmetic instruc tion PCH
284. trons can easily move between them and conduction readily takes place For semiconductors the bandgap is small so things get interest ing we can significantly change the elec trical properties by adding impurity atoms as we do with diodes and transistors Everyday Practical Electronics July 2002 Effects such as light dependent conduction are related to the bandgap too e g if a photon provides the correct amount of energy to an electron in a semiconductor valence band it can jump into the conduc tion band A full understanding of bandgaps and related issues requires some advanced physics and is therefore beyond the scope of this column We will therefore move on to look at bandgap reference circuits Fig 2 Two diode connected transistors of different physical sizes provide a voltage AVpe with a positive tempera ture coefficient Band of Circuits In circuits such as analogue to digital converters it is essential to have an accu rate and stable reference voltage if an accu rate and stable conversion is required We touch on this in Teach In 2002 Part 9 but we did not have space to go into reference circuits in detail A number of possibilities spring to mind when considering how we might design a voltage reference with the most obvious perhaps being to use the diode voltage drop or transistor base emitter voltage of a diode connected transistor see Fig 1 or a Zener diode These approaches are use
285. ues have been extracted following switch on or Reset Concert A 440Hz is triggered and will be heard from the loudspeaker or headphones as a hard attack slow decay audio output assuming you have turned up volume control VR1 Although the audio output decays the note itself continues to be generated at the pin 15 output of DAC IC2 This may be moni tored by a frequency counter at test point TP1 To establish its true accuracy use a frequency counter that shows the result to at least one decimal place The frequency 493 for true Concert A should be exactly 440 OHz Should you decide that a further adjust ment of the pitch is required repeat the Reset procedure as just described GENERATION GAME The software has been written so that all lines from the keyboard are constantly scanned to see if any is being touched by the stylus If one has a lookup table is used to determine which note frequency it refers to If the note is different to the previous one called that note s 2 byte tuning value is then copied from the NOTEVAL block and stored into registers FREQHI and FREQLO MSB and LSB respectively Simultaneously the envelope shaper is triggered via PIC output REO It is the FREQHI LO value that is added to the frequency generation counter pair WAVEHI and WAVELO in routine PLAY IT Each time the added value causes WAVEHI to rollover Carry flag set another counter OUTPUT is incremented It is the value of this c
286. unlimited access with a two hour cut off Tiscali s heavily advertised 10 0 package the great new service that gives you instant access to our key products is just a consolidation of some ISP portal offerings of dial up access web space mail text messaging and more Bundle ten services together add some lifestyle type TV advertising marketing and you get a trendy new account that in my case took a whole after noon to set up and suffered from incomprehensible error mes sages on the web site that needed several support calls at 50p minute to resolve This in turn cancelled out any likely sav ings for the first month In practice access is not always proving that reliable especially after dark but overall it is quite workable Remember that which ever ISP you dial up through you will usually be using their SMTP servers for your outgoing mail I was quite shocked to suffer lengthy delays several days due to a broken mail server which made com munications very garbled at times and made it more efficient to actually write a letter See you next month for more Net Work You can reach the author by email at alan epemag co uk anr at pet 1 3a EPE Tutorial Series TEACH IN 2002 Part Nine Analogue to Digital Conversion sampling and Nuclear Radiation Sensing IAN BELL AND DAVE CHESMORE Making Sense of the Real World Electronics to Measure the Environment GOING DIGITAL HE main a
287. ur correctly in other words the sub page is immaterial for this particular operation as in Fig 2 But for the second and third lines of Listing 6 where preparations are made to access the table at TABLE4 setting sub page 2 is material and this is done simply be setting bit 1 of PCLATH The first line in the table is then accessed and a value of 10010111 is returned for display on Port B Pressing button 3 exits from the loop to the final Everyday Practical Electronics July 2002 LISTING 5 LISTING 6 MOVLW 00000101 Set up for page 0 ORG O0001101010011100 LA9Ch page 3 MOVWE PCLATH sub page 5 sub page 2 MOVLW 3 Get fourth line from JUMP1 MOVLW 0 For first line of table CALL TABLE3 third table BSF PCLATH 1 Set up for sub page 2 MOVWE PORTB Display it on port B CALL TABLE4 fourth table LOOP3 BTFSS PORTA 2 Loop until button 2 MOVWE PORTB Display it on Port B GOTO LOOP3 pressed LOOP4 BTFSS PORTA 3 Loop until button 3 MOVLW 00011000 Set up for page 3 GOTO LOOP4 pressed MOVWE PCLATH sub page 0 FINAL MOVLW FF GOTO JUMPI1 Go there MOV WE PORTB GOTO FINAL ORG 0000010101100100 0564h page 0 TABLE4 ADDWE PCL F sub page 5 RETLW 10010111 TABLE3 ADDWE PCL F RETLW 00111111 RETLW 00110111 RETLW 01101011 RETLW 11001101 RETLW 10101010 RETLW 11100001 RETLW 01100110 and infinite loop whereby 11111111 is shown on Port B PROGRAMMER S TASK Every CALL and GOTO and every arithmetic
288. ur just 39 95 Ref 15P42SP NEW UNIVERSAL SOLAR CHARGER Charges AAAs AAs Cs and D type NiCads 9 99 Ref UNISOL 12V SOLAR POWER WATER PUMP Perfect for many 12V d c uses from solar fountains to hydroponics Small and compact yet powerful works direct from our 10W solar panel in bright sun Max HD 17ft max flow 8 Lpm 1 5A Ref AC88 18 99 SOLAR MOTORS Tiny motors which run quite happily on voltages from 3V 12V d c Works on our 6V amorphous Gin panels and you can run them from the sun 32mm dia 20mm thick 1 50 each MAMOD STEAM ENGINES and a full range of spare parts Check out www mamodspares co uk SUPER WIDEBAND RADAR DETECTOR Whistler 1630 Detects both radar and laser X K and KA bands speed cameras and all known speed detection systems 360 degree coverage front and rear waveguides 1 1in x 2 7in x 4 6in fits on visor or dash new low price 99 Ref WH1630 Other models available at www radargun co uk BUG DETECTORS A new detector at a sensible price Detects bugs hidden in rooms computers etc between 1 200MHZz adjustable sensitivity 9V PP3 battery required 29 95 Ref BDET2 GIANT WEATHER BALLOONS made by Totex we blew one up to 7ft diameter then it popped due to stones on the ground 13 99 Ref TOTEX PHILIPS VP406 LASER DISC PLAYERS sale price just 9 95 Scart output just put your video disk in and press play standard audio and video outputs 9 95 Ref VP406 12V DC SIRENS Very
289. us the Teach In interactive software covering all aspects of the series We have also added Alan Winstanley s highly acclaimed Basic Soldering Guide which is fully illustrated and which also includes Desoldering The Teach In series covers Colour Codes and Resistors Capacitors Potentiometers Sensor Resistors Ohm s Law Diodes and L E D s Waveforms Frequency and Time Logic Gates Binary and Hex Logic Op amps Comparators Mixers Audio and Sensor Amplifiers Transistors Transformers and Rectifiers Voltage Regulation Integration Differentiation 7 segment Displays L C D s Digital to Analogue Each part has an associated practical section and the series includes a simple PC interface so you can use your PC as a basic oscilloscope with the various circuits A hands on approach to electronics with numerous breadboard circuits to try out Sine wave relationship values 12 45 including VAT and postage Requires Adobe Acrobat available free from the Internet www adobe com acrobat FREE WITH EACH TEACH IN CD ROM Electronics Hobbyist Compendium 80 page book by Robert Penfold Covers Tools For The Job Component Testing Oscilloscope Basics ELECTRONICS IN CONTROL Two colourful animated courses for students on one CD ROM These cover Key Stage 3 and GCSE syllabuses Key Stage 3 A pictorial look at the Electronics section featuring animations and video clips Provides an ideal introduction or revision guide includin
290. version Fuse protected input circuitry Order Code Power Voltage Price aco 651 581 150W Continuous 12V 36 39 651 578 150W Continuous 24V 36 39 651 582 300W Continuous 12V 50 64 651 585 300W Continuous 24V 50 64 651 583 600W Continuous 12V 101 59 651 593 600W Continuous 24V 101 59 651 587 1000W Continuous 12V 177 18 651 597 1000W Continuous 24V 177 18 651 602 1500W Continuous 12V 314 52 651 605 1500W Continuous 24V 314 52 651 589 2500W Continuous 12V 490 54 651 599 2500W Continuous 24V 490 54 LUST OWN 1S 651 583 600W VERSION Many uses include Fetes Fairgrounds Airshows Picnics ae RLY A Rei ES a cee Camping Caravans Boats Carnivals Field Research and Amateur ETC PRICES ARE INCLUSIVE OF V A T SALES COUNTER VISA Radio field days Powering Desktop amp Notepad Computers AND ACCESS ACCEPTED BY POST PHONE OR FAX OR EMAIL cosas US AT SALES BKELEC COM ALTERNATIVELY SEND CHEQUE OR POSTAL ORDERS MADE PAYABLE TO BK ELECTRONICS MasterCard VISA EJ B K E LECTRONICS cera For Full Specifications View our web site at TEL 44 0 1702 527572 FAX 44 0 1702 420243 Pid A A AR AA se 20 discount for EPE readers digimess power supplies from 99 00 inc vat amp del vb Vann Draper Electronics Ltd The test amp measurement specialists www vanndraper co uk Test equipment from Grundig digimess Kenwood Hameg Tektronix Avo and more Use this coupon for your order
291. verter When an object is detected pin 2 of IC1 switches to OV and this causes output pin 3 of IC2a to switch to positive high This signal is fed to input pin 5 of IC2b so trig gering the monostable formed by C2b and IC2c When triggered pin 4 of IC2b switches to OV and this sudden change of voltage is transferred to the other side of capacitor C1 so reducing the voltage at pin 8 and pin 9 to OV Hence output pin 10 of IC2c switches to positive and this is fed back to input pin 6 of IC2b so latching the mono stable into its new state R1 D3 6809 1N4001 k a output pin 2 of ICI switches to OV object detected capacitor Cl is discharged With this addition timing is from the last time that an object was detected So if you stand near the sensor the lights will remain on Diode D3 prevents current flowing towards capacitor Cl when IC1 pin 2 is positive and resistor R1 is needed to reduce the surge of current that might damage IC1 When the circuit is being tested a time period of more than five minutes can be tedious So resistor R3 was included together with solder pads P1 and P2 Terminal pins or a wire link may be sol dered to these pads so that at the testing stage the time period can be reduced to just a few seconds When the system is work ing the link can be cut so reverting to the full time period If you wish to have a variable time peri od then resistor R2 may be omitted and a variable resi
292. vince of the program author s although there are guide lines For exam ple this author s policy is a Where something seems to be over whelmingly complex break it down into chunks of manageable size b Try and write separate routines termi nated in a RETURN for each of the chunks and aim to keep routine size to a page or less avoid what is called spaghetti code which goes on and on without a break c Make a routine self contained with as few links to other routines as possible Do not use GOTO instructions between rou tines but remember the PIC s stack only allows a limited number of nested calls d All variables general purpose regis ters in the PIC language are global that is visible to all routines Be careful to reduce the number of routines which alter variable values to as small a number as possible preferably one only perhaps by defining more variables than is strictly nec essary Be especially cautious where vari able values are altered in interrupt routines Read Malcolm Wiles articles on Using PIC Interrupts Mar Apr 02 carefully e Insert comments at the head of each routine which describe what the routine does what routine s it calls and where it is called from f Nearly every line or group of lines in the code deserves its own comment even if trivial Define what each variable does When mystified by some lines of code or things seem to be ambiguous a seemin
293. width expansion can be such that it is not always possible to use digital transmis sion We will illustrate this later when we have introduced the concepts needed SMART AND INTELLIGENT SENSORS Up to now we have been looking at sen sors separately from associated circuitry such as linearising and amplifying circuits Advances in technology particularly in integrated circuit fabrication provide us with the ability to include most if not all signal conditioning circuitry on the same piece of silicon as the sensor Such devices are called integrated sensors and we have already used some of these TSL250 pho todiode and integrated amplifier and LM35 temperature sensor are two examples We can go further and add a microcon troller creating a so called smart sensor This allows much more functionality including data logging storing values in memory at intervals digital signal processing such as filter ing calculating averages maximum and minimum values transforming data into meaningful units e g voltage from a temperature sensor into degrees Celsius transmitting data e g RS 232 or format ting data for a printer display etc All this requires us to convert voltages currents etc into a digital form i e using an A to D converter We can go one stage further and add intelligence to create intelligent sensors By intelligence we mean artificial intelligence such as expert systems or artificial neur
294. x 20mm and have a threaded hole 5 16th UNF in the cen tre and a magnetic strength of 2 2 gauss We have tested these on a steel beam running through the offices and found that they will take more than 170lb 77kg in weight before being pulled off Supplied with keeper 19 95 ea Ref MAG77 HYDROGEN FUEL CELL PLANS Loads of information on hydro gen storage and production Practical plans to build hydrogen fuel cell good workshop facilities required 8 set Ref FCP1 STIRLING ENGINE PLANS Interesting information pack covering all aspects of Stirling engines pictures of home made engines made from an aerosol can running on a candle 12 STIR2 12V OPERATED SMOKE BOMBS Type 3 is a 12V trigger and 3 smoke cannisters each cannister will fill a room in a very short space of time 14 99 Ref SB3 Type 2 is 20 smaller cannisters suitable for mock equipment fires etc and 1 trigger module for 29 Ref SB2 Type 1 is a 12V trigger and 20 large cannisters 49 Ref SB1 BRAND NEW NATO ISSUE RADIATION DETECTORS SALE PRICE JUST 69 95 Current NATO issue standard emergency services unit Used by most of the world s military personnel New and boxed Normal retail price 400 Bull s bargain price just 69 95 Ref PDRM BASIC GUIDE TO BIO DIESEL How to make diesel fuel from used kitchen oil 6 Ref BIOF SAVE s RCB UNITS Inline IEC lead with fitted RC break er Installed in seconds Fit to any computer monitor office
295. xample if Vi 18 OV and the voltage at Vef is 2 0V then the 00000000 is equivalent to 0 OV and 11111111 equivalent to 4 0V In our demonstration circuit the reference voltage is set at half the supply by potential divider R2 and R3 this makes 11111111 equal to 5V Chip select CS is set low to permanently enable the device and Read RD set low to enable the outputs DO to D7 Control of the ADC is via the Write input WR which is active low and is derived from a low frequency squarewave oscillator IC1 operating at about 200Hz The internal operation of the ADC is controlled by an internal high speed oscil lator operating at a frequency set by resis tor R4 and capacitor C3 This means that each conversion takes place over about 100ms but at 200 samples per second The input voltage to be converted to dig ital output is provided by VR1 and the bina ry output is displayed on l e d s D1 to D8 which are buffered by resistors R5 to R12 An Le d array was used in the test model but individual l e d s can be used instead Construct the circuit in Fig 9 12 and vary potentiometer VR1 You should see the 1 e d s changing in a binary manner The accompa nying photograph shows a binary value of 01011111 which is equal to 95 in decimal least significant bit is at the top of the array Using the signal generator from Part 8 you could input a low frequency sinewave and watch the binary values changing You can also vary the valu
296. y indexes are published in the December issue for that year Where we are unable to provide a back issue a photocopy of any one article or one part of a series can be purchased for the same price Issues from Jan 2002 onwards are also available to download from www epemag com MAR 01 PROJECTS e Doorbell Extender Body Detector e DIY Tesla Lightning Circuit Tester FEATURES e Understanding Inductors The Schmitt Trigger Part 5 Circuit Surgery Interface New Technology Update Net Work The Internet Page APRIL 01 PROJECTS Wave Sound Effect Intruder Alarm Control Panel Part 1 Sound Trigger EPE Snug Bug Pet Heating Control Centre FEATURES e The Schmitt Trigger Part 6 e Practically Speaking Ingenuity Unlimited Circuit Surgery Net Work The Internet Page e FREE supplement An End To All Disease a CST Ll e et nt UN a Photostats onl PROJECTS e Camcorder Mixer PIC Graphics L C D Scope D C Motor Controller Intruder Alarm Control Panel Part 2 FEATURES e The Schmitt Trigger Part 7 Interface Circuit Surgery Ingenuity Unlimited New Technology Update Net Work The Internet Page JUNE 01 PROJECTS e Hosepipe Controller In Circuit Ohmmeter Dummy PIR Detector e Magfield Monitor FEATURES e Controlling Jodrell Bank PIC1687x Extended Memory Use e Practically Speaking Ingenuity Unlimited New Technology Update Circuit Surg
297. y 2002 COMPONENTS Lab 9 1 See oo ae S a D R2 to R5 15Q aot TALK R6 R7 5k6 2 off Page R8 R9 120k 2 off All 0 25W 5 carbon film Potentiometers VR1 4k7 sub min preset VR2 470Q sub min preset Semiconductors IC1 LM317 variable voltage regulator 1 5A IC2 OP177 op amp X1 X2 NAP 7AU gas sensor compensator pair Miscellaneous Stripboard section see photo Lab 9 2 Resistors R1 120k Fig 9 10 Gas Sensor circuit diagram 2k2 2 off 12k R5 to R12 470 8 off All 0 25W 5 carbon film Potentiometer VR1 10k rotary carbon lin Capacitors C1 10u tantalum 16V C2 100n polyester C3 150p ceramic polystyrene Semiconductors D1 to D8 red e d 8 off see text IC1 4093 quad 2 input NAND Schmitt trigger IC2 ADC0804 8 bit ADC The sensor circuit in Fig 9 10 is assembled on stripboard Baa eke Lab 9 5 6k8 15k 27k 2 off 470k All 0 25W 5 carbon film Resistors Capacitors C1 82p ceramic polystyrene C2 100p ceramic polystyrene C3 C5 10n polyester 2 off C4 10u tantalum 16V i im L Semiconductors TERS ba B b i 1 e a i eee aes m E IC1 4093 quad 2 input ae Sars on eae NAND Schmitt trigger The stripboard is then connected to the op amp on the breadboard IC2 LTC1062 5th order switched capacitor low pass filter N B Some components are repeated between Lab Works Approx Cost 26 Guidance Only excl hardware
298. y of possible uses For instance it could be used to autho rise the use of another switch for a prede termined period It could also be used to disable another switch for a predetermined period or be used as a form of double handed switch The logic required to do this is simple and the author leaves the details to the ingenuity of the constructor In short one set of relay contacts is wired in series with the opposite monostable timer s input so making one input dependent on the state of the opposite relay Remember to use 22kQ pull up or pull down resistors where necessary so that no inputs are left floating TIME OUT Finally the Alarm input may be used as a timer This begins to time the instant that a pushbutton is pressed and will receive no further trigger inputs until the timing peri od has ended It may be instantly reset at any time by means of switch S1 For this purpose the value of capacitor C3 may be reduced to InF so that the pushbutton is disabled only for two or three seconds after the timing period has ended A 22kQ pull up resistor is wired between the input and the positive rail and a momentary action pushbutton is wired between the Alarm input and OV The instant the pushbutton is pressed the timing period begins The output is taken from relay RLA Everyday Practical Electronics July 2002 Regular Clinic CIRCUIT ALAN WINSTANLEY and IAN BELL Ou
299. your own working robot or android using both off the shelf and workshop constructed materials and devices Computer control gives these robots and androids two types of artificial intelligence an expert sys tem and a neural network A lifelike android hand can be built and programmed to function doing repetitive tasks A fully animated robot or android can also be built and pro grammed to perform a wide variety of functions The contents include an Overview of State of the Art Robots Robotic Locomotion Motors and Power Controllers All Types of Sensors Tilt Bump Road and Wall Detection Light Speech and Sound Recognition Robotic Intelligence Expert Type Using a Single Board Computer Programmed in BASIC Robotic Intelligence Neutral Type Using Simple Neural Networks Insect Intelligence Making a Lifelike Android Hand A Computer Controlled Robotic Insect Programmed in BASIC Telepresence Robots With Actual Arcade and Virtual Reality Applications A Computer Controlled Robotic Arm Animated Robots and Androids Real World Robotic Applications Order code MGH1 14 99 224 pages 19 99 536 DIRECT BOOK SERVICE NOTE ALL PRICES INCLUDE UK POSTAGE The books listed have been selected by Everyday Practical Electronics editorial staff as being of special interest to everyone involved in elec tronics and computing They are supplied by mail order to your door Full ordering details are given on the last book page For

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