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EPE Online Magazine- August 2007 Vol. 26, No. 7

1. Li LI n n I oh gt SA HHH LI I l copper underneath then run the free end across the top ofall four pots see Fig 6 and photos It s then soldered to the metal body of each pot to make sure that all four and also the metal front panel when it s fitted are con nected to the amplifier s signal earth Note that you will need to scrape away a small area of the anodising on each pot body using sandpaper to ensure that the solder properly bonds to the metal Therotary selector switchisfitted next but this also needs its spindle cut short In this case cut the spindle at a point just 6mm from the threaded bush and again remove any burrs using a small file 0 Fig 4 THD noise vs output power into 4Q The right channel red has higher distortion at the lower power levels due to noise from the power supply circuitry There s another operation to be performed on the switch before it s mounted This is to make sure that it is set for only three positions This is done by first unscrewing the mounting nut and removing the star lockwasher underneath That done prise up the switch s stop washer and turn the switch spindle anticlockwise with your fingers until it won t turn any further After
2. INTO RE8 SCK1 RF6 INT2 RD1 INT1 RDO RD3 Vss Migrating to DSC This article concentrates on migrating our motor control design onto a 16 bit dsPIC Digital Signal Controller DSC Rather than supplying the entire source code we will just show code fragments but the whole source can be downloaded from the EPE website at www epemag wim borne co uk By migrating from the 8 bit PIC to a 16 bit PIC many of the peripherals will be familiar and we can still use the same MPLAB development environment and Table 1 Board connections BACK EMF Fig 1 Changes to the Mechatronics board ICD2 debugger that we used previously Additionally M icrochip s free C30 Student Edition C compiler and libraries can be dsPIC30F 4011 PIN 42 ANO AN3 Vss U2TX RF5 PGC EMUC UIRX PGD EMUD UITX AV dd AVSS PWMIL REO PWMIH RE1 From JAROT J16 BACK EMF J13 Vss J10 RD4 JIORC RX LO Coll x Direct from bent PIN Direct from bent PIN JIO RB5 COM1 J 10 RB4 COMO To J 13 RAO ANO J 13 RA3 AN3 J13 RD1 JP2TX J10 RB6 ICSPCLK J10 RB7 ICSP DAT J 10 Vdd J 10 Vss JI N2 al eal Cut trace from J 10 RC6 TX to
3. D1 5V REG1 CON 1N4004 109 7805 pee L 1 5W Rre NI ve ip 2DI A A Aiha ai 16V FL 1924F 100uF 100nF EE 100nF w N CON2 9 14 5V DC mals INPUT gi T T rO ARMED RANGE ie D2 i i 5 IN4004 au O ALARM CI a AT9052313 bo l D l l 1N4004 ko Lo DOOR n 1 STRIKE 5V Lo TAMPER n i SWITCH 5V IC3 10k MC34064P 5 NOTE X NOT CONNECTED RFID SECURITY MODULE Fig 1 a hybrid RFID reader module IC2 from ID Innovations contains all the tag reading electronics Tag validation and alarm functions are handled by an Atmel AT90S2313 microcontroller IC1 Alarm connections Before examining the operation of the module in some detail let s take a closer look at two open collector out puts and the digital input mentioned earlier We ve labelled the first output armed It is intended for connection to the main control unit to control system arming and disarming The polarity of this output is jumper se lectable to match the control unit s input requirements see Table 2 Everyday Practical Electronics August 2007 Note not all commercial alarm systems provide an arm disarm input as necessary for use with this system Consult your alarm system s manual to determine its suitability Alternatively this output can be used to control an engine immobiliser circuit for older vehicles that do not already have such a device The second output
4. MonCon MonCon is a product range intended to form the intelligence at the heart of any equipment from bench top scientific instruments production equipment ATE etc up to large process control systems The MonCon range takes a new approach to monitoring and control by using modules that encapsulate a complete task such as the stepper motor controller module that includes all inputs and outputs necessary to form a complete stepper motor controller driver including encoder feedback The general purpose modules such as the Analogue input board are designed to be customized at minimum cost We can supply such modules to your requirements at little or no additional cost The MonCon range is based on a collection of modules each performing specific and well defined tasks All modules plug into a back plane which provides power distribution intercommunication and incorporates the necessary connectors linking the MonCon system to the rest of the equipment The modules and backplane connectors have been designed to simplify the interconnection requirements within your equipment Most devices such as stepper motors sensors etc are wired to the MonCon backplane directly with no splices or links so the wiring loom is simplified cheaper to manufacture and more reliable We understand that many manufacturers would want to have full control over critical parts of their products so we are happy to allow our cust
5. Fig 7 Adding a pole The added capac itor and output impedence of the previ ous stage produce a pole in the cur cuit s response Fig 9 Block diagram of an op amp showing compensation capacitor WWW DEN ag Cor Fig 8 Miller effect capacitor The response is to the circuit in Fig 7 with the capacitance reduced by approxi mately the gain of the amplifier point and will be safely below 1 once the contri bution of the pre exist ing high frequency poles push the phase shift to 1802 This low frequency pole domi nates the frequency response so this approach is called dom inant pole compensa tion The frequency response of the op amp with the dominant pole compensation is shown in Fig 6 Note there is now a healthy phase margin and circuits built with this op amp using negative feedback would be stable Fig 6 The response of the circuit from Fig 5 with dominant pole compansation added This circuit would be stable with negative feedback In Practice We have seen that adding a dominant pole makes our op amp stable but how do we do this in practice Recall that the cir cuit in Fig l has a single pole so adding an RC circuit like this between two stages of the amplifier would do the trick We do not need the resistor as the output impedance of the previous stage will suffice This is illustrated in Fig 7 Unfortunately the circuit in Fig 7 would require a very large capacitor
6. PCB Production prann Materials A4 Artwork Film per 10 sheets Clear Manual Film 1 20 Clear Laser Film EI White HQ Laser Film 4 62 Etch Resist Pens Dalo Pen 3 36 Stgedtler Fine Pen 0 96 Etch Resist Transfers z Seno mixed DIL pads 2 24 Seno mixed Rnd pads 2 24 Alfac mixed pads aran Transfer Spatular Panariti We carry the full range of Seno amp Alfac PCB transfers see our catalogue for full details Soldering Irons We carry In stock a wide range of soldering iron and soldering accessories Irons from 12 to 100 Watts 20W 240V Basic 14 25W 240V Ceramic 7 14 30W 240V Basic 4 68 Desolder Pumps Basic 165 x 18mmB 2 85 Antistatic 195mm 3 92 Antex Mini 198mm 6 02 Antex Pro 210mm 10 26 so denna Station A 48W adjustable temperature soldering station with a rotary di al LED Temperature metering on off switch iron holder and tip clean ing sponge This station features ac curate heat ee for instant compensation amp stable tempera tures Adjustable temperature range of 150 420 C Low volt age iron with Silicone cable Supply 240V Iron 24V 48W Model 167 540 41 66 Soldering Station A 48W adjustable temperature soldering station with a rotary di al Paa tempr are Indication on off switch iron holder and tip cleaning sponge This station fea tures accurate heat sensing for instant compensation amp stable temperatures Adjustable tem pat ra
7. e pi yo ca t Water Level Indicator Kit This simple circuit illuminates a string of LEDs to quickly indicate the water level in a rainwater tank The more LEDs that illuminate the higher the water level is inside the tank The input signal is provided by ten sensors located in the water tank and connected to the indicator unit via light duty figure 8 cable Kit supplied with PCB with overlay machined case with screenprinted lid and all electronic components e Requires 8mm OD PVC hose pipe length required depending on depth of tank Requires 9 12VDC or AC wall adaptor Maplin JC91Y 14 99 Speedo Corrector Kit When you modify your gearbox diff ratio or change to a large circumference tyre it may result in an inaccurate speedometer This kit alters the speedometer signal up or down from 0 to 99 of the original signal With this improved model the input setup selection can be automatically selected and it also features an LED indicator to show when the input signal is being received Kit supplied with PCB with overlay and all electronic components with clear English instructions s ki L VIW Improve d Mode fi k or hoa a Universal Speaker Protection and Muting Module Kit The primary function of this versatile project is to L protect your expensive speakers against damage in the event of catastrophic amplifier failure such as a shorted output tr
8. see Fig 7 Make sure that you have a layer of epoxy adhesive between the two surfaces as well as a fillet all around the lower circumference of the knob The assembly should then be left untouched for 24 hours so that the adhesive can cure Once it has cured attach the side actuator knob to the rotary switch by pushing it down onto the spin dle as far as it will go Check that 55 The small rectangular slot in the front panel for the input selector switch paddle is best cut by drilling a row of 2 5mm holes fairly close to gether and then opening them into the slot using jeweller s needle files The larger round holes for the input sockets and the control pot spindles are best made by first drilling a small hole in the centre of each position It s then simply a matter of opening each hole out to the correct diameter using a hand held tapered reamer Finally remove any burrs from the holes using a countersink bit Once both panels have been pre pared you can prepare dress labels by photocopying the artworks onto adhesive backed A4 label paper The stickers can then be given a protective coating using wide clear cellulose packaging tape before cutting them to size After that you just peel of the backing carefully affix each one to its How To Make The Switeh Actuator KNOB ALIGNED WITH SLUG HOLE AT 12 O CLOCK CUT 5 5mm FROM TOP OF KNOB SE A i EPOXY CEMENT 30 N PE KNOB CUTTING PADDLE ALIGNED
9. NEW USB All Flash PIC ee USB PIC programmer for all Flash devices No external power supply making it truly portable Supplied with box and Windows XP Software ZIF Socket and USB lead not incl Assembled Order Code AS3128 44 95 Assembled with ZIF socket Order Code AS3128ZIF 59 95 PICALL ISP PIC Programmer u Will program virtually all 8 mai to 40 pin senal mode AND MA parallel mode PIC15C family PIC microcontrol lers Free Windows soft ware Blank chip auto detect for super fast bulk programming Optional ZIF socket Assembled Order Code AS3117 24 95 Assembled with ZIF socket Order Code AS3117ZIF 39 95 ATMEL 89xxxx Programmer Uses serial port and any standard terminal comms program 4 LED s display the status ZIF sockets not included Supply 16Vdc Kit Order Code 3123KT 24 95 Assembled Order Code AS3123 34 95 Introduction to PIC Programming Go from complete beginner to burning a PIC and writing code in no time Includes 49 page step by step PDF Tutorial Manual Program ming Hardware with LED test section Win 3 11 XP Programming Software Program Read Verify amp Erase and 1rewritable PIC16F84A that you can use with different code 4 detailed examples pro vided for you to learn from PC parallel port Kit Order Code 3081KT 16 95 Assembled Order Code AS3081 24 95 08717 Credit Card Sales ABC Maxi AVR Development Board
10. No Compromise Oscilloscope Mao www picotech com scope421 SEVEN 2 75in SHARPENED 70mm POINTS f 2 75In Zo 70mm CONNECT TO SHARPENED POINTS GLUED BUNG PVC PIPE 4 0in id 102mm CUT OFF SCREEN CABLE TIE TO HOLD MICROPHONE CABLE MICROPHONE AERIAL konn AERIAL Fig 2 General details of the antenna construction Other oscilloscopes in this price range force you to compromise on one of the key specifications sampling rate memory depth or bandwidth The PicoScope 5000 series Is a no compromise PC oscilloscope at a price every engineer can afford Everyday Practical Electronics August 2007 01480 396395 If the voltage goes off the scale during a thunderstorm use V R 1 to bring it back with in range Low fast moving clouds will cause a wobble of the needle while a thunderstorm will cause reckless fluctuations With some observation it should be possi ble to tell at which point the needle indicates the possibility of a thunderstorm While it is a rough and ready unit the Atmospheric Charge M onitor should make an interesting desk accessory Thomas Scarborough South Africa INGENUITY UNLIMITED BE INTERACTIVE 2s IU is your forum where you can offer other readers the Os benefit of your Ingenuity ae Share those ideas earn some cash and possibly a prize 1GS s sampling rate 250MHz bandwidth 128M sample buffer memory 25M5 s
11. Table 2 Jumper Functions OUT Normal operation Erase all IDs set mode Armed output low when disarmed Armed output low when armed Disable ID add remove Enable ID add remove With the jumper in place swipe the master tag The module will perform the usual arm or disarm depending on the operating mode In addition detection of the master tag starts an internal four second timer Within that four second period any tag that is swiped will be added to memory if it does not already exist and the module will beep once Conversely any tag that already exists in memory will be removed and the module will beep twice If you try to add more that 24 tags or if the microcontroller fails to suc cessfully add or remove a tag code for any reason the module will beep four times Each time a tag is swiped the four second timer is restarted If no tag is swiped within the timing period the timer expires and the module beeps once returning to normal operation It s then necessary to swipe the master tag again before more tags can be added or removed If you install the module in an in accessible location such as inside a 21 ELECTRIC STRIKE EL 971 tI 2A a a P go 5 wall you may wish G to leave the add re gol move jumper JP3 dan in place Note that ze in some instances this could pose a On security risk If the master tag is bor r
12. and some components soldering both sides All prices include VAT and postage and packing Add 1 per board for airmail outside of Europe Remittances should be sent to The PCB Service Everyday Practical Electronics Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Tel 01202 873872 Fax 01202 874562 Email orders epemag wimborne co uk On line Shop www epemag wimborne co uk shopdoor htm Cheques should be crossed and made payable to Everyday Practical Electronics Payment in sterling only NOTE While 95 of our boards are held in stock and are dispatched within 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 photocopies of articles are available if required see the Back Issues page for details We do not supply kits or components for our projects Please check price and availability in the latest issue A large number of older boards are listed on and can be ordered from our website Boards can only be supplied on a payment with order basis PROJECT TITLE Order Code PIC Ambilux Sunset Switch Current Clamp Adaptor for Multimeters Tiptronic Style Gear Indicator JAN 06 Micro Board Display Board Hall Speed Board x Keypad Alarm 3 Way Active Crossover Jazzy Heart Status Monitor Transmitter Reciever FEB 06 Power Up MAR 06 Video Audio B
13. 1 900 HP 83731A Synthesised 1 20GHZ 5 Marconi 2032 Sig Gen 10KHZ 5 4GHZ Opt 01 02 06 Avionics HP 8648A Sig Gen 0 1 1000MHZ Gigatronic 7100 Synth 10MHZ 20GHZ internal sweep mod 130 to 15dBM Marconi 2024 9KHZ 2 4GHZ HPIB used unused Marconi 2022E Synthesised AM FM 10KHZ 1 01GHZ 500 Marconi 2019 A Synthesised AM FM 80KHZ 150 195 Metrix GX5000 Pulse Gen 50MHZ Programmable HP 3325A Synthesised Function Gen 21MHZ Everyday Practical Electronics August 2007 HP 3312A Function Gen 0 1HZ 13MHZ AM FM Sweep Tri Burst etc HP 8112A Pulse Gen 50MHZ HP 8116 Pulse Function Gen 50MHZ Gould J3B Sine Sq Osc 10HZ 100KHZ Low Distortion HP 5350B Counter 20 GHZ Marconi 2440 Counter 20 GHZ Racal 1998 Counter 10HZ 1 3GHZ Racal 1991 Counter Timer 160MHZ 9 Digit HP 53131A Universal Counter 3GHZ Opt 001 oven unused used 995 750 HP 53131A Universal Counter 225MHZ Oven ln original boxes unused used 700 600 DIGITAL MULTIMETERS HP Agilent 34401A 6 1 2 Digit 500 550 Solartron 7150Plus 6 1 2 Digit True RMS IEEE with tem measurement Fluke 77 series 2 3 1 2 Digit Handheld AVO 8 Mk6 In Ever Ready Case with Leads etc AVO 8 MK5 with Leads etc Goodwill GVT427 Dual Ch AC Millivoltmeter 10mV in 12 ranges 10HZ 1MHZ Unused L OTN D HP 8563A 6 000 MARCONI 2955A Radio Communications Test Set MARCONI 2955 Radio Communications Test Set BIRD 43 Wattmeter Many Elements Available HUNTRON 1000 Tr
14. 1 9V 150mA DC plugpack 4 small rubber feet 4 M3 x Omm machine screws with hex nuts 1 M3 x 6mm machine screw with hex nut Semiconductors 1 74HC132 quad Schmitt NAND gate IC1 1 74HCO4 hex inverter IC2 1 7805 5V regulator REG1 6 3mm red LEDs 1 1N4148 signal diode D1 1 1N4004 1A rectifier diode D2 Capacitors 1 470uF 16V PC mount electrolytic 1 100uF 16V PC mount electrolytic 3 100nF monolithic or ceramic 1 390pF ceramic Resistors 0 25W 1 14 10kQ 1 2 2kQ 3 4 7kQ 63300 18x 10kQ SIL array light and stay that way unless S2d is turned OFF again If all ofthe above happens as expect ed your simulator is working correctly and ready for use If not turn off the power and look for faulty solder joints and components fitted with reversed polarity These are the only likely causes of problems with sucha simple project EPE 4 Band Code 1 brown black orange brown yellow violet red brown red red red brown orange orange brown brown 5 Band Code 1 brown black black red brown yellow violet black brown brown red red black brown brown orange orange black black brown Everyday Practical Electronics August 2007 69 Readers Circuits Ingenuity Uniimited Our regular round up of readers own circuits 50 for all material pub We pay between 10 and lished depending on length and technical merit We re looking for novel applications and circuit designs not
15. 12 bit digital to analog converter DAC with SPI Keypad 4x4 Board Add keypad to your application Accel Board Accel is an electronic device that meas ures acceleration forces with mikrolCD support PICFlash programmer an ultra fast USB 2 0 programmer for the PIC microcontrollers Continuing its tradition as one of the fastest PIC programmer on the market a new PICFlash with mikrolCD now supports more PIC MCUs giving devel oper a wider choice of PIC MCU for further prototype development mikrolCD debugger enables you to execute mikroC mikroPascal mikroBasic pro grams on the host PIC micro controller and view variable values Special Function Regi sters SFR memory and EEPROM while the program is running All of our products are shipped in special protective boxes On line secure ordering provides fast and safe way of buying our products DEVELOPMENT TOOLS COMPILERS BOOKS EasyPIC4 Development Board with on board USB 2 0 programmer and mikrolCD m n za a a aa ze a on od ATELIERELE HARDWARE EasyPIC4 development board ICD ON BOARD Following tradition of its prede m eD cessor EasyPIC3 as one of the PROGRAMMER best PIC development systems HIGH on the market EasyPIC4 has DEVELOPMENT Performance more new features for the same TEM DEVELOPMENT price The system supports 8 14 18 20 28 and 40 pin PIC microcontrolle
16. Master tag programming The very first tag that is detected by the module after the initialisation procedure is assigned special status This master tag as we ll refer to it will be needed whenever you want to add or remove other tags Power up again and swipe the tag that you want to be assigned as the master Once the tag is within about 90 100mm of the top or bottom of the module it will beep once to indicate that the ID code has been received and stored Now whenever you swipe the tag it s unique ID code will be imme diately recognised For keyless operation Mode 1 the module beeps once and energises Everyday Practical Electronics August 2007 Fig 6 e a battery backed 12V supply is required to power the module Existing alarm systems will already have such a supply For stand alone use you ll need to wire up your own battery and charger as depicted here the door strike each time the tag is swiped For alarm operation Modes 2 to 4 the alarm state is toggled each time the tag is swiped One beep indicates system arming whereas two beeps indicate disarming You ll also note that when armed the LED flashes at two second intervals The door strike is energised as appropriate for the specific mode Adding amp removing other tags Up to 24 tag ID codes can be stored in the microcontroller s memory To enable the addition or removal of tag codes from memory first install a jumper shunt on JP3
17. The DSC family were designed from the ground up to provide all the features that users would expect from a 16 bit MCU along with a C compiler friendly instruc tion set with multiple working registers a software stack and flexible addressing modes All the devices use FLASH memory technology for program storage and can be easily programmed in circuit either by a pro grammer such as the MPLAB ICD 2 or using run time self programming M emory sizes range up to 256kB ytes for FLASH and 30kB ytes for RAM The DSP element of the processor core provides a single cycle 17 x 17 multiplier and two 40 bit accumulators supporting single cycle multiply and accumulate MAC operations traditionally only found on high end and expensive DSPs Additionally there are special DSP addressing modes that can be used to sup port FFTs Fast Fourier Transforms and digital filters It is worthwhile remembering that even though the dsPIC family has DSP fea tures itis still a highly efficient and very powerful 16 bit processor that can exe cute at up to 40 MIPS So when you need to upgrade the performance of your motor controller or perhaps provide an elaborate user interface then these devices can still be used Also recently added to the 16 bit product line are the PIC24F and PIC24H families of parts dsP1C 30F dsPIC30F dsPIC33F Family Block Diagram __ Dota Bun lt 16 bit Under the hood A full technical dis cussion of the featu
18. Vou 1 l s 2 s 8 we would have zeros at s 0 ands 3 and poles ats 2 ands 8 Gain dB Zero Significance What is the signifi cance of a zero In gen eral at a zero the gain Everyday Practical Electronics August 2007 k Gain falling by Fig 3 RC circuit with one pole and one zero will continue to increase by 20dB per decade 6dB per octave more than at lower frequencies Fig 4 shows the typical frequency response characteristics of a circuit with a single zero Note the phase shift tends towards 902 Circuit designers add poles and zeros to a circuit s frequency response in order to improve stability One important example of this is the compensation used in most op amps Fig 5 shows what the frequency response of an op amp might look like without compensation This hypothetical example has two poles at high frequencies but the gain is still much larger than 1 by the time the phase shift gets to 1802 These poles occur due to the parasitic capacitances inherent in the circuit For example the internal capacitances of the transistors and Capacitances in the interconnecting wires If we add a pole at a very low frequency then the gain will start falling off from this Fig 4 Frequency response due to a single zero 39 Fig 5 Frequency response of an op amp showing the natu rally occuring high frequency poles This circuit would be unstable with negative feedback
19. 0 6 Kg Base plate beech Working rpm approx 2 000 rpm Bearing application 6 high class ball bearings Material of the engine brass aluminium stainless steel running time 30 45 min Available as a kit 97 75 or built 101 99 www mamodspares co uk HB11 Stirling Engine Base measurements 156 mm x 108 mm x 130 mm 0 7 Kg Base plate beech Working rpm 2000 2500 rpm min run Bearing applica tion 4 high class ball bearings Material screw side parts total stainless steel Cylinder brass Rest aluminium stain less steel Available as a kit 97 75 or built 101 99 www mamodspares co uk HB12 Stirling Engine Base measurements 156 mm x 108 mm x 130 mm 1 Kg Base plate beech Working rpm 2000 2500 rpm min Bearing application 6 high class ball bearings Material screw side parts total stainless steel Cylinder brass Rest aluminium stainless steel Available as a kit 136 or built 140 25 www mamodspares co uk A HB13 Stirling Engine Base measurements 156 mm x 108 mm x 150 mm 0 75 kg Base plate beech Working rpm 2000 2500 rpm min Bearing application 6 high class ball bearings Material screw side parts total stainless steel Cylinder brass Available as a kit 97 75 or built 101 99 STEAM ENGINE KIT Everything in the kit enables you to build a fully functional model steam engine The main material is brass and the finished machine demonstrates the principle of oscillation The boiler
20. 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 Powerful tool for designing and learning Hobbyist Student 45 inc VAT Institutional 99 plus VAT Institutional 10 user 249 plus VAT Site Licence 599 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 articles 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 Electronic Projects Electronic Circuits amp Components V2 0 Analogue Electronics Digital Electronics V2 0 Hobbyist Student Analogue Filters O Institutional Electronics CAD Pack Institutiona
21. The Institutional versions now also include several types of assessment for supervisors including worksheets multiple choice tests fault finding exercises and examination questions ANALOGUE FILTERS Analogue 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 ROMS ELECTRONICS An 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 b
22. and pin 17 Select Out Note that in this case the pull up resistors have a value of 4 7kQ rather than 10kQ The remaining printer control line connects to pin 1 of the DB25 con nector This line is normally used to send the negative going strobe pulse to the printer to begin printing 68 Reproduced by arrangement with SILICON CHIP magazine 2007 www siliconchip com au each character For correct printer operation each strobe pulse should be a single clean pulse about 1 to 2us long In the simulator we generate this pulse each time switch S1 is pressed This is done by using a simple one shot circuit formed from three gatesin IC1 a 74HC132 quad Schmitt NAND device NAND gates ICla amp IC1d are connected as an RS reset set flipflop which is triggered by pressing S1 The associated 2 2kQ pull up resistor and 100nF shunt capacitor form a simple debounce circuit Diode D1 and NAND gate IC1b are used to convert the flipflop into a one shot multivibrator This works as follows normally pin 1 of IC1a is held high by the 2 2kQ pull up resistor This means that output pin 3 is normally low and so pin 11 the strobe bar out put is normally held high Because pin 3 is low D1 is forward biased and holds the voltage at the inputs of IC1b low as well As aresult the output of IC1b pin 6 is held high as is input pin 13 of IC1d Now when S1 is pressed the 100nF capacitor is discharged and so a logic l
23. eRacing packs from 11 95 12V 2 2Ah to 44Ah SLA from 6 99 Power supplies fixed and variable voltage to 15V 40A Chargers for NiCD NiMH LiPo amp SLA batteries to 12V 20A 13 8V 20A power supply with Amps display 43 87 Sample pricing eGP AA charger with 2 off 1300mAh cells 5 45 13 8V 20A Power Supply from 34 12 Probably the best range of DC model motors in the UK From under 0 5W to 1000W 1 5 to 36V Geared motors from 0 3W to 800W Ideal for most model engineering applica tions especially robotics Planetary geared motors from just 1 2g to our top of the range 750W that s 1HP weighing in at 6 35kg ti As well as motors we have wheels axles amp bearings to help complete your project Sample pricing Visit our website to see over 140 models of motor 12V 150W Motor 17 95 Geared motors from 4 70 750W 36V geared motors from 90 95 Visit our website to see over 2 000 products to order on line Need advice we offer full technical support via our FAQ forum Technobots Ltd The Old Grain Store Rear of 62 Rumbridge Street Totton Hampshire SO40 9DS Tel 023 8086 3120 Fax 023 8086 1534 Lines open Mon Thur 0900 to 1330 Established in 2001 Technobots Ltd supply a wide range of electronics and engineering products to the hobby market schools Colleges amp Universities DC motor speed controllers from 1A to 300A Various interfacing options inclu
24. flat side towards the rear of the PC board Regulator REG1 is mounted horizon tally on the top of the board with its three leads bent downwards at 90 5mm away from the body Its metal tab is then secured to the board using an M3 x 6mm machine screw and a nut underneath This also provides a small amount of heatsinking as there s a rectangle of copper underneath as well there s no need for a separate heatsink Your simulator board should now be complete apart from fitting the four rubber feet These are fitted using M3 x 9mm machine screws passing up from underneath and fitted with nuts on the top Unless of course you are using self adhesive types Check out time It s very easy to give the completed simulator a quick check out First set DIP switches S2a to S2d to their OFF positions ie towards the rear and connect a 9V DC plugpack to CON2 That done apply power and check that the first five LEDs light If they do use your DMM to check the supply volt age at pin 14 of either IC1 or IC2 it should be close to 5 00V At this stage LED6 STR should be off Now set S2d the left most DIP switch in S2 nearest the pushbutton to ON and press S1 LED6 should now 1 PC board code 627 available from the EPE PCB Service size 113 x 61mm 1 PC mount pushbutton switch S1 1 4 way DIP switch S2 1 8 way DIP switch S3 1 DB25 female connector PC mount CON1 1 2 5mm DC socket PC mount CONZ2
25. normally open or normally closed switches can be accommodated as the module automatically configures itself to suit at power up Main Features Contactless operation 90 100mm detection range No batteries in tags to go flat Stores up to 24 tag ID codes Easy tag addition amp removal Works through any non metallic material Audio feedback via on board beeper Tamper detection Arm and alarm outputs Electric door strike output Suitable for home or car use Requires 12V DC at 40mA nominal 24 Obviously the idea is that if the module is dismounted or the cover removed the switch contacts open or close changing the state of the switch input Assuming the module is armed this generates an instant alarm condition How it works All of the electronics necessary for tag reading are contained within a single epoxy encapsulated module from ID Innovations The ID 12 as it s named even includes the field coil making this an extremely compact and easy to assemble project A continuous 125kHz carrier sig nal is radiated from the ID 12 s coil while power is applied When a tag is brought within range its field coil is magnetically coupled to the reader s coil inducing an AC voltage across it Most 125kHz read only tags contain just a single IC along with the coil itself which consists of many turns of super fine copper wire To reduce overall size the coils used in miniature glass and epo
26. order to upload assembly language to a PIC processor Beginners will probably prefer to use Flowcode 3 which has poten tial advantages for experienced program mers as well The Flowcode program uses what is really quite an old idea which is for the user to produce their program in the form of a flowchart M any programmers produce a chart of this type as a prelimi nary step when producing a program In the normal course of events the program mer then writes the code for each section CFG1 CFG2 ID Locations Save to file Everyday Practical Electronics August 2007 HEX file lt C 3FFF 3FFF Fig 2 From top to bottom these E Blocks are the LED board the switch board and the 16 x 2 character LCD display board Many others are available including a prototyping board of the program gradually building up the complete program in the process The big difference when using Flowcode is that having produced the flowchart the program code is then generated automati cally In the conventional sense anyway the programmer does not actually have to do any programming However it is still necessary to understand the fundamentals of programming but it is not necessary to have a detailed knowledge of PIC proces sors and their instruction sets This approach has obvious attractions for someone who is more interested in Fig 3 left The PPP program runs in a small window but has
27. plastic both of which conduct light but not electricity So how do you send volts down a perfect insulator It s really quite easy you just shine a very bright light down the fibre and convert the photons to electrons at the far end using photovoltaics In fact the princi ple is so obvious that BT had already worked out how to do this in principle 20 years ago In those days there was no financial incentive nor was there any off the shelf technology that could turnp the boffins brainstorming into practical reality Shareholders expected telephone companies to carry on sweating the assets of their exist ing copper cable networks and it was only recently that the soaring price of copper forced phone firms like BT to reconsider Cheaper option The latest issue of trade journal FibreSystems Europe quotes Bob Cowie chief engineer of the company s infrastruc ture arm BT Openreach stating that fibre optic is now cheaper than copper to install in new buildings The most significant change in the past 12 months has been the price of copper on the world market he said It is now a cheaper option for new sites to build fibre networks from scratch Whereas the company had previously seen optical as expensive and unnecessary it iS now reconsidering its technology position in favour of installing optical fibre cable to the doorstep This applies to new buildings not those that have been cabled with copper alre
28. shrouded test leads shock proof rubber hol ster built in probe holder Be i stand Supplied fully assembled with holster battery and presentation box Features in clude Capacitance Audio Frequency Data Hold hFE Diode Test Auto Power Off Technical Specifications DC voltage 200mV 1000V AC voltage 2V 700V DC current 2mA 20A AC current 20mA 20A Resistance 2000 200MO Capacitance 2nF 20uF e Frequency 20kHz Max display 19999 Order Code MM463 Was 44 95 Now on sale at just 29 95 See our website for more special offers VAY VAY Van QuasarElectronics com Secure Online Ordering Facilities e Full Product Listing Descriptions amp Photos e Kit Documentation amp Software Downloads SHOP ONLINE AT www compactcontrol co uk Compact Control Design Compact Control Design has a range of off the shelf products designed to meet your control monitoring and acquisition needs All products use the latest technology to provide top performance in a small size and at a low cost We also provide a full hardware and software design service P0701 USB PIC USB 2 0 interface Can be bus powered or self powered Powerful PIC18F4580 Microcontroller running at 40MHz Up to 10MIPS performance All microcontroller I O pins available except RA6 RA7 oscillator and RC6 RC7 serial port Bootloader pre programmed and download software included enabling quick and
29. uses solid fuel tablets and is quite safe All critical parts boiler end caps safety vent etc are ready finished to ensure success The very detailed instruction booklet 25 pages makes completion of this project pos sible in a step by step manner Among the techniques experienced are silver soldering folding drilling fitting and testing 29 70 ref STEAMKIT Silver solder flux pack 3 50 ref SSK www mamodspares co uk HB14 Stirling Engine Base measurements 156 mm x 108 mm x 150 mm 1 kg Base plate beech Working rpm 2000 2500 rpm min Incl drive pulley for external drives Bearing application 10 high class ball bearings Material screw side parts total stainless steelCylinder brass Rest aluminium stainless steel Available as a kit 140 25 or built 144 50 www mamodspares co uk Ku So fa Q Fi 8 D a8 A HB15 Stirling Engine Base measurements 128 mm x 108 mm x 170 mm 0 75 kg Base plate beech Working rpm 2000 rpm min the engine has a aluminium good cooling Cylinder Bearing application 6 high class ball bearings Material screw side parts total stainless steel Cylinder brass Rest aluminium stainless steel Available as a kit 97 75 or built 102 www mamodspares co uk oo OO HB16 Stirling Engine Base measurements 128 mm x 108 mm x 170 mm 1 kg Base plate beech Working rpm 2000 rpm min the engine has a aluminium good cooling Cylinder Bearing application 10 high class ball bear
30. 12 bit AWG built in PicoScope 5203 32M buffer 1195 PicoScope 5204 28M buffer 1795 71 WIN AN ATLAS LCR ANALYSER WORTH 79 An Atlas LCR Passive Component READOUT Email john becker wimborne co uk wohn Becker addresses some of the general points readers have raised Have you anything interesting to say Drop us a line All letters quoted here have previously been replied to directly Analyser kindly donated by Peak Electronic Design Ltd will be awarded to the author of the Letter Of The Month each month The Atlas LCR automatically measures inductance from 14H to 10H capacitance from 1pF to 10 000uF and resistance from 1Q to 2MQ with a basic accuracy of 1 www peakelec co uk x LETTER OF THE MONTH Ideas for future articles EPE reader Edward Chase recently emailed Editor Mike with the following Dear EPE How about articles in future on these gen as EPE ever run an article on repair of surface mount boards For instance have to replace a 56 pin IC with onl 0 5mm pitch leads and could do wit some advice General advice on soldering and unsoldering SMT devices especially usi ng lead free solder would be useful Also have bought the EPE PIC Resources V2 and Flowcode CD ROMs and find that excellent though all this stuff is there is a gap in it all For instance am not a software writer apart from Fortran and BASIC many years ago and want to write some software for a PIC te
31. 44 020 8653 8888 Rechargeable Batteries With Solder Tags NIMH NICAD AA 2000mAh PP3 150mAh Instrument case with edge connector and screw terminals Size 112mm x 52mm x 105mm tall This box consists of a cream base with a PCB slot a cover plate to pro tect your circuit a black lid with a 12 way edge connector and 12 screw terminals built in 8mm pitch and 2 screws to hold the lid on The cream bases have minor marks from dust and handling price 2 00 VAT 2 35 for a sample or 44 00 VAT 51 70 for a box of 44 en Rite TILLES TEL Jane a i nh 866 battery pack originally intended to be used with an orbitel mobile telephone it contains 10 1 6Ah sub C batteries 42 x 22 dia the size usually used in cordless screwdrivers etc the pack is new and unused and can be broken open quite jf easily 7 46 VAT 8 77 pi Please add 1 66 VAT 1 95 postage amp packing per order JPG Electronics Shaws Row Old Road Chesterfield S40 2RB Tel 01246 211202 Fax 01246 550959 www JPGElectronics com Mastercard Visa Switch Callers welcome 9 30 a m to 5 30 p m Monday to Saturday FVERYDAY PRACTICAL EPP EHECTRONICS NEXT MONTH TELEPHONE DIALLER FOR BURGLAR ALARMS This project will dial a preprogrammed telephone number and send a warning tone via a modem when its input is triggered Although primarily intended to connect to the output of an alarm system it could be used for any purpose where y
32. 4people and it is modular so you can add more if required A single panel is sufficient for a 200 litre cylinder but you can fit 2 or more for high water usage or for heating swimming pools or underfloor heating Some types of renewable energy are only available in certain locations however free solar heating is potentially available to almost every house in the UK Every house should have one really And with an overall efficiency of almost 80 they are much more efficient than electric photovoltaic solar pan els efficiency of 7 15 Available in 10 20 and 30 tube versions 10 tube 199 20 tube 369 30 tube 549 Roof mounting kits 10 20 tubes 12 50 30 tube mounting kit 15 BENCH PSU 0 15V 0 2a Output and voltage are both smooth and can be regulated according to work Input 230V 21 2 num ber LCD display for voltage and current Robust PC grey hous ing Size 13x15x21cm Weight 3 2kg 48 REF trans2 i VON Se y Ii 2z k j i NEW ELECTRONIC CONSTRUCTION KITS This 30 in 1 electronic kit includes an introduction to elec trical and electronic technology It provides conponents that can be used to make a variety of experiments includ ing Timers and Burglar Alarms Requires 3 x AA batter ies 15 00 ref BET1803 AM FM Radio This kit enables you to learn about elec tronics and also put this knowledge into practice so you can see and hear the effects Includes manual with explanations about the com
33. 6mA standby Two amp Ten Channel versions also available Kit Order Code 3180KT 44 95 Assembled Order Code AS3180 51 95 Computer Temperature Data Logger Serial port 4 channel tem perature logger C or F Continuously logs up to 4 separate sensors located 200m from board Wide range of free software applications for storing using data PCB just 38x38mm Powered by PC Includes one DS1820 sensor and four header cables Kit Order Code 3145KT 18 95 Assembled Order Code AS3145 25 95 Additional DS1820 Sensors 3 95 each Most items are available in kit form KT suffix or pre assembled and ready for use AS prefix projects modules and publications Discounts for bulk quantities 177 168 DTMF Telephone Relay Switcher Call your phone number de Di mani using a DTMF phone from anywhere in the world and remotely turn on off any of the 4 relays as desired Zon User settable Security Password Anti Tamper Rings to Answer Auto Hang up and Lockout Includes plastic case 130 x 110 x 30mm Power 12Vdc Kit Order Code 3140KT 46 95 Assembled Order Code AS3140 59 95 Serial Port Isolated I O Relay Module Computer controlled 8 channel relay board 5A mains rated relay outputs and 4 opto isolated digital inputs for mea monitoring switch states etc se Useful ina variety of control and sensing applications Programmed via serial port use our new Windows interfa
34. 74HC04 hex inverter Five of the 10kQ resistors in SIL1 are used as pull ups on the input lines to prevent them from float ing at an intermediate level when the simulator is not connected to a printer or other equipment The series 10kQ resistors are used for additional protection against electrostatic charge damage to the gate inputs IClc and IC2d are used to drive LED6 which indicates the status of the Everyday Practical Electronics August 2007 strobe line This LED is illuminated when the line is low because this line is nominally active low and is off when it s high Of course the narrow nature of the strobe pulse means that in pulse mode S2d open the LED glows so briefly it s not easy to see LED6 is therefore used mainly to verify the quiescent level on the line and of course the level in non pulse mode S2d closed Power supply The only part of the circuit we haven t talked about yet is the power supply This is very simple consist ing purely of a 7805 regulator REG1 to produce a stable 5V rail from an unregulated 9V DC plugpack Series diode D2 provides reverse polarity protection while the 470uF and 100uF electrolytic capacitors provide filter ing and stability Construction Everything fits on a single sided PC board measuring 113 x 61mm and is coded 627 This is possible because we ve used board mounting components for DB25 socket CON1 DC input connector CON2 and push
35. CD ROM see next page and back issues from recent years are also available to download from www epemag com Please make sure all components are still available before commencing any project from a back dated issue APR 06 Photocopies onl PROJECTS e A Programmable Continuity Tester e Omni Pendulum e PortaPAL Public Address Amplifier Part 2 e Smart Slave Flash Trigger FEATURES e Teach In 2006 Part 6 e Consumer Electronics Show e E Chip Review e Techno Talk e PIC N Mix e Net Work The Internet Page MAY 06 PROJECTS e LED Lighting For Your Car e Smart Card Reader and Programmer e Nail Sniffer and Volts Hound e Digital Reaction Timer FEATURES e Teach In 2006 Part 7 e Practically Speaking elngenuity Unlimited Circuit Surgery e Techo Talk e PIC N Mix e Net Work The Internet a W Q e JUN 06 PROJECTS e Poor Man s Metal Locator e Widgy Box Distortion Effects For Your Guitar e Phone Ring amp Test Digital Instrument Display For Cars Part 1 FEATURES e Interface e Circuit Surgery e Ingenuity Unlimited e Techno Talk e PIC N Mix e Teach In 2006 Part 8 e Net Work The Internet Page JUL 06 Photocopies onl PROJECTS e PIC Sudoku Unit e A Dirt Cheap High Current Bench Supply e PC Power Monitor e Digital Instrument Display For Cars Part 2 FEATURES e Teach In 2006 Part 9 e Ingenuity Unlimited e Practically Speaking e Circuit Surgery e Techno Talk e
36. Connections to Differentiators Amplifiers Single Stage Amplifiers 8 sections Multi stage Amplifiers 3 sections Filters Passive Filters 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 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
37. DETAILS WITH ARM AT 5 O CLOCK ACTUATOR PADDLE TEMPLATE 3mm PERSPEX Fig 7 follow this diagram to make the side actuator knob The actuator paddle is made from 3mm thick Perspex and must be glued to the modified knob exactly as shown in the diagram at right ie in the 5 o clock position the grub screw is in the centre of the spindle s flat then tighten the erub screw using an Allen key and move the actuator lever to the centre position lablekiHiCapacitoniCodes uF Code EIA Code IEC Code 0 22uF 224 220n 0 1uF 104 100n 10nF 0 01uF 103 10n Lenk YO 0015uF 152 1n5 680pF NA 680 680p 330pF NA 330 330p 33pF NA 33 33 Value 220nF 100nF Preparing the case The next step is to remove 12 of the integral mounting pillars in the bot tom of the case so that they don t foul the PC board assembly Leave only the four pillars that line up with the corner mounting holes in the PC board itself You can use an oversize drill to remove the unwanted pillars Drilling the panels For your next hardware construction task you will have to cut the front and rear panels to size 219 x 34 5mm from 2mm sheet aluminium That done you can then drill the various holes in each panel using a photocopy of the panel artworks as a drilling template guide see Fig 8 panel and cut out the various holes using a sharp hobby knife Front and rear panel assembly Now for the rear panel assembly Be gin by inst
38. END 0xFF END 0x1FF END 0x2FF END 0xFFF regions As this is aPIC18F family proces sor the linker script identifies the areas of memory that are available using the ACCESS method accessible without messing around with bank select bits Very handy By default however the linker will try to place your variables in the gpr regions You can force the linker to place your variables in a particular region by placing a special directive in your source file prior to specifying your variables There are several directives available depending on your processor family and where you want to place the data ACCESS RAM For PIC18 family Use UDATA_ACS to put data in here Shared RAM PIC12 PIC16 family Use UDATA_SHR These are special locations available in all banks UDATA_OVR enables you to define tem porary variables that occupy the same loca tion so cannot be used at the same time This helps save space but can be danger ous to use Best avoided unless you are confident To return to normal linker con trolled allocation specify UDATA The linker is very smart and will try its best to fit your sections of code or variables into available RAM If itwon t fit in the cur rent one the linker will look for another larger region to fit it into If you have defined lots of variables in a single section it s possible that the linker will not be able to find a single memory region to put it in When this happens yo
39. HB 6015 0 83 IR Remote Control Extender MKII KC 5432 7 25 post amp packing Operate your DVD player or digital decoder using its remote control from another room It picks up the signal from the remote control and sends it via a 2 wire cable to an infrared LED located close to the device This improved model features fast data transfer capable of transmitting Foxtel digital remote control signals using the Pace 400 series decoder Kit supplied with case screen printed front panel PCB with overlay and all electronic components Requires 9VDC wall adaptor Maplin GS74R 10 99 l Electronics TI TT A Ini it Starting a new PIC project some guidance TARTING a new project is always Sita Choosing a suitable processor and getting past the blank sheet of paper software design can be an uphill struggle and it s only once you have some software running on your hardware that things settle down and you can begin to enjoy the process It s a prob lem we all suffer from This month we describe some techniques to get over this initial hurdle and introduce a few good practice design methods to help you make the most of the software you write or re use First steps The first step when starting a project is to write down the key questions that will affect your choice of processor Typically these will include How many I O pins What on chip peripherals a
40. Ingenuity Unlimited e Techno Talk PIC N Mix e Net Work The Internet Page JAN 07 PROJECTS e Balanced Microphone Preamp e Jumping Spider High Efficiency Power Supply For 1W Luxeon Star LEDs Charger For Deep Cycle 12V Batteries Part 1 FEATURES e C For PICs Part 3 e Circuit Surgery e Practically Speaking e Techno Talk e PIC N Mix Net Work The Internet Page FEB 07 PROJECTS e PIC Digital Geiger Counter e Courtesy Light Delay e Programmable Robot e Charger for Deep Cycle 12V Batteries Part 2 FEATURES e C For PICs Part 4 e Techno Talk e PIC N Mix e Interface e Ingenuity Unlimited e Circuit Surgery e Net Work The Internet Page i ki Ae U5 Sei minimi ak ie ee ee i CT PPS tet ee AA MAR 07 PROJECTS e PIC Polyphonium Part 1 Lap Counter for Swimming Pools e IR Remote Checker SMS Controller Part 1 FEATURES e Techno Talk e Practically Speaking e PIC N Mix e Ingenuity Unlimited e Circuit Surgery Net Work The Internet Page DID YOU MISS THES eee APR 07 PROJECTS e Students 20W Amp Module e Star Power PIC Polyphonium Part 2e SMS Controller Part 2 FEATURES e Ingenuity Unlimited PIC N Mix e Interface e Visual C Training Course Review e Circuit Surgery e Net Work The Internet Page MAY 07 PROJECTS e Energy Meter Part 1 e Bass Extender e Caravan Lights Check e SMS Controller Add Ons FEATURES e
41. It actually takes nearly as long to program it as it does to install it The point of all this is that this is now the basic system from the manufacturer but once installed and programmed it does exactly the same as the one at home which took about 10 minutes to set up guess all those programmable functions will be useful to some users but can t help thinking that a basic version of most electronics equipment from washing machines to burglar alarms would be useful The electronics could be identical just the firmware simplified for those that will never use and just don t want all the complexity No complications have a little iPod Shuffle which is a good example of this It does exactly what need without any complications or unnecessary controls displays etc and is to my mind a great example of how electronics should be used It seems A pple are prepared to supply a variety of iPod versions and l for one appreciate that guess just don t want to waste time trying to program systems don t need or trying to remember the settings do Electronics should be making things easier to use not more complex just because it can AVAILABILITY Copies of EPE are available on subscription anywhere in the world see opposite and from all UK newsagents distributed by SEYMOUR EPE canalso be purchased from retail magazine outlets around the world An Internet on line ver sion can be purchased and downloaded for j
42. NSW 1811 Australia Expect 10 14 days for air parcel delivery Channel Guitar Amplifier Kit The input sensitivity of each of the four channels is adjustable from a few millivolts to over 1 volt so you can plug in a range of input signals from a microphone to a line level signal from a CD player etc A headphone amplifier circuit is also included for monitoring purposes A three stage EQ is also integrated making this a very versatile mixer that will operate from 12VDC Kit includes PCB with overlay and all electronic components DC Relay Switch An extremely useful and versatile kit that enables you to use a tiny trigger current as low as 400A at 12V to switch up to 30A at 50VDC It has an isolated input and is suitable for a variety of triggering options The kit includes PCB with overlay and all electronic components with clear English instructions Programmable High Energy Ignition System Ignition System This advanced and versatile ignition system can be used on both two and four stroke engines The system can be used to modify the factory ignition timing or as the basis for a stand alone ignition system with variable ignition timing electronic coil control and anti knock sensing Kit supplied with PCB diecast case and all electronic components Features include e Timing retard amp advance over a wide range e Suitable for single coil systems e Dwell adjustment e Single or dual mapping r
43. PICKit2 places this program out of the way of your application right at the end of memory taking up 256 bytes Normally you would be completely unaware of this but it is worth noting since there must be 256 bytes of code space free for the debugger to work Normally not a problem but could be if you are writing programs that take up the full code space available J ust something worth noting for the future I ve digressed again so back to the task in hand Now we have the code and the debug executive loaded onto the PIC we can run the program in the hardware debugger and see what happens In MPLAB click on Debugger followed by Run The bottom of the MPLAB window shows the Running message just like in the simulator Indeed the user interface and features available are exactly the same only now we are running code on the tar get and at full speed Now we can see the final problem the code is running but it hasn t turned on any LEDs Time to single step the program Click on Debugger followed by Halt then Reset followed by Reset Processor This stops the program and sets the pro gram counter back to the start actually it sets the program one Instruction in That s a quirk of the debugger so don t worry about it Step through the program with the F7 key a shortcut for the Step Into debugger option Nothing surprising happens until you get to the line following
44. PSoC micro controllers with a large number of peripherals In order to con tinue working with different chip in the same development environment you just need to swich a card UNI DS3 has many features that make your development easy You can choose between USB or External Power supply Each MCU card has its own USB 2 0 programmer EasydsPIC4 Development Board Complete Hardware and Software solution with on board USB 2 0 programmer and mikrolCD The system supports 18 28 and 40 pin microcontrollers it comes with dsPIC30F4013 general purpose microcontroller with internal 12 bit ADC EasydsPIC4 has many features that make your development easy Many of these already made examples in C BASIC and PASCAL language guaran tee successful use of the system Ultra fast on board pro grammer and mikrolCD In circuit Debugger enables very efficient debugging and faster prototype developing EasyARM Development Board with on board USB 2 0 programmer ss EasyARM board Cae comes with Philips LPC2214 microcontroller Each jumper element and pin is clearly marked on the board It is possible to test most of industrial needs on the system temperature controllers counters timers etc EasyARM has many features making your devel opment easy One of them is on board USB 2 0 programmer with automatic switch between run and programming mode Examples in C language are provided with the board EasyAVR4 Development Bo
45. The ABC Maxi is ideal for developing new designs Open architecture built around an ATMEL AVR AT90S8535 microcontroller All circuits are embedded within the package and additional add on expansion modules are available to assist you with project development Features 8 Kb of In System Programmable Flash 1000 write erase cycles e 512 bytes internal SRAM e 512 bytes EEPROM e 8 analogue inputs range 0 5V e 4 Opto isolated Inputs I Os are bi directional with internal pull up resistors e Output buffers can sink 20mA current direct LED drive e 4x 12A open drain MOSFET outputs e RS485 network connector e 2 16 LCD Connector e 3 5mm Speaker Phone Jack e Supply 9 12Vdc The ABC Maxi STARTER PACK includes one assembled Maxi Board parallel and serial cables and Windows software CD ROM featuring an Assembler BASIC com piler and in system programmer Order Code ABCMAXISP 89 95 The ABC Maxi boards only can also be purchased separately at 69 95 each Controllers amp Loggers Here are just a few of the controller and data acquisition and control units we have See website for full details Suitable PSU for all units Order Code PSU445 8 95 Rolling Code 4 Channel UHF Remote State of the Art High secu mi rity 4 channels Momentary or latching relay output Range up to 40m Upto 15 Tx s can be learnt by one Rx kit includes one Tx but more 7 available separately 4 indicator LED s Rx PCB 77x85mm 12Vdc
46. a negative feedback circuit connected around IC2a the boost or cut action is achieved without causing any significant distortion or increase in signal noise level Balance control The output signals from IC2a are then fed via a 4 7kQ series resistor and a 1uF non polarised NP capacitor to the 50 1 38mm red LED LED2 1 3mm orange LED LEDS 4 1N5404 3A diodes D1 D4 Capacitors 4 2200uF 25V electrolytic 2 470uF 16V electrolytic 4 220uF 25V electrolytic 2 4 7uF 16V NP electrolytic 2 1uF 16V NP electrolytic 4 220nF 50V MKT polyester 8 100nF 50V MKT polyester 2 10nF 50V MKT polyester 4 1 5nF 50V MKT polyester 2 680pF 50V disc ceramic 2 330pF 50V disc ceramic 2 33pF 50V disc ceramic Resistors 0 25W 1 2 270kQ 4 4 7kQ 4 82kQ 4 2 7kQ 2 56kQ 3 1kQ 6 27kQ 2 4700 4 10kQ 2 100Q 2 5 6kQ 2 10Q 2 2 Q Potentiometers 1 PC mount 16mm dual 10kQ log pot VR1 1 PC mount 16mm dual 100kQ linear pot VR2 1 PC mount 16mm dual 50kQ linear pot VR3 1 PC mount 16mm 50kQ linear pot VR4 positive input of IC3 which is the power amplifier IC for the left channel We ll look at this in amoment but first note that one end of pot VR4 the Balance control is connected to the junction of the 4 7kQ resistor and 1uF NP capacitor Because the moving wiper of VR4 is connected to ground this means that the 4 7kQ resistor and the associated half of VR4 form a variable voltage divider while the other ha
47. and should be done before buying any parts because there is a potential problem that can occur at this point M any of the peripheral functions of the PIC share port pins with other features such as I O lines It s not uncommon to find a PIC that appears perfect but when you come to wire it up in your circuit design you find that all your I O pins are used up before you can connect the UA RT or SPI bus When this happens it s back to the list of processors to find a part with more I O pins If you are lucky enough to have chosen a part that is supported by your debugger then you can start coding and testing immediately If not or you do not have a debugger then you will have to wait until you have built your target hardware Alternatively if you have a suitable board with a similar processor you could start developing parts of your software but this can be difficult and awkward to move back to your target processor B etter to wait until your real hardware is ready Assuming you have your circuit or a debugger available it s time to start cutting code But before you open your text editor and start typing it s worth first thinking about how you will organise your code Can re use any routines either my own or from another source Will any of the code am about to write be useful in anoth er project W hat we are trying to do at this point is separate the code into different source files in such a way that the
48. arising from this is that you need to convert a standard 20mm knob into a custom side actuator lever knob to allow the switch to be operated via a lever which emerges through a matching slot in the front panel It s not hard to make this special knob as we shall see later Board assembly Before installing any of the parts it s a good idea to carefully inspect the copper side of the PC board for manufacturing defects In particular make sure that there are no bridges between pads or tracks or breaks in the tracks and make sure that all the holes have been drilled If everything checks out OK you re ready to start the assembly Fig 6 shows where all the parts go Begin by fitting the eight wire links to the board followed by the resistors and the MKT and ceramic capacitors Table 2 shows the resistor colour codes although it s a good idea to also check each value using a digital multimeter before it is installed on the board That s because some of the colours can be difficult to read Next install the four rectifier diodes D1 D4 Zener diodes ZD1 ZD2 and the two TLO72 ICs IC1 and IC2 These parts are all polarised so make sure they go in the right way around By the way don t fit the rectifier diodes with their bodies right down against the board instead mount them so that each diode body is about 4mm above the board This provides some ventilation and also reduces any interference coupling to the
49. at high frequencies with varying loudspeaker loads Power supply Both IC3 and IC4 operate from dual supply rails of 22V DC This gives a total DC supply of 44V necessary for the power amplifier stages to develop the power we want into 8Q loudspeak ers with low distortion We generate the 22V and 22V sup ply rails from the external plugpack s supply voltage of 16V AC using four half wave rectifier circuits one each for the positive and negative rails for IC3 and IC4 Each rectifier circuit uses a single 1N5404 diode and a 2200uF reservoir capacitor and they re all kept separate to minimise crosstalk between the two channels Should a suitable plugpack not be available a 20VA mains transformer with 15V secondary can be used This should be mounted in a seperate earthed metal box with suitable mains fuse only use this option if you have the necessary knowledge to safely wire up mains powered equipment The input preamp and tone control stages around IC1 and IC2 don t need to Everyday Practical Electronics August 2007 p YACC nce d poz di WO 44001 mozze 4noozz m 4U00 4YOOL ee ooz vi TAGCT YAcT 128 LNO wIVAdS OLZ IHON gri YATZ VOL dN zY f T1AZI I AL V eo Ino JINVIS VLTZ 491 TAGCT ASZ rozz ASZ rozz YJACC JYOOL IZ JONVIVE Nn 0S YAA z AST Joozz lt ASZ arioozz 19S Q WILNMdWU 039319 NI
50. carry out this sequence of operations in our application a timer interrupt routine is used Timer 2 is ini tially set up to interrupt the processor every 5 7ms 175Hz At this point the output drive signal is overridden by setting OVDCON 0x0001 which will iso late one motor termi nal but leave the other connected to ground through the low side FET The timer is recon figured to interrupt 1ms later after the back EMF voltage has sta bilised Following this the ADC reading is taken and the MCPWM is subsequently restarted again by writing to OVDCON Fig 3 shows the voltage measured across the motor along with an indicator trace showing the time during which the ADC Sample is actually taken Based upon the measurement of back EMF itis possible to calculate the RPM of the motor and hence provide a deviation as an error signal into our control algorithm However if you were to monitor the read ings consecutive samples are likely to vary quite considerably This is because the motor will have a number of windings and each one will have a slightly different resistance which will affect the back EMF Furthermore each of the contact points on the commutator will wear in a different way causing additional errors To overcome this we could perform a simple running average calculation however we are going to delve into a little bit of DSP and use the power of the dsPIC DSP to rap idly perform a filtering operation Th
51. code in each file is largely independent of the other source Everyday Practical Electronics August 2007 files This makes bigger programs much easier to write Ten fifty line files are much easier to read and comprehend than one five hundred line file This is always the hardest part starting with a blank sheet of paper every writer s nightmare Thinking about how you will split your code is a good way to break past this initial blank sheet impasse and will help you write easy to debug re useable code A win win scenario Example project Let s take a hypothetical example of a simple project that includes a PIC an embedded GPS receiver an LCD and a small EEPROM memory The unit displays the current position on the LCD and stores the location into the EEPROM every minute The GPS module connects to the UART onthe PIC whilethe EEPROM con nects to the SPI interface Taking an example like this would sug gest a division of software into source files like this main asm gps asm eeprom asm main asm will hold all of the top level application code and the initial hardware setup gps asm will hold the routines to read the current location from the GPS module and eeprom asm holds the code to manage storing GPS locations This is a good start but we can do bet ter The GPS module is going to contain generic UART receive and transmit rou tines that would be useful in other proj ects Those generic routines wou
52. cost paper composite or os a re Single amp Double sided Other sizes also available Paper Glass Fibre Size Single Double nge Double 4x 6 1 47 1 82 1 89 2 17 6x12 4 20 5 04 5 60 6 23 x 6 30 7 70 8 40 9 38 2 10 78 e 2 38 2 6 3 01 220 x 100mm 3 08 3 71 233 x 160mm 4 83 233 x 220mm PCB Production Chemicals Aerosol Photoresist spray covers 2m Powder developer makes 1 It Powder developer makes 10It Ferric Chloride Pellets makes 500m Ferric Chloride Pellets makes 1It Ferric Chloride Pellets makes 5lt Clear Fine etch crystals makes 5lt Tin Plating Powder makes 1It Aerosol Flux spray Aerosol PCB Laquer spray 6 83 Tools Cutters amp Strippers We carry a wide range of specialist tools for the elec tronics Industry including Side Cutters 130mm Low cost 115mm Draper 115mm Box Jointed 145mm Long reach Wire Strippers 130mm Low cost 150mm Draper 5mm2 5 86 Tools Ratchet Crimping Pliers High quality ratchet crimping pliers for various terminal including Automotive Data Power and Data connections Red Blue Yellow 15 80 BNC TNC RF series 15 08 7 RJ11 12 Data Series E222 RJ45 Data Series 20 43 RJ 1 12 amp 45 Series 11 83 CK Tools Crimp Pliers Green Red Blue 24 38 Red Blue Yellow 22 88 0 24 2 5mm crimps 26 01 0 5 6 0mm crimps 26 01 Non insulated crimps 24 38 Cable Ribbo
53. everything needed to load PIC assembly language pro grams and send them to a wide range of PIC chips Common PPPv3 Progs 18 3FFF _ Fig 5 This pop up window shows the memory contents of the PIC chip fitted in the Multi programmer 63 electronics than in programming and would like a quick and easy means of using PIC processors With experienced pro grammers it has the advantage of enabling many programs to be produced more quickly than could be achieved using con ventional programming techniques In the past this method has been used as the basis for programming languages for PCs and other computers but it has not been very successful W hen applied to gen eral programming there is a tendency for things to become overcomplicated so that the simple programming language is actu ally far from simple to use It works much better in the current context where it is being applied to a specialist form of pro gramming and to microprocessors that have relatively small instruction sets The system can be implemented in a worth while fashion while remaining reasonably straightforward On the block Flowcode 3 installs without difficulty under Windows XP Any necessary add ons that are not already present will be installed automatically When run the program has a conven tional appearance Fig 6 with the usual menu bar at the top and a toolbar immedi ately below it The toolbar duplicates and provides quick a
54. everything they need to know about the architecture of these new chips how to program them how to test them and how to debug them Lucio s common sense practical hands on approach starts out with basic functions and guides the reader step by step through even the most sophisticated programming scenarios Experienced PIC users and newcomers alike will benefit from the text s many thorough examples which demonstrate how to nimbly side step common obsta cles and take full advantage of all the new features 496 pages CD ROM ROCAR CAVE 32 50 NEWNES PC TROUBLESHOOTING POCKET BOOK THIRD EDITION Howard Anderson Mike Tooley All the essential data for PC fault finding and upgrading This book provides a concise and compact reference that describes in a clear and straightforward manner the princi ples and practice of fault finding and upgrading PCs and peripherals The book is aimed at anyone who is involved with the installation configuration maintenance upgrading repair or support of PC systems It also provides non techni cal users with sufficient background information charts and checklists to enable the diagnosis of faults and help to carry out simple modifications and repairs In order to reflect rapid changes in computer technology both hardware and soft ware this new edition has been completely revised 256 pages Order code NE41 20 50 75 Theory and Reference ELECTRONIC CIRCUITS FUNDAMENTALS amp AP
55. 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 Maestro and MasterCard accepted Send fax or phone your card number card expiry date and card security code the last 3 digits on or just under the sig nature strip with your name address etc Or order on our secure server via our UK web site Overseas cus tomers your credit card will be charged by the card provider in your local currency at the existing exchange rate Phone 01202 873872 ay 01202 874562 Email stewart kearn wimborne co uk Editor MIKE KENWARD Consulting Editors DAVID BARRINGTON JOHN BECKER Business Manager DAVID J LEAVER Subscriptions MARILYN GOLDBERG General Manager FAY KEARN Editorial Admin 01202 873872 Advertising Manager STEWART KEARN 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 accom
56. feature electrically operated pumps and or heaters with thermostat control suitable for boards upto 320 x 260mm Universal Tank with heater Model 333 007 169 58 Bubble etch Tank with heater amp bubble pump Model 333 004 208 48 PCB Production Tools Drill Bits HSS parallel shank bits available in sizes from 0 3mm to Omm 0 3 0 95mm in 0 05mm steps 0 60ea 4 00 10 1 0 2 0mm in 0 1mm steps 0 40ea 3 60 10 HSS Reduced shank 2 35mm bit available in sizes from 0 6mm to 1 7mm in O mm steps 0 84ea 7 60 10 Reground Tungsten carbide reduced shank available in sizes from 0 6 to 1 6mm in 0 1mm steps Drilling Machines Expo Reliant 12V drill 3 8mm capacity 8400rpm 12 78 Expo Zircon 12V drill 3 8mm capacity 11900rem 14 20 Minicraft MX1 230V 8000 21000rpm with chuck amp collet Model EPE270 390 Normal price 48 51 Any of these items carriage 5 50 SPECIAL PRICE gi 31 02 Servisol Products Aerosols 200m Switch Cleaner Freezer Foam Cleanser Cleaner lubricant Vide Head Cleaner Aero Klene Aero Duster Cold Clean Label remover Isopropyl alcohol Heatsink Compound Heatsink Compound Silicone grease Bench Power Supplies A range of mae output ro gared bench power sup pi with variable voltage amp current limiting Features hort circuit and Foldback overload protection Metal case with on off switch outputs via Red Black amp Green Earth 4mm shrouded sockets z
57. 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 A roundup of the latest Everyday News from the world Frank Mobile Admissions Much of what is offered for mobile comms is just not wanted so finds Barry Fox EVENUE from simple SMS text mes Saging is paying for the WAP web and 3G services that many phone users either do not want or cannot make work The refreshingly frank admission came from a Consumer Electronics Conference The Digital Marketplace held in London recently by electronics industry body Intellect Dr Norman Lewis was billed as Director of Technology Research at Orange but explained that he had recently left Orange is now Chief Strategy officer with Wireless Grids Corp of USA and thus able to speak more freely about the cellphone industry s mistakes Lewis predicted that today s digital children will disrupt the future with arise of bedroom culture and decline of street culture My message to you he told the audi ence of manufacturers is that CE like
58. for the novice wishing to get started in the fascinat ing world of FM broadcasting 45x145mm Kit Order Code 1028KT 23 95 Assembled Order Code AS1028 31 95 Credit Card Sales 0871 717 7168 QUASAR electronics Get Plugged In Electronic Project Labs Great introduction to the world of electron ics Ideal gift for budding electronics expert 500 in 1 Electronic Project Lab Top of the range Com plete self contained elec tronics course Takes you from beginner to A Level standard and beyond Contains all the hardware and manuals to assemble 500 projects You get 3 comprehensive course i books total 368 pages Hardware Entry Course Hardware Advanced Course anda microprocessor based Software Program ming Course Each book has individual circuit explanations schematic and connection dia grams Suitable for age 12 Order Code EPL500 149 95 Also available 30 in 1 15 95 130 in 1 37 95 amp 300 in 1 59 95 details on website Tools amp Test Equipment We stock an extensive range of soldering tools test equipment power supplies inverters amp much more please visit web site to see our full range of products Precision Digital Multitester 4 5 Digit A highly featured high precision digital multime ter with a large 4 5 digit LCD display High accu racy 0 05 Auto zeroing polarity selection and over range indication Supplied complete with
59. have to think about it later Configuring your assembler to accept multiple files may be complicated which makes getting it right first even more important If you are using MPLAB then you can refer to the current tutorial on the Subject in other pages of this magazine Configuration bits Once you have the empty source files in place it s still not yet time to start writing code we ll get there eventually the final step before this is to choose your con figuration settings The important point here is to not concern yourself with the fine tuning of these code protection power up timers and special peripheral option selec tion can come later as you add code and refine the operation on the target hardware Concentrate on the absolute minimum nec essary after all you haven t written any code yet Start by specifying the oscillator mode turn the Watchdog Timer off and set any other critical features that will cause even the simplest of programs to work on your hardware Y ou set the configuration bits in a single source file any file but typical ly the main source file main asm Don t forget the choice of filenames is complete ly down to you these are just examples and are the author s personal preference and style So you have some files and configura tion setting now finally it s time to write some code At first it s important to keep things simple With new software and new hardware i
60. is mul tiplied by the P gain giving a control response that is a function of the error magnitude When first tuning a PID controller the and D terms will be set to zero and P adjusted until the system responds well to changes in speed set point So for the motor we adjust P until it speeds up and slows down in a suitably short time without overshooting too much As the motor speed gets closer to the set point value the error will reduce In most systems though this error will never get to zero and a small steady error signal will remain The or integral term is used to remove this error The term creates a con tinuous running total of the error signal thus accumulating errors until they are large enough to affect the controller output The term should be set to a small value as large values can cause oscillation Finally the differential or D term can be used to improve the system response to control changes By applying a differential input the rate of change of the error signal is monitored so that rapid control input changes can be tracked more easily M any systems and our motor controller do not need to use D and will set this term to zero So far we have rather convenientiy omit ted giving any actual values for the terms so how are the values arrived at In the case of the dsPIC DSP library the PID function assumes that the reference con trol and meas ured values are all normalised in some manner To ach
61. it s vital to glue the actuator paddle to the knob in the correct position ie with the arm at 5 o clock to the grub screw see text and Fig 7 Reproduced by arrangement with SILICON CHIP magazine 2007 www siliconchip com au panel using three 6G x 9mm screws then secure the pots to the front panel using the supplied nuts and washers You are now ready to bolt the two LM1875 audio output devices IC3 and IC4 to the rear panel along with the finned heatsink Fig 9 shows the mounting details First check that the area around the mounting holes is smooth and free of any burrs That done apply thermal grease to the various mating surfaces see Fig 9 then slip the two LM1875 devices into position on the PC board Finally bolt them to the rear panel between mica wash ers along with the heatsink using two M3 x 16mm screws Don t leave out the insulating bushes that go through the device tabs and make sure that the mica washers are prop erly aligned before tightening the mounting screws Tighten both mounting screws so that the tab of each IC is clamped flat against its mica washer and the rear panel Once that s been done set your multimeter to a low ohms range and use it to confirm that the device tabs are indeed electrically isolated from the rear panel If either device Everyday Practical Electronics August 2007 Input Source Selector Left Speakers Q lt O 2 1 epi C
62. it is always the pannin feature that lets it down due to support of a limit ed set of printers 7 have recently discovered a useful utili ty that provides a software emulation of an Epson dot matrix printer but then sends its 72 Say nothing about the software structure so there is no Ney can pick a similar pro ject to mine and find in EPE or the website a flowchart or even commented assembler to get ideas E dward Chase via email Mike replied to Edward Thanks for your suggestions The SMT problem is not one we have covered it does tend to require special equipment and is not an area any hobbyists would get involved in have forwarded your email to John Becker for his comments regarding PIC programming replied to Edward saying My PIC Tutorials have only been intend ed to tell people about low level PIC pro gram writing Others such as M ike Hibbett ave been giving recent advice about using higher level code writing asin C As far as flow charts go never use them and itis rare for other authors to do so either Even Microchip do not use many in their data books personally feel that visualising a process in one s head is quite adequate but that is not something that can be taught To me flow charts for the sort of software EPE publishes are basically not needed and can confuse the thought processes unless expertly done Some of the contributors would not claim to be experts but have
63. m PAPER OUT SELECT IN ERROR AUTO LF RESET Dm pa zlo setecrour A C S2a c 18 25 SET CONTROL GROUND PINS l ON L OFF H D2 E 1N4004 5V K A w CON2 i 9VDCIN 100uF 470pF PRINTER PORT SIMULATOR OV Fig 1 the circuit is straightforward just some DIP switches to set the data bits and control pins a flipflop to generate the strobe pulse and some indicator LEDs to monitor the status lines Everyday Practical Electronics August 2007 67 r AY val NE 4 o LL Li x LPT INTERFACE p LIJTIJI II S AN ZE essen es l ZAN COOLIO I OLO IO IO OOJOO CD ICD ICD CD ID IOD ICD ICD ICD Fig 2 install the parts on the PC board as shown here taking particular care to orientate the DIP switches correctly In addition switch S1 must be installed with its flat body surface to the left Fig 3 this is the full size etching pattern for the PC board Check your board carefully before installing any of the parts Conversely when a switch is open ed that data line is pulled to logic high ie 5V by the pull up resistor As a result the DIP switch can be used to feed any desired extended ASCII data bit combination to the printer or other device ie from 00 to FF hex Similarly 4 way DIP switch S2 is used to set any desired combination of bits on three of the four control lines of the port ie pin 14 Auto LF pin 16 Reset
64. mailing Offices POSTMASTER Send address changes to Everyday Practical Electronics c o Express Mag PO Box 2769 Plattsburgh NY USA 12901 0239 Published on approximately the second Thursday of each month by Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Printed in England by A pple Web Offset Ltd Warrington WA 1 4RW Distributed by Seymour 86 Newman St London W1T 3EX Subscriptions INLAND 18 75 6 months 35 50 12 months 66 2 years OVERSEAS Standard air service 21 75 6 months 41 50 12 months 78 2 years Express airmail 30 75 6 months 59 50 12 months 114 2 years Payments payable to Everyday Practical Electronics Subs Dept Wimborne Publishing Ltd Email subs epemag wimborne co uk EVERY DAY PRACTICAL ELECTRONICS is sold subject to the following conditions namely that it shall not without the written consent of the Publishers first having been given be lent resold hired out or otherwise disposed of by way of Trade at more than the recommended selling price shown on the cover and that it shall not be lent resold hired out or otherwise disposed of in a mutilated condition or in any unauthorised cover by way of Trade or affixed to or as part of any publication or advertising literary or pictorial matter whatsoever PoScope is a low cost USB based instrument that adds invaluable test equipment features to your desktop or notebook PC Being PC ba
65. more efficient ways of doing things will evolve for program writers as they become more experienced capture and process output from pretty much any program as long as the program can print to an LPT port and can generate data in the old Epson dotmatrix ESC format hope this helps Richard and your other readers to continue to use those tried and trusted favourite applications for a few more years David Whale via email Thank you David let s hope it helps any readers who share the same problem including Richard and myself Everyday Practical Electronics August 2007 EPE website Dear EPE Re the website problem dealt with in Readout May 2007 have installed J ava the verify button confirms it is installed but still cannot open the applet top right hand of your home page have Norton Internet Security 2007 Installed do not have an icon for J ava Any ideas please John Speller via email Alan Winstanley replied to J ohn found an old ish reference to this on the Symantec web site and it LE be that the security software is blocking the running of Java applets http servicel symantec com SUP PORT sunset c2001kb nsf pfdocs 2000050935683265 0 pen Document amp E xpandSection 2 could not see any settings elsewhere that would block n If it works OK in e g Firefox web browser but not in Microsoit IE then it s the probably the web browser If it doesn t work in Firefox either then it is p
66. more software than e Supports all EOBD and OBD II any other OBD interface protocols e Inexpensive v 1S015765 4 CAN e Full Speed USB 1 1 v ISO14230 4 Keyword 2000 Automatic protocol detection v ISO9141 2 e Package includes cables software v 1850 VPW CD and Quick Start Guide v J1850 PWM Buy from your local UK distributors www ElmScan5 com epe veni n vit mi RETO A ye OP RANN L Aa in TEF a j ti BA fam R Maki k Esr m a Ne dri aan i Everyday Practical Electronics magazine EPE has been published since 1971 We distribute approx 20 000 copies per month This is broken down into two sections subscriptions and news stand sales Our 3 000 subscribers are mainly in the UK but we do have a large market in USA Australia New Zealand and Canada We also supply copies to schools colleges universities and company training facilities Publication Da at 2nd Thursday of preceeding month 60 of our readers buy from mail order advertisers 67 of our readers buy 10 or more issues of EPE a year 75 of EPE readers do not regularly read any other electronics magazine 90 of our readers have PCs a further 6 have access to a PC 8 Under 18 years old 7 18 21 years old 13246 22 29 years old 15 30 39 years old Q 14 Trainees Students 3 Teachers Lecturers Trainers 23241047 years old o T 14 50 60 years old 1224 Engineers 19 Technicians 20 60 id The remainder of the readership class themselves as hobbyist
67. n 3 Right Balance Fig 8 these full size artworks can be photocopied and used as drilling templates for the front and rear panels if necessary They can also be copied onto adhesive back paper and used to make the final dress panels see text 57 Rear Panel amp Heatsink Assembly M3 x 16mm SCREW HEATSINK SMEAR THE FOLLOWING SURFACES WITH A THIN FILM OF HEATSINK COMPOUND REAR METAL FACE OF LM1875s BOTH SIDES OF MICA WASHERS ENTIRE REAR SURFACE OF HEATSINK AREAS OF REAR PANEL WHICH WILL MICA WASHER NYLON BUSH Ye NUT FLAT WASHER IC3 AND IC4 LM1875 U PC BOARD REAR PANEL 2mm THICK LUMINIUM CONTACT THE HEATSINK amp MICA WASHERS Fig 9 follow this diagram to mount the heatsink and audio amplifier ICs IC3 amp IC4 on the rear panel Note that the amplifier tabs must be isolated from the panel metalwork using mica washers and insulating bushes tab shows a short to the rear panel the assembly must be dismantled and the fault located Assuming everything is OK remove the PC board and panel assembly from the case and solder the pins of each LM1875 device The internal wiring can now be completed by running figure 8 speaker cable between the loudspeaker terminals and the PC board Finally refit the assembly to the case and fit the knobs to the pot spindles You are now ready for the smoke test Checkout time OK connect a 16V AC plu
68. n Me gol po Ne l m page da eA EN Y ina programming software SOFTWARE C FOR 16 Series PICmicro VERSION 4 The C for PICmicro microcontrollers CD ROM 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 PICmicro 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 PICmicro microcontrollers Highly interactive course 8 Virtual C PICmicro improves understanding 9 Includes a C compiler for a wide range of PICmicro devices 8 Includes full Integrated Development Environment Includes MPLAB software Compatible with most PICmicro programmers Includes a compiler for all the PICmicro devices Minimum system requirements for these items Pentium PC running Windows 98 NT 2000 ME XP CD ROM drive 64MB RAM 10MB hard disk space a J rs 1 a Be a a ee pi Ge Gi ae Gee ee YO Ii ri r PS trih aia i a IE e I ee 158 including VAT and postage supplied with USB cable and 40 OFF Buy the Development Board together with any Hobbyist Student or Institutional versions of the software CD ROMs listed b
69. of EPE Well you can just take out a one year subscription and save 54p an issue or 6 50 over the year You can even save 75p an issue if you subscribe for two years atotal saving of 18 00 Overseas rates also represent exceptional value You also Avoid any cover price increase for the duration of your subscription 8 Get your magazine delivered to your door each month e Ensure your copy even if the newsagents sell out Order by phone or fax with a credit card or by post with a cheque or postal order or buy on line from www epemag co uk click on Subscribe Now SUBSCRIPTION ORDER EPE SUBSCRIPTION PRICES FORM Subscriptions for delivery direct to any address in the UK A 6 months 18 75 12 months 35 50 two years 66 Overseas oe 6 Months UK 18 75 Overseas 21 75 6 months 21 75 standard air service or 30 75 express airmail standard air service 30 75 express airmail 12 months 41 50 standard air service or 59 50 express airmail 1 Year UK 35 50 Overseas 41 50 standard air service 24 months 78 standard air service or 114 express airmail 59 50 express airmail Cheques or bank drafts in sterling only payable to Everyday 2 Years UK 66 00 Overseas 78 00 standard air service Practical Electronics and sent to EPE Subs Dept Wimborne 114 express airmail Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset
70. of interest is labelled alarm It can be wired to a normally open input on the main control unit to signal an alarm con GND dition This output is switched on when the tamper circuit is activated see below and also when three consecutive unknown tag IDs are detected An on board piezo buzzer beeps and a LED flashes for the duration of an alarm which is set at five minutes After the alarm period the alarm output is switched off but the LED continues to flash at a fast rate until the module is disarmed For stand alone use the alarm output can be used to drive a 12V DC siren with a rating of 600m lt A or less For larger loads this output can also be used to drive a 12V relay 25 Fig 2 REG1 and diode D2 must be mounted on the copper side of the board as shown here Attach REG1 to the board using an M3 screw nut and washer before soldering its leads Tamper protection If the module is mounted in an ac cessible location it s quite possible that someone may try to detach the assem bly or remove a cover in an attempt to bypass security For this reason we ve included a tamper function that can be used to detect such interference The digital input which we ve la belled tamper switch can be wired to one side of a tamper switch reed switch or mercury switch depend ing on the installation The other side of the switch goes to the ground negative input see Fig 6 d Either
71. of the phase shift produced by the capacitor T he output volt age is therefore A Vou Vi JR ee The reactance effective resistance of the capacitor is X c 1 22fC where f is the signal frequency We can put some exam ple numbers into this equation if R1 is 1kQ and C 100nF and the signal V n is 2V at a frequency of f 1kHz then Xc is 1592 and so V oy iS 1592 1880 Vin 0 847V in 1 69V We know our output sig nal amplitude and hence the gain of the cir cuit that is V qut V in is 0 847 or 1 44QB But something is missing what is the phase shift The formula we have used has told us nothing about phase shift but we know that the combination of gain and phase shift is critical when analysing sta bility The problem occurs because our expression for the reactance of the capac itor Xc 1 2mfC only contains frequency and not phase shift A ctually we can also find a formula for the phase shift pro duced by this circuit but to do more use ful analysis we have to be able to handle both phase shift and frequency simultane ously This is where the advanced maths comes in Deeper Analysis We get rid of the simple frequency value 2af and replace it with a complex fre quency variable denoted by s So now Xc 1 SC but s is not an ordinary number it is two dimensional complex number that is able to encompass the effects of frequency and phase The voltages in the circuit must now also be repre
72. on the CD ROM and you can customise the designs as required WHAT S INCLUDED Light Modules Temperature Modules Sound Modules Moisture Modules Switch Modules Astables including 555 Remote Control IR amp Radio Transistor Amplifiers Thyristor Relay Op Amp Modules Logic Modules 555 Timer PIC PICAXE Output Devices Transistor Drivers Relay Motor Direction amp Speed Control 7 Segment Displays Data sections with pinouts etc Example Projects Full Search Facility Further Background Information and Animated Diagrams Runs in Microsoft Internet Explorer eee e e a All circuits can be viewed but can only be simulated if your computer has Crocodile Technoloy version 410 or later A free trial version of Crocodile Technology can be downloaded from www crocodile clips com Animated diagrams run without Crocodile Technology Single User 39 00 inc VAT Multiple Educational Users under 500 students 59 00 plus VAT Over 500 students 79 00 plus VAT UK and EU customers add VAT at 17 5 to plus VAT prices DIGITAL WORKS 3 0 Counter 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
73. or build your own We will use the 44 pin demo board that is supplied with the PICK it2 to act as our target hardware This board comes with a PIC 16F 917 processor hence the original choice of that CPU for the tutori al and eight LEDs con nected to PORTD Starting the debugger To start using the debug ger first plug your PICK it2 unit into the demo board then connect the PICK it2 to your PC using the supplied USB cable All power for the demo board and PICK it2 come from the PC via the USB cable so no need for batteries or addi tional power sources On ce connection has been made the PICKit2 should illumi nate its green power LED to indicate all is well Open the MPLAB proj ect workspace file that you created following last month s article by double clicking on the test mcw file MPLAB will start and E Output display the windows and files as you last left them The orange target LED should now illuminate indicating that MPLAB has automatically detected the PICK it2 and is ready to start using it To make sure that the project program hex file is up to date select Project fol lowed by Quickmake to rebuild the source file Debugging on the target hard ware is very similar to debugging in the simulator with the exception that for hard ware debugging we must first download the program file into the target hardware s flash memory To do this select Debugger the
74. 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 ner s 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 com puter building The extra big format makes it easy to see what s going on in the pictures The author goes under the hood and shows step by step how to create a Pentium 4 computer or an Athlon 64 or Athlon 64FX cov ering What first time builders need to know How to select and purchase parts How to assemble the PC How to install Windows XP The few existing books on this sub ject although badly outdated are in steady demand This one delivers the expertise and new technology that fledg ling computer builders are eagerly looking for 228 pages 224 pages large format RoC R EH C1 na 16 99 THE PIC MICROCONTROLLER YOUR PERSONAL INTRODUCTORY COURSE THIRD 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 trans forming electronic project
75. people has to be connectable you have to solve that problem of how to connect K ids Second Annual Schmartie Awards SchmartB oard the developer of a tech nology that has simplified the creation of electronic circuits for hobbyists education and industry has announced the Second Annual Schmartie Awards Entrants have until the end of the year to design and submit SchmartM odule cir cuits SchmartM odules are functional cir cuit blocks such as RS232 or power sup plies that physically connect to other SchmartB oards to facilitate prototyping To participate post a schematic and photo of the finished circuit on the SchmartB oard website along with a bill of materials including the correct SchmartBoard part numbers The grand prize is 1000 and the creation of a SchmartM odule based on the winning circuit design SchmartB oard will market the SchmartM odule worldwide and the winner will also receive a 10 commis sion to be paid quarterly The winner will receive worldwide recognition as his or her name will be silk screened on the product as the SchmartD eveloper Second prize is a DS08502 500MHz Digital Oscilloscope from Link Instruments and third prize is a Weller WD1002 Soldering Station from Cooper Tools Three honorable mentions will receive a Parallax Boe Bot All entrants who post a schematic will receive a 8 are not good at technology They are crap at technology You have to solve the prob lems kids are r
76. period PTPER PWM_PERIOD PWMCON1 0x0000 set PWMCON 2 for synchronized updates PWMCON2 0x0000 turn on PWM1L and PWM modulate PWM1H OVDCON 0x0201 set the initial duty cycle PDC1 0 turn PWM time base on PTCONbits PTEN 1 By configuring the MCPWM module and writing new values to the PDC1 duty cycle register we can vary the speed of the motor The next stage is to provide some feedback on how fast the motor is actually going so that we can more accurately con trol it and respond to changes in load We could provide this feedback as we did last month using signals from the opti cal interrupter However marketing wants a lower cost design without the interrupter and also would like the speed control smoother Strange how engineers are fre quently expected to do more with less Measurements and filtering Last month we mentioned a method of maintaining the motor s speed by measuring the back EM F produced while it is rotating To do this in practice we need to briefly stop the MCPWM module from generating a drive signal and ground one side of the motor At the same time we must isolate the other side of the motor and measure the volt age on the terminals Provided that the motor Is not overloaded it will continue to spin and the EMF across it will increase until it reach es a fixed value proportional to the RPM At this point the back EM F is measured and the PWM signal is restarted To
77. prototyping purpose electronic components Electronic Design From Concept To Completion b WWW Labcenter Electronics Limited center Jabcenter com Registered in England 4692454 Electranics E mail info labcenter com Tel 44 0 1756 753440 Fax 44 0 1756 752857 Registered Address 53 55 Main Street Grassington North Yorks UK BDe3 5AA
78. recent kits added to our range See website or join our email Newsletter for all the latest news EPE Ultrasonic Wind Speed Meter Solid state design j wind speed meter anemometer that uses ultrasonic tech f gt niques and has no moving parts and does not need calibrating It is intended for sports type activities such as track events sailing hang gliding kites and model aircraft flying to name but a few It can even be used to monitor conditions in your garden The probe is pointed in the direction from which the wind is blowing and the speed is dis played on an LCD display Li E P i REWWE FWI vwa Ps i Specifications e Units of display metres per second feet per second kilometres per hour and miles per hour e Resolution Nearest tenth ofa metre e Range Zero to SOmph approx Based on the project published in Everyday Practical Electronics Jan 2003 We have made a few minor design changes see web site for full details Power 9Vdc PP3 bat tery Main PCB 50x83mm Kit Order Code 3168KT 36 95 Audio DTMF Decoder and Display Detects DTMF tones via an onboard electret microphone or direct from the phone lines through an audio trans former The numbers are displayed on a 16 character single line display as they are received Up to 32 numbers can be displayed by scrolling the display left and right There is also a serial output for sending the detected tones to a PC via the serial po
79. shop on our UK web site at www epemag co uk or contact us for a list of Radio Bygones books Project Building amp Testing 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 methods including stripboard custom printed circuit boards plain matrix boards surface mount boards and wire wrapping finishing off and adding panel labels getting problem 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 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 Th
80. simply mechani cal electrical or software ideas Ideas must be the reader s own work and must not have been published or submitted for publication else where The circuits shown have NOT been proven by us Ingenuity Unlimited is open to ALL abilities but items for consideration in this col umn should be typed or word processed with a brief circuit description between 100 and 500 words maximum and include a full circuit dia gram showing all component values Please draw all circuit schematics as Clearly as possible Send your circuit ideas to Ingenuity Unlimited Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU We do not accept submissions for IU via email Your ideas could earn you some cash and a prize Atmospheric Charge Monitor Unlucky Strike ACH year more people are killed by lighting than by all other natural hazards except flash floods A large part of the danger is that humans are incapable through their five senses of receiving a timely warning of a possible strike Scientific studies have shown that by the time you hear the most distant rumble of thunder or see the most distant flash it may already be too late You may be well within range of the next lightning strike Lightning occurs where the electrical difference between the earth and the atmosphere rises high enough to overcome the insulating properties of the air Through monitoring the potential differ ence be
81. socket is inserted first The programmer is equipped with good quality turned pin types that should be hard wearing The programmer interfaces to the host PC via a USB 1 1 or USB 2 0 port and an ordinary A B cable is used It is therefore easy to use with practically any PC that is reasonably modern Power is normally supplied by a mains adapter so the unit should work perfectly well with the USB ports of laptop PCs or hubs that can provide only a limited amount of current It is possible to power the programmer from the USB port but with some limitations so it is better to opt for a mains adapter There are five ports that enable the programmer to connect to the outside world when it is being used as the basis of a pro totype design The connections to each port are made by way of a 9 pin female D connector and most E Blocks can be plugged 62 straight into the programmer avoiding the need for connecting cables Of course something less than the full set of five ports will be implemented when using most PIC microcontrollers Clocking on A reasonable range of clock options is pro vided A switch is used to select either a crys tal controlled clock or a simple C R type In the C R mode another switch provides the option of a fast or slow clock rate and there is also a preset resistor potentiometer that enables the clock frequency to be adjusted The programmer is fitted with a 19 6608M Hz crystal This is fitt
82. still come up with useful constructional articles worth repeating for others One should be able to see in one s head what processes are needed for things like switch debouncing it s only a delay tactic that s needed appreciate your comments but doubt that shall ever produce flow charts as a general rule Edward responded to me appreciate your prompt response EPE people are very good at responses cannot conceive of going straight to assembler or C from an idea in my head for output to i Windows attached printer including USB and networked printers www geocities com DO SPrint DOSPRINT is a small command line application that will read Epson dot matrix style ESC sequences from a file translate these into Windows printing calls and then send the printout to either the default printer or a printer of your choice It works very well out of the box in its default mode and also has a number of advanced options to allow you to fine tune the output The above web page also has details explaining how you can use DOSPRINT to a complex routine like a setup menu because it has so many branches and loops have done it for simpler routines that don t have lots of branches M aybe need more practice guess another issue is that even if an EPE reader who is a software novice succeeds in writing working code it may be unnecessarily large or slow think my menu will eventually work but it s going
83. the comment Make PORTD all output That s odd shouldn t the LEDs have come on We have pin pointed the offending line It s setting PORTB to outputs not PORTD Change the code to cirf TRISD Then quickbuild the program program the target processor and run the debugger again At last Three LEDs light up as expected OK it s a very trivial example and you would probably have worked out all the bugs by just reading the source code but it demonstrates a debugging technique that scales to larger problems problems that cannot be solved by reading pages and pages of source code The only drawback with hardware debuggers is that they need a few I O lines left unused in your design that are dedicated to the debugger inter face If your design is going to be compli cated it might be probably will be a price worth paying Assignment of variables Let s get back to the details of pro gramming in MPLAB You may be won dering how we handle the assignment of variables an issue we have ignored with our simple example program The answer is probably exactly the same as you have done in previous assemblers using the EQU directive to assign meaningful names called symbols to fixed absolute RAM locations Let s say you want to create a variable called size to hold some value You can create a symbol like this size EQU 0x23 There is no magic here the RAM loca tion 0x23 is not reserved in anyway to y
84. the filter definition which is in the automatically generated file PID control In the last part of our super motor mecha tronics demonstration we are going to intro duce some classical control We previously used a very simple algorithm that looked at the error in the measured RPM compared to the requested RPM A proportion of this Everyday Practical Electronics August 2007 Table 2 Sources Da yen Gwan iter me Godegen ni Where www microchip com 4 vs BEB mann Du EE ee aa T a i aaa EO MPLAB IDE Free MPLAB C30 Free Student Edition C30 and DSP Library 16 bit resources ET z e ne on ee ki 16Bit Fig 4 Filter design tool error signal was added to the control signal in an attempt to reduce the error signal to zero In essence we had created a simple P controller As part of the free DSP libraries supplied with Microchip s 16 bit compiler C30 there is a full PID implementation that can efficiently calculate a new output value in just 11 instruction cycles Rather than going into any in depth the ory on PID controllers let us just consider the different terms and how a value for each should be arrived at A digital PID controller is executed at a periodic sam pling interval and it must be assumed that the controller is executed frequently enough to properly control the system First an error signal is generated based upon the difference between the command ed value and the actual speed This
85. the internet and are very effective The early PIC processors didn t have fancy peripherals and we managed then How much effort you put into this process will depend on what your objec tives are If you are designing commercial products that will sell in their thousands then you are likely to be under pressure to use the cheapest smallest part possible If you are making a hobby project that will be a one off then your criteria may be com pletely different you may well want to use a PIC that is oversized and overpow ered simply because you have an existing development board and know how to use it Often though your needs will lay some where between the two extremes Low working voltage requirements come with another hazard While a datasheet may suggest a part operates at low voltages in many cases it is only spe cial variants of that part that support this These parts are designated by the letter L in the middle of the part name For exam ple the 16F 871 datasheet states it supports low voltage operation it takes further studying of the datasheet to reveal that this only applies to the 16LF871 part Simple enough to overlook and often the low volt age part is difficult to source from normal distri butors Circuit design Once you have chosen your PIC it s time to start designing your circuit The key point here is that you are assigning your I O requirements to specific I O pins This is very important
86. to be vastly less efficient than an expert would write can t see how one would learn efficient coding from EPE if it is purely teaching us how to code simple actions and leaving it to us to work out the overall structure of the program So still think there is need in EPE construc tional articles for more info on the soft ware structure a high level flow chart rather than a detailed one Keep up the good work could not get even as far as have without EPE Edward via email The sad truth is that expertise in efficient coding can really only come from years of experience and the ability to analyse mat ters down at their most basic levels l ve sometimes thought that have coded something efficiently only later to read someone else s code for a similar matter and find that it is far more efficient regret to say that there are some aspects to pro gramming that can never be taught But one can certainly learn from reading other people s code and seeing how they have tackled a similar situation As far as efficiency is concerned does it necessarily matter In many instances just the fact that it works correctly is good enough It doesn t matter that a particular routine may take 2ms to perform conpared to a possible lms especially if other rou tines take a long time anyway such as waiting for a user to press a switch Far more important is the fact that the author has got the code working correct L Other
87. using negative feedback provided by the 5 6kQ and 2 7kQ resistors The amplified signals from IC1a s pin 1 output are then fed to this chan nel s tone control stage which is based on IC2a half of a second TLO72 dual op amp IC2a is connected in what is known as a Baxandall negative feedback tone control circuit where Everyday Practical Electronics August 2007 the op amp s negative input is con nected to the wipers of both the Bass and Treble control pots VR2a and VR3a As shown the incoming signals from ICla are fed to one end of each pot s filter circuit while the feedback signals from IC2a s output pin 1 are connected to the other end of each filter circuit TwinTen Stereo Amplifier As a result when both VR2a and VR3a are set to the middle of their ranges the tone control stage provides the same gain ie unity or 1 for signals of all audio frequencies This gives the amplifier a flat frequency response However if VR2a is turned clockwise towards input preamp IC1a the stage provides more gain for frequencies SPECIFICATIONS Power Output Both channels driven into 8Q Both channels driven into 4Q One channel driven into 4Q IHF Burst Peak Output Music Power Both channels driven into 8Q Both channels driven into 4Q General Distortion at 1W continuous into 8Q Frequency response 3dB points 0 04 THD 10Hz to 72kHz Signal to noise ratio 10W RMS into 4Q Input impedance
88. work and product design Assuming no prior knowledge of microcontrollers and introducing the PICs capabilities through simple projects this book is ideal for use in schools and colleges It is the ideal introduction for students teachers technicians and electronics enthusiasts The step by step explanations Everyday Practical Electronics August 2007 make it ideal for self study too this is not a reference book you start work with the PIC straight away The revised third edition covers the popular repro grammable Flash PICs 16F54 16F84 as well as the 12F508 and 12F675 270 pages Order code NE36 18 50 FREE PROGRAMMING 16 BIT PIC CD ROM MICROCONTROLLERS IN C Learning to Fly the PIC24 Lucio Di Jasio Application Segments Manager Microchip USA A Microchip insider tells all on the newest most powerful PICs ever Focuses on examples and exercis es that show how to solve common real world design problems quickly Includes handy checklists to help readers perform the most common programming and debugging tasks FREE CD ROM includes source code in C the Microchip C30 compliler and MPLAB SIM software so that readers gain practical hands on programming experience Until recently PICs didn t have the speed and mem ory necessary for use in designs such as video and audio enabled devices All that has changed with the introduction of the first ever 16 bit PIC family the PIC24 This new guide teaches readers
89. 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 The author s tongue in cheek humour makes it a delight to read but this is a REAL technical book extremely detailed and accurate Comes with a free CD ROM which contains an eBook version with full text search plus bonus chapter An Illustrated History of Electronics and Computing Contents Fundamental concepts Analog versus digital Conductors and insulators Voltage current resistance capacitance and inductance Semiconductors Primitive logic functions Binary arith metic Boolean algebra Karnaugh maps State dia grams tables and machines Analog to digital and dig ital to analog Integrated circuits ICs Memory ICs Programmable ICs Application specific integrated cir cuits ASICs Circuit boards PWBs and DWBs Hybrids Multichip modules MCMs Alternative and future technologies Order code BEB1 27 50 BEBOP BYTES BACK and the Beboputer Computer 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 com puters work It picks up where Bebop left off guidi
90. 00 to December 2000 or www epemag com USA prices VOL 5 BACK ISSUES January 2001 to June 2001 or by phone Fax E mail or Post VOL 6 BACK ISSUES July 2001 to December 2001 VOL 7 BACK ISSUES January 2002 to June 2002 l VOL 8 BACK ISSUES July 2002 to December 2002 VOL 9 BACK ISSUES January 2003 to June 2003 l I I I I i BACK ISSUES CD ROM ORDER FORM Please send me the following Back Issue CD ROMs Volume VOL 10 BACK ISSUES July 2003 to December 2003 VOL 11 BACK ISSUES January 2004 to June 2004 VOL 12 BACK ISSUES July 2004 to December 2004 VOL 13 BACK ISSUES January 2005 to June 2005 E ee ae ain ee ee ene es VOL 14 BACK ISSUES July 2005 to December 2005 VOL 15 BACK ISSUES January 2006 to June 2006 l VOL 16 BACK ISSUES July 2006 to December 2006 NOTE These CD ROMs are suitable for use on any PC with a I CD ROM drive They require Adobe Acrobat Reader available free Adae from the Internet www adobe com acrobat l l l WHAT IS INCLUDED All volumes include the EPE Online editorial content of every listed issue plus all the available PIC Project Codes for the PIC projects JE Voy A A ke a Post Code l published in those issues Please note that we are unable to answer I technical queries or provide data on articles that are more than five H enclose cheque P O bank draft to the value of years old Please also ensure that all co
91. 1a and Sib select the input signals for the left and right channels as described previously while the third S1c pole is used to switch about 10mA DC to one of three LEDs to show which input source has been selected The LEDs have different colours so they re easily identified from a distance Construction The new amplifier is very easy to build with all components apart from the four loudspeaker terminals mount ing directly on a single PC board This board is coded 626 and measures 215 x 156mm It s designed to fit inside a low profile plastic instrument case measuring 225 x 165 x 40mm The box is fitted with a rear panel cut from 2mm thick sheet aluminium which acts as the heatsink for the two output amplifier ICs IC3 and IC4 However by itself the heatsinking pro vided by the rear panel is insufficient Therefore an external finned heatsink is bolted to the rear panel to help keep the power amplifier ICs cool 52 100 Fig 3 this plot shows how the noise and distortion THD varies with frequency for a power output of 1W into 8Q It s better than 0 05 from 20Hz to 20kHz As shown in the photos the front panel on the prototype was also made from aluminium but a standard plastic panel could also be used To reduce off board wiring to a minimum we have mounted input selector switch S1 directly on the PC board with its control spindle verti cal The only complication
92. 2 module Note the orientation of the flat cathode side which is shown facing JP1 on the overlay diagram Microcontroller firmware The necessary code to program the microcontroller RFID HEX is available from the download area of Fig 4 check your board against this full size etching pattern before installing the parts the EPE web site at www epemag co uk Initialising the module Before using the module the desired operating mode must be set and at least one ID programmed Let s see how this is achieved The operating mode is selected by installing a jumper shunt on JP1 and connecting a wire link between two terminals of CON2 Fig 5 shows which terminals to link for each of the four modes No link should be installed if Mode 1 operation is desired Once the link ifneeded and jumper are in place connect 12V DC to the power input terminals CON1 Be particularly careful that you have the positive and negative leads round the right way otherwise transistors Q2 and Q3 and perhaps diodes D2 and D3 will self destruct Assuming all is well the module will immediately beep to indicate the chosen mode For example witha link between the door strike output and the tamper switch input the module will beep four times to indicate that Mode 4 has been selected Fig 5 a temporary wire link must be inserted in the 4 way terminal block as part of the initialisation procedure in order to se
93. ARANCE catalogue send 1 00 in 1st or 2nd class stamps FOR COMBINED VALVE amp COMPONENT CLEARANCE list a a 50 in 1st yi 2nd class stamps W urcher 676 Foxhall Road Ipswich Suffolk 1P3 SNO Tel 01473 272218 ELECTRONIC COMPONENTS amp KITS P amp P still just 2 50 orders over 25 Free P amp P A wide range of popular components No Minimum Order No Sign up No VAT Visit our easy to use website www rshelectronics co uk BTEC ELECTRONICS TECHNICIAN TRAINING NATIONAL ELECTRONICS l VCE ADVANCED ICT vin HNC AND HND ELECTRONICS amp Text over composite video LOM FOUNDATION DEGREES Free toy sensors or buttons NVQ ENGINEERING AND IT TYV DESIGN AND TECHNOLOGY LONDON ELECTRONICS COLLEGE 20 PENYWERN ROAD N R BARDWELL Ltd est 1948 EARLS COURT LONDON SWS 9SU Electronic Component Supplies KWA CL kw ai LED s Semis IC s Resistors Caps etc A kk VE eae Tas send 44p for lists 1000 s bargains at our secure site www bardwells co uk 288 Abbeydale Rd Sheffield S7 1FL BOWOOD ELECTRONICS LTD 0845 166 2329 local rate Suppliers of Electronic Components Place a secure order on our website or call our sales line All major credit cards accepted Web www bowood electronics co uk aa i A Unit 1 McGregor s Way Turnoaks Business Park B om Li an an DA L Bann Chesterfield S40 2WB Sales 01246 200222 na Send 60p stamp for catalogue New Catalogue For Gadgets am
94. BH22 9AU Tel 01202 873872 Fax 01202 rable ka A on ad ie ked 874562 Email subsQepemag wimborne co uk Also via the vanpome Publ hingi Ete oedu ala mouse Web at http www epemag co uk Subscriptions start with the sek do A pote a next available issue We accept MasterCard Amex Diners Club E re oni b k Maestro or Visa For past issues see the Back Issues page mail subs epemag wimborne co u ONLINE SUBSCRIPTIONS Online subscriptions for downloading the magazine via the Internet 15 99US approx 9 00 for one year available from www epemag com USA CANADA SUBSCRIPTIONS enclose payment of cheque PO in sterling only payable to Everyday Practical Electronics My card number 18 Sere ee ee I Please print clearly and check that you have the number correct To subscribe to EPE from the USA or Canada please telephone Signature aea Sent ete etn tome mee aa eed brated SPA eee ee eats eat Express Mag toll free on 1877 363 1310 and have your credit K l card details ready Or fax 514 355 3332 or write to Express Mag Card Security Code The last 3 digits on or just under the PO Box 2769 Plattsburgh NY 12901 0239 or Express Mag SELIM n 8155 Larrey Street Anjou Quebec H1J 2L5 Email address expsmag expressmag com CardyEx Dalle snore aire mi no Maestro Issue No Web site www expressmag com USA price 60 US per annum Canada price 97 Can per annum 12 is
95. D ROMs above are Order form on next page Hobbyist Student Institutional Schools HE FE Industry Institutional Professional 10 user Network Licence Site Licence Flowcode 10 user Network Licence Flowcode 50 user Network Licence 45 inc VAT 99 plus VAT 300 plus VAT 599 plus VAT 350 plus VAT 699 plus VAT UK and EU customers add VAT at 17 5 to plus VAT prices Everyday Practical Electronics August 2007 35 SPECIAL PACKAGE OFFER TINA Pro V7 Basic Flowcode V3 Hobbyist Student TINA Analogue Digital Symbolic RF MCU and 50 00 Mixed Mode Circuit Simulation Testing and PCB Design m TINA Design Suite is a powerful yet affordable software package for analysing designing and real ee VAT and pap time testing analogue digital MCU and mixed electronic circuits and their PCB layouts You can also analyse RF communication optoelectronic circuits test and debug microcontroller applications Enter any circuit up to 100 nodes within minutes with TINA s easy to use schematic editor Enhance your schematics by adding text and graphics Choose components from the large library containing more than 10 000 manufacturer models Analyse your circuit through more than 20 different analysis modes or with 10 high tech virtual instruments Present your results in TINA s sophisticated diagram windows on virtual instruments or in the live interactive mode where you can even edit your circuit duri
96. EQUOIA HOUSE 398A RINGWOOD ROAD FERNDOWN DORSET BH22 9AU Orders are normally sent out within seven days of receipt but please allow 28 days for deliv ery 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 and CD ROMs see the next two issues of EPE Tel 01202 873872 Fax 01202 874562 Email dos epemag wimborne co uk Order from our online shop at www epemag co uk shopdoor htm BOOK CD ROM ORDER FORM Full Name ittit visit ak atak pal ok l kak al Post code Signature i sesccacsesjecastancenuesonssouniasndasaansarcomedanracnertage ET Telephone NO sssesssessesseseeseesesseeseressresseese l enclose cheque PO payable to DIRECT BOOK SERVICE for L Please charge my card Card Number Card Security Code Please send book CD ROM order codes The last 3 digits on or just below the signature strip 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 August 2007 71 PCB SERVICE Printed circuit boards for most recent EPE constructional projects are available from the PCB Service see list These are fabricated in glass fibre and are fully drilled and roller tinned Double sided boards are NOT plated through hole and will require vias
97. 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 constructor s 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 88 pages Order code BP299 5 49 DIGITAL LOGIC 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 mapping are explained demonstrated and used extensively and more attention is paid to the subject of synchronous coun ters than to the simple but less important ripple counters No background other than a basic knowledge of electron ics is assumed and the more theoretical topics are explained from the beginning as also are many working practices The book concludes with an explaination of microprocessor techniques as applied to digital logic Order code PC106 9 95 200 pages A BEGINNER S GUIDE TO TTL DIGITAL ICs R A
98. IO 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 comprehensive 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 proce dures jargon and setting up a station Technical topics covered include propagation receivers transmitters and aerials etc Order code BP257 5 49 150 pages 92 pages Computers and Computing THE INTERNET FOR THE OLDER GENERATION Jim Gatenby Especially written for the over 50s Uses only clear and easy to understand language Larger type size for easy reading Provides basic knowledge to give you confi dence to join the local computer class This book explains how to use your PC on the Internet and covers amongst other things Choosing and setting up your computer for the Internet Getting connected to the Internet Sending and receiving emails pho tographs etc so that you can keep in touch with fami ly and friends all over the world Searching for and sav ing information on any subject On line shopping and home banking Setting up your own simple web site Order code BP600 8 99 BUILD YOUR OWN PC Fourth Edition Morris Rosenthal More and more people are building their
99. Ingenuity Unlimited e Circuit Surgery e Practically Speaking e Techno Talk e PIC N Mix e Net Work The Internet Page APH HAMMAR ABT EER Tae Bi LAT JUN 07 PROJECTS e Bat Sonar e 3V to 9V Converter e A Poor Man s Q Meter Energy Meter Part 2 FEATURES e The Power of Mechatronics Part 1 Using MPLAB Part 1 e Circuit Surgery e Interface e PIC N Mix e Ingenuity Unlimited e Network The Internet Page e Techno Talk e Free Mechatronics CD ROM JULY 07 PROJECTS e Lead Acid Battery Zapper e Video Reading Aid Minical 5V Meter Calibration Standard e Digi Flash Slave FEATURES e Ingenuity Unlimited e Techno Talk e PIC N Mix e Using MPLAB Part 2 e Circuit Surgery e The Power of Mechatronics Part 2 e Practically Speaking e Net Work IF Armin thee bet BACK ISSUES ONLY 4 00 each inc UK p amp p Overseas prices 4 75 each surface mail 5 75 each airmail We can also supply issues from earlier years 2002 only Dec 2003 except June 2004 except June July Oct and Dec 2005 except Feb Nov Dec 2006 except Jan Feb Mar Apr and July Where we do not have an issue a photocopy of any one article or one partof a series can be provided at the same price ORDER FORM BACK ISSUES PHOTOCOPIES INDEXES L Send back issues dated LI Send photocopies of article title and issue date LI Send copies of last five years indexes 4 00 for fiv
100. J P2 TX used to speed our development and simpli fy complex filtering and control tasks 16 into 8 will go The PICDEM Mechatronics Demo board see part 1 is designed to accommodate var ious 8 bit PICs and it comes supplied with PIC16F917 PIC16F690 and PIC12F509 devices But with the careful use of a knife and a little bit of soldering it is quite possi ble to put a 16 Bit dsPIC30F4011 into the same socket In this section we will describe the required changes to the board and then we will go on to discuss the architecture of the device and how it can be used to drive our BDC motor Everyday Practical Electronics August 2007 It should be noted that M icrochip typ ically offers a lifetime warranty on its development tools but cutting the tracks on the board will void this While the modifications are simple do not carry them out if the loss of warranty concerns you Before we begin modifying the Demo board it will be necessary to obtain a dsPIC 30F 4011 301 P These can be purchased at low cost from any of the conventional sources although Microchip offers a free service that allows users to request samples of parts Go to sample microchip com and follow the registration prompts and request your free samples Armed with our new high speed processor we can get to work Looking at the pin outs of the PIC16F917 in datasheet DS41250 and the dsPIC30F4011 in datasheet DS70135 it can be seen that they are very similar
101. JR X Er aA 0 707V Vot The gain at the pole frequency is 0 707 or 3dB Fig 1 is alow pass filter and now we see that its pole frequently is at its cut off frequency In general at a pole fre quency the gain will con tinue to drop by 20dB per decade 6dB per octave more than at lower fre quencies Note that a decade is a 10 fold change in frequency and an octave is a halving or dou bling of frequency Fig 2 shows the typical frequen cy response characteris tics of a circuit with a sin gle pole Note the phase shift tends towards 902 and that that the graph uses a log frequency scale so decades will be evenly spaced on the frequency axis Fig 3 shows another simple RC circuit For this circuit the equation relating V out to V in in terms of the complex frequency s is following a similar approach to before fi KISE y LR R C _ __8 amp Cs 1__j R Cs R Cs 1 R Cs 1 Ano m R R Cs 1 A gain we want to get s on its own in the formula which gets a little untidy y RE s 1 R C R R C s 1 R R C From this we see that the circuit has a pole at i R R C This frequency response also has another critical feature Ats 1 R C the value of the formula is zero The value of 5 for which this occurs is called a zero of the circuit s response In general a circuit s response may have mul tiple poles and zeros For example if the circuit response was
102. L NIAL X y AN W o gt sail NA VOVSNI YA La lt O O AL SA VI INdNI JSN AYAN Ni OVAJ L ACL AZI y y b VOVSNI W001 va La JOL NAL OL JOZ 901 49089 JOL l ILJA IHON do uoz ASON Li ZZ q sl IZ ssyg IZ 19 S ENN 4UOL ZZOU ZI LOI ME MAN l I l l l l l MAN YOL JOLT 4d089 i Ne 4U0ZZ 901 1491 JOL O O caw DIYA ALE PIS op HI JINNL 51 Everyday Practical Electronics August 2007 AUDIO PRECISION SCFREQRE AMPL dBr vs FREQ Hz 10 000 8 0000 6 0000 4 0000 2 0000 AUDIO PRECISION SCTHD HZ THD N vs FREQ Hz 0 0 Fig 2 the frequency response curves for the left and right channels of the amplifier The response is 3dB down at 10Hz and 72kHz operate from the same high voltage rails because the signals they handle are at a much lower level IC1 and IC2 are there fore operated from 12V and 12V rails derived from one of each pair of high voltage rails using 470Q series resistors and 12V Zener diodes ZD1 and ZD2 There s also a 470uF capacitor across each Zener diode for added filtering and decoupling while the supply lines to IC1 are also given a small amount of extra decoupling via the 100Q resistors and 100nF capacitors Finally note that the selector switch has three poles Two of these S
103. LV 24 33 and experi ence all advantages of these microcontrollers dsPICPRO 3 Development Board Complete Hardware and Software solution with on board USB 2 0 programmer and mikrolCD The system supports dsPIC microcontrollers in 64 and 80 pins packages It is delivered with dsPIC30F6014A microcontroller dsPICPRO3 development system is a full featured development board for the Microchip dsPIC MCU dsPICPRO3 board allows microcontroller to be interfaced with external circuits and a broad range of peripheral devices This development board has an on board USB 2 0 programmer and integrated connectors for MMC SD memory cards 2 x RS232 port RS485 CAN on board ENC28J60 Ethernet Controller DAC etc BIGPIC4 Development Board Complete Hardware and Software solution with on board USB 2 0 programmer and mikrolCD Following tradition of its predecessor r BIGPIC3 as one of the best 80 pin PIC development systems on the market BIG PIC4 continues the tradition with more new features for the same price System supports the latest 64 and 80 pin PIC microcontrollers it is delivered with PIC18F8520 Many of these already made examples guarantee successful use of the system Ultra fast on board programmer and mikrolCD In cir cuit Debugger enables very efficient debugging and faster pro totype developing Examples in C BASIC and Pascal language are provided with the board BIGAVR Development Board with on board USB 2 0 p
104. Only a few power supply lines need to be connected and the two In Circuit Serial Programming ICSP pins need to be iso lated and changed Shown in Table 1 is a list of the connections that must be made on the PICDEM Mechatronics board and shown in Fig l is a diagram indicating where the wire links should be made As well as the links there is a permanent connection between PGD and the RS232 TX line driver To prevent problems when programming this track must be cut just above pin 1 of the dsPIC DSC as indicat ed in Fig l The dsPIC DSP part has its ICSP pins in a different location to those of the PIC16F917 and has instead voltage rails for the internal analogue peripherals on the same pins For powering the device pins 39 and 40 must be carefully bent out so that they do not fit into the socket and then wire connections must be soldered from the pins on to the nearby V 4 and V terminals W ith these changes in place we can now connect up our MPLAB ICD2 programmer and we will be able to communicate with the computational efficiency and throughput of a Digital Signal Processor or DSP The dsPIC30F is part of Microchip s family of 16 bit devices that can be used in high performance applications and can even operate in what might be considered a 32 bit only application Rather than depart ing completely from the PIC heritage the devices were designed to provide a look and feel that 8 bit PIC engineers would find familiar
105. PIC N MIX e Net Work The Internet Page PROJECTS e Loudspeaker Level Meter e Telephone Dialler for Burglar Alarms Adjustable DC DC Converter for Cars High Intensity Torch FEATURES e Circuit Surgery e Techno Talk e Teach In 2006 Part 10 e PIC N Mix e Interface e Ingenuity Unlimited e Net Work The Internet Page ETEF APA bee T ETIE II il MI SEPT 06 PROJECTS e Low Cost 50 MHz Frequency Meter e Smart Mixture Display for Your Car e Human Powered LED Torches e Water Level Gauge FEATURES e Teach In 2006 Part 11 e Ingenuity Unlimited e Circuit Surgery e Techno Talk e PIC N Mix e Practically Speaking e Net Work The Internet Page OCT 06 PROJECTS e Studio 350 Power Amplifier Part 1 e Fridge Door Open Alarm e Through Glass Alarm e Linear Supply for 1W Star LEDs FEATURES e Ingenuity Unlimited e Circuit Surgery e Techno Talk e PIC N Mix e Interface e Net Work The Internet Page NOV 06 PROJECTS e Giant LED Message Display e Micropower Battery Protector Quick Brake Studio 350 Power Amplifier Part 2 FEATURES e C For PICs Part 1 e Ingenuity Unlimited e Circuit Surgery e Techno Talk e PIC N Mix e Practically Speaking e Net Work The Internet Page 46 DEC 06 PROJECTS e USB Power Injector e RGB To Component Video Converter Lapel Microphone Adaptor For PA Systems e Mind Trainer FEATURES e C For PICs Part 2 e Circuit Surgery e Interface e
106. PLICATIONS Third Edition Mike Tooley A comprehensive reference text and practical electronics handbook in one volume at an affordable price New chapter on PIC microcontrollers the most popular chip family for use in project work by hobbyists and in colleges and universities New companion website spreadsheet design tools to simplify circuit calculations circuit models and templates to enable virtual simulation a bank of on line questions for lecturers to set as assignments and on line self test multiple choice questions for each chapter with automatic marking to enable students to continually monitor their progress and understanding The book s content is matched to the latest pre degree level courses making this an invaluable reference for all study levels and its broad coverage is combined with practical case studies based in real world engineering contexts throughout the text The unique combination of a comprehensive reference text incorporating a primary focus on practical applica tions ensures this text will prove a vital guide for stu dents and also for industry based engineers who are either new to the field of electronics or who wish to refresh their knowledge 400 pages BEBOP TO THE BOOLEAN BOOGIE Order code NE43 24 95 Second Edition BOOK PLUS Clive Max Maxfield CD ROM This book gives the big picture of digital electronics This indepth highly readable up to the minute guide shows
107. 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 MICROCONTROLLER COOKBOOK Mike James The practical solutions to real problems shown in this cook book provide the basis to make PIC and 8051 devices real ly work Capabilities of the variants are examined and ways to enhance these are shown A survey of common interface devices and a description of programming models lead on to a section on development techniques The cookbook offers an introduction that will allow any user novice or experienced to make the most of micro controllers 240 pages 23 50 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 Jonathan Hill s excellent Radio Radio a comprehensive book with hundreds of photos depicting the development of the British wireless set up to the late 1960s The four 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 and clandestine equip ment from pre war through to the 1960s For details see the
108. RONICS TECHNOLOGY amp COMPUTER PROJECTS See notes on Readers Technical Enquiries below we regret technical enquiries cannot be answered over the telephone Advertisement Offices EVERYDAY PRACTICAL ELECTRONICS ADVERTISEMENTS Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU VOL 36 No 8 AUGUST 2007 Complexity Sometimes can t help thinking that while microcontrollers simplify circuits allow easier modification and updating of circuit operation and give designers the ability to provide complex logic functions easily that they also allow over complex operation M any modern washing machines now have a whole host of programmes temperatures water saving settings etc how many of them are ever used The same goes for things like burglar alarms our new offices please note our new address opposite have just been fitted with anew alarm system microcontroller controlled of course We have a similar sys tem at home fitted only a year or so ago Obviously the technology used has moved on in that year and the new system took the engineer over an hour to program simply because all the functions inputs outputs timers etc are now fully programmable The new unit also has a 250 event memory will support up to four remote keypads which can be wired star or daisy configuration has four access level codes which are all programmable etc etc The Engineer s M anual carries nearly 30 pages of programming information
109. SP116 3 x 10mm Green LEDs SP192 3 x CMOS 4066 SP118 2 x CMOS 4047 SP195 3 x 10mm Yellow LEDs SP124 20 x Assorted ceramic disc caps SP197 6 x 20 pin DIL sockets SP126 6 x Battery clips 3 ea SP198 5 x 24 pin DIL sockets PP3 PP9 SP199 5 x 2 5mm mono jack plugs SP130 100 x Mixed 0 5W C F resistors SP200 5 x 2 5mm mono jack sockets SP131 2 x TLO71 Op Amps SP133 20 x 1N4004 diodes RESISTOR PACKS C Film 5 each value total 365 0 25W 3 40 10 each value total 730 0 25W 4 65 1000 popular values 0 25W 6 60 5 each value total 345 0 5W 4 30 10 each value total 690 0 5W 6 95 1000 popular values 0 5W 8 95 PCIB POOIE SERVICING YOUR COMP ROTOTYPE NEEDS 1 EUROCARD 160 x 100 mm Tooling Photoplots VAT ice example a ny size and contour possi Optional e Soldermask e Fast turnaround e Silkscreen e 4 Layer Multilayer e 6 Layer Multilayer DOWNLOAD OF EE LAVANT SOFTWARE Tel 353 0 Fax 353 0 619 pcb pool betg co GEE gf MAN OEM ee MM A Earn DAN PCB POOL COM 41 The Power of Mechatronics Part Three Stepping up a Gear by Darren Wenn series we applied some electronics to the control of a brushed DC BDC motor By controlling the motor from a PIC we were able to vary its speed and then apply software algorithms that improved the motor s response when running at low speed or under load So now that we are well on our way to ae earning our first m
110. THENOMTUK MAGATINE FOR ELECTRONICS TECHNOLOGY COMPUTER PROJECTS aaa EVERYDAY PRACTICAL pd ECTRONICS WII GVEA SW Wit WWW e Weil ag yc om O Marra Q Spe ra mAna y Q Fu On ScreenlControl a Q Q 3 eklate ele it i PRINTER HARDWARE EIR OU i 25274 rangs RAT ST RITY MODULF NE FE Copyright 2007 Wimborne Publishing Ltd 408 Wimborne Road East Ferndown Dorset BH22 9ND UK and TechBites 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 TechBites 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 TechBites Interactive Inc and Wimborne Publishing Ltd have used their best efforts in preparing these materials and works However TechBites 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 mer
111. Virtual Laboratories 8 Little previous knowledge required Mathematics is kept to a minimum and all calculations are explained e Clear circuit simulations Hobbyist Student s LES inc VAT _ Institutional Schools HE FE Industry 0 99 plus VAT Prices for each of the CD ROMs above are Institutional 10 user Network Licence 249 plus VAT Order form on third page Site LICENCE 0 aaa eara rar rranaaannananana annan an aannnannnannnnnnnnna 499 plus VAT UK and EU customers add VAT at 17 5 to plus VAT prices 34 Everyday Practical Electronics August 2007 PRICES PiCmicro TUTORIALS AND PROGRAMMING VERSION 3 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 from the 12 16 and 18 series PlCmicro ranges 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 OQ Makes it easier to develop PICmicro projects Supports low cost Flash programmable PICmicro devices O Fully featured integrated displays 16 individual l e d s quad 7 segment display and alphanumeric l c d display HARDWARE Supports PICmic
112. XT ols SK1 SERIAL FEMALE NC NC BAUD RESET A n E a ey aN REAR VIEW OF PINS 5 Ain 137 16mm 2 9in 73 66mm Everyday Practical Electronics August 2007 as convenient BNC sockets were used for SK2 and SK3 to suit the author s existing oscilloscope probes The case used in the prototype was sim ply one that was to hand and previously used in another application Perhaps a slimline case that will house the PCBs side by side might be visually preferable Drill holes in it to suit the connectors cho sen including one for an external power supply input if required Thoroughly check the assembled boards for good soldering and correct component positioning Then connect the 9V supply and check the correct voltages as shown in Fig 5 are present When all is well switch off and insert the DIL ICs after which check that the correct voltages are still present when power is reapplied Next month we run the software and outline the various functions DATA IN Fig 7 Component and track layout details for the analogue interface PCB Everyday Practical Electronics August 2007 The author s two early prototype circuit boards that make up the V2 PC Scope project Some minor changes have been made to the final PCBs Ler i ie rae AH i i je OUT CHAN 1 OV CHAN 1 SK2 OUT CHAN 2 OV CHAN 2 SK3 17 j y i ki i
113. YO pin 2 as an AC signal passing through capacitor C5 This allows the choice of DC or AC signal being output by pin Y to dual digital potentiometer chip IC8 This device was described in greater detail in PIC N Mix Sep Oct 05 Two possible configurations are shown in Fig 3 Its first role is to set the effective gain of op amp IC7b The resistance ratio of its two digit ally controlled resistors is controlled by data supplied by the PC and PIC via IC5 C6 22u 5V Mn 13 11 Ka 3 Eee fae Fig 2 Circuit diagram for the dual analogue input interface Its second role is that of controlling the bias voltage level applied to IC7b s non inverting input pin 5 It too is controlled by data sent via IC5 Thus between them IC6 and IC7b allow the signal gain and its DC level bias to be remotely controlled without the need for physical potentiometers Channel 2 is identical to Channel 1 apart from the change of component ID and pin numbers PIC to PC interface Data communication between the PC and controlling PIC is via a standard RS232 interface link through ports COM1 or COM2 at one of several Baud rates as selected by the user namely 9600 19200 38400 57600 or 115200 Note that some PCs will not allow the use of all higher Baud rates but all will allow for 9600 Baud to be used The choice of Baud rate is made through the PC screen and auto matically communicated to the PIC which sets its controls a
114. a Its height is of some importance since atmos pheric charge varies with height Everyday Practical Electronics August 2007 Directly beneath the antenna at the ground a section of the microphone cable s screen is exposed showing through the insulation and is securely connected to a metal stake in the ground This metal stake is hammered half a metre 18in or so into the ground For safety purposes the remaining length of microphone cable several metres yards is buried in the ground and its far end taken to the circuit G etting going Attach the circuit to a suitable DC power supply between 7V and 30V Turn preset VR1 across its entire range until a point is reached where the meter needle moves boldly across the dial At this point care fully adjust V R1 so that the needle stands at the middle of the dial This adjustment is best made in dry weather since wet weather may yield misleading readings There is usually a trade off with circuits which are as simple as this In this case the needle falls as a thunderstorm approaches it would seem more intuitive for it to rise Another is that there is limited control over calibration In use you will notice daily variations of charge If the meter needle tends to drift too high or too low during the course of a day you may need to further adjust V R 1 to compensate When a_ thunderstorm approaches there should be a very obvious drop of the needle
115. acker RACAL DANA 9343M LCR Databridge Digital Auto Measurements of RCL QD RACAL 9008 Automatic Modulation Meter POWER SUPPLIES FARNELL AP60 50 0 60V 0 50A 1KW Switch Mode FARNELL H60 250 60V 0 25A THURLBY PL320QMD 0 30V 0 2A Twice Digital H P 6626A Precision High Resolution 4 Outputs 0 7V 0 15MA or 0 50V 0 0 5A Twice 0 16V 0 0 2A or 0 50V 0 2A Twice FARNELL XA35 2T 0 35V 0 2A Twice Digital FARNELL B30 1030V 10A Variable No Meters THURLBY PL3200 30V 0 2A Digitial TAKASAGO GM035 2 0 35V 0 2A 2 Meters Used Equipment GUARANTEED Most Manuals supplied Please check availability before ordering or calling Prices plus carriage and VAT 59 INTERFACE Robert Penfold PROBLEMS OF SETTING PARALLEL PORT OUTPUTS TO INPUTS HEN a circuit featured in Interface requires a number of inputs the solution that is usually adopted is to use the data lines of a printer port These lines are all set as outputs by default but as explained in a number of previous Interface articles with any reasonably modern PC they are easily set to operate as inputs Itis just a matter of setting bit 5 of the Control Register to 1 or to write a value of 32 to the relevant output address In other words the data lines are at the base address which is usually amp H 378 and the control register is two addresses higher With a base address of amp H 378 this places the Control Register at address GH37A Bear in mind that there are four
116. ady Has anything else changed apart from the relative costs of copper and silica Y ou bet American firm JDS Uniphase has just announced that the efficiency of light to power conversion has crossed the 50 per cent threshold In this way power hungry electronics can be fed over fibre as well as allowing electronics in remote hostile or inaccessible locations to be powered by fibre over longer distances T he technology is particularly handy for cost effective powering of electronics that operates in sit uations involving high voltages strong magnetic fields or radio frequency emissions The converter is designed on a gallium arsenide solar cell which transforms laser light into a DC voltage A 5W light source can deliver 1W of power at the remote sen sor and systems can be paralleled to generate 5W at the far end More advanced systems could deliver up to a kilowatt States DS Uniphase T his efficiency of 50 per cent pushes the boundaries of the maximum theoretical limit for photovoltaic power conversion This improvement enables more power hungry electronics such as transducers transceivers and sensors to be powered over fibre The higher power effi ciency also permits remote electronics to be powered by fibre over longer distances such as tower mounted installations for cellular and digital TV relay stations Sensory delight Light powered telephones and other forms of high power delivery over optical systems a
117. aising When asked if he had any ballpark fig ures from his time at Orange on how many people actually used fancy phone features like picture messaging emailing Bluetooth web access and so on he answered No don t have any figures But can reply anecdotally People hardly use a lot of the features we give them The services are too expensive They are too involved and difficult to set up Picture messaging takes six or seven clicks Of course I d probably say differently if were still employed by Orange The industry gave people features that were expensive and cumbersome We were extremely lazy and driven by the technolo gy We built in features that were fictitious We were dreaming People found other means of messaging They use peer to peer which Is free rather than contributing to the SchmartBoard T shirt and free SchmartBoards to build their circuit Winners will be announced in Jan 08 Details and entry form can be found at www schmartboard com SchmartB oard is committed to helping engineers students and hobbyists develop electronic circuits faster easier and less expensively than previously possible SchmartB oard s patent pending Electronic Circuit Building Blocks makes this possi ble SchmartBoard s EZ Technology makes the soldering of surface mount com ponents accessible to virtually anyone EPT Free Download A new version of Electronics M echanics M aths and Computing V 9 2 is
118. akers which open in a new photo 3D window Your map location is depicted with a moveable 3D human icon that also has a pointer so you can simply turn it with the mouse and trav el down the road make another turn and zoom in as if driving around in acar In fact thatis exactly how the imagery is generated the cam eras are fitted onto a fleet of blacked out MPVs that are trundling around major US cities and also said to be rolling out across Europe dialled in the address of B amp H Photo s store on Ninth Avenue and there it was large as life captured on a still camera The imaging technology behind Street View is impressive The 3D photography is shot via unique 11 lens Dodeca high resolution hard drive cameras with Immersive Technology s Telemmersion system www immersivemedia com Eleven rolling image streams and five sound channels are seamlessly stitched together into one image using software that creates a rolling 3D perspective An emerging online sport is that of finding in Street View some examples of people or situations that are erm unsavoury private or even humorous see topstreetviews com Guys have been pictured walking into adult stores and someone recognised their own cat The Google vans have been spotted as reflections in shop windows as well Street View could well turn into a voyeur s paradise and that s the problem Rather like the publication of military aerial views in Google Maps one cannot
119. al Geiger Counter double sided IR Remote Checker MAR 07 SMS Controller Lap Counter For Swimming Pools PIC Polyphonium Main Board PIC Polyphonium LED Display Interface APR 07 Students Amp Amplifier PSU Star Power Bass Extender MAY 07 Caravan Lights Check x Energy Meter Main Board JUN 07 Display Board ali 3V to 9V Converter PCB plus TL499A IC 620 chip Bat Sonar MiniCal 5V Meter Calibration Standard JUL 07 Lead Acid Battery Zapper Video Reading Aid Digi Flash Slave TwinTen Stereo Amplifier AUG 07 Printer Port Hardware Simulator RFID Security Module V2 PC Scope Control Board Analogue Board EPE SOFTWARE All software programs for EPE Projects marked with an asterisk and others previously published can be downloaded free from our Downloads site accessible via our home page at www epemag co uk PCB MASTERS PCB masters for boards published from the March 06 issue onwards can also be downloaded from our UK website www epemag co uk go to the Downloads section EPE PRINTED CIRCUIT BOARD SERVICE Order Code Project Quantity Price cheque PO in sterling only to Everyday op Practical Electronics a MasterCard Amex Diners pez Club Visa or Switch Maestro Card No Valid From Card Security Code Maestro Issue No The last 3 digits on or just under the signature strip Expiry Date Signature NOTE You
120. al only system as are the optical fibre local distribution networks that bring cable television broadband and telephony to the green cabinet at the end of your street or in afew cases right into the home In both situations a separate mains power supply is required to power user devices net work adapter cards in PCs TV set top boxes cable modems and so on And if there s a mains outage you re stuck whereas the exchange battery can keep traditional tele phone networks going when the mains fails Short term shortcoming Engineers and scientists love a challenge and endeavour to make sure that shortcom ings like this are short lived What s more they have come up with solutions to both of these setbacks Let s deal with ethernet first Power over ethernet PoE for short is the answer to the first problem and it s not quite a brand new invention if am to be com pletely candid Nevertheless the technology has by no means become commonplace or widespread despite its availability for a few years PoE is still viewed as a niche technology according to principal analyst M arianne D A quila of US technology analysis compa ny Information Resources In a recent survey by the firm potential users cited dissatisfac tion with the current technology combined with elusive cost and return on investment benefits as barriers to PoE reaching main stream status rapidly It s clever stuff even so and usage is fore cast to continue gr
121. all channels Treble tone control range at 2OkHz Bass tone control range at 50Hz 12kQ 600pF 11dB 12dB 12dB 13dB 49 Paris List iwinlen Ampliiier 1 PC board code 626 available from the EPE PCB Service size 215 x 156mm 1 low profile ABS instrument case 225 x 165 x 40mm 1 16V AC 1 25A plugpack 1 3 pole 3 4 position rotary switch 2 M205 PC mount fuse clips 1 M205 2A slow blow fuse 1 finned heatsink 84 x 24mm 3 PC mount dual RCA phono sockets 1 PC mount 2 5mm concentric power socket 4 binding posts 2 red amp 2 black 5 20mm skirted instrument knobs 1 knob actuator 40 x 30 x 2 5mm see text 4 6G x 6mm self tapping screws 3 6G x 9mm self tapping screws 2 M3 x 16mm screws nuts amp flat washers 2 TO 220 insulating washers and nylon bush sets 1 small tube of heatsink compound 1 300mm length of 0 7mm tinned copper wire 1 200mm length figure 8 speaker cable Semiconductors 2 TLO72 dual op amps IC1 1C2 2 LM1875T audio amplifiers IC3 IC4 2 12V 1W Zener diodes ZD1 ZD2 1 3mm green LED LED1 lower than about 500Hz thus giving bass boost On the other hand if VR2a is turned anticlockwise towards the out put of IC2a the stage provides lower gain for frequencies below 500Hz thereby giving bass cut In the same way VR3acan be used to give a variable amount of boost or cut to frequencies above 2kHz ie treble boost or cut And as both of these tone controls are part of
122. alling the four binding posts used for the loudspeaker terminals red to the top black to the bottom then slide the rear panel into position in the bottom half of the case That done slip the front panel over the pot shafts LEDs and switch actuator and slide this assembly into the case The PC board can now be tempo rarily secured by installing four 6G x 6mm screws at the corner positions Follow this by fastening the three dual RCA phono connectors to the rear fableyaResistomGolourGodes 4 Band Code 1 red violet yellow brown grey red orange brown green blue orange brown red violet orange brown brown black orange brown green blue red brown yellow violet red brown red violet red brown brown black red brown yellow violet brown brown brown black brown brown brown black black brown red violet gold brown pre MNN NO RARA NS A ONH Hftn 5 Band Code 1 red violet black orange brown grey red black red brown green blue black red brown red violet black red brown brown black black red brown green blue black brown brown yellow violet black brown brown red violet black brown brown brown black black brown brown yellow violet black black brown brown black black black brown brown black black gold brown red violet black silver brown Ee EE eee Ene 56 Everyday Practical Electronics August 2007 Above and right these two close up views clearly show the construction of the side actuator knob Note that
123. an then come back at a later date to your source code and do a Search for the word TODO to find unfinished parts of code This is such a useful feature that 30 rumour has it Microsoft have a patent on the idea Hardware debugger But digress back to the example code from last month with its elusive bug We ironed out syntax errors using the mes Sages generated by the assembler program then used the simulator to find some of the logical errors still lurking within the code Simulators however can never get close to the full reality of running code on real hardware The real problems those that keep you up in late night debugging ses sions can only be found on real hardware Debugging directly on hardware can be very difficult however since you cannot see registers change at each line of code executed The solution to this is to use a hardware debugger a small piece of hard ware that allows you to debug your code line by line on your own circuit board For the PIC there are several hardware debuggers available some at quite modest costs M icrochip not only produce a number of products they also make the designs freely available so you could even build your own We covered one such low cost product the PICK it2 in a previous article so we will use it here again to help solve the final bug The following section assumes you have access to a PICKit2 but if you don t read on anyway it may entice you to buy
124. and finally a 10 bit ADC that can operate at up to 1 MSPS In asimilar way to the ECCP module on the PIC16F 690 the MCPWM module can be configured to control a half or full bridge driver In our case we will connect the BDC motor between the Drive 1 and Drive 2 terminals and then control its speed by pulse width modulating the high side FET in the half bridge By using the MCPWM module high speed control can be automatically achieved with no soft ware Intervention Shown in Listing 1 are the instructions necessary to configure the MCPWM mod ule to control our motor Of particular interest is the OVDCON special function register SFR which allows us to control which PWM pins are being used by the module whether they are being PWM modulated and what state they should bein if not PWM modulated In this case by set ting OVDCON 0x0201 we are perma nently turning the low side of the bridge on and then modulating the high side 110 Ports AG Input Capture a anj Leon pate tte PWA B8 aki O e Timem I bit KPIS ti SPI Z UART 1 UART 2 iom Codec interface PS f ACH non ranni An fECANRN RA Aminn up lo I CAN f LLANZ 220b bytea Muto Controt A Ouand Fnr interface 1Z2 bit AMO 10 i Aar Fig 2 Simplified diagram of the dsPIC architecture Everyday Practical Electronics August 2007 43 Listing 1 void InitPWM void ensure the module is turned off PTCON 0x0000 set the timebase
125. anding variety of products designed for engineers hobbyists and students These include e ARM Development Systems e Ethernet Modules e RF Modules e Graphic LCD Displays With example software e Home Automation e Power Conversion e Components amp Connectors e And Much More Full product support with reference software and secure online ordering to kickstart your development www componentbin com 44 0 1354 778224 tel 01298 70012 fax 01298 70046 A www peakelec co uk ate A sales peakelec co uk electronic design ltd i i Handheld lest Gcar Cool Smart Atlas be SUTTER CHET UIC Ler AA by Se Pp Paar cp a Vila ECR NS Oo ME Pa R ee ee e i THA rs ATE Everyday Practical Electronics August 2007 SHERWOOD ELECTRONICS Buy 10 x 1 Special Packs and choose another one FREE SP1 15 x 5mm Red LEDs SP134 15 x 1N4007 diodes SP2 12 x 5mm Green LEDs SP135 5 x Miniature slide switches SP3 12 x 5mm Yellow LEDs SP136 3 x BFY50 transistors SP5 25 x 5mm 1 part LED clips SP137 4 x W005 1 5A bridge rectifiers SP6 15 x 3mm Red LEDs SP138 20 x 2 2 63V radial elect caps SP7 12 x 3mm Green LEDs SP142 2 x CMOS 4017 SP8 10 x 3mm Yellow LEDs SP143 5 Pairs min crocodile clips SP9 25 x 3mm 1 part LED clips Red amp Black SP10 100 x 1N4148 diodes SP144 5 Pairs min crocodile clips SP11 30 x 1N4001 diodes assorted colours SP12 30 x 1N4002 diodes SP146 10 x 2N3704 transistors SP18 20 x BC182B tr
126. anges e Max amp min RPM adjustment e Optional knock sensing e Optional coil driver Hand Controller Ignition Coil Driver all electronic components Add this ignition coil driver to the KC 5442 Programmable Ignition System and you have a complete stand alone ignition system that will trigger from a range of sources including points Hall Effect sensors optical sensors or the 5 volt signal from the car s ECU Kit supplied with PCB with overlay diecast case and D Knock Sensor This LCD hand controller is required during the initial set up procedure It plugs into the main unit and can be used while the engine is either running or stopped Using this Hand Controller you can set all the initial parameters and also program the ignition advance retard curve Kit supplied with silk screened and machined case PCB LCD and all electronic components Add this option to your KC 5442 Programmable High Energy Ignition system and the unit will automatically retard the ignition timing if knocking is detected Ideal for high performance cars running high octane fuel Requires a knock sensor which is cheaply available from most auto parts recyclers Kit supplied with PCB and all electronic components www jaycarelectronics co uk Everyday Practical Electronics Magazine has been publishing a series of popular kits by the acclaimed Silicon Chip Magazine Australia These projects are bullet proof and already tested dow
127. anley Virtually there Last month highlighted the increasing popularity of online shop ping especially sourcing goods from the USA where sterling dollar exchange rates continue to be favourable This month visit the USA again to take a stroll past the B amp H photo store on Ninth Avenue N ew York only l Il do it virtually using Google s incredible new 3D street level mapping service called Street View As many Internet users will know Google has built on its remark ably scalable processing power to introduce many more data related services Their free GM ail webmail service provides so much storage that running out of mailbox space is no longer a worry However their ability to read your emails and place contextual adverts next to them raised privacy concerns as did the fact that deleted emails could still be stored somewhere for a time No one likes the feeling that their emails are being read Google Maps maps google co uk com allows you to search for a place or postcode almost anywhere in the world from K abul to the Kremlin or view aroad map and overlay a satellite image a high resolution photo is available in some areas Even real time traffic data is being incorporated and can view the rush hour hot spots in New York this breakfast time Google s naivety in pub lishing detailed worldwide maps and satellite photos made this information useful to those who would wish the Western hemi sphere a
128. annel 1kHz to IMHz pattern generator with tabular waveform formatting or direct timing chart plotting on the screen e Square wave PWM pulse width modulation generator Compatible with Microsoft Windows ME 2000 and XP PoScope is supplied with easy to use software and a USB cable Oscilloscope probes and logic analyser test lead clip sets are available separately Order now on Freefone 08006122135 FRANL TTRROMi cC or online at www paltronix com EQUIPMENT FOR ELECTRONICS DEVELOPMENT TRAINING amp EXPERIMENTATION wb eita VISA Electro AIl major credit and debit cards accepted TIME FOR A CHANGE NEW Redesigned User Interface includes modeless NEW Simulation Advisor includes reporting on selection modeless wiring and intuitive operation to simulation problems with links to detailed maximise speed and ease of use troubleshooting information where appropriate NEW Design Explorer provides easy navigation NEW Trace capability within both MCU and design inspection tools and cross probing support to peripheral models provides detailed information on improve quality assurance and assist with fault system operation which allows for faster debugging finding of both hardware and software problems NEW 3D Visualisation Engine provides the means to NEW Hundreds of new device models including preview boards in the context of a mechanical design PIC24 LPC2000 network controllers and general prior to physical
129. ansistor In 1 addition the circuit also banishes Yi those annoying thumps that occur when many amplifiers are switched on or off especially when the volume is set to a high level The design also incorporates an optional over temperature heat sensor that will disconnect the speakers if the output stage gets too hot Configurable for supply voltages between 22VDC 70VDC Supplied with a silk screened PCB relay and all electronic components Stereo VU and Peak Meter Kit Accurately monitor audio signals to prevent signal clipping and ensure optimum recording levels This unit is very responsive and uses two 16 segment bargraphs to display signal levels and transient peaks in real time There are a number of display options to select and both the signal threshold and signal level calibration for each segment are adjustable Kit supplied with PCBs LCD and all electronic components Accuracy within 1dB for signals above 40aB e Case not included use ki HB 6082 i 2 95 gi l i POST AND PACKING CHARGES Order Value Cost Order Value Cost 20 49 99 5 200 499 99 30 50 99 99 10 500 40 100 199 99 20 Max weight 12lb 5kg Heavier parcels POA Minimum order 20 Note Products are despatched from Australia so local customs duty and taxes may apply How to order Phone Call Australian Eastern Standard Time Mon Fri on 0800 032 7241 Email Post PO BOX 6424 Silverwater
130. ansistors SP147 5 x Stripboard 9 strips x SP20 20 x BC184B transistors 25 holes SP23 20 x BC549B transistors SP151 4 x 8mm Red LEDs SP24 4 x CMOS 4001 SP152 4 x 8mm Green LEDs SP25 4 x 555 timers SP153 4 x 8mm Yellow LEDs SP26 4 x 741 Op Amps SP154 15 x BC548B transistors SP28 4 x CMOS 4011 SP156 3 x Stripboard 14 strips x SP29 3 x CMOS 4013 27 holes SP33 4 x CMOS 4081 SP160 10 x 2N3904 transistors SP34 20 x 1N914 diodes SP161 10 x 2N3906 transistors SP36 25 x 10 25V radial elect caps SP164 2 x C106D thyristors SP37 12 x 100 35V radial elect caps SP165 2 x LF351 Op Amps SP38 15 x 47 25V radial elect caps SP166 20 x 1N4003 diodes SP39 10 x 470 16V radial elect caps SP167 5 x BC107 transistors SP40 15 x BC237 transistors SP168 5 x BC108 transistors SP41 20 x Mixed transistors SP171 8 Metres 18SWG solder SP42 200 x Mixed 0 25W C F resistors SP172 4 x Standard slide switches SP47 5 x Min PB switches SP173 10 x 220 25V radial elect caps SP49 4 x 5 metres stranded core wire SP174 20 x 22 25V radial elect caps SP101 8 Metres 22SWG solder SP175 20 x 1 63V radial elect caps SP102 20 x 8 pin DIL sockets SP177 10 x 1A 20mm quick blow fuses SP103 15 x 14 pin DIL sockets SP178 10 x 2A 20mm quick blow fuses SP104 15 x 16 pin DIL sockets SP181 5 x Phono plugs asstd colours SP109 15 x BC557B transistors SP182 20 x 4 7 63V radial elect caps SP112 4 x CMOS 4093 SP183 20 x BC547B transistors SP115 3 x 10mm Red LEDs SP189 4 x 5 metres solid core wire
131. ard with on board USB 2 0 programmer The system supports 8 20 28 and 40 pin microcontrollers it comes with ATMEGA16 Each jumper element and pin is clearly marked on the board It is possible to test most of industrial needs on the system temperature controllers counters timers etc EasyAVR4 is an easy to use Atmel AVR development system On board USB 2 0 programmer makes your development easy Examples in BASIC and Pascal lan guage are provided with the board Easy8051A Development Board with on board USB 2 0 programmer Emi oi l cs mer gt a st The system is com patible with 14 16 20 and 40 pin microcontrollers it comes with AT89S8252 USB 2 0 programmer is built in and programming can be done without removing the microcontroller Many of industrial applications can be tested on the system temperature con trollers counters etc LV24 33 Development Board Complete Hardware and Software solution with on board USB 2 0 programmer and mikrolCD f MEN System supports amp n 64 80 and 100 pins PIC24F 24H dsPIC33F microcontrollers it comes with PIC24FJ96GA010 PIC24 16 bit Microcontroller 96 KB Flash Memory 8 KB RAM in 100 Pin Package Examples in BASIC PASCAL and C are included with in the system You can choose between USB and External Power supply LV 24 33 has many features that make your development easy Explore new PIC24F 24H dsPIC33F PIC MCU s with
132. at ing the original Note however that this requires specialised equipment not typically found in an intruder s toolkit It s the wiring from the module to the main alarm if used and to the power supply that s probably the most vulnerable It s therefore impor tant that all wiring is well concealed and completely inaccessible without first triggering an alarm Note that some alarm systems can be set up to detect cut wires and other forms of tampering Of course even simple alarm sys tems must have a well maintained battery backup supply to continue operating in a blackout Tag compatibility The RFID reader module used in this system will work with any EM4001 compatible read only tags A large range of tag styles is avail able but due to minimum order requirements some suppliers will probably only carry a couple of dif ferent types The most useful tag for this project is probably the key fob style It isn t much thicker than your typical automotive fob and it s virtu ally indestructible Best of all there are no batteries to go flat The credit card sized tag might also be popular There s no need to open your purse or wallet with one of these just swipe the whole thing past the reader for instant access EPE Everyday Practical Electronics August 2007 lmScan 5 USB Scan Tool e Diagnose any car with EOBD e 9600 or 38400 baud e Based on the ELM327 IC e Supported by
133. ble as a high quality recording studio capable of producing professional recordings This book tells you what software and hard ware you will need to get the best results You ll learn about recording techniques software and effects mixing mastering and CD production Suitable for PC and Mac users the book is full of tips how to do topics and illustrations It s the perfect answer to the question How do I use my computer to produce my own CD Order code PC120 10 95 92 pages 76 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 these 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 ho
134. button switch S1 In fact the board is designed to be free standing sup ported by four small screw on rubber feet one on each corner Fig 2 shows the parts layout on the PC board As can be seen the display LEDs DIP switches and pushbutton switch S1 are all arranged along the front of the board for ease of use Conversely the two connectors are at the rear to allow convenient cable connections The assembly should take you next to no time Begin by fitting the two connectors then the three wire links the DIP switches and pushbutton switch S1 Note that the DIP switches must all be fitted with their ON side towards the front of the board they may look upside down but this gives the correct switching sense Take particular care when installing switch S1 It must be installed with its flat body surface to the left ie one parallel pair of pins to the front and the other parallel pair to the back If it s installed incorrectly you ll get a permanent short across the 100nF ca pacitor and the switch won t work Next install the resistors and the SIL resistor array That done you can fit the small capacitors and the electrolyt ics Be sure to fit the latter with the correct polarity as shown on Fig 2 The semiconductors can now all be installed These include the diodes LEDs regulator and ICs As usual take care with the polarity of each of these Note that all six LEDs are fitted with their cathode
135. can also order p c b s by phone Fax Email or via the shop on our website on a secure server http www epemag co uk Everyday Practical Electronics August 2007 CLASSIFIED ADVERTISEMENTS Everyday Practical Electronics reaches more UK readers than any other UK monthly hobby elec tronics magazine our sales figures prove it We have been the leading monthly magazine in this market for the last twenty two years If you want your advertisements to be seen by the largest readership at the most economical price our classified and semi display pages offer the best value The prepaid rate for semi display space is 10 VAT per single column centimetre minimum 2 5cm The prepaid rate for classified adverts is 40p VAT per word minimum 12 words All cheques postal orders etc to be made payable to Everyday Practical Electronics VAT must be added Advertisements together with remittance should be sent to Everyday Practical Electronics Advertisements Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Phone 01202 873872 Fax 01202 874562 Email epeads Qwimborne co uk For rates and information on display and classi fied advertising please contact our Advertisement Manager Stewart Kearn as above Versatile Programmable PIC On Screen Di van d So eel VALVES AND ALLIED COMPO NENTS IN STOCK Phone for free list Valves books and magazines wanted Geoff Davies Radio tel 01788 574774 FOR PRICE VALVE CLE
136. ccess to the more fre quently used menu options The flowchart has its own window which initially has just Begin and End blocks The program elements and components are available in two columns of icons down the left edge of the screen The F i a ae ee Specify Component Pin Connections left hand column provides programming blocks such as loops and decisions while the other column contains external com ponents such as displays and switches The programming blocks are simply dragged and dropped in position in the drawing area and editing the charts is very easy In practice it is not quite as simple as placing some program blocks and com ponents in the drawing area and then compiling the program Component blocks must be connected to a port or ports in the appropriate fashion and pro gramming blocks often have parameters that must be set such as the condition to be met by a decision or the length of a delay This is achieved by double clicking the appropriate program block to produce a dialogue box With a component it is a matter of operating the menu button and selecting the Component Connections option The example shown in Fig 7 is for a seven segment display A slight problem with the flowchart approach to programming is that it tends to require huge amounts of screen space for even quite small programs M atters can be eased in this respect by saving part of a flowchart as a macro that can then be used a
137. ccordingly Everyday Practical Electronics August 2007 PC boards codes 629 Master and 630 Analogue available from the EPE PCB Service low profile plastic case size and type to choice see text D type 9 pin female connector SK4 9 pin termial strip 0 1in pitch and suitable panel mounting connector see text SK1 BNC sockets see text SK2 SK3 8 pin DIL sockets 14 pin DIL sockets 74LS245 Octal bus transceiver IC4 74HC595 8 bit serial input serial or parallel output shift register IC5 74HC4053 dual 3 way analogue multiplexers IC6 IC10 LMC6492 dual rail to rail op amps IC7 1C9 DS1267 100 dual digital potentiometer 100k IC8 1011 7805 5V 1A voltage regulator IC 12 78LO5 5V 100mA voltage regulators IC13 1C15 16 pin DIL sockets 20 pin DIL sockets 28 pin DIL sockets 40 pin DIL sockets self adhesive PCB supports 2 3 2 4 1 2 1 8 Serial connector lead to suit standard type not null modem DC power connector optional see text 1mm solder terminal pins multistrand connecting wire solder etc Semiconductors 1N4148 signal diodes D1 to D3 1N4001 50V 1A rectifier diode D4 PIC16F877 20 microcontroller 2OMHz preprogrammed see text IC 1 D43256BCZ 70 256 kilobit 32 kilobyte static RAM 70ns or similar IC2 No changing of the PIC code itself is required Further detail is given later The circuit diagram for the serial interface is
138. ce terminal emulator or batch files Serial cable can be up to 35m long Once programmed unit can operate without PC Includes plastic case 130x100x30mm Power 12Vdc 500mA Kit Order Code 3108KT 54 95 Assembled Order Code AS3108 64 95 Infrared RC 12 Channel Relay Board ee Control 12 onboard relays with included infrared remote con ka trol unit Toggle or momentary gy 15m range 112 x 122mm a Supply 12Vdc 0 5A Kit Order Code 3142KT 47 95 Assembled Order Code AS83142 59 95 PC Standalone Unipolar Stepper Motor Driver Drives any 5 6 or 8 lead unipolar stepper motor rated up to 6 Amps max Provides speed and direc ne tion control Operates in stand alone or PC controlled mode Up to six 3179 driver boards can be connected to a single parallel port Supply 9Vdc PCB 80x50mm Kit Order Code 3179KT 11 95 Assembled Order Code AS3179 18 95 Bi Polar Stepper Motor Driver also avail able Order Code 3158 details on website DC Motor Speed Controller 100V 7 5A Control the speed of almost any common DC motor rated up to 100V 7 5A Pulse width modulation output for maximum motor torque at all speeds Supply 9 18Vdc Box supplied Dimensions mm 60Wx100Lx60H Kit Order Code 3067KT 13 95 Assembled Order Code AS3067 19 95 Bidirectional DC Motor Driver also avail able Order Code 3166 details on website Hot New Kits This Summer Here are a few of the most
139. ch as fuel injection pumps water air intercoolers and water injection on Lead Acid Battery Zapper Kit KC 5414 11 75 post amp packing This simple circuit is designed to produce bursts of high energy pulses to help reverse the damaging effects of sulphation in wet lead acid cells This is particularly useful when a battery has been sitting for a period of time without use The effects are dependant of the battery s condition and type but the results can be quite good indeed Kit supplied with case silkscreened lid leads inductors and all electronic components with clear English instructions Luxeon Star LED Driver Kit KC 5389 9 75 post amp packing Luxeon high power LEDs are some of the brightest LEDs available in the world They offer up to 120 lumens per unit and will last up to 100 000 hours This kit allows you to power the fantastic 1W 3W and 5W Luxeon Star LEDs from 12VDC Now you can take advantage of these fantastic LEDs in your car boat or caravan e Kit supplied with PCB and all electronic components Jacob s Ladder High Voltage Display Kit KC 5445 11 75 post amp packing With this kit and the purchase of a 12V ignition coil available from auto stores and parts recyclers create an awesome rising performance cars You can also use it for headlight dimming and for running 12VDC motors in 24V vehicles The kit will control loads up to 10 amps although the addition of an extra MOSFET transis
140. ch means compiling it as an assembly language type and then programming it into a PIC chip via the M ulti programmer i aa MENN ERR Reg IE g 64 Por Fite praf Fig 8 above A simple program being run in the sim ulation mode The virtual onscreen components oper ate in a realistic fashion Fig 6 above left The initial screen when starting a new pro gram The Flowcode 3 program has a largely conventional user interface with the flowchart having its own window Fig 7 left Each component has a connection window that enables it to be connected to any port in the desired fashion This connection window is for a seven segment display Everyday Practical Electronics August 2007 Price Check Full details of the currently available E Blocks and accessories Flowcode demonstration software etc can be obtained from Matrix Multimedia Limited website at www matrixmulti media co uk telephone 08707 001831 fax 08707 001832 Flowcode is also available from the EPE Editorial office see page 35 It is also available as part of a Special Offer Package with TINA ProV 7 Basic for 42 55 plus VAT Pricing for Flowcode 3 is as follows Student home version 39 00 plus VAT Professional version 99 00 plus VAT 10 user network version 350 00 plus VAT Site Licence 699 00 plus VAT Note that the student home version does not include the full range of com ponents A free demonstrati
141. chantability and fitness for a particular purpose Because of possible 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 TechBites 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 HB7 Stirling Engine Base measurements 128 mm x 108 mm x 170 mm 1 kg Base plate beech Working rpm 2000 rpm min the engine has a aluminium good cooling Cylinder Bearing application 10 high class ball bearings Material screw side parts all stainless steel Cylinder brass Rest aluminium and stainless steel Available as a kit 80 75 or built 84 99 www mamodspares co uk HB9 Kit HB9 Stirling engine Base measurements 156 mm x 108 mm x 130 mm 0 6 Kg Base plate beech Working rpm approx 2 000 min Bearing application 6 high class ball bearings Material of the engine brass aluminium stainless steel running time 30 45 min Available as a kit 97 75 or built 101 99 www mamodspares co uk Base measurements 156 mm x 108 mm x 130 mm
142. chatronics SW300001 LT buy microchip com Software for this article via www epemag co uk dsPIC DSP based solution pertorms sophisti cated filtering that has removed the need for the optical sensor W hile this could have been performed on the 8 bit micro it has been achieved in a much simpler and faster man ner using the Microchip tools and dsPIC DSP The DSP library has also been used to provide a complete PID implementation that provides far better dynamic response than the 8 bit solution again with minimal program ming effort And the winner is In the article presented last month we demonstrated how to develop a simple motor control application using the PICI6F 917 microcontroller and the PIC DEM Mechatronics demonstration board We covered the basic operation of brushed DC motors and how to drive them using high and low side drivers as well as ina bi directional manner using the H Bridge Microchip PICs provide an ideal way of controlling these simple mechatronics sys tems A dditionally the ready availability of development tools and software for PICs allows the hobbyist to experiment with many possible applications In this month s article we have seen how it is possible to hack the M echatronics demo board and put a high performance 16 bit processor into the same socket With the extra features offered by the dsPIC30F 4011 we were easily able to per form filtering of back EMF signals and carry out the requir
143. ches SI to S8 are monitored by the scanning process and are normally Open pushbutton types The scanning process consists of taking each output high logic 1 in turn and checking the State of the input The input will normal ly be taken high each time an output is activated However closing the relevant Switch will pull the input low The series resistor protects the output of the printer port by preventing exces sive currents and the diode ensures that there is no interaction between each sec tion of the circuit R9 is a pull down resistor which ensures that the input will still be taken low even if it is a type that has a natural tendency to drift high The software simply has to output the correct sequence of values to the port 1 2 4 8 16 32 64 and 128 checking the state of the input line after outputting each value A switch has been activated Spee ee i dyed od ql sd ed og sd Fig 2 Here the circuit has been extended to accommodate sixteen switches It is essentially just a doubling up of the original circuit with an additional input error being used to monitor the second set of eight switches Everyday Practical Electronics August 2007 if the relevant bit of the Status register is low and a conditional instruction such as an If Then type is used to produce the appropriate response from the program Expansion This basic scheme of things is easily expanded with the aid of additional i
144. ctronics August 2007 13 V2 PC SCOPE TWOCHANNEL ANALOGUE NTERFACE ov ANALOGUE iz 5V EE R6 in the author s standard order Diode D1 and resistor R1 prevent power line distress during the application of pro gramming voltages Analogue channels The circuit diagram for the two analogue channels is shown in Fig 2 Both channels are identical and under control via PC commands and the PIC in conjunction with 8 bit serial input parallel output shift register IC5 Taking Channel 1 the analogue signal is input from socket SK2 via resistor R4 to the XO input of 3 way multiplexer IC6 of which only two ways are used This device allows the input of signal levels between 5V and 5V amplitude AC or DC as its VE pin is held at 5 V Normally the signal passes unat tenuated straight from pin XO to pin X and into op amp IC7a Path X0 X is additionally bypassed by the hard wired link between them This means that when path X1 X is selected resistor R5 is switched in allowing 14 this path to attenuate the signal level by one tenth due to the action of the potential divider now formed by resis tors R4 and R5 Calculations show that one tenth at tenuation occurs with R4 100k and R5 11kQ In reality a value of R5 10k will probably suffice for most re quirements of signal tracking display The output signal from op amp IC7a is routed in two directions to IC6 Y1 pin 1 as a DC signal and to
145. d fastening it all together using the four 25mm long M3 machine screws provided Your new TwinTen Stereo Am plifier is now ready for use Happy listening EPE 58 Everyday Practical Electronics August 2007 ELECTRONICS LTD 135 Hunter Street Burton on Trent Staffs DE14 2ST Tel 44 0 1283 565435 Chips Parts amp Kits for EPE Projects Programmed PICs and chips for most EPE projects Check our website or phone for prices We have supplied kits for EPE projects for almost 30 years amp Everyday Electronics Top Kits ICEbreaker P C16F 877 in cir cuit emulator Kit 900 34 99 1kV 500V Insulation Tester Inc drilled case Kit 848 32 95 Pipe Descaler High Power with led monitor Kit 868 22 95 18V supply KIT 914 Fax 44 0 1283 546932 20W Stereo A Wide band Low distor tion 11W channel Stereo 20W Mono True rms Real Power Short Circuit amp Overhez Protected Needs 8 to y 7 Kit inc all parts amp heatsink for stereo or mono 11 90 Latest Technology Stable Reliable high performance Ultrasonic PEST Scarer ran dom 32k pulses Kit867 19 99 P I Metal Detector Micro based design sensitive Kit847 63 95 MAGENTA Bat Detectors Our original famous KIT detector KIT 861 37 99 amp See the new built Mkilb and MKIII on the web All Prices Include VAT Add 3 00 P amp P per order or 7 99 for next day Chqs P O amp most majo
146. d have poles ands 3 ands 7 Weirdness E xplained All this seems a bit weird for a number of reasons First consider the poles 1 R C but I R4C is clearly anormal number so what s two dimensional about it And if s represents frequency how can it be nega tive Second at the pole the circuit s response seems to go to infinity whatev er Vin is but we do not expect to get infi nite voltages from Fig 1 All this is explained by the fact that we are dealing with two dimensional complex num bers we are literally in a different domain where the rules and interpretations are dif ferent The examples we have seen have poles which seem to be ordinary numbers this is a special case where one dimension of s happens to be zero but in general the pole value may not be equal to an ordinary num ber A negative value of s does not mean neg ative frequency in ordinary numbers Infinity in the s domain does not mean we get infi nite voltages in our RC circuit The pole is a significant point in the cir cuit s frequency response but what is its significance We can convert the complex frequency s 1 R C into an ordinary fre quency value using in this case 27 f v 1 R4C 2 so fp 1 2xR C From this Xc at the pole frequency call it Xcp is obtained by substituting this value for f lo 2AR C_ V fC Me into the expression Xc we can then use this in the expression for X Vo _ W on W j
147. ding RC I2C serial amp analogue voltage Relay reversing and fully solid state H bridge single and dual channel varients Sample pricing Dual 1A motor controller 17 09 10A motor controller kits from 19 87 75A controllers from 87 50 A wide range of radio control products including transmitters receivers servos gyros crystals interfaces leads etc Sample pricing 4 Channel 40MHz FM transmitter receiver crystals from 34 95 The PICAXE range of programmable microcontrollers Write in BASIC or Flowchart and download straight into the microcontroller so no expensive programmers are required The 8 pin version provides 5 i o pins 1 analogue input The 18 pin version provides 8 outputs and 5 inputs 3 of the inputs have analogue capabilities The 28 pin version provides 9 17 outputs 0 12 inputs and 0 4 separate analogue inputs Sample pricing e8 pin starter kit including software lead battery holder PCB amp components for 9 94 e28 pin version pictured above 21 74 We carry a wide range of robot kits from BEAM to full combat and includes the very popular Robonova biped walker Kits range in price from 16 95 to 689 05 built by enthusi asts amp school pupils from all over the UK Many are programmable via a PC RC or autono M mous p Full details of these AW and lots more W can be found on our website We carry a wide range
148. e soldered to the copper pads The three source indicator LEDs can now be installed These mount vertically at the very front of the board 54 Gl G OO Sje ak 100 22V e le P ail JOS e ANNO Rare 12V 22V 100 a 12V 1N5404 1N5404 4 7k immediately in front ofrotary switch S1 All three are orientated so the flat on the side of the body is towards the right First solder their leads to the pads underneath so the underside of each 047 27k 7 F erpe Jug L 8 1 10nF f QUonF s INI IA amp GROUND AS SHOWN CONNECT VR1 VR4 METAL SHELLS TOGETHER Fig 6 install the parts on the PC board as shown here but refer to the text before mounting the audio amplifier ICs IC3 and IC4 and switch S1 LED s body is just 12mm above the board After that it s just a matter of bending each pair of leads forward by 90 at a point 3mm below the LED body so that the LEDs will later Everyday Practical Electronics August 2007 This is the view inside the completed unit Take care to ensure that all polarised parts are correctly oriented ie the ICs LEDs diodes Zener diodes and the electrolytic capacitors protrude through the matching holes in the front panel of the amplifier At this stage the PC board assembly should be complete except for the two LM1875T audio output amplifiers IC3 and IC4 Don t install these yet that step comes later aft
149. e delving in order to find the sub section that enables the printer port settings to be changed but simply looking through the various sections of the program will do no harm provided you do not alter anything If you should accidentally make a mess of things simply exit the Setup program without saving the changes Y ou can then go back into the program and 60 try again Do not be tempted to play around with the BIOS settings unless you really know what you are doing Incorrect settings can make the comput er unstable or even prevent it from boot ing into the operating system Portable ports Laptop and notebook computers have become increasingly popular but they often provide problems when used with add on projects The most common problem is that the port operates at lower voltages than normal printer ports giv ing a lack of compatibility with many add on circuits and even with some printers Some portable PCs have printer ports that are non standard in other ways such as some of the handshake lines being absent There is not a great deal that can be done about this type of thing and you just have to accept that the port is non standard and that this will impose some major limitations Some portable PCs have a docking sta tion that provides various ports often including serial and parallel types An important point to bear in mind with this type of thing is that these ports are inter a DO 2 Ol a
150. e inc p amp p Overseas 4 75 surface 5 75 airmail LI enclose cheque P O bank draft to the value of LI Please charge my Visa Mastercard Amex Diners Club Maestro Card No Valid From Card Security Code The last 3 digits on or just under the signature strip SEND TO Everyday Practical Electronics Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU 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 August 2007 STORE YOUR BACK ISSUES ON CD ROMS VEHICLE FROST BOX Icy road warmin mts D F LATE VAL Pwa ANG SIWO GEAR p L PRI EFE Coir Che Back ese Ere cHROMATO colour To Sonne J A great way to buy EPE Back Issues our CD ROMs contain back issues from our EPE Online website plus bonus articles all the rele vant PIC software and web links Note no free gifts are included VOL 1 BACK ISSUES January 1999 to June 1999 Plus some bonus material from Nov and Dec 1998 i VOL 2 BACK ISSUES July 1999 to December 1999 Order on line from VOL 3 BACK ISSUES January 2000 to June 2000 kaa e A VOL 4 BACK ISSUES July 20
151. e 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 PRACTICAL FIBRE OPTIC PROJECTS R A Penfold While fibre optic cables may have potential advantages over ordinary electric cables for the electronics 135 pages 138 pages 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 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 P W 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 132 pages Order code BP374 5 45 DISCOVERING PICS W D Phillips A good introduction to PIC programming covering every PLUS HARDWARE thing you need to know to get you started No previous knowledge of microcontrollers is required b
152. e to re use soft ware across several projects and fixing instructions to absolute addresses is rather limiting Say you have written some useful 32 bit math routines that you just know will be useful in other programs Having these routines embedded in a single source file means you have to cut and paste the code out each time you want to re use it and re Specify the address of various data regis ters required Wouldn t it be nice if you could put your well defined routines into a single file assemble it and then forget about the insides of the code You know what the routines do you would like to be able to simply include the routines in your new projects and not have to bother about where to put them in memory and where to place their variables And that s where re locatable assembly comes in In this case each source file is assembled individually with no references to memory locations for code or data That obviously leaves questions about how instructions which reference absolute addresses such as goto or accesses to user data registers get resolved in files that have been previ ously built The answer is simple the assembler leaves them empty setting them 31 7 Id pf AAA S uthat isfz420 lkr v 1 6 2006705709 22 38 18 nairnj Exp Z E 7 File 18 2420 lkr 7 Sample linker script for the PICI8F2420 processor f Mot intended for use with MPLAB C18 27 use the linker scripts provid
153. easy programming of applications No need for a separate programming device Many example applications and firmware available see Compact Control Design download page Connector has standard 40 pin 0 1 pitch 0 6 wide footprint High quality tuned pin connectors suitable for most IC sockets and prototyping boards popular compilers Compatible with Microchip s MPLab free of charge programming environment Libraries and linker scripts included to support assembler programs MPLab and P0704 Developer Board The P0704 developer board is an ideal way to get started with our USB PIC module and motor driver modules All of the USB PIC module I O signals are available through screw terminals making connections to sensors switches lamps relays etc easy Ports B amp E 11 I O signals can also be configured with pull ups and input filtering suitable for connection to limit switches home position sensors etc The board supports up to 4 motor driver modules each module position accepts either a Stepper motor module or a DC motor module The board allows bus powered or self powered operation of the USB PIC module amp includes a P0615 mini regulator so only a single power supply is required for the motor driver modules All options are configured using jumpers and stepper motor drive current can be easily adjusted for each module by variable resistors All connections are made by high quality screw t
154. ed The power amplifier circuits are very Close to the Students Amp circuit but inevitably there are com ponent differences to provide different gain and so on How it works As you can see from the circuit diagram Fig 1 the amplifier is quite straightforward The left and right channels are identical with an input preamp stage followed by a tone control stage and finally a power amplifier stage We ll follow the signal path through the left upper channel in detail but the right lower channel is exactly the same Source selector switch S1a allows the user to select input signals from any one of three sources These are Everyday Practical Electronics August 2007 labelled CD MP3 and TUNER but any of these inputs can be used for line level audio signals from sources such as a DVD player a MiniDisc player games console or a VCR From the switch the selected sig nal passes through a simple low pass filter formed by a 2 7kQ resistor and a 680pF capacitor This filters out any RF radio frequency signals or noise that may be present with the incoming audio signals to prevent them from causing trouble After this the signals are applied directly to volume control potentiometer VR1a From the wiper of VR1a the signals pass through a 220nF coupling capaci tor to the input of IC1a which is one half ofa TLO72 dual FET input op amp IC ICla is used as an input pream plifier stage with its voltage gain set to 3
155. ed calculations for PID control The dsPIC Filter Design program available from M icrochip allowed the FIR filter coefficients to be simply calculated hence speeding the development time Finally we showed an empirical method for setting the PID parameters so that the motor could be smoothly operated even under load It should be clear that the task of controlling the motor could be achieved with the 8 bit microcontroller and where cost and size are most important this is a good choice Equally when higher per formance is needed then a 16 bit DSC could be used instead So in answering the question And the winner is the most accurate reply would be the user of course Rather than segmenting the marketplace Microchip offers a coherent platform choice where the most suitable processor can be used for the application and the distinction between 8 and 16 bits is made irrelevant 45 EVERYDAY ICS AND COMPUTER PROJECTS THE No1 UK MAGAZINE FOR ELECTRONICS TECHNOLOGY BACK ISSU ES We can supply back issues of EPE by post most issues from the past five years are available An EPE index for the last five years is also available at www epemag co uk or see order form below Alternatively 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 99 are available on
156. ed in a socket so that it can be removed and a different one fitted in its place For example a 3 2768M Hz baud rate crystal can be used in order to make serial interfacing more straightforward Fig 1 The Multi programmer has sockets to accommodate a wide range of PIC chips It can also be used as the basis of a PIC prototyping system While the programmer can simply be used as such the unit s full potential is reached by using it as the basis for proto type circuits One way of handling this is to simply connect your own external hard ware to the PIC processor via the 9 way connectors and suitable leads This is cer tainly a viable way of doing things and is one that will no doubt be preferred by some The alternative method is to use some E Blocks to provide all or some of the prototype circuit The range of E Blocks currently avail able is quite impressive with more than 30 different types on offer They range in complexity from simple banks of LEDs to Bluetooth and graphical display boards Three examples are shown in Fig 2 The obvious starting point is the proto typing board that has two ports with each one connecting to a nine way SIL socket The unit is fitted with a solderless prototyping board that has a pair of 30 by 5 prototyping areas plus the usual set of four power rails In addition the unit has a small area of board with double sided pads for prototyping of the sol dered variety There is also a
157. ed with that product LIBPATH CODEPAGE HAME vectors START 0x0 CODEPAGE NAME page START 0 2A CODEPAGE NAME idlocs START 0x200000 CODEPAGE NAME config START 0x 300000 CODEPAGE NAME devid START 0x3FFFFE CODEPAGE HAME eedata START 0xF00000 ACCESSBANE NAME accessram START 0x0 DATABANK NAME gpro START 0x860 DATABANK NAME gpril START 0x100 DATABANE NAME gpr2 START 0x200 ACCESSBANK NAME accesssir to 0 but makes a note that they need to be filled in at a later date That filling in might happen two seconds later or maybe two years later when you re use the code in another project The filling in is provided by anew program the linker The linker The linker is responsible for joining all these previously assembled or compiled if you are using the C language files together It examines each of the files find ing references to external variables and sub routines and works out where to place them in memory Having done this it then fixes instructions to point to the final locations that it has decided upon And having done that it then creates your hex programming file which you can then download to your PIC The linker doesn t modify your previously built files the modifications it makes are done in memo ry and transferred directly to the hex out put file To work out where it will place variables and code the linker must understand the layout of memory on your chosen PIC processor Stor
158. elow and take 40 off the total including VAT price FLOWCODE FOR PICmicro V3 Flowcode is a very high level language programming system for PICmicro 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 the control of complex devices like 7 segment displays motor controllers and l c d displays The use of macros allows you to control these electronic devices without getting bogged down in understanding the programming Flowcode produces MPASM code which is compatible with virtually all PICmicro programmers When used in conjunction with the Version 3 development board this provides a seamless solution that allows you to program chips in minutes Requires no programming experience Allows complex PICmicro applications to be designed quickly Uses international standard flow chart symbols ISO5807 8 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 18 28 and 40 pin devices New features in Version 3 include 16 bit arithmetic strings and string manipulation improved graphical user interface and printing support for 18 series devices pulse width modulation I2C new ADC component and many more PRICES Prices for each of the C
159. ember which one Phil built a door bell delay and my project was a metal detector fcon edad to a transistor radio can you cast your mind back and remember which was Alan s Other names in the frame which stick in the mind as contributors to magazine at the time are TR de Vaux Balbirnie and Barry West Andy via email Alan replied to Andy Nice to hear from you Andy haven t produced any projects for many years and am sorry to say that neither of the ones you listed were mine You can join the EPE Chat Zone our forum at www chatzones co uk to meet many fellow electronics enthusiasts and we have an online downloadable edition at www epemag com It is possible that some other readers may help as they sometimes have very long memories Terry Balbirnie is still producing some projects for us Back issues and books are available in the online shop at www epemag co uk which is the main magazine website Thank you for getting in touch and best regards Alan Winstanley EPE Online Editor m FERTA E a TE ES XGAMESTATION LEARN Sree St STEP Mow fo Ges oN Hah LA Sci App LAT ye Complate pacnagenlebook Integrated IDE m i Complete Software Development Kit eBook on Designing tne XGS Console Allg Fully Assembled XGS Micro Edition Uni jp L WWW XGAMESTATION COM SUPPORTMNURVE NET PH 925 736 2098lusa 73 Surfing The Internet Alan Winst
160. eptember 2007 issue will be published on Thursday Readers Services Editorial and Advertisement Departments 7 9 August 2007 see page 80 for details Everyday Practical Electronics August 2007 l All prices INCLUDE 17 5 VAT Postage amp Packing Options Up to 2Kg gross weight UK Standard 3 7 VISA Day Delivery 3 95 UK Mainland Next Day Delivery 8 95 Europe EU 6 95 Rest of World 9 95 up to 0 5Kg Order online for reduced price UK Postage Payment We accept all major credit debit cards Make cheques PO s payable to Quasar Electronics Call now for our FREE CATALOGUE with details of over 300 kits Quasar Electronics Limited PO Box 6935 Bishops Stortford CM23 4WP United Kingdom Tel 0870 246 1826 Fax 0870 460 1045 E mail sales quasarelectronics com Web www QuasarElectronics com UROCARD SMWFICH Electron SUO QUASAR electronics Get Plugged In PIC amp ATMEL Programmers We have a wide range of low cost PIC and ATMEL Programmers Complete range and documentation available from our web site Programmer Accessories 40 pin Wide ZIF socket ZIF40W 15 00 18Vdc Power supply PSU010 19 95 Leads Parallel LDC136 4 95 Serial LDC441 4 95 USB LDC644 2 95 NEW USB amp Serial Port PIC Programmer USB Serial connection ree supported ZIF Socket and foe USB lead extra 18Vdc Kit Order Code 3149KT 37 95 Assembled Order Code AS3149 49 95
161. er they have been bolted to the rear panel Side actuator knob With the board assembly now com plete you can now make the special side actuator knob for the selector switch This is made by first modifying a standard knob by cutting off its top and bottom This is then fitted with an actuator lever cut from a small piece of 3mm Perspex or acrylic sheet Everyday Practical Electronics August 2007 the accompanying diagram in Fig 7 gives you a template The two are then cemented together using epoxy adhesive First cut out the actuator paddle from a small piece of 3mm thick Pers pex using a hacksaw and then smooth it all around using a small file Lightly sand one side as well using fine sand paper so it has a matt surface Next cut off the top and bottom of a 20mm skirted knob at the positions marked in Fig 7 This should leave only the knob section immediately around the brass insert It s a good idea to smooth both cut surfaces top and bottom with fine sand paper so they re flat and free from burrs Finally mix up a small amount of Araldite or similar epoxy adhesive and cement the lower surface of the knob to the matt surface of the Perspex actuator paddle This should be done with the knob positioned as close as possible to the centre of the round hole in the paddle and with the knob orien tated so its grub screw hole is pointing at 12 o clock when the paddle arm is positioned at 5 o clock
162. ere are a number of classical filtering methods and we are going to select a finite impulse response or FIR filter This has a major advantage in being simple to under stand and is readily implemented using the tools that Microchip provides for us The ADC is sampling during this time Back EMF Generated by Motor when PWM is turned off PWM Generated by Motor Control Module PWM Voltage ADC Sampling Fig 3 Back EMF voltage measuring 44 FIR filter works by storing a number of previously sampled values in a delay buffer At each sample time a new value is added into the delay buffer and then all of the elements are multiplied by coefficients with the results being summed together This summed value is the final output of the filter There are many factors that go into the design of the filter coefficients and they are primarily controlled by the sampling fre quency passband and stop band frequen cies and the degree of signal rejection required in the stop band Calculating the coefficients by hand can be time consum ing and this task is far better performed by a computer Microchip provides a low cost design tool called dsPIC FD and its user inter face can be seen in Fig 4 The program will take a set of filter specifications and pro duce graphs show
163. erminals The board has been designed to accommodate other driver modules as they become available P0613 DC Motor Pulse width modulation control for DC motors electro magnets etc It has a motor supply voltage of 8 to 36V The maximum drive current is 2 5 Amp There are pulse and direction inputs n The PWM control is up to 100KHz Mode input for controlling motor braking and sleep input for power saving There is built in short circuit and over temperature protection a fault output pin activates if either of these is detected No heat sink is required The board has dimensions of 66x30mm and is 12mm high There is an adapter available providing easy to use screw terminals for all connections All the control inputs are opto isolated kou DODOMDNODOOHOHOOOs 4161 JU P0612 Stepper Motor Driver The unit has a motor supply voltage of 5 to 30V The maximum drive current per phase is 750mA It has current mode control The drive current is controlled with a resistor It has a selectable step size of full half 1 4 1 8 There is a step frequency of 0 to 200KHz and reset and sleep inputs for initialization and power saving It is a compact size with dimensions of 66x32mm by 12mm high The P0612 does not require a heat sink There is an adapter available which provides easy to use screw terminals for all connections All the control inputs are opto isolated
164. et you test them quickly without the need for a PC or test software By JIM ROWE ASICALLY THIS DEVICE is a simple hardware simulator It allows you to manipulate the port s data and control lines monitor the status lines and even send the printer or other equipment a strobe pulse The idea for the Printer Port Simula tor came about while we were develop ing some hardware We struck a rather tricky timing fault and subsequently wasted a fair bit of time trying to work out whether it was due to a problem with the hardware or a bug in the software The same sort of problem can oc cur when you re trying to track down a fault in other kinds of PC driven 66 equipment of course It can even happen when you re getting weird problems with a printer We ended up resolving our particu lar problem by lashing up this Printer Port Simulator This allowed us to send basic control signals to the hardware and monitor its status lines without having to worry about software debug ging until later It proved to be very effective and enabled us to track down the cause of the timing error Later on we realised that our Printer Port Simulator could also be used as a general troubleshooting tool to solve similar problems So here it is and there s really very little in it just two lt ideal for trouble SNOGHAG lt Lets you manipulate the data amp Control ines as 6 LEDs for skatus monitoring lt Low c
165. f Windows from 98 through to XP but it would not install or work properly with Windows Vista but we are assured that this has now been sorted out Everything installed easily using a computer running Windows XP with the programmer being correctly identified and installed in standard plug and play fashion The program appears in a small window when launched Fig 3 which has a diminutive menu bar and a few buttons Further windows appear when undertaking tasks such as loading a program file con File view tions B Open Sn Wc mcmiche o Configur pIC16F88 ma Select chip Watchdog timer Oscillator a RC 5 Gn C TAL m ot internal rt Cont sere en A Seach To Benet PPP V3 Satriy PICmi a Configure PiCmicra Men sir iis SC PPPV Proge1a4 4 812439 counter HE Fig 4 This pop up window is used to select the required PIC chip and set the appropriate configuration figuring the PIC Fig 4 and reading the contents of a PIC processor Fig 5 When everything is set up correctly it is just a matter of operating the Send to PIC micro button and waiting for con firmation that the chip has been pro grammed success fully On trying PPP and the Multi pro grammer with a few test programs they always performed flawlessly Flowcode V3 Experienced PIC programmers will probably be perfectly happy with the PPP program which is all that is needed in
166. from the ADC chip and from the digital interface chip IC4 It will not be discussed further here Resistor R2 ensures that the memo rys OE line is normally held high unless actively pulled low by RCO it could otherwise float ifthe PIC is being programmed in situ on the PCB The latter chip IC4 is used when the selected mode is for 8 bit digital data input rather than an analogue input allowing the logic levels of each external data bit to be stored ap propriately External data is input to this chip via connector SK1 At the end ofrecording each 8K batch of data 8192 bytes the PIC changes from sampling mode into playback mode outputting the data held in the memory to the PC as discussed later Following this the PIC automatically returns to sampling mode and the proc ess begins again and so on The PIC may be programmed in situ via connector TB1 whose PCB pins are Everyday Practical Electronics August 2007 5V DIGITAL V2 PC SCOPE MASTER CONTROL a sl azo eee eee se eee l Eee ee m ao a ea N S ILE 7 ANALOGUE LI NINE TT D1 SEE TEXT DATA CLK TB1 O Q Vpp OV CLK DATA RST LATCH BAUD RESET TX IC16 RX DIGITAL INPUTS SK1 14 DESE L KA ee ee ee onn a A ee ee l nn aA KE a es ee pan o 2 0 DB7 EXT CLK OV OV Fig 1 Circuit diagram for the master control unit Everyday Practical Ele
167. ginning of the file on lines beginning with II These lines are ignored by the linker pro gram and you can place them in the file to provide explanations of any changes you make The comments in the standard script files don t provide any useful information SO you Can just ignore them The LIBPATH line specifies where the linker program will look for any library files that are required in the link process This is an advanced feature that you will not need to change for now The CODEPAGE sections identify the address ranges of the flash memory inside the PIC While in reality there is a single bank of flash memory ranging from 0 to OX3FFF for this device the linker script splits these into several different regions By default any code you write will be placed in the page region by the linker But what about those Reset and Interrupt rou tines that must go at very specific loca tions The linker script provides a special section for this called vectors It specifies a range of memory that is protected the linker will not place code here it s for you to specify what goes in there and of course it s reserved this way specifically for you to place your code here in an absolute way We ll mention how later Memory locations The next section in the linker file sepa rates out the RAM into different memory For C18 projects END 0x29 END 0x3 FFF END 0x200007 END 0x30000D END 0x3FFFFF END OxFOQOFF END 0x7F
168. gpack to the input socket and apply power If all is well the centre red LED on the front panel should light assuming the Source switch is in that position The other two LEDs should light when the switch actuator is moved to their respective positions If the LEDs do light correctly the supply voltages are probably OK However if you d like to make sure you can check the DC supply voltages using a multimeter The simplest way to do this is to connect one lead of the multimeter to the tinned copper wire that connects the bodies of the control pots and then use the other lead to touch various supply voltage points As a guide several convenient voltage test points are marked on the PC board overlay diagram Fig 6 For example near the ends of the two 470Q resistors near the centre of the board you should be able to measure 22V 22V 12V and 12V as shown Similarly you should be able to meas ure 22V on the anode of diode D3 and 22V on the cathode of diode D1 If all of these voltages measure cor rectly ie within 0 5V your amplifier is probably working correctly To con firm this switch off connect suitable loudspeakers and connect a suitable audio source eg a CD player or AM FM tuner to a pair of input sockets Finally apply power and check that the unit is working properly by varying all the front panel controls All that remains now is to finish the assembly by fitting the top half of the case an
169. h 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 Order code NE30 20 00 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 263 pages 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 and a RTTY serial to parallel converter A full range of interesting and useful circuits for short wave enthusiasts Order code BP304 4 45 AN INTRODUCTION TO AMATEUR RAD
170. handshake outputs at this address so 32 must be added to the value written to these ports in order to keep the data lines set as inputs It s a Setup There can occasionally be problems in setting the port to the input mode It is unlikely that this mode is not supported at all unless the computer is a really old type such as an 80386 80486 or very early Pentium based PC The more usual problem is that the port does not default to a mode that sup ports bidirectional operation of the data lines This can usually be cured by enter ing the BIOS Setup program and setting the port to a suitable mode such as the EPP Enhanced Parallel Port type Methods of entering the Setup pro gram vary from one PC to another but it is usually just a matter of operating the Esc or Del key during start up before the computer starts to boot into the oper ating system Sometimes there is an on screen message giving details of how to enter the Setup program The facilities available from Setup programs vary considerably from one to another M odern Setup programs often have numerous sections with most of these sections leading to what is effec tively a structure of sub menus Older Setup programs are mostly more straightforward but they usually have a number of sections and some sub sections The parallel port is usually controlled via a section called something like Integrated Peripherals It will probably be necessary to do a littl
171. he time to start think ing about other issues Is it available in a package can solder Does my programmer support this part Does my debugger support this part Can obtain the part from a distributor As you can see you may well have to go round this loop several times before a suit able part can be found The more complex your requirements the more times you will have to go round this loop finding and then discarding potential candidates Low voltage problems The most difficult issue to solve is that of low voltage operation as there is a lim ited number of parts that support operation below 5V W hen problems like this occur you may want to start thinking about adding addi tional circuitry to solve these For example L ow voltage operation Consider running the processor on a sep arate higher voltage and use a buffer cir cuit to level shift the I O signals between the processor and the rest of the circuit Low cost ICs are available to do this or you can do it using discrete components Insufficient 1 0 pins Consider using a simple 8 bit latch IC to extend the number of I O pins 8 bit latch es are very cheap and readily available Special interfaces If your chosen PIC does not provide SPI I2C or UART peripherals consider bit bashing them over standard I O pins Source code for bit bashed implementa tions are readily available on the download page of the EPE website and elsewhere on
172. help wondering if the starry eyed bright young things at Google have thought all this through properly Today major concerns are being voiced about the legality of a European Street View Google argues that all the data is in the public domain anyway but do we want ourselves recorded for all to see You can email the author at alan epemag demon co uk Google Earth is a global mapping program that can home in on virtually any location in the world Screenshot the Humber Bridge north towers near Hull as seen by Earth Use the controls top right to move around Everyday Practical Electronics August 2007 lectronics Teach In Free CD ROM Mike Tooley A broad based introduc tion to electronics find out how circuits work and what goes on inside them Plus 15 easy to build projects The 152 page A4 book comes with a free CD ROM containing the whole Teach In 2006 series orig inally published in EPE in PDF form interactive quizzes to test your knowl edge TINA circuit simula tion software a limited ver sion plus a specially writ ten TINA Tutorial together with simulations of the cir cuits in the Teach In series plus Flowcode a limited ver sion a high level programming system for PIC microcon trollers based on flowcharts The Teach In series covers everything from Electric Current through to Microprocessors and Microcontrollers and each part includes demonstration circuits to build on breadboards or
173. hese must be installed first as shown in Fig 2 Bend the leads of the regulator REG1 90 at about 5mm from the body so that when it is installed the hole in its metal mounting tab lines up with the hole in the PC board Attach the regulator firmly to the board with an M3 x 6mm screw nut and washer before soldering the leads Diode D2 must be installed with its banded cathode end oriented as shown With both REG1 and D2 in place turn the board over and cut off the protruding component leads flush with the PC board surface Next on the top side of the board install all the low profile components first starting with the resistors and diodes Again the diodes D1 D3 and Zener diode ZD1 must go in with the banded ends around the right way Install the ID 12 module next Note that because of the gap between pins 10 and 11 it can only go in one way On our module one row of pins were slightly out of line and needed tweak ing to get an easy fit into the PC board 4 Band Code 1 brown black orange brown brown black red brown red red brown brown brown green brown brown brown black black brown 1 PC board code 628 available from the EPE PCB Service size 51mm x 71mm 3 2 way 5mm 5 08mm terminal blocks CON1 CON2 1 6 way 2 54mm DIL header JP1 JP3 3 jumper shunts 1 20 pin IC socket 4 M3 x 10mm tapped nylon spacers 5 M3 x 6mm pan head screws 1 M3 nut and washer EM4001 compatible 125kHz RFID tag
174. ieve this the program takes the potentiometer value and measured speed value scaling them all into the range 0 to 1023 Likewise the control output is scaled back up so that a value of 1023 equals a 100 duty cycle PWM waveform Once all of the variables are in the same range then the P and parameters were arrived at by experimentation with P equal to 0 65 and equal to 0 05 The PID terms are not used directly and must be convert ed into a suitable form for the function The fragment in Listing 3 shows how the PID function is typically used Listing 3 create a PID structure tPID motorPID set up the pointers to memory for storing coefficients and history motorPID abcCoefficients gabcCoefficient 0 motorPID controlHistory amp controlHistory 0 clear the history buffer PIDInit amp motorPID assign the PID terms coeffPID 0O Q15 0 65 coeffPID 1 Q15 0 05 coeffPID 2 Q15 0 0 precalculate the PID coefficients PIDCoeffCalc coeffPID 8motorPID finally call the PID update routine motorPID measuredOutput IpfOutput motorPID controlReference vPot PID amp motorPID dutyCycle long motorPID controlOutput The complete program is capable of driv ing the motor at a varying speed just as the PIC16F917 solution could However the Everyday Practical Electronics August 2007 dsPIC30F4011 Datasheet Mechatronics Demo Board dsPIC Filter Designer Lite DS70135 me
175. ify the danger type smoke or CO USB Digital Storage Scope The DSO 101 from A udon Electronics is a USB powered digital storage oscillo scope with dual 20MS s inputs and a 2M Hz bandwidth that is small enough to fit in your pocket It packs some powerful features including a hardware preamp adjustable digital triggering and 32Kb memory depth on each of the two 8 bit input channels It is powered by an open source graphical user interface for Windows and Linux After the warning handset has been alert ed to danger it automatically converts to an escape torch when taken out of its holder The strong white light helps guide the way out of the building and the handset emits a locator chirp so anyone holding the hand set can be readily found When the danger has been investigated and eliminated sim ply replacing it into its holder resets the handset The DSO 101 is a general purpose two channel oscilloscope for teaching development and debugging of electronic circuits Channels A and B are sampled simultaneously and stored in oscilloscope memory before being sent for display to the host computer Consequently they are always time aligned and triggered from the same trigger signal The easy to use software supports multiple triggering modes waveform scrolling saving waveforms to a file and cursor measurements Source code is included The user can add and modify the graphic user interface as desired The PC connec
176. igh Power FM Room Bug Our most powerful room bug Very impressive perform ance Clear and stable out put signal thanks to the extra circuitry employed Range 1000m 9V Supply 6 12V DC 9V PP3 battery clip supplied 70x15mm Kit Order Code 3032KT 9 95 Assembled Order Code AS3032 17 95 MTTX Miniature Telephone Transmitter Attach anywhere along phone line Tune a radio into the signal and hear exactly what both parties are saying Transmits only when pnone Is used Clear stable signal Powered from phone line so completely maintenance free once installed Requires no aerial wire uses phone line as antenna Suitable for any phone system worldwide Range 300m 20x45mm Kit Order Code 3016KT 7 95 Assembled Order Code AS3016 13 95 Wide Band Se a FM Transmitter PLL based crystal locked wide band FM transmitter delivering a high quality stable 10mW output Accepts both MIC audio signal 10mV and LINE input 1v p p for example hi fi CD audio mixer like our kit 1052 or computer sound card Supply 9 15Vdc Kit Order Code 3172KT 19 95 Assembled Order Code AS3172 32 95 3 Watt FM Transmitter a Small powerful FM transmitter Audio pre amp stage and three RF stages deliver 3 watts of RF power Use with the eizciel microphone supplied or any line level audio source e g CD or tape OUT mixer sound card etc Aerial can be an open di pole or Ground Plane Ideal project
177. iles that neatly package the pre assembled object files into one file We ll demonstrate this with a simple example in the conclud ing article next month and take a look at some of the more advanced features of MPLAB 33 EPE IS PLEASED TO BE ABLE TO OFFER YOU THESE ELECTRONICS CD SEES TRON PROJECTS SS a aes Logic Probe testing 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 EE ON CIRCUITS 6 COMPONENTS V2 0 Circuit simulation screen Provides an introduction to the principles and application of the most common types of electronic componenis and shows how they are used to form complete circuits The virt
178. illion it is usually the time that the marketing department steps in and demands better performance and more features from our new mechatronics device For instance in the case of the l the last article in our mechatronics Nou AVdd ANO RBO AVss AN1 RB1 PWMI1L REO AN2 RB2 PWM1H RE1 AN3 RB3 PWM2L RE2 AN4 RB4 PWM2H RE3 ANS RB5 PWM3L RE4 BDC motor they may decide that measur 2 ing the motor s speed using the optical ma YA a interrupter is costing too much money and a that they would like to remove it and meas W MI ure speed using back EM F sensing T D RITXRFI The PIC16F917 used last month is easi OSc1 U2RXIRF4 ly capable of performing this task but when osc2 U2TXIRFS T2CK RC13 PGC U1RX even more complex features are required then we may need to consider a higher specification of microcontroller T1CK RC14 PGD U1TX
179. ime you want to arm or disarm your security system End all these little annoyances with a wave of your hand and our RFID Security Module By PETER SMITH ANY HOME SECURITY sys Me include a keypad situ ated at the main point of en try or exit More complex systems may also include a battery powered remote control device While these systems have their own merits they can also be more than a little inconvenient Having to punch in a code repeat edly can be quite irritating as can the discovery that the batteries in the remote have finally given up the ghost This point of entry system solves these problems because it requires no physical contact and no batteries Essentially the system consists of a reader module and one or more tags Based on RFID Radio Frequency Iden tity technology each tag is encoded with a unique identity When a tag is brought within range 22 of the reader it is energised by the reader s magnetic field It then transmits its unique code to the reader which validates the code and arms or disarms the alarm system accordingly This system also includes the ability to operate an electric door strike A sim ple wave of your hand and an Open Sesame incantation are all that are required for the door to your castle to spring open Well the Open Sesame incantation isn t really necessary System overview The RFID Security Module is built on a single PC board mea
180. ing equipment is returned because people cannot make it work And of the Philips equipment that is returned we find that 98 is no fault found MUSEUM OF COMMUNICATION The Museum of Communication in Burntisland Fife is about to open its doors to yet another ambitious exhibi tion Entitled From Big Band to Broadband this year s event takes visi tors through the changing face of home entertainment in the last 80 years From gramophone to iPod from candlestick telephone to mobile with Bluetooth from Baird s TV to HDTV and from crystal set to Internet all within the span of a life time The Museum studies collects pre serves and exhibits artefacts and infor mation which illustrate the development of communications technology It is cre ating a high quality communications museum in Burntisland that will help people to learn how the technology we take for granted today has been developed From Big Band to Broadband is open from Ilam to 5pm on Saturdays and from lpm until 5pm on Sundays and Wednesdays from 21 July until 16 September Admission which includes refreshments costs 3 adult 1 50 accompanied child and 8 50 family For further details tel 01506 823424 Secretary or email mocenquiries tiscali co uk Everyday Practical Electronics August 2007 SIMPLICITY NEEDED FireA ngel one of the UK s leading forces in the manufacture and supply of home safe ty devices has further expanded its prod
181. ing information about every single device within the linker program would be very cumbersome and inflexible so the linker relies on a linker script a file that you add to your projects file list You don t need to create a linker script yourself Microchip have provided a linker script for every processor type they produce To add a linker script to your project right click over the Linker Scripts line in the project s mcw window click Add Files and select the appropriate file from the MPLAB linker directory You will find them here C ProgramF iles M icrochip M PA SM Suite LKR There are several versions of linker scripts for each processor to enable addi tional advanced features that we won t dis cuss here the file names all follow a sim ilar format For example 18F 2420 lkr standard 18F 2420 elkr extended 32 START 0XF80 Fig 2 Linker script Choose the standard linker script for now You only specify one linker script so don t go looking to add another one It s the act of adding a linker script to your list of project files that causes the IDE to switch from absolute to re locatable build mode Linker scripts Let s take a look at a typical linker script for the PIC 18F 2420 as shown in Fig 2 All linker scripts follow a similar format Some comments a library path specifier information about the code memory and information about the data memory The comments are shown at the be
182. ing the response to vari Ous inputs But best of all it has the ability to output an assembly language file con taining all of the filter coefficients and the filter data structure This can then be com piled into our program Given that our sampling frequency is 175Hz the filter shown was generated for a passband of 4Hz with a stop band of 10Hz and 60dB of ripple in the stop band To obtain the specified output response the dsPIC FD created a filter with 107 coeffi cients and delay stages or taps Because of the highly efficient architecture of the dsPIC the multiplication and summing of all of these values can be performed in 164 processor cycles or 10 microseconds at our selected processor speed Listing 2 while 1 bSampleReady 0 wait for a new sample to come in while oSampleReady filter the incoming data to provide a noise free signal FIR 1 amp lpfOutput fraction al amp BackEMF amp lpfFilter The values were chosen to be appropri ate for the velocity control algorithm in the main function which runs at approximately 5Hz Once the code has been generated a simple call to the FIR function will per form all the necessary steps to produce a final smoothed output The code fragment is shown in Listing 2 and in the FIR call the first parameter is the number of new samples The next is a pointer to the output value followed by the input value obtained in the ADC sampling routine and finally comes
183. ings Material screw side parts total stainless steel Cylinder brass Rest aluminium stainless steel Available as a kit 140 25 or built 144 50 2kW WIND TURBINE KIT The 2kW wind turbine is sup plied as the following kit turbine generator 48v three taper twisted fibreglass blades amp hub 8m tower four x 2m sections guylines anchors tensioners clamps foundation steel rectifier 2kW inverter heavy duty pivot tower 1 499 BULL GROUP LTD UNIT D HENFIELD BUSINESS PARK HENFIELD SUSSEX BN5 9SL TERMS C CARDS CASH PO CHEQUE OR ONLINE ORDERING PRICES PLUS VAT UK DELIVERY 5 50 TEL 0870 7707520 FAX 01273 491813 sales bullnet co uk Solar Panels We stock a range of solar photovoltaic panels These are polycrystalline panels made from wafers of silicon lami nated between an impact resistant transparent cover and an EVA rear mounting plate They are constructed with a lightweight anodised aluminium frame which is predrilled for linking to other frames roof mounting structure and contain waterproof electrical terminal box on the rear 5 watt panel 29 ref 5wnav 20 watt panel 99 ref 20wnav 60 watt panel 249 ref GOwnav Suitable regulator for up to 60 watt panel 20 ref REGNAV Solar evacuated tube panels 20 tube shown These top of the range solar panel heat collectors are suitable for heating domestic hot water swimming pools etc even in the winter One unit is adequate for an average household 3
184. int The evolution of Intels microprocessors THE END TO ALL DISEASE by Aubrey Scoon The original work of Rife COLLECTING AND RESTORING VINTAGE RADIOS by Paul Stenning THE LIFE amp WORKS OF KONRAD ZUSE a brilliant pioneer in the evolution of computers Valid FROM 22nseneeas Expiry Date Maestro Issue No l l l l l l l l l SEND TO Everyday Practical Electronics i Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU l l l l l l l l l l Tel 01202 873872 Fax 01202 874562 E mail orders epemag wimborne co uk Payments must be by card or in Sterling cheque or bank draft drawn on a UK bank Normally supplied within seven days of receipt of order Everyday Practical Electronics August 2007 47 VAlittillekstene oKalm p lite Withinsiu Hi DGUSHINIG IVs ae Pieinfionmiaintcie DVR IVEROW ECE ERERES M IMH Want a compact amplifier to team with your Discman MP3 player games machine or whatever This tiny stereo amplifier puts out a surprising amount of power considering that it runs from a 16V AC 1 25A plugpack OT ONLY IS THIS a gutsy little amplifier it is an ideal learn while you build it project for high school and tech college students It all fits onto a single largish PC board with no 230V AC mains voltages present that s taken care of by the 16V AC plugpack The TwinTen has inputs for three stere
185. l Professional 10 user Robotics amp Mechatronics C Site licence Assembly for PICmicro V3 C for 16 Series PICmicro V4 Flowcode V3 for PICmicro Digital Works 3 0 Version required PiCmicro Development Board V3 hardware TINA Pro V7 Basic Flowcode V3 Hobbyist Student Electronic Components Photos Project Design Single User Project Design Multiple User under 500 students Project Design Multiple User over 500 students Note The software on each version is the same only the licence for use varies OOOOO OU dddo enclose cheque PO in sterling payable to WIMBORNE PUBLISHING LTD for Please charge my Visa Mastercard Amex Diners Club Switch I l l l I I I l i VANG FIORE kis diya a kak ini a eee ee as Card Expiry dale criss cp aa m ek ae ae ene aa cba a pi aj I I l l l I Gard NO Siri Fe det bree ase eee tg Pace Gd ed oe ee Re E E des Maestro Issue No Card Security Code The last 3 digits on or just under the signature strip ee ee ee en 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 36 Everyday Practical Electronics August 2007 a EVERYDAY PRACTICAL ELECTRONICS UK readers you can SAVE 54p on every issue of EPE How would you like to pay 2 96 instead of 3 50 for your copy
186. ld prob ably be better placed in a separate file maybe called uart asm This will then contain only the higher level functions related to accessing the GPS module without any lower level hardware specif ic code This not only makes the code easier to read but will mean in the future should you implement a similar project on another processor you could replace the UART routines maybe for bit bashed routines without even having to look in the gps asm file The same principle applies to the eep rom asm file the SPI routines needed to communicate with the EEPROM are generic functions that could be re used at a later date Following these ideas the final list of files would look like this main asm gps asm eeprom asm uart asm spi asm File contents Going back to the contents of these files main asm will hold all the ancillary soft ware such as the interrupt and reset rou tines higher level application code and configuration register settings Choosing the correct configuration settings is vital to the operation of your program but there is a trick to how you select them More on that shortly Having decided on the files that you will have in your project the next step is to cre ate them all of them even before you know what you are going to be putting inside them It s important to do this before you start getting into the fine detail of coding get the structure of your software in place first so you don t
187. lect Mode 2 3 or 4 If you don t need the door strike function then it s not important which alarm mode you choose MODE 4 ALARM MODE DOOR STRIKE POWERED ON ARM amp DISARM MODE 3 ALARM MODE MODE 1 KEYLESS MODE DOOR STRIKE POWERED ON TAG VALIDATION ALARM MODE DOOR STRIKE POWERED ON DISARM DOOR STRIKE POWERED ON ARM 26 Everyday Practical Electronics August 2007 12V DC SIREN 600mA MAX 12V DC DOOR STRIKE SOLENOID 1 3A MAX 8 8 3 pa Fig 6 a an electric door strike can Fig 6 c basic alarm functionality i L be connected for easy access to can be achieved by connecting a SY your home siren directly to the alarm output D Alternatively this output can drive a 12V relay TAMPER SWITCH Fig 6 d a tamper switch is mandatory unless the unit is completely inaccessible Here s how to connect one TO MAIN ALARM TO MAIN ALARM OR IMMOBILISER 12V SLA BATTERY 1 2 7ZAh Fig 6 b the arm and alarm outputs can be used to interface the module to an existing alarm system The arm output can also be used with an engine immobiliser circuit in a Car This operation also erases all of the microcontroller s EEPROM so if you ve decided to switch modes after programming some tags you ll need to program them again Now power off and remove the jumper wire as well as the shunt on JP1 The module is now ready to be programmed for tag recognition
188. less than peaceful existence which is why later some security related areas were hastily airbrushed out of existence in their map database Then there is Google Earth a mind blowing application that allows you to circumnavigate the Earth like a satellite zooming into almost any location you can think of Geographical data can be super imposed on top showing for example a 3D planetary view of global oil consumption see earth google com gallery index html U sers can email aerial snapshots and add map pins for favourite locations and let the software fly users around the planet integrated into itis a Find Businesses database Google Earth software 15M B is free and is Windows M ac and Linux compatible Google Street View of the B amp H Photovideo store in New York as mentioned in last months Net Work The panoramic image is zoomable and can be rotated 74 Street wise Hungry to find applications for its processing prowess and with seemingly no limit to its appetite for more input Google M aps has Started to integrate a street level 3D photo realistic view of some cities The Google Street View maps google com help maps streetview lets you take a virtual 3D daytime tour of the main streets of N ew York Las Vegas San Francisco Miami and more It captures a 3D panoramic snapshot of street life for all to see The blue lined routes on Google M aps are those that have been traversed by the Street View mapm
189. lf of VR4 forms a similar voltage divider with the 4 7kQ resistor in the right channel In addition because the two dividers share VR4 their division ratios vary in opposite fashion when the wiper is turned one way from the centre position the gain is reduced in the left channel but increased in the right channel and vice versa Fig 1 right the circuit consists of identical input preamp stages IC1a amp IC1b followed by a tone control stage IC2a amp IC2b and finally power amplifier stages IC3 and IC4 Switch S1 selects the input signal with LEDs1 3 indicating the selected signal source So VR4 provides a see saw or dif ferential adjustment of the gain in the two channels allowing them to be matched or balanced to compensate for any difference in the incoming signal levels Power amplifier IC IC3 is an LM1875T power amplifier IC which comes in a TO 220 package with five connection leads and a metal tab for connection to a heatsink It s connected as a basic amplifier stage with a voltage gain of about 18 times as set by the 82kQ and 4 7kQ negative feedback resistors ie 1 82k 4 7k The 4 7uF capacitor in series with the 4 7kQ resistor is used to give the amplifier full DC negative feedback for maximum thermal stability In ad dition the series 220nF capacitor and 2 7Q resistor connected between IC3 s output and ground form a Zobel filter network to ensure that the amplifier is stable
190. li a ki A p son u ho kon i n j i q po L F F 1 pon l a L yonn a Ta F hangs ap on a a k SO kan O i La l j Eo a Pl Li p G in gt TO Di A E op oz ko Fre Li a R LJ a le O LIS A ae Ao D7 7 a Emor 145 D 1 in DE faced to the computer via a USB port and are not standard serial and parallel types The same is true of any add on serial and parallel ports provided via a USB port or a PCI card Ports provided in this way do not appear in the PC s input out put map and cannot be addressed directly Sometimes there is a way around this in the form of a utility program provided with the interface This intercepts any instructions to the relevant input output addresses and then sends corresponding instructions to the port on the USB inter face or PCI bus Although this is a slightly round about way of doing things a lack of speed is unlikely to be an issue used this method successfully for some time with add on PCI printer ports and a range of add on circuits Unfortunately a utility of this type is not always included and some USB ser ial and parallel ports do not provide a full implementation of the ports anyway Direct control of a port is only possible if things like the control registers and bidirectional operation of the data lines are fully implemented DLEET Fig 1 This circuit uses eigh
191. llectual cycles based on your date of birth and compar ing today s date The calculator showed a numeric value for each eae you to determine what stage of your P S and cycles you were presently experiencing so that you could predict in horoscope style what pe general state of well being was like Biorhythms were met with increasing scepticism and they have gone the way of all fashions Thanks Alan and Nigel The CZ thread referred to was in the Everything Else section and may be in the Archives by the time you read this Build Your Own Weather Station Measure Wind Speed Measure Wind Direction Measure Temperature Easy Build Kit FREE Software USB or RS232 Optional Humidity Module Optional Pressure Module Weather Starter Kit 59 R5232 Interface E25 USB Interface E29 Humidity Module E39 Pressure Module c49 Rainfall Gauge E59 Prices exclude VAT and delivery Optional Rainfall Gauge Simple 1 wire connection Build and add your own devices For more information manuals and downloads on this and other interesting products see WWW audon co uk mUD Electronics Everyday Practical Electronics August 2007 ARWs past emerges Dear EPE tracked down Alan Winstanleys name from a Google search as a name from my school days My mate Phil and both studied Micro Electronics at GCSE level in the late 80 s in Cornwall and one of us followed one of Alan s Sa for a project but can t rem
192. mally open NO or normally closed NC tamper switches to be used If the tamper switch changes state while the system is armed Q2 is switched on to signal an alarm Three input bits PD1 PD2 and PBO allow user selection of various program options see Table 2 Like the PD3 input these inputs are pulled high internally Therefore installing a jumper shunt changes the respective pin state from a logic high 5V to a logic low OV Power supply The unit can be powered from any 12V DC power supply eg a plugpack and this is applied to the module via CON1 Series diode D1 prevents dam age to all components except Q2 Q3 TO EN ES N Ep E Everyday Practical Electronics August 2007 D2 and D3 in the case of reverse con nected power leads A 10Q resistor and a 16V Zener di ode ZD1 protect the regulator s input from the high voltage transients that typically occur in an automotive envi ronment A 7805 3 terminal regulator REG1 converts the input to a well regulated 5V output with the aid of two 100uF filter capacitors Finally an under voltage sensing circuit based on IC3 holds the micro controller s reset pin low whenever the supply voltage is below about 4 6V This prevents inadvertent writes to the on board EEPROM during power up and power down Construction In order to minimise the module s overall size two components REG1 and D2 are mounted on the bottom copper side of the PC board T
193. mperature controller What need is an article on how to structure code at the high level eg to perform basic software routines like how to read some switches that control the setup menu for calibrating the tempera ture sensors This involves press buttons display text on LCD scroll menu select a number move to next menu item etc need to decide how to read a switch when to pause before the next press how to debounce etc F lowcode takes a lot of the pain out of it but does not actually tell me how to do the global structure of the program M any pees will have a Se menu in them ut can t find a sample flowchart or even commented assembler for one The excellent EPE PIC Tutorial V2 is eo at Assembler level but does not real go into the none level like give the flowcharts behind the anpi programs Although the code is well commented without understanding assembler which don t want to learn it s difficult to reverse engineer the example code into flow charts Of course it would help if EPE con structional articles had in them the flow charts for the software but generally they Printing pfroblems Dear EPE read with interest Richard Sullivan s email in the M ay issue about his printing problems from an old PCB CAD program On a number of occasions I ve dusted off some old and perfectly servicable DOS software only to realise that while it still works fine under the newer versions of Windows
194. mponents are still available I Please charge my Visa Mastercard Amex Diners l before commencing construction of a project from a back issue I Club Maestro I Note Some supplements etc can be downloaded free from the i s Library on the EPE Online website at www epemag com IS i No advertisements are included in Volumes 1 and 2 from Volume 5 A a Fe A iii fi ek aie t eib a i onwards the available relevant software for Interface articles is l Gard N l also included l ar OE EAA IEA C EEA A E EAA AEA E A EA NOANA AEE SEE l l Card Security Code The last 3 digits on or just under the signature strip EXTRA ARTICLES ON ALL VOLUMES BASIC SOLDERING GUIDE Alan Winstanley s internationally acclaimed fully illustrated guide UNDERSTANDING PASSIVE COMPO NENTS Introduction to the basic principles of passive components HOW TO USE INTELLIGENT L C Ds by Julyan llett An utterly practi cal guide to interfacing and programming intelligent liquid crystal display modules PhyzzyB COMPUTERS BONUS ARTICLE 1 Signed and Unsigned Binary Numbers By Clive Max Maxfield and Alvin Brown PhyzzyB COMPUTERS BONUS ARTICLE 2 Creating an Event Counter By Clive Max Maxfield and Alvin Brown INTERGRAPH COMPUTER SYSTEMS 3D GRAPHICS A chapter from Intergraph s book that explains computer graphics technology FROM RUSSIA WITH LOVE by Barry Fox Russian rockets launching American Satellites PC ENGINES by Ernest Fl
195. n Select Tool followed by PicKit2 Then select Debugger fol lowed by Program Our test application is quickly programmed into the demo board and we are ready to start debugging Before we do start debugging take a quick look at the output window in MPLAB An example is shown in Fig 1 which shows some interesting information The line Programming Program M emory indicates the progress of placing our tiny only eight words program into the PIC Further down however is something unex pected Programming Debug Executive W hat s this Debug executive The Debug Executive is a small utility pro gram that is required to be placed inside Build Version Control Find in Files PICkit 2 Initializing PICkit 2 version 0 0 2 16 Found PiCkit 2 Operating System version 2 1 0 arget power not detected Powering from FICkit 2 PICTBFS1 found Rev 0x4 Pickit 2 Ready Frogramming Target 30 05 2007 21 56 53 Erasing Target Frogramming Program Memory 0x0 0x7 verifying Program Memory 0x0 0x7 Programming Debug Executive Ox 1F00 0x1 FFF verifying Debug Executie 0x1 FOO 1 FFF Programming Debug Vector Vertying Debug Vector Programming Configuration Memory Vertying Configuration Memory Debug mode entered DE version 1 0 1 Pickit 2 Ready Fig 1 Download window Everyday Practical Electronics August 2007 your processor by the PICKit2 unit to debug your main program The
196. n 7 0 127mm Grey ribbon cable on a 0 05 1 27mm pitch with a red identifying stripe Supplied by 305mm 1ft or on full 30 5m 100 t reels Size per 305mm per Reel 10 Way 0 10 5 80 14 Way A 16 Way 20 Way 26 Way 34 Way 40 Way 50 Way 60 Way IDC Crimp tool CAT 5e Networking UTP Cable Conforms to CAT5E 100MHz standard ETA verified TIA EIA 568 B 2 305m Box 45 31 100m Reel 22 28 exc carriage RJ45 Outlet Kit Backing Box 2 Gang Plate RJ45 Module Blank Module Coloured id inserts 2 99ea 2 42 10 Tools Plastic punch down tool amp cable stripper Professional punch down IDC amp trim tool Outlets CAT5e Outlet Module 1Gang Plate 2 Mods 2 Gang Plate 4 Mods Module Blank 1 Module Blank 2 Module Blank a Other keystone outlets switches amp accessories avail able Patch amp Cross over leads from 0 50 Prices Exclude Vat 17 ESR Electronic Components PLEASE ADD CARRIAGE amp VAT TO ALL ORDERS Wy SY EVERYDAY PRACTICAL Editorial Offices EVERYDAY PRACTICAL ELECTRONICS EDITORIAL Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Phone 01202 873872 Fax 01202 874562 Email enquiries epemag wimborne co uk Web Site www epemag co uk EPE Online downloadable version of EPE www epemag com EPE Online Shop www epemag wimborne co uk shopdoor htm THE UK s No 1 MAGAZINE FOR ELECT
197. n under All Jaycar kits are supplied with specified board components quality fibreglass tinned PCBs and have clear English instructions Watch this space for future featured kits RFID Security Module Receiver Kit KC 5393 28 95 post amp packing Radio Frequency Identity RFID is a contact free method of controlling an event such as a door strike or alarm etc An RFID Tag transmits a unique code when energised by the receiver s magnetic field As long as a pre programmed tag is recognised by the receiver access is granted This module provides normally open and normally closed relay contacts for flexibility It works with all EM 4001 compliant RFID a Kit supplied with PCB tag and all electronic components SMS Controller Module Kit KC 5400 15 95 post amp packing Control appliances or receive alert notification from anywhere By sending plain text messages this kit will allow you to control up to eight devices It can also monitor four digital inputs It works with old Nokia handsets such as the 5110 6110 3210 and 3310 which can be bought inexpensively if you do not already own one Kit supplied with PCB pre programmed microcontroller and all electronics components with clear English instructions Requires a Nokia data cable which can be readily found in mobile phone accessory stores E 10A 12VDC Motor Speed Controller KC 5225 7 75 post amp packing Use this kit for controlling 12V DC motors in cars su
198. ng operation Customise presentations using TINA s advanced drawing tools to control text fonts axes line width colour and layout You can create and print documents directly inside TINA or cut and paste your results into your favourite word procesing or DTP package TINA includes the following Virtual Instruments Oscilloscope Function Generator Multimeter Signal Analyser Bode Plotter Network Analyser Spectrum Analyser Logic Analyser Digital Signal Generator XY Recorder Flowcode V3 Hobbyist Student For details on Flowcode see the previous page This offer gives you two seperate CD ROMs in DVD style cases the software will need registering FREE with Designsoft TINA and Matrix Multimedia Flowcode details are given within the packages Get TINA Flowcode for a total of just 50 including VAT and postage PROJECT DESIGN WITH CROCODILE TECHNOLOGY An Interactive Guide to Circuit Design An interactive CD ROM to guide you through the process of circuit design Choose from an extensive range of input process and output modules including CMOS Logic Op Amps PIC PICAXE Remote Control Modules IR and Radio Transistors Thyristors Relays and much more Click Data for a complete guide to the pin layouts of i c s transistors etc Click More Information for detailed background information with many animated diagrams Nearly all the circuits can be instantly simulated in Crocodile Technology not included
199. ng you through the fascinating world of computer design and you ll have a few chuckles if not belly laughs along the way In addition to over 200 500 pages megabytes of mega cool multimedia the CD ROM con tains a virtual microcomputer simulating the mother board and standard computer peripherals in an extremely realistic manner In addition to a wealth of technical information myriad nuggets of trivia and hun dreds of carefully drawn illustrations the CD ROM con tains a set of lab experiments for the virtual microcom puter that let you recreate the experiences of early com puter pioneers If you re the slightest bit interested in the inner workings of computers then don t dare to miss this Over 800 pages in Adobe Acrobat format CD ROM Order code BEB2 CD ROM 21 95 GETTING THE MOST FROM YOUR MULTIMETER R A Penfold This book is primarily aimed at beginners and those of lim ited experience of electronics Chapter 1 covers the basics of analogue and digital multimeters discussing the rela tive merits and the limitations of the two types In Chapter 2 various methods of component checking are described including tests for transistors thyristors resistors capaci tors 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 experience is assumed Using these simple componen
200. nge of 150 480 C ow voltage Iron with Silicone cable Supply 240V Iron 24V 48W Model 167 570 55 61 Digital Multimeter Model 121 120 Price 11 47 A highly featured digital multitester for professiona use Offers 30 ranges and 8 functions including temper ature capacitance diode continuity and hFE measure ment Large 3 5 digit LCD display with automatic po larity indicator Supplied with shrouded test leads K type temperature probe and shock proof rubber holster Technical Specifications DC voltage 200mV 1000V 0 5 AC volts 2V 700V 0 8 DC current 2mA 20A 1 2 AC current 200mA 20A 1 8 esistance 200 Ohms 20M Ohms 0 8 Capacitance 2000pF 20uF nee Temperature 0 C 1000 C 1 5 VE 20kHz 1 Max display 1999 Power supply 9V PP3 battery Dimensions 88 x 173 x 40 mm lt A oe seeceeues gt A high quality scratch resistant tube provides illumination PCB Production Processing Equipment We carry a large range of the photographic amp chemical pe equipment for PCB production a full list with ull technical specifications is available in our catalogue or vist our web site UV Exposure units 2 x 8W Tubes 6 min timer 229 x 159mm working area Model 332 002 98 75 4 x 15W Tubes 7 min timer 330 x 260mm working area odel 332 004 209 48 Chemical Processing Low cost plastic tray 7 30 Process tanks
201. now available for free download from www eptsoft com StudentHobbyist electronics html This is the complete package without any install or time restrictions Just a few weeks ago eptsoft placed their electronics software in the public domain for free download previously selling for hun dreds of pounds T here has been an enormous response M any thousands were downloaded world wide in the first few days from hun dreds of freeware sites Designed to provide a focal point for find ing electronics components and equipment suppliers this is not like any normal internet advertising but uses fully installed software with a unique web browser that links directly to advertisers web sites Orange revenue stream When WAP was launched we promised the next wonderful new world People just used SM S text mes Saging instead They didn t want what we d spent all that money on WAP and 3G People used good old SMS Thank goodness they did because it generated the revenue It saved us But we hadn t antici pated it In similar vein Jeremy Ling CEO Philips Consumer Electronics told how he had joined Philips a year ago with no expe rience of consumer electronics He arranged to spend several days working as a salesman in Comet to get a feel for what was needed more simplicity Do you know what the retail return rate is for wireless routers Ling asked the audi ence 10 20 30 no 40 of all home wireless network
202. nput lines The circuit of Fig 2 uses the PE Paper Empty input at pin 12 of the printer port to enable an additional set of eight switches to be monitored The PE input is read at bit 4 of the Status register Operation of the circuit and the scan ning process are much the same as before but the software has to check the States of both inputs each time a new value is sent to the output port While this method of reading switches may seem rather old fashioned it has the big advantage of being very cheap to implement The only components req uired apart from the switches are inexpensive diodes and resistors The cost of implementing a system of this type is therefore negligible It also has the advantage of being entirely passive thus avoiding problems with power sup plies The system can be expanded to accommodate a larger number of switch es but there are probably better ways of doing things where dozens of switches are involved Conventionally this type of thing is handled by a dedicated chip or a microcontroller based interface that han dles the reading process simplifying the software and reducing the loading placed on the PC Fig 3 The circuits of Fig 1 and Fig 2 can be driven successfully by some logic outputs but ideally an open col lector output stage should be used The collector c and emitter e of the output transistor TR1 are connected in place of the switch Lopical turn on Although designed t
203. o program sources such as CD player MP3 player and FM AM tuner and has front panel LEDs to indicate which source has been selected The other controls are Bass Treble Volume and Balance At the rear there are RCA phono line inputs binding posts for the speaker connections a finned heatsink and a socket for the plugpack supply jack As part of the final checking of this 48 amplifier one of our staff members took it home for a blast on his large stereo system His daughter was so impressed with the performance from such a tiny package that she wanted it straight away We thought that was a pretty good endorsement The reason why it packs such a punch is that it can deliver around 17 watts music power per channel into 4 ohm loudspeakers In a typical room with reasonably efficient speak ers that s enough to blast you out of your seat And did we say it s tiny It measures just 225mm wide 40mm high and 165mm deep including the knobs and rear heatsink It s also pretty quiet and its other performance parameters are pretty good as well considering that we have kept a very tight rein on the overall cost of the design One reason it performs so well is that it is based on the same National Semiconductor LM1875T 20W audio amplifier IC used in the Students Amp published in the April 2007 issue This IC has inbuilt thermal protection so that even if you abuse it or short out its output it won t be damag
204. o read switches circuits of this type will often work when driven by logic outputs However the circuit should ideally be driven from open collector outputs when used to read some form of logic circuit The simple open collector inverter circuit of Fig 3 works well in this appli cation Transistor TR1 operates as a basic common emitter switch that is turned on when the input is taken high The emitter e and collector c termi nals of TR1 are connected in place of the pushbutton switch and a separate Switching circuit is needed to replace each mechanical switch In the next Interface article the software side of things will be considered in detail together with a simple application 61 Product Review E Blocks a and By Robert Penfold BLOCKS are dual purpose electron FE modules that in one role enable users to learn about electronics and PIC programming For experienced users they provide a means of quickly building and testing PIC ARM AVR or CPLD based designs The E Block concept is very sim ple and it is based on programming mod ules that can also be used as the basis of prototype units More than one programmer is available but the one featured here is the more advanced PIC Multi programmer Fig l This unit has sockets that can accommodate a wide range of PIC processors having from eight to 40 pins The way the sockets are arranged precludes the use of ZIF sockets unless an extra turned pin
205. oards CADPACK is made up of three separate software modules These are restricted 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 6 MECHATRONICS 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 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 8 Interactive
206. of mechanical products many of which are hard to find elsewhere Bearings from 1mm to 30mm bore Plastic and steel pulleys plastic and steel gears from MOD 0 5 to MOD 2 0 Steel chain sprockets in 6 amp 8mm 3 8 bolts from M2 to M12 springs clips amp Pins Wide amp 1 2 pitch Silver steel ENZ4T steel collets amp shaft couplings Nuts and range of engineering ma terials including aluminium 6082 T6 to 12mm thick brass tube rod sheet etc Polycarbonate sheet from 1mm to 12mm thick PVC sheet polymorph etc Wheels from 9mm to 250mm diameter We believe this to be the lowest retail priced 4 channel 40MHz FM radio control set in the UK The set includes the transmitter receiver and crystal pair from just 34 95 Upgrade options available Sample pricing eTransmitter receiver and xtals 34 95 As above but with a set of 8 AA batteries 35 95 or with a set of 8 AA rechargeable batteries 41 49 eAdd a fast charger for an additional 11 46 Glass automotive and maxi fuses from 1A to 100A fuse holders cable from 0 5mm to 16mm Pre stripped wire kits for breadboards Connectors from 5A to 300A wide range of crimp connectors sili in 100 s or in kits Circuit breakers from 3A to 30A Cable ties tie bases spiral wrap and heatshrink 1 2 to 101 6mm diameter All prices include VAT Whilst we are an internet company we do have a shop
207. omers to manufacture under license The product range currently consists of the following standard back planes with 4 6 or 8 slots controller modules for stepper and DC motors controller modules for valves and solenoids pressure control flow control etc a USB interface to allow connection to a PC etc various I O modules Parallel I O relay output and Analogue I O modules The MonCon range has been designed with flexibility in mind Backplanes and modules to meet your requirements can generally be designed amp supplied within 6 weeks of receiving a full specification ue yi Compact Control Design Limited 77 Woolston Avenue Congleton Cheshire CW12 3ED UK Tel 44 01260 281694 Fax 44 01260 501196 E mail salesQcompactcontrol co uk CAN 1 Board Interface CAN via MCP2551 CANSPI Board Make CAN network with SPI interface RS485 Board Connect devices into RS 485 network Serial Ethernet Make ethernet network with SPI Interface ENC28J60 IrDA2 Board Irda2 serves as wireless RS232 communi cation between two MCUs Storage RTC CF Board Easy way to use Compact flash in your design MMC SD Board Easy way to use MMC and SD cards in your design EEPROM Board Serial EEPROM board via 12C interface RTC Board PCF8583 RTC with battery backup Aqu Measurement ADC Board 12 bit analog to digital converter ADC with 4 inputs DAC Board
208. on Programming style Before we investigate that final problem a quick diversion about programming style It s considered good practice when writ ing code to first write comments describ ing what you intended to do and then write the code to do it afterwards This way the comments are always an accurate reflection of your original intention and can help you remember later on when fin ishing off a piece of code what you origi nally wanted it to do So for example when writing a simple program to turn on some LEDs on a port your source code would start off as set PORT D to outputs Turn on alternate LEDs and then you fill in the code afterwards Set PORTD to outputs bsf STATUS RPO clrf TRISD bcf STATUS RPO Turn on alternate LE D s moviw OxAA movwf PORTD The golden rule of comments is to always state what you intend the code to do not a literal explanation of what you are going to do For example in the previous section of code if you had written the comment Set PORTD to OxAA that comment says nothing about why you are doing it Always use comments that describe what you intend the code to do It will make debugging and reusing the code at a later stage much simpler Don t state the obvious An extension to this commenting rule is to place markers in the source file to indi cate where a piece of code needs to be written or finished off at a later date TODO disableADC inputs You c
209. on but when it is it s well worth taking Finishing off We will finish off this month with a little brain teaser In some projects especially games a source of random numbers is required to give an interesting variation in the choices the program takes In a previ ous Pic n Mix article we discussed the design of a pseudo random number gener ator in software that can give a series a random like byte values but this is not the only way to do it Can you think of another way to gener ate useful random numbers on a PIC either through software hardware or a combina tion of both No prizes available but an honorary mention in a later article for the most inter esting idea Submissions by email to mike hib bett gmail com or to EPE EVERYDAY PRACTICAL ELECTRONICS NEWSAGENTS ORDER FORM Please reserve deliver a copy of Everyday Practical Electronics for me each month Name and Address Everyday Practical Electronics is published on the second Thursday of each month and distributed S O R by SEYMOUR Make sure of your copy each month cut out or photocopy this form fill it in and hand it to your newsagent Everyday Practical Electronics August 2007 21 Open doors amp control security systems with this RFID ss Security Q Module Tired of fumbling in the dark for your keys Can t find the keyhole on a moonless night Or perhaps you re just irritated by having to punch in a code each t
210. on tools for SD MMC UDP Ethernet and USB EEPROM editor programming mode management etc Each compiler has many routines and examples such as EEPROM FLASH and MMC reading writing SD and CF cards writing character and graphics on LCDs manipulation of push buttons 4x4 keyboard and PS 2 keyboard input generation of signals and sounds character string manipulation mathematical calculations I2C SPI RS232 CAN USB RS485 and OneWire communications Manchester coding man agement logical and numerical conversion PWM signals interrupts etc The CD ROM contains many already written and tested programs to use with our development boards mikroElektronika manufactures competitive development systems We deliver our products across the globe and our satisfied customers are the best guarantee of our first rate service The company is an official consultant on the PIC microcontrollers and the third party partner of Microchip company We are also an official consultant and third party partner of Cypress Semiconductors since 2002 and official consultant of Philips Electronics company as well http www mikroe com en distributors Find your distributor UK USA Germany Japan France Spain Greece Turkey Italy Slovenia Croatia Macedonia Pakistan Malaysia Austria Taiwan Switzerland Lebanon Syria Egypt Portugal Uni DS 3 Development Board with on board USB 2 0 programmer The system supports PIC AVR 8051 ARM and
211. on version is available The USB M ulti program mer costs 55 00 plus VAT Example prices for the E Blocks are 10 00 plus VAT for the LED board and 15 00 plus VAT for the LCD board Radio Bygones The leading UK magazine for vintage radio enthusiasts It was not possible to check the system using a large number of programs but those that were tried all compiled correct ly if a little slowly and were transferred to the PIC chip without problems Documentation Printed documentation is more or less non existent but there is a mini CD ROM that has manuals in PDF format for the full range of E Blocks M ost PCs already have the A dobe Acrobat Reader needed to display and print the PDF documents but this program is included on the disc The manuals are brief but well produced and each one includes the circuit diagram for the relevant E Block There is also at least one Flowcode test pro gram for each E Block making it easy to check that everything is working properly The Flowcode program itself has 28 exam ple programs that are installed together with the Flowcode program These do not really constitute a tutorial but someone with a basic knowledge of programming should be able to learn a great deal by running these as simula tions and in the single step mode There is the usual Help system that cov ers the general processes of using the pro gram from loading and saving programs to more advanced topic
212. ooster double sided x Telescope Interface Smart Slave Flash APR 06 Programmable Continuity Tester PortaPAL Microphone Board Auxilary Board Main Board Charger Board Omni Pendulum Smart Card Reader Programmer MAY 06 LED Lighting For Your Car set of 15 boards Digital Reaction Timer Poor Man s Metal Locator JUN 06 Digital Instrument Display for Cars Micro Board Display Board Widgy Box Phone Ring amp Test Sudoku Unit JUL 06 PC Power Monitor Home Theatre Sound Level Checker AUG 06 Adjustable DC DC Converter For Cars Telephone Dialler For Buglar Alarms High Intensity Torch Low Cost 50MHz Frequency Meter Version 1 Version 2 Version 3 Smart Mixture Display for your Car Water Level Gauge Sensor Display Fridge Door Open Alarm OCT 06 Linear Supply For 1W Star LEDs Pair Through Glass Alarm Quick Brake Studio 350 Power Amplifier Micropower Battery Protector x Giant LED Message Display Master Slave NOV 06 Lapel Microphone Adaptor DEC 06 RGB To Component Video Converter double sided USB Power Injector Mind Trainer 78 PROJECT TITLE Balanced Microphone Preamp JAN 07 599 6 82 High Efficiency Power Supply for 1W Star LEDs 600 6 19 Jumping Spider 601 5 7i x Programmable Robot FEB 07 Courtesy Light Delay Deep Cycle Battery Charger Power Board Control Board Display Board PIC Digit
213. osi amp casy to assemlle tor cheap ICs a 5V regulator a couple of DIP switches to set up the data and control bit lines six LEDs for status indication a pushbutton switch to produce strobe pulses and a handful of other components It all fits on a small PC board measur ing 113 x 61mm and runs from a 9V DC plugpack The maximum current drain with all LEDs on is just 58mA How it works Refer now to Fig 1 for the circuit details The simulated port interface is provided via CON1 which dupli cates the DB25 female connector used to provide the standard printer port on a PC Pins 2 to 9 are used for the main data bus DATA O to 7 to the printer These pins are connected to a very simple data input circuit which uses eight 10kQ pull up resistors and an 8 way DIP switch S3 Each pole of S3 is simply connected between one of the data lines and ground when a switch is closed that line is pulled to ground OV Everyday Practical Electronics August 2007 STROBE Ok 10k STROBE MODE ON CONTIN OFF PULSE 3300 aa LPT INTERFACE IC1 74HC132 CON IC2 7AHCO4 IC2d DB25F 1 STROBE 1N4148 A K j 1N4004 A A K 3 DATA 1 ee a DATA 2 w I 1 p aaa me Le i ye LI DATA 6 an Dd f ahabofofef ef ofal se DATA BITS SIL 8 x 10k OFF H PERE LEDS 1 5 ee ie a na te IC2a f b e c NOT USED Tt n It h
214. other peripherals without a PC imas Jorm m INGENUITY UNLIMITED sharing your ideas with others 70 Atmospheric Change Monitor Series and Features TECHNO TALK by Mark Nelson 10 Two Birds With One Stone PIC N MIX by Mike Hibbett 20 Starting a new PIC project some guidance USING MPLAB PART 3 by Mike Hibbett 30 Debugging CIRCUIT SURGERY by lan Bell 38 Linear Voltage Regulators and Capacitors Part 2 THE POWER OF MECHATRONICS PART 3 by Darren Wenn 42 Stepping Up a Gear INTERFACE by Robert Penfold 60 Problems of Setting Parallel Port Outputs to Inputs E BLOCKS AND FLOWCODE 3 REVIEWED by Robert Penfold 62 NET WORK by Alan Winstanley 74 Virtually there Street wise Regulars and Services EDITORIAL 7 NEWS Barry Fox highlights technology s leading edge 8 Plus everyday news from the world of electronics CD ROMS FOR ELECTRONICS 34 A wide range of CD ROMs for hobbyists students and engineers SUBSCRIBE TO EPE and save money 37 BACK ISSUES Did you miss these 46 READOUT John Becker addresses general points arising 72 DIRECT BOOK SERVICE 75 A wide range of technical books available by mail order plus more CD ROMs EPE PCB SERVICE 78 PCBs for EPE projects Wimborne Publishing Ltd 2007 Copyright in all drawings photographs and articles published in ADVERTISERS INDEX 80 EVERYDAY PRACTICAL ELECTRONICS is fully protected and reproduction or imitations in whole or in part are expressly forbidden Our S
215. ou need to be notified immediately when an event has ocurred FLEXITIMER This multi purpose timer is much more flexible than previous designs You can program it for a single time period ranging from one second to 99 minutes and 59 seconds or a sequence of two such independently programmed time periods or up to 99 cycles of one or two time periods It s also easy to program DEAD SIMPLE USB BREAKOUT BOX Check you are not overloading the USB port V2 PC Scope Part 2 The software Using MPLAB Part 4 SEPTEMBER 07 ISSUE ON SALE AUGUST 9 ADVERTISERS INDEX AGAR CIRCUITS AUDON ELECTRONICS BETA LAYOUT BULL GROUP COMPACT CONTROL DESIGN DISPLAY ELECTRONICS ESR ELECTRONIC COMPONENTS JAYCAR ELECTRONICS JPG ELECTRONICS LABCENTER LASER BUSINESS SYSTEMS MAGENTA ELECTRONICS MIKROELEKTRONIKA NURVE NETWORKS LLC PALTRONIX PEAK ELECTRONIC DESIGN PICO TECHNOLOGY QUASAR ELECTRONICS SCANTOOL SHERWOOD ELECTRONICS STEWART OF READING TECHNOBOTS ADVERTISEMENT OFFICES SEQUOIA HOUSE 398A RINGWOOD ROAD FERNDOWN DORSET BH22 9AU PHONE 01202 873872 FAX 01202 874562 EMAIL epeads wimborne co uk For Editorial address and phone numbers see page 7 Everyday Practical Electronics ISSN 0262 3617 is published monthly 12 times per year by Wimborne Publishing Ltd USA agent USACAN Media Dist Srv Corp at 26 Power Dam Way Suite S1 S3 Plattsburgh NY 12901 Periodicals postage paid at Plattsburgh NY and at additional
216. our variable size the EQU directive simply Substitutes any reference to the word size with the numeric value 0x23 This is all well and good but there is nothing to stop you accidentally creating another variable at the same address The problem is that you are being left responsible for assigning each variable to an absolute address Human error naturally steps in from time to time Fortunately there is a solution using the directive CBLOCK which is used to define a block of constants Using it does not occupy any space in code or RAM memory it simply creates an ordered list of variable to value relationships that is remembered by MPLAB should you choose to use the variable names in your source files At the end of the day your shex program file contains just absolute addresses so using absolute numbers 0x23 EQU generated names e g size or areference from a CBLOCK definition will make no difference to the content of your program but it could make a differ ence to the bugs you Introduce CBLOCK usage Using CBLOCK directives is quite straight forward The fine details can be found in MPLAB s help menu but its use is simple to describe It uses two directives CBLOCK at the beginning of the list of variables and ENDC at the end Following the word CBLOCK you specify the starting address value CBLOCK 0x23 Between CBLOCK and ENDC you need to specify the names that you wan
217. ow is applied to pin 1 of IC1a As a result the flipflop is triggered into switching states ie pin 3 goes high and pin 11 goes low This marks the start of the strobe pulse When pin 3 goes high it removes the forward bias on D1 and so it can no longer pull pins 4 and 5 low Asa result the associated 390pF capacitor begins charging via a 10kQ resistor After about 2us the voltage on pins 4 and 5 rises high enough to switch IC1b When that happens pin 6 of IC1b goes low and because this pin is connected to pin 13 of IC1d this trig gers the flipflop into switching state again As a result pin 3 switches low and pin 11 switches high bringing the strobe pulse to an end Note that this all takes place only if switch S2d is open That s because if S2d is closed it holds both inputs of IC1b low permanently and so prevents it from resetting the flipflop Basically S2d allows you either to produce strobe pulses using S1 when S2d is open or to hold the strobe line down continuously after pressing S1 This second mode is handy for troubleshooting Status LEDs Most of the remaining circuitry in the simulator is used to drive LEDs 1 to 5 These are used to monitor the printer status lines of the parallel port Acknowledge pin 10 Busy Ready bar pin 11 Paper Out pin 12 Select In pin 13 and Error pin 15 As shown in Fig 1 the LEDs are driven by inverters IC2a IC2b IC2c IC2e and IC2f all part of a
218. owed by a would be intruder they may be able to add their own tag to the sys tem and return the master without your knowledge Installation and wiring The low operating frequency of this system enables operation through non metallic materials This means that it can be installed behind walls and inside consoles for example The main limitation here is the maximum operating range Our prototype operates at up to 95mm although large metal objects nearby tend to reduce this range When in doubt test before reaching for your hammer and chisel As previously mentioned the module is also small enough to fit behind a stand ard electrical wall plate or similar Fig 6 shows several basic hook up schemes covering both stand alone operation and use with a more com prehensive alarm system It s up to you 28 Where To Get The Parts 1 The ID 12 RFID module and Tags are available from Mannings RFID in the UK www rfidshop com Tel 01704 538202 2 Electric door strikes are available from security companies and larger DIY stores to choose the scheme that best suits your application If using the door strike option the ground return wire back to battery negative should be run using heavy duty cable especially for long runs If using multi core alarm cable combine two cores in parallel to achieve similar results A separate wire from the bat tery positive to the door strike solenoid is al
219. owing at a double digit rate annually In office situations PoE deliv ering around 13W at 48V enables users to deploy standalone phones for Voice over Internet Protocol VoIP digital CCTV cam eras smartcard readers and low power wire less repeaters without the need for separate wall wart power supplies According to Alison Smith product marketing manager at IC maker Linear Technology PoE is also gaining popularity for small business and home office networks 10 PoE Plus A harmonised standard called PoE Plus is expected to give the notion of power over data cabling a boost when it is ratified in 2008 or 2009 The goal for the new standard IS to increase maximum power rating to at least 30W to provide greater power for evolving applications such as motorized net work cameras supporting pan tilt and zoom IP telephony videophones RFID readers and access control systems point of sale and information kiosks and eventually laptops or palmtop computers So says cable prod ucts manufacturer Panduit which also notes that PoE Plus will likely support delivery over two cable pairs for powering devices up to 30W and four pair power for power greater than 30W So now from PoE to PoO which is set to become even more of a disruptive technolo gy PoO is no childish frivolity but deadly serious delivering as it does Power over Optical fibre Now optical fibres as you doubtless know are made of silica glass or
220. p toys tor boys Visit the website Www danielsden co uk ERE VERYDAY P RACTICAL Dreamland Hanger 18 Bargain Basement x ELECTRONICS Get your magazine instantly anywhere in the world buy and download from the web VISIT OUR ONLINE io konse TAKE A LOOK A FREE SHOP TO ORDER SE ISSUE IS AVAILABLE SUBSCRIPTIONS AND 3 a at WHS 6 99 e RENEWALS BACK A one year subscription ISSUES CDROMS 12 issues costs just BOOKS PCBS AND THIS SPACE 15 99 US isi COULD BE YOURS Back issues are also www epemag co uk FOR JUST 50 available Contact Stewart on 01202 873872 a Tr E stewart kearn wimborne co uk a felt iftte Everyday Practical Electronics August 2007 79 Europe s Largest Surplus Store 20 000 000 Items on line NOW New items added dail Established for over 25 years UK company Display Electronics prides itself on offering a massive range of electronic and associated electro mechanical equipment and parts to the Hobbyist Educational and Industrial user Many current and obsolete hard to get parts are available from our vast stocks which include 6 000 000 Semiconductors 5 000 Power Supplies 25 000 Electric Motors 10 000 Connectors 100 000 Relays 8 Contactors 2000 Rack Cabinets 8 Accessories 4000 Items of Test Equipment 5000 Hard Disk Drives Display Electronics 29 35 Osborne Road Thornton Heath Surrey UK CR7 8PD Telephone 44 020 8653 3333 Fax
221. p ate Tata ARTICLES on restoration and repair history circuit techniques personalities reminiscences and just plain nostalgia you ll find them all Plus features on museums and private collections and a full colour photo feature in every issue Irs MOSTLY about valves of course but solid state whether of the coherer and spark gap variety or early transistors also has a place FROM THE DAYS of Maxwell Hertz Lodge and Marconi to what was the state of the art just a few short years ago THERE IS ALSO a selection of free readers For Sale and Wanted advertisements in every issue Radio Bygones covers it all THE MAGAZINE is published six times a year and is only available by postal subscription It is not available at newsagents TO TAKE OUT a subscription or to order a sample copy please contact Rapiro BYGONES Wimborne Publishing Ltd Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Tel 01202 873872 Fax 01202 874562 Web sites www radiobygones co uk www radiobygones com Everyday Practical Electronics August 2007 65 The LPT Simulator will take you next to no time to build Note that the final version differs slightly from this prototype 1G It TZ T3 l 3 es Ss l nn Printer port hardware simula Do you need to test printers or other items of equipment that connect to a PC s parallel printer port This low cost easy to build circuit will l
222. panied by a stamped self addressed envelope or a self addressed envelope and international reply coupons We are not able to answer techni cal queries on the phone PROJ ECTS AND CIRCUITS All reasonable precautions are taken to ensure that the advice and data given to readers is reli able We cannot however guarantee it and we cannot accept legal responsibility for it A number of projects and circuits published in EPE employ voltages that can be lethal You should not build test modify or renovate any item of mains powered equipment unless you fully understand the safety aspects involved and you use an RCD adaptor COMPONENT SUPPLIES We do not supply electronic components or kits for building the projects featured these can be supplied by advertisers We advise readers to check that all parts are still available before commencing any pro ject 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 bona fide the magazine and its publishers cannot give any undertak ings in respect of statements or claims made by advertisers whether these advertisements 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
223. patch board that has a large area containing double sided pads but no solderless breadboard With some real world circuits it might be possible to use no hardware other than the basic PIC circuit and two or three E Blocks Being realistic about matters many practical circuits will require something out of the ordinary that cannot be han dled by one of the E Blocks Even in these cases it is likely that it will be possible to imple ment most of the hardware via Everyday Practical Electronics August 2007 E Blocks such as the LCD keypad and relay boards with the awkward parts being provided via a prototyping E Block or the user s own prototype board The E Blocks therefore provide a relatively quick and easy means of prototyping any circuit that is not completely out of the ordinary The E Blocks are not cased a plastic cover is available but all including the programmers are fitted with rubber feet so that they can be used without scratch ing the worktop Some are passive but most require a power source Power is not available from the 9 way connectors which only carry the ground connection and up to eight data lines However 5V and 14V supplies are available from the programmer Software Obviously some software is needed in order to utilise the programmer and the supplied software offers two approaches The conventional approach is accommo dated by a program called PPP which will run under any version o
224. pin 1 end towards the closest edge of the board When inserting the microcontroller IC1 in the socket note that it also has a notched end that must line up with the notch in the socket 2 Before installing the crystal X1 bend its leads at 90 about 2mm from the body Position it flat on the PC board surface before soldering the leads That done its metal can should be affixed to the board with a blob of hot melt glue contact adhesive or similar 3 Be careful not to confuse the BC337 transistors Q1 and Q2 with the MC34064 5 under voltage sensor DOOR STRIKE ALARM ARMED TAMPER SWITCH NO LINK WIRE k i IC3 as both devices are supplied in TO 92 packages The flat sides of these devices must go in as shown For transistor Q3 the metallised col lector side must face the power input connector CON1 4 The two 100uF capacitors and piezo buzzer WD1 are polarised de vices and must be inserted with their positive leads aligned as indicated by the markings on the overlay 5 The mounting arrangements for LED1 will vary depending on the chosen enclosure If its lead length is sufficient for it to extend all the way through the front panel it can be sol dered directly in position Alternatively it can be attached to the board via short lengths of light duty hook up wire and glued into place in the enclosure Twist the wires tightly together to minimise noise pickup from the ID 1
225. pment Smoothing capacitors are on the input side of the regulator whereas the Capacitor to ensure stability is on the out put side We looked at some of the basics of feedback in the context of op amp cir cuits in which negative feedback is applied to very high gain op amps to pro duce amplifier circuits with much lower gain but with many other desirable prop erties If the op amp has a gain of A and the feedback is a fraction 6 then the value BA is called the loop gain If the gain of the op amp is sufficiently large then the gain of the circuit is 1 6 This is very use ful because the amplifier circuit s gain can be set using only resistor values which set and is effectively indepen dent of the op amp s gain Instability However negative feedback comes at the price of possible instability As the signal frequency increases the phase shift pro duced by the circuit often tends to increase and at some point may reach 1802 This is equivalent to inverting the signal at which point any negative feedback becomes posi tive feedback and oscillation may result To prevent this unwanted oscillation we have to make sure that as frequency increases the phase shift of the loop gain remains less than 180 until the magnitude of the loop gain is less than one Alternatively we can look at this as mak ing sure the gain drops below 1 before the phase shift hits 180 as frequency is increased We can characterise how much s
226. ponents and the electronic principles Req s 3 x AA batts 13 ref BET 1801 This 40 in 1 electronic kit includes an introduction to electrical and electronic technology It provides conpo nents that can be used in making basic digital logic cir cuits then progresses to using Integrated circuits to make and test a variety of digital circuits including Flip Flops and Counters Req s 4 x AA batteries 17 ref BET1804 The 75 in 1 electronic kit includes an nintroduction to electrical and electronic technology It provides conpo nents that can be used to make and test a wide variety of experiments including Water Sensors Logic Circuits and Oscillators The kit then progresses to the use of an inter grated circuit to produce digital voice and sound record ing experiments such as Morning Call and Burglar Alarm Requires 3 x AA batteries 20 ref BET1806 www slips co uk ISSN 0262 3617 PROJECTS THEORY NEWS COMMENT POPULAR FEATURES VOL 36 No 8 AUGUST 2007 www epemag co uk EPE Online www epemag com Li LI LI Je il Projects and Circuits i ae V2 PC SCOPE PART 1 by John Becker 12 Eea di A PIC and PC controlled hobbyist oscilloscope se a RFID SECURITY MODULE by Peter Smith 22 Contactless key system lt a EP TWINTEN STEREO AMPLIFIER by Jim Rowe and Peter Smith 48 k Easy to build with surprising performance T l PRINTER PORT HARDWARE SIMULATOR by Jim Rowe 66 ra g Tests printers and
227. r cards accepted Mail Order Only www magenta2000 co uk sales magenta2000 co uk Laser 5 Why tolerate when you can automate lt C Bus Shop C Bus and C Bus Wireless WwwWww cbhus shop com Tel 44 0 20 6441 9788 Fax 44 0 20 6449 0430 Email infoi ilaser com 16 Garthland Drive EN5 388 Stene Steaua Circuits PCA DESIGN amp MANUFACTURE far both the Ho byist and Professional www stewart of reading co uk Check out our website 1 000s of items in stock BEEE i ki tiie Ii eo PEStest ef ff 1 pi PM3082 195 DIGITISING STORAGE OSCILLOSCOPES HP 54616B Digitising 500MHZ 2GS S 2 TEKTRONIX TDS520 Digitising 500MHZ 500MS S 2 Channel TEKTRONIX TDS360 Digitising 200MHZ 1GS S 2 Channel Probes Ops Manual Pouch amp Front Cover TEKTRONIX TDS224 Digitising 100MHZ 4 Channel FLUKE 97 Dual Trace 50MHZ 25 MS S OSCILLOSCOPES TEKTRONIX 2465B 4 Channel 400MHZ Delay Cursors etc incl Tek Probes TEKTRONIX 2445A 4 Channel 150MHZ Delay Sweep Cursor etc GOULD OS300 Dual Trace 20MHZ PHILIPS PM3217 Dual Trace 50MHZ Delay Sweep FARNELL DTV12 14 Dual Trace 12MHZ TEKTRONIX P6139A 100MHZ Probes Unused STEWART of READING 17A King Street Mortimer Near Reading RG7 3RS Telephone 0118 933 1111 Fax 0118 933 2375 www stewart of reading co uk 9am 5 00pm Monday to Friday MARCONI 2024 1 250 to 1 500 HP 8563A 9KHZ 22GHZ Synthesised HP 8560A 50HZ 2 9GHZ Synthesised Various opts
228. rcuit IC13 also drops it to 5V but for use by the analogue chips IC14 inverts the 9V to roughly 9V which is then reduced to 5V by IC15 This voltage is also for analogue circuit use PC SERIAL 9 PIN FEMALE Fig 4 Serial interface circuit diagram 15 16 DIG TRIG Construction 5V DIG There are two printed circuit boards PCBs for this design one for the master control circuit and the other for the analogue channels Their assembly and copper tracking details are shown in Fig 6 and Fig 7 respectively They are available from the EPE OV DIG 5V ANA PCB Service codes 629 Master and 630 Analogue Ready programmed PICs are available from Magenta Electron OV ANA ics www magenta2000 co uk see their ad in this issue Assemble both in the usual order of ascending component size noting that some link wires go beneath the IC socket positions Use sockets for all dual in line DIL ICs but do not insert those ICs until the correctness of the three power line aspects has been proved Correctly observe the polarity of all polarised components i e diodes electrolytic capacitors and ICs A 9 pin D type female connector is required for SK4 The type of socket used for SK1 if at all is immaterial and should be chosen Fig 6 Component and track layout details for the master IN Rw OUT POWER ANA control PCB l Dau ER BA tov OV OV 5V 5V N Y pei e IC12 13 E PROGRAMMER SEE TE
229. re desired SPI UART etc W hat voltage must the processor run at How fast must the processor run What type of IC package can use DIL surface mount These questions will help you determine the best choice of processor from the vast range available You will probably have a few favourite processor types in mind and so naturally the first task is to see if you can match any of them to the requirements you have writ ten down Assuming you don t find any thing suitable that would be rather easy wouldn t it it s time to start investigating the other processor variants and given the huge number of them this can be a daunt ing task Fortunately for us Microchip provide an on line tabular view of their products to help simplify this process It s available on their web site at www microchip com Under the Products column click on 8 bit PIC Microcontrollers for example and then click on PICI6 MCU under Product Family A large wide table is displayed showing each processor in the PIC 16 range listed with the key product parameters such as code size I O pins etc You can click on the arrow buttons at the top of each column to re order the table by any param eter you want perfect for homing in on devices that support a particular feature Once you have found a possible candi date processor download the datasheet and 20 take a look at the processor features in more detail Now is t
230. re unlikely to emerge in the short term but right now there s plenty of interest in the sensor market Dr J an G ustav Werthen of J DS Uniphase expects to find applications for power over optical in fields such as aero Space Communications defence and med ical equipment Further applications lie deep in the oceans where power over optical fibre cables is a convenient way of transmitting power to devices such as towed and static sensor arrays links to submersible vehicles surveillance devices dunking sonars and deep sea divers And finally You might not believe it but each year the British flush away mobile phone handsets worth 342 million A staggering 855 000 handsets are flushed away every year that s roughly 342 million we re loo sing based on the average insurance cost of replacing a phone This alarming news comes courtesy of the independent and free price comparison and Switching service SimplySwitch com Everyday Practical Electronics August 2007 Zinc Chloride Alkaline NiMH NiCD amp Sealed Lead Acid batteries We carry battery packs for racing amp radio control We also manufacture the NiCD Bot Pack a high performance custom made pack with forced cooling options for the most demanding applications Sample pricing GP AA Greencell 0 79 pk4 GP AA Greencell 0 13 cell in trade boxes of 320 ideal for schools eGP AA Ultra Alkaline 1 20 pk4 eGP AA NiMH 1300mAh 3 95 pk4
231. res of the dsPIC DSC is beyond the scope of this article and could easily fill several books so instead we will briefly introduce some of its key ele ments and then focus on how we can set up the dsPIC 30F 4011 for our motor control task The dsPIC IS termed as a Digital Signal Controller or DSC A DSC is asin gle chip embedded controller that inte grates the control attributes of a micro controller with the L grna i 1 1 L LI LI 1 LI LI LI LI T LI i i LI i LI LI LI LI LI LI LI LI LI LI LI 1 LI LI L LI LI LI m MICU OS E PaF y Daia Pati ATE FN Data Path LI A a on n a a 2e an a n Si an oo aa 2 aa a e a da kn dni a a a i which are pin and peripheral compatible with the dsPIC devices but have the DSP element removed One area where pure DSPs are often lacking is in the capability and mix of their peripherals The dsPIC DSC has reached a good middle ground with an extensive set of peripheral modules including timers UARTs SPI C ADCs DMA and advanced modules for audio and motor control Shown in Fig 2 is a simplified dia gram showing the architecture of the dsPIC DSP family The 16 bit dsPIC30F 4011 selected for our application is part of a motor control subset of devices and features a Motor Control PWM MCPWM module designed for high performance applica tions Along with this comes a dedicated Quadrature Encoder interface to monitor motor position
232. ro microcontrollers with A D converters O Fully protected expansion bus for project work USB programmable Q Can be powered by USB no power supply required ECIAL oFFEF ASSEMBLY FOR PICmicro Formerly PiCtutor Assembly for PICmicro microcontrollers V3 0 previously known as PlCtutor by John Becker contains a complete course in programming the PIC16F84 PICmicro 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 PICmicro 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 PICmicro MCU as each instruction is executed which enhances understanding Comprehensive instruction through 45 tutorial sections Includes Vlab a Virtual PICmicro microcontroller a fully functioning simulator Tests exercises and projects covering a wide range of PlCmicro MCU applications 8 Includes MPLAB assembler Visual representation of a PICmicro 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 E m r l o E
233. robably something elsewhere firewall security software Norton M cAfee etc blocking the launching of J ava applets Also more info na help at www j avat ester org index htm Hope that helps Alan Winstanley EPE Online Editor Vintage calculators web site There has recently been discussion on our Chatzone via www epemag co uk about ancient calculators Alan Winstanley emailed me with his comments came across this vintage calculators website and added a couple of my own oldies Casio M G 880 and Biolator 1100 www vintagecalculators com In 1980 annoyed all my workmates to death with my Casio MG 880 s monoto nous rendition of When the Saints EPE reader Nigel had also emailed Alan saying that he had found a vintage calculators site saying that he d added a new section Early Hand held LCD salu Library to the Vintage Calculators site and had added some photos Alan had sent to him see www vintagecalculators com html Icd_calculator_photo_library html He also commented that the Casio BQ 1100 hailed from the late 1970 s very early 1980 s described as a Biolator amp Watch The calculator had a built in calendar timer and stopwatch with a simple piezo sounder Powered by 2 x SG10 type cells a PVC wallet was pro vided that had a window enabling the time to be shown It measured 113 x 62 x 6mm It had a so called biorythm calculator that would calculate your PSI Physical Sentimental and Inte
234. rogrammer Es ji The system supports 64 pin and 100 pin AVR microcon trollers it is delivered with ATMEGA128 working at 10MHZ Many already made examples guarantee successful use of the system BIGAVR is easy to use Atmel AVR development system BIGAVR has many features that makes your devel opment easy You can choose between USB or External Power supply BIGAVR also supports Character LCD as well as Graphic LCD EasyPSoC3 Development Board with on board USB 2 0 programmer m zz The system sup ports 8 20 28 and 48 pin microcon trollers it comes with CY8C27843 Each jumper element and pin is clearly marked on the board EasyPSoC3 is an easy to use PSoC development system On board USB 2 0 programmer provides fast and easy in system programming Please visit our web page for more info http www mikroe com SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD PCB Production Development 0 1 Copper Stripboard Size Tracks Holes 25 x 64mm vay MP2s ia 64 x 95mm 24T 37H 95 x 127mm 36 50H 95 x 432mm 36T 170H 100 x 100mm SA y Sicha 100 x 500mm EKA a 119 x 455mm 46T 1799H Stripboard track cutter Solderless Breadboard Tie Points amp Size Power Rails 390 8l x60mm 2 RYS 175 x67 mm2 4 86 MiZ5x55mm 17 gt 4 08 175x42mm0 3 08 FM Many other sizes available Till also jump wires amp matrix board
235. rs it comes with a PIC16F877A pay ME A ZE 1 3 ai Ka Bi SON AN min l ME mikrolCD is a highly effective tool for the Real Time debugging on a hardware level The ICD debugger enables you to execute a mikroC mikroPascal mikroBasic program on the host PIC microcon troller and view variable values Special Function Registers SFR memory and EEPROM while the program is running On board USB 2 0 PICFlash programmer an ultra fast USB 2 0 programmer for MCU programming Continuing its tradition as the fastest PIC programmer on the market a new PICFlash with mikrolCD now supports more PIC MCUs giving developer a wider choice of PIC MCU for further prototype development Package contains EasyPIC4 development system USB cable Serial cable User s manual MikrolCD manual CD with software drivers and examples in C BASIC and Pascal language Note LCD DS1820 temp sensor and GLCD are optional mikroElektronika Compilers Pascal Basic and C Compilers for various microcontrollers zaam o ee mikroBASIC Supporting an impressive range of microcontrollers an easy to use IDE hundreds of ready to use functions and many integrated tools makes MikroElektronika compilers one of the best choices on the market today Besides mikrolCD mikroElektro nika compilers offer a statistical module simulator bitmap generator for graphic dis plays 7 segment display conversion tool ASCII table HTML code export communicati
236. rt The unit will not detect numbers dialled using pulse dial ling Circuit is microcontroller based Supply 9 12V DC Order Code PSU445 Main PCB 55xX95mMmM Kit Order Code 3153KT 20 95 Assembled Order Code AS3153 29 95 EPE PIC Controlled LED Flasher This versatile PIC based LED or filament bulb A flasher can be j used to flash i S LEDs The user arranges the LEDs in any pattern they wish The kit comes with 8 super bright red LEDs and 8 green LEDs Based on the Versatile PIC Flasher EPE Magazine Dec 02 See website for full details Board Supply 9 12Vdc LED supply 9 45Vdc depending on number of LED used PCB 43x54mm Kit Order Code 3169KT 11 95 Most items are available in kit form KT suffix or assembled and ready for use AS prefix FM Bugs amp Transmitters Our extensive range goes from discreet surveillance bugs to powerful FM broadcast transmitters Here are a few examples All can be received on a standard FM radio and have adjustable transmitting frequency MMTX Micro Miniature 9V FM Room Bug s Our best selling bug Good performance Just 25x15mm Sold to detective agencies worldwide Small enough to hide just about anywhere Operates at the less busy top end of the commercial FM waveband and also up into the more private Air band Range 500m Supply PP3 battery Kit Order Code 3051KT 8 95 Assembled Order Code AS3051 14 95 HPTX H
237. s A Advertising Rates per insertion 2 insertions Full Page 265 x 177mm 450 Half Page 265 x 85 or 129 x 177mm 245 Third Page 265 x 55mm 165 Quarter Page 129 x 85mm 135 Sixth Page 129 x 55mm 95 0 MP a eto 95 90 Eighth Page 65 x 85mm 85 80 30 eee we gt gt Classified per single column cm min 2 5cm Aao 9S Covers 265 x 177mm Leaflet or booklet Inserts Larger Inserts Leaflet or booklet inserts per thousand PO A D O 1 85 75 9 N A Wimborne Publishing Lid T 01202 873872 F 01202 874562 Sequoia House 398A Ringwood Road Ferndown Dorsel BH22 9AU WWW epemas co uk WWW epemas com Advertising Manager Siewart Kearn E stewart Kearn wimborne co uk All of our rates are subject to VAT at the current rate and the publisher reserves the right to charge extra for excessive setting colour separations etc F 3 Using MPLAB How to use MPLAB when writing the source code for your PIC projects Part Three Debugging by Mike Hibbett left off last month with a simple Wie built and successfully run ning in the MPLAB simulator but with one small problem still hidden from view The purpose of the program if you haven t gathered it already from the com ments is to write a specific pattern of ones and zeros to the 8 bit PORTD If you had LEDs connected to that port three of them would have illuminated T hat s the intenti
238. s a single programming block It will often be essential to use macros in order to keep programs down to a reasonable size on the screen but they provide a neat and efficient aid to program ming This is not a matter of making a virtue of a TUTI PEF necessity and the ability to use macros is a powerful feature One step at a time There is a built in simulation facility and this will work in real time if the appropriate clock frequency is set The components such as displays and LEDs are included in the simulation and respond in the appropriate manner In the case of input devices such as switches the program provides the correct respons es to input from the user In the example of Fig 8 left clicking one switch results in the count on the display incrementing while left clicking the other switch decrements it There is also a facility for stepping through the program one instruction at a time This is mainly included as an aid when troubleshooting and it should work well in this guise Itis also useful for those learning about programming since it enables the user to see the exact effect of each instruction Once a program has been perfected there are three ways of using it One way is to com pile the program to assembly code which can then be used in the same way as any PIC assembly language program The second option is to compile the program to C The final option is to compile the program to PIC whi
239. s such as using macros Last and by no means least there are some useful video tutorials and other Support at the M atrix M ultimedia website which includes an active Forum with atansi Hapan ann Ras tan queries answered by the Matrix support team within 24 hours Conclusion The E Blocks and the M ulti programmer are well made and competitively priced They provide an easy means of experi menting with PIC circuits and programs and can certainly be recommended Experienced programmers will only require the PPP program in order to use the hardware effectively while the Flowcode software provides an easy starting point for beginners It also offers experienced PIC programmers an alternative and potentially quicker approach to PIC programming Version 3 of Flowcode has no radical changes from the previous version but there are a number of useful enhance ments such as string handling 16 bit arithmetic and support for 18xxxx series PIC devices The simulation and single step facilities make troubleshoot ing relatively painless and it is also pos sible to learn a great deal about PIC pro gramming by experimenting with these facilities The Flowcode program has a conven tional Windows user interface where things generally operate as one would expect This makes it easy for experienced PC users to learn and use Again it is a product that is certainly well worthy of recommendation EPE The ee Waren Wah ane ot Ii
240. s to suit see text 1 miniature PC mount piezo buzzer WD1 Semiconductors 1 Atmel AT90S2313 4 or 10 microcontroller programmed with RFID HEX IC1 Prepro grammed chips are available from Magenta Electronics 1 ID Innovations ID 12 RFID module IC2 1 MC34064P 5 under voltage sensor IC3 1 4MHz crystal HC49 package X1 2 BC337 NPN transistors Q1 Q2 1 BD681 NPN Darlington transistor Q3 3 1N4004 diodes D1 D3 1 1N4745A 16V 1W Zener diode ZD1 1 3mm high intensity red LED LED1 Capacitors 2 100uF 16V PC electrolytic 2 100nF 50V monolithic ceramic 2 22pF 50V ceramic disc Resistors 0 25W 1 2 10kQ 1150Q 2 1kQ 1109 1W 5 1 220Q 5 Band Code 1 brown black black red brown brown black black brown brown red red black black brown brown green black black brown brown black black gold brown 25 pan OO ET LADAN 3 This view of the copper side of the PC board shows how REG1 and D3 are installed holes Make sure that it s sitting square on the PC board before soldering it in place The ID 12 s pins are spaced on 2mm centres which means that there s very little space between the pads After soldering use your multimeter to do a continuity test between adjacent pins to eliminate the possibility of fine solder bridges The remaining components can now be installed with attention to the fol lowing points 1 When fitting the IC socket be sure to align the notched
241. s 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 Soeech 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 16 99 224 pages 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 electronics and computing They are supplied by mail order to your door Full ordering details are given on the last book For 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 hig
242. sed all measurements can be printed copied to the clipboard and saved as text bitmap or vector graphics for subsequent analysis or to import into other programs PoScope is ideal for use by electronics hobbyists students and engineers alike and is particularly suited to those developing with microcontrollers such as PIC and AVR analyser art recorder logic a decoding pattern generator and pieces of test equipment for 99 in uding UK q ii ae YOU Alyser A PoScope provides the ollowing 2 channel cre operation modes e 2 channel oscilloscope with 100Hz to 200kHz sampling 20V to 2OV input range 10 bit ADC resolution absolute differential and external triggering adjustable pre trigger and marker measurements e 2 channel spectrum analyser with klirr factor measurement Hamming Hanning Blackman and Blackman Harris FFT window functions SQ and VAT ecorder with 0 01Hz to 200k sampling maximum minimum and average voltage measurements for each channel and waveform record over several tens of hours 16 channel 8 when pattern generator used logic analyser with 1kHz to 8MHz sampling versatile triggering with adjustable pre trigger external clocking preset pulse miss preset bit sequence edge decoding of UART SPI 12C and 1 wire serial interfaces get the features of an ae spectrum A UART SPI FC and i esi bus Uare War a generator a equivalent to six e 8 ch
243. sented by complex num bers Complex numbers are so called because of their two dimensional qualities not because they make the maths harder although some people might try to dispute this We will not go into the details of com plex number theory here but simply accept that s is a special number that somehow holds both phase and frequency information This will be sufficient to introduce two key concepts poles and zeros which occur in discussions of cir cuit frequency response stability and compensation Using Xc 1 SC we can rewrite the for mula for V out from above Remember that V in and V out are NOW complex numbers as well as s Vins an Vs R 1 sC Everyday Practical Electronics August 2007 If we multiply both the top and bottom of the formula by sC we get l Vi Vis RCs 1 This is a neat form but we really need to gets on its own so we multiply top and bot tom by 1 R C to get y VR C yr 0 0001 Jr s l RC s 0 0001 This formula has one special value for s which is when s 1 R C 0 0001 At this point we are dividing by zero so the formula value goes to infinity The value of s for which this occurs is called a pole of the circuit s response The term pole reflects that fact the formula value shoots up to very large values around this point and infinity at the pole itself In general a circuit s response may have multiple poles For example if the circuit response was we woul
244. ses Re locatable code This wraps up our coverage of the sim ple single source file code development within MPLAB It is possible to develop complex programs this way and you can even fake modular software development by adding in several source files using the include directive just as we did to include the processor header file Nothing wrong with this all of the author s PIC assembly projects are developed this way But that may change when we see how re locatable software development can make big proj ects easier to write and enable you to re use software already developed in new projects So what does re locatable mean and how does it differ from the way we have been writing software so far When developing with a single non re locatable source file the assembler program knows exactly what memory location each instruction will go into because you tell it You specify at the beginning of your file the location where instructions will start with an ORG state ment so instructions like loop goto loop can be resolved into the correct instruction word because the assembler knows exactly where the label loop resides In our simple example program we didn t specify an ORG statement When we do that the assembler assumes the program starts at location 0 It can then immediately con vert the instructions into a hex file That s all well and good but as projects get more complex we want to be abl
245. shown in Fig 4 It is the same as used in many EPE construc tional projects published over the last few years It was originally designed and described by Joe Farr in his Serial Interface design of October 03 to which readers are referred to for more information INVERTING VARIABLE GAIN AMPLIFIER Fig 3 Two modes of control using the DS1267 digital potentiometer chip Everyday Practical Electronics August 2007 apacitors 1kQ R1 NN O J GBOCOMOOJRO aeaaea Ne 10Q R11 Power supply The unit has been designed to run from a 9V DC power source preferably regulated although a battery supply can be used Current consumption is about 80mA Three voltage levels are required derived as shown in Fig 5 The 9V DCis input via diode D4 which prevents the wrong voltage polarity being VARIABLE BIAS ADJUSTMENT ICL7660 voltage converter IC 14 Maxim MAX232 dual serial interface IC16 20MHz crystal X1 10pF ceramic disc 0 2in pitch C1 C2 C7 C9 100nF ceramic disc 0 2in pitch C4 C11 to C13 C16 1uF radial elect 25V C17 to C21 4uF radial elect 16V C3 C5 C8 22uF radial elect 10V C6 C14 C16 2200uF radial elect 16V C10 esistors 0 25W 5 carbon 10kQ R2 R3 R8 to R10 11kQ or 10kQ see text R5 R7 100k R4 R6 connected Minor smoothing is provide by capacitors C10 and C11 Regulator IC12 drops the supply to 5V for use by the digital control chips in the ci
246. signal track which passes underneath them That done fit the electrolytic capaci tors again taking care to ensure that they go in with the correct polarity The only exceptions here are the 1uF and 4 7uF electrolytic capacitors which are non polarised It s now simply a matter of com pleting the board assembly by fitting the large hardware items These parts include the DC power socket the three dual RCA phono connectors and the control pots Before fitting the four control pots you will probably need to shorten their spindles so that the knobs sit close to the front panel when the amplifier is finally assembled This job can be done using a small hacksaw cut each spindle at a point 9mm from the threaded bush and remove any burrs with a small file Each pot mounts directly on the PC board Be sure to fit each dual pot VR1 VR2 and VR3 in its correct position as they all have different values Each pot should be pushed down onto the board as far as it will go before solder ing its pins Once all four pots have been mount ed on the board cut a 160mm length of 0 7mm tinned copper wire and pass one end down through the small hole in the left front corner of the board just to the left of VR4 Solder it to the Everyday Practical Electronics August 2007 AUDIO PRECISION SCTHD W THD N vs measured LEVEL W AUDIO PRECISION SCTHD W THD N vs measured LEVEL W 10 10 SS ee EN os Ap
247. so advisable When used with an engine im mobiliser in a car the module can be powered either permanently or only when the ignition is switched on The latter method eliminates battery drain as well as the need to arm the module each time you exit the vehi cle However it does mean having to swipe your tag after inserting the keys in the ignition Whichever method you choose the positive power lead must be wired via the fuse box The negative lead simply connects to chassis ground How secure is it Each tag is factory encoded with a unique 40 bit number This means 240 possible combinations a very big number indeed It s therefore extreme ly unlikely that someone will have a tag with the same code as yours It s also impossible to use a scanning device to crack the code because the module generates an alarm as soon as This photo shows a sample collection of tags including the key fob and credit card styles mentioned in the article Reproduced by arrangement with SILICON CHIP magazine 2007 www siliconchip com au three consecutive unknown IDs are detected Not only that but the very low tag to reader transmission speed means that it would probably take years to run through all of the possible combinations As with lock and key security it might be possible to borrow a tag and copy it This could be achieved by reading the ID and programming it into a read write tag effectively duplic
248. stem and ActiveSync to connect to a PC Text is entered by stylus and software keyboard dis play The TouchFLO screen distinguishes finger sweeps from stylus prods The Touch launched in Europe and A sia in June and in the US later this year The cost without network subscription subsidies is 449 euros Says John Wang Chief Marketing Officer Simplicity is a word that s overused even over abused Until now phones have been push button centric This is touch centric From today things will be different Barry Fox TECFNG TALK mark nason Two Birds With One Stone Adapting a pipeline previously designed for one purpose alone to carry two payloads at once makes sound economic sense It also involves some pretty smart science as Mark Nelson reveals not once but twice AY BE you never thought about it MI there s something remarkably elegant about the telephone system As well as carrying voice and data signals those copper wires that we take for granted also deliver power An always on supply of 50V powers your telephone and trickle charges NiCad batteries in other devices while the wires also deliver 75V AC at 25HZ whenever the phone rings warbles or what ever it does to disturb your calm This multi tasking technology is hardly new dating back more than a hundred years Some more recent communication systems are not so multifunctional however The eth ernet data distribution cabling in offices is a sign
249. sues per year PN See cree meee tes eee eee eres eee eet Everyday Practical Electronics periodicals pending ISSN 0262 3617 is published twelve times a year by Wimborne Publishing Ltd USA agent USACAN at 1320 Route 9 Champlain NY 12919 Subscription price in US Address Me ETE EEEE TEE ETE T E 60 US per annum Periodicals postage paid at Champlain NY and at additional mailing offices POSTMASTER Send USA and Canada address changes to Everyday Practical Electronics c o Express Mag PO Box Postcode moree ery on erate E E Et cae JE n e meet ance meen weenie 1 2769 Plattsburgh NY USA 12901 0239 Everyday Practical Electronics August 2007 37 Regular Clinic lan Bell Surgery Linear Voltage Regulators and Capacitors Part Two L month we started looking at a ques tion posed by Techno on the EPE Chat Zone access via www epemag co uk who was asking about the capacitors which are required on the output of some regulator ICs Techno pointed out that the values were too small to be useful for smoothing so what were they for The answer is they are added to the circuit to ensure that the regulator is stable does not oscillate a process known as compensation It is worth noting that large smoothing Capacitors where used are connected to the output of the rectifier in supplies using a transformer connected to the AC mains However regulators are also used in other situations including battery powered equi
250. suring just 50 x 70mm In fact it s small enough to be concealed behind a standard electrical wall plate or similar It can be operated as a stand alone keyless entry system or as part of a larger alarm system Three open collector outputs and a single digital input are accessible via a 4 way terminal block One of the outputs is designed to drive a 12V DC solenoid actuated door strike bolt These are available from most security equipment retailers The two remaining outputs can be hooked into an existing alarm system to supplement or replace an existing point of entry keypad or other remote control device The digital input can be wired to a tamper switch to detect removal of the cover or the unit from the wall To cater for varying installations the module can be programmed to operate in one of four modes as follows Mode 1 no alarm features keyless entry only door strike energised on tag validation Mode 2 alarm operation door strike energised on disarming Mode 3 alarm operation door strike energised on arming Mode 4 alarm operation door strike energised on arming and disarming In most cases the RFID module will be mounted outside the protected perimeter so you ll want the strike to be energised on disarming Mode 2 The desired operating mode is selected by performing a simple initialisation procedure as we ll see a little later Everyday Practical Electronics August 2007
251. t and circuit testing techniques the reader should be able to confidently tackle servicing of most electronic projects Order code BP239 5 49 STARTING ELECTRONICS THIRD EDITION KEITH BRINDLEY A punchy practical introduction to self build electronics The ideal starting point for home experimenters techni cians and students who want to develop the real hands on skills of electronics construction A highly practical introduction for hobbyists students and technicians Keith Brindley introduces readers to the functions of the main component types their uses and the basic principles of building and designing electronic cir cuits Breadboard layouts make this very much a ready to run book for the experimenter and the use of multimeter but 96 pages not oscilloscopes and readily available inexpensive com ponents makes the practical work achievable in a home or school setting as well as a fully equiped lab Order code NE42 11 50 THE AMATEUR SCIENTIST CD ROM CD ROM VERSION 2 The complete collection of The Amateur Scientist articles from Scientific American magazine Over 1 000 classic science projects from a renowned source of winning projects All projects are rated for cost difficulty and possible hazards Plus over 1 000 pages of helpful science tech niques that never appeared in Scientific American Exciting science projects in Astronomy Earth Science Biology Physics Chemistry Weather and m
252. t can be difficult to work out where a problem exists So the best approach is to start with a very simple pro gram just turn a few I O lines high and low then enter a continuous loop This will give you some confidence that the IDE settings and the hardware itself are working properly You can then build upon this code routine by routine Let s say you write your code in one go and then try to run it on your hardware If it doesn t work then you have no idea where to start to find the problem the fault could be in hardware software or both Take things a step at a time small steps at first then progress to larger ones as your confidence In the system grows Bootloaders If you take this approach once you have a few small projects under your belt then the process will quickly become second nature and will speed up your projects rather than appear an awkward overhead There is however a way to simplify things from the start use a pre existing boot loader like the one we described in an ear lier Pic n Mix article B ootloaders give you a body of code that is already known to work with suitable configuration bit settings Our bootloader even provides a set of skeleton applica tion files that can save you thinking about where to put your code The maximum benefit and time saving comes when you choose a processor that matches or is very similar to the one used by the bootloader software It s not always an opti
253. t outputs and one input to monitor eight switches Although crude systems of this type are cheap to implement and require no power supply Everyday Practical Electronics August 2007 Ins and Outs Occasionally queries are received about using output ports as inputs which is something that can after a fashion be achieved A few websites have described dubious ways of doing this which usual ly entail forcing outputs to the desired logic level and then reading from the output port Apparently this will work in some cases but using an output to force anoth er output to the required level is clearly inviting problems Ultimately it is likely to result in damage to at least one of the output devices In most cases the port does not have the wherewithal to read an the output lines so it will not work at all The proper method of using outputs as inputs is to use the outputs in conjunction with one or more true inputs lines togeth er with a simple scanning process It is a system that is often used for reading key boards or any similar application where there are numerous switches to monitor Fig 1 shows the way in which a basic sys tem of this type can be implemented using the printer port of a PC Each of the data outputs DO to D7 is connected to the port s Error input which is at bit 3 of the Status Register In each case the connection is by way of a resistor R1 to R8 and a diode D1 to D8 network Swit
254. t to be assigned to consecutive values For example CBLOCK 0x23 size width length ENDC Assigns the value 0x23 to size 0x24 to width and 0x25 to length There are more complex ways of using CBLOCK which you can explore in the help system of MPLAB They are not essential for nor mal programming tasks Oscillators To wind up the debugging of this exam ple program you may be wondering about the source of the oscillator signal We never mentioned clock speeds and if you look at the picture of the demo board there is adistinct absence of the usual crystal So what s going on Going to the Configure Configuration Bits menu option in M PLAB reveals the answer by default the oscillator source is EXTRC an external resistor and capacitor source and a further investigation of the PCB reveals the com ponents The MPLAB simulator doesn t care what clock source you choose because it runs along at its own slow rate controlled by the PC The hardware debugger however will faithfully use whichever clock source you choose which must be physically Everyday Practical Electronics August 2007 located on the target hardware The demo board is equipped with the resistor and capacitor oscillator circuitry so the default configuration bit settings are fine Don t forget to set your Config bits appropriately to match whatever oscillator circuitry your design uses or you could be in for some Surpri
255. tability headroom we have for gain mar gin and phase margin which we defined last month 38 It is useful to draw the frequency response of the circuit this is a graph of how gain and phase shift vary with fre quency from which we can readily mea sure gain and phase margin or see if the system will be unstable It is obvious from last month s article and the preceding summary that the vari ation of a circuit s gain and phase with frequency are critical to consideration of Stability and compensation Unfortunately analysis of circuits fre quency responses really requires some advanced maths although we can treat some aspects more simply We will continue by looking at the fre quency response of a couple of simple but important circuits in order to intro duce some of the maths and terminology associated with compensation circuits We will then look at compensation for op amps and return next month to finally consider stability and compensation for regulators Fig 1 RC circuit with one pole First Analysis The circuit in Fig 1 is a potential divider so we can find the output voltage from the input voltage by dividing the input voltage by the total impedance and multiplying by the impedance strictly speaking reac tance of the capacitance Xc across which the output occurs The total imped ance of the resistor and capacitor is given by RFX Note that we cannot simply add the R and X values because
256. the required precision IC2isa 5V 100mA fixed positive voltage regulator and is crucial to the stability of the circuit Its input would typically be fed by a mains to DC plugpack power supply Antenna construction The antenna is constructed of seven lengths of approximately 1mm diameter enamelled copper wire soldered together as one at the base see Fig 2 The tips are sharpened with a fine file to improve sensitivity These seven copper javelins are each 76mm 3in long from the point at which they separate from their base and form a 76mm 3in diameter circle at their tips At their base the copper javelins are soldered to the core of a 15m 15yds approx length of screened microphone cable This must have a quality screen which cheap substi tutes sometimes do not have The cable s core at the antenna end together with its insulation protrudes from the screen by 102mm 4in as shown in Fig 2 That is 102mm 4in of the outer screen and insula tion is cut away The copper javelins are fixed into the top of alength of PVC piping The microphone cable is then secured with a cable tie to ensure that it will not pull loose The whole assembly is mounted about 2m 6ft off the ground at its tips and preferably half a metre 18in or more away from any exterior wall It is of no consequence whether it is located in an open or a leafy area so long as it does not come into direct contact with flor
257. 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 14 99 298 pages ANDROIDS ROBOTS AND ANIMATRONS Second Edition John lovine Build your own working robot or android using both off the shelf and workshop constructed materials and devices Computer control gives these robots and android
258. this refit the stop washer with its cranked locating pin passing down into the second hole from the anticlockwise end of the series moulded into the switch body the hole between the moulded 3 and 4 Fig 5 THD noise vs output power into 8Q loads Once again the right channel is worse due to power supply noise but it s still generally substantially less than 0 1 Finally refit the star lockwasher and nut threading the nut down against the star lockwasher just hard enough to fasten everything in place If you now try turning the switch spindle by hand you should find that it has only three positions The switch can now be fitted to the PC board It must be orientated so that the round spigot moulded into the top front of its body is directly behind the spindle as indicated in the wiring diagram Fig 6 The pins on the rear of the switch can then be pushed down through the corresponding holes in the board until the moulded black lugs that hold the switch body together are resting The rear panel carries three pairs of RCA phono input sockets Tuner MP3 and CD the heatsink and the left and right channel speaker terminals There s also an access hole for the power socket far right Everyday Practical Electronics August 2007 53 e 220nF 100nF gt _100nF xc x mm LEFT HANNEL Ci NP x NP CS 8 NP 1N5404 1N5404 on the board Finally the pins can all b
259. tive to assign vari ables CBLOCK can only be used in non re locatable development where you speci fy absolute addresses for variables in re locatable development you use the RES directive as you saw in the example above The RES directive means reserve some space in the current memory area You use it like this label RES number label is the name that you want to assign to the first location in this reserved area and number is the number of bytes you want to reserve Normally you use one RES statement for each byte variable that you use for example index RES 1 count RES 1 total RES 1 You can however reserve more than one byte for example for an input buffer buff RES 16 Everyday Practical Electronics August 2007 The label buff points to the first byte in this 16 byte buffer to get to the others use the normal techniques Either refer to them using absolute addresses movfw buff 1 or use the INDF register to index into it more complicated but the better solution when accessing large buffers Benefits That s all you need to get started with re locatable assembly At first it may appear to provide no additional benefits but with time and a few projects under your belt you will start recognising useful functions place them in their own independent source files and begin reaping the benefits of code reuse As time goes by you may want to place all these functions into one or more library f
260. to give a pole at a sufficiently low frequency H ere anoth er aspect of negative feedback comes to the rescue A useful piece of circuit theory called the M iller Theorem shows us that a capac itor placed between the input and output of an inverting amplifier i e a negative feed back capacitor has the same effect on the circuit s response as a Capacitor approxi mately A times larger placed between the input and ground see Fig 8 Using the Miller effect we can achieve the same effect on the frequency response of the circuit as in Fig 7 by adding a nega tive feedback capacitor on the second amplifier stage but using a capacitor A times smaller This enables us to use a capacitance value which is reasonable for fabrication on an op amp IC and achieve a sufficiently low frequency pole to implement dominant pole compensation Fig 9 shows a block diagram of the internal circuitry of an op amp showing the compensation capacitor added to the gain stage between the differ ential input stage and the output stage Next month we will see how we can use an added zero in the compensation of regulator circuits Get your magazine instantly anywhere in the world buy and download from the web TAKE A LOOK A FREE ISSUE IS AVAILABLE A one year subscription 12 issues costs just 15 99 US Back issues are also available 40 Everyday Practical Electronics August 2007 w Our online store contains an ever exp
261. to simulate on your PC In addition to the Teach In series the book includes 15 CMOS based simple projects from the Back To Basics series by Bart Trepak these are Fridge Freezer Alarm Water Level Detector Burglar Alarm Scarecrow Digital Lock Doorchime Electronic Dice Kitchen Timer Room Thermometer Daily Reminder Whistle Switch Parking Radar Telephone Switch Noughts and Crosses Enigma and a Weather Vane There is also a MW LW Radio pro ject in the Teach In series 152 pages CD ROM 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 instructions provided including numerous step by step photographs 288 pages large format WOLE C1 14 99 Order code ETI 8 50 MORE ADVANCED ROBOTICS WITH LEGO MINDSTORMS Robert Penfold Covers
262. tor will double that capacity to an amazing 20 amps e Kit includes PCB plus all electronic components to build the 10A version G ladder of noisy sparks that emits the distinct VOLTAGE smell of ozone This improved circuit is suited to modern high power ignition coils and will deliver a spectacular visual display Kit includes PCB pre cut wire ladder and all electronic components e 12V car battery or gt 5 amp DC power supply required www jaycarelectronics co e a ur FREE catalogue 0800 ae 7241 3V 9V DC to DC Converter Kit KC 5391 4 95 post amp packing This little converter allows you to use regular Ni Cd or Ni MH 1 2V cells or alkaline 1 5V cells for 9V applications Using low cost high capacity rechargeable cells this kit will pay for itself in no time You can use any 1 2 1 5V cells you desire Imagine the extra capacity you would have using two 9000mAh D cells in replacement of a low capacity 9V cell Kit supplied with PCB and all electronic Component Automotive Courtesy Light Delay KC 5392 5 95 post amp packing This kit provides a time delay in your vehicle s interior light for you to buckle up your seat belt and get organised before the light dims and fades out It has a soft fade out after a set time has elapsed and has universal wiring Kit supplied with PCB with overlay all electronic components and clear English instructions e Ac publis J in Everv P Recommended box UB5
263. ts to the oscilloscope hard ware via a USB cable so that no other power source is required The USB interface emulates a serial port so that the oscilloscope may be accessed as a Serial port device For more information contact Audon Elect ronics tel 44 0 115 925 8412 fax 44 0 115 925 9757 email info audon co uk web www audon co uk Everyday Practical Electronics August 2007 The handset runs off the mains supply If there is a break in power the handset will run off its 9V back up battery for up to six weeks The Wi Safe Wireless Home Safety System will be available through B amp Q and other retailers later in the year The handset will retail for under 30 and the smoke and CO alarms will range in price from 15 to 35 Touch Control Taiwanese company HTC thinks it can change the way we use handheld devices with a new kind of touch screen control HTC has spent the last ten years growing from 10 peo ple to 5000 through working with M icrosoft and networks such as Orange and T M obile making their smartphone PDAs A year ago HTC started selling phones under its own name and is now challenging Apple with a direct competitor to the upcoming iPhone The HTC Touch has no keypad It works by touch alone Sweeping a finger over the TouchFLO screen changes interface menus and scrolls through them from weather to music camera pictures and contact lists The Touch phone uses Windows Mobile 6 operating sy
264. tween the earth and the atmosphere itis therefore possible to predict with a high degree of confidence when a risk of light ning is present More often than not an atmospheric charge monitor will use awkward methods of detecting charge a radioactive blade for instance or complex high impedance cir cuits The Atmospheric Charge M onitor shown in Fig 1 is surely one of the simplest self contained circuits of its kind Its secret lies above all in impedance matching that is matching the current of atmospheric trickle to the input impedance of an IC Circuit theory Comparator IC1 compares the potential at the antenna non inverting input pin 3 70 ANTENNA Fig 1 Circuit diagram for the Atmospheric Charge Monitor Preset VR1 should be a multiturn ceramic type with the potential at the earth inverting input pin 2 Pins 2 and 3 of ICI have very slight internal biasing which proves to be almost perfect for the application here Also IC1 s open loop gain is almost per fectly matched to fluctuations in atmos pheric charge so that the needle of moving coil meter ME1 will travel more or less across its entire range depending on the charge Not least the output IC 1 pin 6 to OV is current limited to about 1mA which nicely matches M E1 Preset potentiometer V R 1 must be a multi turn type It is an offset adjust control and serves to balance the circuit Note that sin gle turn potentiometers do not have
265. u will see an error message from the linker like this Error section udata can not fit the section Section udata length 0x0000010f W hen this happens you should split your variables into two or more regions by giv ing two or more UDATA statements with different names areal UDATA varl RES OxF0 area2 UDATA var2 RES OxF0 Everyday Practical Electronics August 2007 Bank select bits One of the consequences of using the link er to place your variables where it wants is that you do not know what memory bank they are in so you do not know how to set the bank select bits when you need to access them There are two solutions to this The first if you are using a PIC18F processor is to place all your variables in the UDATA ACS section That way your vari ables will always be accessible no matter what the bank select bits are In PIC12 16 parts you can use the shared memory region UDATA_SHR Although this is quite small The second more general solution and necessary when you have a lot of variables is to use the assembler directive banksel When you specify this the linker will set the bank selection bits to the bank of what ever variable you specify The banksel directive expands to bsf instructions so the content of the W register is unaffected Y ou use It directly in your code like this banksel varl movwf varl banksel var2 addwf var2 w You may have noticed that we didn t use the CBLOCK direc
266. ual laboratories worked examples and pre designed circuits allow students to learn experiment and 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 ANALOGUE ELECTRONICS Complimentary output stage DIGITAL ELECTRONICS V2 0 Filter synthesis 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
267. uch more The most complete resource ever assembled for hobby ists and professionals looking for novel solutions to research problems Includes extensive Science Software Library with even more science tools Suitable for Mac Windows Linux or UNIX 32MB RAM minimum Netscape 4 0 or higher or Internet Explorer 4 0 or higher Over 1 000 projects Order code AS1 CD ROM 19 95 CD ROM eBAY FOR BEGINNERS Cherry Nixon There are two kinds of people those who are trading on eBay and the rest who are missing out Though eBay has been embraced by entrepreneurs all over the world it remains the peoples site and offers the largest market for the smallest fee eBay presents an opportunity for everyone the trick is to master it This book shows you how to start trading on eBay UK It also offers advice on getting organised and tips to put you ahead The book has been developed from Cherry s popular hands on course Buying and Selling on eBay for Technological Simpletons In addition to fully explaining eBay and how to trade on it there are sections on Paypal producing pictures of your sale items fees and accounts safety and security including what to do when things go wrong and what protection is provided Order code BP551 8 99 288 pages 178 pages Music Audio and Video MAKING MUSIC WITH YOUR COMPUTER Stephen Bennett Nearly everyone with musical aspirations also has a com puter This same computer can dou
268. uct range with a system that could help save hundreds of lives The Wi Safe range of home safety products has been designed to provide the ultimate in early warning of the danger of fire or carbon monoxide in the home Central to the system is the Remote Warning Handset a small portable handheld device that works in con junction with FireAngel s Wi Safe Smoke Alarm and Wi Safe Carbon M onoxideA larm providing audible and strong visual alerts The warning handset can be placed any where in the house typically by a bed to ensure that the user wakes when potential fire smoke and carbon monoxide problems are detected elsewhere in the house The impor tance of this is paramount A study in Australia has shown that only 6 of children aged 6 to 15 wake up when a standard smoke alarm installed in a landing is triggered All Wi Safe alarms and accessories incor porate FireA ngel s wire free communication technology with unique code encryption enabling signals from remote alarms to acti vate the handset Simple to use the Remote Warning Handset can be placed in any location It responds to either the Wi Safe Smoke Alarm or Wi Safe Carbon Monoxide Alarm from around the house and activates the handset to immediately sound and flash to warn of either the danger of fire or the presence of carbon monoxide which then gives residents an early alert and a better chance of escaping An indicator will illuminate on the handset to ident
269. unit is shown in Fig 1 The PIC is a PIC16F877 20 device IC1 running at 20MHz set by crystal 12 X1 The PIC s mode of control is set by the PC which it is believed can be running under Windows platforms W95 W98 ME and XP providing that the PC has a serial communications port this design cannot be used under USB control The PC control will be described later When the PC has selected analogue waveform display up to two chan nels can be displayed their signals initially processed by the circuit to be described shortly Fig 2 and input to the 8 channel multiplexed ADC IC3 of which only two channels are used IN1 and IN2 Under control of the PIC the ADC repeatedly samples the analogue input from the selected channel converting it to an equivalent digital value storing the value in the 32 kilobyte memory chip IC2 of which only 8K is used Data is sent by IC1 PORTD with the address data lines controlled jointly by PORTA and PORTB Address lines A1 and A3 are held permanently low The memory s Output Enable OE is controlled by IC1 RCO pin 15 and the Write Enable WE control led via the passive diode NOR gate comprising diodes D2 and D3 plus resistor R3 This line is controlled by IC1 RC1 pin 16 in conjunction with RC4 pin 23 The reason for dual control is com plicated as will be explained by ex amination of the PIC s source code But itis determined by the need for data to be stored
270. unning in this IC is responsible for receiving the data and deciding what action to take Under program control the incom ing data is reassembled back into byte sized chunks and a check is made to see if the ID code matches any of the codes stored in the on board You can easily make 2 way and 4 way pin headers for JP1 and JP2 3 by cutting down a longer strip Everyday Practical Electronics August 2007 memory EEPROM What happens next depends on the selected operat ing mode Three output bits PD4 PD6 drive the base circuits of switching transis tors Q1 Q3 If an ID match is found the microcontroller can switch Q1 on or off to arm or disarm a main alarm system In addition it can switch Q3 on for a short period to energise a so lenoid activated door strike Alternatively if the ID code is not recognised then an alarm might be triggered by switching Q2 on The ex act sequence depends on the operating mode and the current alarm state as described previously Diodes D2 and D3 are included to protect transistors Q2 and Q3 from the back EMF spike induced by relay and door strike solenoids The two remaining outputs PB1 and PB7 used in this design drive LED1 and a piezo buzzer WD1 to provide user feedback On the input side tamper detec tion is provided by sensing a level change on the PD3 input bit During power up the microcontroller reads this input and stores its state This method allows either nor
271. ust 15 99US approx 9 00 per year available from www epemag com ioe pan armasar i m W a A La WA l me ee ae L ae Wi Everyday Practical Electronics August 2007 SUBSCRIPTIONS Subscriptions for delivery direct to any address in the UK 6 months 18 75 12 months 35 50 two years 66 Overseas 6 months 21 75 standard air service or 30 75 express airmail 12 months 41 50 standard air service or 59 50 express airmail 24 months 78 stan dard air service or 114 express airmail To subscribe from the USA or Canada call Express Mag toll free on 1877 363 1310 Online subscriptions for downloading the magazine via the Internet 15 99US approx 9 00 for one year 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 Sequoia House 398a Ringwood Road Ferndown Dorset BH22 9AU Tel 01202 873872 Fax 01202 874562 Email subs epemag wimborne co uk Also via the Web at MED ROU A Amon o Subscriptions start with the next available issue We accept MasterCard Amex Diners Club Maestro 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 PVC printed with the magazine logo in gold on the Spine Price 7 95 plus 3 50 p amp p for overseas readers the postage is 6 00 to
272. ut some previous experience with electronic circuits is assumed Covers the basic concept of a micro controller fundamentals of a PIC based circuit and using the MPLAB program Further chapters introduce binary PIC architecture the instruction set the PIC memory map and special registers plus real world programming Four simple projects are also fully described a Wavy Wand an Electronic Dice a Games Timer and a Pulse Monitor The associated CDROM contains the book in PDF format MPLAB plus instruction manuals in PDF format and all the programs covered in the book as assembler ASM files Those that wish to programme their own PICs will require a PIC programmer In addition a p c b based hardware kit is also available that makes up into the Wavy Wand which will spell out a short message via a line of l e d s when waved through the air stole 4 PLUS CDROM 190 pages A4 spiral bound Book CDROM Order code DOC1 99 00 1 E D EN EERO Ro 01017 99 50 BOOK ORDERING DETAILS All prices include UK postage For postage to Europe air and the rest of the world surface please add 2 per book For the rest of the world airmail add 3 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 Maestro to DIRECT BOOK SERVICE WIMBORNE PUBLISHING LTD S
273. vacsa CISY 8 10A Panel Meters High quality analogue panel meters class 2 zero point correction mirror scale and prewired for panel illumi nation Meter size 46 x 60mm Cutout size 38mm All meters 5 89 each 6V Lamps 1 23 pair Magnifying Desk Lamp magnifying glass fitted to a bal anced swivel arm and desk mount An integral flourescent 3x Lens 120mm2 Magnification Tube 22W Daylight simulation l Model 028 205 28 80 EF f T heElectren amp Lightin equipment for the Entertainment oss Tel 0191 2514363 Cullercoats UK Carriage og ko than 1kg w Fax 5 50 greater than 1kg or gt 30 0191 2522296 Tyne amp Wear e Cheques Postal orders payable to salesGesr co uk Station Road 5 ES NE30 4PQ 2 PCB Production Laminates Copper clad paper Single sided low cost paper aeoe board 100 x 160mm Board 0 100 x 220mm Board 0 62 160 x 233mm Board 1 02 220 x 233mm Board 8 x 12 Board Copper clad glass fibre Single 8 Double 1 6mm 305g m 100 x 160mm Single 1 06 100 x 220mm Single 1 49 160 x 233mm Single E22 220 x 233mm Single 2 88 8 x 12 Single L328 100 x 160mm Double 1 09 100 x 220mm Double 160 x 233mm Double 220 x 233mm Double 8 x 12 Double Photoresist Coated 1 6mm 35 micron Pre coated with a high quality photo resist layer Available in low
274. w ge dlo ad 03 ki l 7 45 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 spe cially designed for video enthusiasts All the projects can be simply constructed and most are suitable for the newcomer to project construction as they are assem bled on stripboard There are faders wipers and effects units which will add sparkle and originality to your video recordings an 60 pages 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 shopping lists of components advice on construction and guidance 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 push button fader computer control interface 12 volt mains power supply Order code PC115 1095 5 45 124 pages ALL PRICES INCLUDE UK POST 8 PACKING Everyday Practical Electronics August 2007 Data and Design PRACTICAL ELECTRONIC
275. where visitors are Please check our website for opening hours and if making a long journey we suggest phoning first to ensure stock availability If ordering on line 90 of orders dispatched within 2 working days Part One By JOHN BECKER A simple signal tracking and display unit for the typical hobbyist workshop ki EPE W25 cope 18AUGO6 l l sx Dual channel analogue Single channel spectrum analysis sx Single channel 8 bit digital On screen control of all functions HE concept for this design is based upon that used in the author s complex Virtual Scope published in EPE Jan 1998 That design used many discrete logic chips to allow a PC compatible computer to show the waveforms of two independent audio signals on its screen Regretably the high speed analogue to digital con verter ADC chip used in that design became obsolete not long after the design was published This design is a much simplified version working under both PIC microcontroller and PC control It al lows not only analogue signals in the general audio range from two sources to be displayed on screen simultane ously but also a waveform analysis of them It can additionally display the logic waveforms generated by external 8 bit digital signals from a single channel The design is intended for mod erately simple signal tracking and display PIC control circuit The circuit diagram for the PIC con trolled master
276. xy encapsulated tags are wound on tiny ferrite cores Included in the IC in the tag are circuits to rectify and filter the volt age from the coil to provide operating power Once sufficient power has been stored the tag transmits its 40 bit ID code by low frequency modulation of the reader s carrier signal For those interested the data stream is Manchester encoded and transmit ted using an ASK amplitude shift keying modulation method As shown on the circuit diagram Fig 1 the interface between the ID 12 Jee Ia DOOR STRIKE ALARM ARMED EA TAMPER SWITCH Fig 3 follow this diagram closely when assembling the PC board The 4 way terminal block CON2 is made by snapping two 2 way blocks together Take care with the orientation of all polarised components reader IC2 and the rest of the circuit is very simple indeed Whenever the reader receives a tag transmission it formats the 40 bit code into five 8 bit bytes and adds a few bytes for synchronisation and integrity checking The entire frame is then transmitted in serial format from pin 9 Three different industry standard transmission formats are supported selectable by connecting pin 7 to various points By grounding this pin our design uses a 9600 bps bits per second ASCII format Atmel microcontroller Serial data from pin 9 of the ID 12 is pumped into pin 2 of an Atmel AT90S2313 microcontroller IC1 Essentially the program r

EPE Online Magazine- August 2007 Vol. 26, No. 7

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