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GADG SII - American Radio History

1. Get started now by building this A Zei G TECHNICAL MANUALS with complete specs on Sanyo computer and professional programs 4 4 DISCOVERY LAB Using it r you construct and test circuits like those used p with computers K M a j SR SM CY gt A t DIGITAL LOGIC PROBE Simplifies analyzing digital circuit operation fully IBM PC compatible computer Now you get it all training for America s fastest growing career opportunity training to service all computers training on the newest total computer system the Sanyo 880 Only NRI can give you the well rounded training you need because only NRI gives you a complete computer system computer monitor disk drive software even test instruments like a digital multimeter and logic probe to work with and keep It all adds up to training that builds the knowledge competence and ability you need to succeed as a computer service specialist Get inside the newest fully IBM PC compatible Sanyo Microcomputer Asan NRI student you ll get total hands on training as you actually build your own latest model Sanyo 880 Series computer from the keyboard up It s fully IBM PC compatible and best of all it runs programs almost twice as fast as an IBM PC As you assemble the Sanyo 880 you ll perform demonstrations and experiments that will give you a total mastery of computer operation and servicing techniques
2. d E kh oo A ai e o e A j 2m ENS f a i B i d P rs oe P P ri p I ai p d SE E3 7 5 l b i 1 5 N CN e E b THE MAGAZINE FOR THE ELECTRONICS ACTIVIST BEES h amu m b ei Y C i B n m sd E It demites the Radiola 2 receiver but its insides are Solid state technology d ny L d 2D W 3 Experimenter s geet you ii use to design specialized supplies for your projects bi Es l F j TR i T m 1 ER Ai b L p 2 JN T DH Add gain to the loop antenna never use a ferrite rod again EHYIN AIRIA AMDI IE u 5 d i J a P i Ew a l L Discover basic trouble shooting and repair techniques using only a multimeter B 5 Sea een a Sg es m eme mem RS Fee ease Cem ES SS RR Compute AC node voltages with our computer BASIC program The budget way to solder a joint with controlled heat T 3 New Wi I FactCards ILU 48784 gv This Issue E 2 50 U S B 2 95 CANADA 1 ES OCTOBER 1987 Vat Em 48784 INCLUDING 12 PAGE az H You say you re already trained in electronics but that you re nor making enough money Well then maybe you don t have an accredited bachelor s degree to prove that your education is up to snuff Check out the Grantham Inde pendent Study B 5 Degree Program It could make a dollars and sen
3. This slick listening post belongs to veteran SWL Kent Magill of Modesto CA Kent s receivers are a Drake SPR4 with a Grunding 1000 as backup He has QsL verifications from 213 different countries and has thus earned a Master DX Centurian award from the North American Shortwave Association a club he has belonged to for the past dozen years EN a CERTIFIED You Can Be 20 000 Technicians VAT Certified BY ISCET WM The International Society Of Certified Electronics Technicians offers permanent certification by administering the CET exam with the FCC recognized communi cations option for 20 A second exam on FCC regulations for a 10 fee is re quired for a Radiotelephone License Upon passing technicians receive both a permanent Radiotelephone Operator Cer tificate and a CET Certificate issued by ISCET ISCET Offers License Renewal ISCET has developed a program for regis tration of those who currently hold a valid Radiotelephone Operator License By sending a completed application a photocopy of your FCC License and 10 your license will be renewed with the assurance of a recognized national tech nicians association behind it For More information Contact ISCET 2708 W Berry Ft Worth TX 76109 817 921 9101 1 i i i j i i j f i i i J MOVING Don t miss a single copy of Hands on Elec tronics Give us ATTACH LABEL Six weeks notice HERE Your ol
4. ________ _ SIDE VIEW ALL OIMENSIONS IN INCHES TUNING CAPACITOR KNOB ASSEMBLY Fig 4 The metal pointer was constructed from a discarded brass plated lid support use a piece of solid brass or copper Drill a inch hole to secure the small radio knob and epoxy the inch shaft insert to the under side of the dial pointer to attach to the shaft to the tuning capacitor 2861 H38O100 e HANDS ON ELECTRONICS C gt TEMPERATURE CONTROLLED SOLDERING STATION By Ladislav Hala Avoid destroying sensitive components during soldering with this soldering iron temperature controller ANY TIMES WHEN YOU SOLDER YOUR SOLDERING iron is kept switched on for unnecessarily long peri ods consuming energy and allowing the soldering iron tip to burn and develop a buildup of oxide All because you didn t want to face a cold iron and have to wait for about 3 minutes while the tip heats to the proper temperature Buying a lower wattage iron may solve some of the prob lems but new problems arise when you want to solder some heavy duty component such as a filter capacitor to a huge bus terminal setting the stage for creating cold connections If you ve ever tried to troubleshoot some instrument in which a cold solder joint was at the root of the problem you know how difficult such defects are to locate Therefore the only possible way to satisfy all your needs is to buy a temperature controller for you
5. MAGNETIC FIELD Ec A Flr TON uA ELECTRIC FIELD MAGNETIC FIELD Fig 1 Radio and TV waves are electro magnetic EM waves exactly like light infrared and ultraviolet consisting of two mutually perpendicular oscillating fields electric and magnetic shown in A If as shown in B at a great distance from the center we take a look at a small slice of the advancing wave front we would be able to observe the electric and magnetic field vectors at right angles to each other would be horizontally polarized Those designations are especially con venient because they also tell us the type of antenna used vertical antennas pro duce vertically polarized signals while horizontal antennas produce horizontally polarized signals Some texts erroneously state that antennas will not pick up signals of the opposite polarity That claim is non sense although a 20 dB or so loss might be observed at VHF through microwave frequencies Although cross polarization might be a factor at VHF it is not even a consideration in the HF bands An EM wave travels at the speed of light designated by the letter c 7 which is about 186 000 miles per second or 300 000 000 meters per second if you prefer metric in a vacuum To put the velocity in perspective a radio signal ori ginating on the Sun s surface would reach Earth in about eight minutes terrestrial radio signal can travel around the Earth s
6. Se n The grimy main tuning capacitor was bath ed in mineral spirits to loosen up the encrusted dirt and dust followed by a compressed air blow dry ened and decomposed so I needed re placements I was able to find grommets of the right size in a 99 cent Radio Shack assortment but had a heck of a time getting them into the old holes Modern vinyl is quite a bit suffer than the old time soft rubber Once the tuning capacitor was re mounted on the chassis restrung the dial cords for the main tuning and bandspread controls had made a careful reference sketch of the stringing system prior to dismantling it After reassembly every thing worked fine except that one of the cords tended to slip now and then Apparently I had done too good a job of cleaning and polishing one of the con trol shafts It was a little too smooth and couldn t get good enough grip on the cord it was supposed to drive So slipping the dial cord loops temporarily to one side I rubbed the contact area of the shaft with stick paraffin That seems to have cleared up the difficulty After reinstalling the dial plate and pointers was ready to reassemble the chassis to the wrap around cabinet front panel But before doing that while switches and controls were sull easily ac cessible I treated them all with a liberal application of contact cleaner spray then vigorously operated each one several times through its full range T
7. fuzzy VCR pic ture is given as slow recording speed or normal low resolution of oi system It further explains all VCR pictures are grainy on a high reso lution system So be prepared if you tote this high tech tube home to give serious consi deration to upgrading all your equip ment in order to be worthy of the 625 One video add on which showed off the 625 s touted high resolution per formance to good effect was a Hitachi color video printer the VY 100A Connected via the front panel video CHICAGO CES Cont from p 7 Omaha NE 68106 lt looks like a desk lamp in that it has a heavy base and a pole But this gadget is no lamp Instead the device has a lightweight but heavy appearing chrome ball a little over an inch in diameter that s balanced magnetically underneath The Levitator s arching pole The ball is suspended in mid air about an inch away from the arch at its nearest point It creates an eerie effect and allows its owner to have something different OCTOBER 1987 time In setting the time for example if we accidentally went beyond the proper hour or minute we had to start all over again Not start all over again adjusting the time but begin again with the entire process of setting the instruments vari ous functions in rigid sequence Because a miscue in setting time couldn t be aborted and as the watch is told which function to display for adjust
8. Bookshelf Loudspeakers You may want to take these off Bose s shelf and put them on yours Especially if you re seeking good performance from small speakers at a modest 299 per pair suggested list price The speakers mea sure IO x 15 x 7 inches and weigh only 12 pounds each Like the other models in the series the 2 2 loudspeakers feature innovative tech nology for precisely controlled sound ra diation allowing listeners to hear balanced stereo from nearly anywhere in a listening room called the Stereo Targeting system that new technology is used in all Point Two speakers A driver array de signed in conjunction with the speakers cabinet and crossover network directs sound into the middle of the room As a listener moves toward one speaker its loudness actually decreases relative to CIRCLE 63 ON FREE INFORMATION CARD that of the other so that they remain in balance The speaker s directional charac teristics combined with its controlled output allow maintenance of a stable ster eo image regardless of where the listener sits or stands Consistent performance is assured by Bose s exclusive Syncom Il computerized driver testing and matching system In addition an advanced bass tuning technique adds full frequency realism by precisely controlling an air cushion inside each speaker cabinet The result is deep realistic sounding bass without a large bulky cabinet or extra amplifier power The system configu
9. Sd 4 3QON TWILINTs Sid 4HOLOnGQNI Od OO0PZ OLO9 NEHL T gt IN JI ON 61032npuT jo J qunu 1e3ua LNdNI S12 AO 03 KULEOEOL IEEE OO VOV X x NOILOSS HOLODQONI assa eee eee vy OE eu yes I LX3N q I NRI N3 V T NI N3 V TA I N3 N3 M I N3 N3 U q CI N3 NI V I N3 NI V TA Y NI NIOM I NI NIOW TA M TA OYLE ansoo JN OL T I NOJ 4a gt 4 SNTWAu SEd i4 S3gQON IYNIJ Sd A JAQON IWILINI Std aNOLI2MWdW2 0d OPZZ OLO9 N3Hl T gt ON JI DN s1O041I2ede 2 jo 1iequnu 1e34u3 L dNI S12 HOLIOWdWMO sev eee eee ee eee ee I A aj Mp MOERORE AERE NOILOSS I LX3N TA O NI N3 V O NI N3 V TA O N3 N3 MV O N3 N3 M JA O N3 NIO V O N3 NI V TA O NI NID MV O NI NIDY OPLE 8hSO5 ON OL T I NOJ 44 504W SATWA SEd a 30ON WNIJ 2d 4 3Q0ON IWILINIu Sid 4AHOL2DnQ0NOO S d 080Z OLO9 N3HL T gt ON JI ON 1032npuoo jo Jequwnu ie3u3 LNdNI S12 A KRKKRKRKKKRKRKERREERKRRRKKKKKKKRR NOI LIES HOLODnQNOO nnngngxggEgggRRKKKKKKKRK I LX3N TA O NI N3 V O NI N3 M TA O N3 N3 M O N3 N3 M TA O N3 NI M O N3 NI V TA O NI NI V O NI NI M d T sw Ta ObLE 8nso5 JN OL T I HO 4a suqo 3fm1qWA SEd n 3OON IWVNIJ Sid 4 3QGON IVILINI Std 4HOLSIS3NH SOd OS6T OLOD N3HIl I gt ON JI 2N SJO3STSel1 JO Jaqunu 1e3U3 LAdNI S312 NOT LIAS HOLSISSMH seueev yey ve eee vy s
10. appearance two dummy tubes are mounted under the slotted area in the front panel Cut a piece of white pine 2 x 4 inches Drill two large side by side tube mounting holes The holes should be just large enough so that the prongs of the tubes will fit down inside Cement the bottom side of the tubes into the mounting holes Place the tubes directly under the slotted area Cement the tube board to the bottom panel If you wish add a filament transformer to the project and power up the filaments of the vacuum tubes only The glow The radio pulls 10 mA with the volume turned down If the current measurement is over 17 20 mA suspect incorrect wir ing or a leaky transistor or IC Critical voltage and current measurements should help locate the defective component from the tubes with the attending heat will add the at mosphere Grandpa enjoyed years ago The Final Touches Nothing can give Grandpa s Antique Radio that old fash ioned appearance more than radio knobs If you can not come up with some antiquated knobs simply make them The dial of the main tuning capacitor was constructed of a piece of white plastic An aged yellow color would be better Lines were drawn within the plastic surface with a flat blade of a soldering iron Grind the soldering iron point flat on both sides Use a metal ruler or straight edge to gouge various lines in the dial assembly Sand or file down the raised edges Place black paint in the grooved lin
11. Amazing Devices I5 Antique Electronic Supply 105 6 CORE EE 21 7 Cooks Institute 15 8 Digi Key ice ca cc ce eae 7 Electronic Tech Today CV3 10 Electronics Book Club 3 14 Fluke Manufacturing 6 Grantham Col of Engineering CV2 9 Heat eee Re 24 ISCET DE OUO ES 27 12 MCM Electronics 23 McGraw Hill Continuing Education Series 99 II Mouser et EEN 7 NRI ee eee sas 11 29 Pacific Cable 5 Wind Jammer CV4 WEL S THINK TANK Continued from page 96 The output of the astable at pin 4 of Ulb is fed to the input of a monostable multi vibrator consisting of the second pair of gates Ulc and Uld R7 and C3 are the timing components they set the length of the positive output pulse of the monosta ble at a little more than half a second The monostable is triggered by each positive going input it receives from the astable The output from the monostable there fore consists of a series of short pulses the interval between the pulses being con trolled using S2 The output of the monostable at pin 11 controls a relay by way of Ql which is configured as an emitter follower buffer stage The projector is controlled via the normally open contacts of relay K1 When the output of the monostable goes positive the relay contacts close trigger ACTIVE ANTENNA Continued from page 79
12. BP152 INTRO TO 2 80 MACHINE CODE 5 95 Speed up your programs They may be harder to write but ds worth learning how Some demo programs are included Electronics amp implificd Crystal Set Construction BP121 OESIGN A MAKE YOUR OWN PC BOARDS 5 75 Ev erything you need to know belote you make printed circud boards for your projects ECTS 6 95 Detads ot how to interlace many popular home computers with MIDI mus sysler user onenled IC s Electronics Paperback Books BP140 DIGITAL iC EQUIVALENTS ANO PIN CONNECTIONS 12 50 312 pages 10 in shows equivs amp pin connections lor popular BP108 INTERNA TIONAL DIODE EQUIVALENTS GUIDE 5 75 Full inter changeability data and Characteristics for diodes Zeners LEDs Dacs Trace and more BP146 THE PRE eg BASIC BOOK 6 95 BP187 REFER A book on the BASIC ENCE GUIDE TO programming tor those AMSTRAD WORD PRO who have not yet bough CESSING 14 95 a computer as well as Everything you need Io those who have Iroubie know about using these learning how to program machines further amp iectronic 29 Senpiec i e en Circuits for the Amateur Band Lov i Calculations and Computer hariols Communis ES Formulae Control ot ViG 20 RRC Micro i Robots amp Sean Hegttor E ei i i H 8P179 ELE BP105 ANTENNA WHITES WHITE S PB144 FURTHER TRONIC CIRCUITS FOR B PROJECTS 5 00 RADI
13. FUSE 117V tance measurement to the same point in the normal channel Blown Fuses If the fuses in the amplifier continually blow at power up the first step is to determine which one opens up Large amplifiers may have separate fuses for power lines each stereo channel or speakers or maybe all three Suspect a leaky or shorted component in the low voltage power supply or output circuits when the AC power line fuse keeps blowing Check the output transistor or IC when the fuse will not hold in a certain stereo channel Too much volume or DC voltage applied to the speaker fuse may cause the fuse to open up Remove the fuses or disconnect the power source from the power output components when the power line fuse fails Check each diode or the bridge rectifier in the low voltage power supply for leakage with the diode test of the DMM again freeing one end of the unit before testing Take a resistance measurement across the main filter ca pacitor to determine if the capacitor or connecting circuits are leaky Do not overlook a shorted power transformer Unsolder the secondary leads of the transformer from the circuit for leakage tests If the fuse opens or transformer appears hot with the secondary wires removed suspect a shorted transformer Go directly to the output transistors and IC components and test for leakage when the power supply is overloaded or the channel fuse opens up Excessive Hum Suspect the main filter capacitor
14. IO FOR 45 00 TOYO TF92115A New 115 Vac cooling fan 3 5 8 square X I deep Metal housing 5 blade impeller CAT SCFE 115 8 50 each 10 for 75 00 26 ICs including 6502A 6560 2 ea 6522 4J ea 8128 A ea 901486 j ea 2114 Not guaranteed but great for replacement or experimentation CAT VIC 20 15 00 each Mouser 25LMO44 3 Highly sensitive E mini microphone 6 wire leads 39 dia X 27 high Omni directional Operates on 2 10 Vdc Less than 1 mA 1K impedance 50 to 8 K Hz range CAT MKE 1 1 00 EACH 12VDC 4PDT RELAY Guardian 1315P 5 amp contacts i 150 ohm coil P C terminals oh Clear plastic dustcover bos CAT 4PRLY 12PC 3 50 each TTO for 30 00 P O BOX 567 VAN NUYS CA 91408 800 826 5432 Tou MINIMUM ORDERS 1 0 90 800 826 5432 EE roo SA Tan INFO 818 904 0524 NOCODI FAX 818 781 2653 ImCLUDE SUFPICIEAT CIRCLE 5 ON FREE INFORMATION CARD 4861 H38O100 HANDS ON ELECTRONICS wech ds COO SHELF So you Bought a Shortwave Radio By Gerry L Dexter How often is there help for the person starting in a new hobby especially a hob by like ham radio If you need help this text may be of use The book places spe cial emphasis on making the reader aware of the audio warp experienced by first time shortwave radio listeners and help ing the reader over that obstacle Rather than bombard the reader with reams of information which he c
15. Massapequa NY Building Metal Locators A Treasure Hunter s Project Book By Charles D Rakes With these electronics projects the fun doesn t end after the construction is com plete it S only beginning With the metal detectors you ll build using this one of a kind project guide you ll be ready to get started in a hobby that is exciting chal lenging and potentially profitable If you ve ever dreamed of discovering a buried treasure stop dreaming and open this guide of schematic diagrams work in progress drawings and photos com plete part lists step by step instruc tions everything you ll need to build the essential piece of equipment needed for a BUI gw METAL LOCATORS A TREASURE HLINTER S PROJECT BOOK CIRCLE 54 ON FREE INFORMATION CARD successful treasure hunt a metal detec tor An exciting low cost alternative to expensive commercially made metal lo cators the detectors included in this unique project guide will locate anything from coins and jewelry to gold and silver and can be built quickly and easily by any electronics enthusiast With Charles Rakes guidance in de signing and building metal detectors you ll be ready to hit the beach old aban doned home sites old carnival sites rec reational parks playgrounds racetracks your own backyard or wherever hidden or lost valuables might be found Just some of the various types of detectors covered include frequenc
16. NS W T O NI N3N Y O Na Na Y oe I LX3N OZLSE C LX3N 0062 LNINd O9SE O T C NSE Y gt O O C Na Y 0682 ul o n S 1d S0O0d M NIS 9WH vu LNINd OSSE T C NS Y T C NI Y T C NI Y 0882 T Sta N31 STd SLHOIM ld Ober O C N3 V O C NI M O C NI Y 024982 9NV SHIS Id DE St IN OL I C NOJ 0982 u 7 34 S d N3HL O gt ONW JI OZSE OL N3 N3 NI NI OL IA IA HA HA NAHL NA lt NI JI osez a 347 0d OTSE OL8E anso9 Orez OST ONW ONW N3HLl O gt O IN I M JI oose 2N OL I I MO OE97 Id OGI w O IN I V l IN I V NLIM ONY Dt 4 S9e15eq BIONY 3SMHd Spd O7 97 OISE OLOS OLZ ONW NAHI O gt I IN ID M QNV O O IN I WM JI ogre 2 S310A a nLINOWW SEd OTOZ OISE OLOO 081 ONY NAHI O gt O IN I V QNV O I IN I WM JI OLbEe e 3dON 3AILISOd Sid 0082 OISE OLOS 06 ONW NAHL O lt I IN I V QNV O O IN ID M JI 09v 4 30 ON 3AILWO3N SId 06242 OTSE OLOO O ONY NAHL O lt O IN I V QNV O T IN I Y JI OStE aSAl4 SOd O9L7 IN I 9VHN3 OWN OFPPEe 09672 OLOD N3HL I gt ON AI OLLZ edit e or CP V Wuelbefanne ide ON FESAI 3O 19qunu 193ua LndNI S12 0922 E OSLZ ure yqa seerl 3red mad S weiss o Es MR e b eie ssyyysy yysssssssssss NOILOSS 324n0S AOWLION LN30N3d3QNI sexsssssssys id 31ed Aieujpbeu 1 IN I V SMIS Sid O6tt 0222 33ed eei O IN ID V SHLS Sid OS tEt I LX3N OILZ u u S d N3HI O gt I IN I V JI OLEE JA O N2 N3
17. The RF and regen FET transistors Q1 and Q2 amplify and detect the RF signal for the audio chip IC1 The regeneration circuit is centered about FET transistor Q2 Radio frequency signals amplified by QI are coupled to coil L2 The tuned circuit is composed of L2 and tuning capacitor C3 which tunes the tank circuit and selects the desired station frequency The gate bias for the detector stage of Q2 is developed by a grid leak combination consisting of C4 and R3 That combination should be called a gate leak but it s too late in the radio game to coin new phrases Regenerative feedback is provided by connecting the source S terminal to the 6 turn tap of L2 The regeneration is controlled by varying the voltage on the drain terminal of Q2 with regen control R4 Now the detected audio signal from the drain terminal is capacity coupled by way of C7 to volume control R5 TO Q1 TO Q2 Fig 2 Coils L1 and L2 are i wound on a inch diameter e ferrite rod which may be cut to ei DEI size from a longer rod Mark a groove around the rod with a hacksaw or file and it will snap in two when tapped Refer to text for coil winding information The controlled audio signal is applied to pin 3 of audio amplifier Ul A stereo earphone jack Jl is connected through electrolytic capacitor CIO to pin 5 of Ul Although Grandpa always used a pair of earphones he called them cans the LM386 power amplifier will drive a small PM
18. This block diagram illustrates the finished basic circuit with the box representing the circuit board If your circuit is to include the neon lamp indicator and switch S2 connect those components to the circuit guided by Fig 2 If your circuit is to include the neon lamp indicator and switch S2 connect those components to the circuit guided by Fig 2 For safety reasons it should be remembered that the hot side of the line cord must be connected to the unit through switch SI A 3 prong line cord must be used with the third wire connecting the ground of the outlet with the ground of SOI to which the soldering iron is connected It is advisable to use a plastic or some other non metallic box to house the project thereby arresting any possible shock hazard If you use a metal box be sure that the box ts correctly grounded via the line cord ground lead and that the AC outlet is properly grounded as well Otherwise you H be exposing yourself to almost certain shock hazard Since the circuit described here does not use any isolation trans former all components must be assumed to be hot con ducting 117 volts AC Therefore it s advisable not to operate the unit without its case If it is necessary the operate the circuit outside of its enclosure be sure to stick to the one hand rule which those of you with an military background in electronics are surely familiar with The one hand rule says that the unit should be ope
19. Usually a leaky or open transistor like that indicated in Fig 2 prevents the relay from operating Make voltage and resistance measurements on the suspected component not ing whether your readings match those specified by the manu facturer POWER AMPLIF ER f DARLINGTG i POWER PAGK Ui F OPEN Voltage and Resistance Measurements 51 3V 250712 TRANSISTOR Most audio transistors and IC s are contained in directly coupled DC circuits The collector or emitter terminals of a driver transistor may be tied directly to the the output device another transistor or an IC as shown in Fig 3 With a leaky or open transistor the voltages may be incor rect on the transistors or C s in that audio channel First make in circuit transistor tests with the diode transistor test of the DMM or a transistor tester defective IC may be located by using voltage and resistance measure ments or through audio signal tracing methods Now take critical voltage and resistance measurements to help locate the defective component Fig 2 The relay malfunction may be caused by dirty contacts Always have the correct schematic handy before trying or an open coil winding Check transistor and IC controlled to take critical voltage measurements It is difficult to take osten apii sadi pie ile rin da accurate voltage and resistance measurements without a dia gram You may find operating voltages listed on compo nents of only one audio channel
20. With the advent of the transistor age miniaturization became all he rage so the solid core antenna was born putting the air core on the shelf 2861 H38OLO2O zl ao HANDS ON ELECTRONICS zl o Despite its benefits the loop antenna has tended to remain fairly obscure The reason for this is the cost and difficulty of mass producing wooden frames and coils under tension and the generally cumbersome and not too attractive appearance of the device The Techniloop was designed to overcome those problems The result is an easy to build efficient loop that is also reasonably attractive Description As can be seen from the photos the wooden frame has been eliminated That is made possible by the use of flat 16 wire ribbon cable as the winding of the loop coil The coil is formed by connecting the ends of the length of cable back into the starts That is done by terminating both ends of the cable via IDC insulation displacement con nector plugs and sockets on a printed circuit which cross connects the cable ends A 3 position 6 pole switch on the PCB allows three series parallel cross coupling combinations to give all half or a quarter the number of turns while always using all the wire for maximum efficiency The l6 way cable is connected as 8 way cable by parallel ing to increase the coil Q and to simplify the PCB track layout There are actually seven pairs and one single wire used in the main loop with the remainin
21. You ll do program ming in BASIC language even run and interpret essential diagnostic software Understanding you get only through experience You need no previous knowledge to succeed with NRI You start with the basics rapidly building on the fundamen tals of electronics with bite size lessons You perform hands on experiments with your NRI Discovery Lab and then move on to master advanced concepts like digital logic microprocessors and computer memories Learn at home in your spare time You train in your own home at your own convenience backed at all times by your own NRI instructor and the entire NRI staff of educators and student service support people They re always ready to give you guidance follow your progress and help you over the rough spots to keep you moving toward your goal 100 page free catalog tells more send today Send the postage paid reply card today for NRI s 100 page catalog that gives all the facts about computer training plus career training in robotics data com munications TV audio video servicing and many other fields If the card is missing write to NRI at the address below A AN McGraw Hill Continuing Education Center 3939 Wisconsin Avenue Washington DC 20016 M We ll give you tomorrow Hi 861 H3EOLDO N HANDS ON ELECTRONICS NEW PRODUCT SHOWCASE Continued from page 8 range of digital applications in research production or serv
22. consider the loop a worthwhile accessory This close up view shows how the ends of the loop coil are folded and termin ated in the IDC connectors Note the strips holding the wire in place against the loop 286 H38OLOO e o GRANDPA S ANTIQUE RADIO Continued from page 33 PARTS LIST FOR GRANDPA S ANTIQUE RADIO B1 volt transistor radio battery BP1 BP2 Multi way binding post one red one black C1 C2 C4 01 F 100 WVDC ceramic disc capacitor C3 365 pF miniature variable capacitor Coleco A1 233 Circuit Specialists A1 233 or evivalent C5 05 uF 100 WVDC ceramic disc capacitor C6 25 LF 100 WVDC ceramic disc capacitor C7 C3 10 uF 15 WVDC electrolytic capacitor C9 470 pF 15 WVDC electrolytic capacitor C10 47 4F 15 WVDC electrolytic capacitor U1 LM386 low voltage 7 watt audio power amplifier integrated circuit Ji Earphone jack miniature type Q1 Q2 MPF102 FET transistor Radio Shack Circuit Spezialist or evivalent R1 4700 ohm 2 watt resistor R2 470 ohm 2 watt resistor R3 22 000 ohm V2 watt resistor R4 50 000 ohm potentiometer with SPST switch S1 R5 10 000 ohm audio taper potentiometer H6 10 ohrn v2 watt resistor Perfboard Radio Shack 276 162 8 pin IC socket 8 to 30 ohm stereo headphones 9 volt battery connector hookup wire cabinet material scrap brass white pine wood flathead screws paint dummy tubes knobs etc
23. duplication of commercial recordings LPs and CDs This sounds like a rerun of the rec ord industry s response to the intro duction of audio cassettes The music merchandisers were fearful that home recording would destroy the record in dustry with piracy running wild and consumers building their music collec tions with illegal copies instead of the bonafide record label products A certain degree of genuine piracy does exist today actively fought by the record industry trade association the OCTOBER 1987 U S Justice Department and the Fed eral Bureau of Investigation Whether home taping constitutes piracy is a philosophical and pocketbook ques tion but whatever the Situation the record industry is hardly on its last legs A special anti copy microchip in DAT decks would surely crimp that new market create an entire under ground industry for devices to abort the anti piracy chip and maybe most importantly leave the consumer out in the cold as the electronics and record industries battle it out over profits and market protection A long term perspective which in American corporations seems to mean deciding what to have for lunch that day and a little less panic in the execu tive suites should suggest to all inter ested parties that the best approach is to go with the DAT flow But beyond or maybe beneath weighty questions of market develop ment and protective legislation and the future o
24. gr load current l is FT determined solely by qo e the input voltage T The input voltage is a stable DC reference voltage source shown as a battery in the diagram As with the conversion circuits discussed above the load current I is determined solely by the input voltage V and resistor R1 R has no affect and is given by I V R1 Since both the input voltage and R1 have fixed values in the circuit I also has a constant unvarying value Even if the load resistance changes drastically the current flowing through the load remains virtually unchanged as long as V and R1 are held constant Polarity Splitter Finally we will look at an op amp circuit for splitting a single ended power supply into a dual polarity power sup ply The value of such a circuit should be obvious to any electronics hobbyist The circuit shown in Fig 9 converts a single ended power supply into a dual polarity power source with an artificial floating ground As with any other single to dual polarity converter the output common ground should never be shorted to true Earth ground That would almost certainly damage the semiconductors in either the converter or load circuit and it could create a serious shock hazard REGULATED Voyr O COMMON REGULATED VIN REGULATED VouT Fig 9 The polarity spiitter allows a single ended power supply to be used as a dual polarity power supply with an artificial floatin
25. o user instant access to over 100 commonly needed routines Never again will pro grammers be forced to waste valuable time wading through manuals or tutorials in search of a routine that reads a name from the keyboard displays a message on the screen or does some other common task To making it much more than just a subroutine sourcebook the author gives real world interaction with the software tools that assembly language program mers use Step by step procedures are demonstrated for using the IBM and Mi crosoft Macro Assemblers as well as the full details on the EDLIN line editor SYMDEB and DEBUG debuggers and the LINK and EXE2BIN utilities Also included is a summary of the entire 8086 8088 and 80286 microprocessor instruc tion sets arranged in logical groups for quick learning and easy reference Assemblv Language Subroutines for MS DOS Computers contains 350 pages costing 19 60 in paperback and 27 95 as a hardbound from Tab Books Inc PO Box 40 Blue Ridge Summit PA 17214 Tel 717 794 2191 1001 Things to Do with Your Amiga By Mark Sawusch and Dave Prochnow How about a book that puts the full applications potential of the Amiga with in the reach of every one of its users This book is a collection of more than 1000 ways for Amiga owners to take advantage of the unique features of one of today s most sophisticated micros for uses rang ing from household record keeping and budgeting to investment anal
26. of Ul The reference at the non inverting input of Ul is determined by resistor RI and Zener diode DI A portion of the output voltage is fed back to the op amp s inverting input through a voltage divider network made up of resistors R2 and R3 The operation of that circuit is much the same as that of the circuit in Fig 1 Now what about the negative half of the circuit Actu ally the negative voltage regulator is more or less a mirror image of the positive regulator with the polarities reversed To reduce the parts count and to ensure that the dual polarity outputs are symmetrical a slight modification to the circuit is in order as illustrated in Fig 4 the negative section of our dual polarity regulator circuit FROM REQUIRED V Fig 4 The negative voltage regulator is more or less a mir ror image of the pos itive regulator with polarities reversed To reduce the parts count and ensure sym metrical dual polarity outputs a Slight mod ification to the cir cuit is necessary UNREGULATED The negative regulator circuit consists of U2 Q2 R4 RS R6 and R7 Note that the Zener diode isn t needed to set a reference voltage because the positive regulated output is used as the reference voltage source for the negative regu lator Also note that Q2 is a PNP transistor to account for the change of polarity Resistor R7 references the non inverting input of U2 to ground Resistors R4 and R6 are equal in value a
27. reserved for show business But it shouldn t be denied that the Chicago show unveiled little in the way of genuine innovation Instead the emphasis was on fashion in electronics All kinds of companies are marketing pastel colored TV sets portable sound systems calculators and so forth It seems a little silly and considered in light of the confidence exhibited at past shows maybe a little desperate Still it wasn t all fashion frou frou and while spectacular innovations with the exception of the controversial digital audio tape or DAT were rare CES this year did unveil some solid advances in consumer electronics Panasonic Personal Stereo One of the most impressive develop ments amid ali the high fashion elec tronics was a group of audio products featuring enhanced bass The first to catch our attention was from Pana sonic 1 Panasonic Way Secaucus NJ Page 6 GADGET Panasonic Portable Stereo System 07094 the RX SA79 Personal Stereo with XBS extra bass system Not only has this portable unit broken the two battery barrier it s powered by a single AA but it has a built in charger and power cell The RX SA 79 has all the standard features of personal stereo systems like an auto reverse tape deck with Dolby noise reduction and FM radio But what makes it noteworthy is Pana sonic s XBS To our ears the bass this player de livers sounds at least as rich as th
28. timekeeping mode In the 24 hour mode 2AH appears in place of the AM PM designation There s a final adjustment on the map face in the lower left corner This is a boxed symbol of the sun with the initials DST for daylight saving time and summer time below it If the home zone for the clock is on daylight saving time a small sun appears above the day of the week in the time display along with the corrected adjusted time If the user should go to another time zone on the indicator then return to the home zone the time shown will not be adjusted for daylight saving So a second touch to the summer time box is necessary to bring up the correct time again This feature our publisher felt was a bit fancy for its own good It also meant that at least during the summer the Seiko Worid Time Touch Sensor might be better designated the World Time Two Touch Sensor Power for all this global time spanning is pro vided by two 1 5V AA batteries Seiko offers the usual one year limited warranty on the product Handsome simple to operate and in genious the World Time Touch Sensor would bring a touch of class to just about anyone s world G A GADGET Page 3 2861 H38O01200 A He HANDS ON ELECTRONICS e e Unsilent Partners AR POWERED PARTNERS Manu factured by Teledyne Acoustic Re search 330 Turnpike St Canton MA 02021 Price 339 95 As the market for consumer electronics
29. tweezer and selector switch brush The kit model K 55 is priced at 54 00 For further information and liter ature write to Jonard Industries Corp 134 Marbledale Road Tuckahoe NY 10707 Racing Pulse Your heart may skip a beat over this pulse generator with repetition rate varia ble from Hz to I25MHz and a choice of fixed 2 1 5 or I ns risetimes The PM5785 has a wide choice of external trigger and gate functions full control of CIRCLE 65 ON FREE INFORMATION CARD pulse repetition rate duration and delay a presettable high speed burst option and dual normal complementary output with a choice of bipolar positive or negative pulses Setting error indicators simplify operation The choice of fixed high speed transi tion times and output pulse forms makes the PM5785 very well suited to a wide Continued on page 12 ere TOR uM MR Ce TEE DI E SET TTC ER e UM MM a BC wer p 4 M e d C 8088 1 Ah OM du A H3 r3 T Train with NRI for a high paying SANYO COMPUTER 8 CPU double sided disk drive MONITOR High resolution 256K RAM 4 77 MHz and 8 n screen displays crisp DIGITAL MULTIMETER MHz turbo speed Ee graphics Professional test instrument TRITT for quick and easy measurements LESSONS Clear well illustrated texts build your understanding of com puters step by step DISK SOFTWARE including MS DOS GW BASIC WordStar and CalcStar
30. very low overscan black level compensation and 95 per cent DC restoration Even if you re not a video technician this sounds as if it should result in a very fine picture So how does the Proton 625 perform First GADGET had to set this moni tor receiver up and that s when we were reminded of an important differ ence between this kind of unit and a mere television set With a TV the device is removed from its packing box plugged in turned on and it works With a moni tor receiver however there s much necessary fiddling and adjusting before anything appears on the screen We spent around 45 minutes trying to con nect the Proton to a standard cable hook up sans scrambled signals and finally called on the assistance of a video producer technician Once functioning the initial recep tion wasn t all that super its picture was grainy and oddly indistinct How ever as the 625 warmed up the image became crisper and altogether sharper Using the 3 3 loudspeakers we were also disappointed in the monitor re ceiver s audio adjustment sensitivity Perhaps we mistuned each speaker s input sensitivity control but for whatever reason neither the front panel nor remote volume adjustment was very responsive The audio level was either a shade too loud or else not loud enough We never did find the happy medium Although the Proton 313 speakers are shielded for magnetic interference the same series 3
31. which you ll surely recognize as a push pull amplifier The input to the push pull feeding SPKR1 is controlled by R4 which serves as a volume control Take a look at Fig I Note that only one channel is shown For stereo operation two such circuits are required The ap plied signal is fed to the inverting input of Ul a 741 op amp that s set up as an ampli fier buffer The output of U1 is fed to the common base connections of QI and Q2 which you ll surely recognize as a push pull amplifier The input to the push pull feeding SPKRI1 is controlled by R4 which serves as a volume control In putting the project together if stereo operation is desired we recommend that a dual gang potentiometer be used for R4 and wire them so that as one side in creases the other decreases In that way the volume controls also serve as balance controls and SI which is the on off switch can be mounted to the back of the pots Well Sam your copy of the FIPS book is in the mails and I hope that you and your wife enjoy it Touch Switch ve derived a good deal of pleasure and satisfaction out of my electronics hobby so it s indeed a pleasure to give some back do remember chuckling over the original FIPS articles when they were published and it will be a delight to see them again I do hope this circuit wins me a copy writes Ted Welsh of San An tonio TX With no moving parts to wear out the circuit shown in Fig 2 give
32. 10 October 1987 Larry Steckler EHF CET Editor In Chief amp Publisher Art Kleiman editorial director Julian S Martin KA2GUN editor Robert A Young associate editor Herb Friedman W2ZLF associate editor John J Yacono associate editor Brian C Fenton associate editor Carl Laron WB2SLR associate editor Byron G Wels K2AVB associate editor M Harvey Gernsback contributing editor Teri Scaduto Wilson editorial assistant Ruby M Yee production director Karen S Tucker production manager Robert A W Lowndes editorial associate Marcella Amoroso production assistant Jacqueline P Cheeseboro circulation director Arline R Fishman advertising director BUSINESS AND EDITORIAL OFFICES Gernsback Publications Inc 500 B Bi County Boulevard Farmingdale NY 11735 516 293 3000 President Larry Steckler Vice president Cathy Steckler NATIONAL ADVERTISING SALES For Advertising Inquiries Only Joe Shere MIDWEST PACIFIC 1507 Bonnie Doone Terrace Corona Del Mar CA 92625 714 760 8697 Larry Steckler Publisher 500 B Bi County Boulevard Farmingdale NY 11735 516 293 3000 Composition by Cover photography by Mates Graphics Herb Friedman Hands on Electronics ISSN 0743 2968 Published monthiy by Gernsback Publications Inc 500 8 Bi County Boulevard Farm ingdate NY 11735 Second Class postage paid at Farmingdale NY and at additional mailing offices One year twelve iSsues Subscrip lion ta
33. 36 as you Say but a negative 36 Thanks for the correction For those of you interested the head ing for this letter was taken from Alice In Wonderland idea Potpourri would like to see Some more home brew projects that would be helpful on the test bench like a stable function generator and possibly a triggered pulse generator There are plenty of logic probes in kit form already but perhaps you could throw one in to help complete my digital lab have copied such proj ects from some TAB books and several other books have collected or checked out from my local library Some of cir cuits and specifications are rather old in design and components So thought you guys might be able to come up with better circuits and innovations of the day Anyway thanks for the last hold out from tota computer saturation How about some ham radio stuff think that Packett Radio is something that even the computer fans of your magazine would enjoy Thanks for your time P F C Paris KY We d like to see more of everything The Great PC Clone Contest is still on so get those manuscripts in Whether its about serious test equipment fun proj ects or information for the fast times we i LETTER m Hands on Electronics 500B Bi County Boulevard Farmingdale New York 11755 live in send us your stuff Just think not only do you get paid upon acceptance get a chance to see your name in print and have
34. ARCHIVE 5 95 CUITS Book 2 Presents the powerful 5 75 More useful cit dalabase for the Sincia culls None of these OL Step by step ap poset duplicate Those proach includes practical in 1 of tus senes examples OUTSIDE USA amp CANADA Multiply Shipping by 2 for sea mail Multiply Shipping by 4 for air mail Total price of merchandise Sales Tax New York State Residents only Shipping see chart All payments must be in U S funds Number of books ordered C A Total Enclosed A place to live your fantasies A place to free your soul To cozy up to the Caribbean sun To dance among a thousand stars to the rhythms of steel drums To play on sparkling white and ink sand beaches o discover the underwater radise of the reefs o find a new friend and share the irtimacies of a sensuous night To come alive and live To remember for a lifetime 6 days and 6 nights From 625 Reservations toll free 1 800 327 2600 In Florida 305 373 2090 Windjammer Barefoot Cuve Pest Office Box 120 Miami Beach Florida 33119
35. Controls In One With the universal remote control from R L Drake you would no longer have to keep track of separate units for television videocassette recorder and other audio video equipment The Model PRC U allows the user to operate up to three different remote con trolled components from one device By consolidating the functions of three re mote control units in one this product solves the problem of multiple modules In addition to being versatile Drake s universal remote control is extremely easy to program The user simply flips the LEARN switch and places the Drake device against the component s original remote control unit so they re facing each other He then presses the function he wants to program such as on off change channel or fast forward on the Drake unit and on the original control Every time that pro cess is completed Drake s control flashes a light to indicate it has learned the function The user follows that procedure for each function he wants the Drake re mote control to perform Drake s unit can m CIRCLE 66 ON FREE INFORMATION CARD learn any function that s on the original remote control unit And with Al function keys Drake s device can operate even the most sophisticated consumer electronics components The Drake universal remote control has a 30 foot range and can be used with up to three remote controlled products as long as they re infrared not ultrasonic
36. DIGITAL MULTIMETERS FLUKE 73 75 77 79 109 145 3 year warranty 0 7 0 5 and 0 3 basic dc accuracy Audible continuity 75 amp 77 Araiog dial rp Bu Fi 1987 Fluke CIRCLE 14 ON FREE INFORMATION CARD RS 422A to Loop Converter To meet increasing demand for high performance low cost RS 422 interface equipment B amp B Electronics has intro duced the new RS 422A to Current Loop Converter The Current Loop Converter is bi directional and optically isolated One channel accepts RS 422A data and output current loop the other channel accepts current loop data and outputs 422A A male DB25P connector is used for the current loop interface and a female DB25S connector is used for the RS 422A interface The unit requires 12 volts DC at about 100 mA and can be CIRCLE 59 ON FREE INFORMATION CARD purchased with an optional power supply Model 422PS which powers the RS 422A side of the isolators No further power supply is needed if the existing current loop interface is active The RS 422A to Current Loop Con verter model 422CL is priced at 44 95 Power Supply Model 422PS for the con verter is 14 95 The Loop Current Power Supply Model 422PS is 14 95 Further details may be obtained by writing or calling B amp B Electronics Manufacturing Company 1500P Boyce Memorial Drive PO Box 1008 Ottawa IL 61350 Tel 815 434 0846 Battery Back Up System Need a back up to handle both sha
37. LES aL1v201 LNIdd INIMNd INIMNd INIdd LNIdd INIMNd LNINd ILNINd ININd ILNINd LNINd ININd ININd LNINd y O10D ININd LNIdd INIWd ILNINd LNINd INIHd ININd 4 amp vPS926STP I EzId Z CT Pr I W Z 00 0 I W WuOSs r I OMWN d 334 D 0 0 O O N33H2DS AYI STD 08 KLAIM OQ O OI NO37OO 1 92 S2 W WIG dVNOV WYuSOHd SISA TIVNV XHOML3N OW dVNOV ONILSIN O99T 0S9T OST OEIT GAN OTST OOg9T O6ST EK OLST O9ST OSST OPST OEST O7SI OTST oosT O6bT O8 TI OdbT O9bT OSbT ObbT DEFI OZbT OTbT OObT OGEI OBET OLET OSET OSET OPET OCET OZET OTET OOE T 0671 oez OLZIT Os OSZT OP TI DEZI era ae OTzT 00ZzT O6TT O8TTI OLTI OSTT OSTI OPTI OETI O2TT BELL OO0TT 0601 O80T1 OLOT 0901 OSOT OPOT OtOT OZOT OTOT 0001 41 a8nd jxau uo DAnHUHOHl veaboid 37x QN3 N3HL Z W JI 099 W u t 0TOYD 1nOA L dNI OL9E I aH 000 4ON 7 u LNIMd 099 N OL I I NO4 0662 IO S A T u ININd OS9E amp LIVM 3 v31d ONILV1n21W2 LNINd 086Z weRTNOIFS i1eu3oue azzATeue O3 exTI NOX p now LNINd SID OVE SID 0462 1 O 9E BREREREEEEKEEEEEEsssxxses NOILOSS NOILYNIWITS NVYISSNYO sasuke www 0962 OZ79 OLOD NJH uw SNI JI SA3NNI SNI OZ9E OSe6z 019 OIOO NIHIL au lt gt SNI JI SASXNNI SNI OT9E OF6Z enupauoo o3 y Aue eeaid LNIMd OO9E I LX3N DES LC 314201 O6SE IA l IN N3 V O I NI N3YV O I N3 N3 M OZ6Z2 O8SE YA O IN
38. N nodes N equations must be written and solved to determine the N node voltages For our purposes all passive circuit elements i e resis tors conductors capacitors and inductors which are con nected to a given node will be assumed to have currents which run out of that node In other words the effects of those elements will appear on the left l side of Eq I Similarly independent current sources will be assumed to supply current I to both nodes to which they are con nected they supply a positive I value to the node at the point and a negative L value to the node at the tail Using that convention the effects of current sources will always be seen on the right side of Eq 1 The generalized INS of Fig 5 will help to illustrate how independent voltage sources are handled by ACNAP It is easy to see from that diagram that the voltage at the positive node of the VS is the voltage at the negative node plus the uvalue of the IVS in this case V or mathematically V V V Subtracting V from both sides we get Vi V V Eq 2 That simple equation Eq 2 can be used as a replacement for the KCL equation at node Although we have an equation for node we still must write an equation for node 2 To do that let s consider nodes and 2 to be one super node as depicted in Fig SB We can now write a standard KCL equation for that super node and use it for the equation at node 2 Voltage Controlled Curre
39. Oki instruments as well as other popular brands Price 395 Bits amp Pieces The business traveler represents an important market for all sorts of equipment and accessories Sharp Electronics Corp Sharp Plaza Mahwah NJ 07430 for example has introduced a new Travel Partner Calculator EL 470 The calculator features an alarm clock which can store time of day for two time zones an automatic Currency conversion function a calendar function and standard arithmetic operations plus percent and square root calculations The EL 470 in black comes with an attractive wallet case and the purchase price includes batteries and an instruction booklet Price 34 95 This component combo isn t likely to win any performance awards but as an example of ingenius design in the service of marketing it has definite appeal From an outfit calling itself the Electronic Sports Col lection this Electronic Cube CT V 38 features a 4 black and white TV on one face an AM FM clock radio on another and a cassette player recorder on a third surface Available from mpact 2000 60 Irons St Toms River NJ 08753 the cube is mounted on a swivel base with power supplied by an AC adapter plug Kind of an electronic entertain ment lazy susan in miniature years ago catalogs would have called it a conversation piece Price 179 95 The big news about the recently introduced Sports Watch from NDQ Marketing 989 Sixth Ave
40. Spectra is called the Onyx and in all important technical aspects and in its performance it s the same camera we tested earlier What makes the Onyx unique is its case For the first time in its history Polaroid is marketing a camera which allows users to see into the device s intri cate electronic circuitry Its see through body which Polaroid calls he cam era s unique smoked top exposes the innards of this futuristic instant camera It s striking if not spectacular Which is to say although the user can see the circuitry there isn t much action visible to the naked eye When a picture is taken a rather restrained flash of light appears briefly and faintly at one electronic juncture When we took the Onyx out of its case the exposed work ings conjured up visions of a pinball machine like process of connections being made and electrons in motion as the camera makes its 30 complex elec tronic focusing and exposure decisions within fifty thousandths of a second Unfortunately that was only a vision The reality a single flash of faint Continued on page 2 861 H38OLOO A m HANDS ON ELECTRONICS amp CO Wireless Video VIDEOSENDER Distributed by Pre mier Electronics 681 Main St Bidg 64 Belleville NJ 07109 Price 59 95 It s an old story in the world of gad getry The idea is a good one but the execution leaves a lot to be desired The example in this case is a Tai
41. TRANSISTOR printed circuit trace or poorly soldered connection may cause an imbalance in the amplifier s output at the speaker termi nal Sometimes the voltage may leak through a good tran sistor causing operating voltage to be only a few volts lower than normal Double check the wiring with the low resistance scale of the DMM Ground Connections Poor ground connections may cause dead intermittent and hum pickup noises Motorboating a rapid put put sound may result from poor ground connections in the base circuit of a driver transistor Improper voltage on the transis tors or IC terminal may be caused by faulty ground connec tions Improper ground connections in the DC amplifier cir cuits may place a high DC voltage at the speaker terminals Check the circuit for proper ground connections Most amplifiers use the chassis as common ground while others may not be grounded to the chassis Make sure all voltages are taken from a common grounded source Always replace metal shields taken from over the amplifier components Poor Tie Bars In many amplifier and TV chassis wire tie bars or short pieces of wire may connect the printed circuit wiring together from the top side of the chas sis A poorly soldered connection at either end of the wiring can result and often does in a dead Ld intermittent or distorted audio channel The improper connection of tie wires in the B voltage source feeding the various transistor
42. The Techniloop is not difficult to use and after a little practice most people become proficient at getting the most out of it Performance Most of the testing of the loop was carried out using the Sony ICF 7600D PLL Synthesized Receiver The receiver has a low impedance antenna input sock et that disables the internal ferrite rod for the BC and LF bands when in use Using that receiver the following points were noted when comparing the Techniloop 3 with the norma antenna ar rangement LF Band 153 519k Hz The loop covers that band from 200kHz upwards which is where most of the activity is in the form of RDF and weather beacons for aircraft marine and other use The Sony receiver normally uses a built in ferrite rod for this band Plugging in the loop dramatically im proved the performance and beacon sig nals which were barely discernible were brought to useful strength with a signifi cant improvement in signal to noise ratio By comparison attaching an indoor 10 meter wire antenna to the receiver on this band increased both the signal and the noise with no real improvement in read ability Broadcast Band 531 1602kHz Dur ing the day time country radio stations that were again just discernible above the noise level were brought to a useful listen ing level with the loop For country lis teners who want to listen to city stations or vice versa the loop will prove a real benefit And broadcast band D
43. Wondervision is a modular product which can include a 13 color TV with video cassette player or just the TV or just the video player The stand designed for the unit also can incorporate an AM FM radio or a remote transmitter for cordless headphones or cordless speaker Optional features are sold separately for prices ranging from 149 for the Wondervision stand to 49 for the cas sette deck remote speaker or headphones Price 499 Wondervision Entertainment System Page 10 GADGET OCTOBER 1987 Ever since the appearance of cellular car phones we ve wondered about the safety of driving and talking or driving and dialing at the same time While we don t know if highway safety was the motivation Interstate Voice Products 1849 W Sequoia Ave Orange CA 92668 has a line of cellular add ons called VocaLink a small powerful speech recognition unit for use with most cellular telephones Dialing a number with the VocaLink is not only hands free but eyes free as well Once connected to the instrument usually a simple procedure the speed recognition function is engaged by touching the keypad s pound symbol The user can dial by voice command in three different ways by speaking one of 40 programmed key words or phrases by vocally recalling a number from the car phone s memory or by simply reciting the numbers into the telephone Cellular phones with which VocaLink is compatible include General Electric and
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45. amplifier distortion without resorting to negative feedback a solution that sacrifices transient per formance The DCA 3500 also features dual power supplies The new Denon DCA 3500 is thin enough to mount out of the way To make sure heat dissipation is not a problem in close quarters the unit uses Denon s spe cial Compact Star heat sinks The design also uses efficient chimney style heat sinks with star shaped radiating fins to increase efficiency Other features include remote power on off adjustable input sensitivity and gold plated input jacks The amplifier carries a suggested retail price of 470 and For more information contact Denon America Inc 27 Law Dr Fairfield NJ 07006 Tel 201 575 7810 Jumbo LED Clock If you ve got poor eyesight or just like to say things in a big way then this may be your clock The Model 1036 Jumbo LED Clock has CIRCLE 70 ON FREE INFORMATION CARD i2 or 24 hour display capability with 6 2 25 in high red LED digits The battery backed up quartz crystal time base auto matically takes over during power failures when the clock operates from a 60 Hz power line The clock will also operate from 12 VDC The high tech black plex iglas enclosure is attractive and func tional great for ham shack computer room radio station communications center home office and more The di mensions are 15 25 x 4 75 x 1 5 inches with a viewing distance of over 100 feet The mod
46. an ohms capacitance and fre quency meter Detailed instructions 2 50 BAG NALL ELECTRONICS 179 May Fairfield CT 06430 STRANGE stuff Plans kits items Build satellite dish 69 00 Descramblers bugs adult toys Infor mational photo package 3 00 refundable DIRIJO CORPORATION Box 212 H Lowell NC 28098 CATALOG Hobby circuits licensed unlicensed E transmitters antennas books scramblers bugging devices science projects more PANAXIS Box 130 HO 10 Paradise CA 95967 DETECTIVE Equipment micro voice transmitter UHF band highly sensitive and tuneable Will fit inside an aspirin box including battery 1 inch anten na Micro telephone transmitter FM VHF band tuneable Powerful clip on type All parts available at local Radio Shack store Detail plans 10 00 ea or 15 00 for both when purchased together Free catalog listing many other devices of this nature with order Catalog only 5 00 refundable WILSON P O Box 5264 Augusta GA 30906 VOICE disguisers FM bugs Telephone transmit ters Phone snoops More Catalog 1 00 refunda ble XANDI ELECTRONICS Box 25647 32F Tempe AZ 85282 PROJECTION TV Convert Wed TV to project 7 foot picture Results comparable to 2 500 00 proj ectors Total cost less than 30 00 Plans and 8 lens 21 95 Illustrated information free MAC ROCOMA HB Washington Crossing PA 18977 Creditcard orders 24 Hours 215 736 3979 AMPLIFIER plans Total
47. any number of stereo configurations should have more versatility in the cable couplings and they should be supplied not option al Other Partner optional accessories include a clamp system a Jo Bose Roommates Partners are in fact a response tothe phenomenal success of the Roommate series But as we ve come to expect from AR the company doesn t do anything unless they are going to do it well Part ners come out at the top end of the per sonal stereo spectrum providing a clean compatible adjunct to your Walkman your car stereo or your home video sys tem G R OCTOBER 1987 Superiorit y Complex PROTON 625 MONITOR RECEIV ER Manufactured by Proton Corp 737 W Artesia Blvd Compton CA 90220 Price 1 099 PROTON 313 LOUDSPEAKERS Manufactured by Proton Corp Price per pair 300 Recent print advertisements for Proton audio video equipment were headed When you arrive Proton As an ex ercise in electronic age snob appeal the phrase when you arrive makes it clear that this 25 monitor receiver is pitched as an accoutrement of life at the top For those of us who don t know if we re going anywhere let alone if we ve arrived the slogan doesn t really say much Monitor receiver is also an important snob appeal buzz term It s used by manufacturers and marketeers so that a low brow term like television set won t demean their high tech consume
48. as a haven for freed slaves Untortunately Liberia never lived up to the dreams of its idealistic founders It is today just another poor and undeveloped Third World country steaming away in one of the hottest and most humid corners of Africa America though is still offering as sistance to the tiny African country which was once its ward One way is the USAID sponsored Liberian Rural Communica rions Network which set up a series of broadcasting stations last year to bring local radio to the feast developed parts of the country Those local stations in places with names like Voinjama Zwedru and Gbarnga are low powered medium wave outlets normally not audible much beyc nd their 75 mile primary range But they are served by a LRCN shortwave link which can be received by SWL s in North America There are three other shortwave ser vices in Liberia for the shortwave listener to track down and log One is the easy to hear but not very exciting Voice of America VOA relay station at the Liber ian capital of Monrovia Tougher and therefore more challeng ing DX targets are two other shortwave services the commercial Liberian Broad casting System and the cultural and re ligious broadcasting service of the Sudan Interior Mission Radio ELWA LRCN is the newest of the lot and the most recent to come to the attention of North American SWL s It operates a 10 kilowatt independent sideband transmit
49. as a radio operator with the Marines He d been an SWL since the age of 12 or so and had done his listening on home made re ceivers Just before the war Dan bought himself and EC which he used until he was about to be sent overseas The he shipped it home to his dad and bought himself a Hallicrafters S29 battery oper ated portable set The Hallicrafters worked for about a year until mold and rust eventually put it out of action Unlike George Dan must have made it to the Pacific The Echo phone however performed beautifully for Dan s dad al during the war With his letter Dan enclosed a Xerox of the origi nal Echophone instruction manual Need less to say was delighted to receive that bit of information and will be sharing some of its contents with you soon My own Echophone shows some inter esting internal evidence of having gone through World War II but UI need some help from a knowledgeable reader to un cover the whole story While working un der the chassis I noticed that a wire toone of the oscillator s trimmer capacitors had been disconnected effectively putting the set out of operation on its highest frequency range 8 30 MHz That was obviously neither an accident nor a case of mindless butchery the wire had been men E c gt d Aa D I neatly and deliberately cut and removed vc heard that during the war radio service technicians were instructed by the government to disab
50. between the two speakers There is a balance control and the built in graphic equalizer allows the indi vidual to boost or attenuate the response of five separate frequencies The RX FD80 operates on 10 D bat teries not included Jacks are provided for AC in headphones line in 2 line out 2 and mixing microphone The unit is currently available at a sug gested retail price of 339 95 For more Continued on page 100 TOLL FREE ORDERS Se e Bi Complete functioning assembly includes ballast g on off switch power cord sockets and F4T5 BL blacklight Mounted on a 7 1 8 X 3 1 8 metal plate Use for special effects lighting or erasing EPROMS CAT BLTA 10 00 EACH 1 mA METER P Modutec 0 1 mA signal strength meter with KLM logo 1 4 X 1 3 4 x 7 8 deep CAT MET 2 2 00 each PUSHBUTTON PHONE t Spectra phone Model OP 1 piece telephone with rotary pulse output Operates on most rotary or touch tone systems Features h last minute redial and mute button Includes coil cord with standard modular plug IVORY CAT PHN 1 8 50 EACH 2 FOR 15 00 SWITCHING POWER SUPPLY Compact well regulated switching power supply designed to power Texas Instruments computer equipment INPUT 14 25 vac 8 1 amp OUTPUT 12 vdc 8 350 ma 5 vdc 8 1 2 amp 5 vdc 8 200 ma SIZE 4 3 4 square Includes 18 Vac 8 1 amp wall transformer designed to power this supply CAT PS TX 5 00 SET
51. book What particularly like about it is that it can be connected to the telephone lines just about anyplace even down in the base ment where my workshop is located says John Peabody of Macon GA Take a look at Fig 4 You ll notice that no external power source is needed the phone company takes care of that The tape recorder s switch terminals are ap plied to a pair of transistors connected as Darlingtons that are used to turn the re corder on and off All you need is a nega tive voltage at the base of QI to stop the recorder usually about 50 volts DC across the phone that s divided over RI R2 and R4 so that QI s base is negative enough to keep the recorder off Pick up the receiver voltage drops to 5 volts That leaves not quite enough voltage on QI s base to keep that transistor at cutoff so the recorder begins Nice huh Just remember to keep your recorder s switch in the oN position and depending on how many people use the telephone remember to rewind or change tapes occasionally And one more thing to remember John Remember to watch the mails for your copy of the Fips book Light Flasher My friends and l are all electronics hob byists and we re constantly testing each other just for fun One of the guys built an R C circuit using an NE 2 neon lamp a big battery a resistor and a capacitor The neon lamp blinks happily away on and R6 d 2 7K 2N2222 Fig 3 The op amp out
52. cant rsonalized training You learn best with flexible training so we let you choose from a broad range of courses You start with what you know a little or a lot and you go wherever you want as far as you want With CIE you Cleveland Institute of Electronics 1776 East 17th St Cleveland Ohio 44114 YES I wantto get started Send me my CIE schoo catalog including details about the Associate Degree Program I am most interested in O computer repair O television high fidelity service Jtelecommunications O medical electronics O robotics automation O broadcast engineering Ci other Address J Apt City State Zip Age Area Code Phone No Check box for G I Bulletin on Educational Benefits O Active Duty MAIL TODAY OD Veteran Print Name CIRCLE 6 ON FREE INFORMATION CARD 2861 H380J120 E FRIEDMAN ow ewen mm By Herb Friedman How to stretch your budget for hard disk storage JAS PROGRAMS CONTINUE GETTING larger and more complex the standard two floppy configuration of IBM com patible computers is hard pressed to provide the necessary storage Soon the average user starts to think in terms of the megabyte storage capacity of a hard disk system Although the past year has seen the price of a hard disk unit drop like a lump of lead even the most minimal priced from 85 to about 100 The con troller usually comes with a set of two cables that connect the
53. charge while the formerly neutral atoms they were removed from are now positive ions In the ionosphere the air density ts so low that electrons can travel relatively long distances richocheting off one an other in a domino affect before recom bining with oppositely charged ions to form electrically neutral atoms As a re sult the ionosphere remains ionized for long periods of the day even after sun set At lower altitudes however air density is greater and recombination therefore occurs rapidly At those altitudes solar ionization diminishes to nearly zero im mediately after sunset or never achieves any significant levels even at noon lonospheric propagation is seen in the form of a sky wave which is responsi ble for the so called skip phenomena seen in the MW HF and lower VHF trequency regions It is skip that makes those signals propagate over long even intercontinen tal distances Well that s about all the space we have for this month But be with us next time when we ll continue our discussion of ra dio propagation with a closer look at ground wave communications taking a closer look at tropospheric propagation and then continuing with a look at sKip the DX ers delight So until then if you have any questions comments or sug gestions write to Joe Carr K4IPV PO atmosphere that is above the stratosphere Box 1099 Falls Church VA 22041 E TROPOSPHERIC PATH p M oH D ee es Le et Bee
54. circuitry to boost its price to a non an AC adapter with which to plug the were willing to write off to Manhat competitive retail level And while the device into a wall outlet tan s enormously crowded ether cables and lines of the VCR Rabbit or In operation the Videosender is A second test conducted in an edi the Multiplier can be unsightly they re placed on top of the VCR originating tor s suburban home had a different not half the distraction represented programming with the device s anten outcome The Videosender transmitted by red horizontal interference lines na extended The receiving TV must be a VCR program to a second TV in the across the transmitted image We give equipped with a UHF loop style anten home It required some fine tuning and the manufacturers of the Videosender na A closer look at the enclosed in a little exploration of the UHF band to a B plus for conception and a D minus structions amends the original claim discover which channel was the best in execution G A SPECTRA ONYX duced the visible Onyx awards are passed out we d be surprised Cont from p I Our cynical nature suggests that the if the Onyx doesn t manage to snag one Onyx isn t so much a gesture towards for Polaroid as well it should G A strength is nowhere near our imagin design as an attempt to pep up market ings But this development is still signi ing of the Spectra System Polaroid in CORRECTION f
55. controller to the drive Depending on the particular dealer you might have to do some fast talking to get the cables thrown in but if he won t do it try a different dealer or make the cables yourself the connectors are standard While there are other kinds of controllers in the marketplace some of which such as the RLL type claim to provide greater disk storage capacity compared to the the Western Digital controller tf you want to have the system work the first time or with a minimum number of headaches stick with the WX and WX 2 controllers Enough Power If you have one ot the older computers with a 60 watt power supply and full size hard disk system comes out to several hundred dollars But there s a lot of inexpensive hard disk hardware floating around the surplus and mail order dealers not to overlook the flea markets Even without a cal culator it s easy enough to figure out that a hard disk system won t cost much beyond 225 if you do it vourself Untor tunately doing it yourself can turn out to be prohibitively expensive if you don t know what you re doing and very few dealers at least in our experience will give you much assistance In fact some won t give any assistance What vou order is what vou get LLL First things first why are some hard disk drives so cheap It s hecause the husiness market for whom they re in tended want Capacities
56. electronics hobbyists seldom think of it the op amp is quite at home in power supply circuits It is truly a general purpose device E Does fighting the crowds at Christmas short circuit your holiday fun Don t blow a fuse this year for the friend who shares your love of project oriented electronics or a youngster who may need only a spark to ignite a life long interest give a gift subscription to Hands On Electronics Because when you give him Hands On Electronics you re giving him valuable Hands On experience month after month of challenging construction projects including complete plans for testing equipment electronic worksavers for home and car add ons and modifications for hi fi computers radio and TV He ll get all the how to he needs to build exciting useful projects like these a touch light dimmer a traveler s theft alarm an economy NiCd battery charger a voice synthesizer a wave form generator the ultimate burglar alarm a stereo graphic equalizer and many many more PLUS testbench tips and techniques circuit design electronics fundamentals book reviews and new product news including our new 12 page Gadget section regular columns on computers scanners dx ing ham and antique radio the list goes on and on Give a Friend A Hands Ou Experience for Christmas SAVE MONEY great gift to receive Hands On E
57. equal to the ferrite rod s length Thus an average ferrite rod of say 150 mm length will provide about the same signal ta the receiver as a loop antenna with a diameter around 150 mm Given that loop antenna signal pickup is proportional to the square of the diameter it is easy to see that it does not take a giant loop to outperform even the very largest available ferrite rod Added to this the loop has better efficiency at higher frequencies than the standard ferrite rod which exhibits increasing losses above 2 to 3 MHz The loop antenna is usually tuned by a variable capacitor and its output coupled directly or inductively by a second small winding into the receiver input This article originally appeared in Electronics Australia in December of 1986 it has been updated to include changes in pricing of the kits ACTIVE ANTENNA FOR BETTER DX ING The main advantage of a loop antenna over the traditional long wire is a marked reduction in noise pickup That reduc tion is due to the fact that a loop can be tuned Also it is directional and smaller in size A long wire may pick up more signal but readability may be worse especially on weak signals due to broadband noise An improvement in signal noise ratio is the loop s greatest benefit along with greater selectivity due to the fact that the loop is tuned to the frequency being received Fig 1 The conventiona loo antenna was large and unsightly
58. foil pattern is given in Fig 3 Once you have a circuit board the first job is to fit the components to the printed circuit board as shown in Fig 4 Fit the components to the top side of the board first That done fasten the connectors with the screws provided and insert the Switches making sure that they are pushed right in before soldering The tuning capacitor and output level potentiometer are installed on the track side Bend the potentiometer lugs 90 towards the shaft before installing it on the board The tuning capacitor should be secured using the two screws supplied The coax output socket is installed directly on the PCB Locate the central lug squarely over its PCB track and solder it to the board along with the two small outer tags Next anchor the 9 volt battery snap leads through the hole provided near the edge ot the board and solder them to their respective pads red to positive That done fit the plugpack wires and solder them to the 3 5 mm socket provided red to the tip Fig 3 The circuit trace pattern shown here is the same size as the circuit board so you can use this to make your own printed circuit board using the positive resist method 2861 H38O0120 m m ML TI B S02 eevee eon eeeeeeeen es S L eeeeeeee TO POWER PACK HANDS ON ELECTRONICS zl CO Fig 4 Please take note that in this layout for the PCB the tuning capacitor and potentiometer are mounted on
59. graphics programming on the IBM PC Advanced Graphics in C offers a spe cial graphics program called GRAPHIQ that provides a complete toolkit of all the routines you Ill need for graphics opera tions Johnson shows you how to use GRAPHIQ to implement or adapt graph ics in your C programs It also provides A special appendix that includes the code for GRAPHIQ a complete graphics program with a rotata ble and scalable character set Its full of DI 2 f 71 x a i Graphics in C o ch 18 L XA E da IA Et l eim oe CIRCLE 55 ON FREE INFORMATION CARD tools not available elsewhere An entire stroke front character set code for the AT amp T Image Capture Board information on serial and parallel interfacing to mice light pens and digitizers With this text you ll learn state of the art techniques from Johnson so that you can easily create the graphics you need The book contains 660 pages and re tails for 22 95 from Osborne McGraw Hill 2600 lOth Street Berkeley CA 94701 Tel 415 548 2805 Your Best Interest A Money Book for the Computer Age By Tom Weishaar We are peasants in the Dark Ages of money Compound interest confounds us Interest rate magicians pick our pockets daily monthly and quarterly But just as the printing press liberated us from feudalism and superstition the personal computer can now free us from the decep tion of financial warlocks Until now there have been bo
60. is an eastern European broad caster widely heard in North America Its Sunday Magazine program in English has been logged here at 0100 and also at 0300 Try also 7 345 and 11 990 kHz French Guiana 3 385 FR3 is the SW voice of this colonial French outpost in South America which has been noted at about 0930 hours with a program schedule a rooster s crowing and then popular music Falkland Istands 3 958 from the South Atlantic comes the programming of the British Forces Broadcasting Service aired by the Falkland Islands Broadcast ing Station Try this one around 0800 to 0900 Greenland 3 999 Gronlands Radio is reported as heard with Danish program ming an interval signal and choral music from just before 1000 hours Guatemala 4 825 Radio Mam is a Spanish language shortwave outlet that can be heard around 1230 with lively Lat in vocals Monaco 7 105 Trans World Radio opens in English at 0720 sign on with a music box tuning signal and indentifica tion announcements then on to religious programming Tunisia 12 005 Radio Tunis is found here just above the 12 000 kHz mark with Arabic music and announcements at 1900 hours CREDITS Pete Tutak WA Kirk Allen OK Norman Bobb MN Robert Tomko NJ Rufus Jordan PA Scott Nelson ND Paul Brouillette IL Brian Alexander Richard D Angelo Peter Dillon MD Daniel Sampson WI North American Shortwave Association 45 Wildflower Road Levittown PA 19059
61. like a GE 47 through a half inch rubber grom met atop the box See Fig 5 When you press switch Sl a momentary contact push to make switch the capacitor takes a rapid charge to 7 volts The transistor is forward biased al lowing collector current to flow and oper ate the relay which has a 200 ohm coil When you release switch S1 the capacitor discharges through the 33 000 ohm re sistor and when the capacitor voltage is down to about half a volt the transistor base is no longer forward biased and the transistor stops conducting As a result the relay opens All you ve got to do is wire the contacts of the relay to the small pilot lamp and put the battery contacts in series with them The other pair of relay contacts are wired so the normally open contacts are con nected in parallel with switch SI Sounds like a lot of fun Fred Fm sure you ve driven them nuts And talking about fun wait till your friends get a look at the Fips book that s on the way to you Code Practice Oscillator Byron know ve seen schematics for code practice oscillators in the past but now need one in a hurry as I m going to be teaching an amateur radio class in my local adult education system Got any thing L B Kansas City KS The circuit shown in Fig 6 should end your quest But before we get into the details understand that if you replace the telegraph key with an ordinary switch you ve also got a signaling device It also
62. makes a great electronic doorbell Re place the telegraph key with pair of test leads and you ve got an audible con tinuity checker The audio tone is generated by a relaxa tion oscillator built around a 2N4871 UJT operating at a frequency of I SKHz If you want a lower tone simply increase the value of capacitor Cl The sawtooth waveform generated across Cl is coupled through C2 and R4 to the base of Q2 a simple common emitter class A output amplifier Resistor R4 assures that the out put stage doesn t overload the oscillator Capacitor C3 roils off the output stage s high frequency response reduces the har monic content and provides a more pure and pleasing sound that won t tire you after listening for long periods of time 01 R2 2N2926 33K d C1 de 100 HI 47K 1 Auto Advance Projector I m into photography And when I do a slide show Id like the slides to change automatically instead of having to push the remote button for each new slide Got any ideas Byron P G Neenah WI Sure thing P G Check out Fig 7 That circuit built around a 4001 quad two input NOR gate even provides switch se lectable auto advance times of 5 10 15 20 25 or 30 seconds through the remote R3 1 5 MEG R2 C1 1 5 MEG 1 4 4001 1 4 4001 control socket of your projector Three of 6V CDIL 1 4 4001 Fig 6 The audio output of the code practice os
63. mental tool The book is 406 pages and retails for 16 95 from Que Corporation 7999 Knue Road Suite 202 Indianapolis IN 46250 Tel 317 842 7162 Advanced C Techniques and Applications By Gerald E Sobelman and David E Krekelberg If you have basic knowledge of the C programming language and are ready for more then you should have Advanced C Techniques and Applications By the time you finish Advanced C you will have constructed several state of the CIRCLE 58 ON FREE INFORMATION CARD art applications Learn how to generate and control advanced graphics develop a menu driven multiwindow environment and construct advanced user interfaces Advanced C is one of the few books available that focuses on the advanced fea tures and capabilities of the C program ming language Important topics in this book include C coding style pointers re cursion structures linked lists and trees The book can give you a deeper under standing of the C language and help you develop techniques that will enhance your programming skills The book containing 316 pages retails for 21 95 from Que Corporation 7999 Knue Road Suite 202 Indianapolis IN 46250 Tel 317 842 7162 E LI LLL RTE CIE MAKES THE WORLD can even earn your Associate in Applied Science Degree in Elec tronics Engineering Technology Of course you set your own pace and if you ever have questions or problems our instructors are only a t
64. my Echophone restoration project But here s a little bit of background infor mation for the newcomers In the July column announced that we d occasion ally feature a set for restoration in is On Antique Radio For the first candidate selected an Echophone ECI which I d recently picked up at a hamfest Built in the early 1940 s the little Echophone was designed for shortwave listeners with lim ited budgets It s a set with a great deal of charm and its sturdy construction and good looks belie its low original selling price about 25 00 As received it the set was relatively intact and in good cosmetic condition except for several layers of encrusted grime especially on the chassis top It was so dirty that decided to do some deep cleaning even before trying it out Last month reported on the dismantling and cleaning process as started to work on the set This month only the main tuning bandspread capacitor already removed from the chassis remained to be cleaned Reassembling the Set After some thought decided that the best way to get the dust and dirt out of the capacitor would be a good soaking in min eral spirits followed by compressed air blow dry That worked quite well but be fore could reinstall the unit had to solve another small problem The capaci tor s mounting screws had passed through soft rubber vibration absorbing grommets installed in the chassis Those were hard
65. of the schematic Since both left and right channels are identical the normal channel voltages and components may be compared with the defec tive audio channel Improper voltages may cause distortion weak or dead conditions in the amplifier circuits R1 22022 LEFT CHANNEL Fig 3 High B positive and negative volt SPKR ages are found in high powered amplifiers Three or four voltage levels may be fed FROM to high powered amplifier circuits Q7 AND 03 Accurate resistance measurements of bias and emitter re sistors may help to locate a dead weak or distorted stage When making such measurements it s best to remove one end of a suspected resistor In that way other components within that stage will not distort the reading For instance there may be another resistor series connected in the collec tor of the transistor which would drive the meter reading TRANSISTOR IC power far above the actual value of the resistance being measured DRIVER SECTION AMPLIFIER Resistance measurements from each transistor or b n r e ER di IC terminal to common ground may help to locate g vi r re p the defective stage Always compare each resis We i i X T i E Ve a Transistors may be checked in seconds with the diode transistor test of the DMM During replacement put silicone grease on the tabs of transistors or IC s HEATSINK 2861 H38O0100 HANDS ON ELECTRONICS e SLYVANIA MODEL R73 3 OPEN CAPACITOR
66. ot sight so to speak of your antenna For the record the channel used to send com mands to satellite ts 154 20 MHz Getting back down to earth most scan ner owners are not aware of the General Mobile Radio Service GMRS band hat s a sort of cousin to the 27 MHz CB band although you won t hear the kids and truckers there In many areas however you will hear REACT teams and any hobbyists on those frequencies in addition to business users For the most part repeaters are the way to go in GMRS Repeater frequencies are 462 55 462 575 462 60 462 625 462 65 462 675 462 70 and 462 725 MHz The repeaters are paired with input frequen cies exactly 5 MHz higher 467 55 467 575 etc You ll be primarily inter ested in what s taking place on the 462 MHz channels E J Coop Cooper of Silver Springs dard VHF low and high bands plus the nels per second speed A weather key in UHF and UHF T bands you can access stantly tunes the unit to the nearest active four amateur radio bands 114 2 6 and 10 162 MHz NOAA weather channel just meters the 136 to 144 MHz space re push a button and you re there search band the 118 to 136 MHz VHF The Regency Electronics Turbo Scan aero band the federal agency band at 406 800 also has the standard scanner tea to 420 MHz and the controversial 800 tures scan delay channel lockouts direct MHz band actually 806 through 950 channel access as well as two tele
67. output of an integrator can t reach infinity no matter how long the input signal is left on The output is limited by the negative A and positive B power supply values A perpetual motion machine it s not others it is undesirable A switching transistor is connected across the capacitor to discharge it in some applications The output voltage V at any given time is dependent upon the resistor R and capacitor C values the input voltage V and the time t allowed for integration All that is summed up in the expression Vo NOUR In Step 8 you let the circuit integrate for 5 seconds The output voltage at that time assuming a 9 volt input should have been Vo 9 1 10 000 x 000001 5 Vo 9X 15 4 5 volts Because of inaccuracies in your timing component val ues or Measurement errors your value may be different but it should be close Moving On 9 Construct the circuit shown in Fig 13 using the second op amp in the 1458 IC Note that the two 10 000 ohm re sistors form a voltage divider to furnish half the supply voltage to the or reference input at pin 5 The 10 000 ohm potentiometer is connected as a variable voltage divider to supply the other input at pin 6 10 Apply power to the circuit Use your VOM to measure the voltage between pin 6 and ground Adjust the potentiome ter for zero volts 11 Connect your VOM between the op amp output at pin 7 and ground Note the output voltage Vo
68. products or services 1 40 per word prepaid no charge for ZIP code MINIMUM 15 WORDS 5 discount for same ad in 6 issues within one year 10 discount for 12 issues within one year if prepaid NON COMMERCIAL RATE for individuals who want to buy or sell a personal item 1 15 per word prepaid no minimum ONLY FIRST WORD AND NAME set in bold caps at no extra charge Additional bold face not available as all caps 25 per word additional 20 premium Entire ad in boldface add 20 premium to total price TINT SCREEN BEHIND ENTIRE AD add 25 premium to total price TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD add 45 premium to total price EXPANDED TYPE AD 1 85 per word prepaid All other items same as for STANDARD COMMERCIAL RATE TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD add 25 premium to total price TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD PLUS ALL BOLD FACE AD add 45 premium to total price DISPLAY ADS 1 x 2w 160 00 2 x 214 320 00 3 x 2 4 480 00 General Information Frequency rates and prepayment discounts are available ALL COPY SUBJECT TO PUBLISHERS APPROVAL ADVERTISEMENTS USING P O BOX ADDRESS WILL NOT BE ACCEPTED UNTIL ADVERTISER SUPPLIES PUBLISHER WITH PERMANENT ADDRESS AND PHONE NUMBER Hands on Electronics is published monthly therefore copy to be in our hands for Nov 87 7 20 Dec 87 8 19 Jan 88 9 18 PLANS KITS BUILD this five digit panel meter and square wave generator including
69. regenerating and volume controls Drill out the 86i HSEOLDO eo gt HANDS ON ELECTRONICS Lal ho perfboard so both controls will fit flush with the top panel Reter to the photos and Fig 3 The shaft mounting nuts on the two controls will hold the PC pertboard to the front panel Wiring Up the Radio The mounting and wiring of the various small components is not critical provided you follow the author s layout some what Refer to the author s unit shown in the photos Place the DIP socket between the volume and regeneration control Transistor Ql is mounted to the left close to the antenna and ground posts Transistor Q2 is mounted next to the outside near the tuning capacitor All other small parts may be mounted as they are wired into the circuit From pin 4 of the UI socket run a length of bare wire up the row of soldering holes for easy ground connections Like wise run a bare piece of hookup wire from pin 6 of the DIP socket down the soldered holes tor the B connections Be careful when soldering up the DIP terminals so that excess solder does not establish a shorting solder bridge Remove the excess solder with a piece of solder wick mesh material Use a pocket knite blade between the two rows of terminals to clean out sol der from the adjacent terminal as the solder is heated Keep the soldered con nection close to the perfboard so the board fits tightly against the front panel Solder up two 3 inch piece
70. simply installing two LED s on one of the plastic filler panels or cut a front panel from a piece of plastic Use a small wire tie indicated by the pointer to keep the wires together Setting the DIP s The drive comes with a data sheet that tells how to set the internal DIP switches for one or two drives If you didn t get the data sheet get on the phone and insist that they send the data or give you the information over the phone Set the DIP switches accordingly and install the drive in the computer Attach the LED connector and then seat or tape the front panel onto the cabinet Install the two connecting ribbon cables between the controller and the disk drive The color coded wire on one side of each cable is pin for that cable Next program the controller for the disk drive Programming is done by simply moving a few jumper blocks to the appropriate pin connections as the photos show For clarity we have tem porarily removed the cables How do you know what goes where The controller should have been supplied with a small paper guide that shows which block goes where depending on factors such as whether the drive is 10 or 20 megabytes the sector arrangement etc Continued on page 100 f K nos o PTT CAMERA 7 AB DATE 7004 TAKE ONE Take one look at the new MCM catalog and you ll discover e An unbeatable line up of parts and products e Many new items that are hard to find G
71. slide switch 52 2 pole 3 position slide switch Printed circuit board plastic case 50 90 x 150mmor similar Sato 10 turn vernier dial knob for tuner right angle bracket with hardware two 9 volt battery con nectors 380 mm loop forming plastic strip 16 conduc tor ribbon cable 3 meters piece of foam to insulate battery jumper wire solder etc A tull kit of parts order TL3 S for the project is available from Technikit Electronics 55 Webber Pde East Keilor Victoria 3033 Australia It comes complete with a pre punched case a screen printed front panel and a single set of loop coil components with sufficient cable tor either a one or two layer coil The price for the kit is 69 ppd Payment may be made by international money order bank draft or Mastercard Coil Construction Begin by shaping the former strip supplied into a circle To do that over lap the ends by exactly 20 mm mark first with a pencil and then bind the ends with two or three layers of plastic tape Next fold one end of the cable at 90 see photograph leaving at least a 50 mm lead out Tape that end to the former next to the fold so that the inner edge of the lead out runs along the line of one of the overlapped former ends Now rotate the former by hand while feeding the cable centrally on to it until you have the number of layers required That done fold the end of the cable in the same way as the start Note that the inner edge of th
72. source voltage source etc a sinewave reference and polar coordi nates must be used That is they must be in the form 12 56 SIN wt 26 78 5 No two voltage sources IVS may be connected to the same node not Counting the ground node Node 0 Press any key The first two rules state that each circuit node must be given an integer reference number and that the ground node must be node 0 You don t need to number the nodes in any particular order but you must make certain that no integer is skipped If a number is skipped for example if there is a node 5 and a node 7 but no node 6 then the error message of line 3110 will be displayed The next rule states that the ground node node 0 is not counted when determining the number of nodes in a circuit Again if that rule is not followed the error message of line 3110 will appear One of the most important rules is Rule 4 which states that power supply elements must be entered in polar coordi nates with a sinewave reference If the circuit you wish to analyze has active components based on a cosinewave you must convert it 10 a sinewave by adding 90 degrees to its phase angle For an angle of 0 degrees the following can be written COS 0 SIN 0 90 Another important point should be brought out based on the equation for the sinewave given in Rule 4 Note that the wt term has units of radians resulting from radians per 406 U383O0100 amp Lal HAN
73. speaker The small radio circuit powered by a 9 volt tran sistor battery has a current drain of 10 7 milliamperes Most small battery operated radios have an operating current drain of 8 5 20 milliamperes Winding the Coils First start winding L2 in the center of a AM band ferrite rod with number 24 enameled wire Refer to Fig 2 Place a small piece of masking tape under the starting wire to hold it in place Wind on approximately 73 turns and place a piece of masking tape over the winding while twisting the wire several times to make the tap connections Now wind on another six turns A 3 inch rod should be able to hold those turns however you will find a slightly longer rod easier to work with At the end of L2 place a layer of masking tape to keep the coil from unwinding Clean off the enamel at the tap and solder a four inch piece of hookup wire to the tap In the middle of L2 place a layer of masking tape Wind 32 turns of number 28 enameled wire over the masking tape for the primary winding Ll Secure both ends of the winding with masking tape Both coils are close wound CW and wound in the same direction Leave four inch connecting wires at each end of the coils The PC Board A pre drilled IC LS1 perfboard was used as the PC board for mounting parts for Grandpa s Antique Radio Of course a regular perfboard will do Here a predrilled 2 7ie X 3 inch perfboard was prepared by drilling two 12 inch holes to mount the
74. sponge Water is intro duced via pin holes bored in the side of the plastic watch casing Beyong its ec centric power source the Water Watch is a fairly basic digital timepiece capa ble of displaying time day date and seconds We had our problems with both the Water Watch and the virtually identical if more imaginatively packaged and marketed H O Watch Water water everywhere but how do you get it into the watch We spent an afternoon holding these wristwatches under faucets pouring water over them and finally dunking them into cups of water The directions airily spoke of running cold tap water over the watch for two seconds or placing it in a glass of water for a few minutes We thought trying to fill these instruments with water was more like feeding fledglings with an eye dropper A darkening of the sponge signaled that the water was absorbed but with each of the watches there seemed al ways to be one strip of sponge deter mined to stay dry The case of one of VentuResearch s models wasn t trans parent so there was no way to judge absorption Each of the watches was supposed to signal its activation by flashing a par ticular set of numerals on its display When you activate your watch the display will show 1 00 with a flashing colon The H O Watch instructions proudly proclaimed it a five function quartz solid state timepiece Unfortunately this meant that when activate
75. the reverse copper side of the board C4 The dial can now be fastened to the panel with the screws provided Set the dial to read zero then rotate the tuning capacitor shaft to the fully counterclockwise position The front panel can then be secured to the band switch by means of two selt tapping screws Check that the PCB and panel are parallel to each other before tightening the dial fastening Screws Finally fit the output knob and clip on the battery Wrap the battery in foam betore installing the assembly in the case The Loop Coils The basic kit contains one coil former strip two cable connectors and sufficient wire for a one or two layer loop based on a 300 mm diameter coil A one layer 300 mm loop will tune trom IMHz to 13 5MHz while a two layer loop will tune from SOOKHz to SMHz It you want to go lower down extra cable tormers and connectors are available A five layer loop tor example will tune from 200KHz to 2MHz From that you can see that two coils one of five layers and one of one layer will cover 200kHz to 13 5MHz with a good degree of overlap between coils It your main interest is say broadcast band DX and or the ee T O a As you can see the tuning capacitor and potentiometer are mounted on the foil side of the board Note also how the contact strips on the coaxial connector hold it in place 80 meter amateur band then a two layer loop will probably be all you ll need The one
76. voltage of the diac around 30 to 40 volts the diac conducts dumping C1 s charge across the gate of the triac triggering it into conduction Note that although a separate triac and diac are shown the author used a quadrac a combination of the two contained in a single TO 220 package in the prototype One Step Beyond The basic circuit of Fig 1 can be upgraded as shown in Fig 2 by the addition of a 3 position center off switch and neon lamp with self contained resistor Those few compo nents make the circuit more flexible and useful In order to get some light indication in the lower scale of the regulation a neon lamp NEI an NE2H from Radio Shack which has higher power capacity has been used The addition of the switch proved to be very useful since the operation of the station became much easier Once you find a proper place for the temperature mainte nance of the iron you can switch S2 to the thru position without moving the setting of RI Then when you don t need the iron for a few minutes you may switch S2 to the in position Depending on your needs and the position of RI you can switch S2 to the thru position or leave it in the in position For those that would like to roll their own instead of buying it ready made the values of the components are given in the Parts List Generally the triac has to have about twice the current handling capability of the highest wattage iron that will be connected to the proje
77. way up to tomorrow s Scale Integrated circuitry In your very first module you ll Perform _ Ak Q latest VLSI Very Large wem temporary circuits a who finds electronics playing an increasingly important role in your work It s even for electronics engineers or technicians who feel their training needs freshening up It s the quickest most convenient probably least ou do it And the P j only one that gives ia you hands on experience wes 2 Ge 4 15 Day No Risk Trial To order your first module without risk send the card today use integrated circuits to build adigital Examine it for 15 days under the oscillator verifying its operation with a light emitting diode LED You ll learn to identify passive and active components understand concepts common to all electronic circuits For Anyone Interested in Electronics The Contemporary Electronics Series is designed for anyone from hobbyist to professional It s for you if you re looking for new fields of interest if you re a teacher who terms of the order form and see how the Contemporary Electronics Series gets you into today s electronics If card has been used write us for ordering information A M Hill McGraw Hill Continuing Education Center 3939 Wisconsin Ave Washington D C 20016 EN e wants an update in con manager or supervisor in an electronics plant a doctor an e
78. when excessive hum is present in both speak ers A real loud or floating buzz may be caused by a dried out filter or decou pling capacitor in the low voltage pow Bare tie bar wires may be used on the top of the circuit board to hold the wires together Inspect and solder tie wires when intermittent and or DC circuits are encountered Fig 4 Excessive hum may be caused by large filter or decoupling capacitors within the low voltage power supply that may have opened up or deteriorated Hum and distortion may result from leaky output transistors or IC components er supply circuit see Fig 4 Test for leaky transistors or IC components and open or burned output bias resistors when hum and distortion are found in one speaker Shunt each filter capacitor with the same capacity and voltage with clip wires and the power turned off Although most high powered amplifiers have a separate power IC in each channel suspect a leaky common power IC when both speakers contain hum and distortion Hum may be caused in one stereo channel by an oxidized variable bias resistor Slightly rotate the bias resistor and notice if the hum disappears Spray the resistor with cleaning fluid and return it to it s original position Use the other channel for comparison tests when either the right or left channel is dead weak or distorted The dead channel is much easier to locate than a weak stereo channel Quickly test each transistor and IC N
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80. 01 units aren t Hence the warning 301 powered speakers should be at least one foot away A further audio caution in the manual sounds more serious If unshielded speakers are too close to the 625 you will see color smearing or purple blotches In these circumstances Proton warns immediately move the speakers away from the 625 and turn the receiver off After ten minutes turn it on again Repeat as necessary Likewise placing a VCR too close to the 625 can interfere with this audio video powerhouse s performance An entry in the manual s trouble shooting section adds the snobbish Continued on page 9 GADGET Page 5 861 H380120 o HANDS ON ELECTRONICS go RO Chicago Show Down The hardware at this year s summer Consumer Electronics Show in Chi cago seemed to be overshadowed by hard currency questions As far as the general news media was concerned the Chicago trade show was rather neatly summed up by the Wall Street Jour nal s headline for its main CES story Consumer Electronics Industry Re mains Beset by Strong Yen Little Inno vation General coverage of the show in fact seemed to relegate the CES to just another trade show in contrast to last year and 1985 when the press dis covered the glamour of consumer elec tronics Particularly in those years major newspapers and magazines gave the Consumer Electronics Show the kind of razzle dazzle treatment usually
81. 1 12 000 ohm 4 watt 5 resistor R2 R4 1200 ohm 4 watt 5 resistor R3 2500 ohm ten turn trimmer potentiometer U1 741 op amp or similar integrated circuit UNREGULATED REGULATED V V O e HI 12K R4 10K COMMON COMMON eegen REGULATED V ct UNREGULATED 02 V MPS2907 Fig 2 This circuit is an expansion of the basic regulator circuit amounting to a dual polarity op amp based voltage regulator circuit that s referenced to common ground 01 TIP3055 REGULATED C e UNREGULATED V V COMMON Fig 3 Transistor Q1 is configured for series pass oper ation and is controlled directly by the output of U1 The reference that s applied to the non inverting input of U1 at pin 3 is determined by resistor R1 and zener diode D1 have the circuit breadboarded and working measure the voltage at various points within the circuit both with and without an output load and adjustment to R3 You might also want to experiment with different values of R1 and D1 Dual Power Supply Figure 2 is an expansion of the basic circuit shown in Fig l which amounts to an op amp based dual polarity voltage regulator circuit that s referenced tocommon ground Let s examine the positive portion of the regulator first The V regulator circuit comprised of U1 Q1 D1 R1 R2 and R3 is shown separately in Fig 3 for convenience In Fig 3 as in Fig 1 Q1 is controlled by the output
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83. 5 volts The potentiometer is used to vary the input voltage You set it to zero initially The output voltage should have been about 8 5 volts or the saturation level of the op amp Here the op amp is responding to the 4 5 volts applied to the non inverting input Varying the potentiometer to increase the input voltage in a positive direction caused the output to switch from 8 5 to 8 5 Measuring the potentiometer voltage you should have found it to be about 4 5 volts or slightly higher Remember that the comparator switches when the two inputs are very nearly equal In Steps 14 16 you connected the integrator to the com parator You let the integrator charge to the negative supply voltage producing a positive output ramp When the ramp reached 4 5 volts the comparator switched The integrator rate and the comparator reference voltage determine the time it takes for the comparator to switch Rearranging the integrator formula we can compute for time instead of voltage t VVORC INTEGRATOR COMPARATOR 9V Fig 14 Connecting the comparator and integrator circuits causes the comparator to switch states when the integrator has been operating for a certain time and reaches 4 5 volts 864 H38OLOO eo o HANDS ON ELECTRONICS co o We substitute 4 5 volts for V because that is the value of output that will cause the comparator to switch t 4 5 9 1 10 000 x 000001 t 4 5 9 5 seconds Your ti
84. ACNAP put this program to work analyzing AC networks leaving yourself free to handle the important stuff Using Op Amps In Power Supply Circuits understanding op amps in power supply applications Fuse Applications and Selection learn how fuses are used to protect your electronics equipment and appliances Servicing Audio Amplifiers with nothing more than a multimeter you can repair your high power audio equipment while pocketing the change Learn By Doing op amps are the most adaptable integrated circuits but you can t use them unless you understand them Friedman On Ccraputers page 20 HANDS ON REPORTS Persoft Referee Program a utility that manages Ram resident software SPECIAL COLUMNS Friedman on Computers get more out of your computer by stretching your budget a bit to add hard disk storage Solcering 3tetson page 34 Jensen on DX ing what country s flag is red white and blue is governed by a constitution and is not the United States Saxon on Scanners full spectrum capabilities come to scanners Carr On Ham Radio learn how the radiowave propagation phenomena lets signals originating in one hemisphere to be heard in another Ellis on Antique Radio Echophone EC1 the restoration continues Circuit Circus exploring voltage doubler multiplier circuits illustrates how a high voltages can be generated from low voltage sources Wels Think Tank reader interactivity continues and you s
85. ACNAP is an acronym for the AC Network Analysis Pro gram a BASIC computer program to solve for the node voltages in AC alternating current networks The listing for the program is given in Listing on page xx Although the listing is for machines that utilize the Micro soft version of the BASIC language the program is easily modifiable for just about any PC with at least 32K of random access memory RAM To help you with those modifica tions a special section of this article has been dedicated to just that issue At this point many of you are doubtlessly thinking about not reading the rest of this article You d rather just start entering the program in order to speed things up Let me give you a word of advice Don t The time you spend now learning how the program is structured and how it is intended to be used will help you ten fold later on when you try to find your typos That is especially true if your computer doesn t use Microsoft BASIC and you must make slight modifications to Listing on page xx Another reason to refrain from skipping ahead is that ACNAP like any other program has some limitations which should be understood and some conventions that must be observed By understanding what those are and why they exist you will be better able to use the software and more confident in its solutions T WORLD S FIRST ELECTRONIC DIGITAL COMPUTER THE ENIAC With all that in mind let s turn our attention to a
86. ADGET is published by A G Consultants Inc 116 W 14th Street New York NY 10011 212 989 8001 Copyright 1987 by A G Consultants Inc GADGET is a registered trademark of A G Consultants Inc GADGET is published 12 times a year and appears as an insert in Hands On Electronics published by Gernsback Publications Inc Farmingdale NY 11735 For information on subscriptions to Hands On Electronics please see the magazine s editorial page Letters intended for GAD GET s editorial staff should be sent to the newsletter s address as shown here GADGET s soie commitment is to its readers in order to avoid even the appearance of a conflict of interest GADGET does not accept advertising nor does GADGET solicit gifts or other benefits from manufacturers and retailers who may be men tioned in reviews Page 2 GADGET OCTOBER 1987 Touch Zone WORLD TIME TOUCH SENSOR Manufactured by Seiko Time Corp 640 Fifth Ave New York NY 10019 Price 89 50 We re slightly chagrined here at gadget central Hardly had we finished telling readers about the high priced Geochron World Time Indicator August p 5 when our publisher discovered a similar device which does nearly the same job at nowhere near the same price A product of omni active Seiko Time Corporation the World Time Touch Sensor digitally provides the correct time in 27 different time zones at a touch or two of the finger Measuring 734 by S4 the World T
87. C users in one de partment might need Prokey with Lotus 1 2 3 but then need a spelling checker Team for Lotua 123 rokey Ready SideKick Sideline programa shown in loeded order Main menu d Show dets lad info eyboerd Useg Move cursor Mein menu UNLISTED RES PROCS D Cursor to firet E Cursor to lest when they switch to word processing software Referee can be configured to enable Prokey but no other RAM resi dent programs when the user is in l 2 Then when the user switches to word processing Reteree will invisibly disable Prokev and enable the spelling checker Sounds simple It is and it can do it for the PC XT or AT or clone installing Referee Releree is compatible with your IBM PC XT AT and compatible microcom puters that have at least 128K RAM one disk drive and PC DOS 2 0 or later Begin by using the DOS COPY com mand to copy all of Referees files into Continued on page 103 Active within Lotus 123 Wot active within Lotue 123 Stetue unchenged within Lotus 123 SE Toggiee status Bienk for ites Fig 2 RAM teams are those HAM resident programs you would want to use with a particular program Here the RAM Team for Lotus 123 are Prokey Ready Sidekick and Sideline The sign means that the program will be activated minus deactiv ate and no sign means that the status will remain unchanged For more information circle no 81 on Free Information Card
88. DER FORM To run your own classified ad put one word on each of the lines below and send this form along with your check to Hands on Electronics Classified Ads 500 B Bi County Boulevard Farmingdale N Y 11735 PLEASE INDICATE in which category of classified advertising you wish your ad to appear For special headings there is a surcharge of 10 00 Plans Kits Business Opportunities For Sale Education Instruction Wanted Satellite Television Special Category 10 00 PLEASE PRINT EACH WORD SEPARATELY IN BLOCK LETTERS No refunds or credits for typesetting errors can be made unless you clearly print or type your copy Rates indicated are for standard style classified ads only See below for additional Charges for special ads Minimum 15 words 10 15 21 00 18 25 20 19 26 60 20 28 00 25 35 00 26 36 40 27 37 80 28 39 20 29 40 60 30 42 00 31 43 40 32 44 80 33 46 20 34 47 60 35 49 00 We accept MasterCard and Visa for payment of orders If you wishto use your credit card to pay for your ad fill in the following additional information Sorry no telephone orders can be accepted Card Number Expiration Date SIGNATURE PRINT NAME IF YOU USE A BOX NUMBER YOU MUST INCLUDE YOUR PERMANENT ADDRESS AND PHONE NUMBER FOR OUR FILES ADS SUBMITTED WITHOUT THIS INFORMATION WILL NOT BE ACCEPTED CLASSIFIED COMMERCIAL RATE for firms or individuals offering commercial
89. DS ON ELECTRONICS seconds being multiplied by seconds while the constant term is given in degrees Although that may seem a bit un usual such equations are generally written in that format Because it is so common ACNAP displays the node volt ages in polar coordinates using that convention That bring us to the last rule Rule 5 It may sound very restrictive but don t worry it doesn t have to be followed at least not totally Let me explain If Rule 5 is followed ACNAP will correctly handle inde pendent voltage sources ACNAP however will still give correct answers if Rule 5 is broken just as long as it is broken in the correct way Suppose you have a circuit with three IVS all in a row as shown in Fig 2 When numbering the four nodes related to the three IVS make certain that they are numbered in sequential order For example 1 2 3 4 as shown would be a correct labeling but 1 3 2 4 would not be correct The other thing you must do is to enter the independent voltage sources into ACNAP in reverse order the IVS con nected to the highest node number must be entered first the VS with the second highest node number must be entered second and so on In Fig 2 the correct order would be IVS 3 IVS 2 and finally IVS I If those steps are taken ACNAP will be able to correctlv solve circuits which have two INS sx connected to exactly v 1 VU v 3 Fig 2 Voltage sources must be assigne
90. EO 1 3 4 X 3 1 2 TWO PANELS ROUNOEO CORNERS CABINET ANO PANEL DIMENSIONS Fig 3 Here are the cabinet s surface dimensions Fasten top and side panels to the cabinet and round off the corners together with a bench or portable sander Drill out the ends of the slotted tube areas with a inch circle cutter connections of L2 to C3 as shown in Fig 1 capacitor Tie the ground and antenna wires to their respective posts Connect the 9 volt transistor battery B1 terminal to the on off switch SI which is a part of the volume control R5 terminals Wire up the stereo headphone terminals to JI Mount Ul be sure that pin of UI sits at the correct position in the socket Now double check all wiring An 8 to 39 ohm low priced light weight stereo headphone works nicely here Power Up the Radio The antenna radio should be tested before the front panel is mounted to the cabinet Plug in the earphones and battery Turn the volume control full on Now rotate the regenration C3 control until a squeal is heard For best results a 50 ft outside antenna and a good earth ground should be used Rotate the variable tuning capacitor and notice several squeal ing stations on the band Readjust the regeneration and volume control for normal earphone listening Fasten the coil in position with rubber silicone cement Troubleshooting the Radio Double check all wiring 1f the radio does not operate the first time If VOM or DM
91. M is handy take voltage and current measurements Insert the DC 20 milliampere meter leads in series with one lead of the battery If the radio is dead and the meter indicates heavy operating current over 20 milliamperes suspect a leaky transistor or If antique knobs are not available make some of your own The round dial assembly was made from a piece of plastic with lines drawn through with a small soldering iron Two coats of silver metallic spray paint makes it appear like a metal dial IC This little radio pulls only 10 7 mA with the volume clear down and 13 9 mA with a strong station turned in No current indicates voltage is not applied to the correct C or transistor terminals Take critical voltage measurements on the IC and transistors Compare your operating voltage measurements with those found in the schematic diagram Fig 1 Make sure that Ul is inserted into the socket with the polarization dot or slot near pin 1 Re check the bottom view of each transistor connected with the circuit If Q2 does not oscillate or make a squealing noise as the regeneration con trol is advanced re tap the coil at the 7th or 8th turn from the ground end of L2 For added volume try reversing the terminals of LI Old Tube Mounting To make the antique radio have a vacuum tube operating Continued on page 106 KNOB TOP VIEW NUT ANO BOLT EPOXY BRASS KNOB L INSERT SET SCREW I 1 3 ai 5
92. ND i BP135 SECRETS OF THE COMMODORE 64 5 00 Masses of useful info and programm mung tips not found in any user s manual BP130 MICRO IN TERFACING CIRCUITS BOOK t 5 75 Practical add ons transform your computer into control Of measure ment equipment P183 AN INTRO DUCTION TO CP M 5 75 To run and use tams operations under CPM you need this book BP104 ELEC TRONIC SCIENCE PROJECTS 5 75 Simple to complex a group ot projects with a strongly Scientific flavor 20 Programa tar the ZX Spectrum A wen EKEN 8P128 20 PRO GRAMS FOR THE 2X SPECTRUM A 16K ZXB1 5 75 All programs run on both machines include tlow charts and into on how to modity to run on other computers 8P51 ELECTRONIC MUSIC AND CREATIVE TAPE RECORDING 5 50 Shows how you can make electronic mu sc al home with simpte and inexpensive equip How te Dee gn Electronic Projects wir BP143 INTRO TO PROGRAMMING THE ATARI 600 800 XL 5 00 Perfect comple meni to the Atan users manual Even shows how to use animated graphics BP131 MICRO IN TERFACING CIRCUITS BOOK 2 5 75 interfacing sound and speech generators temperature and optical sensors motor control lers and more See o Get Your BP127 HOW TO DE SIGN ELECTRONIC PROJECTS 5 75 How lo use Standard cv cust elements to make Custom lectronmic pror ects BP92 CAYSTAL SET CONSTRUC
93. NIC BUILD ING BLOCKS Book 2 5 75 Amplifiers for all kinds 10 add Io the Gircuils trom Book 1 ol thus Serres BP169 HOw TO BP65 SINGLE IC BP49 POPULAR BP97 IC PROJ BPBO POPULAR PROJECTS 4 95 ELECTRONIC PROJ ECTS FOR BEGINNERS ELECTRONIC CIR All projects in this book ECTS 5 50 A 5 00 Written es CUITS Book 1 5 00 are based on one IC and ate simple to construct Great way to gel slarted wath ICs CHECK OFF SHIPPING CHARGES IN USA amp CANADA 0 01 to 5 00 5 01 to 10 00 10 01 to 20 00 20 01 to 30 00 30 01 to 40 00 40 01 to 50 00 50 01 and above 1 00 1 75 2 75 3 75 4 75 5 75 7 00 LJ L b a D THE BOOKS YOU WANT American types BP 7 MICRO GET YOUR COMPUTER PROCESSING PROGRAMS RUNNING SYSTEMS AND CIR 5 95 Have you ever BJ CUITS 5 95 Guide written your Own pro to the elements of micro processing syslems Teaches all the tunda rams Onty to find that do not work This book shows you how lo mentais find errors Deene T IC erogecis Eie ironic inio the Jor Beginners Circus OL Archive Boami t ddsldgl More circuits for hob byrsts Audio radio test music household and collection ol a wde range ol electronic projects and crcutts for the expen pecially lof the less experienced expen menter Complete parts menter layouts and winng di more BP98 POPULAR BP161 INTO THE ELECTRONIC CIR OL
94. New York NY 10018 is probably its low retail price Not that this timepiece built by Japan s Hattori Seiko Co Ltd doesn t have a number of attractive features Water resistant to 200 feet the MWS 8 sports watch has eight functions alarm and chronograph hour minute second day date and month Its laser regulated quartz movement is said to assure accuracy to within 20 seconds a month It comes equipped with a black resin strap and NDQ Marketing is certain that its streamlined styling will appeal to both male and female sports enthusiasts The watch also comes with a one year limited warranty with the company claiming a defective rate of only one third of one percent Price 9 95 Traditionally anyway the kitchen isn t thought of as a place of enter tainment dedicated as it is to preparing and consuming foods General Electric Consumer Electronics Electronics Park Syracuse NY 13221 however knows that the modern kitchen has changed Hence the com pany s introduction of a Stereo Kitchen Entertainment Center part of the very successful Spacemaker line of appliances The unit model 7 4269 mounts easily under cabinets and features an AM FM stereo radio and cassette player with two front fired speakers for full stereo sound Sold with the hardware necessary for mounting it can also be used on a counter or table top Besides its entertainment functions the 7 4269 also includes a digital clock k
95. O LOG 4 95 PRACTICAL ELECTRONICS Practical radio antenna designs that deliver good pertormance and are te atively simple and inexpensive to build Gs THE COMPUTER CON TROL OF ROBOTS 5 00 Dala and circuits lor interfacing the com puter to the robot s motors and sensors BP134 EASY AOD ON PROJECTS FOR COMMODORE 64 VIC 20 BBC MICRO A ACORN ELECTRON 6 95 Picture digitize aght pen modet conlrol let and more CALCULATIONS ANO FORMULAE 9 00 Companion volume to 8P53 Book carrers on wilh new dala not found in earher editon 450 pages An up to date directory ot AM FM and TV stations including a section on woridwide shortwave sta tions BP125 25 SIMPLE AMATEUR BAND AN TENNAS 5 00 A kinds of antennas for all kinds of amateur radio reception iter rational Transistor Mew te Get Your Eqevatents Computer Programs Gunde 1v d ws 6 a BP55 ELEC TRONIC SECURITY DEVICES 5 00 Three basic seclions Switch activated alarms infrared amp ukrasom sys tems smoke gas water detection BP85 INTERNA TIONAL TRANSISTOR EQUIVALENTS 7 50 Locates possible substitutes for a popular user onented selechon of modern Iransistors Japa nese European and BP117 PRACTICAL ELECTRONIC BUILD ING BLOCKS Book 1 5 75 Build the blocks and then combine them to form almost any Custom project of your choice BP115 PRACTICAL ELECTRO
96. O MPO NPO NPO WE totai ec p 5f 500 eec o He M 4 00 00 M total x sop Wire wrap poets heki te tros position of 019 pro An a 500 bon Tien E accidet viding true poeton of GBF on boars fes et i ade dell 0 Ch mn omnetc wie mera nor eng op YOUR CHOICE tim OR GOLD Aum E mient TEE anto om WC emeng c T t 300 Ki TEXAS tuSTRUMENT S QUALITY adm S SH ORO CEET E e ao J B we te e ZK 4 75M 4 ha ARN ey A pees JAM IND ON 481 SNN Baal DE 7450 ag 1 PEN TIN PLATED WIRE WRAP we me Beete nio e aan For Comotere Scacs on Phyeital Sirs mud C iectrical 41078 7ASOBN quee a A EPan as Beergtwen a 1 Crerectertation consu vow FREE DUO KEY Catetog H f d Ke 9 an 1 Metal Film Fized Resistors AS3DRTINAT C5 1 1 zg LA fe Sf 3858854 45842 dere 2 BEE BEASBJAXJ S 565555 ZAC Se BEAGR a O9 74S09N Ve a Fro in fe POPUL Aa v rut CAT NO OH K i ON Y avait 748228 gt gt d 24 34 4AN 245 30N Fett bw S ma D mee n Ew j of amm PANASONIC LS SERIES 745404 X t J41 0N gt We v d Cerner e lure d y Can 4191N 74851N 4 x GOLD INLAY WIRE WRAP te men Sett Mas Wortung voltage Minen C III s ors JASOAN 1 5 j Part Be Een 4 teg Las a 41574A r 34S RE M FAS C HSIN VUEN 74 113N MEIN S114N MN HOA 7451384 OKT 45135 GK 4 139 le i gies 19S 40N C24 1E SA SISIN e O1G aEY j De Key a NK P E 4 Oth 24 Pert Be 1 4 wen Me Fam henortren
97. OD D Visa D Mastercard e NO COLLECT CALLS e IMPORTANT e When ordering please have the make and model number of the equipment used in your area Thank you Call for availability Prices subject to change without notice AcctL 8 CE Date Signatur FOR OUR RECORDS state laws Dated Signed Jerrold is a registered trademark of General instruments Corp THE BEST BUY DECLARATION OF AUTHORIZED USE the undersigned do hereby declare under penalty of perjury that all products purchased now and in the future will only be used on cable TV systems with proper authorization from local officials or cable company officials in accordance with all applicable federal and 86L H380120 an o HANDS ON ELECTRONICS Good as Gold The 70 Series Multimeter The Shining Standard By Which Others Are Measured These multimeters give you solid value for your money A 3 year warranty keeps you from paying the price over and over for lesser quality meters Choose from either the basic 73 or the feature rich 75 and 77 You ll find the features you need at the price you can afford Touch Hold for holding readings Audible tones for continuity checks Autoranging for simple operation Uncompromised quality at competitive prices Get your hands on a 70 Series Multimeter at leading electronics distributors nationwide Or call toll free 1 800 227 3800 ext 229 for more information FROM THE WORLD LEADER IN
98. Puerto Rico 218 681 6674 Telex 62827914 FAX 218 681 3380 TWX 9103508982 DIGI KEY CORP NATIONAL SEMICONDUCTOR e PANASON piq ODES e DIAMOND TOOL e UNGAR e OK MACHINE e EWC INC INTERSIL AD 256K 262 144 x 1 DRAM 150NS 50 1 39 95 9 es CW INDUSTRIES gt AMDEK GE EAC INC e J W MILLER e AAVID ENGINEE 4 8 JGAR e YAGEO e J W MILLER e LUXO EE JOHNSON ATLANTIC SEMICONDUC PE Factory Firsts 3C CHEMICALS ARIES PLESSEY 5 Carbon Fim Resistors SOLOER TAIL DIP SOCKETS Senge basm Low Profis YOUR CHOICE TIN OR GOLD Am H gege guia gaben un quod epuer BB D Sa 5AN amp C917N 4C 18 bel AC II FRAG 2E EXYSRREE F J4L 191 al JaAL 195A 9v MLS gy 7 DN WIR kel 4 SAM MiSHIN TIN PLATIO SOLOER TAN i5 H Ban fe g ta we Port ng Deed ai CS f d Eg LTC EE z ae g 4t 24 Deranger 413244 POL 249 4152316 Hi 5 253 As d EBJ JSa34 9SSEH S Na 163349 3 1343558 Mane To Order vc E the Ow prie GOLD INLAY SOLDER TAN se ny Seegen ge RE 7 7777 7 e vc Prece Pon s Oomrgtas m 108 C9808 3 2 b o0 Raz SY S88 SB e s e T 1 8 wan Carton Fim Acsortrmanta amp atc of the T tended vaher FISSS HABE REESE EESE YR sach of rhe 72 stand a FSS WeSES SEEE WIRE WRAP mo x aq DIP SOCKETS 1 4 Wert Carton Fim Assortmen o Ka S 1 Regester T3 orandiard dues in 24 ei 2 Strderd profite ta t NPO KPO NPO NPO MP
99. R INPUT SUBROUTINE 1 amp RRRRRRRRRRARKRHARTRRERKER 3750 PRINT PRINT 3760 PRINT sx2x2222222ee2 UPOS d4 U I sesseesees 3770 PRINT 3780 PRINT P1S 3790 INPUT IN IF IN gt N OR IN lt O THEN BEEP GOTO 3780 3800 PRINT P2S 3810 INPUT mm EN IF EN gt NOR EN lt O OR IN EN THEN BEEP GOTO 3800 3820 PRINT P3S a 3830 INPUT VL IF VL lt O THEN BEEP GOTO 3820 3840 RETURN 3850 3860 1 3870 de n de d gd d e x kk t t t INPUT SUBROUTINE d Z BRRRRRRKERRRARRRRERRRERREE 3880 PRINT PRINT 3890 PRINT s22z22z222z POS 4g U I zz2ss22222z2 3900 PRINT 3910 PRINT P1S 3920 INPUT IN IF IN gt N OR IN lt O THEN BEEP GOTO 3910 3930 PRINT P2S 3940 INPUT EN IF EN gt NOR EN O0 OR N EN THEN BEEP GOTO 3930 3950 PRINT P3S 3960 INPUT MAG IF MAG lt O THEN BEEP GOTO 3950 3970 PRINT P4S 3980 INPUT mn ANG IF ANG lt 360 OR ANG gt 36C THEN BEEP GOTO 3970 3990 4000 VR MAG COS ANG PI 180 calculate the real component 4010 VI MAG SIN ANG PI 180 calculate the imagisary component 4020 RETURN Table 1 Those variables should be compatible with non MICROSOFT versions of BASIC Apple BASIC for ex ample only uses the first two terms tn vartable names Using ACNAP When you run ACNAP the first thing you should see is the introduction screen TT EE ok ok EE GG Gk ok ET coke oe eoe ke eo ceo ke eoe ek CEET EE ok oc oko oko o
100. R4 and R5 the DC Inverter will produce a negative oufpul vantage 12 TO 15V SOURCE C1 1 p F 100 WVDC Mylar SS 7T mi 25K By Charles D Rakes cam Ges Don t change power supplies produce what you need from what you have what you need from what pepe sprounce nmt yon ged trols what you have cw SE 2M Ge scheme deme dit ammmamema s about 80 of the positive power source The regulator circuit operates best with a load and when a regulated power source iS used the load no load output voltage will only vary a few millivolts Voltage Doubler Have you ever had favorite circuit or project that you wanted to use in your automobile but as fate would have it a part of the circuit required a slightly high er voltage than the I2 volts offered by the car s battery If so take a look at the DC converter circuit in Fig 2 A 555 oscillator timer configured sim ilarly to the one in Fig l feeds a positive voltage doubler circuit that produces the higher DC output voltage Transistors QI Q2 and diode D3 add regulation and a variable output function to the circuit If the regulator circuit is removed and a 12 volt supply is applied directly to the os cillator circuit top of C1 the output will be over 25 volts and will vary in level with supply voltage changes and load varia R4 2 2K R3 10 000 ohm Vz watt 5 tions An output current of over 30 mA can be supplied at a regulated ou
101. TABLE 1 FUSE SPECIFICATION CHART Fuse Applications and Selection How often have you wondered if the fuse you are using will save your equipment from the grim reaper for each current rating All of that serves to prevent the wrong size current rating fuse from being used when replacing a blown fuse In household applications the fuse size is deter mined by the gauge of the wire used to wire your house The electronics industry developed its own sizing system although the system actually started with the early auto mobile industry and the AG series of fuses AG stands for Automobile Glass The system however does not rely on any physical characteristic of the fuse to determine the fuse rating For example within each series various amperage ratings are available Now care must be taken when replacing fuses to insure you have the correct rating Table shows the physical dimensions for the fuses in the AG series along with the range of current ratings that are available The 3AG series has turned into a sort of generic brand name and is probably the most popular The major manufacturers however have chosen to apply their own num bers and they are also listed in Table 1 The AB nomenclature indicates that the outer tube of the fuse is made from Bakelite or ceramic materials and is used where glass type fuses would create a hazard if the glass cartridge should explode The Ratings Stamped on the end cap of the
102. TE DEVICES 1665P 17 95 Cem DIGITAL 2795 29 95 Counts as 2 wt 1529P 14 95 1599P 16 95 An absolutely no risk guarantee AN Select gt Books for only 3 and get a Free Gift Reg O TROLELESHOOTING A REARING age 1199P 16 95 4250P 14 95 2755 17 95 es b Elementary ae FUNDAMENTALS Electricity rmm e im TRANSDUCERS Electronics Component by Comparar m E E L 2792 21 95 1693 21 95 728P 10 95 Y ASi H PHAN K TS Kav AS fp Lanitin P WIE TE CELL olia ASIC ELECTRONICS HEOF el lt 8 vd Ce gas a 3H Ov T 4008 a M 1757 24 95 1775 29 95 Counts as 2 TROUBLESHOUTING AND REPAIRING SOLID STATE TYS 147 PRACTICAL IC PROJECTS YOU CAN BUILD _ as 1925 24 95 2707 24 95 2645 16 95 1987 ELECTRONICS BOOK CLUB Blue Ridge Summit PA 17214 All books are hardcover editions unless numbers are followed by a P for paperback CIRCLE 10 ON FREE INFORMATION CARD values to 135 70 FOR WORLDWIDE CONTROLLED SATELLITE TY RECEPTION eae mn e at man a neame LL Lm 1793 14 95 1531P 11 50 1909P 14 95 Lee QURE M MASTER SHORTWAVE SILICON CONTROLLED LISTENER S RECTIFIER PROJECTS S y 1586 17 95 PRINCIPLES PRACTICE IMPEDANCE gen 9 abd t aO 2725 21 95 2655P 16 95 1370 26 95 Membership Benefits Big Savin
103. THIS S THE THIRD IN OUR SERIES OF ARTICLES DESIGNED to teach you the operation and application of some of the more popular and widely used electronic circuits In this article we will explore some of the more interesting and usetul applications for integrated circuit operational ampli fiers IC op amps This article is written in a unique way It is not just an article that you read Instead it is a lab experiment with step by step procedures that you can follow to build and demon Strate op amp Circuits It will lead you by the hand in circuit construction and operation explaining each step as you go In addition to the specific circuit components listed later you will need some basic hardware to implement your experi ments The base for the experiment is a breadboard Any ot the various popular commercial types with Ulm spaced holes and room for three or four IC s will do nicely You will also need a power supply to run the circuits For op amp circuits two power supplies are needed both positive and a negative supply Any power supply that will furnish 120r 15 volts will work nicely If you do not have a power supply you can use two 9 volt transistor radio bat leries to power the circuits described in this article Simply purchase some conneciors with wire leads and connect the batteries as shown in Fig The batteries have sufficient power to handle the experiments described here Just be sure to disconnect the batteries
104. TION 5 00 A variety o crystal radio receivers for the expenmenter and hobbyist BP106 MODERN OP AMP PROJECTS 5 00 Includes a Side Timer AF Signal Gen Mre Pre amp Scratch Filter and much more BP185 ELEC TRONIC SYNTHESISER CONSTRUCTION 5 95 Shows how to build a monophonic syn fhesizZer section by section Replaces BPB1 GREAT PAPERBACKS AT SPECIAL PRICES 27051 CUSTOMIZED wiCRO PROCESSOR PROJECTS 14 95 Butang instructions de talked schematics and app Als programs tor Mithun And usehs ded ed CPU tQvects BP148 COMPUTER TECHNOLOGY EX PLAINED 5 00 Explanations for comput er terms often encountered A dictionary lor Computer lingo Quality Paperbacks BP110 How TO GET YOUR ELEC TRONIC PROJECTS WORKING 5 00 How to find the faults in your Projects repar them and get them working lectrorec Vitr rope ts BP59 SECOND BOOK FOR CMOS IC PROJECTS 5 00 Muttivibrators amplifiers triggers amp gates special devices inciuding reac tion timer simple eleclrone orgar more and ELECTRONIC TECHNOLOGY TODAY INC P O Box 240 Massapequa Park NY 11762 0240 Name Address City State 7 d j o H1087 Electronic Besgocg Projecta Linear IC Equivalents and Pin Connections BP141 LINE AR IC EQUIVALENTS AND PIN CONNECTIONS 12 50 247 pages 7 10 in shows equivs amp pin connections lor popular user onented ICS
105. The model PRC U has a suggested re tail price of 119 95 and is available from TV service shops mass merchants tele vision and appliance stores and other re tail outlets nationwide For further information contact the R L Drake Company PO Box 112 Mi amisburg OH 45342 Tel 513 866 2421 Preamplifier Equalizer Looking for an ultra compact car stereo preamplifier with seven band equalizer and subwoofer crossover Well the PS 7 CIRCLE 67 ON FREE INFORMATION CARD features front panel switchable tape and CD inputs high and low level tape in puts continuously variable CD input sen sitivity built in front and rear fader with outputs that can be full range or a 12 dB per octave highpass filter at 150 Hz The subwoofer crossover has a continuously variable crossover point 75 Hz to 150 Hz with a 24dB per octave slope The PS 7 is only one in high and fea tures LED equalizer position indicators which are also signal level indicators The model carries a 165 00 suggested retail price For additional information contact Al phasonik Inc 701 Heinz Avenue Berkeley CA 94710 Tel 415 548 4005 Real Time Spectrum Analyzer Here s a unique combination of spec trum analysis and digital oscilloscope utilizing the versatility of any IBM PC XT AT or compatible computer allowing the user to view both the input signal and its frequency spectrum in real time Useful anywhere spectrum analysis or event re
106. X fans will not only find a worthwhile improvement in signal noise ratio but also a reduction in beat note interference which occurs ing the slide change mechanism of the projector The monostable assures that the power to the relay is applied only briefly by the timer so that multiple operation of the projector Is avoided E RETE when two stations share the same frequen Cy AM Stereo amp High Fidelity Owners of hifi AM stereo receivers will find the improved signal to noise ratio of benefit particularly when the signal quality is only marginal with the normal antenna Shortwave Bands Useful improve ments were noted on both the 80 meter and 40 meter bands The added selec tivity and directionality of the loop often helps to reduce or eliminate interfering transmissions on nearby frequencies A long wire can give more signal strength but the loop generally gives better signal to noise ratio For international short wave transmissions the loop provides a neat and portable alternative to stringing up a long wire Other Receivers The loop was tried with various re ceivers including the Sony ICF 2001D which is a higher performance big broth er to the ICF 7600D Improvements were not as marked as with the smaller set as the ICF 2001D has a larger ferrite rod antenna and a better front end Nev ertheless the improvements were signifi cant enough for the owner of the set to
107. a front stereo ampli fier a rear stereo amp a crossover and a subwoofer amplifier in one compact CIRCLE 69 ON FREE INFORMATION CARD p H M Hn amet chassis in order to cut down installation headaches and ultimately enable installer to do more work in less time In five channel operation the DC A 3500 is rated at 40 watts X 4 and 80 watts X l atl kHzand 1 THD In three channel operation power increases to 80 watts for the subwoofer The built in sub woofer dividing network offers a choice of 80 Hz or 120 Hz crossover frequencies For added flexibility switchable high cut and low cut filters are also included They take effect at 12 dB and 18 dB octave respectively Mounted in the trunk the conventional car audio amplifier can see a ground potential different from that seen by the head unit mounted in the dash That difference will be reproduced as noise To solve that problem the Denon Real World Grounding system automatically senses voltage differences between the signal ground and the power ground The ampli fier applies an equal but opposite voltage to cancel supply induced noise The DC A 3500 also takes advantage of two technologies originally developed for Denon home amplifiers First Non Switching Class A amplification elimi nates crossover distortion from the output transistors Second Denon s Non NFB circuit design corrects
108. a go at winning a computer but you also get to share your ideas Who could ask for more from a hobby Hanging On read in one of your other magazines I forgot which issue you had a musical hold button that readers could build for their phone using something from a Hall mark card I m really interested in that device Unfortunately can t remember which issue it was in would really like to have an electronic hold button so that if put a phone on hold on any of my phones can go to any other phone and pick up at that phone instead don t want to worry about the hold button stili being on and having to speak from that phone or having to turn it off as soon as hang up Could you please send me some infor mation on it that would help me to design itfor my house and probably assist most of the readers out there with an interest ing and useful project J K Newton NH The issue in question was September October of 1986 The project you men tion will operate as you desire To turn the hold off just pick up any extension phone That should hold you for a while Coiled and Ready have a copy of the September Oc tober 1986 Hands On Electronics The story that intrigued me the most was The Ultimate Burglar Alarm by Byron G Wels and Robert M Wolet tried to construct the device but the diagram shows a transformer that the story does not mention My question is What size is that transformer or Wh
109. a resistance measurement to common ground and compare your readings with the good channel You may locate poorly soldered and shorted connections open bias resistors and defective new components with resistance measurements after IC or tran sistor replacement 38V HANDS ON ELECTRONICS j ds testing In many large amplifiers the transistors and IC s are layed out in line when the amplifier is viewed from the front This active loop antenna will dramatically improve reception on longwave broadcast and amateur shortwave bands By David Whitby THE LOOP ANTENNA HAS BEEN AROUND FOR A LONG TIME now In fact it was one of the earliest forms of receiver antenna used way back in the wireless days Over the years loops have been made in various shapes and sizes the larger ones usually being made in the form of a spiral or solenoid coil wound on a wooden cross or box frame as shown in Fig 1 At one time most portable and many domestic sets con tained a built in loop antenna The introduction of the ferrite rod or oopstick antenna as it was first known soon dis placed the loop in portable and domestic radio sets The reason for that is not because the ferrite rod was necessarily a better signal capturing device but that it was smaller in size and easier to mass produce It can be readily demonstrated that the signal capture of a ferrite rod is approximately equal to that of a loop antenna with a diameter
110. ablished company who will be here for you time after time We may be tough competitors but we ve got a soft spot for our clients Try us and be treated right and we ll prove it by giving a one year warranty on everything we sell Check our prices on Scientific Atlanta Units face it There will always be some outfit ITEM ITEM RCA 36 Channel Converter Ch 3 output only f Minicode N 12 with Vari Sync Panasonic Wireless Converter our best buy E Minicode VariSync with Auto On Oft 400 or 450 Converter manual fine tune Econocode minicode substitute Econocode with VariSync MLD 1200 3 Ch 3 output MLD 1200 2 Ch 2 output Zenith SSAVI Cable Ready M 35 B Combo unit Ch 3 output only interference Filters Ch 3 only M 35 B Combo unit with VariSync j Eagle PD 3 Descrambler Ch 3 output only Minicode N 12 i Scientific Atlanta Add on Replacement Descrambler CHECK US OUT WE LL MEET OR BEAT THE OTHER S ADVERTISED WHOLESALE OR RETAIL PRICES Pacific Cable Co inc California Penal Code 593 D forbids us from shipping any cable descrambling unit to anyone residing in the state of California Prices subject to change without notice PLEASE PRINT Shipping Add 3 00 per unit COO amp Credit Cards Add 596 7325V Reseda Bivd Dept H 10 name Reseda CA 91335 Address City 818 716 5914 e 818 716 5140 State Zip PhoneNumber O Cashier s Check O Money Order D C
111. affect on the output The actual voltage will be equal to the sum of the input and bias currents times the feedback resistance Vour in 1 X RI For obvious reasons an op amp with the lowest possible input bias currents should be selected for this application Figure 6 shows a circuit for going in the other direction voltage to current conversion It s typically used to drive relays or analog meters The feedback resistance is the load being driven perhaps the coil of the relay or an ammeter The current flowing through the load is determined by the input voltage and the value of resistor R1 and is given by I V RI out The load current l1 is entirely independent of the value of the load resistance which is usually quite small A voltage to current converter circuit of this type is also known as a transmittance amplifier Fig 6 The voitage to current converter also known as a trans mittance amplifier is LOAD typically used to drive relays or analog meters The load current I is entirely independent of the load resistance The circuit in Fig 6 uses the inverting input so the signal polarity is reversed If that s undesirable in your particular application the non inverting voltage to current converter 861 H380120 o HANDS ON ELECTRONICS o N Fig 7 The non invert ing V to C converter is almost identical to the inverting version shown LOAD In Fig 6 other than a simpl
112. after each session so you will not exhaust them prematurely The Ol wF disc capacitors are used for decoupling to prevent circuit oscillation and in stability You may not actually need them Finally you will need some test equipment A standard VOM tor measuring voltage and resistance will come in handy Some of the time voltages will switch from positive to 9v gt 01 TRANSISTOR D GROUNO RADIO T T BATTERIES SC D Fig 1 This simple power supply circuit is all you ll need to perform all the experiments in this column Note the use of capacitors to squelch any power surges due to changing load conditions yes they re necessary for DC applications By Louis E Frenzel Jr Op amps are the most adaptable integrated circuits but you can t use them unless you re taught how so here s how negative which will force you to switch your test leads around if you don t have a DMM That can be avoided by using the circuit described in the boxed text entitled Comparator Output Indicator An oscilloscope is also a desirable addi uon Most of the curcuit you will be able to demonstrate with a voltmeter but you will get far more out of the experiments if vou use an Oscilloscope earning Objectives When you complete the experiment you will be able to Explain the basic operation of an IC op amp 2 Explain the operation of basic op amp circuits including the inverter non inverting amplifier follower and differe
113. ain control action of most good receivers tends to mask the tuning and directional maxima of the loop signal by compensating for a wide range of input levels That is where the level control helps By initially adjusting the signal to just below the AGC threshold so that the signal is just audible both the tuning and the direction of the loop may be accurately adjusted for maximum perfor mance After that it s simply a matter of bringing the output level back up again to apply the full signal to the receiver input In cases of very high field strengths the loop output may also be reduced to prevent receiver overload Position 2 of S2 shorts the loop to prevent damage to the FET when the loop is placed in close proximity to a transmit ter as when the loop is used as the receiving antenna in an amateur station A relay could be used to perform the same function automatically during transmission if desired Power Power for the JFET butter is provided either from a 9 volt battery or main power pack Consumption is 2 to 3 5mA at 9 volts The power is switched on when the loop is placed in the active mode and off in the passive mode or the short circuit position Note that diode DI is included in the power pack circuit to prevent damage due to accidental polarity reversal Construction The kit is supplied ready to assemble and no drilling or panel cutting is required However if you would rather create your own circuit board a
114. alter to get ACNAP to run on your system Because have an Apple computer the Applesoft equivalent commands when different are also given 1 CLS Used through out the program CLS stands for clear screen HOME is the Apple equivalent command 2 LOCATE r c That statement positions the cursor on the screen at row rand column c in preparation for a PRINT command Apple uses VTAB and HTAB commands to perform the same function 3 CLEAR Used only on line 1020 that command clears all the program variables That statement can generally be 861 4380190 5 a HANDS ON ELECTRONICS E o eliminated without disastrous repercussions 4 SCREEN 0 0 0 0 That statement puts the computer into text mode as opposed to a graphics mode Apple uses the TEXT command for the same function amp COLOR c That statement sets the color that will be used to write screen text Those statements may be elimi nated altogether if your system does not support that func tion or if you have a monochrome monitor 6 WIDTH 80 Because of that command in line 1030 80 columns of text characters can be displayed on the screen at a time If your computer does not have an 80 column mode vou may wish to reformat ACNAP s PRINT state ments so that its output looks better on your screen 7 SQR x That command takes the square root of the number or expression in parenthesis If your computer does not support that function try raising the expre
115. am radio for three days I can t think of a better way to do it I know that PIE be back next year Well that about does it this time around but hope to see you next month Until then happy collecting T with contact cleaner spray and operated several times to prevent locking prior to reassembling the chassis and panel A frontal view of the reassembled Echophone The top panel containing the speaker won t be replaced until the set is operating and needs no adjustment 486l H380100 zech A Tue CIRCUS THIS MONTH STARTS OFF with a circuit that goes from positive to negative in a flash without the aid of that long standing nemesis Mr Murphy and ends up being a working and useful circuit that could fit in your next project DC Voltage Inverter Doubler The DC Voltage Inverter Doubler cir cuit shown in Fig I turns a 12 to 15 volt positive power source upside down creating a variable regulated negative supply The negative output voltage can be set to any voltage level between and 10 volts when the circuit is operated from a 15 volt power source and can supply up to 20 mA of operating current to a con nected load A 555 oscillator timer operating as a free running astable oscillator feeds its output at pin 3 to a voltage doubler circuit that is connected for a negative output Without the unusual feedback circuit components
116. amp circuit on an input signal Most op amps operate from a pair of power supplies usually positive and negative supplies of equal voltage The most common values are 12 or 15 volts Sometimes you will see the connections to the power supply as shown in Fig 2 n most of our examples here we will eliminate the power supply connection to simplify the circuit drawings Just be sure that when you build the circuits you include the power connections POSITIVE SUPPLY VOLTAGE V INPUT C INVERTING _ ie OUTPUT D NON INVERTING INPUT V NEGATIVE SUPPLY VOLTAGE Fig 2 The power supply connections will not be shown in the diagrams after this one You will assume they are used as shown here Note that neither goes to ground V Fig 3 This top view of the 1458 displays both op amps in the chip Note that both the op amps in the package share the same power supply pins pin 8 and pin 4 There are many different types of op amp IC s in use One of the more popular and longest living is the 741 It is packaged in an 8 pin mini DIP Amplifiers with similar characteristics are packaged two in a mini DIP An example is the popular 1458 which contains two op amps similar to the 741 Its pin configuration is shown in Fig 3 That is the device we will be using here Actually however almost any other popular low cost op amp can be substituted with equal ly good results Circuits By far the most commonly us
117. an t use right away and may not care about any PIS Den ARTT x Rte vam Ff Tei S S GA aes SA S S nh 7 PI as ees Te xia d aN Ki ZS E D A ihe CN p 89 Te w AEN Er i x gi 1 D EE S ei s Ze Tr i vi f SO VOURBOIUHT ih A SHORTWAVE RADIO CIRCLE 51 ON FREE INFORMATION CARD way the material is brief and basic with sources of more information provided tor each area discussed The book shows the reader where to tune for broadcast aero marine amateur and other stations pre sents lists of clubs publications and shortwave dealers all in a light and easy non technical style The book which contains 74 pages retails for 6 95 from Tiare Publications PO Box 443 Lake Geneva WI 53147 Tel 414 248 4845 The One Hour Commodore 64 By Tricia Jordan Ph D Studies show that the first hour in deed the first few minutes spends with a computer sets the pace for how that person reacts to and uses com puters Apple Computer certainly knew that when it spent millions ensuring that the first hour with a Macintosh would be easy friendly and successful This book follows in that trend Here s what you ll find in it setting up the com puter working with the keyboard setting up the cassette recorder saving and load ing programs on cassettes setting up the disk drive a bibliography to help you find more information booting up and explor ing DOS saving and loading programs on disk drives p
118. and MT2 falls below the triac s minimum holding current When the polarity of the AC input reverses the cycle starts again but with reversed polarity across Cl It must be noted that the triac does not conduct until the amplitude of the gate voltage reaches the breakover point even when RI is at minimum resistance The triac does not conduct unless the RC time constant is lower than the time required to change the amplitude of the mains below the breakover voltage of the diac Thus we cannot obtain 100 perhaps 2 98 regulation Note that the triac is either off or on but not in an intermediate state and therefore dissipates very little power One drawback of the circuit is that a certain amount of RF interference is generated due to the fast switching of the triac Although power loss is negligible in either end position of RI itis maximum in the middle position In that position the difference of the voltage being switched is maximum which leads to maximum power dissipation across the triac and increased generation of RF interference The circuit can be simplified by using only a triac diac Cl and RI Capacitor C2 and the inductor L1 decrease the RF interference caused by the switching action of the triac d 1N5760 f L J 2N6073 MT2 Fig 1 When the Temperature Controlled Soldering Station is turned on capacitor C1 starts to charge through resistor R1 When the voltage across C1 reaches the breakover
119. and state and timing displavs with hex octal and ASCII equivalents You can even use it in circuits with clock speeds up to 10 MHz trigger on any digital word and view events 2 000 pulses before trigger and up to 50 000 pulses after High impedance inputs virtually eliminate circuit loading And it s easy to use The highly intuitive user friendly software makes the IC 1001 fully keyboard configurable and menu driven All in one portable unit Put this most advanced technology to work for you for only 269 00 To order call toll free 1 800 253 0570 Ask for Operator 410 We also have 66 Heath Zenith Computers amp Electronics stores in North America Call 616 982 3614 for the store location nearest you CIRCLE 9 ON FREE INFORMATION CARD d worm n i 086 Saan E 7 Heathkit Company KB 103 HANDS ON ELECTRONICS N o By Don Jensen LIFTS FLAG IS RED WHITE AND BLUE ITs currency is the US dollar It was the first independent republic on its continent and it is governed by a President Senate and House of Representatives ts national Capital is named after a famous American president Sure its a trick question The coun try and our DX ing target this month is the west African nation of Liberia That Liberia s government is in many ways patterned after the United States is no accident It was founded by an organi zation called the American Colonization Society in 1822
120. andoned technologies His example was the rise of the internal combustion engine and what he suggested was that there were a number of alternative power sources being developed at the same time as the gasoline engine but which never came to fruition because their development was cut short by the supremacy of internal combustion Could that research be continued use fully today in connection with new technology What brings this intriguing notion to mind is the recent appearance of digital watches powered by a primitive Voltaic cell In the 18th century Count Ales sandoro Volta a scientist of the era discovered that when two dissimilar metals are immersed in water a faint electric Current is generated Moving on to the final quarter of this century contemporary digital time pieces require only the tiniest of elec tric Currents to operate Enter Ventu Research of Texas and presto the Water Watch was born This same coupling of primitive power generation and fairly advanced electronics in the service of timekeep ing actually surfaced a few years ago in the form of the Potato Clock which GADGET reported on in July of 1984 But VentuResearch s Water Watch ap pears to be the first miniaturization of this amusing hybrid of old and new technologies These timepieces available in several styles utilize tiny strips of zinc and copper separated by equally diminutive strips of what appears to be ordinary household style
121. another 555 circuit Electronic Wake up Call The first three circuits using the 555 were of the serious type designed to work capacitor resistor mE An JEN 0 with Or in another circuit or project but 2 irte 100 WVDC Mylar po c aia Ve watt 5 the aby A ag for m only A real e tomioo ery circuit W ever there was one c C3 10 pF 25 WVDC Electrolytic RS 25 000 ohm potentiometer No serious stuff with this one folks so dig O capacitor U1 555 oscillator timer integrated in ami havea ball iu C4 470 pF 25 WVDC Electrolytic circuit The Electronic Wake up Call circuit gt Capacitor Printed circult or perfboard mate shown in Fig 4 is designed to help you get 3 Rem ech general purpose Se etching solution power supply moving when sleeping is at its best Now S silicon diode or battery enclosure wire solder if you are against having a solar activated lt E e MD 2 Watt 5 hardware etc squawk box telling you when it s time to Ve MM Q1 2N222 10 15V Fig 2 Voltage Doubler o 1N914 Ue je R1 D2 REG DUT 2 2K Q2 CN 4 E 1N914 6 18V 2N2222 A len ALA o i Di 1 1 470 A m Se TENER C4 0 C1 47 pF Capacitor C2 10 pF Capacitor C3 470 yF 35 WVDC Electrolytic Capacitor C4 01 yF 100 WVDC Mylar Capacitor D1 D2 1N914 silicon signal diode D3 5 or 6 volt Zener diode U1 555 oscillator timer integrated circuit 25 WVDC Electr
122. application of op amps that seems to be relatively unfamiliar to most hobbyists and experimenters the use of op amps in power supply circuits In this article we will look at several basic op amp power supply circuits which will be presented primarily as experi mental circuits rather than practical complete projects You are strongly encouraged to breadboard and experiment with the circuits yourself as a way to learn about those versatile globs of silicon You may even find one or two of them useful in designing your own circuits or adapting them to your own projects No special equipment is needed to build or experiment with any of the circuits All that s needed is a VOM or DMM and some kind of breadboarding system If you have an all in one designer s breadboard with a built in power sup ply you re practically home free If not you can use an inexpensive solderless breadboard and any DC power Experimenting with op amp a deeper understanding of op amp applications supply that can put out about 9 volts You might even want to use batteries Aimost any standard op amp such as the 741 may be used in any of the circuits Although other chips may be used to suit your specific applications the 741 which we ll use wherever an op amp is called for is cheap enough so that you can freely experiment with it without being overly concerned about thermal meltdown If you blow one it won t hurt your wallet to sim
123. at am doing wrong M L W Des Moines IW The item you call a transformer is the coil for the relay K1 It is contained inside the relay housing as is indicated by the dotted lines The relay should have at least eight terminals two for the coil and three for each Switch However only two terminals are actually used for each Switch so familiarize yourself with the terminal layout and try again Good luck From High to Low Regarding Electronic Fundamentals in the March 1987 edition of your maga zine on pages 84 and 85 please clear something up for me On page 84 Fig 12B and Page 85 Fig 15B Shouldn the diagrams be reversed understand the i HB HP UM MH gegen outputs of low pass filters were taken from across capacitors Looks to me like the diagram in 12B shows the output taken across the resistor Also in 15B which is supposed to be a high pass filter it looks like the output is taken across the capacitor instead of the resistor Could there possibly be a mixup of the figures and should they have been reversed Perhaps do not under standing the definitions of the cutouts of LPF and HPF circuits would appreciate your clearing that up for me and thank you l m a subscrib er to your fine magazine and look for ward to each issue W J D Urbane AL You re right about the mix up the fig ures were transposed Both filters got passed us which indicates the need for a fi
124. ation 2nd Edition By Darold Wobschall Sure you can build projects but how about instruments This book presents vi tal information on the standard devices and techniques for the electronic design process and has been extensively revised and updated to reflect the latest changes in D 9 integrated circuit technology such as the shift away from TTL IC s to CMOS and ECL devices Filled with stimulating ideas on and practical solutions to problems in elec tronic instrumentation design the guide examines the entire process from input sensor to output display It includes both uc trumentation Simul Film CIRCLE 55 ON FREE INFORMATION CARD analog and digital circuits and empha sizes interfacing and the interrelation of circuits With 80 percent of the material in the second edition either new or thoroughly revised the book offers greatly expanded sections on sensors and communications The author has also updated the circuits to employ newer and better devices provid ing sufficient design information to allow for the construction of simpler circuits Subtitled Analog and Digital Devices From Sensor to Display this reference has full coverage of everything from semi conductor devices and basic circuits to signal amplification and processing from data switching control and readout to power circuits It explains in detail such diverse topics as temperature sensors electro optical devices displacemen
125. bove 7 00 All payments must be in U S funds OUTSIDE USA amp CANADA Multiply Shipping by 2 for sea mail Multiply Shipping by 4 for air mail D D D H D D D D D D D D D D H D E E RET Y T eM eR All the required information is in the data sheet that came with the drive In fact if you get one of the commonly used drives such as a Seagate 225 or a Micros cience 6 2 the controller data specifically lists the jumper block connections It s always best to use standard hardware Low level Format Now for the great bugaboo low level formatting of the hard disk which in non technical language means writing mag netic blips on the hard disk as reference marks for the regular format software Since IBM s DOS was intended for IBM s own hard disk drives which are prefor matted at the factory PC DOS does not contain a low level format program Ei ther you must borrow one from a friend or a BBS get it from the disk supplier if he has it or you simply enter a DEBUG routine that s given in the instructions supplied with the Western Digital control lers In about three to six minutes the hard disk is low level formatted and you can then use the regular PC MS DOS FDISK and FORMAT software to parti tion and format the hard disk for use Before we close we should put to rest two myths about hard disks which are usually used to intimidate hobbyists from saving a bundle of cash by using surplus hard dis
126. brator Touching the two upper contacts causes Q1 to conduct pulling its collector low thereby completing a path to ground through the load circuit carpet go to turn on the light and get zapped by a half inch arc from the static tried spray cans but they didn t last long enough and were too expensive However this circuit saved me When I come in now all have to do ts slam the front door and the lights come on Now send me my copy of the Fips book Clark Teicher New Orleans LA Clark it s on the way to you And don t mind telling you that l m in the process of building my own version of this unit as suffer the selfsame problem Check out Fig 3 The circuit stays off until a sound like Clark s door slamming causes it to activate The 741 op amp tn put stage is hooked up as a non inverting amplifier with about 100 gain If you need more sensitivity raise the resistance of R2 The signal is then rectified and filtered by the diodes DI and D2 and capacitors C3 and C4 The signal is ap plied to the base of transistor Ql a 2N2222 R5 sets the desired audio threshold and the output of the transistor at its collector is applied to a relay which activates the output load Make sure that the relay you choose will have sufficient capability to carry the current you desire at its contacts Phone Recorder If you ever have a need to tape record telephone conversations this becomes the handiest gadget in the
127. brief examination of the program s structure Program Structure ACNAP s structure is shown graphically in the general ized flow chart of Fig 1 The numbers in square brackets on that chart reference the line numbers of the program list ing associated with that block After the program is initialized on lines 1000 through 1060 two screens of text are displayed The first is a general overview of the program and the second is a summary of the major conventions and limitations of the program Those will be discussed in detail in the section on using ACNAP In lines 1600 1760 two network parameters are entered the number of nodes in the circuit not counting the ground node and the frequency ol operation of the circuit The number of nodes may range from to 25 Sinele node circuits can be solved by ACNAP very quickly but circuits with many nodes may take several minutes to salve The frequency may be entered in either Hertz Hz or radians per second Rad sec Keep in mind that ACNAP requires all power supply devices to have the same frequency of operation and it will give incorrect results if that rule is not observed One way around that limitation would be 10 use the principle of superposition The use of that principle however is beyond the scope of this article cop out 214 You can use ACNAP to solve DC circuits by setting the frequency of operation to zero hertz or zero radians per second If you do that however make c
128. ch application program A plus sign denotes active a minus sign denotes inactive and a blank denotes status unchanged within this application 4 Exit to DOS 5 As you access each application program Referee will automatically activate and deactivate the RAM resident programs according to the RAM Team specified for that application Don t forget Send in your Referee registration card Copyright 1986 Person Inc Madison WI 53711 All Fights Reserved Rieterne Sideline and RAM Team are trademarks of Person inc your PATH statement contains that sub directory Use the first menu Activate Deactivate RAM Resident Programs to manually activate deactivate and unload your resident programs Doing It Automatically You have the option to automatically control your programs with Reteree Just tollow the directions given above to load and access Reteree Use the second menu Tell Reteree about Your RAM Resident Programs to enter the tilenames of any Zei your EU Specify Applicetions amd their RAM Teens Exit Te DOS Referee c Copyright 1986 by Pereoft Iac Version 1 0 aroo 6 ane Bb Ara to move cursor H re select 101P8 7848 214 Fig 4 Here is what the main menu looks like when you first use Referee Read the excellent manual however the menus within the program directs and coaches the user fairly well get a user s manual and a packet con taining a floppy disk registration ca
129. cillator is generated by a relaxation oscillator consisting of a 2N4871 UJT Q1 operating at a frequency of 1 5 kHz Fig 5 Pressing switch S1 causes C1 rapidly to 7 volt biasing Q1 which allows current to flow and operate the relay Releasing S1 causes C1 to dis charge through R2 When the charge on C1 reaches about half a volt Q1 turns off and the relay opens NEI the NOR gates have both inputs tied to gether to act as inverters The remaining gate is used as follows Ula and Ulb form an astable multi vibrator with its operating frequency de pendent on the number of timing resistors switched into the circuit via S2 The tre quency is about one cycle for every five seconds with a single timing resistor one every ten seconds with two resistors etc That provides six switched time intervals Continued on page 105 1 DN DFF A Q 9V C3 22 1 4 4001 GND Fig 7 The auto advance circuit using a 4001 CMOS quad two input nor gate configured as inverters advances the slides at intervals of 5 10 15 20 25 or 30 seconds depending on the setting of switch S2 The fast easy and low cost way to meet the challenges of today s electronic innovations A unique learning series that s as innovative as the circuitry it explains as fascinating as the experiments you build and explore From digital logic to the latest 32 bit microprocessor the McGraw Hill Contemporary El
130. clud ing Arista A amp M MCA CBS Rec ords Chrysalis Capitol and Polygram Records as well as MGM UA CBS Fox Warner MCA Paramount and OCTOBER 1987 UniSynth Electronic Guitar RCA Columbia home video both the music and video industries are betting on this laser hybrid But from the con sumer standpoint the success of the CDV seems a long shot People buy 45s to sample the music of an album and decide whether or not to shell out for the entire LP Given the retail price level of the CDV 8 to 10 we don t think consumers will be rushing to buy a Single music video and two or three songs One observer quoted by the Wall Street Journal put it this way It requires a teen ager to buy a 600 player to play back a five minute video that costs 8 and that he or she has probably grown tired of already There was also a vast expanse of CES exhibition space given over to digital devices It seems that con sumers or maybe just marketeers were so amazed by the success of com pact discs that companies are now flooding the market with other dig ital equipment Of course there s DAT digital audio tape The cassettes look like videocas settes and the sound is truly outstand ing But the U S Congress is being heavily lobbied primarily by the big bucks record industry to pass legisla tion which would require that all DAT decks on the American market have a special microchip installed to prevent
131. cording is needed the digital os cilloscope features 4 channels of simulta neous acquisition 500K Hz sampling rate per channel 32K data buffer per channel full pre and post trigger up to 32K trig gering in analog digital external inter nal and single shot mode grid display lissajous plot of X vs Y using any com bination of the 4 channels print screen capabilities automatic channel calibra tion 10 mV to 50 Volt per division gain scaling user definable headings for spec trum oscilloscope displays save retrieve CIRCLE 68 ON FREE INFORMATION CARD data to from disk menu driven turnkey software and more The spectrum analyzer features 250 KHz bandwidth 1024 point FFT X or X amp Y cursor linear or log magnitude scal ing hanning or rectangular windowing spectrum averaging to 64 spectra varia ble or fixed scaling and menu driven turnkey software Special features include display of mul tiple plots on a single screen for easy com parison autoscaling of retrieved data to display screen parameters options can be changed without leaving the real time dis play by use of the F keys and color graph ics displays With a suggested retail of 2995 the system is available from Rapid Systems Inc 433 N 34th Street Seattle WA 98013 Tel 206 547 8311 Car Amplifiers High end car audio installations are more complicated and more expensive than they have to be But Denon s DC A 3500 combines
132. coverage of that band on Turbo Scan 800 is special For starters more convenient access Once the tre your scanner you can monitor birds such the Turbo Scan 800 takes advantage of quencies have been programmed the key as the three NOAA weather satellites 30 channels per second That s a quantum programming can t be accidentally MHz in addition to their microwave fre leap in scanning speed and almost five changed quencies above 1500 MHz There are times faster than most other scanners can The Turbo Scan 800 also offers a tea others too Checkout frequencies such as manage to operate ture which Regency has dubbed Accu 136 125 136 23 136 32 137 02 and This baby can tune in all sorts of inter seek that permits the search scan mode to 137 86 MHz you might find activity esting things too In addition to the stan operate at the scanner s special 50 chan there In fact put your scanner into search scan mode and let it run through the 136 to 138 MHz portion of the spec trum and you might discover signals from any of the many space trinkets operating there Don t expect to hear conversations though You ll either hear an open car rier that is no modulation at all or else you ll hear radiotelemetering data sig nals Those satellites can be heard when they are triggered into activity by com mand signals from their associated ground stations And you ll of course hear only those satellites that are in line
133. ct Note that there are two kinds of triac s two mode and four mode The four mode device can have its main terminals in any order with respect to the gate while two mode units won t operate with their main termi nals reversed Be sure to check the data sheet before soldering into position Usually triacs have their gates referenced to the main terminal MTI and all conduct when the voltage between MTI and the gate reaches about 0 9 to 1 4 volts positive or negative depending on whether the triac operates in quad N r D ez L Fig 2 The basic circuit of Fig 1 can be upgraded as shown here by the addition of a 3 position center off switch and neon lamp with a self contained bias resistor MT2 QUADRANT II QUADRANT I Vur2MT1 79 Vur2uT1 70 Vewur lt 0 Vemt1 79 Leg i V A i d MT2MTI MT2MTI or t ae Ier Ter ax T VMT2MT1 LA VGMT1 56 1 Vur2urT1 lt 0 Vurauri lt 0 Vemm lt 0 Veur 20 QUADRANT Ill QUADRANT IV MIZ Fig 3 Usually triacs have their gates referenced to the main terminal MT1 and all conduct when the voltage between MT1 and the gate reaches about 0 9 to 1 4 volts positive or negative depending on whether the triac operates in quadrant or quadrant Ill respectively Four mode triacs also operate in two additional quadrants quadrant Il and quadrant IV rant or quadrant HI respectively Four mode triacs also operate in two additional quadrants quad
134. ctalioadi Pim Canu s Operating Terngaveture Range i ei Capacity Range 1 Di SA e d Ternearature Coefficient 3 Watt Remetor Anoortementa d Stender Camecrry Tolgrence Dieespetion Femo mg ASIa g ua D on 19 t Inetatnon Reaestance 1C IO 4 1 t Vonage Cosffictanc IDE Ney iy j bes DIE om 9 Agne ew c 070 NEC Memory Chips a Decided Miuliyet fum Doscepdion 1 AMP SILICON RECTIFIERS S c GT 2 DE Core e n ANM 5 p Dy Ge x i 3 Wrewou H Resistors Water Ys 3 1 h Araeta inb EA Wai li 4 v 8t A 53 Di Signetice 6 uaa SSESR 88555 44 204 M 45 0 NCN j JA ST MC 148 FN 4116 200 nsec 16 30421D R TASON MAC Teun AN Pree Pe Pa OF 741 SIIN 741 SZIN ESO iN d x n m Hu S205 MESOZOA a ha 27N NESOIAE E 3 4t SJON NE SCLIN ML SION Mom Fac SI J4 S WM 4t 540 al SAIN Mi Sein MLSSIN FOL SAN 44 585 a STIN PALSTAN 4 8 75N 74 SAN 14 5 B 44 SDA 44 SABA 74 SOEN 34 SON aL SRN Ja N Ja 509N 74 2N Mi y Fak Sv lan LW EA 298 4 ToN 4L 26h 144 AA CA HS W 582 gt SOTECECE SE evzegsuer d Ltr RSbSRRRs SZ amp 5 amp 689 3 t5t v tlm EI ES EEREX JZEZE Lr Opt are Temp Henge 74C 18 4 ac 154 Szze B Rote WC 18 794 PAC POON 74C HI 0 74 VIN FS LR ES ERERSSESS bad w De 10 19D 6 NEC Microprocessor Chips ru I gt 290 7400 3000 Tuy er j 5 gt 12 Po 0000 Pert Me Oeecnptto
135. ctronics back issues 1985 4 25 Jan Feb 85 not available Write in issues desired To order any of the items indicated above check off the ones you want Complete the order form below include your payment check or money order DO NOT SEND CASH and mail to Hands on Electronics Reprint De partment P O Box 4079 Farmingdale NY 11735 Please allow 4 6 weeks for delivery The pointer indicates one of several sets of jumper pins used to program the controller for specific drive characteristics The controller usually comes with a data sheet that gives the jumper setting for most drive models REPRINT BOOKSTORE CJ 104 Radio Electronics back issues 1984 5 25 Jan Feb Dec 1984 issue is not available Write in issues desired 1 C 103 Radio Electronics back issues 1983 5 75 Jan Feb May August are not available Write in issues desired 102 Radio Electronics back issues 1982 6 50 Jan Feb May Dec is not available Write in issues desired EE C 101 Radio Electronics back issues 1981 7 00 Issues available July Aug Sept Nov Write in issues desired O EH87 Experimenters Handbook 3 95 O 154 How to Repair VHS 3 50 O 155 IBM Typewriter to Computer 3 00 O 125 Radio Electronics Annual 1985 3 50 O 126 Radio Electronics Annual 1986 2 50 156 How to Make PC Boards 2 00 O 157 All About K
136. cts the early 1920 s ACK IN THE EARLY DAYS OF RADIO THE VACUUM TUBE was king of the regenerative circuits Any replica of a golden oldie should have visible one or more vacuum tubes pouring out heat from a red glowing filament Although the project described in this article Grandpa s Antique Ra dio may appear as a two tuber it actually performs by using solid state devices The vacuum tubes are there just for show The regenerative regen circuit used in the radio is very old but the radio operates with modern day FET transistors and a single audio integrated circuit chip A combination of the old and the new bring back the antique radio of yesterday The Circuitry The FET transistors QI and Q2 and the LM386 low voltage audio amplifier U1 provide comfortable earphone reception refer to Fig 1 Transistor QI comprises a broad band RF amplifier and isolation transistor Besides amplify ing the weak broadcast signals picked up by the antenna the RF amplifier isolates the regeneration circuit preventing RF noise from radiating directly into the antenna The RF signal is transformer coupled via LI L to the regeneration circuit Coils LI and L2 interact mutually as a transtormer and incorporate a ferrite core to raise the circuit s Q ee Radios On the Cover One of the radios en the cover is not the antique it appears to be but a replica we II tell you which one it is a little further down However th
137. d the dis play had to be interpreted as either the time mode or the day and date mode important in that this would determine which sequence of button pushing was to be followed to set each Continued on page 9 HANDS ON ELECTRONICS 4 Page 8 GADGET OCTOBER 1987 en WATER WATCHES Cont from p 8 of the instrument s five functions With at least one watch what came up on the display didn t resemble any thing the instructions had indicated We attributed this phenomenon to in sufficient current and went back to dunking dousing and showering the watch and its stubbornly dry sponge It wasn t until after the numerals 18 88 appeared on one display that we found out that this indicated over voltage i e too much aqua pura Luckily no damage was done but the problem can also be triggered by in troducing certain liquids other than water into the Water Watch Our second major peeve about these otherwise fun timepieces is exclusively an aspect of its modern technology Since these are relatively simple digital instruments adjusted and set with just two buttons or pins the sequential set ting of functions drove us to distrac tion Maybe a mistake was working with several very similar watches at the same PROTON Cont from p 5 note If your VCR image is fuzzy it s probably because your equipment isn t good enough to use with the Pro ton 625 The cause of
138. d Band Radio The third edition of the book is just out some 400 pages of information A big part of the RDI publication is its computer generated graphic presentation of the shortwave frequencies showing sta tions frequencies and daily schedules based on actual worldwide monitoring The graphic data also tells you the major languages being aired and when the sta tion s power and much more In addition you will find RDI s expert reviews of shortwave receivers accesso ries and antennas plus feature articles Radio Database International s new book is available from many shortwave radio dealers around the world for 14 95 or from the publisher RDI Box 300 Penn s Park PA 18943 for an additional 1 95 shipping and handling charge Weather Over There J N M Legate areader in Glovertown eg M Newfoundland Canada says that SWL s planning a trip to Europe might be inter ested in the sort of weather they can expect before they depart If a listener has a receiver that can tune in sideband signals he says Shannon Airmet is received quite well in Newfoundland and may be heard in the USA too The aeronautical transmissions from Ireland s big international airport offer regular weather reports Reception is vari able but not often inaudible with 5 640 and 8 957 kHz being the best during daylight hours and 3 413 kHz at night Sometimes he adds 13 264 kHz is good fo
139. d address and zip code Your new ad dress and Zip code r i i i i i i i i i i L name 8 please print address Sum city B state zip code Maii to Hands on Electronics SUBSCRIPTION DEPT P O BOX 338 Mt Morris IL 61054 9932 2861 H38O0100 N m HANDS ON ELECTRONICS N eo By Marc Saxon SCANNER TECHNOLOGY SEEMS TO BE includes services such as Cellular Mobile supply and mobile mount The set is tag producing some healthy competition be Telephones ged at 499 95 tween manufacturers each trying to outdo It s a snap to program the Turbo Scan Complete details are available from Re one another with super scanners offering 800 and it lets you carry out that task via gency Electronics 7707 Records Street all sorts of fancy features This month we its translucent rubber keypad that s back Indianapolis IN 46226 That space re just have to look at the scanner that Regen lit for nighttime use and a dual level vac search band by the way is an interesting cy Electronics says is their latest entry in uum fluorescent display Frequencies can feature It offers you the chance to tune in the sweepstakes be entered randomly into any of the scan artificial satellites many of which operate They re tossing around words like ut ner s 75 channels or grouped into any of just above 136 MHz timate scanner so you know that the six scanning banks for quicker and If you have
140. d in formation to Marc Saxon Saxon On Scanners Hands On Electronics 500 B Bi County Blvd Farmingdale NY 1735 H NRI s At Home Training in Electronic Design Technology Can Put You in a High Paying Career as an In Demand Design Technician The best jobs in electronics today go to the electronics you can succeed with NRI training people who have the skills to think and work You start with the basics creatively Conceive and design circuits and then rapidly build on equipment Initiate ideas and carry them them to master advanced through Now NRI can help you be one of electronics concepts these people design technicians who NRI Circuit Designer command up to 22 000 as starting salaries cana 3 0 orsa Where cra Gives You Invaluable Hands NRI s Electronic Design Techonology On Experience course starts you with the fundamentals and The hear of your lab training is the builds from there to prepare you for an exclusive NRI Circuit Designer you build electronics career with real growth potenual It s a totally unique instrument with full breadboarding capability built in multiple No Previous Experience Necessary power A K a m a dm Lac Even d you ve never had any generator for circuit testing Fast simple previous training in connections let you create prototype a circuits immediately check them out for funcuon or faults Your Circuit Designer will handle both linear and digital integrated circui
141. d node numbers in consecutive order for proper processing by the program Notice that their polarities have no effect on numbering the same node That concludes our discussion on the rules which must be followed while using ACNAP We now turn our attention to solving a couple of examples using the program Example Circuit Consider the three node network of Fig 3 which has the tollowing characteristics w 100 rad sec V 10 Sin wt 1 5 Cos wt 45 0 5 mhos 0 0067F Fig 3 Even though this circuit Contains both constant current and voltage sources ACNAP eats up the data like a hungry lion Just imagine doing this one by hand According to the rules the first thing to do is give each node a reference number as shown and convert any cosine wave power supply devices to a sinewave reference l 1 5 Sin wt 45 Below is the listing of ACNAP interaction used to solve the circuit of Fig 3 Please note that for resistors conduc tors Capacitors and inductors it does not matter which node is considered the INITIAL NODE and which is the EL NAL NODE Enter the number of nodes in the circuit not counting the ground nade l 25 3 Do you want to enter the frequency in Hertz or 2 Radians second Your choice 2 Frequency RAD SEC 100 Enter number of resistors se e se se ses ses RESISTOR Iesse se see INITIAL NODE 2 FINAL NODE 0 VALUE Ohms 3 Enter number of cond
142. d out at me as the set came to lite Instead of the familiar Channel 5 WTTG lest pattern there was an untamiliar sta tion on the air witha C callsign Letter ing underneath the call letters on that Strange pattern indicated that the station was located in Halifax Nova Scotia more than a 1200 miles away The call crackling out of the speakers of 40 police cruisers was dramatic and frightening officer in trouble and needs help A gun battle erupted during a bank robbery in the 8200 block of Main Street More than three dozen police cars wheel ed into action only to come to a halt at the County Line at 6600 Main there was no 8200 block of Main and the name ot the bank being robbed was unfamiliar to local police Investigation revealed that the bank and 8200 Main were down in Texas 900 miles away That Texas police depart ment used the same 38 MHz frequency as our local police department If you are a ham operator then the source of those incidents is obvious the radio propagation phenomena called skip Because hams use radiowaves to communicate it is vital that hams under stand radio propagation Whether you use low HF 160 and 75 80 meters high HF 40 10 meters or VHF UHF above 30 MHZ there are critical aspects to radio communications that must be understood to properly use your radio equipment In this and the next few editions of this col umn well take a quick look a
143. d subroutines that the reader de velops The routines are for all MS DOS com puters IBM PC JR XT AT Tandy 1000 1200 2000 3000 TI Professional Com ASSEMBLY LANGUAGE SUBROUTINES FOR MS DOS COMPUTERS LEQ j SCANLON CIRCLE 54 ON FREE INFORMATION CARD paq and any IBM compatible computer Saving the programmer from having to constantly reinvent the wheel when creat ing assembly language code this out standing reference gives the computer EARN YOUR B S E E DEGREE THROUGH HOME STUDY Our New and Highly Effective Advanced Place ment Program for experienced Electronic Tech nicians grants credit for previous Schooling and Professional Experience and can greatly re duce the time required to complete Program and reach graduation No residence schooling re quired for qualified Electronic Technicians Through this Special Program you can pull all of the loose ends of your electronics background together and earn your B S E E Degree Up grade your status and pay to the Engineering Level Advance Rapidly Many finish in 12 months or less Students and graduates in all 50 States and throughout the World Established Over 40 Years Write for free Descriptive Lit erature COOK S INSTITUTE OF ELECTRONICS ENGINEERING 347 RAYMOND ROAD 09 GRENG JACKSON MISSISSIPP 72209 CIRCLE 7 ON FREE INFORMATION CARD AMAZING SCIENTIFIC amp ELECTRONIC PRODUCTS PLANS Bag Yourself Au Par
144. dent current sources ICS IVS s supply a positive current to the node connected to the point of the IVS while they supply a negative current to the node connected to the tail of the IVS An example should help to clarify all of that Let s write the node equations for the two node DC circuit of Fig 7 We will then enter the equations into an augmented matrix For node l we can write V Mall t ohm V V 2 t ohm 0 Multiplying by 2 and realizing that V 0 we get 3V V 0 Eq 5 Following the same steps for the KCL equation at node 2 gives V V2 ohm V V6 ohm 4 ep ONT Vx VA 3 Fig 6 When analyzing the nodes connected to a voltage dependent current source nodes 1 and 2 the nodes it s dependent on nodes 3 and 4 must be solved for first Fig 7 Going through the trouble of setting up an augmented matrix and going through the math for a circuit as simple as this would be a waste of time for a human Of 3V 4V 24 Eq 6 Those two KCL equations Eq 5 and Eq 6 would be entered into an augmented matrix as follows 3 I d 3 4 24 Because ACNAP must deal with complex numbers to per form AC network analysis its augmented matrix is not just two dimensional as is the one shown above ACNAP uses a three dimensional matrix the A matrix The third dimen sion allows ACNAP to distinguish between the real and imagi nary portions of complex numbers T
145. des of electrical trouble brownouts as well as blackouts Read some more In addition to offering complete protec tion against power failures the BC 325 features full brown out protection and a built in filtering network that guards your equipment against transient spikes and line noise whenever it s operating on AC power The BC 325 is a complete system that includes a maintenance free gel cell bat tery regulated battery charger alarm with reset and is housed in a cabinet that will fit into any environment No installation is required just plug it in With its 26 bee i i Le CIRCLE 60 ON FREE INFORMATION CARD ampere hour battery the BC 325 supplies 60 minutes of emergency power at half load and 25 minutes at full load allowing for the safe comfortable shutdown of a computer system The suggested retail price is 479 00 For additional information contact Tripp Lite 500 North Orleans Chicago IL 60610 Tel 312 329 1777 Computer with Software A computer without software is like a car without a battery useless That s why Vendex Pacific Inc has bundled five CIRCLE 62 ON FREE INFORMATION CARD of the most frequently requested software packages with every new Vendex Tur bo 888 XT computer allowing the user to be up and running in literally a matter of minutes The Vendex Turbo 888 XT comes to the user complete with 512K RAM a col lection of discount coupons worth over 1 800 344 4539 AK
146. e 611 Fifth Ave New York NY 10012 But maybe that s why the radio s instructions spell the word Switch with a dollar sign Price 39 As part of the battle to establish itself in the U S consumer market the fiesty South Korean company Samsung Electronics America 301 Mayhill St Saddle Brook NJ 07662 has just introduced its first Hi Fi Stereo VCR with MTS decoder VR6600F The front loading unit offers two video heads with HQ circuitry stereo audio recording and playback 110 channel cable compatible a step beyond cable ready we guess fre quency synthesized tuning and a built in MTS stereo decoder for reception of stereo TV broadcasts Other features include a 14 day six event programmable timer three speed record and playback auto still release auto rewind picture search pause still and convenient one touch recording The unit s wireless remote control has 20 keys and 23 functions including direct access tuning channel up and down and pic ture search in all three VCR playback speeds Price 649 95 The company behind the very popular Teddy Ruxpin talking bear is branching out in its attempt to market electronic products aimed at kids One new product from Worlds of Wonder Inc 4209 Technology Dr Fremont CA 94538 is called Wondervision and besides being the future of kids entertainment it s also the only modular audio video entertainment system designed just for kids
147. e bass CDs can produce Of course strong bass can be achieved by adjusting a player s tone control or equalizer but those methods tend to muffle the music Whatever Panasonic s innova tion it was achieved without any nega tive effects on the over all audio qual ity Sony was first with an enhanced bass system introducing its DD 00 Boodo Khan Stereo Cassette Player last year But Panasonic has gone that player one better with an auto reverse fea ture something missing from the Sony unit as well as incorporating an AM FM tuner into the RX SA 20 Innova tion may receive the acclaim but intel ligent catch up demonstrates market ing smarts on the part of Panasonic The firm also unveiled a portable stereo system with dual tape decks and a CD player the RX CD100 which also features XBS The retail price for this unit has yet to be announced while the Panasonic RX SA79 carries a suggested retail tag of 159 95 Panasonic however doesn t have a monopoly on enhanced bass Featured at the CES s annual Design and Engi neering Exhibit a room devoted to the electronics industry s most distin guished achievements was a new portable system from JVC Company of America 41 Slater Drive Elmwood Park NJ 07407 Ranked 80th among the 227 noteworthy products on dis play the JVC PC V2 includes a tape deck CD player AM FM and short wave radio reception JVC calls its enhancement system hyper bass sound Of
148. e impressive looking Sonora at the bottom of ahe cover is the real thing It dates back to 1944 which makes it one of the few radios manufactured during World War Two At that time the countrys efforts tumed from audio which is said to calm the savage breast to making war noises said to be the great equalizer no pun intended That model was created in an effort to bolster up the civilian population s moral Next up on the totem pole is a General Electric model also authentic manufactured in 1948 making it a post war item At that time alf of the entertainment industries enjoyed great patronage not excluding radio Even though many such models were sold they are hard to come by which makes them very valuable Taking things back a track is the radio above that a Halicrafters Model S 38B from 1938 The unusual thins about that consumer baby is its metal cabinet but that s Halicrafters style Now we come to the trickster in the group the reproduced Thomas Model BD109 To look at it is to be taken in hook line and sinker That little beauty carries a suggested retail of 79 95 not bad if you re a real antique enthusiast E e ema ema egen engt m g tt pot DRAIN SOURCE DATE BOTTOM VIEW R4 50K EARPHONE E e EARPHONES war cA Fig 1 Here is the schematic diagram of Grandpa s Antique Radio It contains a regeneration circuit and modern solid state devices
149. e lead out should run along the line of the other over lapped end of the former 1 e the two inner edges of the cable should finish 20 mm apart Bind the end of the winding with two layers of tape and leave the same length of lead out as at the start 50 mm Once that has been done tape the cable at the top and sides of the former With the loop now completed it should be clamped onto the top of the control housing using the right angle clamp supplied with the kit Adjust the position of the coil so that the two lead outs run centrally through the PCB connector housings Next position a ruler against the front of the connectors and draw a line across both cable lead outs with a ballpoint pen Remove the coil from the housing and cut the cable carefully along the lines The 16 way cable connectors can now be fitted to the leadouts To do this locate the connectors over the cable with the key way the raised section towards the front of the coil With approximately 2 mm of the cable end protruding from In this top view of the assembled PCB notice that the battery is wrapped in foam rubber That is to insulate it from other components thus preventing shorts the connectors apply pressure using a pair of multigrips or similar until the connector is fully closed The unit is now ready to be tested Connection to the Receiver If your receiver has a 50 75 ohm coaxial input then a cable between the two is all that is needed A coa
150. e modification shown in Fig 7 may be used The load current equation for the non inverting version remains unchanged except for the polarity ll Vid Ri Voltage to current converters are easy to experiment with Just connect a milliammeter across the output and watch what happens as the input voltage is varied You might also want to try using various resistor values for R1 For a practi cal circuit just use the equation to find a suitable resistance value for the desired input and output ranges which is calcu lated from R Vill You can also experiment with variable load resistances R Connect a resistor or potentiometer in series with the meter to raise the load resistance or in parallel with the meter to lower it PARTS LIST FOR THE POLARITY SPLITTER Q1 TIP3055 or similar NPN silicon transistor see text Q2 MPS2907 or similar PNP silicon transistor see text R1 R2 1200 ohm 4 watt 596 resistor R3 R4 4700 ohm 4 watt 5 resistor U1 741 op amp or similar integrated circuit Constant Current Source Some circuit applications require a reference current that does not change with fluctuations in the load Again the op amp comes into play By slightly modifying the basic voltage to current converter circuit we can create a constant current source as shown in Fig 8 Fig 8 4A constant cur rent circuit is produced by slightly modifying the basic voltage to current converter The
151. e ook ok ci ck ck e ok eoo ck ok ce opc ci oe oe ce zo ck ck oft ok oko c c ce ck ACNAP AC Network Analysis Program c 1987 by James E Tarchinski FEK K k k E ECKE SE cE 0E o ko ceo OK HK o obe ok ok oe ck ok ce o iE cb ook oe oe oe oe og k ce e kk Kok ok ook oec e oko cb ok oec CE coke oo IK ok Koo SE CE oh E ck k ok ok oe oe k oco E SER ok K c e kk This program uses Nodal Analysis to determine the node voltages of linear AC networks These networks may range in size from to 25 nodes not counting the ground or datum node Seven types of devices are incorporated in this program Resistors 2 Conductors 3 Capacitors 4 Inductors 5 Independent current sources ICS 6 Voltage controlled current sources VCCS 7 Independent voltage sources IVS Press any key AS you can see that screen lists the seven types of compo nents that ACNAP can handle listed in the same order that they will be requested by the program Pressing any key will bring up the next screen an instruction page Five rules must be followed to use the program correctly they are listed on the instruction screen as shown below For all circuits these conventions must be followed l All nodes of the circuit must be labeled with consecu tive integers 1 2 3 etc 2 The ground node must be Node O 3 The ground node ts not counted when determining the number of nodes m a circuit 4 For power supply elements current
152. e standard compact typewriter and retails for 1 000 Remember when electric pianos made their first appearance on the market First Casio made tiny elec tronic music machines which eventu ally evolved into the sophisticated syn thesizers found in nearly every high grade studio and many rock bands Suzuki P O Box 261030 San Diego CA 92126 may have started down the same road with guitars The UniSynth is an electronic guitar Not an electric instrument but one which synthesizes the music it pro duces The instrument can play in six different digital voices including guitar I II synth vibes I II and brass It creates its own rhythms and can do auto chord play for non guitarists The UniSynth features metal Strings between two bridges for strum ming or picking and plastic buttons along the instrument s neck a differ Sharp Eisi Mate Calculator ent button for each fret Perhaps the outstanding novelty of the entire CES was The Levitator manufactured by United Imports amp Manufacturing 6846 Pacific St Continued on page 9 GADGET Page 7 2861 H380120 LD G3 Aquatic Time THE WATER WATCH 300 BBU Manufactured by VentuResearch 1539 Vanderbilt Dr El Paso TX 79935 Price 24 HO WATCH Distributed by Admag ination Inc 39 W 32nd St Suite 801 New York NY 10001 Price 25 A gentleman we once knew had a thesis regarding what he called ab
153. e using subdirectories Using Referee to manually control your programs 1 Boot up your PC but don t ioad any resident programs 2 Move to the subdirectory that contains Referee s files and type at the DOS prompt to load Referee s core program into memory 3 Load the rest of your RAM resident programs 4 Type statement contains that subdirectory at the DOS prompt You don t need to be in the subdirectory that contains Referee Just be certain that your PATH RAM resident programs you are planning to use Use the third menu Specify Applica tions and Their RAM Teams to enter the names of any application programs you plan to use and to designate which RAM resident programs you want active inac tive or not change with each application program Now exit to DOS As you access each application pro gram Referee will automatically activate and deactivate the RAM resident pro grams according to the RAM Team spec ified for that application What You Get For the purchase price of 69 95 you teams to watch out for and Sideline Reter ee a RAM resident option which allows you to enter Referee to make changes from within an applications program You are provided detailed information about your system Referee tells you how many programs are loaded into memory whether they are active or inactive how much memory is used for each and how much memory is still available You can also use Referee to unload programs fro
154. eased or decreased PARTS LIST FOR THE DUAL POLARITY VOLTAGE REGULATOR D1 9 1 volt Zener diode Q1 TIP3055 or similar NPN silicon transistor see text Q2 MPS2907 or similar PNP silicon transistor see text R1 12 000 ohm 4 watt 5 resistor R2 R3 1200 ohm s watt 5 resistor R4 R6 10 000 ohm 4 watt 5 resistor R5 R7 2200 ohm 4 watt 5 resistor U1 U2 741 op amp or similar integrated circuit for any reason Ul s output signal changes altering the base current to Q1 thereby maintaining a constant voltage source at the desired level With the component values shown in Fig 1 the circuit accepts a positive unregulated input of 18 to 20 volts and provides a well regulated 9 volt output that s capable of supplying up to 100 mA 0 1A without any problems The circuit is not particularly efficient Half of the input voltage is wasted And since the full output current passes through QI it should be selected accordingly Once you have the UNREGULATED REGULATED VOLTAGE Time VOLTAGE IN e J OUT 01 9 1V a Fig 1 in this basic voltage regulator circuit UT a 741 Op amp serves as a reference voltage source set by zener diode D1 and resistor R1 to control drive current to the base of Q1 which is set up in a series pass configuration PARTS LIST FOR THE POSITIVE VOLTAGE REGULATOR D1 9 1 volt 1 watt zener diode Q1 TIP3055 or similar NPN silicon transistor see text R
155. econds for one period so the frequency is f It 1 000628 1592 Hz Don t be concerned if your value is way off There are many variables in the circuit to throw it off 9V R1 R 1K 100K 100K R2 7 V2 9y 12K D 22K L Fig 18 This summer can actually add two voltages together as long as their sum is less than the supply voltage The output shouid equal their sum since no gain is provided A Mixer Circuit 23 Remove power temporarily and add the circuit in Fig 18 to your breadboard Use the second op amp in the second 1458 package Use either the 1 000 ohm or 10 000 ohm potentiometer for one input depending upon which potenti ometer you did not use in the Wein bridge circuit That is an op amp summer with negative DC input voltages 24 Apply power to the circuit Set the potentiometer so that the voltage between ground and its arm V is 2 volts Measure the value of V at the junction of the 12 000 ohm and 22 000 ohm resistors Record it below V volts E 25 Now measure the output at pin 7 Write your value below Vo volts 26 Using the values for V and V you measured in Step 24 compute the output voltage using the summer formula given earlier Write in the output you calculate below Vo 8 volts How does it compare with your measured value Steps 23 26 Revisited The circuit you built is a two input summer Since the input and feedback resistors are all equal 100 000 ohm the gai
156. ectronics Series puts you into the electronic picture one easy step at a time Fifteen MASTER THE NEW ELECTRONICS WITH McGRAW HILL S unique Concept Modules sent to you Pe one every 4 6 weeks give you a handle on subjects like optoelec tronics robotics integrated circuits lasers fiber optics and more Each Concept Module goes right to the heart of the matter You waste no time on extraneous material or outdated history It sa fast efficient and lively learning experience a non traditional approach to the most modern of subject matter Unique Interactive Instruction With each module you receive a McGraw Hill Action Audio Cassette Each tape is a dynamic discussion that drives home the key facts about the subject Your learning With your first module you i get this a solderless breadboarding system You ll use it through out the series to build elec tronic circuits and bring concepts to life experience is reinforced through interaction with vividly illustrated text audio cassettes and actual electronic experiments Indexed binders preserve backup material notes and tapes for convenient referral s Experiments in Contemporary Electronics Throughout your series lab oratory experiments reinforce every significant point This essential experience dynamic hands on demonstrations of theory in practice will help you master principles that apply all Au the
157. ed 15 00 200 free ca pacitors diodes with each 45 00 order All parts good Add 59e S amp H 1 50 minimum Send check or money order to CIRRUS ELECTRONICS 1805 Oak St Paso Robles CA 93446 CABLE TV converters Scientific Atlanta Jerrold Oak Zenith Hamlin Many others New VIDEO HOPPER The copy killer Visa M C amp Amex ac cepted Tol free 1 800 826 7623 B amp B INC 10517 Upton Circle Bloomington MN 55431 2000 tubes 50 cents each Also have IC s 677 West Ave H 8 Lancaster CA 93534 Phone 805 945 5087 FIBER optic cable 10FT 8 50 100 dia 100F T 69 00 JSDIST POB 361 Parchment MI 49004 DO IT YOURSELF TV REPAIR NEW Repair any TV easy An Write RESEARCH Rt 3 Box 601 99114 ne can do it R Colville WA TUBES 2000 TYPES DISCOUNT PRICES Early hard to find and modern tubes Also transformers capacitors and parts for tube equipment Send 2 00 for 20 page wholesale catalog ANTIQUE ELECTRONIC SUPPLY 688 W First St e Tempe AZ 85281 602 894 9503 MASTERCARD AND VISA are now accepted for payment of your advertising Simply complete the form on this page of the Market Center and we will bill you BUY BONDS ADVERTISING INDEX HANDS ON ELECTRONICS magazine does not assume any responsibility for errors that may appear in the index below Free Information No Page 13 AMC Sales coo e 17 5 All Electronic 3
158. ed op amp circuit is the inverter as shown in Fig 4 It consists of a feedback resistor R that connects the output back to the inverting input The input signal is applied to the input resistor R The non inverting input is grounded With that connection the gain of the circuit is set entirely by the external resistors The gain value is simply the ratio of the feedback resistor to the input resistor R R With the values shown in Fig 4 the gain is 100 000 10 000 10 In other words that circuit multiplies any input signal AC or DC by 10 and inverts it f 2 volts is applied to the input the op amp will produce a 20 volts output A non inverting amplifier is shown in Fig 5 The connec tions are almost similar except that the input resistor is grounded while the input signal is applied to the non invert ing input Again the gain is a function of the feedback and input resistors and can easily be computed with the simple Fig 4 The inverting amplifier requires a feedback resistor at the inverting input to channel some of the output back That cancels some of the input signal cutting down the gain If one is not used the output swings wildly Fig 5 The non inverting amplifier requires a feedback resistor at its inverting input but it accepts input at its non inverting input and outputs an in phase signal expression Gain Rj R Therefore the output voltage is Vo ViA R Rj With the values gi
159. een nny FREER REREREEEEE REY EY EEE EY V 3I M a 253S QVu AouenbedJa LNAdNI N3HI Z SuIdeZ M J n 2a319eH Aouenbeig LndNI N3HL I vg JI LNINd 0991 OLO9 dead N3HL Z lt HOT gt JI Y a 1397042 INO L ndNI 4 PuOD2es suerpeNH E a LNIMNd 4 JO Z23419H Io LNIMNd vty Aouenbe1j equ3 2eiue O3 JULM noA oq LNIMNd DEZ OzEZ OTEC OOEZ 0622 0872 OL72 0972 CL Otzz HESE 0772 OTZ 0022 DA ostz OLT2 0912 OS Tz OPIc OE TZ oziz OTT2 ooTz 0602 0802 OLOC 0902 osoz otoz ocoz ozoz otoz 0002 0661 0861 OL6T 0961 OS6T OP61 O 61 0261 OT6T 0061 0681 0881 DCS 0981 oset DLC DEST ozet OTST 0081 0641 0841 OLLI 0941 OSLT OPLT DEI O2 L1 OTLT 0041 0691 GEN oLSt 0191 OLOD 43 PUL al 92 TI N N3HL T gt N YO SZ lt N JI Z 1 epou punoaIb ai Butjyunod you LNdNI ui HZEMNDN GITWA V NH3LN3 3SWM33d LNIYd N u OCTOBER 1987 LNIHd IN uw IFMNOATS eQ3 UT sepou jo Joequnu eui 1e51U3 LNINd O6ST OLOS N3HL O ST OLOS NS3Hl IE OT HOTOD Aan Aue sseld LNIBNd L YOTOD vw 0 9epPoN epou punoa equj BUTfyYuNnos you u 4 9pPOU eues oui o3 pe35euuc2 q Aew AI Se2inos Ssb EXTOA om3 ON Eu ER ul o8L 972 313 NIS 9S Z I VW ST 4 WIOZF BYQ UT ag Asnw Zaui er e pesn aq 3snu sejeuTploo2 1eq od pue e2uoelo0jel oAPM oUTS L D eo1nos abeitoa e2ipnoe 3q3uel4Jn2 syuawete Aiddns 1ewod IOJ E 4 3Tn21T2 e UT Sopou jo 2 4 19qunu equ
160. el 1036 is available in kit form with step by step instructions for 69 95 or assembled and tested for 99 95 For green LED s model 1036G add 10 00 For more information contact NRG Electronics PO Box 24138 Fort Lauder dale FL 33307 Tel 305 971 3823 Radio Cassette Recorder CD Player They ve finally created a stereo radio cassette player with a built in compact disc player And the player offers the FF 1 fine focus single beam laser pickup Other features include 5 step random ac cess programmability skip and search CIRCLE 71 ON FREE INFORMATION CARD functions a repeat key and a comprehen sive LCD display The cassette deck section operated via soft touch controls offers auto reverse in playback and record modes a Dolby NR system and a reverse mode selector The selector allows the user to listen to just one side playback one side followed by the other side or repeated playback alternating from one side to the other Cue and review controls a pause con trol and a soft eject system are included in the tape section as is a metal play back CrO normal tape selector The RX FD80 offers improved sound dispersion from the two way four speaker system The speakers at either end of the unit each boast 54 in PM woofers with Y in tweeters Ambience stereo the feeling of hav ing sound widely dispersed around the room is created when a portion of the total sound is momentarily delayed and cross fed
161. electronic feats So for some really great electronics reading get your copy now How Send us your favorite circuit along with application an in depth de scription of how it works and an easy to read schematic Please limit the circuit to no more than two transistors or IC s be cause space is limited When we OK it we will send you a copy of the F PS book Turntable Amplifier My wife and I are recently married and a surplus of money isn t one of the many problems facing this newly wed cou ple However did manage to save a few pennies out of my lunch money so that on her birthday was able to buy her an excellent and expensive turntable com plete with tone arm and stylus Being a music lover she was thrilled and I ex plained that when we could afford it we d get her an amplifier and a speaker system that this was just the start came home the next evening to see her crouched over the turntable listening to the stylus tracking in a record groove I went to my basement workshop after din ner and quickly put together a pair of the amplifiers Of course they aren t super quality so the big names in audio need not fear competition from this humble hobbyist but they did let my wife actu ally hear the music Sam Merchant Ocean Beach CA Fig 1 The input signal is fed to the inverting input of U1 a 741 op amp set up as an amplifier buffer Ut s output is fed to the common base leads of Q1 and Q2
162. er the direction of Editors Eric Teicholz and Joel N Orr more than 20 specialists in the field have contributed significant material on their areas of ex pertise They tell exactly what must be done to convert today s workplace into the factory of the future emphasizing the economics and the specifics of CIM The Computer Integrated Manufactur ing Handbook shows how to utilize CIM technology by exploring the technologies and methodologies involved by describ ing the obstacles to be overcome when CIM programs are started in typical indus trial situations and by examining the im plementation issues to be considered This authoritative resource investigates a wide range of important aspects from the role of CAD CAM in CIM to numer ical control systems from a concise over view of the CIM industry to a projection of future trends and developments Full discussions deal with such topics as group technology robotics process planning art ST e e a 7 ON FREE INFORMATION CARD production planning and control the role of materials handling technology man agement and factory automation plan ning for a competitive CIM environment and the considerations of controls feed back and benchmarking for successful implementation The Computer Integrated Manufactur ing Handbook contains 466 pages and costs 59 95 from McGraw Hill 1221 Avenue of the Americas New York NY 10020 Circuit Design for Electronic instrument
163. ertain the network you enter doesn t contain any inductors or the program will generate a division by zero error in line 2340 The next seven sections of the program load the network description into the computer one element at a time Com ponents are entered in the following order resistors con ductors capacitors inductors independent current sources ICS voltage controlled current sources VCCS and fi nally independent voltage sources IVS Each of those seven sections have the same basic design They begin by asking for the number of components of 4 particular type The number of resistors for example is input on line 1790 If the number of components the vari able NC in the program is less than one the program skips ahead to consider the next type of component If NC is not less than one the program uses a FOR NEXT loop to enter the components one at a time and to load them into the A matrix More information on A matrix is given in the Tech nical Notes section of this article Two subroutines are used to enter the component data Input Subroutine 1 begins on line 3240 and is used to enter RL H3HOIOO HANDS ON ELECTRONICS P e j ENTER fr FREOUENC 16 d n DIN CIRCUIT CONDUCTORS E d fe i H p E d NU P i 3 the value and the node connections of resistors conductors capacitors and inductors Beginning on line 3870 Input Subroutine 2 is used for the power supply d
164. es If you give it an input signal it will tell you the area of the curve defined by the input signal More On Comparators To understand the operation of a comparator it is first necessary to understand the output characteristics of an op amp The output of the op amp has voltage swing limits that are equal to approximately a half of a volt less than the values V N Cen REFERENCE o Fig 9 A comparator is nothing more than an op amp with its gain wide open Since it has no feedback resistor the output swings between the power supply voltages of the supply voltages For example with 9 volt power supplies the output voltage swing is limited to roughly x 8 5 volts Any signal that attempts to drive the amplifier beyond those points will simply cause the amplifier to satu rate and clip For that reason the gains of the circuits dis cussed previously must all be such that with the input signals provided that the saturation limits are not reached The op amp when used as a comparator takes advantage of those two large positive and negative voltage swings The output is essentially binary in nature for a comparator One saturation level will be the binary 0 while the other will be the binary In that way the output can signal when one input 2861 H38O100 E I HANDS ON ELECTRONICS co Js signal is larger or smaller than the other The two inputs to a comparator are the reference as marked and the input signa
165. es and wipe off the excess paint Glue the dial in place See photos The unique dial knob assembly was constructed of brass plated lid support or a flat piece of brass See Fig 4 Grind off the hinged support and put a black knob in its place Select a knob with a brass insert and screw Break and re move the plastic area of the knob Ep oxy the brass insert to the plated brass piece Grind down the end piece to a sharp point Now fasten the dial assem bly to the shaft of the variable capacitor with the small knob screw Not only is Grandpa s Antique Radio easy to build its just plain fun with the added twist of the good old davs some sixty years ago m HANDS ON ELECTRONICS eo The tubes are dummies in the author s model If you wish you can power up the tubes using a filament transformer and nothing eise The tubes will add color and heat like the old sets Gm em em em em em em em em em XO MO GO GO em em em em HST em em e e see eme m ae Gen Gee Gn Geo s e e Ge Ge me e e aj T BP173 COMPUTER MUSIC PROJECTS 6 95 Shows how to use your home computer fo produce electronic music Many circuits Mostly jar gon iee Secrete el ine COMMOOORE 4 Ae lolroduttion le Programming the ATARI md BP176 TV OXING FOR THE ENTHUSI AST 6 95 Practica authorttative intro to this unusual aspect ol elec trorucs B12 11 in 144 pp Computer Terminology Erpleined 000 800 x4 DN z BE
166. es too much the diodes conduct one on the positive half cycle the other on the negative half cycle That puts the 47 000 ohm resistor in paralle with the feedback resistor thus reducing the gain and lowering the output The diodes cause some clipping distortion The remaining network made up of RI and C produces positive feedback that sustains oscillation When the output 48 5V COMPARATOR OUTPUT PIN 1 INTEGRATOR INPUT PIN 1 Fig 16 The output waves from your home brew function generator should line up like this with the outputs varying between 8 5 and 8 5 volts Note the identical frequency OUTPUT Fig 17 If you can t get the light bulb needed for the circuit in A then you can use the circuit in B Its output will not be as clean but is good enough here is in phase with the input the circuit will oscillate if the circuit gain is high enough The RI C network is a voltage divider so all the output doesn t reach the non inverting input The circuit gain offsets that providing ample input In order for the circuit to oscillate the output must be exactly in phase with the input Because an RC network is used the correct phase will occur at only one frequency That becomes the frequency of oscillation Using the formula given earlier you should have computed a frequency of f 1 6 28 10 000 00000001 f 1592 Hz Your measured value of the period should have been about 628 micros
167. ese liquids contain sugar and other contaminants The last thing we d want to do how ever is pour cold water on th se other wise marvelously simple technological toys What we want is an easier way to pour water into them and a less con fusing way of adjusting and setting their functions If only Count Volta had also thought to invent the digital wristwatch to go with the energy cell which bears his name maybe all these problems could have been solved dur ing the age of reason instead of hounding us in the contemporary age of marketing G A of trash get yourself a TV set Here s where we part company with the Proton cult Maybe Mr and Ms Typical Video Consumer wouldn t de rive any particular benefit from own ing a Proton Perhaps if your audio video system consists of a VCR that s a few years old and cable service the per snickity Proton 625 would be more trou ble than it s worth Of course for the true video lifestyl ist owners of extravagant home enter tainment centers which are residential versions of a video production facil ity the Proton with its multiplicity of input and output capabilities might be a must If we were installing a home studio we d certainly consider a Pro ton but in most other circumstances you might be better off settling for a mass market television G A his or her own private magnetic field The suggested retail price is 99 This is anything b
168. even times in one second The velocity of the wave slows in dense media but in air the speed is so close to the vacuum or free space value of c that the same figures are used for both air and outerspace Propagation Phenomena Because EM waves are waves they be have in a wave like manner Figure 2 illustrates some of the wave property phe nomena ussociated with light and radio waves reflection refraction and diffrac tion All three play roles tn radio propaga tion In fact many propagation cases involve all three in varying combinations Reflection and refraction are shown in Fig 2A Reflection occurs when a wave strikes a denser medium as when a light wave strikes a glass mirror The incident wave shown as a single ray strikes the interface between less dense and more dense mediums at a certain angle of inci dence a and is reflected at exactly the same angle now called the angle of re flection a Because those angles are equal we can often trace a reflected radio or TV signal back to its origin Retraction occurs when the incident wave enters the different density region and thereby undergoes both a velocity and directional change The amount and o LESS OENSE MORE OENSE NOTE o a OEFRACTION ZONE SHADO ZONE d AOVANCING WAVE Fig 2 Reflection refraction and dif fraction all play roles in radio propa gation Reflection A occurs when the incident wave strikes a de
169. everything we examined at CES the PC V2 was by far the best looking new audio prod uct a favorite with us because of its fantastic combination of good design and excellent audio quality The exceptional quality of the JVC hyper bass was amusingly illustrated by an incident in the Design and Engi neering Exhibit When the PC V2 was first turned on its enhanced bass wasn t audible When one of the on lookers accidentally hit the hyper bass control a rather inconspicuous switch the milling crowd was actually hushed by the power and fidelity sud denly evident to everyone s ears The unit s sub woofer is so strong that we could almost feel a breeze coming out of the speaker The PC V2 we think is the first portable system that does jus tice to the superior quality of compact disc audio Perhaps the most publicized innova tion at this year s CES was also the most foolish The largest exhibit booth was devoted to CD Video quite possibly the most idiotic idea to make it to the contemporary high tech con sumer market The CDV is a laser disc which provides no more than five minutes of video and no more than 20 minutes of audio on a standard five inch compact disc A special player is required to play back the CDV which contains basically one music video clip and a few audio selections The mar keting idea is that these will replace the 45 rpm single Judging from the list of participants in CDV software in
170. evices return ing the node connections as well as the real and imaginary components VR and VI respectively of the energy that those devices deliver to the circuit The brains of the entire program is the Gaussian elimi nation routine for complex numbers found on lines 2960 3300 That is the section that solves ACNAP s simultaneous equations to obtain the node voltages of the circuit Note that if the circuit you enter is not valid or if the numbers in the program become too small for ACNAP to handle the Fig 1 Notice the repetitive nature of this flow chart for ACNAP After main data for the circuit is input such as the number of nodes and the frequency the remainder of the program accepts component values and performs algebra error message of line 3110 is displayed ACNAP s solution for a network the node voltages in both rectangular and polar form are displayed in the next section of the program Line 3340 makes certain that only one screen of information is displayed at a time keeping the solutions from rolling off the screen betore you can write them down Finally the last section of code asks if you would like to analyze another circuit Answering with a yes will zero the necessary variables and then return you to line 1600 A no response will end the program on line 3700 A listing of the variables used in ACNAP is given in OPLC ansoo JN OL T I MNOJ T H 3n1MA SEd Tm 3GON IVNIJ
171. exceeding 30 megahytes Warehouses are overflowing with 10 and 20 megabyte hard disk driv es that the business community no longer wants and so they re unloaded at bargain basement prices particularly the 10 megabyte models But t0 or 20 mega bytes is plenty of storage for most small users so il you re willing to settle tor less you can upgrade to a hard disk system for less than the original wholesale cost ol the drive In fact if you can settle for t0 megabytes of storage you can pick up the Microscience model 6 2 drive shown in the photographs one of the best because it has a plated media and automatic head parking for a little more than 100 Actually a basic hard disk system con sists of only the parts shown in the photos a hard disk drive mechanism and its con troller The controller which is usually the halt slot size Western Digital WX see photos or its almost functionally identical full size twin the WX 2 ts A hard disk system consists of a controller and a hard disk drive This pair Why They re Cheap cost less than 100 But notice the drive came without a front panel This half size WX 1 hard disk controller has two smaller header terminal strips which can each drive a disk drive The larger header strip is split by a Y adapter or a two connector cable when using two disk drives HANDS ON ELECTRONICS RO N a drives you
172. expands there are apt to be lags and dis parities between certain market subsec tors pockets of technological resistance that stay stubbornly behind the times In the realm of personal stereo for exam ple the speaker components have re mained steadfastly substandard Along come the speaker specialists Acoustic Research to bring the portable stereo to a state of the art level of per fection What the AR engineers have done is house a 15 watt amplifier in each of a pair of sturdily built two way speak ers fit them each with a volume and bass control and invite you to kick out the jams in your car your campsite or your video system The speakers which weigh in at seven pounds each don t really qualify as portable maybe luggable would be more like it But their black die cast aluminum cases triangular with two corners squared off seem to be hefty Page 4 GADGET enough to take whatever low blows are dealt them in transport The four inch woofer is paired with a one inch tweeter both packed into a sleek breadbox sized unit In a recessed back slot are three power connections AC and DC power input as well as an unswitched AC out let and the RCA type input jack On the front of each unit are the bass and volume controls LED power on indica tor and the on off switch We tested the AR Partners in three configurations car stereo personal stereo and video speaker adjunct For the personal stere
173. f digital gear CES did present some intriguing new gadgets And that after all is what brings us to the semi annual convocation Remember 3 D movies Sega of America Inc 573 Forbes Blvd South San Francisco CA 94080 has introduced two new games for use with home video systems called 3 D Zaxxon and World War 3 D Only 3 D Zaxxon was exhibited but what we saw seemed promising The graphics were nice the anima tion was smooth and the vaunted three dimensional effect accomplished using the same red blue process as 3 D movies and requiring the same kind of special viewing glasses was spectac ular Both 3 D Zaxxon and World War 3 D carry a Suggested retail price of 39 95 Although the CES fashion conscious ness was a little irritating the E si Mate LE 1600 Electronic Calculator from Sharp Electronics Corp Sharp Plaza Mahwah NJ 07430 was genuinely well designed It features 10 digit display performs standard calculator functions and has a built in printer The key board s generous dimensions make use of the LE 1600 comfortable and smooth If you ve been looking for a high resolution dot matrix typewriter which prints in Chinese or Japanese nterna tional Quartz Ltd 24 26 Sze Shan St Yau Tong Hong Kong has what you need The company manufactures a typewriter which prints in both Eng lish and in Chinese and Japanese picto grams some 3 000 plus characters in all The machine is large compared to th
174. four digit LCD with digital clock calendar time and alarm functions Positioned at eye level the remote display unit shows time of day when the scale isn t in use Sharp says its new electronic strain gauge weighing system assures accuracy and eliminates the bother of resetting the unit to zero after each use The PH 430 s most attractive feature at least for the serious dieter is a built in memory which can store four different weights and offers a comparison function that alerts the user to weight loss or gain The dis play alternately flashes previous and present weights along with the legends increase stable or decrease Price 79 95 Announce a new video product and the accessory manufacturers are sure to follow Although prospects for the new CDV combining audio and video on a single compact disc may appear dim Discwasher 4309 Transworld Rd Schiller Park IL 60176 didn t hesitate At this sum mer s CES the firm proudly unveiled its CD Video Disc Cleaner which uses a computer aided design no less to assure a true radial cleaning path so that the entire surface of the CD is covered The CDV Video Disc Cleaner uses a special fluid and non abrasive cleaning pad to safely remove dust and fingerprints from the disc surface Further the fluid is totally safe and will not damage the video disc label or surface p
175. from Ul pin 3 to a small speak er through coupling capacitor C4 and cur rent limiting resistor R4 The complete circuit can be built in a light plastic cabinet with LDRI facing out through a small hole that will only let light in from a single direction Other than that build and use the Wake Up circuit anyway you please And until next month help a friend wake up on time A S Evervtime vou dial vour mother s phone number vou erase last month s inventory 2861 H380120 e HANDS ON ELECTRONICS ao amp VI ELS ac om Reader interactivity continues By Byron G Wels THE MAIL HAS BEEN POURING IN AND the FIPS books have been rolling out Just in case you missed our last column we ve made Think Tank interactive What that means is that from now on vou send in your pet circuit we publish it along with your name city and state and we send you at absolutely no charge a copy of the Collected Works of Mohammed Ulvsses Fips a 12 95 value Back in the 40 s Hugo Gernsback our founder used to write a story for each April issue of Radio Craft Magazine now Radio Electronics Each carried the Fips by line that revealed to regular readers that it was the annual April s Fool Story Because Gernsback was skilled in electronics and wrote con vincingly the stories were not only very humorous but they persuaded many a newcomer into attempting to duplicate those impossible
176. fuse is the voltage and current rating of the fuse It requires good light and a steady hand to read but it is usually there When fuses are discussed the main area of concern is the current rating yet fuses have voltage ratings 32 125 and 250 volts being the most popular ratings What do they mean It s the first number we ran into on the end cap Fuses are sensitive to changes in current not voltage It is not until the fuse element reaches melting temperature and breaks apart that the voltage rating becomes important The element must be able to break apart cleanly and not continue to arc or in the worst case shatter the fuse The voltage rating stamped on the fuse is the maximum volt age at which the fuse can sately do that The actual specification reads for in stance that a 125 volt fuse could safely interrupt a 125 volt 10000 ampere circuit under a short circuit fault condition For tunately most of us do not have the kind of power service to test that specification but the key here is that the fuse used to inter rupt a circuit should have a voltage rating equal to or greater than the voltage of the circuit it is protecting But you say ve seen fuses in the 500 volt supply on my old tube type TV set not very safe since the maximum rated fuse I can get is 250 volts Littlefuse states in their literature For secondary circuit protection where the short circuit current is known to be not more than 50 amperes a
177. g output ground The artificial ground should never be shorted to true ground to prevent serious shock hazard and certainly damage to semiconductors The circuit in Fig 9 requires a regulated input voltage You could use an op amp circuit like the one shown in Fig l or a three terminal voltage regulator Since the input volt age is regulated both halves positive and negative of the output will also be automatically regulated without addi tional circuitry Q1 and Q2 are a pair of complementary opposite polarity but with the same electrical characteristics shunt regulator transistors They create an artificial ground sometimes called a floating ground to be used by the load circuit Resistor R4 ties the inverting input of UI to the artificial ground point The non inverting input is fed a reference voltage set by a voltage divider network consisting of RI and R2 If the artificial ground level shifts for any reason Ul s output becomes more negative than Q2 causing Q2 to conduct more heavily On the other hand if Ul s output becomes more positive QI starts to conduct more heavily When the output is correctly balanced the two transistors should conduct equally The circuit always tries to maintain a balanced condition The transistors should be selected to dissipate a fairly large amount of power For the two output voltages to be symmetrical resistors R1 and R2 should have equal values and R3 should be equal to R4 While most
178. g cost multiplied by number of issues ordered s State Zip WANT TO EXPAND your knowledge of elec tronics Build gadgets that only you can have on your block Acquire a library of projects NEW IDEAS is the gold mine of circuits you should own and read You could start the first night building a project that will have others praising what it can do and admiring you for building it THERE ARE PROJECTS for everyone au tomotive household test equipment audio and hi fi and projects just for fun NEW IDEAS Circuits for Experimenters and Project Builders O Please send one copy of NEW IDEAS at 3 50 First Class postage and handling 1 00 U S and Canada only All other countries 2 00 for sea mail 3 00 for air mail copies of New Ideas Total cost is sum of copy price and First Class postage Allow 6 8 weeks for the material to arrive Detach and mail today HANDS ON ELECTRONICS Reprint Department 500 B Bi County Boulevard Farmingdale NY 11735 All Payment must be in U S Funds lm en em em em enen em m m em em em em em H1087 486i H38OLOO ere o ere HANDS ON ELECTRONICS e ACNAP APROGRAMTO ANALYZE AC NETWORKS Continued from page 46 is equal to the value of the VCCS in this case V times the value of the controlling voltage V into node V x Vc The controlling voltage can be equated to the voltage at the positive controlling node V and at the negative con trol
179. g single wire being used as the low impedance output coupling turn in the pas sive loop mode The flat cable coil is supported by a 30 mm wide strip of black fiber material formed into a circle The cable is fastened to it using black plastic tape That forms a self supporting circular loop which is still fairly light The loop may be easily plugged and unplugged into the housing and is clamped by a right angle bracket which in turn is secured by a thumbscrew on the back of the case The printed circuit board carrying the connectors for the loop the tuning capacitor output control and switches is fastened to the lid of the box which forms the front panel of the unit Fig 2 The circuit uses a FET buffer amplifier Q1 to provide amplification with high input impedance The output level control R2 can be used to adjust the output gain so as not to C4 strain your radios AGC on 470pF large signals 01 Cy VIEWED FRDM BELDW 470K 3 0 MPF102 The front panel is silk screened and carries a precision vernier dial for tuning a 0 10 indicator output level knob a 3 position band switch and a 3 position function switch A coaxial output socket is mounted on the PCB and protrudes through a hole machined in the side of the case How It Works Figure 2 shows the full circuit diagram As can be seen the coil is divided into four equal windings of two turns and one winding of one turn Note that there are two tu
180. gs In addition to this introductory offer you keep saving substantially with members prices of up to 50 off the publishers prices e Bonus Books Starting immediately you will be eligible for our Bonus Book Plan with savings of up to 80 off publishers prices Club News Bulletins 14 times per year you will receive the Book Club News describ ing all the current selections mains alternates extras plus bonus offers and special sales with hundreds of titles to choose from e Automatic Order If you want the Main Selection do nothing and it will be sent to you automatically If you prefer another selection or no books at all simply indicate your choice on the reply form provided As a member you agree to purchase at least 3 books within the next 12 months and may resign at any time thereafter e Ironclad No Risk Guarantee H not satisfied with your books return them within 10 days with out obligation e Exceptional Quality Ali books are quality publishers editions especially selected by our Editorial Board FREE when you join Reference Guide to Electronics Manufacturers Publications a time and money saving list of product literature from all the major electronics suppliers T Publishers Prices Shown Reference fei io Flectromecs value fanufacturers Publication Ae Erop Boan Cup le P O Box 10 Blue Ridge Summit PA 17214 Please accept my membership In the Electronics Book Club and send t
181. hang ing their values within a reasonable range should have little noticeable affect on the output voltages You should also try experimenting with different zener diodes D1 Voltage regulators are the most obvious power supply applications but there are other ways to use op amps in power supply circuits Voltage Current Conversion It is sometimes necessary to convert a Current into a volt age or vice versa a process that op amps handle quite well A simple current to voltage converter circuit is illus trated in Fig 5 If you know anything about op amps that circuit should look familiar The circuit is nothing more than Ri Fig 5 The current to voltage converter is simply an inverting amplifier minus the input resistor Output voltage is determined by the input current and feedback resistor LJ Vout a simple inverting amplifier minus an input resistor The output voltage is determined by the input current and the value of the feedback resistor and is given by Vat 1X RI Now let s say that R1 has a value of 330 ohms and the input current is 10 mA 0 01A In this case the output voltage would be equal to vs 0 01 x 330 3 3 Raising the input current to 25 mA 0 0254 increases the output voltage Vou 0 25 x 330 8 25 Obviously the output voltage changes in direct proportion to any changes in the input current With practical compo nents the op amp s input bias current will have an
182. hased trom Dig Key that prove to be defect d be replaced o retund a Add90 28 00 4 38 Less 20 4 as a hdi aA 3 ww ee uer ZER No Charge 10004 Up Less 26 aif t PRICES SUBJECT TO CHANGE WITHOUT NOTICE CIRCLE 8 ON FREE INFORMATION CARD 86t H38O01200 m HANDS ON ELECTRONICS NEW PRODUCT SHOWCASE 1000 towards future purchases and high quality software that includes a word pro cessing program a spreadsheet a data base a computer training program an assortment of RAM resident pop up pro grams and the Vendex HeadStart Oper ating Environment Enhancements to the hardware include a high speed intel 8088 2 micro processor that operates at either 4 77 MHz or 8 MHz clock and calendar cir cuitry with a battery backup system so that the clock and calendar are always operating two standard 360K floppy disk drives seven standard IBM compatible slots and a high resolution graphics card that is compatible with monochrome Hercules and color generated graphics at no additional charge At a starting price of 995 it also comes with with a high resolution TTL green screen monochrome monitor Bundled with the Turbo 880 XT are The Executive Filer from Paperback Soft ware MyCalc from Software Tool Works the ATI Interactive Trainer and a custom version of HOT the Desk Top Manager from Executive Systems At no time does the consumer have to read or study a manual ATI an interac tive tra
183. hat is for elements in De th row and the j th column A i j 0 is the real por tion of that element and A i j 1 is the imaginary portion Relating the A matrix to equation 1l the first N columns of A represent the left side of equation while the last column represents the right side of equation Needless to say solving for all the variables in an aug mented matrix larger than three rows can become a mathe matical nightmare But ACNAP can make analyzing even more harrowing circuits a snap so punch in those numbers and good luck Ld Am I going to have to put xou guys in separate rooms REFEREE Continued from page 80 your working area Edit your PATH state ment to include the subdirectory con taining Referee s files if you are using subdirectories So far it s simple You can then use Referee to manually control your programs Boot up your PC but don t load any resident programs Move to the subdirectory that contains Referee s files and type REFWATCH at the DOS prompt to load Referee s core program into memory Then load the rest of your RAM resident programs Type REFEREE at the DOS prompt You don t need to be in the subdirectory that contains Referee Just be certain that Referee Quick Start Card Installing Referee 1 Use the DOS COPY command to copy all of Referee s files into your working area Edit your PATH statement to include the subdirectory containing Reteree s tiles if you ar
184. hat treat ment effectively removed grime and cor rosion making the old controls operate quietly again With the chassis reassembled to the front panel cabinet assembly could now reconnect the wires to the four panel mounted switches Since those switches were permanently riveted to the panel had to disconnect them earlier making careful reference sketches of the wiring hookup in order to separate the chassis and cabinet Except for installation of tubes and control knobs the little Echo phone was now ready for testing In checking the tubes that had come with the Echophone against my Rider ser vice notes noticed that somewhere along the way a serviceman had re placed with glass types two tubes that had originally been metal Since happened to have the metal types on hand decided to switch back to the original configura By Marc Ellis New vinyl capacitor mounting grommets which are much more rigid than the rubberized originals were installed in place of the dried out rubber ones tion The complete tube set was then in stalled in the radio after having been checked and found to be good Now the set looks great and the next step will be to apply power and see what happens II report on the results in the next column The Echophone in WWII Recently two readers wrote in to share memories of their own experience with the Echophone ECI Both stories are as sociated with World War l a
185. he 5 volumes listed below plus my FREE copy of Reference Guide to Electronics Manufacturers Publications 2683P billing me 3 95 plus shipping and handling charges If not satisfied I may return the books within ten days without obligation and have my membership cancelled agree to purchase at least 3 books at regu lar Club prices plus shipping handling during the next 12 months and may re sign any time thereafter Address City State Zip Phone Valid for new members only Foreign applicants wilt receive special ordering instructions Canada must temit in U S currency This order subject to acceptance by the Electronics Book Club RESP 1087 Name MICROPROCESSOR VIDEO EQUIPMENT 2758 24 95 IC CIRCUIT a 6 95 2861 H380100 HANDS ON ELECTRONICS shouldn t the answer for the differential EE E te m Sedition Abstraction Uglification amp Derision On page 78 of the July 1987 issue amplifier in Fig 8 be 36 volts instead of 13 As the text states the sums of the inputs are calculated algabraically As far as know a 7 minus a 3 equals 4 Then E 9x4 36 If i m not approaching this properly please set me straight W J D Upland CA Part of the problem you re experienc ing isn t with math its with the sub scripts You are subtracting E from E instead of subtracting E from E So 3 minus 7 equals 4 Multiplying that by 9 does yield
186. he very least turn off the power switch preferably both when tak ing resistance measurements In addition when making in circuit resistance measurements it s necessary to discharge the filter capacitors by shorting them to ground If your ohmmeter is connected across a resistor in the circuit while Fg 028 210W 10 2082 10W EIGHT CHANNEL EFT HANNEL Fig 1 Always load the speaker terminals with 10 or 20 ohm 10 wett resistors while servicing high powered amplifiers When a hich DC voltage is found at the speaker terminal turn the volume all the wey down and do not connect resistor or speaker to the defective channel Joing so might cause further damage to the amplifier or destroy the speaker 861 H38O10O o J HANDS ON ELECTRONICS 8 The electronic technician is checking bias diodes and output transistors using the diode test setting of his DMM to make junction transistor measurements in an attempt to eliminate excessive distortion and hum in a Pioneer model SX 950 the capacitor is still loaded you may damage the meter once slapped my digital multimeter set to read resistance across a resistor that was near a charged filter capacitor And what I ended up with is an expensive continuity checker need say more Relay Problems You may find a small relay in the power supply that chan nels power to the amplifier circuits The relay is part of a delay circuit which provides protection fo
187. hould see what your fellow hobbyists have come up with DEPARTMENTS Editorial if you don t tell us how are we to know how best to serve you So keep the mail coming Letter Box lets your words be heard New Products Showcase tomorrow s products are here today Fuse Appliza ions pace 64 Bookshelf an information market for do it yourselfers and professionals FactCards we give you nothing but the facts Gadget the newsletter for grown up kids Free Information Card if you need more information about a future purchase the manufacturer is the one with the answers Antique Racios pace 30 amp 90 2861 H38O0100 Active Anzer na page 75 HANDS ON ELECTRONICS N The Magazine for the Electronics Activist In the mail bag We get the most unusual mail at our office The distribution of the various types of communications vary from the absolute junk mail to the reader who is responding to an item in a recent issue of the magazine The junk mail is claimed to be astronomical by the mailroom staff That does not make our job easier because we read it all Trade and professional magazines fall into this category find them very valuable Magazines intended for engineers scien tists and manufacturing specialists reveal what the trends in consumer buying activity will be from three months to several years from now For example back in 1977 forecasted a two billion dollar consumer computer mar
188. icant if only because a giant consumer introducing the Spectra also fabricated corporation has taken a gamble on the a giant sized walk through version of visual appeal of modern electronic cir the camera to generate public interest cuitry Design visionaries of a half cen But whatever the immediate motiva tury ago were enthusiastic about this tion the result is an extremely pleasing kind of industrial and in today s piece of consumer design It may not terms electronic beauty Now with be the beginning of a trend although high tech one of the trademark cli gadget fans can always hope but it s a ches of this decade Polaroid has intro wonderful item in itself When design An editing error scrambled a sen tence in our August review of the F R E D Ill Stereo Television De coder p 3 The line should have read F R E D II also offers SAP and MTS capability but lacks the built in amplifier of the ER ED IT Publisher Ai Goldstein Editor George Arthur Senior Editor Gil Reavill New Products Editor Christine Stevens Copy Editor Danny Jones Art Director Kevin Hein Assoclate Art Directors D Devins C Giordano Rob Weisberg Production Bill Mudie Administration Bonnie Keystone Reader Service Kathryn Hartman Technical Consultants Ken Schaffer Bob Bishop Con tributing Editors Philip Eisenberg Alan Freedman Jordan Ari Goldstein Steve Gruberg John Kois John Swenson Ken Swisher Aaron C Zimmerman G
189. ice The 2 1 5 or l ns risetimes are equivalent to 1 4ns Ins or 700ps for ECL work with 20 to 80 of pulse amplitude transition time definition Output impedance back matching ab sorbs more than 9546 of reflections from mismatched loads to provide very clean pulses under practically all conditions There is a choice of four output level ranges from 0 2 to 5 volts to match dif ferent circuit requirements Triggering duration and gating can all be controlled externally External trigger slope and level controls allow syn chronization with an external clock Ex ternal duration control enables the unit to function as a signal conditioner An exter nal gating control makes it possible to provide synchronized bursts of pulses Careful circuit design has made it pos sible to provide a burst option presettable from to 9999 pulses The number of pulses is set directly on the front panel and can be triggered manually or remotely via the external input Time setting error indicators confirm correct setting of repetition rate pulse duration and delay Pushbutton selection simplifies output pulse choice with no time consuming adjustment of inverter and or offset controls and a complemen tary switch allows instant inversion of the output without exchanging cables Prices for the PM785 start at 3 385 For more information contact Philips Test and Measuring Instruments Inc 85 McKee Drive Mahwah NJ 07430 3 Remote
190. ifferential amplifier The gain varies depending upon the op amp but few ever have a gain of less than 1000 Typically gains of 10 000 or more are common Direct coupled means that the internal transistor stages feed one another by direct intercon nections rather than passing signals through transformers or capacitors that block DC In other words a direct coupled amplifier will amplify DC as well as AC signals Also the op amp is usually of the differential configuration meaning that it has two inputs and a single output The output is the difference between the two inputs multiplied by the gain In many applications only one of the inputs is used Figure 2 shows the schematic symbol used to represent an op amp The inputs are labelled and Those refer respec tively to the inverting and non inverting inputs A signal applied to the input will be inverted shifted by 180 A signal applied to the or non inverting input will not have its pelarity or phase changed at the output Operation The thing that makes an op amp truly useable is feedback By connecting components such as capacitors and resistors between the output and one or both of the inputs both positive and negative feedback occur That greatly changes the characteristics of the circuit and most important makes its function mathematically predictable That is where the term operational comes from as it means some mathematical operation is performed by the op
191. ights In fact there are so many applications that you are limited only by your own imagination J A i By James E Tarchinski A program to analyze AC networks Now you can get a computer to do the number crunching for your circuit designs was first demonstrated at the University of Pennsylva nia in 1946 It is easy to imagine a witness of that historic event having thoughts similar to those of a mayor of the late 1800 s predicting the future of the telephone can see the time when every city will have one Back in 1946 it would have been hard to predict that in 1986 only forty short years later over fifteen percent of all Ameri can homes would have personal computers With the increase in the number of computers there has come a corresponding increase in the number of applications for those versatile devices Because they are nothing more than complex electronic circuits it should come as no sur prise that one of the major application areas for computers is the design and analysis of electronic circuits There are numerous computer programs on the market to analyze circuits and they all tend to have one factor in common they cost a lot of money Even small personal computer PC based analysts programs carry price tags any where from 1000 10 000 If you would like to have such a program for your home computer but you don t really want to mortgage your house to do it you have an inexpen sive option ACNAP
192. ime Touch Sensors raked front presents a gold finished map of the world with major cities indicated vertically divided into time zones Above the map two display windows indicate the zone and the correct day date and time for that location In order to bring up the desired time on the display it s only necessary to touch whichever time zone you re inter OCTOBER 1987 ested in Automatically the zone and the time displays go to the zone the user has pressed Setting the instrument is relatively simple Three buttons concealed under the battery compartment door on the back of the device control its multiple functions day date hours minutes and seconds Pressing all three buttons together activates the clock The user then touches the local time zone Button A activates the time calen dar setting mode Button B selects the set of digits to be adjusted signaled by flashing of the designated numerals minutes hours date month year and seconds in sequence There s also a choice between 12 and 24 hour modes of timekeeping Button C actually sets the indicated digits Once the date month and year are set the device auto matically displays the correct day of the week Once set according to Seiko the World Time Touch Sensor will auto matically adjust for odd and even months up to the year 2035 Seiko cau tions to make sure that the small AM PM display is correct in the 12 hour
193. ining program will take the user through all the computers s functions and capabilities In addition each software package is color coded and identified by Vendex s Headstart Operating Environ ment which makes using the Turbo 888 XT a breeze by leading the user through the computer s operations on a one key point and select basis All the user needs to do is move the cursor to a selection and press the help key which will then give them on screen information to proceed Every Headstart menu is presented in clear and simple English HeadStart also provides and gives the user control of custom utilities that in clude Custom Diagnostics all disc and file utilities available through MS DOS Oe Copy Format Check Disc and Erase DOS help screens and printer util ities that enable the user to set up the printer default for the specific printer being used In addition Head Start provides a utility program for the ad vanced user that will explain the powerful commands of MS DOS The Vendex Turbo 888 XT will ac commodate the most popular accessories because a parallel port a serial port a game port that can accommodate two joysticks a floppy controller capable of handling four floppy disk drives and an additional port to attach a mouse if desir ed are built in The unit will also accept an optional hard disk drive For further information contact Vendex Pacific Inc 40 Cutter Mill Rd Suite 438 Greatneck NY 11021
194. into three cate gories fast acting medium acting and slow blow The mate rial used for the fuse link and the construction technique determines what fusing characteristic the fuse will have A chart showing blowing time vs current is shown Fig 2 The proper choice here will also help eliminate nuisance blowing The medium acting or normal blow is the most popular and least expensive The fusible element is made from a medium to high melting temperature material and is made as small as possible to reduce the thermal inertia and speed up the blowing time There is very little time lag here so circuits that draw high currents when first turned on will cause that type to blow That type fuse is typically used in auto applications smaller appliances radios speakers etc They can be used very effectively to protect power supply voltages if placed after the rectifier filter capacitor assembly That serves to avoid passing the large surge current that the filter capacitor demands when the circuit is first turned on That is shown Fig 3 The transformer rectifier is also protected with a fuse in its primary The fast acting fuse is actually a specially constructed SEN 1A D Fig 3 A medium acting fuse is used as F2 to provide faster action while a slow blow fuse is used as F1 because of the surge current provided to C1 at turn on 2861 H380100 eo o NDS ON ELECTRONICS o HA eo If you look closely at this fuse you ca
195. itchen timer and an alarm which signals with either a reminder tone or by turning on the radio Price 99 95 2861 H380120 OCTOBER 1987 GADGET Page 11 o d HANDS ON ELECTRONICS Cn Co In years past ads in the backs of comic books often offered tiny cameras for secret picture taking While we never ordered one the prod ucts always intrigued us Now a German firm which has just entered the American market Personal Protection Products 405 Park Ave New York NY 10022 is offering a Wrist Watch Camera which is a real life ver sion of those comic book novelties of the past The fully operational digital watch conceals a miniature 35mm camera inside its case with the unobtrusive lens mounted above the LCD Eight exposures can be taken with one cassette of film The watch itself offers time calendar lap and alarm functions Personal Protection Products aims its line of security counter surveillance communication and investigative equipment at the security needs of the American business executive 7 The Wrist Watch Camera is one of many unique devices from the P3 catalog Price 2 450 Weight watchers dissatisfied with their present scale may be interested to know that Sharp Electronics Corp Sharp Plaza Mahwah NJ 07430 has entered the market for the first time The company has introduced three slim line home scales including the top of the line PH 430 Electronic Digital Scale The unit is a cordless
196. its 2 00 O 158 Electro Importing Co Catalog 1918 5 95 O 159 Low Frequency Receiving Techniques Building and using VLF Antennas 6 00 O 160 New Ideas 42 Circuits 3 50 O 161 Descrambling Feb 1984 2 00 C 162 Build Your Own Satellite TV Receiver 7 00 C 163 Receiving Satellite TV 7 00 O 164 Modern Electrics April 1908 3 00 O 165 How to Repair CD Disc Players 5 00 C 166 Collected Works of Mohammed Ullyses Fips 62 pages April Fools Collection 10 00 167 Designing With IC S 4 00 If you need a copy of an article that is in an issue we indicate is unavailable you can order it directly from us We charge 50 per page Indicate the issue month A year pages and article desired Include payment in full plus shipping and handling charge Make checks payable to Gernsback Publications Inc ARTICLE PAGES MONTH YEAR TOTAL PAGES a 50 each TOTAL PRICE MAIL TO Hands on Electronics Reprint Bookstore P O Box 4079 Farmingdale NY 11735 SHIPPING CHARGES IN USA amp CANADA 0 01 to 5 00 1 00 5 01 to 10 00 uaaa 1 75 10 01 to 20 00 2 75 20 01 to 30 00 3 75 Total price of merchandise 004 Sales Tax New York State Residents only Shipping see chat Name Address City State Zip 30 01 to 40 00 4 75 40 01 to 50 00 5 75 50 01 and a
197. ivity from the receiver Note that the loop tuning is not so sharp as to require constant tracking with the receiver It is possible to move the receiver tuning a reasonable distance away from the loop resonance without losing reception As previously mentioned to obtain optimum tuning and direction particularly for weak signals it helps greatly to reduce the output level of the loop to the point where the AGC action of the receiver begins to drop out indicated by a sudden increase in background noise and a decrease in signal level After finding the optimum tuning for the loop the output level may then be restored to maximum Continued on page 105 2861 HASOLOO J oO HANDS ON ELECTRONICS CO e Persoft RAM Resident Management Program persojr New utility designed to manage RAM Resident software You REALLY LOADED UP YOUR RAM chips You packed into resident memory goodies such as keyboard enhancer word processor spelling checker thesaurus spread sheet desktop organizer and more What convenience But then vou pressed F3 that activated two or more resi dent programs causing computer lockup Too much of a good thing did vou in Don t despair for there is hope tor vou in the form of Referee a software manager of RAM resident programs Referee was designed to allow microcomputer users to load multiple memory resident programs without fearing the data loss maltunc tuons and keyboard
198. k until the circuit oscillates Then fine tune it for its best waveform Set the potentiometer for maximum peak to peak amplitude just before clipping begins Observe the output It should be a clean sinewave Measure the frequency by deter mining the period t of one cycle on the calibrated scope graticule Compute the frequency f using the expression f I t Record your value below f Hz 22 Compute the frequency using the values in Fig 17 and previously given formula f Hz It should be close to the value you measured Looking Back On Steps 20 22 The Wein bridge oscillator is simply a non inverting op amp with positive feedback The resistor network between pin and pin 2 sets the gain of the circuit The light bulb is used as an automatic gain control denoted AGC element During oscillation the output amplitude will increase until the saturation limits of the op amp are reached Therefore the output will be a square wave switching between 8 5 and 8 5 volts instead of the desired sinewave The lamp has a positive temperature coefficient meaning that its resistance increases with the current through it f the output voltage rises the current in the bulb rises increasing its resistance That decreases circuit gain reducing the output below the point of distortion The result is a stable output level The circuit with the diodes in the feedback circuit of Fig 17B does essentially the same thing If the output ris
199. k drives First you can use more than one hard disk the WX and WX 2 controllers have connectors for two hard disk drives Second the drives need not have the same capacity If you start out with a 10 megabyte drive to keep costs at rock bottom you can add a 20 megabyte drive in the future it s the assortment of programming pins on the Western Digital controllers that allows you to mix n match E NEW PRODUCTS Continued from page 13 information contact Panasonic One Pan asonic Way Secaucus NJ 07094 Proton Loudspeaker System Housed in the distinctively shaped AL 300 cabinet is a one inch polyester soft dome fluid cooled tweeter chosen for it s response capability and high power handling ability The midrange driver is a 3 5 in treat ed cone mounted in an integral air suspen sion sub enclosure It incorporates an Il ounce magnet creating a 12 kilogauss flux density The 12 in air suspension woofer op erating with a 30 ounce magnet greatly reduces harmonic and intermodulation distortion even at high power levels The crossover design operates each driver over a relatively small frequency range to reduce system distortion and in crease power handling capability Ex treme off axis radiation is intentionally limited to reduce unwanted room reflec tions and stabilize the stereo image The distinctive angle of the AL 300 front panel aims the axis of radiation di rectly at the useful listeni
200. ketplace That s pre IBM PC Yes was laughed at Today that sum is a drop in the bucket Other mail informs me of new scientific developments new products buying trends trade meetings and Shows throughout the world and of course financial reports from successful com panies The latter sold my father on a dinky little company that sold a Polaroid camera back in the late forties This mail is valuable because it tells us provided we are perceptive enough what will happen to our hobby industry in the future And of course we receive lots of reader mail We have all sorts of readers out there from whom we get a corresponding diversification of ideas complaints suggestions almost all the articles you see in this issue you name it we read it And it s in the reading of your mail that we form in our minds the composite voice of you We get to know you better than some Madison Avenue huckster s readership survey would presume We have only one fault with the mail it s the volume We cannot hope to answer every letter sent to us Some we do most require no answer Many letters are grouped and presented in our Letter Box column with comments from our staff we answer many letters that way Nevertheless we want you to write Your response letters to our actions magazine makes for a better Hands on Elec tronics Please give us a hand Vm the Julian S Martin KA2GUN Editor Volume 4 No
201. l V The reference is simply a DC voltage or other level that is used as a standard against which the input signal is compared When the input signal value is less than the reference value the comparator output will be one of the two saturated states depending upon the polarity of the input As the input signal rises at some point it will become equal to the reference voltage At that point the output voltage will switch to the other saturation level In creasing the input level beyond the reference level continues to hold the output in that saturated condition Note that the comparator is used open loop that is without feedback That allows the maximum gain of the op amp to come into play so that precision comparison can take place In order to cause the amplifier to switch from one state to the other a small amount of input voltage difference is required For that reason the comparator does not switch exactly when the two input signals are equal But the higher the gain of the amplifier the smaller the difference in voltage required for output switching and the greater the precision Figure 10 shows a variation of an op amp comparator Here the non inverting input is grounded and the two signals to be compared are applied to two equal summing resistors In order for the circuit to work properly the polarity of the reference must be opposite to that of the input signal Note also that a zener diode is connected as a feedback eleme
202. l find in this compact easy to read book setting up the comput er working with the keyboard setting up the cassette recorder saving and loading programs on cassettes setting up the disk drive a bibliography to help find more information booting and exploring DOS CIRCLE 52 ON FREE INFORMATION CARD saving and loading programs on disk driv es playing around with sound using the printer for letters programs and graph ics using the modem to connect to the outside world using the modem to con nect to the outside world and a glossary Also special chapters on software word processing financial management data base management education games and graphics The working programs contained in the text include drawing programs to create pictures on the screen and save to cassette or disk a tutor program to create question and answer quizzes on any topic you wish and a budget program to create ex pense reports and reconcile your check book The 120 page softbound edition costs 5 95 from Info Books PO Box 1018 Santa Monica CA 90406 Computer Integrated Manufacturing Handbook By Eric Teicholz and Joel N Orr If you re into letting machines do all the work then this is for you A highly practical treatment of the in creasingly important technology of CIM the book presents vital information for understanding and implementing issues in easy to understand terms McGraw Hill 59 95 Und
203. l hold color tint picture detail black level or contrast plus bass treble and balance Other switches there adjust the 625 for cable use mono or stereo audio computer dis play automatic or manual fine tuning and second audio program recep tion There s also a two position Switch to engage the Proton s video noise re duction system Add erase and tadd erase skip controls allow a user to set the 625 s channel selection for only those channels actually trans mitting Finally behind the same door is the monitor receiver s third set of stereo audio video and TV out jacks TV out allows any TV chan nel to be recorded even when the 625 is taking its programming from an other source such as a VCR The back of the set presents further controls and a multiplicity of inputs and outputs suggesting the Proton 625 s studio origins Besides the master power switch there are con trols to disable internal speakers for using the 625 with external audio equipment and a sync positive nega tive adjustment for use with RGB components There s also something called a 356 trap which is not ex plained in the manual until the trouble shooting section Apparently this trap locks out interference emanating from the 356 MHz band which can make the unit s picture fuzzy Proton says this monitor receiver achieves horizontal resolution ap proaching 400 lines
204. layer loop is suitable for the top end of the broad cast band right through the 80 meter and 40 meter amateur bands and into the international shortwave bands Note that the figures given are for 300 mm loop For larger diameter loops the frequency range for the same turns would be shifted down proportionately Larger loops will give more signal capture but in practice the 300 mm size is convenient and quite adequate for most applications par ticularly with the FET buffer stage The top trequency with a single layer 300 mm loop is 13 5MHz To go higher with the existing circuit would mean reducing the diameter of the loop which would negate the advantages if taken too far Note also that the advantages of a loop tend to diminish with increasing frequency with directionality becoming vague and the signal talling off The three loops cover the range of frequencies from 200kHz to around 13 5MHz There is a new design that even covers up to 24 MHz by using eight strands with a 380 mm diameter PARTS LIST FOR THE ACTIVE ANTENNA CAPACITORS Ci 10pF 16WVDC tantalum C2 0 1uF ceramic disc C3 01pF ceramic disc C4 0 470pF variable ADDITIONAL PARTS AND MATERIALS D1 1N914 small signal diode Ji Coaxial jack PL1 PL2 IDC 16 conductor connector C1 MPF102 N channel FET Ri 470 000 ohm watt resistor R2 1000 ohm miniature potentiometer SCH SO2 IDC 16 conductor socket 81 86 pole triple throw
205. laying around with sound CIRCLE 52 ON FREE INFORMATION CARD using the printer for letters programs and graphics using the modem to connect to the outside world and a glossary definitions and fun with computer terms and special chapter on software word processing financial management data base management education games graphics There are three working programs a drawing program to create pictures on the screen and save them to cassette or disk a tutor program to create question and an swer quizzes on any topic you with and a budget program to create expense reports and reconcile your checkbook The softbound book contains 128 pages and costs 5 95 from Info Books PO Box t018 Santa Monica CA 90406 Tel 213 470 6786 How to Design and Make Your Own PCB S By R A Penfold A lot of electronics enthusiasts either don t know how to make their own PCB s or haven t gotten their technique straight yet Perhaps this book would be useful to those of you in either category The pur pose of the book is to familiarize the read er with both simple and more sophisti cated methods of producing printed circuit boards The subject is not covered in a vague and purely theoretical manner as the em phasis of the book is very much on the practical aspects of printed circuit board design and construction Chapter deals with simple methods of copying PCB designs from magazines and books and covers all aspect
206. lding the test lead in contact with MIZ release the test lead from the gate If the resistance does not stay low in any one of the test situations you probably don t have sufficient current flowing through the device to keep it turned on This may be true for high current devices In that case try to use another VOM that provides a higher current for resistance measurements Also it helps to have a fresh battery installed in the VOM Change the polarity of the test leads and repeat the whole procedure in order to assure yourself that you are dealing with the Triac and not with an SCR which behaves just like the Triac except that only when its cathode and anode are connected to negative and positive terminals respectively with its gate being triggered with positive voltage only refer enced to the cathode Construction and Applications Putting the Temperature Controlled Soldering Station to gether is quite simple and rather straightforward The au thor s prototype unit was built inside of a discarded light dimmer housing However the circuit might just as easily be built on perfboard or if so desired on printed circuit board the choice is up to you If perfboard is used mount all components to the board Then using insulated wire connect the components as shown in Fig I Figure 4 is a block diagram illustrating the finished basic circuit with the box representing the circuit board PLI N G L S01 Fig 4
207. le the shortwave bands of all wave radios that came into their shops For security reasons the ci vilian population wasn t supposed to have access to those bands can t imagine any other reason for the wire having been re moved but its hard to understand how such a policy could have been effective There must have been many radios that like Dan Scheer s Echophone made it through the war without a service call Would it have been technically illegal to listen to shortwave on those radios Since the war has been over for some time felt I could replace the wire and b e still be considered a loyal citizen However it would be very interesting to learn more about wartime government policy on shortwave listening Are there any readers with information to share Please write me C O Hands on Elec tronics S00 B Bi County Blvd Farm ingdale NY 11735 The Dayton Hamvention Last month April E attended my first Dayton Hamvention said to be the big gest annual ham radio get together in the world had a super time from a ham radio point of view and picked up many items needed for my station But as an antique radio collector I was a bit disappointed Only a few sellers at the 1800 table flea market had much in the way of antique gear and prices seemed to be rather high The spirit and camaraderie among the par ticipants at the event are great however And if you d like to immerse yourself in h
208. lectronics is also a great gift for you to give The Special Holiday Rate saves you 9 00 off the regular subscription price on each gift You can save another 9 00 when you start or extend your own subscription at the same time It s our thank you for sharing the Hands On experience with a friend this Christmas Send no money unless you prefer We ll be glad to bill you in January Next Year Just take a brief moment to go over your gift list and make sure you haven t forgotten anyone who might appreciate the Hands On exper ience Then write the names on the attached Gift Certificate and mail it back in the postage paid reply envelope we ll take it from there Your friends will receive a handsome gift announcement card signed with your name just before Christmas And all through the new year they ll remember and appreciate your thoughtful gift of Hands On experience So don t blow a fuse take it easy and enjoy the holidays Give Christmas gifts of Hands On Electronics 2861 H380100 o Zoch HANDS ON ELECTRONICS o gt By Jack Cunkelman FUSE IS BY DESIGN THE WEAKEST LINK IN ANY A circuit that uses them When that link lets go and interrupts the supply voltage before the circuit is damaged by an over current condition we are given a second chance The fault condition is cleared the fuse is replaced and life goes on Circuit designers include fuses in their designs to give
209. ling node V by writing VV EN Therefore the expression for the current into node is given by the equation into node V x V V4 Or l into node V x V V x V Eq 3 The effects of the VCCS on node 2 are the same as above except for a sign change That is into node 2 V x Vi V x V Eq 4 The terms represented by equations 3 and 4 would gener ally appear on the right side of equation 1 However be cause they contain references to other node voltages in the circuit ACNAP changes their signs and puts them on the left side of equation That accounts for the different signs found in lines 2690 and 2700 of ACNAP The A Matrix As mentioned earlier nodal analysis requires that one equation be written for each node of the circuit to be ana lyzed Now that we know where those equations come from let s take a brief look at how ACNAP actually handles the KCL equations ACNAP enters those equations into an augmented N row by N I column matrix Each row in that matrix represents the KCL equation for the corresponding node of the circuit That is row is the KCL equation for node row 2 is the KCL equation for node 2 and so on The first N columns of the augmented matrix represent the terms in the KCL equations that are dependent on the corresponding node voltages The last column represents the constant terms of the KCL equations The constant terms arise from the current supplied by indepen
210. ll probably have to remove the B drive so that you ll have mounting space and power for the hard disk drive whether it s a half or full size drive If you have one of the newer computers it probably has half size drives and a power supply of at least 120 watts that has two sets of extra power connectors a total of four You can fit either a half or a full size hard disk drive into the empty panel space and then simply plug it in to the power supply Now it s conceivable that your el cheapo hard disk unit will arrive without a front panel Surprise That wasn t even implied in the advertisement No problem Simply make your own from one of the plastic filler panels that cover the disk drive openings in the front of the cabinet just press the filler forward and out or cut a piece of plastic to fit The panel doesn t have to attach to the drive because the drive is really held in place by two to four screws not by the front panel The panel contains only two LED s which indicate that power is on red and that the disk is in use green or yellow The connector tor the LED s are three pins near the front of the drive Simply install two LED s on a plastic filler panel see photos Tie one lead from each into a common connection which is usually negative and pre wire the three leads to a connector that matches the three pins on the disk drive If your hard disk drive came without a front panel you can make your own by
211. lockups that some limes accompany the use of those programs Referee lets you keep incom urrantly Loadad RAM Raeidant Programa Reeident programe loaded 3 Reeident programa active 3 PA NN s Pro amp ey 4 SideXick 4 indicetee currently ective programe Keybosrd Ueeg Activate desctivete Activate all Deectivete oii nd Move cureor Cursor to leet Unloed eelactad program and ell thet were loaded efter t Fig 1 Referee lets you look at currently Ioaded RAM resi dent programs The screen image shows all the resident programs in the order in which they were loaded Notice that descriptive names as well as file nomenclature appear Referee lets you designate a descriptive name for each program in place of its filename it s up to you Memory usad by reeidant programa 103K Totel free memory 463K G Cursor to firat patible RAM resident programs away Irom each other while it allows users to customize their computing environments It alleviates many of the technical support headaches that RAM resident incom patibility has caused Keteree allows users to set up Ram Teams in which only pre specified RAM resident programs are activated with a particular application program When a user switches to another applica tion program Referee will automatically and invisibly disable unnecessary RAM resident programs and enable the ones that are necessary For example In a net work situation the P
212. lter filter so any high pass will show our high class Thanks for pointing that out and hope this reply didn t cause too many groans Head Case built a Fred the Head and al though not completed his mouth eyes and microphone pick up work fine His eyes really do light up modified his mouth circuitry and I m constructing an FM wireless transmitter so I ll be able to hear anyone who wishes to talk to me from a short distance Can you imagine the effect carrying on a conversation with that wooden head R E C Atoka OK Its a great way to keep the kids busy If anyone else out their has come up with an interesting twist for any of our proj ects please let us know Auge m EE ly that can undercut a published price They do it by having no overhead and no responsibility to you the consumer So you want that Jerrold 450 combo The one that Pacific Cable Ce lac is offering for 19999 Well that s a good price but here s what ll do What may happen is that you may save a couple of bucks at the time But suppose there s a problem and it happens to the best of them and you call that Dealer This could be what you ll hear No Steve isn t here He moved out the bum And he owes me 437 on the phone bill No don t know about any guarantees on your Gerald who s that Listen if you see that creep etc At Pacific Cable Ca you ve got an est
213. ly new technology Quiet er freer from distortion easier to construct ideal for home builders Audio amps all wattages 15 AM PLIFIERS UNLIMITED Rt 2 Box 139 Highmore SD 57345 FREE microprocessors memory chips etc Free electronic magazine subscriptions Free education in computers For information write MICRO SAT LLITE CORPORATION 2401 N E Cornell Bldg 133 mail stop 140 Hillsboro OR 97124 EXPERIMENTER plans kits for your Commodore Apple TRS 80 computer Wireless controllers D C Motor controllers speech processor multiple W O robot controllers software available Catalog 2 00 ROBOX P O Box 193 Verona WI 53593 BUILD economy Eprom programmer Plans plus two additional projects 2 50 plus 1 00 S H Bonus included GALLIUM JUNCTION 540 C N E North gate Way Suite 542 Sea WA 98125 TUBES over 2000 types including early and hard to find Parts and literature for antique radio restorations Send 2 00 for 20 page catalog to ANTIQUE ELECTRONIC SUPPLY 688 C West First Street Tempe AZ 85281 CABLE EQUIPMENT CABLEL TV Secrets the outlaw publication the cable companies tried to ban HBO Movie Channel Showtime descramblers converters etc Sup pliers list included 8 95 CABLE FACTS Box 711 H Pastaskala OH 43062 FOR SALE LASERS Surplus parts and units the source for lager surplus Free catalog MEREDITH INSTRU MENTS DO Box 1724 ale AZ 85311 RESISTORS 1000 assort
214. m memory even programs that provide no unload option of their own The latter is an important feature You can use a TTL composite or color monitor to view the menus of Referee and you can eliminate the color which will ently Lesded RAM Res dent Progr Resident programe losded 4 Resident programs active A 4 PRITMONO COK Prekay 4 BideKick 4 Bide PYLOAD COM Prekey Filename J indicatee currently active pregrane Memory used by resident programs 113K Total free menory tailed Iaformation Status Descriptive mame Active Gideline Referee Vere on 1 0 E deck to prav nesu Fig 3 Sideline Referee informs you of which RAM resident programs are currently active and inactive how much RAM space they use and allows the user to activate or deactivate them 5 Use the first menu Activate Deactivate RAM resident programs to manually activate deactivate and unload your resident programs A check mark denotes active Using Referee to automatically Control your programs 1 Follow the directions given above to load and access Referee 2 Use the second menu Tell Referee about your RAM resident programs to enter the names of any RAM resident programs you plan to use 3 Use the third menu Specify applications and their RAM Teams to enter the names of any application programs you plan to use and to designate which RAM resident programs you want active inactive or unchanged with ea
215. m E Ec g ess m Nd i ER Q9 Ke s e R we n 01 OIRECT PATH SPACE WAVE CVR eK a Nd e arat Fig 3 There are four major propagation paths surface wave space wave tropospher ic and ionospheric The surface wave a ground wave travels in direct contact with the Earth s surface and suffers a frequency dependent attenuation due to ground absorp tion which increases with frequency The space wave also a ground wave phenomena is radiated from an antenna many wavelengths above the surface and no part of the wave normally traveling in contact with the surface The troposphere is the region of our atmosphere between the surface and the stratosphere in which all forms of ground waves propagate The ionosphere is the region of Earth s atmosphere above the around the object The umbra region or diffraction zone between the shadow zone cone of silence and the direct propagation zone is a region of weak but not zero signal strength In practical sit uations the cone of silence is never really zero A certain amount of reflected sig nals scattered from other sources will fill in the shadow a little bit stratosphere wherein molecules of air O2 and N can be ionized by stripping away electrons under the influence of solar radiation and other sources of energy ee 861 HAEOLDO e RS HANDS ON ELECTRONICS wW eo Trier OF YOU WHO HAVE BEEN POL lowing the last few columns already know about
216. me value should have been close to that Further Steps You will now use the integrator and comparator to build a signal or function generator 17 Be sure power is removed Then disassemble the circuit and build the new circuit shown in Fig 15 That circuit combines the integrator and comparator circuits to form a function generator that produces square and triangle wave lorms 18 Apply power to the circuit Monitor the outputs at pins and 7 with your volt meter Name the output waveforms at each pin pin 1 pin 7 19 If you have an oscilloscope you can monitor the square and triangle waves To do that change the feedback capacitor to l wR Change the 10 megohm integrator input resistor R1 to 10 000 o0hm Then look at the waveforms at pins and 7 You should see near perfect square and triangle waves occurring at a frequency of approximately 550 Hz Review of Steps 17 19 The circuit in Fig 15 uses an integrator and comparator connected in a feedback loop The comparator input pin 6 is connected to ground so that the reference is zero volts Note that the input is used for the reference instead of the input as in the earlier circuit The integrator output is applied to the other comparator input through the 10 000 o0hm comparator input through the 10 000 ohm resistor R2 Along with the 22 000 ohm resistor R3 it forms a voltage divider that sets the output amplitude of the triangle wave The integrator charges or discha
217. ment by various combinations of depressing its two adjusting pins the entire process soon began to resemble being lost in a maze But this is a longstanding gripe which 3 jacks the video snapshots from the printer taken from the 625 s screen were exceptionally detailed while the color was balanced and even natural in appearance After living with the Proton 625 for a month at GADGET s office a high tech hearsay suggested itself What put the notion in our minds was a further note in the owner s manual In discuss ing antenna and cable connections Proton added as a note that it does not recommend the use of indoor rab bit ear antennas We re sure there are technical grounds for this but we re also pretty certain that if Proton had anything to say about it the com pany would not approve using this monitor receiver to watch reruns of The Beverly Hillbillies or Mr Ed either If you want to watch that kind The Levitator we have with most digital display wrist watches For all the advances in minia turization and multi functionality ad justment and setting are still too often crude and unwieldy If multi thousand dollar computers can be user friendly why should we expect to get the cold shoulder from a 25 watch Despite cautions about shortening the life of the Voltaic cell the Water Watch will operate with liquids other than water such as beer wine cola and so oni The damage results because th
218. n e E Wort Restor anortmants SEBES Z EEK an B8 yD amie a d XN 10 31 744 515 1N 744 5 153 KE nd ML 231 Sab JA S 18 741 18 PN 744 3 Sn S160 IUBE E35 SESSSERSHREE 3 each ot e 18S icis pcs wo CAPACItORS SE ggg E S i M d Va h e bin H 4 i 70 Watt Hasiio Raacoctrant ASSORTMENT OF 1 M e Le POPULAR mi oe any st Art 1 s Ce Ken emie CAPACHORS The DigiKey volume discount nd service charges are simple 10 apply Most itema sold by Dep Key may be combined for volume discount terns that are not decounteble we identhed by the suffix pe NO following ihe pan number After writing your order total AN of the discountabie tems and apply the appropriate discount To this subtotal add the non discountabie items Then add the service SERVICE CHARGES VOLUME DISCOUNT charge We pay l shipping and insurance to addresses in the U S A Canada snd Mexico when check o money order accompanies of de Digi Key onty sups orders withen the continental U S Alaska 9 0 00 9 9 99 Add 2 00 0 00 s 98 99 NET Hawes Canada and Mesco 10 00 925 00 Add 0 75 100 00 9249 99 Less 10 WHEN ORDERING BY PHONE CALL 1 800 344 4539 AK col 218 620 6674 BY Mail SEND YOUR ORDEA TO DIGIKEY P O Box 677 Thiel Rive Falls MM 56701 d T Acid 0 50 250 00 6489 99 Less 15 You may D r by ch money order Masier Charge VISA C O D O GI MEY GUARANTEE Any pans of products purc
219. n tial amplifier 3 Demonstrate the operation of an integrator 4 Demonstrate the operation of op amp oscillators and function generators 5 Demonstrate the operation of an op amp comparator Comparator Cutput Indicator Since the polarity of the cp amp output switches from to it is inconvenient to keep reversing the volt meter leads to keep the polarity correct One way to overcome that problem is to use an indicator light to tell the output state The circuit shown in Fig A uses a Switching transistor to turn an LED off or on depending upon the comparator output state When the op amp LEO COMPARATOR 2200 2N2222 output is 4 8 5 volts the transistor turns on lighting the LED When the comparator output is 8 5 volts the transistor is cut off therefcre the LED does not light The transistor can be any common NPN unit A silicon diode of any kind protects the transistor 86 HABOLOO Qo i HANDS ON ELECTRONICS Background Tutorial The IC op amp is one of the most useful electronic compo nents ever designed Op amps have done for linear analog circuits what logic gate IC s have done for digital circuits Op amps are like logic gates a basic building block Vir tually any kind of linear circuit can be constructed using op amps Because of their flexibility you can build an amazing variety of precision analog signal generating and processing Circuits An op amp is a high gain direct coupled d
220. n is one You set the V input to 2 volts The V input comes from a voltage divider that supplies approximately 3 volts Now using the formula you should have computed an output of Vo 100 000 100 000 2 100 000 100 000 3 Vo LA 3 5 5 volts Your measured value should be the same Note that the circuit does perform addition but tts inver sion changes the polarity but not the absolute value of the output OP AMP IN FUNCTION GENERATOR TRIANGULAR WAVE c 100K 100K o MIXER OUTPUT Of AMP IN OSCILLATOR SINE WAVE Fig 19 This circuit not only adds the triangle and sine waveforms together it amplifies one of them as well Signal Mixing n the following steps you will demonstrate a linear mixer 27 Turn off the power and rewire the summer circuit so that it appears as shown in Fig 19 The only change is the replacement of one 100 000 ohm resistor with a 22 000 ohm unit One input will come from the triangle output of your function generator circuit The other input will come from your Wein bridge oscillator Continued on page 101 2861 4380190 ON ELECTRONICS HANDS GARR ON HAM RADIO By Joseph J Carr K4IPV JONE MORNING GOT UP PARTICULARLY early and being too lazy to fire up the rig to see what VK ZL goodies were on 40 meters CW flicked on the little B amp W TV in our bedroom A strange test pattern bloome
221. n by learning BASIC But as computer lan guages go BASIC is slow and cumber some Now with Borland s affordable Turbo Pascal software individuals and small business owners are seizing the op portunity to step up to a high level struc tured language for faster more efficient programming In this book Paul Garrison draws from your knowledge of BASIC programming fundamentals to show you how Turbo Pas cal works BASIC programs are com pared side by side with their Pascal equivalents so that you can see clearly the TURBO PASCAL FOR BASIC PROGRAMMERS i e a CIRCLE 58 ON FREE INFORMATION CARD Look inside this book and find clear and easy to understand explanations of the specifics of structured programming with Turbo Pascal a library of useful pro grams for personal and business uses There are for example database pro grams a financial projection program a currency conversion program a mortgage amortization program and many more seven appendixes that include the ASCII character codes a Turbo Pascal diction ary a glossary of computer terms and ab breviations and other helpful aids If you want more information about Turbo Pascal procedures and functions loops and arrays pointers heaps and stacks Turbo Pascal for BASIC Program mers is for you A hands on tutorial this book shows you how to use Turbo Pascal to turn your computer system into a powerful develop
222. n see the spring that keeps the filament in tension Close inspection of a fuse can often times reveal the source of trouble e END UN ei Pd AS LOW MASS SUPPORT BEAD FUSE WIRE Fig 4 This is one method of construction used to build a fuse with very fast blowing characteristics in a 3AG case medium acting fuse The fuse element is made physically very small so the thermal inertia is very small Figure 4 shows one method of constructing a fast acting fuse in standard 3AG series fuse case Subminiature microfuses and picofuses are usually considered fast acting type fuses because they are physically so small which makes the element small The fast acting fuse is used to protect sensitive instruments where even a small amount of overcurrent would damage the device You are not likely to run across many of those The slow blow or time delay fuse introduces a special dual construction technique to provide two way protection Figure 5 illustrates that two way protection The normal medium acting link will blow if a short circuit condition exists The slow blow fuse however will stand many current surges and current overloads for a long period of time because of the additional solder junction The solder joint has a high thermal mass and takes a long time to melt and break loose A spring attached to the element at the junction assures a clean break when the junction melts The slow blow fuse is used in circuits that can tolerate cu
223. nch white pine lumber If the scrap lumber is already painted place it on the inside of the cabinet Run a line of wood glue between the board ends and place two small finishing nails to hold the pieces together Nail and glue the bottom panel to the cabinet The top panel is held to the cabinet with eight metal screws Round off the corners of the cabinet and panels with a bench sander if handy Countersink the finishing nails so that the corners can be rounded off Finish up with fine sandpaper on the side and corner areas Spray two coats of metallic silver automotive paint on the wooden cabinet Two coats of black auto spray paint is applied to the front panel before it is mounted Sand between coats with real fine sandpaper or steel wool ANT TUBE SLOT pe TUNING OIAL C3 TUNING CAPACITOR Connecting Together Bolt the ground and antenna post in their respective holes on the front panel Refer to the photos Next mount the miniature variable tuning capacitor Fasten the perfboard to the top panel with the control nuts The antenna ferrite coil is not glued into position until Grandpa s Antique Radio is operating Connect the two wires to capacitor C3 with the ground wire going to the rotor terminal of the capacitor Solder the EE a ia E 6i m CABINET SIOES L TWO CABINET ENOS MADE FROM 1 IN MADE FROM 1 IN WHITE PINE WHITE PINE CORNERS ROUNOEO OFF WITH BOTTOM PANEL IN PLACE ANO TOP PANEL TEMPORARILY FASTEN
224. nd IO times the normal load current fuses rated at 125 and 250 volts may be used at much higher voltage levels To state it another way If the short circuit current will not be excessive a fuse can be used in a circuit with voltages higher than the fuse rating Current Rating The other number on the fuse cap is the current rating That rating everybody understands That is the amount of current that the fuse link can carry almost indefinitely When the circuit draws more current than the fuse link is rated for the link melts the fuse blows and interrupts the supply voltage to the circuit It s almost that simple but a few other considera tions must enter the mix It is considered good practice to only load a fuse to 75 of its current rating That then takes into account the manutac turing tolerances and eliminates nuisance blowing Some manufactures derate by as much as 50 Car radios tor instance usually draw about 3 or 4 amperes but are fused at 8 or 10 amps Under a short circuit fault condition the fuse will blow but it will not blow when your favorite song comes on and you crank it up The ambient temperature also has an effect on the rating That is shown in Fig 1 As expected since the fuse link is a thermal mechanism as the ambient temperature goes up the fuse must be downrated i e a higher amperage fuse used Wide fluctuations in the ambient operating temperature of a piece of gear can cause fuse fatigue and mysteri
225. nd both readers still have the ECI s in their posses sion While stationed in England with the Eighth Air Force George Pearson of Massapequa NY kept in touch with war news on a variety of home made re generative receivers When the war in Eu rope ended he was sent back to the states lor redeployment to the Pacific George decided to take advantage of a short furlough in New York City to find a better radio for the Far East Campaign Radios were scarce on the civilian mar ket but through a friend George was able to locate an Echophone ECI De lighted he packed it carefully into his duffle bag leaving behind some clothing to make room The bag and radio were soon lost having gone astray on a crowd ed troop train George had given up hope of ever seeing his new purchase again But amazingly enough the bag turned up at a lost and found office days later n ON e After a thorough cleaning the tuning capacitor was placed back in place on the chassis Note that one of the two dial cord systems has been restrung za George never made it to the Pacific The atomic bomb brought the hostilities to a close while he was still on temporary assignment at Charlston Air Force Base Thanks to the EC George was one of the first people on the base to hear about the bomb Using a bedspring antenna he picked up the news one morning on an Australian station Our other World War H story comes from Dan Scheer who served
226. nd for best results should be matched to minimize differences due to tolerances You don t need to resort to 1 resistors The exact value is not as important as close matching between the two resistors Because R4 and R6 are equal the voltage at their junction should be zero if the regulated V output is equal except for the inverted polarity to the regulated V output The signal at the R4 R6 junction is fed to the inverting input of U2 through resistor R5 If the two regulated outputs are not equal for any reason perhaps due to unequal loading a non zero signal will appear at the inverting input causing the U2 s output voltage to shift increasing or decreasing the base current to Q2 Since V is regulated by the other half of the circuit changes in Q2 s base current cause it to adjust the V output in the desired direction One major advantage of the circuit is that even if the output voltages change momentarily they 1l maintain their symmetrical relationship because the regu lated V output is referenced to the V output Proper sym metry is more important than exact voltage in many circuits especially those using bipolar op amps The exact component values may vary for specific appli cations Experiment to gain familiarity with the circuit You can try varying the input voltages and the output loads or experiment with different transistors and resistor values The exact values of R5 and R7 aren t too important and c
227. ng area in a real world monitoring situation The panel also helps to integrate the radiation from the individual drivers and limit the amount of midrange and tweeter energy reflection of the floor The cabinet is braced to suppress ener gy storage and superfluous radiation Acoustically absorbent felt eradicates cabinet diffraction and reflection effects and improves stereo imaging System sensitivity runs just over 90 dB at one meter for 2 83 Ne of pink noise 500 Hz to 5 KHz bandlimited The input impedance averages 6 ohms minimum 3 3 ohms to allow maximum power transfer from contemporary amplifiers The Proton AL 300 loudspeaker sys tem has a suggested retail price of 899 00 pair The proton D540 ampli fier has a suggested retail price of 299 00 The D1200 amplifier has a sug gested retail price of 599 00 For more information contact Proton Corporation 737 West Artesia Boule vard Compton CA 90220 I said up OP AMP APPLICATIONS MADE EASY Continued from page 87 28 Change the values of the 10 000 ohm resistors R1 in the Wein bridge to 3300 ohm each 29 Apply power to the circuit Observe the output of the summer mixer at pin 7 What do you see What You Did In the demonstration you mixed the sinewave output with the triangle wave The result is 550 Hz triangle wave on which is superimposed a 4800 Hz sinewave The 3300 ohm resistors increased the Wein bridge output from 1592 Hz to abou
228. ng at top speed You can add memory boards RAM disks print spoolers hard disks hardcards bubble memory graphics boards and monitors modems networks electronic mail mice light pens bar code readers voice input digitizers scanners optical disks PC Fax boards 80386 accelerator boards AT emulation and more Every chapter presents a hardware or software solution to an expansion prob Hits re Focal Conca s oem n PH k Sal KE CIRCLE 55 ON FREE INFORMATION CARD lem You learn how to select and use util ity software and hardware enhancements and implement other hardware enhance ments and implement other techniques to gain greater RAM more disk storage and better graphics You ll also find out how to choose a PC clone for maximum re liability and compatibility and make powerful applications programs like Lotus 1 2 3 and dBASE run faster and more effectively Best of all Supercharging Your PC has a do it yourself format you ll save money while you become a PC expert Retailing for 19 95 the book contains 358 pages and is available from Osborne McGraw Hill 2600 10th Street Berkeley CA 94710 Tel 415 548 2805 The One Hour Atari XL By Tricia Jordan Ph D Info Books has designed its One Hour Books to lead readers page by page from one easy friendly and successful experience with their computers to an other This book is an example of that user friendly technique Here s what you l
229. ngineer a chemist expensive way to 2861 H38O0120 wo o HANDS ON ELECTRONICS o FRIEDMAN ON COMPUTERS Continued from page 23 Ele homo C SP1 Special Projects 1 6 00 O SP4 Special Projects 4 Summer 1982 6 00 O SP5 Special Projects 5 Winter 1983 6 00 L SP6 Special Projects 6 Spring 1983 5 00 O SP7 Special Projects 7 Summer 1983 6 00 CL SP8 Special Projects 8 Fall 1983 6 00 C SP10 Special Projects 10 Spring 1984 6 00 CT 111 Hands On Electronics 1 5 00 O 112 Hands On Electronics 2 5 00 CL 113 Hands On Electronics 3 5 00 O 114 Hands On Electronics 4 5 00 O 115 Hands On Electronics 5 5 00 O 115A Hands On Electronics 6 4 00 CT 116A Hands On Electronics Jan Feb 86 4 00 1168 Hands On Electronics Mar Apr 86 4 00 C 116C Hands On Electronics May Jun 86 4 00 O 116D Hands On Electronics Jul Aug 86 4 00 C 116E Hands On Electronics Sep Oct 86 4 00 CO 116K Hands On Electronics Nov 86 4 00 C met Hands On Electronics Dec 86 4 00 C 117 Hands On Electronics back issues Hugs EE E 3 50 Write in issues desired TE C 152 8 Ball Satellite TV Antenna 5 00 C 107 Radio Electronics back issues 1987 3 25 C 106 Radio Electronics back issues 1986 3 75 Write in issues desired___ 1 O 105 Radio Ele
230. nic Way Secaucus NJ 07094 con Contemporary electronic civilization has reached the stage where microchips are going into toasters Is this a milestone or what Not just any toaster of course but the new Toastronic II from Robert Krups North America 7 Reuten Drive Closter NJ 07624 Uf the Starship Enterprise had carried a toaster it probably would have been the Toas tronic The company says the unit s microchip toasting technology 7 specifically a heat monitor insures uniform even toasting and makes manual resetting of the temperature level unnecessary The Toastronic also features a triple insulated outer housing rubber feet for secure footing and a cord storage bay for adjustable cord length Price 65 Here s a new entry into the electronic fashion accessory sweepstakes This one is called a Switch Radio inspired it appears by the success of the Swatch watch This AM FM radio is a palm sized transparent plas tic sphere rather resembling an old time diving helmet in miniature Red blue and yellow controls add color and the receiver can be used with either headphones not supplied or the unit s speaker of only mar ginally higher quality than those in the most budget priced transistor radios It s packaged in a see through plastic cube and comes equipped witn an antenna wire and a headphone adapter both of which use the same jack A semi charming novelty we were a bit surprised at its hefty price at Saks Fifth Avenu
231. nics Career through Independent Home Study Study materials carefully written by the Grantham College staff for independent study at home are supplied by the College Your technical questions related to these materials and the lesson tests are promptly answered by the Grantham home study teaching staff Recognition and Quality Assurance Grantham College of Engineering is accredited by the Accrediting Commission of the National Home Study Council as a degree granting institution All lessons and other study materials as well as com munications between the college and students are in the English language However we have students in many foreign countries about 80 of our students live in the United States of America Grantham College of Engineering H 10 10570 Humbolt Street Los Alamitos CA 90720 Please mail me your free catalog which explains your B S Degree independent study program Name LLL Age Address City State 4Zip INCLUDING s on Grace GADGET ness KS _ Volume 4 No 10 October 1987 A d CONSTRUCTION Grandpa s Antique Radio make a radio that reflects the early 1920 s Temperature Controlled Soldering Station helps prevent the destruction of delicate circuit elements Active Antenna For Better DX ing an active loop can dramatically improve long distance reception FEATURES
232. nser medium Refraction occurs when the incident wave enters different density region under going both a velocity and directional change with the amount and direction of change determined by the ratio between the densities of the two media Diffrac tion B occurs when an advancing wave front encounters an opaque object The shadow zone behind the object takes on a cone shape as waves bend around the object The diffraction zone between the shadow zone and the direct propagation zone is a region of weak signal strength DIRECTION OF TRAVEL B direction of that change is determined by the ratio of the densities between the two media If Zone B is much different from Zone A then bending is great In radio systems the two media might be layers of air with different densities It is possible for both reflection and refraction to occur in the same system Diffraction is shown in Fig 2B An advancing wavefront encounters an opaque object e g a steel building The shadow zone behind the building is not simply perpendicular to the wave but takes on a cone shape as waves bend Propagation Paths There are four major propagation paths surface wave space wave tropospheric and ionospheric The space wave and sur face wave are both ground waves but behave differently enough to warrant sep arate consideration The surface wave travels in direct contact with the Earth s surface It suffers a frequency dependent atte
233. nt That allows the output voltage to be set to some desired level With one set of input conditions the zener diode will be forward biased as any silicon diode and there fore the input will be very low typically 0 7 volts When the other input condition is reached the op amp output switches to the desired voltage level A common technique is to select a value approximately 5 volts that will allow the op amp comparator to readily interface with common TTL or CMOS digital circuits Virtually all op amp circuits are some variation of the basic circuits described above With different arrangements of input and feedback components in those circuits a literally unlimited number of useful circuits can be created The circuits to be described here will be described later as you implement each step of the experiment Parts Required In addition to a breadboard power supply a VOM and an oscilloscope you will need the following components 2 1458 dual op amp IC s Motorola or TI 2 0l jF capaci R 4 7V Vi Oly R E F CA if EE Fig 10 Using a zener diode as a feedback component causes the output to restrict its excursion thus outputting clearly defined pulses That is useful in digital circuits tors a Lu capacitor a l pF capacitor 2 3300 ohm 1 4 watt resistor a 2 000 ohm Va watt resistor 2 22 000 o0hm A watt resistor 3 100 000 ohm V watt resistor a 220 000 ohm V watt resistor a 10 000 000
234. nt Sources That brings us to the last component we will cons der the voltage controlled current source A generalized VCCS is shown in Fig 6 The current into node due to the VCCS Continued on page 102 Fig 5 A constant voltage source provides ACNAP with a way of computing the value of one node voltage by knowing another That simplifies the matrix and speeds up anelysis OCTOBER 1987 What s Inside Not So Solid Sender Global Touch Seiko s World Time Sensor Audio Independence High Fashion Medium Tech The Consumer Electronics Show Splish Splash Tick Tock Water Powered Watches The Videosender 2 AR Powered Partners 4 Transparent Onyx POLAROID SPECTRA ONYX Man ufactured by Polaroid Corp 575 Technology Square 9P Cambridge MA 02139 Price 280 We tested Polaroid s highly publicized Spectra System when it was first intro duced to the market GADGET Febru ary p 3 It was and is a highly ad vanced instant photography device a new age melding of electronics and opti cal science capable as Polaroid material always points out of making 30 com plex electronic focusing and exposure decisions within fifty thousandths of a second So how come only nine months later we are again featuring the Spectra Because a new model one introduced this spring does something gadgeteers have always been fascinated by This new Polaroid
235. nuation due to absorption into the ground Because the absorption increases with frequency we observe much greater surface wave distances in the 75 80 meter band 3500 4000 kHz than in the 10 meter band 29 MHz The space wave is also a ground wave phenomena but is radiated from an anten na many wavelengths above the surface No part of the space wave normally travels in contact with the surface VHF UHF and microwave signals are usually space waves There are however two compo nents of the space wave in many cases direct and reflected see Fig 3 The tropospheric wave is often lumped with the direct space wave in some text books but has properties that actually make it different in practical situations The troposphere is the region of our at mosphere between the surface and the stratosphere or about 4 to 7 miles above the surface Thus all forms of ground waves propagate in the troposphere But because certain propagation phe nomena caused mostly by weather con ditions only occur at higher altitudes we need to consider tropospheric propa gation as different from other forms of ground wave The ionosphere is the region of Earth s and is located 30 to 300 miles above the surface The peculiar feature of the ionosphere is that molecules of the air O and N can be ionized by stripping away electrons under the influence of solar radi ation and certain other sources of energy The electrons have a negative
236. o the AR s were harnessed to a Sony TC DMS field recorder and a small Panasonic boom box model FM115 The Panasonic was connected directly through the head phone jack while the Sony had dual output jacks Both delivered superb crisp sound when powered by the AR amps The bass of course was what was immediately noticeable and there was an absence of mid range boominess also The high frequencies were cutting and forceful without being too bright and the whole effect belied the low wattage rating to remain distortion free even at high volume The car unit was a midline Pioneer cassette player and we needed the DC adapter which unfortunately wasn t supplied by AR but was on hand any way The Partners were awesome when tested in the confined space of a Chevro let Nova providing a sound that was almost too bei for the road We found ourselves driving faster hoping the gen erator s power supply could keep up to the demands of the pre amps Finally we connected the Partners to a top of the line Sony Betamax Hi Fi VCR Again they performed admirably boosting MTV well into the listenable range and making even Doc Severinson sound good Again however we had to make do with our own speaker connect ors since the extension cables required were listed by AR under that odious cate gory optional Indeed that may be our only quibble with the Partners a unit like this sold to be compatible with
237. o0hm watt or V watt resistor a l1000 ohm potentiometer a 10 000 o0hm potenti ometer and a pilot bulb type 327 344 or 1869 You may need 2 silicon diodes 1N914 IN414 amp etc 2 4700 ohm V watt resistors 2 10 000 ohm watt resistors and a 47 000 ohm watt resistor if you can t find a suitable bulb You will need to solder some hookup wire to the potentiometers to use them on the breadboard Experimental Steps In these first steps you will demonstrate an integrator l Construct the circuit shown in Fig il Be sure to connect the supply voltage to pin 8 and the supply voltage to pin 4 Note that the input resistor is initially connected to ground 2 Connect a voltmeter between pin and ground to measure a positive DC output 3 Apply power to the circuit and note the output It should OUTPUT 7 49V HM Fig 11 This integrator takes the flat curve defined by the constant input voltage and outputs a voltage that increases as that area under the input curve increases be approximately zero volts 4 Now remove the input resistor from ground and connect it to the 9 volt power supply Observe the output You should note a slow rise in the output voltage The rise continues until the output limit of the op amp is reached at approximately 8 5 volts 5 Now move the input resistor to the 9 volt supply Again observe the output It should slowly decline to zero then switch polarity 6 Re
238. ocal coun ty and state law enforcement agencies in his area he frequently hears the term Red Direct used but he can t quite grasp its meaning He guesses that the Red makes it some sort of emergency code and wonders tf we can help with a more definite explanation What Fred heard is an expression used in many areas although Fred was con fused by the words What they re saying may sound like Red Direct but what they re actually saying 1s Read Direct a term used when one mobile unit asks the base station dispatcher to relay informa tion to another mobile unit If the unit who is to receive the relayed message overhears the message being given to the dispatcher he simply comes on the air and announces that there is no need to tie up the channel since the mes sage has already been read direct trom the other unit It takes on a whole new meaning when you realize that red and read may sound alike but they re quite different Fred isn t the only scanner owner who has gotten confused by words overheard on a scanner Many agencies especially ones such as the FBI and Treasury use numerous slang buzzwords in their com munications and those are often es pecially confusing A boat turns out to be a car a box is a van while a Louie is a left turn There are dozens of those buzzwords Once again we ve sadly used up the space allotted to us We invite you to send any questions comments photos an
239. oks about money and books about computers and books for owners of one spreadsheet for one particular computer Your Best Inter est is a book that explains financial spreadsheet calculations in a generic fash ion The information can be used with any spreadsheet on any personal computer Weishaar is an expert at making com plex ideas simple He shows you how to get any common spreadsheet program to do the mundane time consuming and error prone arithmetic of interest rates instantly and automatically But more than that you gain an under standing of how financial transactions ac similarities and differences of the two lan guages The comparisons demonstrate why Pascal is easier to write easier to read and easier to test and debug CIRCLE 52 ON FREE INFORMATION CARD tually work The book covers everything from calculating a percentage to deter mining the true cost of an adjustable rate mortgage In addition you ll learn about the tricks professionals use to take advan tage of unwary investors and borrowers And you ll see the long term effect taxes and inflation have on your personal wealth and what you can do about it Each chapter has real life exercises so you can see how the formulas work The soft bound book contains 172 pages and costs 9 95 from Info Books PO Box 1018 Santa Monica CA 90406 Tel 213 470 6786 Turbo Pascal For Basic Programmers By Paul Garrison Most computer programmers begi
240. oll free phone call away Ta first step is yours To find out more mail in the coupon below Or if you prefer call toll free 1 800 321 2155 in Ohio 1 800 523 9109 Well send you a copy of CIE s school catalog and a complete package of enrollment information For your convenience well try to have a representative contact you to answer your questions OF ELECTRONICS YOURS Today s world is the world of elec tronics But to be a part of it you need the right kind of training the kind you get from CIE the kind that can take you to a fast growing career in business medicine science government aerospace communications and more cialized training You learn best from a specialist and that s CIE We re the leader in teaching electronics through independent study we teach only electronics and we ve been doing it for over 50 years You can put that experience to work for you just like more than 25 000 CIE students are currently doing all around the world actical training You learn best with practical training so CIE s Auto Programmed lessons are designed to take you step by step principle by principle You also get valuable hands on experience at every stage with sophisticated electronics tools CIE designed for teaching Our 4K RAM Microprocessor Training Laboratory for example trains you to work with a broad range of com puters in a way that working with a single stock computer simply
241. olytic 35 WVDC Electrolytic get up then casually leave it at a friend s house and let him enjoy the benefits of early rising to meet the break of day A cloudy day might foul up the circuit but then nobody s perfect anyway Don t de spair if the Sun don t shine where your at because you can still make friends with the Electronic Wake up Call circuit by hiding it in a closet or in a desk or file cabinet or And when the light wakes the circuit up you will have made another C1 C2 1 LF 100 WVDC Mylar capacitor C3 C4 47 LF 16 WVDC Electrolytic capacitor D1 D2 1N914 silicon signal diodes LDR1 Light defendent resistor U1 555 oscillator timer integrated circuit Q1 2N3904 NPN general purpose transistor Q2 2N3906 PNP general purpose transistor R1 R3 4700 ohm 2 watt 5 resistor mw R 4 10K Q1 Q2 2N2222 NPN general purpose transistor R1 2200 ohm V2 watt 5 resistor R2 1000 ohm V2 watt 5 resistor R3 10 000 ohm 2 watt 5 resistor R4 10 000 ohm potentiometer Printed circuit or perfboard mate rials etching solution power supply or battery enclosure wire solder hardware etc good buddy Get the picture The operation of the Wake Up circuit in Fig 4 goes like this Acadmium sulfide photocell LDRI which is a light depen dent resistor is connected to the base and collector of an NPN transistor Ql When light hits LDRI the internal resi
242. ong time B Thousands of people have discovered this unique dimension in product ownership We d like you to discover it too For information on all our quality kits send NOW for your FREE four color Heathkit Catalog Send to Heath Company Dept 107 584 Benton Harbor Michigan 49022 pee 2 GR 9009 9 AC DC Color TV ONLY 249 95 The Heathkit ID 4001 Weather Computer which puts weather information at your fingertips With the press of a button you can instantly know tempera ture wind speed and direction and barometric pressure for the exact location in which you live For planning outdoor activities with greater assurance than ever And its all done with unsurpassed accuracy Long life IR LEDS act as sensors to make both the wind speed cups and the wind direction vane as sen sitive and as accurate as a costly laboratory instru ment While active solid state devices reliably measure indoor and outdoor temperatures all stored by a microprocessor for later recall Attractively designed the ID 4001 will give you extraordinary performance unheard of at sucha reasonable price 399 95 The IC 1001 Logic Analyzer is the perfect answer for trans forming a PC compatible computer or standard terminal into a versatile logic analvzer A top grade troubleshooter and design aid the compact Logic Analyzer includes 16 data lines plus clock and two qualifier lines checksum capability
243. ous fuse failures when no fault exists Fuse fatigue can also be caused by a constant cycling of high currents thru the fuse Those high currents could very well be normal but the fuse should be derated to handle that or a different type of fuse used as we shall see next Designers of commercial equipment have taken all of that into consideration so replacing a fuse in a commercial piece of gear is a matter of replacing a blown fuse with one of equal rating and type Fusing Characteristics The current and voltage rating of a fuse only tell us part of the story The missing rating is how fast the fuse takes to blow Since fuses are thermal devices and thermal characteristics UPRATING 20 ME A CT 0 S DOWNRATING 20 40 60 20 ger 20 C 40 C 60 C 80 C 100 C 120 AMBIENT TEMPERATURE Fig 1 A most important yet over looked characteristic of fuse operation is the ambient temperature As you can see as the temperature increases the rating of a fuse drops ABOVE RATED FUSE CURRENT 0 001 Di 0 1 1 0 10 100 1000 BLOWING TIME IN SECONDS Fig 2 Sometimes circuits are designed to run hotter than they are supposed to for certain applications For that reason slow acting fuses are needed since they tolerate overdrawn current for a length of time can not change instantaneously there is a time element involved when discussing fuses Generally those time elements are grouped
244. ow compare them with the schematic and the good channel Often tran sistor and IC component tests with accurate voltage meas urements will locate the defective component Single Channel Distortion Excessive distortion is usually caused by problems in the audio output circuits Switch the two speakers to determine whether the speaker or the channel to which it is connected is defective Take voltage readings of the defective channel and compare your findings to the voltage readings of the normal one sy r 253929 F a Uum m Sc A tet TER KAE 4 E E STK 0050A POWER OUTPUT 40V OPEN RESISTOR 40V After locating an open or leaky transistor or IC check each bias resistor It s best to check bias resistors while the suspected transistor is out of the circuit Often the shorted or leaky transistor may cause the bias resistors to open or burn An extremely warm transistor or IC may indicate that the component is leaky Take resistance measurements right across each bias resistor or from one point to common ground Fig 5 If both channels are distorted check the low voltage power supply and also check the semiconductors in each channel Damaged Speakers Speakers may be damaged by excessive power or im proper speaker matching Many expensive speaker systems can be damaged by excessively high volume at or near maximum or when high wattage amplifiers are connected to low wattage speakers A mid range speaker or
245. ply toss it out and get a new one The 741 requires a double ended plus and minus power supply for some of our applications So if you use the 741 be sure to modify the circuits accordingly Also watch out for the pin numbering Although most op amp s are pin compatible with the 741 there are some exceptions Basic Voltage Regulator Figure 1 shows a simple but effective voltage regulator circuit built around the 741 op amp The op amp U1 serves as a reference voltage source as set by zener diode D1 and resistor RI to control the base of Q1 which along with power supply circuits promotes 2861 H38O100 LD Kei HANDS ON ELECTRONICS eo eo Ul is set up in a feedback regulator configuration The reference developed across D1 is fed to the non inverting input of Ul At the same time a voltage proportional to the output voltage is tapped off a voltage divider network consisting of resistors R2 R3 a 10 turn trimmer potentiometer that s used to calibrate the output voltage and R4 The 10 turn potentiometer is preferred for the finest adjustment but an ordinary potentiometer can be used for experimentation or in less critical applications The sampled output voltage taken from the wiper of R3 is fed back into the inverting input of Ul If the voltage appearing at the inverting input equals that at the non inverting input the signal at the base of transistor Ql is 2 V But if the output voltage is incr
246. put at pin 6 is rectified by diodes D1 and D2 filtered by capacitors C3 and C4 The resulting DC output is applied to the base of transistor Q1 turning it Q1 on and thus the relay activating the load Oo TO TELEPHONE LINE O 1 5K P 3 po 2N4954 NN 01 1N645 TO TAPE RECOROER REMOTE CONTROL JACK Tn LL TO TAPE RECORDER MICROPHONE e NPUT JACK Fig 4 The tape recorder s switch terminals are connected to a Darlington pair consisting of Q1 and Q2 which are used to turn the recorder on and off The telephone s off hook voltage about 50 volts DC is divided over R1 R2 and R4 so that Q1 s base is negative enough to keep the recorder off Lifting the receiver causes the voltage to drop to 5 volts biasing the Darlington on which in turn hid the recorder When the telephone is off hook there s M RM 486 HSEOLDO He o HANDS ON ELECTRONICS eo o off on and off and will last forever as the drain on the battery is so slight His par ents freaked out when they saw it because they didn t know what it was Well what makes this my favorite cir cuit is that it blew them all away Can you picture an incandescent lamp blinking on and off like that Fred Conklin Brooklyn NY No way That s why recommend that people build this circuit into a little black box and mount a small pilot lamp
247. r daytime reception The weather Is given for numerous international air ports all over Europe from Athens to Shannon Reader Legate also says that the British Roval Air Force Volmet station gives weather for RAF bases plus the major United Kingdom civilian airports such as London s Gatwich and Heathrow plus Prestwick and Manchester Recep tion is usually good on 11 200 kHz daytimes and on 4 722 kHz at night Down the Dial ln answer to some recent questions about this monthly feature the times listed are in Coordinated Universal Time abbreviated as UTC which more veteran SWUSs may know as Greenwich Mean Time or GMT UTC GMT is a generally recognized time standard in international broadcast ing To convert to your local time sub tract 5 hours for EST 6 hours for CST 7 hours for MST or 8 hours for PST SWL s also use 24 hour clock time in which 0100 signifies AM UTC 1300 is PM UTC 2100 is 9 PM UTC and so on Frequencies in the following reports are in kilohertz kHz and are stations that other readers like yourself are hearing Your SW loggings can appear in this sec tion too 1f you ll just drop me a note with your information to Jensen On DX ing a Hands on Electronics 500 B Bi County Blvd Farmingdale NY 11735 Belguim 15 590 Belgian Radio and TV has its English shortwave service in cluding news and features at 1330 hours Czechoslovakia 5 930 Radio Prague
248. r dream The 625 s straight simple lines re flect Proton s past as a manufacturer primarily of studio grade equipment for professional use source of much of the brand s current consumer reputa tion This is what is called a table model at least in television terms and last year it was named best product of the year by Video magazine the editor of which called the 625 our fa vorite non console All black except for the green power switch on its front the 625 has built in stereo or can be used with several Pro ton loudspeaker systems The 3 3 pow ered speakers GADGET used in its tests are designed to flank the unit and are finished in the same low key black Equipped with an infrared remote control unit capable of access to 139 channels and cable compatible there are only five controls visible on the front of the monitor receiver itself Power channel selection two keys which tune up or down through the signal se quence volume keys TV video and antenna auxiliary switches are lo cated under the screen TV video accesses any of a trio of possible external component input systems Ant aux selects for RF signal sources such as cable decoder boxes some video games and VCRs Tastefully discreet lights above these controls and others indicate which se lections have been made Behind a door under the controls are the usual tuning adjustments verti OCTOBER 1987 ca
249. r soldering iron A problem solver but also a pocket drainer Since the price of commercially available units are rather high for the beginner or even advanced hobbyist the next best solution is to build this Temperature Controlled Soldering Station About the Circuit Figure shows the schematic diagram of the basic Tem Nerature Controlled Soldering Station As mentioned the unit is more or less pre made needing only to be outfitted with an AC plug and outlet with additional connections to the switch and the neon lamp That very basic circuit can be found in any of the commercially available units or in any book dealing with AC control systems The operation of the circuit is very simple Once the Temperature Controlled Soldering Station ts connected to the AC line capacitor Cl starts to charge through a variable resistor Ri Note that a diac triac combination torming what is known as a quadrac contained in a single TO 220 package can be purchased from electronic parts supply houses When the voltage across Cl reaches the breakover voltage of the diac around 30 to 40 volts the diac conducts dumping CI s charge across the gate of the triac triggering it into conduction The time constant for charging the capacitor is determined by the capacitor and RI a 200 000 ohm poten tiometer which is used as a rheostat Once the triac is turned on it continues to conduct until the AC current applied to its two main terminals MTI
250. r the power supply components Often you can hear the relay which might be controlled by power line DC source or a transistor energize when the off on switch is flipped If the unit contains a relay check to see if the relay con tacts close with the wiper top metal contact pulled down ward Energize the amplifier and make a voltage measure ment at the output of the transistors or IC s to determine if voltage is present Low or no voltage at the outputs may indicate poor or open relay contacts when supply voltage is normal When attempting to repair stereo amplifiers note whether each channel is protected by separate fuses Check speaker fuses when one channel has no output Suspect a leaky output transistor or IC when a line fuse constantly blows a ad The relay can be closed by pushing down on the metal contact with a pencil eraser and held closed by placing a piece of cardboard between the metal frame and contact assembly If the contacts close but the amplifier still doesn t work inspect the relay contacts and clean them up with a piece of emery board or a finger nail file Check the relay s coil windings and control circuits if the amplifier lights up but does not operate with the application of power Measure the resistance of the coil winding with an ohmmeter and replace the relay if the coil winding is open If the coil is normal check the bias on the transistors and or supply voltage to the IC s
251. rant II and quadrant IV see Fig 3 It s important to know the lead configuration so check the data sheet If no data sheet is available the gate can be distinguished from the main terminals with the aid of an ohmmeter Switch the ohmmeter VOM or DMM to the lowest resis tance range to promote sufficient current flow which must be greater than the holding current through the device under test Measure the resistance between all leads of the triac If the resistance between any two leads is low regardless of polarity you located the gate and MT1 making the final lead assuming a good unit MT2 Check the resistance between the first two leads the gate and MTI the lead MT2 The resistance between MT2 and either MTI or the gate should be at or near infinity without respect to polarity Now with one test lead connected to MT2 connect the other test lead to one of the leads which we now know have to be MT and the gate and touch MT to the last lead If the meter reading drops to some value substantially lower value than that obtained during your preliminary measurements the lead shorted to MT2 is the gate If not with MT2 still S01 The prototype was built in an old light dimmer case but could easily have been built on perf or printed circuit board 86t H38O100 Qe o HANDS ON ELECTRONICS e connected switch the connection of the other two leads and again short MT2 to the remaining lead Now while ho
252. rated with only one hand while the other must be away from the vicinity of the circuit e g in the pocket As an e 80 e 90 95 o o OFF Fig 5 To make the project easy to use the controls should be labeled as the author s with a calibrated scale like this one Note this scale may be lifted from the page and used to adorn the project housing or you can concoct your own added precaution remove all jewelry while operating the circuit Once the unit is assembled the testing procedure is easy First test for any short circuits with an ohmmeter connected between line and neutral cables of the line cord The ohm meter should show infinite resistance in either position of S2 Then switch SI to the off position and connect the unit to the AC outlet Switch S2 to the thru position and NEI should light Calibrating the unit is a straightforward task Simply con nect a load to the output and measure the voltage in the thru 100 V position Then flip S2 to the im position and calibrate the RI setting according to the voltage readings across the output terminals There are many more applications for this project than the one for which it is intended The circuit can find use in any part of your household It can be used to control any instru ment or tool that is AC powered regulate incandescent lights in your living room greenhouse or photo processing room Note that the circuit cannot be used to control fluorescent l
253. ration will produce both high fidelity stereo and video sound Other Bose Point Two loudspeakers are the 10 2 suggested retail 1199 and 8 2 949 floor standing speakers and the 6 2 and the 4 2 bookshelf systems 599 and 419 per pair respectively For further information contact Bose Corporation The Mountain Fra mingham MA 01701 Relay Servicing Tool Kit This may be the transistor age but re lays are still around so Jonard created a 15 piece precision relay tool kit con taining a carefully selected group of tools for use by the electronic and telecom munications industries The kit contains tools necessary for adjusting servicing and calibrating all types of relays CIRCLE 64 ON FREE INFORMATION CARD All tools are made of high quality car bon steel with heavy chrome plating for long life and top efficiency Dielectric tools permit adjustment and repair of live equipment without stopping oper ation the most practical and economical way to service equipment It comes with a leather zippered case engineered for max imum protection of each tool ensuring long lasting performance The case is compact for easy portability eleven inches long six inches wide The kit includes 2 spring adjusters armature bender spring tension gauge four way tool thickness gauge clean ing spray duck bill plier inspection mirror pen type contact burnisher 12 burnisher blades screw driver
254. rd and Referee Quick Start Card We used the latter to get started quickly we are about as impatient as our readers What the Persoft people claimed for Reter ee 1S what we discovered Referee can be called a memory man agement system comprised of three mod ules the core program which watches the activity in the computer s RAM the ap plications module which allows you to tell Referee about new applications or RAM make the composite monitor more reada ble Should you have some trouble that cannot be cleared up by reading the brief but comprehensible manual you can call Presoft s technical support staff during business hours Central time on week days For more information on Referee and for the name of the dealer nearest you write to Persoft Inc 465 Science Drive Madison WI 53711 or telephone 608 273 600 You could also circle No 81 on the Free Information Card 2 86t HABOLOO ech e GS HANDS ON MARKETPLACE WANTED INVENTORS AIM wants ideas inventions new products improvements on existing products We present ideas to manufacturers Confidentiality guaranteed Call toll free 1 800 225 5800 for infor mation kit BUSINESS OPPORTUNITIES HOME assembly Assemble PC boards for video accessories We supply materials No experience needed 7 50 per hour Send self addressed Stamped envelope to MICRON ELECTRONICS Box 4716 Akron OH 44310 HANDS ON ELECTRONICS ech CLASSIFIED AD OR
255. reat values that save you money You ll also discover convenient ordering with our TOLL FREE lines fast and friendly service plus quick shipment on the items you need All of this is in the new MCM catalog and we invite you to Take One For your copy with no obligation to buy call TODAY TOLL FREE 1 800 543 4330 In Ohio 1 800 762 4315 In Alaska and Hawaii 1 800 858 1849 MCM ELECTRONICS 858 E CONGRESS PARK DR CENTERVILLE OH 45459 A PREMIER Company SOURCE NO HO 07 861 H38O120 Ich w Zz CIRCLE 12 ON FREE INFORMATION CARD When you unpackage a Heathkit product you open up a special world a world providing a unique blend of achievement and fun 8 With your Heathkit prod uct you ll enjoy the pride of building it yourself and the confidence that it s built right Along with the convenience and assurance of knowing how to keep it running at peak performance B Plus you ll learn about new and emerging technologies For knowledge that gives you that added edge in your field 8 But most important with a Heathkit product you re buying from a company whose name is synonymous with quality and enjoyment From our easy to follow documentation to our renowned technical support we make sure your kitbuilding experience is fun and relaxing as well as rewarding B And when you re done your pride will be matched by the satisfaction of owning a product that you know inside out And that will last a l
256. revents dust and dirt from blocking light transmission to the CD player s optical system therefore eliminating distortions that result in audio drop out or skips in playback With the CDV about to be unleashed onto the market this new Discwasher product appears not CD Video Disc Cleaner a moment too soon Price 19 95 Coming in future issues of GADGET newsletter The Ultimate Portrait Chicago s Holicon has achieved a new level of real ism in holography one which may eventually have important implications for TV photography and motion pictures GADGET takes a three dimensional look into the future e Precision Workout Nike calls its new Monitor a perfect complement to any fitness program Besides measuring all sorts of workout variables the device talks to the user e Good Things in Smali Packages Panasonic s RN 36 Microcassette Recorder is a well designed easy to use tiny tape recorder We test the mighty mite and decide that small is beautiful e Photography in the Electronic Era GADGET tests brand new systems from a trio of well known camera manufacturers the Canon Eos 650 The Olympus Infinity and Fuji s HD M underwater camera Page 12 GADGET OCTOBER 1987 USING OP AMPS IN POWER SUPPLY LJANYONE wHo READS Hands on Electronics UNDOUBTEDLY knows that the op amp is one of the most versatile devices in all of electronics It shows up in countless applications But there is one
257. rges until the junction of RI and R2 is zero at which point the comparator switches applying the op posite polarity voltage to the integrator The integrator output then charges in the opposite direction until the comparator switches again The cycle continues to repeat The typical input and output waveforms are shown in Fig 16 An Oscillator In the following steps you will build and test oscillator and mixer circuits Do not disassemble the circuit now wired on your breadboard 20 Construct the circuit shown in Fig 17A Use a second Fig 15 Cycling the comparator output back into the integrator causes the integrator to alternately charge and discharge Further that causes the comparator to swing up and down and the cycle continues creating a series of triangle and square waves to be output 1458 dual op amp IC Be sure to connect the two supply voltages as indicated That is a Wein bridge oscillator that generates a nearly pure sinewave at a frequency that depends upon values of RI and C That frequency f is f 1 6 28RC If you cannot locate one of the light bulbs indicated in the parts listing use the alternate circuit in Fig 17B In either case the frequency of oscillation will be the same The output from the circuit in Fig 17A will be a cleaner sinewave than that from the circuit in Fig 17B 21 Apply power to the circuit Connect an oscilloscope to the output at pin 1 Adjust the potentiometer in the feedbac
258. rns for each single layer of cable Where more than one layer of cable is used the two turns and one turn are multiplied by the number of layers of cable Inductors LI through L4 may be connected in three dif ferent configurations by 3 position band switch SI to give three different inductance values and hence three different tuning ranges Those are Band with LI L4 in series 8 turns layer the highest inductance and lowest frequency range Band 2 with LI L2 in parallel L3 L4 in parallel and the two parallel combinations in series 4 turns layer medium inductance and a medium frequency range Band 3 with LI L4 in parallel 2 turns layer lowest inductance and highest frequency range That method provides three inductance values from the coil and always uses all the wire There are no dead end turns to absorb energy as with a tapped coil system As distinct from four separate windings LI L4 are ar ranged in a quadrifilar pattern That means that the first four wires at one end of the cable are the LI L4 beginnings and the last four wires at the other end of the cable are the LI L4 ends The remaining four wires on either end of the cable are cross coupled on the PCB to give the two turns per coil for each cable loop and the middle strands are routed via band switch S1 3 pole 6 position to give the three different series parallel turns arrangements previously discussed The quadrifilar arrangement of the windings was chosen b
259. rrents 400 above normal for several seconds They are naturals for use in circuits that have high starting or surge currents such as TV sets equipment with motors and high power audio amplifiers The graph in Fig 2 shows that after 2 minutes or so all the fuse types tend to act the same The Littlefuse catalog states that both a normal blow and a slow blow fuse will blow in 4 hours minimum for a 110 overload and in hour minimum for a 13596 overload Visual Inspection Examination of a blown fuse in the same strong light it took to read the end cap ratings can tell what circuit con dition took the fuse out A clean break in the fuse element would indicate a simple overload took the fuse out If the center of the fuse body is coated inside with the metal from the link chances are that a high current short exists that vaporized the fuse element In low current fuses where the fuse element is very thin sometimes only a quick check with an ohmmeter will tell if the fuse is blown or not Sometimes a fuse will visually check out okay but measure open on an ohmmeter Chances are that the fuse link separated at the joint with the end cap That is usually a fuse fatigue type of failure and chances are it was not caused by the circuit it is protecting Fuse Holders It is important that good contact between the fuse and the fuse holder be maintained The use of spring temper EE za berylium copper silver plated clips and holders i
260. rs waiting to be read That is to insure that an operator doesn t accidentally miss a screen of information The second line waits for any key to be pressed before it allows the program to continue On the Apple the second line of code can be replaced with a GET IN statement while he first line would require the use of a PEEK or POKE command Another way around using those lines would be to use an INPUT IN statement That would require that the RETURN key be pressed instead of allowing any key to be pressed before the program continues That command sequence is used in lines 1310 1580 3340 and 3610 in the program Technical Information To solve AC circuits ACNAP uses a technique known as nodal analysis A node is nothing more than a connection point between two or more components Nodal analysis is essentially an organized method of solving for the voltage of each node in a circuit by repeated application of Kirchoff s Current Law often denoted as KCL That law states that the sum of the currents exiting a circuit node must be equal to the sum of the currents entering that node That is Ka e kin Eq 1 To use nodal analysis one KCL equation is written for each node of a circuit except for the ground node The ground node is treated differently because it is used as a reference for all the other nodes of the circuit and therefore by definition its voltage is zero at an angle of zero degrees For a network with
261. s may cause high voltage at the speaker terminals in a direct coupled circuit Locate the amplifier s defective channel before Look for a tie wire mounted high at one end Then check under the chassis for poor solder connections Check the con tinuity of the tie wire on the copper side of the board poorly soldered tie wire may show a low resistance or open con nection It s wise to automatically touch up the soldering of all tie wire connec tions in the intermittent chassis Make sure you are in the correct channel when servicing a defective stereo amplifier Most large amplifiers are laid out with the left channel on the left when facing the amplifier from the front side Mark the correct terminals of transistors and IC components on the wiring side if not identified Darlington transistors may be checked in the same way as any transistor Individually check each transistor within the same envelope Be careful when checking voltages on the transistor or IC terminals so as not to short out an adja cent terminal Clean out the solder and rosin residue between the soldered terminals with a pocket knife after replacing a defective component clean the terminals with cleaning fluid and an old tooth brush After terminal cleanup take a low resistance measurement between the transistor or IC terminals If a short exists re move the excess solder and take another measurement Dou ble check each transistor or IC terminal with
262. s Ted s rendi tion of a Touch Switch which will control 9 volt DC loads of up to I100mA a great life span The circuit is built around a 4001 quad two input NOR gate with all gates connected to act as inverters Ulb to Uld are connected in parallel for a low imped ance output Those three gates along with Ula form a bistable multivibrator Touching the two upper contacts e g bridging the contacts applies a small current to the input of Ula causing its output at pin 3 to go low Ula s output is then fed to the bridged inputs of Ulb to Uld forcing its output high That high fed to the base of Ql causes the transistor to conduct pull ing its collector low completing a path to ground through the load circuit To reset turn off the circuit just touch the two lower contacts applying to the input of Ula causing its output to go low The low in turn causes the outputs of Ulb to Uld to go low turning off QI With QI turn off disrupting current flow in the load circuit and thus causing the load to cease functioning Well Ted your copy of the FIPS book is on the way Hope you enjoy it Door Slam Switch You want my favorite circuit You got it I come home at night walk across the 10 TOUCH PLATES REES 4 DUTPUT Q1 2N2369A e Fig 2 This Touch Switch which will comrol 9 volt DC loads of up to 100mA is built around a 4001 quad won gate U1b to Utd along with Uta form a bistable multivi
263. s a must if the currents are above 5 amps Heating at the fuseholder because of poor contact with the fuse will shorten fuse life Be sure to remove the fuse from the holder when soldering the wires to the holder to avoid unnecessary heating of the fuse itself Home Brew Projects The most common use of fuses is in the primary of the power supply of many of our home built projects That keeps the house from burning down when one of our pet designs decides it s time to see how fast it can make the power meter spin Figure 3 is a typical power transformer wiring diagram The fuse can be calculated by using the formula fuse 013xl x V where l is the secondary output current and V is the secondary voltage Assume that we have a 18 volt transformer that we will be drawing amp from l fuse 013x1x18 234 So use a 250 mA fuse That assumes a slow blow type fuse is used If a regular blow fuse is used the rating will have to be increased slightly to prevent the fuse from blowing from the surge of the initial turn on Always remember that the fuse in a piece of equipment was put there to protect it and you Bypassing it or oversizing the fuse may cause another component to fail and that may be more costly than the 50 cents for the correct fuse E A B INPUT NORMAL EE Pi INPUT d ei oi 4 SOLDER Gen OUTPUT OUTPUT Fig 5 A dual action slow blow fuse blows in one of two modes either the link melts
264. s of hook up wire for the ground and antenna ter minals Likewise solder another set of three inch length pieces to tie the varia hle capacitor to the perfboard Now set the perfboard aside and finish up the front panel EARPHONE JACK CONTROL Shafts of both controls go through the perfboard and top panel All parts of the radio are mounted upon the back side of the top panel which is fastened to the cabinet with flathead screws VOLUME zx Although an IC LS1 perfboard was used to mount all small parts a regular perfboard may be used The small parts are mounted into position as they are wired into the circuit Cabinet Construction The top and bottom panels are cut from hard tempered Masonite stock to look like a bakelite finish All holes were drilled into the top panel before applying two coats of black automotive spray enamel paint Cut out the 1 14 by 3 inch tube slot with a saber saw Sand down the rounded corners of the slotted area The two control holes must match exactly with the perfboard as the contro mounting nuts hold the per fboard to the top panel The perfboard is mounted e inch from the cabinet sides Draw the cabinet sides on the bottom side of the front panel so the pertboard holes will match those on the top panel Lay the periboard on the bottom side of the top panel and center the two holes for the regen and volume controls Cut the cabinet sides from a piece of scrap one i
265. s of simple PCB construction as comprehensively as possible Chapter 2 covers photographic methods of producing PCB s Chapter 3 CIRCLE 53 ON FREE INFORMATION CARD deals with most aspects of designing your own PCB layouts The book containing 66 pages costs 5 75 and is available from Electronics Technology Today PO Box 240 Mas sapequa NY 11762 A Practical Introduction to Microprocessors By R A Penfold If you re a good electronics hobbyist but the microprocessor is still a mystery to you then this text may help clear things up The purpose of the book is to provide a practical introduction to microprocessors by constructing a very simple micro processor circuit that the reader can actu ally build and experiment with and thus hopefully gain a clearer insight into this complex subject The completed unit is only intended as an educational aid and is unlikely to be usable in any actual applications but it can be built at quite modest cost and many of the parts should be suitable for re use when the unit has served its purpose The book is not intended for complete beginners at electronics lt is primarily aimed at those who have some knowledge of general electronics but have little or no understanding of microprocessors A Practical Introduction to Micro processors costs 5 00 and contains 90 pages from Electronics Technology To CIRCLE 53 ON FREE INFORMATION CARD day PO Box 240 11762
266. scoping MHz The 800 MHz band of course antennas an AC power supply plus a DC Regency Electronics Turbo Scan 800 features the standard VHF low and high bands UHF and UHF T bands accesses four amateur radio bands space research band VHF aero band the federal agency band and the controversial 800 MHz band which includes Cellular Mobile Telephone services technology that permits the scanning of board may be locked so the that which transmit on 136 77 and 137 77 CIRCLE 93 ON FREE INFORMATION CARD MD asks if we can root out the frequen cies used in the National Capital area by Metrorail the large public transit system there You came to the right place The Yellow Line in DC and the Red Line trains use 160 26 MHz The Yellow Line in VA as well as the Blue Orange Line trains are on 160 38 The yards and towers are on 161 235 MHz and test trains use 160 605 and 160 62 MHz Maintenance crews use 161 025 and the Metro Transit Police op erate through a repeater on 161 365 Monitors in that area nught also enjoy listening to some Coast Guard helicopter operations on 164 30 and 381 8 MHz and Search Rescue activities are found on 282 8 MHz Operations in the 225 to 400 MHz band can usually be monitored only on a select tew scanners unfortunately What Does It Mean Fred Worthington of Alabama writes to say that when monitoring the l
267. se difference in your electronics career Grantham offers this program complete but without laboratory to electronics technicians whose objectives are to upgrade their level of technical employment Since the field of elec tronics is so enormous opportunity for ad vancement is always present Promotions and natural turnover make desirable positions available to the man who is ready to move up Grantham College of Engineering 10570 Humbolt Street Los Alamitos California 90720 This booklet fer g FREE Booklet CLIP COUPON This free booklet explains the Grantham B S Degree Program m offered by inde paste on pendent study to those who work in electronics card and mail in envelope or lc Do You REALLY Want to Make More Money Yes it does take work and a few sacrifices to climb up the electronics ladder to where the bigger money is But if that s where you want to be then that s what you must do work harder at learning and getting the right credentials even if it takes a few sacrifices A B S degree and the knowledge that rightly goes along with it can give you powerful ladder climbing equipment in your search for suc cess in electronics The accredited Grantham non traditional B S Degree Program is intended for mature fully employed workers who want to upgrade their elec tronics careers INR ELECTRONICS Put Professional Knowledge and a COLLEGE DEGREE in your Electro
268. ssion to the 0 5 power i e x 0 5 That should give the same results 8 DEF FNMAG i J A function to determine the magn tude of a complex number in rectangular coordinates is de fined by that statement It is used in lines 3010 3030 and 3440 If your system does not support that function type those lines as shown below 3010 BXSQR A 1 1 0 amp K2 A 1 1 1 E K2 3030 TXSQR A K 1 0 2 A K I 1 2 3440 MAGXSQR A I N1 0 2 AN IS 9 ATN That stands for the arctangent function BEWARE Many versions of BASIC have that function but not all of them will return an angle that is in the correct quadrant You may have to check the signs of your numbers and force them into the appropriate quadrant 10 BEEP Used whenever an incorrect number is entered into the computer that statement simply causes the com puter to beep If your system does not support that com mand you might want totry the statement PRINT CHR 7 Another option would be to simply eliminate the command altogether 11 An apostrophe That is used to indicate a remark or REM statement Some versions of BASIC such as the Apple version require that REM be used instead 12 The last potential source of difficulty we wi consider are two lines used several places in ACNAP They are IN INPUTS IF IN THEN GOTO xxxx INS INPUTS IF IN THEN GOTO xxxx All the first line does is clear the keyboard input buffer of characte
269. stance goes from a very high dark value to a low light value supplying base current to QI turning it on The voltage across R1 produces a bias Fig 4 Electronic Wake up Call TONE FREQ ADJ R2 47 000 ohm 2 watt 5 resistor R4 47 ohm V2 watt 5 resistor R5 2200 ohm watt 5 resistor R6 50 000 ohm potentiometer R7 10 000 ohm potentiometer SPKR1 Smail 8 or 16 ohm speaker Printed circuit or perfboard mate rials etching solution power supply or battery enclosure wire solder hardware etc Fig 3 Voltage Multiplier C1 100 LF 25 WVDC Electrolytic capacitor C2 C3 10 pF 250 WVDC Electrolytic capacitor C4 33 yF 250 WVDC Electrolytic capacitor C5 01 yF 100 WVDC Mylar Capacitor D1 D2 1N4003 1 A 200 PIV rectifier diode Ui 555 oscillator timer integrated circuit R1 10 000 ohm 2 watt 5 resistor R2 47 ohm 2 watt 5 resistor T1 Miniature 8 ohm to 1K audio transformer Printed circuit or perfboard mate rials etching solution power supply or battery enclosure wire solder hardware etc that turns Q2 on which in turn supplies the positive voltage to Ul at pin 8 the positive supply input and pin 4 the reset input to operate the 555 audio oscillator circuit The circuit s sensitivity to light can be set via R6 a 50 000 ohm potenti ometer R7 sets the audio tone to the most undesirable sound The squarewave audio tone is fed
270. t sensors chemical and biological elec trodes oscillators and signal sources analog to digital conversion noise and noise reduction multiplexing digital data communication and power ampli fication and control circuits In his discus sions the author avoids extended mathematical treatment except where it is needed for full comprehension Circuit Design for Electronic nstru mentation Analog and Digital Devices From Sensor to Display contains 377 pages at a retail price of 49 50 from McGraw Hill 2600 Tenth St Berkeley CA 94710 Tel 415 548 2805 Advanced Graphics in C By Nelson Johnson Add graphics to your C programs and you Il add significant capabilities to your software With Advanced Graphics in C you ll be able to write graphics programs for the IBM EGA Enhanced Graphics CIRCLE 13 ON FREE INFORMATION CARD 1 ELECTRONIC COMPONENTS CATALOG yours FREE by dialing a 1 800 992 9943 In Texas 817 483 4422 Call Today for your FREE subscription to the 1987 Mouser Electronics Catalog Contains 176 pages featuring over 16 000 in stock quality electronic components PLUS Mouser s proven service and prompt delivery Outside U S A Send 2 MOUSER ELECTRONICS 2401 Hwy 287 North DISTRIBUTION e CENTERS CIRCLE 11 ON FREE INFORMATION CARD 2861 H389O0100 HANDS ON ELECTRONICS sch eo Adaptor the de facto standard for high quality
271. t 4825 Hz Your waveform should look like that shown in Fig 20 The mixer summer input and feedback resistors set the gain or amplitudes of the signals being mixed Such a circuit is used in audio mixers where sound from one or more musical instruments and voice from microphones are brought to gether Potentiometers on each input control the gain of each input Remove power from the circuit or play with it to your hearts content Next month we ll explore the use of high power semicon ductors such as SCR s So stay tuned same Hands on time same Hands on channel N Fig 20 The sum of the triangle and sine waves should have this appearance Note the amplitude of the triangle wave after amplification The sinewave was passed through without any gain leaving it puny by comparison 350 low cost of parts NEW IDEAS 42 PROJECTS COMPLETE PARTS LISTS ONE EVENING PROJECTS EASY TO BUILD Name Street Address City NEW IDEAS is packed with 42 practical cir cuits for the Electronics Experimenter and Proj ect Builder In addition to the headlight alarm the voltage freezer and the remote telephone ringer you get complete plans for a simple Tesla coil project that can generate 25 000 volts AC and draw one inch sparks Other interesting projects are a sound effects generator a crys tal tester a stereo remote control and much much more Each project was selected for its Please send and handlin
272. t radio propagation phenomena from DC to daylight well the ham bands any way The Electromagnetic Field Radio and TV waves are electromag netic EM waves exactly like light infrared and ultraviolet except tor fre quency The EM wave consists of two mutually perpendicular oscillating fields as shown in Fig 1A traveling together One of them is an electric field the other is a magnetic field In dealing with both antenna theory and radiowave propagation we sometimes make use of a textbook construct called an isotropic source for the sake of com parison and easy arithmetic An isotropic source assumes that the radiator 1 e an tenna is a very Uny spherical source that radiates equally well in all directions The radiation pattern is therefore a sphere with the isotropic antenna at the center As the wave propagates away from the source that sphere gets ever larger If at a great distance from the center we take a look at a small slice of the advancing wavefront we can pretend that its a flat plane as shown in Fig 1B We would be able to see the electric and magnetic field vectors at right angles to each other Fig IB The polarization of an EM wave is by definition the direction of the electric field Figure illustrates vertical polariza tion note that the electric field is vertical with respect to the Earth s surface If the fields were swapped then the EM wave ELECTRIC FIELD
273. te U S and possessions 28 00 Canada 33 00 ali other countries 35 50 Subscription orders payable In U S funds onty international Postal Money Order or check drawn on a U S bank U S single copy price 2 50 1987 by Gemsback Pubiications inc All nghts reserved Printed in U S A Postmaster Piease send address changes lo Hands On Elec tronics Subscription Dept PO Box 338 Mount Morns IL 61054 9932 A stamped Set addressed envelope must accompany all submitted manuscripts and or artwork or photographs If their return is desired shouid they be rejected We disclaim any responsibility for the oss or damage of manuscnpts and or artwork ot photographs while in our possession or otherwise Asa service to readers Hands on Electronics publishes available plans or intormation relating to newsworthy products techniques and scientific and technological developments Because of poss bie variances in the quality and condition of materials and work manship used by readers Hands on Electronics disclaims any responsibility for the safe and proper functioning of reader built projects based upon or from plans or Information published in this magazine Increase your knowledge about all aspects of electronics t f CREATIVE SOUND RECORDING 5 FUN TO BUILD PROJECTS FOR LEARNING ELECTRONIC THEORY E COMPLETE BUOG OF DSCILLOSCOPES 2635 19 95 2839 15 95 1532P 14 95 POWER CONTROL SOLID STA
274. ter on 3 975 KHz where unfortunately it often suffers interference from the British Broadcasting Corporation s BBC more powerful signals According to William E Mackie who heads the USAID technical advisory team in Monrovia the SW outlet is used to feed he national newscast to its remote micro wave stations in the bush The very briet shortwave schedule runs twice daily Monday through Saturday at 0700 UTC when it can be heard in North American and at 1900 UTC when it cannot Mon days through Fridays the news is followed at 0715 UTC by a half hour information program called Network Liberia Pro gramming is all in English VOA has one of its worldwide network of shortwave relay operations in Liberia and beams programs to Africa from a se ries of six huge 250 000 watt transmitters and two older 50 kilowatt units Programming is standard VOA fare hardly distinguishable from other Voice operations except for the occasional in dentification You can find the VOA s Liberian relay at various times such as between about 1600 and 2200 UTC Some frequencies to try include 15 445 15 600 17 870 and 21 485 kHz Radio ELWA is a religious broadcaster that has been operating from Monrovia for years on Shortwave lt is a rather substan tial broadcaster with a pair of SO kilowatt and two 10 kW shortwave transmitters ELWA programs in English French Arabic and several west African lan guages such as Ha
275. ther using this simple summing circuit The circuit will not only mix signals but amplify them as well That is useful for multi track audio Note that the minus sign means that the circuit inverts Op amp summers are used for algebraic addition and subtraction and for linear mixing of signals Figure 8 shows another popular op amp circuit the inte grator Here the feedback resistor is replaced with a capacitor With that arrangement the circuit performs mathematical integration You don t have to know integral calculus to use an integrator successfully All you have to know ts that when DC voltages are used at the input such as fixed DC levels or rectangular pulses the integrator acts as a linear ramp or sawtooth or triangle wave generator The formula below gives the output voltage in terms of the input Vo NAURCH Where R and C are used as shown and t is the time over which the circuit operates When used with sinewave signals the integrator acts as a low pass filter It also provides a 90 phase shift Integrators are widely used in function gener ators and wave shaping circuits Figure 9 shows how the op amp can be used as a com parator A comparator is a circuit that looks at two input signals and causes the output to switch from one state to the next when the two inputs become equal Fig 8 Operational amplifiers get their name from their ability to perform mathematical operations such as this integrator do
276. tput of 6 to 16 volts Voltage Multiplier The DC Voltage Multiplier circuit might just tickle your funny bone if you let your fingers do the walking through the circuit while the power is on as it Steps up the 12 volt supply to over 117 volts Aluuga the output voltage stands tall the circuit has very little umph in the out put current department and even a light load drawing say mA will drop the output voltage to about half The Voltage Multiplier can be used to supply a bias voltage to a high impedance circuit to ignite neon lamps for testing the reverse breakdown voltage of semi conductors or for any other application where a high voltage low current power supply is required Figure 3 shows the complete high volt age circuit Old reliable the 555 os cillator timer is used to generate the switching voltage AC to those in the know that feeds the primary of TI The AC voltage is stepped up by transformer TI and rectified in a two diode voltage doubler circuit to produce the 117 volts DC at the output The simplest way to make the output variable is to adjust the input voltage supplying power to the con verter circuit to obtain the desired output No I don t unfortunately own stock in any of the companies that produce the versatile 555 and didn t start out this month s Circus to feature an old friend in each of the circuits but experimenting with the device is too much fun to stop now so here s
277. ts Available In Stock eLC7 BURNING CUTTING CO LASER 20 00 e RUBA PORTABLE LASER RAY PISTOL 20 06 eTCC1 3 SEPARATE TESLA COIL PLANS TO 1 5 MEV 20 00 e 10G1 10N RAY GUN 10 06 e GRA1 GRAVITY GENERATOR 10 06 e EML1 ELECTRO MAGNET COIL GUN LAUNCHER 6 00 KITS e MFTIK FM VOICE TRANSMITTER 3 MI RANGE EE e VWPMSK TELEPHONE TRANSMITTER 3 MI RANGE Su e BTC3K 250 00 VOLT 10 14 SPARK TESLA COIL TIn e LHC2K SIMULATED MULTICOLOR LASER p e BLS1K 100 000 WATT BLASTER DEFENSE DEVICE TES e TM1K 100 000 VOLT 20 AFFECTIVE RANGE INTIMIDATOR bu p e PSPAK TIME VARIANT SHOCK WAVE PISTOL tg 5n e PTGIK SPECTACULAR PLASMA TORNADO GENERATOR 149 40 e MVPIK SEE IN DARK KIT 169 30 ASSEMBLED le PG7OH MULTICOLORED VARIABLE MODE PLASMA GLOBE 7 425 00 e BTC10 50 000 VOLT WORLD S SMALLEST TESLA COIL 44 3 e LGU40 1MW HeNe VISIBLE RED LASER GUN 299 44 e TAT20 AUTO TELEPHONE RECORDING DEVICE 24 50 e GPV10 SEE IN TOTAL DARKNESS IR VIEWER 299 5n e LIST10 SNOOPER PHONE INFINITY TRANSMITTER 169 50 e IPG70 INVISIBLE PAIN FIELD GENERATOR MULTI MODE 74 50 CATALOG CONTAINING DESCRIPTIONS OF ABOVE PLUS HUNDREDS MORE AVAILABLE FOR 1 00 0R INCLUDED FREE WITH ALL ABOVE ORDERS PLEASE INCLUDE 3 00 PH ON ALL KITS AND PRODUCTS fp ie POSTAGE PAID SEND CHECK MO VISA MC IN US FUND INFORMATION UNLIMITED P 0 BOX 716 DEPT HO AMHERST NH 03031 861 Y3EOL9D0 Gu HANDS ON ELECTRONICS
278. ts as well as discrete components such as transistors and diodes Send for FREE Catalog Send the coupon today for NRI s free catalog that gives you all the details about the Electronic Design Technology course If the coupon ts missing please write to Your hands on training includes all this the unique NRI Circuit Designer a soideriess bread boarding system you bulld and use for circuit design prototype construction component evaluation and testing the NRI Model 2500 10 MHz tnggered sweep oscilloscope invaluable in eictronic trouble shooting a T30 calculator for fast accurate computations and 2 digit hand held digital multimeter you learn to use as professionals do fo perform electronic tests and measurements If you write to us we ll tell you how you can help stop abuse of our public lands Write Take Pride in America P O Box 1339 Jessup MD 20794 BAD GUYS ABUSE PUBLIC LAND GOOD GUYS SAVE IT Sa Send coupon today for free NRI catalog Mares IOOL OF ELECTRONICS McGraw Hill Continuing Education Center 3939 Wisconsin Ave Washington D C 20016 Please send information about NRI training in Electronic Design Technology Se S NRI School of Electronics 3939 Wisconsin Avenue Washington DC 20016 2861 H38O100 RO HANDS ON ELECTRONICS e 7 ARS Ae AAA ai By Homer L Davidson Make and enjoy a radio that refle
279. tu 4 T 745 19 2N 3066 eec AN d 3 n Aaf 1 2 3904 E I 74181 E KI VU Diego KU Du 15 74S 182N 4174 J418AN 45 1 amp 8 TAN 1 amp 1 GU 7451 A 74172m 3A 1N Pants sO QUALITY 74S 15N e x ot n L ES e enn 5 ge enit X Wil J 310 DISC t e 7 CAPACITORS E6X EX JEJE TT KKK J4 V SN P4 VIP MI 93418 N GM J4161N MIEN J4164N 9 MIN MIN zw y MRA MtB48N M he M dus 3 SSRES 2 2 PEB 84285 43 TI d LE R u TT TETAY aAMGeEtuiw oF 71 POPvLAS VALDIS Anal awaye d AN HA HIRIN 74 ie Metallized Polyester c apacitor s MSIN TAS TON 745 Bh 45 185 J4 194 KO 3 45 197NN Fa SMON EFI LL alt tet Pet Ge Jum d SRRRR 74 Vs NPN 4 9B JA 1 WIN 7475 M 1EAN S siasah AM TN 74 g t Sib AT EF E ELA ET E TEE s LE GEZ keet aS PIN SEBERO MT 19 4 men 17 1 sSaP Bal ioawasxtes ca aSake eco ELITASI GbeRRRSRRS Meta EEFE I E i CIE a BOS N KAN o m Se 8 1 ve 8 fEZESWZTRSRITTITTITTT PI DIL Mr ih Ge aa 74 506 TTL anri P Pai SOON 74 285 BSBEERBRRESEEEEESRESEBEEBBREBRHESEBEEESASEEBRERRERBESSSESBSEESENZEMSE Jan c ao Ara 45 14 MMC AS BA An C454 74 SOIN PaL SOJA t i SO 41 Shi Ia Sg Mi S08 MA S ON 4 11N KIC SESSA TT PES ee eee eee ive L d bl SV r ba EL EK ILR KE TAAT of 9 POPULAR VALUER PANASONIC V SERIES Stated B
280. uctors CONDUCTOR 4 INITIAL NODE FINAL NODE 2 VALUE Mhos 0 5 Enter number of capacitors CAPACITOR INITIAL NODE 2 FINAL NODE 3 VALUE F 0 0067 II 1 Enter number of inductors a m INDUCTOR INITIAL NODE 0 FINAL NODE 3 VALUE H 0 1 Enter number of ICSs mmm emm ICS i INITIAL NODE The tail 0 FINAL NODE The point 2 MAGNITUDE Amps 1 5 PHASE ANGLE Degrees 45 Enter number of VCCSs 0 Enter number of IVSs emm emm emm emm emm emm NEGATIVE NODE 0 POSITIVE NODE MAGNITUDE Volts 10 PHASE ANGLE Degrees 0 CALCULATING PLEASE WAIT THE NODE VOLTAGES ARE V 1 10 jO volts JO SIN 100t 0 V 2 6 954887 2 253797 volts 7 310955 SIN 100 t 17 95541 V 3 8 175043 j 2 6492 volts 8 593578 SIN 100 t 17 95541 Press any key to continue IVS Would you like to analyze another circuit Yes or 2 No Your choice The next circuit we will run through ACNAP is shown in Fig 4 That two node circuit is operating as follows w 500 Hz I 3 Sin wt 150 Fig 4 Even circuits with voltage controlled current sources such as opamps can be analyzed by ACNAP The polarity of the control voltage is important for proper analysis by the program so be careful Note that the current supplied by the VCCS is controlled b
281. under short circuit conditions A or the solder blob melts due to continuous overload Mode ORS 900 Power Amplifier Fjer D zh Bart T Led nn S ege t A You don t have to be an audio service technician to troubleshoot and repair malfunctioning audio amplifiers 3y Homer L Davidson ONE might think Don t let the various components on the printed circuit board intimidate you nor should you be dissuaded by expensive test instruments They re not really a necessity If you check the right area and know what to look for you can locate the most difficult audio problem with nothing more than a pocket VOM or DMM That s because the symptoms displayed by the amplifier are like a road map And by following things through you re bound to get to the root of the problem Qs HIGH WATTAGE AMPLIFIERS ISN T AS DIFFICULT AS An Ounce of Prevention As when attempting any repair it is wise to take a few moments to institute some precautions in preparation of the task at hand For example always keep the volume down when making critical voltage measurements Be extremely careful in measuring voltage on the power output transistors and IC s so as not to short out any of the elements Be sure to load the speaker terminals Simply attach a couple of resistors 10 or 20 ohm l0 watt units to the speaker terminals as shown in Fig And let s not forget to remove the power cord from the AC outlet or at t
282. us that second chancc The fact that the Underwriters Laboratories will not allow a manufacturer to sell equipment that does not have some sort of over current protection may also have something to do with it Consider what happens to a circuit when it is not fused and a fault develops You might end up with components other than the faulty one destroyed circuit boards damaged possi bly even a fire caused by overheated components So the use of some kind of over current protection is almost mandatory At this point it should be acknowledged that a circuit breaker can perform the same duties but that is another discussion For now we will concentrate on fuses Whether you are buying replacement fuses or trying to decide what type fuse and fuse rating to use in your next design a little knowledge of fuseology will help and that is what this article is all about All fuses have a specific current rating voltage rating and fusing characteristic When those factors are understood and correctly applied the circuit is provided with safe trouble free protection Physical Size The fuse industry has always tried to provide some sort of interlock so that the correct fuse is always used to replace a blown one Household screw in type fuses have a different thread pitch on the base for the various current ratings so only a fuse with the correct current rating can be used Cartridge type household fuses come in different lengths and diameters
283. usa Ibo and Fultulde Look for this one in English trom 0600 UTC on 4 760 KHz It is also scheduled from 0700 UTC on 11 830 kHz and from 0825 UTC on 6 070 kHz ELBC the Liberian Broadcasting Svs tem also in the capital of Monrovia ot fers something a bit different to the SWL s ear West African commercial radio It has a 50 kilowatt shortwave transmit ter and can be best heard on 3 255 KHz beginning at 0530 UTC With some effort good reception conditions and a bit of luck SW listeners in many parts of North America may manage to log all tour of the Liberian shortwave outlets Book Look One of the most commonly asked SWL ABBREVIATIONS BBC British Broadcasting Corporation CST UTC 6 hours DX long distance over 1000 miles DX ing listening to shortwave broadcasts EST UTC 45 hours F frequency modulation p modulated kHz kiloHertz 1000 Hertzs or cycles kw kilowatt 1000 watts LRCN Liberian Rural Communications Network MST UTC 7 hours PST UTC 8 hours RAF Royal Air Force RDI Radio Database International SW shortwave SWL s shortwave listener s TV television UTC GMT Universal Time Code Greenwich Mean Time VOA Voice of America VHF very high frequency questions is where should tune to find a particular station and when And one of the best answers to that question in my view is the annual Radio Database Inter national volume which is really a Pass port to Worl
284. ut an exhaustive rundown of the acres of products at the Consumer Electronics Show In coming issues we ll be testing some of the prod ucts described above as well as many which were shown at CES but which went unheralded here Besides given the characteristics of the Chicago exhi bition this year its most important de velopments will probably be reflected in trade economic journals i e the Yen vs the dollar and given pending leg islative proposals regarding DAT by political news coverage A C Z GADGET Page 9 2861 H38O01090 on nn HANDS ON ELECTRONICS an o tacted us to say that the firm offers an even more compact version the Pocket Watch model CT 311E This model which features a 3 diag onal LCD screen and AM FM stereo radio measures 4 3 high 1 6 thick and 3 6 wide The color TV Panasonic says offers outstanding picture clarity and a wide viewing angle as well as sharp intermediate colors What the company dubs slide rule tuning is said to simplify the locating of stations Power is from six AA batteries or the CT 311E can be used with an AC adapter The batteries are good for a maximum of five hours of viewing time The unit s auto search tun ing helps receive stations clearly Price To be announced weg Bits L Pieces Right after we reported last month on the mini size Pocket Watch TV EN ux 5 the CT 333S Panasonic 1 Panaso
285. ven in Fig 5 the gain is Gain 100 000 10 000 II The third most popular circuit is called a follower The output is connected directly back to the inverting input while the input signal is applied to the non inverting input see Fig 6 The op amp follower is like an emitter follower in that it has very high input impedance low output impedance and unity gain The output voltage is equal to the input voltage in phase and amplitude The value of the follower is that it ts a power amplifier and therefore can drive heavy loads Fol lowers are used as buffers between high impedance and low impedance circuits without affecting the signal phase or amplitude Another common op amp circuit is the summer shown in Fig 7 The configuration is the same as that for an inverting amplifier except that multiple input resistors are used In that way two or more input signals can be algebraically added together Each input signal is multiplied by a gain factor that Fig 6 This simple voltage follower will isolate two circuits to prevent problems with loading and phase shifting of the input signal Although the circuit doesn t amplify the signal it is very useful and sometimes a must is simply the ratio of the feedback resistor to the input resistor values The following formula gives the complete output voltage expression based on the inputs and circuit values Vo V R R VARR V R R Fig 7 Signals can be added toge
286. verse the voltmeter leads and measure the output voltage It should eventually rise to about 8 5 volts 7 Connect the input resistor to ground Take a short piece of hookup wire and touch it to the two leads of the Lut capacitor That will discharge the capacitor 8 Using a stopwatch or the sweep second hand on your watch time the next operation Move the input resistor from ground to the 9 volt supply At the same instant start your watch Let the circuit integrate for 5 seconds then disconnect the input and connect it to ground Note the output value and record it below Vo after 5 seconds volts Now remove power from the circuit Review of Steps 1 8 In the above steps you demonstrated an op amp integrator With a fixed DC input the output is a slow linear ramp as the capacitor charges and discharges With a negative DC input the output ramp is positive With a positive input the ramp goes negative That means that the circuit is an inverter Figure 12 shows typical inputs and outputs The integrator keeps on integrating until the output limit of the op amp is reached Once the feedback capacitor is charged it remains charged even if the input voltage is zero The capacitor stores the last value it sees That is an advantage in some circuits but in INPUT RUE A OUTPUT 0 n o NEBATIVE B 5V 7 SATURATION LEVEL INPUT deeg EN POSITIVE 1857 4 SATURATION OUTPUT MU E LEVEL Fig 12 Of course the
287. volts Fig 13 In this comparator circuit the non inverting input is used to receive the reference voltage and the inverting input as the signal being tested 12 Next rotate the potentiometer slowly while observing the output voltage At some point the output will switch Stop turning the potentiometer at that point Note the output voltage Vo and the input voltage V at pin 6 Vo __ volts _ volts 13 Compare the input voltage to the reference voltage at pin 5 Turn the potentiometer above and below the switching point and note how the output swings between the two limits 14 Remove the potentiometer from the circuit Connect your integrator output pin 1 to the comparator input pin 6 Your circuit should look like that in Fig 14 Be sure that the 10 megohm input resistor is initially grounded Short the feedback capacitor to discharge it and connect your VOM to the comparator output 15 Now touch the integrator input resistor to 9 volts At the same instant start your stopwatch Observe the com parator output voltage As soon as the output voltage switch es stop the stopwatch and note your time below Time _ seconds 16 What factors influence the time Review of Steps 9 16 In Steps 9 13 you demonstrated the operation of a simple comparator The reference input is derived from the two 10 000 ohm resistors in a voltage divider that sets the refer ence input to one half the supply voltage or 4
288. volume control to zero and keep the 20 ohm resistor connected to the speaker terminals when one chan nel has high DC voltage at the speaker terminals Notice if the output transistors or C s become extremely warm in the defective channel after five minutes of operation Next test each transistor out of circuit for leakage or open conditions in the output circuits see Fig 6 Replace transistors and IC s that appear excessively warm While the transistors are out of the circuit check the bias resistors and diodes with the DMM Take critical voltage measurements on each transistor and IC Check each lead and tie wire within the circuit for normal continuity with the low ohm scale of the DMM Burned resistors or leaky tran sistors and IC s can cause numerous DC circuit failures Make sure that all voltages of the negative and positive sources are normal Remember a broken i Critical voltages on the suspected power IC may indicate a leaky IC component or unbalanced DC circuit Interchange the two output IC components in both channels to see if it is defective when you do not have a replacement on hand 2861 H380120 j o 38V Fig 6 Any defective component within the DC amplifier circuits can result in a high DC voltage presence at the speaker terminals It s a good idea to check the speaker terminals for DC voltage before connecting a replacement speaker 3 AMP FUSE TO CN SPKR 0508 23 5V OARLINGTON
289. wan ese device called a Videosender It s supposed to do wirelessly what the VCR Rabbit and the Multiplier do with cables namely send audio video sig nals from a VCR or television to an other TV of transmitting signals to locations path for the device s signal The instructions call it a miniature with a 200 foot range to 165 feet if But even in a suburban location the wireless video transmitter which util the distance between the sender and transmission was far from a total suc izes the UFH frequencies 14 26 to the receiving TV is completely unob cess The received image was full of conveniently transmit TV signals to structed by walls or other obstacles horizontal red lines indicative of inter remote television locations within a Our first test conducted at the ference even in a less congested loca 200 foot range The Videosender it GADGET office was a complete flop tion So the Videosender worked self is a black box about the size ofa We followed the simple instruction but not very well small tape player equipped with a tele sheet but nothing happened on the re Although not engineers we suspect scoping antenna a power switch with ceiving set tuned to UHF channel 15 that to make this device work would red signal light audio video jacks beyond some possibly Videosender require enough extra engineering and three fine tuning screws and a jack for originated interference This failure we
290. woofer may be damaged by a defective direct coupled amplifier because there is no blocking capacitor to prevent the DC component of the audio signal from reaching the speaker Suspect too much power has been applied to the speaker when the voice coil is blown loose or frozen against the STEREO POWER AMPLIFIERS LEFT CHANNEL RIGHT CHANNEL CH n TOH a 1 AOWERA Pace j TIVE me is gasi 3 HEAT SINK Fig 5 Check the base emitter bias circuits for open or burned resistors in the power output IC and transistors section of the amplifier when the output audio is weak and distorted The open resistor R263 shown here in the power output circuit from a Pioneer model SX 780 caused excessive distortion TO SPEAKER center magnet The voice coil can be zapped if a DC voltage is applied to the speaker terminals Always check for DC at the speaker terminals before replacing a speaker It makes no sense to correct the symptom and neglect the cause Servicing DC Circuits Although most speakers are fuse protected DC voltage found at the speaker terminals may destroy the voice coil With a 10 or 20 ohm resistor connected across the speaker terminals to simulate the loading effects of a speaker test for DC voltage at the speaker terminals The audio output circuits are unbalanced when a high DC voltage is found at the speaker terminals With normal DC circuits the voltage Is zero at the speaker terminals Lower the
291. xial plug and a length of cable are supplied with the kit For receivers with only a telescopic antenna and no exter nal antenna input a twisted pair from Techniloop with two alligator clips for connection to the antenna and earth will be required The earth is not strictly necessary but will help on the lower frequencies Receivers with existing ferrite rod antennas for the broad cast and or LF bands present more of a problem If there is no provision for an external antenna or Earth then a two or three turn winding may be added to the rod and brought out to a connector or terminals on the back of the set Note that when using the loop simultaneously with a ferrite rod you will need to keep both correctly oriented towards the station The edge of the loop should be pointed in the direc tion of the station while the ferrite rod should be broadside to the station for maximum signal pickup Small hand held radios may simply be placed or held near the loop antenna Orient the radio so that the end of its built in ferrite rod antenna points towards the center of the loop Note that in that case the coupling is inductive and the loop needs only to be set for passive operation Tuning the Loop With the receiver set to a vacant spot around the center of the band of interest switch the loop to active and set the output level control to maximum When the loop tuning coincides with the receiver tuning there is an unmistakable increase in act
292. y experiment It had little loss and high Q at the high frequen cies yt 9v PLUG PACK Inductor L5 is a single turn per layer of cable which is used to provide a low impedance output in the passive loop mode The loop is tuned by C4 which is a polycon variable capacitor Most of the small polycons have maximum capacities of around 160pF antenna section and 60pF oscillator section totaling only 220pF with both sections in parallel The capac itor used in the Techniloop has a maximum value of 470pF and has been obtained specially for the project Unfortunately the more common smaller units just do not give enough tuning range for overlap between the three bands for any given loop size The Active Circuit Passive operation S2 in position 1 gives good results under most conditions and uses no battery or other power However for best pertormance a JFET bufter amplifier is included That is simply a source follower which butters the loop and allows close to the full unloaded loop output to be delivered into a typical low impedance receiver input Buftering the coil in this way also significantly increases the selectivity The effective power gain provided by the buffer is very useful especially for DX long distance work with very weak signals Output Level Control An output control is used to adjust the loop output in both the passive and active modes and has proven indispensable in practice The AGC automatic g
293. y shift metal locators such as a simple beat frequency oscillator BFO a BFO with selective filter detec tor or a single oscillator high selective filter locator circuit balanced inductance locators transmitter receiver circuits for both small and large objects and unusual metal locator circuits You ll learn which types of compo nents to use to achieve greater or lesser sensitivity what types of circuits to build to locate objects at shallow or greater depths even how to develop a special lo cator geared to finding buried treasure Best of all each one of the projects in cluded are tested and proven original de signs by the author not just duplicates of commercially available kits The 114 page book retails for 9 95 from Tab Books Inc Blue Ridge Sum mit PA 17214 Tel 717 794 2191 Assembly Language Subroutines for MS DOS Computers By Leo J Scanlon Do you want over 100 useful sub routines to put extra programming power at your fingertips Let your fingers do some walking through these pages This collection of practical easy to use subroutines is exactly what is needed for performing high precision math convert ing code manipulating strings and lists sorting data displaying prompts and mes sages reading user commands and re sponses working with disks and files and doing countless other jobs Models are also included that provide the boilerplate the assembler requires for use in the pro grams an
294. y the voltage VC which is the voltage between node and node 2 Enter the number of nodes in the circuit not counting the ground node 1 25 2 Do you want to enter the frequency in Hertz or 2 Radians second Your choice Frequency Hertz 2 0 Enter number of resistors INITIAL NODE FINAL NODE 2 VALUE Ohms 10 Enter number of conductors 0 Enter number of capacitors INITIAL NODE FINAL NODE 0 VALUE F 0 015 Enter number of inductors 0 Enter number of ICSs 0 mmm o oo om emm emm emm lt eme emm ICS INITIAL NODE The tail FINAL NODE The point 0 MAGNITUDE Amps 3 PHASE ANGLE S Degrees 150 Enter number of VCCSs INITIAL NODE The tail 0 FINAL NODE The point 2 MAGNITUDE Amps volt 0 CONTROLLING NODE Positive 1 CONTROLLING NODE Negative 2 Enter number of IVSs 0 CALCULATING PLEASE WAIT THE NODE VOLTAGES ARE V 1 2 093915 j 1 748948 volts 2 728241 SIN 12 56637 t 39 8704 V 2 3489858 2914913 volts 4547068 SIN 12 56637 t 39 8704 Press any key to continue Would you like to analyze another circuit Yes or 2 No Your choice 2 Other BASIC Dialects Below twelve different commands and programming tech niques used in ACNAP are listed and explained If you are not using the MICROSOFT implementation of BASIC those are the statements you might have to
295. ysis and THINGS TO DO WITH YOUR LC MERE ee i Fee TE WE CIRCLE 54 ON FREE INFORMATION CARD business management from game play ing and hobby use to scientific and edu cational utilization Best of all the guide reveals numerous techniques for using the Amiga in a huge variety of practical and just for fun ways to forecast weather to help youngsters make better grades to calculate camera settings to keep a business on the road to better profits for technical applications and of course to play games It contains lots of ways to save time and money even ways to use it to make money it s a book that ll inspire the reader to come up with stil more ideas The authors have provided all new commercial quality programs for finan cial business and educational applica tions unique games a library of computer specific utilities and sub routines sound and graphics printouts flowcharts diagrams and a wealth of il lustrations Containing 208 pages the book retails for 12 60 from Tab Books Inc PO Box 40 Blue Ridge Summit PA 17241 Tel 717 794 2191 Supercharging Your PC By Lewis Perdue We all know the PC has a wide variety of expansion options but which is right for you This book tries to make the list of choices clear Supercharging your PC is easy with this do it yourself expansion guide for your IBM or compatible PC Perdue shows you tricks you can use to get your PC performi

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