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Identifying Defective Motors

1. SAN THe Corra 5 12 15 CERTAINLY A handful of scanner Sporting a low end price it allows you to program 16 chan nels of your choice into the unit and watch it scan through the entire batch of them in only one second The SR 12 5 frequency range is most respectable covering the 30 to 50 MHz VHF low band the 118 to 136 MHz VHF aeronautical band the 136 to 174 MHz VHF high band and the UHF spectrum straight through from 406 to 512 MHz That s no less than two ham bands and the most popular public safety industrial federal aeronautical and maritime bands Just because the scanner sells tor less than 5200 don t think it s a bare bones unit not at all Some of the features offered in the Cobra 12 include rapid search scan at 25 frequencies per second full programmability with a direct access keyboard single channel manual step through channel delay and lockout priority channel backlit LCD display and battery power indica tor The accessories supplied with the Cobra SR 12 are the rubberized anten na AC power supply and battery charger earphone and carrving case 2 The scanner has an IF selectivity of 50 dB at 25 kHz and RF sen sitivity range of between 0 3 and 0 8 i V for 12 dB S N depending upon the band as with most handheld scanners For more information on the 55 12 write to Cobra Consumer Electronics Group Corp 6500 Wes
2. CALL FOR AVAILABILITY Output Quantity Channel SUBTOTAL Shipping Add 3 00 per unit COD amp Credit Cards Add 5 TOTAL California Penai 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 Name Address City Phone Number COD Exp Date State Zip Cashier s Check Acct Money Order Mastercard Signature FOR OUR RECORDS DECLARATION OF AUTHORIZED USE the undersigned do hereby deciare 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 cable Company officials accordance with all applicable federal and State laws FEDERAL AND VARIOUS STATE LAWS PROVIDE FOR SUBSTANTIAL CRIMINAL AND CIVIL PENALTIES FOR UNAUTHORIZED USE Dated Signed 818 716 5914 No Collect Calls 818 716 5140 Pacific Cable Company Inc 73257 RESEDA BLVD DEPT H10 RESEDA CA 91335 Copyright 1987 PACIFIC CABLE CO INC 8861 H389O100 HANDS ON ELECTRONICS eo Electronics Library ishing documents Novices as well as expe rienced Word users will find the alphabetical reference section to be a quick convenient way to locate commands and features Each entry begins with a description and then explains the steps followed to use the com mand or featur
3. Cordless Tone Generator 8861 H380120 z i o N on Gizmo Bytes Gamma Tuner o 2 2 9 Electronic Auto Compass lt 54 Page 8 GIZMO Packtronics Video Light Meter If you ve recently made the switch from photography to videography and miss your old accessories and equipment Svstems Inc 7200 Huron Dr Dexter 48130 has a product worth noting From the firm s Packtronics division it s a Video Light Meter LX 1 Most camcorders have some kind of light level indicator system built in but Photo Systems maintains the best way to determine if the lighting is right is to measure the light with a lux meter The LX 1 uses a silicon blue sensitive photodiode that provides a measuring range of approximately 10 to 50 000 lux The meter range can be adjusted at three levels 10 100 and x 1000 with the unit s LCD indicating which measuring level to use There s also a HOLD button to freeze the meter reading power is supplied by a single 9 volt battery Price 190 95 CIRCLE 57 ON FREE INFORMATION CARD Automatic Fruit and Vegetable Peeler We ve never really been sure what the culinary term julienne means but Hammacher Schlemmer 147 57th S1 New York NY 10022 says this Automat ic Fruit and Vegetable Peeler will do it Julienne that is along with automat ic
4. box certainly won t do especially as applied to the elegant new Hi Fi To Go Audio Unit PHD815 from the Fisher division of Sanyo Fisher USA Corp 1200 W Artesia Blvd Compton CA 90220 The company says the product emphasizes convenience features and upscale design includ ing sculpted speaker enclosures detachable two way speaker system CD output jacks and AC DC operation The PHD8IS s dual cassette system includes a sequential play function which allows playback of two cassettes in uninter rupted succession and auto reverse playback in the unit s A deck There s also an AM FM stereo quartz synthesized tuner with station presets and an autoscan function A five band graphic equalizer and Dolby Noise Reduction round out the upscale package Price 439 95 CIRCLE 55 ON FREE INFORMATION CARD Dial It Cordless Tone Generator For those telephonic diehards who refuse to get with it and go completely electronic or forthose who through no fault of their own find themselves stuck at a rotary or non tone dial phone Dictograph Corp 37625 Walden Ave Lan caster NY 14066 has the Dial It Cordless Tone Generator 100 Quartz crystal controlled the device provides access to beeperless answering machines comput ers pagers and dictation systems Besides a standard telephone keypad the Dial It has as Dictograph puts it four special buttons for access to new services provided by phone companies and comput
5. BLS1K 100 000 WATT BLASTER DEFENSE DEVICE ITM1K 100 000 VOLT 20 AFFECTIVE RANGE INTIMIDATOR PSP4K TIME VARIANT SHOCK WAVE PISTOL PTGIK SPECTACULAR PLASMA TORNADO GENERATOR 149 50 e MVPIK SEE IN DARK KIT lir ASSEMBLED e PTWIK SPECIAL EFFECT VISUAL PLASMA GENERATOR FOR GLOBES NEON TUBING ETC i e BTC10 50 000 VOLT WORLD S SMALLEST TESLA COIL ig 5i e LGU40 1MW HeNe VISIBLE RED LASER GUN 952 e TAT30 AUTO TELEPHONE RECORDING DEVICE 4 e GPVIO SEE IN TOTAL DARKNESS IR VIEWER 349 e LIST10 SNOOPER PHONE INFINITY TRANSMITTER 169 5j IPG70 INVISIBLE PAIN FIELD GENERATOR MULTI MODE 74 50 e CATALOG CONTAINING DESCRIPTIONS OF ABOVE PLUS HUNDREDS MORE AVAILABLE FOR 1 00 OR USE OUR PHONE FOR ORDERS ONLY 603 673 4730 PLEASE INCLUDE 3 00 PH ON ALL KITS AND PRODUCTS Aig POSTAGE PAID SEND CHECK MO VISA MC IN US FUN INFORMATION UNLIMITED P 0 BOX 716 DEPT HO AMHERST NH 03031 G pattern nx NO CAMERA NO FILM NO DEVELOPER with complete instructions Works with all common etchants DE 973 Master Assortment 69 pattern sheets Add 2 00 shipping NJ and residents also add sales tax DATAK Corp 3117 Paterson Plank Rd Bergen NJ 07047 34 95 CIRCLE 17 ON FREE INFORMATION CARD 886 H38OLOO 02 HANDS ON ELECTRONICS Electronics Paperback Bo
6. 104 Radio Electronics back issues 1984 5 25 December 1984 issue is not available Write in issues desired h 1 103 Radio Electronics back issues 1983 5 50 Jan Feb May are not available Write in issues desired 102 Radio Electronics back issues 1982 5 75 Jan Feb is not available Write in issues desired 193 Etch your own PC boards 154 How to Repair VCR s 155 Typewriter to Computer 125 Radio Electronics Annual 1985 126 Radio Electronics Annual 1986 156 How to Make PC Boards 157 All About Kits 158 Electro Importing Co Catalog 1918 159 Low Frequency Receiving Techniques Building and using VLF Antennas 160 New Ideas 42 Circuits 161 Descrambling Feb 1984 162 Build Your Own Satellite TV Receiver 7 00 163 Receiving Satellite TV 11164 Modern Electrics April 1908 2 2 165 How to Repair CD Disc 5 00 166 Collected Works of Mohammed Ullyses Fips 62 pages April Fools Collection 1167 Designing With 5 Et CEJTSEJESETEJES EC 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 506 per page Indicate the issue month amp year pages and article desired Include payment in full plus shipping and handl
7. YOUR BUDGET WAS UP AGAINST THE wall when you got your IBM compatible computer it s an odds on bet that you opted for the color graphics card with a composite monochrome monitor because the combination is relatively inexpensive yet it allows you to run software intended either for the monochrome card with TTL monochrome monitor or for the color card with RGB red green blue color monitor Either way you saved several hundred dollars Unfortunately the composite monitor IS connected to the color graphics card and winds up receiving color information which creates garbage on the screen of a composite monitor In fact of the 16 pos sible IBM type colors twelve create cross hatch pattern on a composite monitor while the remaining four colors merge into the shadow and highlight de tail Although it is possible to get a clean screen display from a color program on a composite monochrome monitor it can only be done if the software specifically disables the color mode As a general rule a composite monitor can be used with most of the popular soft ware intended for either monochrome or RGB systems such as WordStar for word processing mono or The Print Shop for signs color can be automatically disabled by the program but if a color program makes no provision for disabling the color information the display poops out as shown above Shown is a composite photograph of screen displays The left side
8. 48784 OCTOBER h 1988 4 THE MAGAZINE FOR THE ELECTRONICS ACTIVIST A modern version of that fascinating device Tower speakers that deliver top notch sound and you can build them yourself Pointing devices make life with your PC more fun Improve the performance of AM radio Is the problem in the motor or elsewhere After reading this article you ll know Computer Speech Synthesizer Give your computer the gift of gab T gs LE 8 AK Puerto Rico 218 681 8674 Yoien 82827914 INTEGRATED CIRCUITS lt b 1 METAL ORIDE FILMA RESISTORS im 1 4 Wor 7400 TTL 74500 TTL Pert Pan Pom WM Metal fam Aseortments ABE n921 22 ABIX 129 9 WIREWOUNO REC RESISTORS Avetghis ntk 00 wen Won Mee Regator Aanoctrmervte x XY 57065 8 Sere 3 tam inti Appro rene te o waves 0 47910 Rts 1 Wor egantos m TRANSFORMERS Ouai Becandery angie Prwnars 1190971 0 end VA Wart Srenetermnen 1 Xi 1 AMP SILICON RECTIFI 5 CARBON FILM RESISTORS Avqiatpio ih 1 8 1 4 p 1 7 Want Wart Reastor Aseortments Wart fiessstos amp tbortements 2 Wer Aawer Assortments Deg Rey wide daigun and yee gte
9. BP110 HOW TO GET YOUR ELECTRONIC PROJECTS WORKING 5 75 simple projects that you can use with your Car or boat All are designed to operate How to find and solve the common problems that can occur when building projects from 12 volt DC supplies Ll ELECTRONICS BUILD AND Etecteomc Corcusts ler tha SHIPPING CHARGES IN ELECTRONIC TECHNOLOGY TODAY INC USA AND CANADA Box 240 Massapequa Park NY 11762 0240 T SHUT zm ee L 0110 5 00 1 5 01 to 10 00 2 00 Na Total price of merehandise i pode e Sales Tax New York State Residents only Address 30 01 is 40 00 55 00 Shipping see City State Zip 40 01 to 50 00 6 00 All payments must Total Enclosed H10 88 550 01 and above 7 50 be in U S funds WATCH mus ISSUE FEATURING BUILD THE BREATH ALERT This electronic alcohol checker can save your life ALL ABOUT ISDN How the Integrated Systems Digital Network will change the way you use your telephone REACTS How to add X 10 compatibility to the Radio Electronics Advanced Control System BUILD A DIGITAL TELEPHONE LOCK Prevent unauthorized telephone calls from being made on your line EMBER 1 1989 HARDWARE HACKER SHORTWAVE RADIO Don Lancaster looks at
10. arako IF YOU HAVEN T SEEN THE FREE MARK V ELECTRONICS CATALOG HURRY UP YOU LE FIND EVERYTHING SUITABLE AND ESSENTIAL FOR FACTORIES SCHOOLS PROFESSIONALS AND ENTHUSIASTIC AMATEURS OVER 60 S OF ASSEMBLES AND KITS WITH DIFFERENT LEVEL OF DIFFICULTY FOR KIT ASSEMBLY BEGINNERS 6WX2 STEREO MINI AMP LIGHT CONT ROLLER BATTERY FLUORESCENT LIGHT DRIVER AND MORE INTERMEDIATE 44D P M 0 50V 3A POWER SUPPLY 120 MOSFET POWER AND MORE PROFESSIONALS 1 2GHZ FREQ COUNTER 300W 4680W 4 CHANNEL PRO COLOR LIGHT CONTROLLER AND MORE ANYWAY THE SELECTION 15 INCREDIBLE THE VALUES ARE EVEN SETTER AFTER ALL ASK FOR YOUR OWN COPY TODAY YOU LL HAVE MORE THAN CATALOG MORE THAN A REFERENCE YES PLS SEND ME A COPY OF THE ALL NEW FREE MARK V CATALOG NAME AOORESS CITY STATE MARK V ELECTRONICS INC 8019 SLAUSON AVE MONTEBELLO CA 90640 FAX 213 888 1029 OFFICE HOURS IPACIFIE TIME ooo Ro INFORMATION 213 888 8988 CIRCLE 16 ON FREE INFORMATION CARD 8861 HAGOLIDO ww HANDS ON ELECTRONICS NEW PRODUCTS On the TR RW490 both transports can record allowing the user to make simultaneous recordings of the same source Sequential recording to one cassette after the other increases record ing time to three hours when two 90 minute cassettes are used The Mode TA RW470 uses a real time tape counter for the record play back transport providing accurate elap sed
11. hb apply Mert ers koy tency Lee for 4 mE uem thal ore cul decpount liie ane identified by the sults ND loliowing the pari number After nt order total of rhe discountatiie items and apply the appropriate decount To the subtotal add the fjrcountabie tems Then add the s furge We pay s wpping end insurance to adresses in the U S Canada and Meaico when check or money ode a comppres order Duy Key vhs orders witten the 3E Y Hawan Canada end Meuco WHEN OADERING BY PHONE CALA 1 900 344 4535 AM coli 210601 6674 BY MAIL SEND YOUR ORDER TO REY PO Bon 627 Thiesi River Polis MN 56701 You may by chech money order Master VISA of COD GUARANTEE Any pots pul haved frum Day Key the prow to he defective ati be ET oxi returne anthun 90 days bror with 8 copy 0f ynu gt PRICES SUBJECT TO CHANG WITHOUT NOTICE CIRCLE 11 ON FREE INFORMATION CARD 0 344 4539 9103508982 DIGI KEY CORP DISC CAPACITORS PEL i 5388 8 REBSRES EI BY 2 888 TEE 5 E PANAGONAC SERVICE CHARGES 8 00 1946 6250 4 28 00 08 00 TT 9T 700 88 amp Up Add 62 08 0 35 Charge 22x 57 00 2 o0 47 4 00 00
12. Box 2824 San Francisco 94126 Please rush FREE details immediately 1 0 NAME _ 1 ADDRESS l aua k 8861 1 HANDS ON ELECTRONICS FOR SALE TRANSISTORS tubes MRF421 24 00 MRF454 14 50 MRF455 MRF 477 11 75 MRF492 16 00 SRF2072 12 75 SRF3800 17 50 25 2290 16 75 25 2879 22 00 6LF6 6LO6 6JS6 8950 etc call New RANGER AR3500 all mode 10 meter transceiver 319 Quantity discounts Best prices on hard to find parts antennas miCs power supplies amp equipment Catalog 1 00 refundable or free with order RFPC Box 700 San Marcos CA 92069 For information or same day shipment call 619 744 0728 Visa MC C O D THE invention of television Fascinating story of how radio motion pictures and television were in vented 144 pa es 45 rare photos Send 10 00 ck MO BELLTOWNE PUBLISHING 10011 Belltowne Sugarland TX 77478 TUBES 59 Year guarantee Free catalog Tube tester 8 95 CORNELL 4219 University San Diego CA 92105 CABLE TV equipment 5 Jerrold Zenith Hamlin Oak Eagle filters remotes and more Best prices C O D s acc dealers needed Ours work where others failed and we guarantee it TRANS WORLD CABLE CO 1 800 442 9333 CABLE TV decoders Jerrold Scientific Atlanta Zenith most major brands dealer inquiries wel come Visa M C accepted
13. NOS STE Ie he tries to offer flower Road Levittown PA 19067 M n sn nn US made Collins transmitters 1020 kHz medium wave and on the 6 025 kHz shortwave frequencies In addi tion the station operates on 94 MHz FM Obviously only the 6 025 kHz shortwave frequency is possible in North America and even that isn t the easiest log Still it can be heard by patient careful SWLs in Spanish or in a local Indian dialect during the early morning hours before the 49 meter band gets too crowded say around 0900 to 1000 UTC Feedback Dean Thompson of Belding has a question about buying a shortwave receiver 1 know nothing about elec tronics and am very new to DXing he writes like to shop for a better receiver in my price range Is there a Consumer Reports type of listing of SW receivers Your column is a big help to a beginner like me but so much of the information I ve found elsewhere is over my head OK Dean but first a quick editorial comment When one is just getting started in shortwave listening there are questions seemingly dozens of ques tions All of them are important None of them are dumb One common misconception is that it takes vast technical knowledge to be a DX listener True there are many who are in fact very much into the elec tronics end of the hobby But there also are many SWLs who are not at all tech nicall
14. Jo op 5 PANASONIC V SERIES Samed betoni F Ro PANASONIC 8 SERIES Paty on tes Cane enema g OPTOELE TROMICS Less 10 Lese 16 Less 20 Less 25 pce GIZMO Volume 5 No 10 1988 CONSTRUCTION Computer Speech Synthesizer give your computer the gift of gab Solid State Tesla Coil build this solid state version of most famous experiment BC Antenna Coupler liock in those distant stations with an external antenna Towers of the speakers you want without havng to second guess the manufacturer Magnetic Jumping Beans your friends and family will get a kick out of watching these little fellows do their tricks 30 FEATURES The Gravity of Things gravity may not be the constant that everyone thinks it is Of Mice and More look at whats available in pointing devices Identifying Defective Motors pull those old tape decks and turntables out of the closet and put them back on track E Z Math Network Analysis learn the right way to analyze electronic circuits HANDS ON REPORTS Avocado Computer a Aa composite monochrome with 16 brightness levels from your CGA card Digital Voice Recorder an adaptable modular kit puts computer age gadgetry on your workbench SPECIAL COLUMNS Ellis on Antique Radio a littie housek
15. fahnestock clips are mounted to the board on inch alumi num spacers using 6 32 hardware A 1 inch length of 12 solid copper wire is fitted in one end of a 1 piece of dowel rod to produce the adjustable terminal of the spark gap The other gap wire must be made from a 26 or smaller wire for the gap to perform properly Place the four dowel rods in the baseboard position the 9 inch deck on top and press down until all four dowel rods are even with the top of the circle Connect the bottom of LI using a short length of 12 wire to the main grounding point see Fig 3 Also connect the bottom end of L2 to the same point A separate vertical ground rod can be positioned on the deck see photos for additional experimenting The vertical ground was made from a 29 inch length of 4 inch threaded rod and covered with a section of aluminum tubing to give a neat appearance At the top a binding post was mounted for REPRINT BOOKSTORE SP1 Special Projects 1 Winter 1980 SP4 Special Projects 44 Summer 1982 P5 Special Projects 5 Winter 1983 P6 Special Projects 6 Spring 1983 P7 Special Projects 47 Summer 1983 P8 Special Projects 8 Fall 1983 P9 Special Projects 9 Winter 1984 P10 Special Projects 410 Spring 1984 11 Hands On Electronics 1 12 Hands On Electronics 2 13 Hands On Electronics 43 14 Hands On Electro
16. 5 00 Inciudes a Shde Timer Signal Gen Mike Pre amp Scratch Filter and much more BP185 ELEC TRONIC SYNTHESISER CONSTRUCTION 5 95 Shows how to a monophon syn thesizer section by section Repiaces 81 State _ 8P148 COMPUTER TECHNOLOGY PLAINED 5 50 Explanations tor comput er terms often encountered A dictionary fot computer ingo BP110 HOW TO GET YOUR ELEC TRONIC PROJECTS WORKING 5 75 How Io find the fauits In your prosecis repair them and get them working more belore they Duy 8 x 10 in wansmutiers KDKAS beginnings and much more of audio Ssignais Pnncipies and practices of digilal audio lechniques 7 BP105 ANTENNA PROJECTS 5 50 Practical antenna designs that deliver good performance and are rel atively smpe and inexpensive to bud BP152 INTRO TO 2 80 MACHINE CODE gt 5 95 up your programs They may be harder Io wre but 115 worth learning how Sorne derno programs are included Quality Paperbacks THEORY 6 95 antennas ob Electron d we f 8P121 OESIGN amp MAKE YOUR OWN PC BOARDS 5 75 Ev erything you need 1o know before you make printed circuit boards tor your proyects _ BP85 INTERNA TIONAL TRANSISTOR EQUIVALENTS 7 50 Locates possibile subsitiules for a popular user onented selectio
17. 5 volt and monitor Jacks all are black were positioned in the lower right Mount R4 in the 2 inch hole above the 0 5 volt and monitor jack terminals The two monitor banana jacks are provided so that the variable voltage can be monitored with a VOM or DMM without fuss Wiring it Up Solder two 6 inch long hookup leads to the AC neon light indicator and tie them to the primary leads of the transformer and the AC line cord Tape up each set of leads separately Tuck the taped leads near the base of the transformer Next connect and solder all the leads from R4 to SI and their associated jacks Tie the monitor jacks wiring to the variable 0 5 volt DC jacks All wires to 51 should be tinned so they can be easily connected to the screw terminals Check each voltage wire and solder them to their respective voltage terminals If available use a black hookup wire for the ground or common jack If only one color of hookup wire is used tie a knot in the ground wire for easy identification Recheck each mounting wire from the board to the correct part on the front panel Testing the Box After double checking all voltage connections and tie wires the Motor Voltage Box is ready to be tested Plug in the AC cord the neon pilot light should light up at once If not check for the correct voltage at each IC input and output Take voltage measurements at all of the fixed voltage out puts Feel each IC and heat sink to see if they are very
18. BASIC BOOK 6 95 book on the BASIC for those who have nol yel bought a compuler 5 well as those who have trouble learning how to program BP239 GETTING THE MOST FROM YOUR MUTLIMETER 5 95 Covers basics of analog and digital meters Methods of component testing includes transistors thyristors resistors Capacitors and other actrve and passive devices Rasy Adon Circuste Jor ihe Amerie Dara Compute Ee ots A 4 Ceoniretat VIC asc Mave Robets B hears a al BP144 FURTHER BP ELEC PRACTICAL ELECTRONICS CALCULATIONS AND FORMULAE 9 00 Companion voiume to BP53 Book carners on with new dala nol found earher edition 450 pages 1 8P125 25 SIMPLE AMATEUR BAND AN 5 50 All kinds ol antennas lor all kinds of amateur radio reception 2 BP117 PRACTICAL ELECTRONIC BUILD ING BLOCKS Book 1 5 75 Build the biocks and then combine them to form any custom project of your choice BP77 MICRO PROCESSING SYSTEMS AND CIR CUITS 5 95 Guide lo the elements of macro gor Systems al the tunga Teaches BP97 IC PROJ ECTS FGR BEGINNERS a 5 50 Witten es pecially for the less experienced experi menter Complete parts layouts and wiring di agrams 161 THE QL ARCHIVE 4 95 Presents the powertul database
19. Included with the DAS 8PGA are MetraByte s utility software package and a users manual The utility software pro vides a complete assembly driver and installation calibration example programs A few simple operational data acquisistion programs are also included The assembly driver is compatible with both compiled and interpreted BASIC It performs all the actual board I O commands The DAS 8PGA costs 560 00 For more information contact MetraByte Corporation 440 Myles Standish Blvd Taunton MA 02780 Tel 617 880 3000 Quad Section Mesh Antennas The CFA T Lock Plus Model 1131 and Model 1 132 quad section mesh anten nas are designed for quick assembly and dependable operation under a wide range of weather conditions The Model 1131 has buttonhook feed support and the Model 1132 has quad pod feed support Twenty extruded T Lock support ribs made of T 5 aircraft aluminum effectively maintain precise parabolic curve for a F D ratio of 0 4 Each an tenna panel made of precision ex panded and rolled aluminum mesh is preformed to the proper parabolic CIRCLE 30 ON FREE INFORMATION CARD curve prior to installation on handles The resulting surface is smooth and accurate delivering a Ku band gain fig ure of 47 25 dB The CFA T Lock Plus antennas have a suggested retail price range of 400 00 to 465 00 and are available from eral Instrument Corporation VIDEOCI Division 6262
20. PIN 7 RESISTOR 14 PIN 13RESISTOR WHY THOUSANDS CHOOSE JDR QUALITY MERCHANDISE COMPETITIVE PRICES MOST ORDERS SHIPPED IN 24 HOURS FRIENDLY KNOWLEDGEABLE STAFF 30 DAY MONEY BACK GUARANTEE TOLL FREE TECHNICAL SUPPORT EXCELLENT CUSTOMER SERVICE CALL FOR VOLUME QUOTES EXTENDER CARDS BYPASS CAPACITORS m ROS 01 1 CERAMIC DISC 100 55 00 01 4 MONOLITHIC 100 10 00 1 CERAMIC DISC 100 56 50 1 A MONOLITHIC 100 12 50 SHORTING BLOCKS 5 1 00 PROTOTYPE DEBUG TING Pi amp SMe 19 8088 FORXTSYSTEM 29 95 80286 SYSTEM 39 95 PEE EE EXT 16 MICROCHANNEL 16 BIT 69 95 GNAPABLE EXT 32 MICROCHANNEL 32 BIT 99 95 HEADERS BE 5 APART TO MAKE ANY SIZE HEADER ALL WITH 1 CENTERS 1440 STRAIGHT LEAD 1240 RIGHT ANGLE LEAD 49 2 40 2 STRAIGHT LEADS 2 49 2x40 2 RIGHT ANGLE LEADS 2 99 ai VU TE acd I SOLDERLESS BREAOBOAROS WBU D 100 TIE PTS 2 95 WBU 204 WBU T 630 TIE PTS 6 95 WBU 206 WBU 204 3 1360 TIE PTS 17 95 WBU 208 mm 99 1660 TIE PTS 2390 TIE PTS 3220 TIE PTS 39 95 SPECTRONICS CORPORATION EPROM ERASERS 3 VOLT LITHIUM BATTERY 1 95 HOLGER 1 49 CONNECTORS RIBBON CABLE CONTACTS 10 20 26 34 IDHzzS 82 129 IDHxxSR 85 31 35 IDH xxW 298 IDH xxWR 5 328 IDSxx 89 IDM xx 5 50 IDE xx 1 25 135 175 205 245 RCxx 3 20 4 10 5 40 16 40 17 50 NNI Ww DESCRIPTION ORDER BY 40 50 68 220 2 58 3 24
21. has a computer program to quiz the student the information presented Other programs provide practice and experience with ohmmeters voltmeters ammeters and oscilloscopes Learning Electronics Theory and Experi ments explains the fundamentals of elec tronics including the math necessary to sup port each concept Some of the topics cov ered are meters DC and AC circuits sol dering techniques basic hand tools and engineering notation Projects and experiments illustrate the prin ciples that are presented throughout the text and practice exercises in mathematics are included Sample exams and answers are also provided Computer programs which graphically illustrate the electronic concepts and mathematical relationships are supplied Learning Electronics Theory and Experi ments costs 16 95 and is available from Tab Books Blue Ridge Summit 17294 0850 Tel 1 800 233 1128 CIRCLE 98 ON FREE INFORMATION CARD CRASH COURSE IN ELECTRONICS TECHNOLOGY By Louis E Frenzel Jr If this book seems familiar at first glance thaf s because its author Louis E Frenzel Jr has been writing learning courses for Hands on Electronics for years Like his articles Crash Course in Electronics Tech nology is a tutorial with a step by step for mat It will help hobbyists students and lay persons learn the basics of electricity and electronics Crash Course in Electronics Technology is a complete self s
22. 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 want to get started Send me my CIE school catalog including details about the Associate Degree Program I am most interested in computer repair television high fidelity service telecommunications LJ medical electronics robotics automation C broadcast engineering Ci other Address State ___ Area No Check box for G I Bulletin on Educational Benefits 7 O Veteran Active Duty MAIL TODAY Print Name CIRCLE 8 FREE INFORMATION CARD 86861 HAGOLOO a ex HANDS ON ELECTRONICS Electronics Library 20 INNOVATIVE ELECTRONICS PROJECTS FOR YOUR HOME by Joseph O Connell Hobbyists might decide to build a project because they can t buy it anywhere because its cheaper to make it themselves or just for the fun of it This 264 page book has projects in each of those categories and some that overlap The emphasis is on unique yet practical devices that are time saving and cost efficient Readers learn how to make a portable mini refrigerator from a cooler a solid state blanket controller active mini speakers with built in amplifiers a flu
23. Fun and Fas Weekend Electronics Project 2861 514 95 i a i tele 7 ET 2925 15 95 E Tr E al PERSONAL COMPUTERS n ANM gi WERTE E MANIS AEREN LETAL TAT m WX LES iS 2809 526 95 2882 24 95 Counts as 2 EN Fite PRONE 101 COMPONENTS SOLDERLESS BREADBOARDING PROJECTS RC BUILDER S BONANZA pa Bln blaah ROSOTK PRI 111 2735P 13 95 2839P 795 values to 131 70 2707 26 95 Counts as 2 Electronics projects ideas the latest technology all at up to 50 off publishers prices Membership Benefits Big Savings In addition to this introductory offer you keep saving substantially with members prices of up to 5096 off the publishers prices 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 tities to choose from Automatic Order If you want the Main Selection do nothing and it will be sent to you automatically 11 you prefer another selection or no book 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 there
24. M 4 Fig 2 Note that only two of the four partitions B require holes The partitions with 2 the holes must be placed inside the cabinet so that the holes will be on the same I side as the front ports See Table 1 for the materials list A A SPEAKER BOARO FACE PLATE GRILL nnas qut It Po O HIODEN e eo RD CC Pa cs pere FRONT BOTTOM ded Fig 3 All dimensions for the cabinet are given in inches The side view A is what you would see with one of the sides removed The front view B is what you would see with the front taken off One brace of each type is numbered and the numbers correspond to those in Table 1 Brace 5 is hidden from both views but is pointed to Special Treatment t s important to add some stiffening and damping material to the walls Asphalt roofing material makes an excellent cabinet liner You can find scraps of roofing at many building sites you only need a few shingles The adhesive called Liquid Nails works well as a glue for the shingles Builders usually recommend an asphalt base adhesive for shingles but they are concerned with perfor mance on the roofs of buildings where weathering occurs The asphalt adhesives seem to take weeks to set so Liquid Nails is strongly recommended Apply a coating of the adhesive on the enclosure wall then quickly staple a piece of shingle over it Do that for all the inner surfaces of the larger chamber exce
25. Not Public Enemies n Saxon on Scanners Hands on Electronics August 1988 it says that according to one state s laws 7 no body except licensed hams can have mobile receiver that is capable of receiv ing frequencies used by police agen RADIO JOUTLET Ge a Pe pt at la o s a es ap 2 I could have sworn this turkey stole radio on his wav out HOLD IT ANYW anaVise electronig in without remos ing from their holding devices X ith 50 years experience and T quality PanaVise ensure reliable long lasting service Self Centering Head opens to Standard Base moves and convenient Tray B parts wells items with ease HERE YOU WANT IT work holding systems OSE WORK CENTER pes ctr Extra Wide Opening 9 famous split ball in three planes ase Mount with handle difficult to hold Model 350 52 95 CIRCLE 7 ON FREE INFORMATION CARD cies yet that state doesn t explain why hams would have any more reason to monitor police transmissions than any one else As a ham offer some en lightenment to anyone who may be won dering about that While most law enforcement agen cies now use the UHF bands tor their routine communications some local and regional public service agencies continue to plug along in the VHF spectrum
26. Practicality aside the Visitel is a fun toy to play with n terms of sophisticated tele communications however we came away thinking of a childhood toy called a Viewmaster That device which inci dently is still being manufactured is an update of the I9th century stereopticon In some ways the stereopticon and the View master viewer were the primitive forerun ners of the contemporary explosion in image related entertainment equipment Perhaps in the same way in future years the picturephone and the Visitel will be seen as a first step leading to a new era of private audio visual communication Changes are in store for the Visitel At the summer CES the company indicated that the new model LU 501 is equipped with video outputs allowing Visitel trans mitted images to be stored on videotape One modification we would suggest is a remote control wired or otherwise for the send function Between holding the tele phone receiver and sitting at the optimum focusing distance a user often ends up sending a shot of his or her arm reaching for the transmission button One odd aspect of using the Visitel is watching yourself on the screen between transmissions of still pictures It s face to face situation alright but then so is sit ung in front of a mirror while making a call Both Panasonic and Sony have de veloped similar devices that thankfully can communicate with each other The Visitel and competing p
27. The microphone has three terminals two of which the negative terminal and the metal tab are connected together by one lead and connected to terminal MIC The other microphone terminal connects to terminal pin MIC fuse holder S1 S3 SPST pushbutton switch 54 56 5 5 toggle or slide switch optional SPKR1 Speaker 2 to 5 in diame ter 4 ohms or higher Plastic or aluminum cabinet wire etc A complete set of parts that mount on the printed circuit board the printed circuit board condenser microphone MIC1 and light emit ting diode LD1 can be purchased as the Digital Voice Record Play back Module Kit K2653 from Tapto Corporation for 61 95 which in cludes postage and handling CO residents must add appropriate sales tax Send order to Tapto Cor poration P O Box 44247 Denver CO 80201 or call 1 800 873 8001 to order only For a catalog of kits and other inter esting products you can write to Tapto at the address above or cir cle No 82 on the Free Information Card in this issue power supply should have an on off switch and be rated at 300 milliam peres or better For safety sake provide a 0 5 ampere fuse the positive volt age lead between the power supply and the printed circuit board Turn the three potentiometers to their mid point position and turn on the sup ply Watch the project carefully for signs of trouble such as smoke or over heating components if any turn
28. entire 12 volts generated by the battery All we are getting is 10 volts across the load Where is the other 2 volts The answer is it is being dropped across the battery s internal resistance Looking at Fig 2B you can see that as current flows through the internal resistance it produces a voltage drop of volt 2 amperes 2 volts The polarity of that voltage drop is as shown in the figure The polarity is opposite to that of the battery polarity and so the two voltages oppose one another That s why we say that the 2 volts across the internal resistance takes away from the battery voltage leaving only 10 volts across terminals and B which are the actual battery terminals That is why you see only 10 volts across the load All that makes sense because Kirchhoff s law tells us that the sum of the voltage drops is Vu V 2 10 12 volts Now you can see why an ideal voltage source is so desir able With zero internal resistance all of the voltage gener ated is applied across the load Since perfect voltage sources can t be obtained in practice then the objective is simply to keep the internal resistance as low as possible That is always the basic design objective of most engineers The lower the internal resistance compared to the load resistance the great er the amount of voltage that appears across the load One way to analyze a voltage source with its load is to look at the internal resistance and the
29. or a dry rail or gear assembly when the rotation is slow Do not apply external voltage to a small motor with more than three terminals Phono Motor Tests Most of the motors found in phonographs operate from the power line except for small battery powered record players Check the continuity with the low ohm range of your ohm meter Measure the AC voltage across the motor terminals with the player turned on If the line voltage is found at the motor connections with normal continuity suspect a gum med up motor or open windings Spin the motor pulley with your fingers If the motor starts to rotate after giving it a spin remove and wash out the bearing with cleaning fluid Sometimes if the phonograph is left on for extended periods of time the motor bearings may get hot and freeze up A slow phono motor may result from gummed up bearings while noisy rotation indicates a dry bearing A couple of drops of light oil may clear up a slow and squeaky bearing Finding where motor related problems lie is a snap once you know how Now that you ve read this article you do OST OF THE MATHEMATICAL OPERATIONS USED IN electronics are perlormed for one of two purposes First the math helps to analyze a circuit In analyz ing a circuit you find out not only how it works but what the various current voltage and impedance levels are Circuit analysis allows you to experiment with the circuit mathe matically to determine how conditions
30. the 150 MHz through the 1 70 MHz bands One of the most heavily populated ham bands the 2 meter band resides just below those VHF public service frequen cies at 144 MHz to 148 MHz Recognizing the broader appeal of expanded frequency coverage many amateur radio manufacturers now selling 2 meter mobile transceivers that receive from approximately 138 MHz to 175 MHz Transmission of course iS restricted to the 2 meter band as re quired by FCC regulations With the no police scanners in vehi cles laws the installation of an ex panded trequency 2 meter transceiver in vehicle became potentially a de facto crime However the mish mash allow vou to position and rotate STANDARD PANAVISE Our most popular vise the Standard Pana is an extremely versatile usefu 1 full tool Jaws open i pe ball 225 and the patented base tilts turns and rotates m three planes One convenient knob locks work into position This durable all purpose a stands about 6 tall and will um liver years of rugged service Mode 301 33 95 of conflicting laws and ordinances are mostly unenforceable to the benefit of hams and the community in general in my area at least The Amateur Radio Emergency Serv ice ARES group in Santa Barbara works in close harmony with numerous local regional state and national emer gency and diSaster service
31. under it Mounting screws are unnecessary Glue a ring of Continued on page 106 61 OCTOBER 1988 Visitel Visual Telephone Display pg 1 Walkman Stereo Cassette Recorder meee CH 6 amp TES Swisstel Telephone pg Sony 8 mm Video Camcorder Dial It Cordless Tone Generator 2 iustus eee Fisher Hi Fi To Automatic Peeler Electronic Auto Compass Nikko Gamma Tuner Packtronics Video Light Meter Plus U S A Uovo Nuovo Case Logic 120 Cassette Case Citizen Portable Fax Machine Desk Top Office Revenger Fascinations Movie Viewer o Swimtech Lap Counter Citizen Hand Held LCD TV pg 10 Code A Phone Tapeless Answering OUTED Onkyo Universal Remote pg 10 Panasonic Scientific Calculator pg 10 Ricoh Personal Portable Copier pg 10 Aiwa AM FM Stereo Recorder pg 11 Braun Food Processor pg 11 Panasonic Clock Radio pg 11 Sharp Microwave Oven pg 11 Telephone Message Stopper Bose Roommate 1 Powered Loudspeaker Hitachi Four Head VCR Serpico Recreational Vehicle gt 2 9 9 9 FF E gt Sharp High Speed Facsimile Workstation Anti Glare Filters GIZMOLOGY TODAY CIRCLE 50 Show Tell VISITEL
32. 0 47 100 WVDC mylar C4 0 33 uF 100 WVDC mylar C5 1500 pF 10K WVDC three parallel connected 500 pF doorknob capacitors see text ADDITIONAL PARTS AND MATERIALS F1 1 ampere fuse L1 L2 see text 51 5 5 miniature toggle switch T1 117 volt primary 18 volt 2 ampere secondary Stepdown transformer T2 Automobile ignition coil Ford 6525 or similar Perfboard 12 wire 426 wire aluminum Fahnestock clips spacers solder hardware etc FEATURES Wide supply voltage range 3 0V to 15V 8 High noise immunity 0 45 Vop typ Low power TTL fan out of 2 compatibility driving 74L Low quiescent power dissipation 0 025 un W package 9 5 0 INH Single supply Operation Input Impedance 1072 N typicall Plug in replacement for MC14514 14515 ABSOLUTE MAXIMUM RATINGS Voo DC Supply Voltage 0 5V to 18V Vin Input Voltage 0 5 to Voo 0 5V Ts Storage Temperature Range 65 C to 150 C Package Dissipation 500 mW m T Lead Temperature Soldering 10 seconds 260 C I3 4 15 16 17 18 18 RECOMMENDED OPERATING CONDITION Voo DC Supply voltage 0 to Voo Vin Input vonage 0 to Voo T4 Operating Temperature Range CD4514BM CD4515BM 55 to 125 C CD4514BC CD4515BC 40 C to 85 C Introducing Electronics FactCaras Each issue Hands On Electronics will present 3 new FactCards each ing with one of a variety of electronics top
33. 00 5 01 to 10 00 2 00 40 01 to 50 00 6 00 10 01 to 20 00 3 00 50 01 and above 7 50 20 01 to 30 00 4 00 SORRY No orders accepted outside of USA and Canada Total price of merchandise Shipping see chart Subtotal Sales Tax NYS Total Enclosed Name Address City State 1 Zip likely to need in his day to DIGITAL VOICE RECORD PLAYBACK PROJECT Continued from page 65 Then if for some reason longer mes sages are required they can be accom modated by closing the switch The sensitivity of the condenser mi crophone can be adjusted with the REC VOLUME potentiometer RV2 Adjust RV2 so that the maximum input signal is available just prior to overloading the circuit There s no meter or other in dicator for that so you ll have to use your ears as a VU meter for that The VOLUME potentiometer RV3 as its name indicates controls the output sig nal to the loudspeaker If you connect the TWICE connector pin to the terminal the message that is stored within the module is played twice each time the PLAY pushbutton switch is depressed The stop switch S3 can be used to terminate recording or playback Some Ideas Now you have the built a basic Digi tal Voice Record Playback M
34. 110 KNOWLES DRIVE LOS GATOS 95030 LOCAL 408 866 6200 FAX 408 378 8927 TELEX 171 110 OIP PLUGS IDC RETAIL STORE 1256 SOUTH BASCOM ANE SAN JOSE CA 408 947 6881 HOURS 10 7 SAT 9 5 SUN 12 4 S pRDER TOLL F COPYRIGHT 1988 JDR MICRODEVICES CIRCLE 18 ON FREE INFORMATION CARD 8861 H38010DO HANDS ON ELECTRONICS TV RADIO COMMUNICATIONS BP91 INTRO RA DIO DXING 5 50 Ev erything you need to know about radio DXing and how you can get into this fas cinating hobby area An 1 S D 2 BP155 INTL RADIO STATIONS GUIDE 6 95 New edition ists sta tion site Country frequency Fa 7 ERP provides for thou A J sands of short wave radio gt stations Nine sections S cover a variety of broadcast A services O BP105 ANTENNA PROJECTS 5 50 Practical antenna designs including active loop and ferrite types that are simple and inexpensive to build yet perform well Also in cluded are antenna ac cessories 25 himpke Ambur b 5 50 Shows how to build 25 antennas starting with a simple dipole and working on up to beam tri angle and even a mini rho mbic i ii 4 1 BP132 25 SHORT T WAVE BROADCAST AN Jm TENNAS 5 50 Good M antennas can be inexpen Mr EE sive Heres 25 different P ones ranging from
35. 2 E g EXPANDED INPUT BUFFER 12 20 Fig 3 The computer voice synthesizer will accept the output from any RS 232 port and convert it into easily understood speech The RAM buffer allows inputs as large as a full screen of text to be accepted Note that for simplicity the power and ground connections for U6 and U7 are not shown here through some high pass filtering and on to the speaker The Construction 74LS138 U5 and the 74LS04 U6 provide control logic The circuit can be built on a piece of perforated con struction board or on a printed circuit board If you choose to go the printed circuit board route an appropriate pattern is shown in Fig 4 Note that for space reasons it was necessary to show the board at half its actual size A parts placement pattern is shown in Fig 5 Note that unlike many digital projects the printed circuit pattern is single sided That makes the job of transferring the pattern to p Rte 1 the board much simpler Unfortunately it also requires the use of an unusually high number of jumpers 26 in all Make sure all are installed or the project will not work The use of sockets for all of the integrated circuits is strongly recom mended A pin out listing of the card edge connections is The prototype was housed in a home made cabinet made from shown Table l um aluminum sheet metal If you choose not to go to so much After assembling the circuit triple c
36. 20 MHz 799 95 27128 27 256 27256 27512 27 512 8192 8 16384xB 327688 327688 7 80 2 5 MHz 280 CPU 1 25 4 0 MHz Z80A CPU 780 Z80A DART Z80A DMA Z80A P10 280 SIO 0 Z80A SIO 1 Z80A SIO 2 5 0 MHz Z80B CPU 2808 CTC ZBOB PIO Z80B DART 280B SIO 0 Z808 S1O 2 28671 21 0 6500 1 0 MHz 6502 2 25 65Co2 CMOS 7 95 6520 1 65 6522 2 95 6526 13 95 6532 5 95 6545 2 95 6551 2 95 2 0 MHz 6502A 6520A 6522A 6532 6545 6551A 3 0 MHz 6502B V 20 SERIES v20 B 95 20 10 95 4 95 20 10 1295 9 95 8 13 95 9 96 Repiaces 8088 to 12 95 speed PC 10 40 12 95 19 95 19 95 29 95 4 39 4 39 12 95 12 95 6 95 6 95 6 29 DISK CONTROLLERS 1771 1791 1793 1795 1797 2791 2793 2797 8272 765 MB8876 77 1691 2143 9216 5 MHz 8 MH 1 29 1 69 5 95 5 95 1 89 5 95 5 95 5 95 74F 745 74F00 74F02 74F04 74 7aF10 74F 32 74 64 74 74 74 86 74 138 74F139 74F253 74F157 74F240 74500 74502 74804 74508 74510 74532 13 74574 74586 29 745124 49 745138 745153 245157 745158 745163 745175 745195 745240 745241 745244 745280 745287 745288 745299 745373 745374 CRYSTALS 32 768 KHz 95 269 1 0 MHz 2 95 2 95 5 95 11 95 3 95 6 95 2 75 4 25 4 25 6 95 12 95 12 95 9 95 4 45 UARTS AYS 1013 AY3 1015 TR1602 2651 6402 1 6403 INS82
37. 240 CIRCLE 73 ON FREE INFORMATION CARD Sharp Microwave Convection Oven It seems a minuscule step for mankind but the Sharp Electronics Corp Sharp Plaza Mahwah NJ 07430 maintains it s a giant step for a favorite snack food The advance in question is a new popcorn sensor setting added to the firm s Carousel Microwave Convection Oven R 9H80 seems microwave popcorn is the fastest growing segment of the popcorn business and Sharp is responding by adding a special setting to its Deluxe E S P Electronic Sensory Processor microwaves Somehow it seems kind of incongruous to buy a full size microwave oven to prepare small bags of popcorn If microwave popcorn consumption continues growing a microwave corn popper would seem a product destined for introduction Price 599 95 CIRCLE 74 ON FREE INFORMATION CARD Telephone Message Stopper n this the age of the answering machine one of life s little irritations is racing to answer the phone and ending up shouting over the recorded outgoing message as you grapple for the off control The Message Stopper trom Jasco Products Co Inc Box 466 Oklahoma City OK 73101 promises to put an end to the answering machine dash The simple device stops the answering machine when the phone or any extension instrument is answered The answering unit automat ically resets The message stopper also prevents others from overhearing or interrupting a phone call and guards against the i
38. 50 More circuits show to use a variety of co computer add ons in as non technicai a way as possible ing CMOS applications Most are of a fairly simple design C 227 BEGINNERS GUIDE TO BUILDING ELECTRONIC PROJECTS 5 50 How to tackle the practical side of electronics so you Successfully build BP72 A uiris PROCESSOR PRIMER weed We start by designing a small electronic projects computer and show how we can overcome its shortcomings LI 169 TO GET YOUR COMPUTER PROGRAMS RUNNING 5 95 1 BP74 ELECTRONIC MUSIC PROJECTS 5 95 Provides the experimenter Shows how to identity error in program and what to do about them with a variety of practical circuits including a Fuzz Box Sustain Unit Reverberation BP194 MODERN DEVICE PROJECTS 6 25 Crammed with great Unit Tremelo Generator and more projects for the experimenter Includes sections on Fiber optics passive Infra Red detectors plus an assortment of miscellaneous projects 1 BP91 AN INTRODUCTION TO RADIO DXING 5 50 How you can tune on those amateur and commercial broadcasts from around the world in the comfort of BP180 ELECTRONIC CIRCUITS FOR THE COMPUTER CONTROL OF your home MODEL RAILROADS 7 50 It s easy to interface home computers to model allroad trol robi i aci ARRAS Manos Thaman promem iN mterfacing the computer systemi BP94 ELECTRONIC PROJECTS FOR CARS AND BOATS 5 50 Fifteen
39. 98206 Tel 800 443 5853 26 Inch Monitor Receiver Yamaha Electronics Corporation s Model YM 265S video monitor re ceiver has a high resolution 26 inch screen infrared remote control Sepa rate Audio Program SAP Multichan nel Television Sound MTS stereo and Super VHS compatibility 2655 has a high contrast tinted CRT comb filter circuitry a black matrix screen and 560 lines of horizontal resolution resulting in a sharp image S VHS compatibility 1s achieved through a new S connector The unit has antenna inputs for recep tion of all VHF UHF and major cable channels 142 channels tn all and accurate reception is assured by the fre quency synthesized tuner The numeric keys on the remote control provide di rect access to any channel or the up down tuning controls can be pro grammed to scan skipping over unused channels YM 965S s infrared remote control also operates power volume and muting The unit s input source Switching and digital clock and timer display can also be controlled remotely An on screen channel and time display can be Switched on using the remote or from the front panel It can receive standard broadcast TV sound MTS stereo and SAP LED in dicators make sound source selection easy An audio enhancer circuit makes even a mono signal sound impressive Slim speakers built in to the bottom of the unit s front panel and driven by 2 5 watt ampli
40. A review of general conditions and a patents pressure transducers and look at how sunspots affect pressure measurment basics communications 2 VIDEO NEWS COMMUNICATIONS CORNER WHAT S NEWS 3 AUDIO UPDATE DRAWING BOARD ANTIQUE RADIOS HANDS ON ELECTRONICS Ge e SYNT COMPUTER Give your computer the gift of gab with this easy to build fun to use text to speech synthesizer By Jeffery Miles computer talk without programming it Would you like to be able to simply type away at the keyboard hit return and listen to what you had just typed Or how about printing a document to the serial port and listening to it instead of reading it Well the project described in this article will let you do all of that It will take ordinary ASCII code and convert it directly into speech D YOU EVER WISH THAT YOU COULD MAKE YOUR Text to Speech Converter The proiect is built around the SPO256 AL2 speech pro cessor and the CTS256 AL2 text to speech converter chips manufactured by General Instruments The circuit is set up to receive standard ASCII code from virtually any microcom puter or dumb terminal that is equipped with an RS 232 port such as a serial printer or modem port If a microcomputer is used the synthesizer can be activated from a terminal emulator of any communications program or from any pro gramming language such as BASIC Only two of the lines from the RS 232 serial port are connected to the s
41. AS POWER SWITCH GROUNDING ROD Fig 3 The Automatic Switch uses a wire fence as a sensor and a 12 volt relay to control the on off operation of the Audible Critter Chaser Automatic Switch Wouldn t it be great if the sounder circuit could be turned on automatically just when it is needed to drive out an intruder and not have it running all of the time Wouldn t it also be nice if the sounder circuit could be used to protect a specified object or area outside Fear not because the circuit in Fig 3 in conjunction with a fence does just that The fence which is used as a sensor might be a bare wire around a small garden shrub or special tree or even the garbage barrel is connected to the input of the Automatic Switch The re lay contacts can be connected to the Audible Critter Chaser to turn on the sounder each time an intruder is de tected As shown five 22 megohm resistors are connected in series with a 9 volt bias battery ground and the gate of Q3 a 2 4360 JFET fence sensor con nects to the circuit at the junction of R13 and R14 The positive battery voltage fed through the five resistors keeps Q3 biased off 8861 H38OLOO HANDS ON ELECTRONICS tween the gate of Q3 and pene Stick As long as the fence wire is insulated from ground transistor Q3 remains turned off but when something touches the fence while in contact with the Ea
42. Blvd Farmingdale NY 11735 COMPONENTS CATALOG yours FREE by dialing 1 800 992 9943 Today for your FREE subscription to the latest Mouser Electronics Catalog Contains 192 pages featuring over 17 000 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 Mansfield Texas 76063 DISTRIBUTION B 3 CENTERS e COAST TO COAST DEGREE THROUGH HOME STUDY Our New and Highly Etfective Advanced Place ment Program for axperienced Electronic Tech nicians grants credit for previous Schooling and Professional Experience and can greatly 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 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 OF ELECTRONICS ENGINEERING E 4251 CYPRESS DRIVE m JACKSON MISSISSIPPI 39212 CIRCLE 10 ON FREE INFORMATION CARD OOK S INSTITUTE 8861 H38O120 e SOLID STATE TESLA COIL Continued from page 40
43. Chaser Figure 1 shows the schematic di agram of the Audible Critter Chaser The circuit is designed to flood an area RI R2 By Charles D Rakes SPKR1 Fig 1 The Audible Critter Chaser is designed to flood an area with a continuous high frequency tone to frighten away four legged intruders with a continuous high frequency tone to frighten away four legged intruders At the heart of the circuit is a 741 op amp UI that s configured as varia ble pulsewidth high frequency audio PARTS LIST FOR THE AUDIBLE CRITTER CHASER U1 741 general purpose op amp Integrated circuit 01 2N3804 2N2222 or similar general purpose NPN transistor D1 D4 1N914 small signal silicon diode C1 0 0015 uF 100 WVDC mylar capacitor C2 C4 0 1 uLF 100 WVDC mylar capacitor 3 100 16 WVDC electrolytic capacitor F1 R3 R6 1000 ohm Va watt 5 resistor H4 H5 10 000 ohm a watt 5 resistor H7 100 ahm 14 5 resistor 25 000 potentiometer H8 50 000 ohm potentiometer SPKH1 FPiezo tweeter speaker Perfboard material enclosure IC socket 9 to 12 volt power source wire solder hardware etc D oscillator Potentiometer R8 25K sets the frequency of oscillation while R9 SOK sets the pulsewidth of the output signal that s used to drive transistor QI Because the negative output swing of the 741 doesn t go completely to ground and D
44. Done in by video the fall of 8 mm celluloid left a number of manufacturers and suppliers in a potential limbo One of those firms Hama of West Ger many an important supplier of 8 mm ac cessories has continued in 8 mm but changed mediums from film to videotape Among the first results of that reposition ing although the firm remains deeply in volved in the photographic industry is the Video Cut 10 That unit is an editing deck that promises to put sophisticated tech nology within reach of home video enthu siasts or at least those that are well heeled the same consumers who have Pressman Cassette Corder cult to understand how Texas folk singer Michelle Shocked was able to record best selling album of her music using portable Walkman model unspecified In an irony only possible in the current techno overkill atmosphere of the record industry Shocked s Campfire performance from the Texas countryside recorded with a hand held recorder is now commercially available in this Country on compact disc The diminutive WM D3 s versatility is also impressive with excellent playback capability and a plug in condenser micro phone of exceptional quality and small size We used the microphone both clip ped to our clothing and resting on a sup plied stand results in both situations were most satisfactory The unit s impressive dynamic range according to Sony is the result of a laser amorphous tape head
45. Handbook provides a useful col lection of data for the amateur electronics enthusiast so that much of the data he needs is available in a single source The book covers common component color codes and details the characteristics and pinouts of many popular semiconduc tor devices including logic ICs op amps transistors FETs SCRs triacs diodes rec tifiers and regulators Several types of cir cuits are illustrated including timers os cillators audio amplifiers and filters There is a separate section on power supplies Circuit symbols interface details amateur and CB frequency allocations are also pre sented in this 88 page book Some knowledge of electronics is needed to make use of the data which is intended for students designers and technicians as well as hobbyists The Electronic Hobbyists Handbook or der No BP233 is available for 11 95 from Electronics Technology Today P O Box 240 Massapequa NY 11762 CIRCLE 97 ON FREE INFORMATION CARD UNDERSTANDING DATA COMMUNICATIONS SECOND EDITION Edited by Gilbert Held Data communications the process of com municating information using binary signals has become vitalto the American economy and is rapidly gaining importance in homes as well This 291 page book explains how data communications systems and their vari ous hardware and software components work Understanding Data Communications Second Edition covers the basic concepts a
46. IN ORIGINAL BOX Dnw DISPLAY a PAGING RECEIVER Qual Conversion Supere 450 Me HALF HEIGHT EXTERNAL DRIVE An we Low Ca 0 Greet for the Experimenter mn aa AL TED SPECIAL TIE S offers t customen Ungua SUPERMARKE T STYLE shopping ior ANY ALt ELECTRONIC NEEDS We Meraly THOUS ode ed the to sane of the 43t for the electronic enthusiast ea Carry bre of computer eccessonen test eqQupmen toot RAO supplies and much more PLEASE CALL OR ONE OF OUR THRE RETAL STORE S TODAY Ploneer Oisc Pisyer These unts we trom senice for upgrades They run on trom suppied 120 adapte While they shoot be have Meno protiemt vo ee must ser them o an af mm Stace ore Actuated One Bear Spimer Two Optical Lenses All Controling E tems 2 cem 3 CONVENIENT LOCATIONS M i 64 95 Santa Ross Ave 5549 Hemiock Call TUA arem oe k t uu wi ud enters ct 0 CIRCLE 9 ON FREE INFORMATION CARD PC LabCard for AT XT Relay Actuator amp Prototype Devetopmen Card 74 AT XT 3 SLOT MOTHERBOARD EXTENDER m5 JA COMPATIBLE K 90 DAY WARRANTY 3500 RYDER ST SC SANTA CLARA 95051 CA Residents
47. Kirchhoff s laws but they have high sounding names and often intimidate people In real ity they are nothing more than tricks and shortcuts that help you speed up and simplify the analysis and design of circuits In this article we ll cover the popular and widely used Thevenin s theorem iso T A Ve _ 4 4 2 A PO R B bas 4 J Fig 1 These are the simplest ways of representing a current or voltage source They are known as Thevenin equivalents and they greatly simplify circuit analysis 8861 YABOLOO 7 G2 HANDS ON ELECTRONICS 4 A Ohm s and Kirchhoff s Laws Ohm s law is a mathematical statement of the relationship between the current voltage and resistance or impedance in a circuit t states The current is directly proportional to the applied voltage and inversely proportional to the resistance or imped ance In mathematical form Ohm s law is expressed as V R where I is the current in amperes V is the voltage in volts and R is the resistance in ohms For example if a 20 ohm resistor is connected to a 12 volt battery the current is 12 20 6 ampere Using algebra you can rearrange the above formula to calculate the voltage or resistance V IR R V I Kirchhoff s Laws There are two basic Kirchhoft s laws one for series cir cuits the other for parallel circuits Kirc
48. Moon Their clarity of sound with that recording is startling at times If you hear any coloration remove the woofer and rear range the Fibreglas damping material Or add some loose polyester batting behind the woofer When you are satisfied with the sound remove the woofer and solder the connections to it Once again lay the entire unit down Remove the foam weather stripping around the woofer cut out and apply a ring of silicone rubber sealer If you don t want to replace the mounting bolts fill the bolt holes with sealer Set the woofer down twist it a bit for better sealing and leave it until the sealer has set Your towers are now ready to play and play L GRAVITY OF THINGS Continued from page 17 Others have found irregular variations in gravity during experiments conducted in mine shafts but their results re main inconclusive because the density of the rock near the mines is not adequately known which would affect their measurements Since the density of ice is well known our experiment will be much more accurate than any previous geophysical measurements of gravity Basically we are tak ing advantage of the ice as a medium for the instrument to travel through It has a known density unlike the inhom ogeneous rock materials in mine shafts or unlike air which doesn t have a density high enough for the type of measure ments we are making Zumberge said The researchers believe they will be able to measure the g
49. TV monitor sweep and high voltage circuits gener ate harmonic rich signals that interfere with receivers operating in the short wave spectrum Fortunately there are several things that can be done to eliminate the prob lem For one you could use a relatively EMI quiet computer have found that the Commodore fits that description while my IBM PC is unusable around my Kenwood TS 430 transceiver An other way to solve the problem is to use only shielded cables between the com puter and its peripherals Finally you can attempt to shield the computer and filter its supply line Readers with expertise in that area are asked to write to me about their experi ences pass the information on to your fellow enthusiasts Once again we ve run out of space But in the meantime if you have any questions suggestions or comments pertaining to the amateur radio hobby write to Joe Carr KAIPV at PO Box 1099 Falls Church VA 22041 Ej 60HZ TIME BASE DMR 45 4 Digit Ruggedized Multimeter 30 Position Rotary with 5 High Contrast LCD Auto Overrange and Auto Polar ity Diode and Transistor Test ul Buzzer Data Hold and All AC DC Ranges with Resistance 20 AMP Current Range Under 116 00 PS6CL 4 AMP Non Reg with 6 AMP Super Cigarette Lighter Attachment Auto Reset Circuit Breaker Meets All ul specs Under 28 00 Also avil Reg 10 AMP Under 60 00 COSC 10st 5 Single Track Triggered Oscilloscope Up to
50. The Magic Course 500 B BiCounty Boulevard Farmingdale NY 11735 or telephone 516 293 3751 and ask for Nancy Estrada ENGINEERING software tor IBM PC CompDes circuit design CompMath mathematics Com pView waveform viewer 49 each 614 491 0832 BSOFT SOFTWARE 444 Colton Road Columbus OH 43207 WANTED IDEAS inventions new products wanted Call free 1 800 288 IDEA ISC HOE 903 Liberty Pitts burgh PA 15222 CABLE TV CONVERTERS CABLE TV converters Scientific Atlanta Jerrold Oak Zenith Hamlin Many others New Video Hopper The Copy Killer Visa M C amp Amex 1 800 826 7623 B amp 1NC 10517 Upton Circle Bloomington MN 55431 SATELLITE TV FREE catalog systems upgrades Houston Uni den Chaparral etc Save 55256 SKYVISION 2008 Collegeway Fergus Falls MN 56537 218 739 5231 CABLE TV secrets the outlaw publication the ca ble companies tried to ban HBO movie channel Showtime descramblers converters etc Sup pliers list included 8 95 CABLE FACTS Box 711 Pataskala 43062 BUSINESS OPPORTUNITIES YOUR own radio station AM FM TV cable Li censed unlicensed BROADCASTING Box 130 F 10 Paradise CA 95967 For 25 years our people have endured long hours and tough working conditions for no pay And 9 out of 10 would do it again TO FIND OUT WHY call 316 263 2100 Or write REACT INTERNATIONAL INC 242 Cleve
51. The WM D3 can also be connected to most component sys tems for either record or playback pur poses which adds further to its versatility As impressive as its performance is the unit is not without drawbacks The record er player s design intended to pack the most audio electronics into the smallest space possible dictates that the cassette is loaded into a door covering the back of the machine a configuration that almost in vites breakage Not so much flimsy as delicate the cassette holder door is a design feature long overdue for retirement The case too deserves to be described as cheesy raising the question of whether it will provide even a modicum of safety for the fragile electronics inside The suspicion grows that manufacturers aren t nearly as interested in case du rability as consumers are If only by virtue of their portability and size most mini ature recorder players probably come to an unnatural end as represented by sud den falls of sharp impact Even supplying carrying case isn t an answer Consum ers have a tendency to discard or lose the often unattractive fabric containers and trying to operate a recorder when it s fully dressed can be clumsy and cumbersome A budget priced unit not worth having at any price and a high performance model barely encased in plastic suggest a marketing cynicism that takes the pleasure out of consumer audio use Miracles of the audio variety come in small packag
52. VISUAL TELEPHONE DIS PLAY LU 500 Manufactured by Mitsubishi Visual Telecom Division 3350 Scott Blvd Building 49 Santa Clara CA 95054 Price 399 The future s finally here it just took longer than expected to arrive And unfor tunately up close it s not quite the marvel that was once promised Of course the future we re referring to is the picturephone first unveiled by AT amp T at the New York World s Fair some 24 years ago The 1964 picturephone was reputedly capable of transmitting and receiving moving images The Mitsubishi Visual Telecom product the Visite Visual Tele phone Display is limited to stills snapshots really and during transmis sion five or six seconds per 2 by 31 4 inch image callers can t talk In fact if one party is talking when the send button is pushed the audio overrides the video The Visitel connects to a telephone like an answering machine or other accessory The phone is connected to the Visitel with VOLUME 1 NUMBER 8 a line from the visual display unit going to the phone outlet The visual telephone display is also plugged into an electrical outlet with a supplied AC adapter Operation is as simple as installation sliding door over the instrument s video camera lens turns the unit on or off Opened half way the sliding cover allows the unit to receive images but not to send them Under the Visitel screen two con trols adjust brightness A view
53. a knot such as an underwriter s knot in it or consider using strain relief Attach a plug to the cord turn the box right side up and you re done You may have a little trouble finding a magnet small enough as well as strong enough to jump with any degree of energy The one in the photos is only long If you do not wish to use the supplier mentioned in the Parts List then you can make a small magnet from a larger one you may already have Wrap it in cloth or paper and break it into smaller pieces with a pair of pliers and a vice Do not bang on the magnet as that reduces its strength Do not use a magnet that you might want to use for some other purpose What you have built is very similar to bulk tape eraser or degausser The alternating field will weaken and eventually neutralize the power of the magnet EJ 8861 H38O100 eo T By Marc Ellis M A little housekeeping i is worth a lot of troubleshooting LIDURING THE LAST COUPLE OF early to be concerned about the oscilla months we ve been working on the restoration of a Zenith 75232 BC SW set The set is a large table model radio with some very interesting features in cluding tuning dial of unusual and beautiful design Called a shutter dial it contains a mechanical arrange ment to automatically display the cor rect set of calibrations for the band that is
54. a carriage return Endif End of if then statement Exit If C 0 If A has all been sent then exit the loop is assigned the left character of ASCII value of B is output to the serial port AS Right A C 1 A AS less its left character Loop The end of a loop Goto Start Goto the beginning and start over BS Left A Out 1 Asc B as spelling practice programs It also adds spice to computer games The synthesizer is great entertainment for company Sim ply write a dialog program and then pretend to be carrving on a conversation with the computer Your friends will be amazed that your computer is so intelligent 1 have also compiled programs and set them up to run at boot time so that the computer greets me when I turn it on asks me tor a password etc The converter chip that the project is built around does a nice job with single letters and numbers For example send it a 7 and the voice says seven send it an R and the voice says etc It will not however handle a long number If you send a 609 it will say six zero nine and not six hundred nine The chip is also great for sound effects Send it a long string of ss ss ss ss ss and it sounds like a steam locomotive send bb bb bb bb bb bb and you get a machine gun effect With a little imagination and experimentation you re sure to come up with many other interesting sound effects have mentioned
55. a con necting cable The board is installed adjacent to or near the existing disk controller The normal connection from the existing controller is moved to the Deluxe Option Board and the supplied cable is connected to the existing disk controller If your computer has an all in one motherboard that also contains the disk controller you simply move the The user simply moves the jumpers to the appropriate terminals controllers The Deluxe Option Board gets around the protection by function ing as its own disk controller without any quirks Unlike conventional copy ing schemes that copy only data from the source to the target disk the COPYIIPC system copies everything sector IDs gaps sync bytes address marks and clock bits The target copy is as exact a copy of the source disk as is possible Because the Option Board provides a bit by bit the same computer can also disks in standard format for the Atari and Apple comput ers However not all protected Atari and Apple format disks can be copied Also flippy disks cannot be copied and keep in mind that not all IBM drives are capable of reliable reads and writes of the Apple format Drives The Deluxe Option Board works in either a one or two floppy disk system having 360K 720K 1 2 Meg or 1 44 Meg drives There are several limita tions when using 3 5 inch drives among them the source and target
56. agencies Scanning those services VHF frequen cies in our vehicles alerts ARES mem bers to events for which our special emer gency communication services may be requested In many instances monitor ing those frequencies has helped us gain valuable lead time as we gear up in ticipation of the official Emergencv Callout that is usually initiated by the Santa Barbara County Sheriff s Office We hams have those transceivers we use them and it is highly unlikely that we will stop using them due to indis tinct and ill directed politics enjoy Saxon on Scanners as do the entire magazine Hands on Elec tronics gets a good reading every month then passes on to others who enjoy at least as much as 1 do W G H Santa Barbara CA ELECTRONIC WORK CENTER complete combination to make pie areas more efficient and manageabic Circuit Board Holder gently E firmly holds up 10 12 NES Add our Standard Base moves E three planes Tray Base Mount parts wells and Solder Station sc centers wire and holds iron 9 angle for a great combo Mode 324 5195 nics supplier or contact PanaVisc vou 2850 E 29th Street 213 595 7621 See your local electro for the source nearest Panavise Products Ine Long Beach CA 90806 8861 H38O1DO wd JDR Microdevices Complete customer satisfaction superior service friendly kn
57. already own a 5 2 can learn how to realize their system s maximum po tential The differences and similarities of the new OS 2 and PC DOS 3 3 operating Systems are explored to aid readers in the selection of software and hardware prod ucts that wil best meet their PS 2 needs The book also describes how to communi cate and exchange data between a new PS 2 and an existing PC with a minimum of difficulty IBM PS 2 Handbook contains 358 pages and costs 19 95 It is available from Que Corporation P O Box 90 Carmel IN 46032 Tel 1 800 428 5331 CIRCI E 94 ON FREE INFORMATION CARD EXPERIMENTS WITH EPROMS by Dave Prochnow Erasable Programmable Read Only Mem ory devices EPROMS are dual in line pack ages capable of holding any user supplied programming in a nonvolatile fashion yet they can be quickly erased at the user s discretion and reprogrammed to perform a different function Virtually any design that uses microprocessor control or requires ex ternal data for its operation can be easily modified to accept EPROM programming Incorporating EPROMS into digital circuits isn t difficult if you have an EPROM programmer an EPROM eraser and prac tical instructions Experiments with EPROMS provides all three The book be gins with a detailed explanation of under lying theory including discussions of digi tal memory binary codes mathematics and logic then goes on to desscribe fifteen EPROM projects inclu
58. amateur radio If you absolutely loath computers please bear with at least this one month Computerized Morse Code Two amateur radio products intended lor Morse code operators are shown in the photos Both were originallv offered to the amateur market by Microlog In corporated but are now offered by G amp G Electronics 8524 Dakota Drive Gaithersburg MD 20877 301 258 7373 SWL cartridge is designed to plug directly into the ROM cartridge slot of the Commodore 64 and 128 per sonal computers A line from the re ceiver s headphone or speaker jack is connected to the analog input of the SWL cartridge The SWL cartridge equipped Commodore when tied to your receiver can receive decode and display both Morse code and radi oteletype RTTY signals The SWL cartridge acts like nar row bandwidth about 50 filter necessitating careful tuning of the re ceiver Once it s installed the C 64 C 128 speaker beeps in step with the received code or RTTY signal when the receiver is properly tuned At that point the letters represented by the sig nal begin to flicker across the TV or monitor screen With the SWL car ridge it is possible to become a fast er CW operator than natural ability would allow used the SWL cartridge for about month while preparing this column t IS a little touchy to learn to operate because of the narrow bandwidth filter characteristic
59. appropri ate tool for manipulating graphic elements So in this article we ll look at several such tools generically called pointing devices including mice trackballs and others And we should point out that graphics programs are not the only ones that can benefit from pointing devices Many text mode programs QuickBasic 4 0 DESQ View 2 0 Grand View and BookShelf for example now come with interfaces that allow you to use pointing devices to accomplish your tasks Pointer Basics If you re picky about the feel of your keyboard you re liable to be even pickier about your pointer because of the sensitive nature of the tasks to which pointers are usually applied When you re moving a cursor on a screen with 1000 dots in both directions you want something that doesn t jerk every time you move it Jerkiness may be due to a poorly designed or manufactured device but it may also be due to the size or shape of a device and how it fits in your hand So if at all possible try before you buy You ll also want to consider several other points before buying the interface type the underlying technology the included documentation the number of buttons the pack aged software and the device s power source The Interface Many pointing devices come in two versions serial and bus A serial version requires use of a standard RS 232C serial port a bus version provides its own interface card Some people feel that bus versions provide
60. but after only a little ex perience the tirst evening I learned to tune the receiver very easily Although Jeff Goldman of G amp G told me that his engineers are working on transmitting version it took little effort to receive on my SWL C 128 combo while transmitting the old fashioned way with either my Vibroplex bug or MFJ Electronic Keyer I have an older Microlog ASCII to CW key board that also transmits the letters for me The other Microlog product now of fered by G amp G Electronics is the Morse An SWL equipped Commodore 64 or 128 when tied to a ham station can receive decode and display both Morse Code and radioteletype RTTY signals The Morse Coach in conjunction with a C 64 or C 128 computer is designed to provide intense Morse Code practice It offers three modes of operation alphabet practice and speed test Coach That plug in cartridge con junction with a C 64 or C 128 comput er is designed to give you intense Morse code practice and is almost guaranteed to help you improve your speed The Morse Coach teaches code from the ground up And once you ve gained some degree of proficiency at recognizing the transmitted code you use it to increase your speed pro gressing at your own pace rather than at pace set by a class There are three modes of operation offered by the Morse Coach alphabet practice and speed test And it has a variabl
61. change if one or more parameters are varied The second reason for this type of math is circuit design Whenever you wish to create a new circuit to perform specific function you must be able to specify what you want then work backwards to synthesize the circuit that will give it to you The math lets you do that on paper Circuit analysis in electronics is really not af that difficult Typically a great deal of it can be done with the basic electrical laws you no doubt learned somewhere along the line Specifically am speaking of Ohm s law and Kirchhoff s laws Both are simple mathematically and very Voltage Sources Almost any electronic circuit can be represented by the simple equivalent circuits shown in Fig 1 The circuits con sist of a voltage source with an internal impedance and some type of load In Fig 1A the source is a battery with a voltage of V and its internal resistance Rs connected to a resistive load R A simple example might be a flashlight where the battery represents some 1 5 volt D cells and the load repre sents the light bulb Another example might be where the battery Fig 1 represents a DC electronic power supply with its internal resistance while the load represents one or more electronic Circuits In Fig IB the voltage source is an AC generator with its internal impedance connected to a load That might represent any number of circuits For example the AC generator might represent
62. connection as the problem s source You may assume the motor is defective when correct voltage is found at the motor terminals However zero volts at the motor tells you nothing since it could indicate trouble with the supply circuit shorted motor windings or both An intermittent or erratic motor can be tested for by using an external DC voltage applied to the motor terminals Some times rotating the motor shaft may start the motor indicating intermittent operation Replace the motor In electric motor control circuits the external voltage test may indicate a de fective motor or control circuit A variable or universal power supply source is ideal in locating problems with motor control IC s or transistors Those low voltage control circuits are found throughout the world of portable cassettes compact disc players and camcorders Fig 2 SW2 2 143 C902 220 AUTO CASSETTE MOTOR Fig 1 Suspect a poor switch contact or open isolation resistor when no voltage is measured at the motor terminals in the audio cassette player LOAOING MOTOR FROM CONTROL IC 10 7V Fig 2 improper voltage found at the loading motor in a CD player may be caused by a defective voltage supply A Variable DC Source A 0 5 volt variable voltage source in a cabinet with some fixed voltage sources at 12 15 and 25 volts could be used to check most DC motors If you build the Motor Voltage Box shown in Fig 3 the 1
63. converts it into allophones that are recognized by the speech synthesizer integrated circuit word Don the voice will say done but if you enter dawn then Don will be pronounced correctly The CTS256 AL2 can be configured in a variety of ways For example the chip will work with parallel or serial input with a selectable baud rate with internal or external RAM and will output after a carnage return only or after any non alphanumeric delimiter I set the circuit up to work with a serial input because my computer s modem port was free I also decided to go with the external RAM mode and add a memory chip The internal RAM input buffer of the CTS256 AL2 will accommodate words 19 characters long or less or a phrase of no more than 26 bytes If you try to send more the synthesizer will lock up and require resetting By using the external RAM I was able to send just over a screen of text using my Atari ST without any problems SPO256 AL2 is speech processor that requires the paralle input of a code that corresponds to a particular allophone Those allophones are then linked together to form words Without the help of the CTS256 AL2 the speech processor must be programmed manually That can take hours of trial and error programming to get even a simple phrase to sound good A pin out diagram of the SPO256 AL2 integrated circuit is shown in Fig 2 How It Works The schematic diagram of the speech synthe
64. deal the personal computer makes it a game for all Note Not all transceivers are suit able for RTTY operation Some lack the capacity while others simply cannot withstand the higher average power output levels required So check your owner s manual or the manufacturer s literature before going on RTTY Packet Radio With the addition of a Terminal Node Controller TNC and a personal com puter your rig is ready to join the high tech end of amateur radio packet radio I plan to acquire a TNC for either the Apple or Commodore 128 in the near future report on that venture in some future column If you haven t seen the packet revolution then stand back it s pretty neat Amateur Rigs and Computers The big buzz word used in dealing with computerized anything is interfac ing That is the joining of a personal computer and some other equipment in our case an amateur radio station Although some special interface pro tocols exist especially among amateur transceiver manufacturers many of the after market interfaces expect to see a standard RS 232C serial port on your computer The MFJ 1278 Multi Mode Data Controller unit offers seven modes of operation Packet ASCII RTTY BAUDOT RTTY WEFAX SSTV and Contest Memory Keyer The RS 232C feature can be added to any or Apple computer by installing the proper RS 232C I O card also called a serial port serial commu nic
65. far beyond the laboratory measurements of gravity that are generally limited to lengths of a few inches The discovery of gravitational variations would have a significant impact on several branches of modern physics and would require the recalculation of the masses of planets and stars Geophysicists Mark A Zumberge from the University of California San Diego Institute of Geophysics and Planetary Physics at the Scripps Institution of Oceanography and Mark E Ander from the University of California Los Alamos National Laboratory will lower a gravity meter down a hole bored into the Greenland ice cap to accurately measure the gravitational constant first determined by Sir Issac Newton more than 300 years ago The universal constant is com monly called big G by physicists to distinguish it from local gravity little g which varies continually with rela tion to the surrounding mass The Newtonian gravitational constant G is one of the most important and least well determined of fundamental physical constants If the effective gravitational constant can be proved to be dependent upon distance it will mean that a fifth force exists in nature commented Ander Such finding could assist physicists in the pursuit of a unified field theory that could tie together the known forces of gravity and electromagnetism and the concepts of strong and weak forces two factors of nuclear particle physics It will also profoundly effect other b
66. for the Sinciair Step by step ap proach includes practical examples A TRONIC CIRCUITS FOR THE COMPUTER CON TROL OF ROBOTS 7 50 Data and circuits for intertacing the com puter to the robot s rnotors and sensors BP134 EASY ADO ON PROJECTS FOR COMMOODORE 64 VIC 20 BBC MICRO amp ACORN ELECTRON 6 95 Picture digitizer light pen model comro ler and more ie Goi Tour Compute Programs BP118 PRACTICAL ELECTRONIC BUILO ING BLOCKS Book 2 5 75 Amplihers tor all kinds lo add lo the Circus trom Book 1 of this senes 1 6P169 HOW GET YOUR COMPUTER PROGRAMS RUNNING 5 95 Have you ever written your own rams only lo find that ey do not work This book shows you how to find errors BP80 POPULAR ELECTRONIC CIR CUITS Book 1 5 95 More circuits for hoo byists Audio radio test Music househboikd and more BP98 POPULAR ELECTRONIC CUITS Book 2 5 95 More useful cit cuts None of these projects duplicate those n 1 of tus senes SORRY No orders accepted Number of books ordered C
67. here As for software had no trouble running the mouse using the MOUSE COM driver that comes with the Microsoft mouse and with MicroSpeed s PDA driver more on that following KeyTronic The KB5153 is an AT style keyboard with a digitizing tablet embedded in the right side The digitizing tablet can be programmed to emulate regular keyboard keys mouse mo tions or both Resolution is low in key emulation mode so you can press the pad with your fingers In mouse mode however you use a plastic stylus to traverse the pad Key Tronic supplies software drivers for running PageMaker and Ventura Publisher with the keyboard a Microsoft mouse emulator and other programs for creating your own sets of keyboard emulations The KB5153 is more expensive 250 than the other 1 4 1 me n 3 tw ET The KB5153 starts with a basic AT style keyboard and adds a programmable digitizing pad Plastic overlays show which portion of the pad emulates keystrokes and which emulates mouse motions You can use the setups provided by KeyTronics or design your own specific layouts devices discussed but it needs no extra desk space The keyboard itself has a nice feel not as clicky as an IBM but not mushy like most cheap clone keyboards If you need a keyboard and a mouse this quality product is worthy of consideration MicroSpeed This company has
68. in use The radio also features flywheel atded vernier tuning a magic eye tuning device and individual in dicator scales for the tone control vol ume control and bandswitch introduced the set in the August column giving a fairly complete phys ical description and noting some of the Instability of that kind can easily be caused by poor ground connections at tube shield cans and would be re medied by the deep cleaning that was to come next Which brings us to the point of this month s column It doesn t pay to get too analytical about troubleshooting an old set until you ve given it a thorough cleaning lightened and readjusted all loose com ponents especially tube shield cans and subjected everything to a searching inspection A preliminary inspection of the chas sis showed that the radio was physically intact but suffering from the effects of quick and dirty servicing and ANTIQUE RADI M9 ment Aside from the usual dust and grime could see evidence of corrosion and oxidation on both painted and bare metal surfaces While there was nothing that wouldn t clean up nicely the set was obviously never going to look brand new again But it would at least be very presentable Checking Topside Looking at the top of the chassis I could see that both tube shield cans were improperly mounted on their base
69. increase it Slowly rotate R4 and notice the speed of the motor Rotate the control until the correct voltage is applied and the music sounds normal If the music sounds erratic and uneven suspect a loose belt or dry capstan flywheel assembly 8861 H38OLOO o Es HANDS ON ELECTRONICS J o CASSETTE SPINDLES Although the motor terminal wires can be found out in the open for testing the boom box cassette player assembly must be removed before removing the motor mounting screws MOTOR OUNTER CAPSTAN FLYWHEEL Remove the motor drive belt and rotate the motor pulley to see if the motor starts to rotate with correct voltage applied Replace the cassette motor if it starts up after hand rotation or seems to pull as it is rotated MOTOR EELT PULLEY Auto Cassette Mctors The auto cassette player may operate directly from the car battery or a voltage regulator circuit The voltage measured at the motor terminals may vary from 12 to 14 volts If there s no voltage to be measured at the motor terminals suspect a poor switch contact or open isolation resistor When you see an improper voltage at the motor suspect the voltage control circuitry Rotate the motor pulley and notice the magnetic pull of the armature Doublecheck the motor by removing the motor terminals and connecting them to the 12 or 15 volt DC output of the box If the motor takes off suspect a defective motor control circuit Let he motor run for seve
70. is right with the world or so you thought The morning before the big event trash collection day you open the front door to find that all of your efforts were for naught Neighborhood strays have chosen the sidewalk in front of your house as their restaurant and made your neatly stacked refuse the main course It s not that you mind their having wrangled a meal from your discards but did they have to make such a mess This month the Circus deals with a number of electronic critter ridder Circuits designed to electronically erad icate just about any uninvited diners Now don t get the wrong idea because dearly love our animal friends and wouldn t build a circuit to harm or mis treat a single one But there are some places and times that man s best pal should be restricted from a given area For instance if Mama s flower garden is in constant attack by your favorite pooch and you are getting all of the flack for Rover s tunneling don t lose control and set steel traps or fire off a scatter gun Instead draw your solder ing iron and build one of our circuits to humanely guide Rover out of Mama s hair and restore peace and tranquility to your home Doggies aren t the only critters that these circuits are designed to move out actually just about any living creature with ears won t stay around for long in an area where one of the eradicator cir Cults 15 operating Audible Critter
71. jacket pocket But there seems to be law of diminishing returns at work Those magic machines pack a million dol lar sound system into a dime store case The combination of delicate innards and flimsy protection have evolved into a 48 2 GIZMO In terms of amusement the Visitel s low resolution makes visual trickery possible If the correct photos in terms of size and clarity were used a caller could claim to look like Paul Newman or Elizabeth Tay lor offering a carefully held picture of the star as proof Similarly a photograph of a spectacular room clipped from a design magazine could be used as a backdrop Various combinations of still and live action might also be used in pursuit of all manner of visual illusion An unlikely consumer device we imag ined unlikely buyers for it apart from the legions of gizmo fanatics and fans Par ents who are concerned their kids aren t spending enough time on the telephone might want to get a pair of the units Re clusive eccentrics like the late Howard Hughes might appreciate a limited visual dimension to add to their limited audio connection with the world Visitel cer tainly won t inadvertently reveal any se Crets via its camera In fact caller s control over whether to send an image or not overcomes one of the obstacles that dogged the original pic turephone Many commentators worried about what that new device might do to the concept of privacy
72. made up of R1 and R2 while the other is Fig 12 Bridge circuits are difficult to solve with more basic methods However they can easily be analyzed using Thevenin s Theorem and a little math R4 89 Fig 13 with a bridge circuit the first step is to remove the load from the circuit before analysis 129 A Vs SHORTED R4 89 1222 R34 480 Fig 14 shorting the voltage source the circuit looks a little strange A but that can be resolved by rearranging B Then we break the resistances down into simpler equivalent forms before final analysis 8861 H38OLOO HANDS ON ELECTRONICS e e made up of R3 and R4 What we wish to know is the voltage between terminals A and B But to find it we must first determine the voltage at A with respect to ground and the voltage at B with respect to ground To do that we can simply apply the voltage divider equation given earlier The voltage at point A with respect to ground V4 is computed as follows Va 7 V sRZ RI 2 15 12 6 12 15 12 18 15 0 6666 10 volts The voltage at point B with respect to ground is computed in exactly the same way Vy VsRA R3 R4 15 x 8 8 12 15 8 20 15 4 volts We now know the voltages at A and B with respect to ground The voltage directly between A and B is simply the difference between those two voltages From that Vg which i
73. modern of subject matter Your very first module takes you right to the heart of basic circuit concepts and gets you ready to use integrated circuits to build a digital oscillator Then you ll verify the operation of different electronic circuits using a light emitting diode LED And each successive module brings you up to speed quickly clarifying the latest With this essential hands on experience using actual electronic components you master prin ciples that apply all the way up to tomorrow s VLSI Very Large Scale Integrated circuitry Discover Explore tions robotics experience that offers in today i ig a Experience for Yourself from digital logic 3 d 15 Day Trial and micro ee 4 4 A In all ways the Contem processors to porary Electronics Series is data communica 5 Ax 5 an exciting learning lasers fiber optics y T you the quickest and more P and least expen sive method Unique L available to Combination of UNE 5 Interactive Instruction py Materials Makes xm disc dr ing Fas with hands on Learning Easy experience Laboratory experiments With your first module you ll build this solderless huc 6 breadboarding system As you add additional boards agi vividly illustrated text our first you create increasingly complex circuits easily and y APE peeve COMNIS quickly bringing today s electro
74. modular kit of parts brings computer age gadgetry to the workbench LJAFTER HARD DAY S WORK HAR ried husband unlocks the front door to his home only to find that his wife is not home He s not concerned however In stead he removes his coat glances through the mail and presses a button on a small plastic box A familiar voice rings out Honey I ll be back in 10 minutes Picking up the kids at the skat ing rink Freshen up and supper will be ready by six His wife had left him a recorded mes sage in a Digital Voice Record Play back unit that he built himself mostly from a kit of parts The project was the third that he had ever tried and his friends now think he should head up the space program We don t agree with his friends but we do know that you can build the same project and others based on it at a low cost but with maximum impact on your family and friends If you want your friends to think that you should head up NASA read on Specifications The Digital Voice Record Playback Module K2653 can store up to 10 12 seconds of speech in its RAM memory Voice quality of the played back sound does diminish with the length of the preset maximum playback time but the voice is always intelligible The module requires a regulated 9 volt DC power supply The standby power is 0 5 milliamperes The play back maximum current drain of 300 milliamperes is mainly expended in the audio output stage in deliv
75. mounted components The method used to mount the board in the cabinet is left to TABLE 1 CARD EDGE CONNECTOR FINGERS Finger Number Connection 2 To Ground To 5 Volts 10 To Speaker SPKR1 11 To RS 232 Transmitted Data Pin 2 13 To R10 Wiper 16 To 1 18 To R10 19 To RS 232 Signal Ground Pin 7 20 To S1 Ground 21 To Speaker Ground 22 To R10 Ground C6 NT 1 zx 45V 1 OTON R10 V VOLUME AA 2 J RESET 421 _ SIGNAL i 22 GROUND Fig 5 Mount the components on the printed circuit board following this layout Note that the board is single sided While that means that the board is easier to make it also means that an unusually high number of jumpers must be installed Be sure that all of the jumpers shown are installed or the circuit will not work 8861 H38O10O0 HANDS ON ELECTRONICS the builder In the prototype 22 or 44 contact card edge connector is mounted in a home made right angle bracket that is secured to the bottom of the case The board is inserted into the connector and supported at the other end with non conductive stand offs A less elegant but still acceptable mounting technique would be to support the board on four non conductive stand offs and tack solder the board finger connections The prototype shown features some extras that not included in the schematic Those are an on off toggle switch a power on LED indicat
76. only tew of the numerous applications for the circuit If you have any external monitor or control hardware attached to your computer such as a burglar alarm a fire alarm a real time clock a model railroad control etc then this addition to your system will be great for alerts warnings or just plain fun B LI SPARK GAP VOLTAGE CAPACITOR SECONOARY COIL PRIMARY COIL HIGH TVAC 4 STEP UP TRANSFORMER HANDS ON ELECTRONICS o D2 117 VAC R3 R6 R7 02 10 R4 10K 1K MJE34 10K a 01 555 2N39 OSC m R1 R8 4702 gt i C2 2K 47 C5 lt 1500pF GAP 11 2 5 R9 DOU PRI 1002 T2 10022 03 4 2 2N3055 x 7 RH 10082 R12 1000 Fig 2 Our updated version of the Tesla experiment uses 18 volt 2 ampere transformer T1 a full wave bridge rec tifier consisting of D1 D4 and filter capacitors C1 and C3 to supply operating power for the Coil s circuitry current to transistors Q3 and Q4 to drive those components into full saturation The primary winding of T2 an automobile ignition coil is connected in series with Q3 and Q4 and across the power supply Transistors Q3 and Q4 operate like a toggle switch connecting the coil across the power source at the rate and on time set by UI That high current pulse generates a rising and collapsing held across the primary winding of
77. parts kit for vocational schools educators and technicians This is the same material used in the Digital and Microprocessor Course during EIA s summer work shop programs These workshops are organized by the Consumer Electronics Group and co spon sored by national service organiza tions and state departments of vocational education Parts and components are con tained in a lightweight tool box with individual compartments It includes a breadboard power sup ply pre dressed jumpers resistors PLEASE COMPLETE ORDER FORM FOR PARTS KITS AND BOOKS Send to EIA CEG Department PS P O Box 19100 Washington D C 20036 sor section but other components will have to be acquired as listed in the Introduction to Exercises Individual and classroom size quantities are available at the fol lowing cost quantities 1 9 69 95 each quantities 10 19 67 95 each and for quantities 20 or more 64 95 each cost includes shipping and handling The kits will also include the Digital and Micropro cessor Course book Additional books are available at the cost of 2 00 per copy Parts Kit Quantity Amount Total OP 69 95 each creek 6 cC 67 95 each R 64 95 each Additional Digital Microprocessor Course Books 2 00 EE Total Amount Enclosed Electronics Paperback Books BP173 COMPUTER MUSIC PROJECTS 6 95 Shows how to
78. the bearings will provide extra hours of operation Usually with a frozen bearing the motor pulley can not be rotated If the motor bearings are gummed up with old grease wash out both end bearings with cleaning fluid When improper voltage is found at the motor terminals check the motor switch isolation resistor or power supply Mark down the color of both motor terminal wires before removing Apply the correct voltage to the motor using the Motor Voltage Box Sometimes by applying an external voltage and watching for motor rotation you can tell if the motor operates intermittently or slows down or if it rotates at a constant speed If the motor appears normal check the control C or processor for improper operating voltage Testing Portable Decks Portable cassette player motors are often very small and operate on very low voltage Check the total battery voltage to determine the approximate operating voltage Suspect a dirty leaf switch or shorted windings when no voltage is found at the motor terminals Do not overlook a stretched or dirty motor belt on finding slow or erratic speeds Determine the condition of the small motor by connecting it to the 0 5 volt DC output of the Motor Voltage Box Connect the positive lead of the box to the positive motor terminal That will prevent the motor from rotating back wards and throwing out excess tape from the cassette On any small low voltage motor always start with no voltage and slowly
79. the output of an amplifier with its internal imped ance Rx while the load may represent a speaker Another example is that the voltage source might represent the class C output amplifier of a CB transmitter with its Output imped ance connected to a 50 ohm load which represents an anten na Those are only a few examples but you get the idea Almost any electronic circuit be simplified until it i represented by an equivalent circuit similar to those shown in Fig 1 In some cases you will hear the internal resistance NETWORK ANALYSIS amp THEVENIN S THEOREM By Louis E Frenzel When you ve got a circuit schematic with enough interconnections to make a traffic planner ill how do you analyze it without getting ill Network analysis easy to understand and apply See the sidebar entitled Ohm s and Kirchhoff s Laws for a quickie review of those important electronics laws When the circuits are essentially simple series and parallel circuits all you need is Ohm s and Kirchhoff s laws to analyze and solve them completely But as the circuits get more complex the laws while they sull apply are more difficult to use In some cases complex circuits defy analysis or design That s where special circuit theorems come into play Over the years many different techniques have been developed for analyzing and designing electronic circuits The theorems are really not any more diftrcult to understand or apply than Ohm s or
80. the principles of fiber optic de sign Model JE315 includes fiber optic cables and connectors and costs 29 95 For more information contact Jameco Electronics 1355 Shoreway Road Belmont CA 94002 Tel 415 592 8097 for orders only 415 592 8121 for all other inquiries VHF Marine Radio Kenwood s TKM 407 VHF marine radio is designed for durability and re liable performance in the marine en vironment ts high impact corrosion resistant plastic case covers a die cast metal chassis A large heat sink protects the components from vibration and damage The compact TKM 407 provides 25 watts of power output For use on FCC restricted channels the watt low power position can be used It has large LCD for optimum readability in sunlight and is illuminated for night viewing The display can be adjusted with a dimmer switch The front mounted speaker is water resistant See MEG 4 lt CIRCLE 45 ON FREE INFORMATION CARD All U S Canada and International Marine channels factory pro grammed The TKM 4077 also re ceives up to ten weather channels and can store as many as 30 other channels The radio has a dual watch feature that monitors Channel 16 for approximately a half second every 2 seconds allowing the user to remain constantly in touch with Channel 16 regardless of the chan nel being used The TKM 407 has three scanning modes Dial scan for
81. this issue It s a slight one to be sure and one that might not be noticed by many of our readers See if you can find it Next issue will make another change and I ll put that one right on the front cover Remember change is inevitable Julian S Martin KA2GUN Editor SA Volume 5 No 10 October 1988 Larry Steckler EHF CET Editor In Chief amp Publisher Art Kleiman editorial director Julian 5 Martin KA2GUN editor Carl Laron WB2SLR managing editor Robert Young associate editor Herb Friedman W2ZLF associate editor John J Yacono associate editor Brian C Fenton associate editor Byron G Wels K2AVB associate editor Teri Scaduto assistant editor Kathryn Campbell editorial assistant Ruby M Yee production director Karen S Tucker production manager Robert W Lowndes editorial associate Marcella Amoroso production assistant Andre Duzant technical illustrator Injae Lee assistant illustrator Jacqueline P Cheeseboro circulation director Nancy Estrada manager HOE Bookstore 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 Cover photography by Diversified Photo Services Composition by Mates Graphics Advertising Sales Offices listed on page 105 Hands on Electronics ISSN 0743 2968 Published monthly by Gernsback
82. use your home computer to produce electronic music Many circus Mostly jar gon tree BP176 TYV DXING FOR THE ENTHUSI AST 7 95 Practical authordalive intro to this unusual aspect of etec troncs 812 gt 11 in 144 pp Becrete ot the introdottien Computer COMMOOORE 64 Pragremmng Terminology the Et 1 iuptaned TM GREAT PAPERBACKS AT SPECIAL PRICES PCP103 PRACTICAL MIDI HANDBOOK RADIO S FIRST TWO DECADES Suk gt i as BP195 INTRODUCTION TO 9 95 Explains what RFTD RADIO S PCP102 SATELLITE 9 95 MID the Musica FIRST TWO DECADES INTRODUCING A definitive introduction to Interface can do 3 50 This story of OtGITAL AUDIO the subject written tor the and how can put it radios earty days 9 95 DAT and professional engineer to work Covers makes tor fascinaling sampling What 15 electronics enthusiast of Keyboards drum reading Spark involved m the digital others who want to know machines sequencers mixers guitars and computer music 8P135 SECRETS OF THE COMMODORE 64 5 75 Masses ol usetul into and program ring tips not found in any users manual BP130 MICRO IN TERFACING CIRCUITS BOOK 1 5 75 Practical add ons transform your Computer mto control or measure ment equipment J8P183 AN INTRO DUCTION TO CP M 6 95 To run and use p
83. will not provide a constant output voltage for all load values Changing the load resistance invariably will change the amount of voltage supplied by the voltage source The reason for the change is that all practical voltage sources have a built in internal resistance or output impedance Take a battery for example It is about as close to a perfect voltage source as you can find in practice You can almost connect any value of load resistance to a typical D cell and its output voltage will remain at approximately 1 5 volts The reason for that is that the battery has an extremely low internal resistance output impedance It is usually so low compared to the load resistance that it is negligible and so it is considered to be zero in most cases But as you make the load resistance smaller the internal resistance becomes a larger percentage of the total circuit resistance It is at that point that decreasing the load resistance causes the output voltage to drop consider ably Let s take a look at that phenomenon in a little greater detail Figure 2A shows a voltage source with its internal resistance lt With no load connected to the battery no current will flow With no current flowing through the internal resistance no voltage drop will be produced across it For that reason the voltage at terminals and B will simply be the natural voltage produced by the battery That is known as the open circuit voltage which is just Vs
84. 0 ohm R8 4700 ohm connections are made properly and that all parts are correctly soldered onto the printed circuit board install the inte grated circuits in their sockets TALKIN BACK PLAY RECORD 9 O 54 SLOW 7 55 TWICE MICI RV2 CONOENSER MICROPHONE REC VOLUME R9 2700 ohm R10 R11 10 000 o0hm R12 390 ohm R13 1 5 megohm 14 820 000 R15 10 ohm RV1 250 000 ohm flat PC mount trimmer potentiometer RV2 10 000 ohm vertical PC mount trimmer potentiometer RV3 47 000 ohm vertical PC mount trimmer potentiometer OTHER PARTS AND MATERIALS LD1 Light emitting diode red MIC1 Microphone condenser Printed circuit board IC sockets 15 PC mount terminal pins plastic shafts for RV2 and RV3 etc ADDITIONAL PARTS The following parts are required for this project but not supplied by the kit manufacturer B1 9 volt DC 300 mA power sup ply or six 1 5 volt D cells Fi 0 5 amp fuse with in line Connect a regulated 9 volt DC power supply to the printed circuit board pads labeled 9 and 9vpc Pay care fui attention to voltage polarity The 1 VAC 9 0 300 REGULATED POWER SUPPLY OIGITAL VOICE RECORO PLAYBACK MODULE RV3 VOLUME Fig 2 the printed circuit board has been completely wired and inspected for cold solder joints and solder bridges the external circuit is connected
85. 00 kilowatt Radio Nederland relay stations on the West Indian island of Bonaire Broadcasts are aired every Sunday night 0230 UTC Mondays on 6 165 and 9 590 kHz and repeated at 0530 UTC on 6 165 and 9 715 kHz The Philips test broadcasts had start ed a year earlier but in 1928 a young announcer named Edward Startz began the weekly program that he called Happy Station And over the decades millions of listeners were able to keep in touch with the Dutch through Stanz broadcasts His verbal trademark was a weekly invitation to listeners to join him for a nice cuppa tea Eddy Startz retired in 1970 ending one era but beginning another He was replaced bv 32 year old Dutch announcer Thomas Hendrick Meijer who along with his family es caped the Nazi occupation of Holland As a pharmacy student he quickly de cided that his interests led in another direction to music and the theater In 1965 he joined the staff of RN and for international audiences changed the Dutch 71 spelling to y becoming Tom Meyer Five years later when Startz left Meyer became the host of the vener able The Happy Station program Eighteen years later he s still working the show though he still has a long way to go to match his predecessor s 41 year tenure at the station something for everyone In keeping with the harmony theme the program steers clear of topics like
86. 1 Hal Tronix 95 9 Halted Specialties 13 Hands on Bookstore 102 18 JDR Microdevices 6 12 Jensen 23 14 Electronics 17 16 Mark V Electronics 23 McGraw Hill C E D 9 Midwest Electronics 105 13 NIDUSER 2 22 101 uu 00000000 1 21 Pacific Cable 18 7 CTI The Datak Corporation 2r ADVERTISING SALES OFFICE Gernsback Publications Inc 500 B Bi County Blvd Farmingdale NY 11735 516 293 3000 President Larry Steckler Vice President Cathy Steckler For Advertising ONLY 516 293 3000 Larry Steckler publisher Arline Fishman advertising director Christina Estrada advertising assistant Shelli Weinman advertising associate Lisa Strassman credit manager SALES OFFICES EAST SOUTHEAST Becky Akers Pattis 3M 310 Madison Ave Suite 1804 New York NY 10017 212 953 2121 MIDWEST PACIFIC Joe Shere 1507 Bonnie Doone Terrace Corona Del Mar 92625 714 760 8697 8861 H38O0100 10 HANDS ON ELECTRONICS eo o TOWER SPEAKERS Continued from page 46 foam or felt damping material in the recess between the tweeter frame and the 4 inch plywood faceplate LE S au y m _ EE Here are the two enclosures with the speaker board removed from one to show its internal construction The board clamped
87. 10 VOLTAGE REGULATORS 7805 7808 78127 7815 79051 7908 7912 7915T 7805K SOLDER STATION a ADJUSTABLE HEAT SETTING WITH TIP TEMPERATURE READOUT a REPLACEMENT TIPS AVAILABLE 2 95 49 95 LAMINATE WITH Gt IEENED LEGENDS 35v 35 35v 35 49 49 49 49 59 69 59 59 1 59 7812 7905K 7912K 78405 78412 79105 79112 LM 323K LM338K 50v 001 50v 005 50v 01 50v 05 50v 1 50V 1 MONOLITHIC 50v 14 50v 50V 15 50V ELECTROLYTIC RADIAL AXIA 1 25v 14 sov 47 50 11 50 16 10 50v 11 16V 14 47 35 13 SOv 19 100 16 15 35v 19 220 35v 20 50V 29 470 25 30 16 29 2200 16V 70 16v 70 4700 25v145 16V 1 25 50v 50V 50v 50v 12V 50v FOR 6 2 32 BIT PROTOTYPE CARD 16 BIT CARD WITH VO DECODING LAYOUT PARTS KIT FOR JDR PR16 ABOVE 16 BIT CARD FOR VIDEO APPLICATIONS FOR AT 16 BIT CARD WITH DECODING LAYOUT PARTS KIT FOR JDR PR1O ABOVE FOR XT WITH 5 AND GROUND PLANE AS ABOVE WITH O DECODING LAYOUT DISCRETE 1N751 15 4328 1 414825 71 4 33 89 1 400410 19 4N37 119 1 5402 25 MCT 2 59 K8P02 55 MCT 6 129 2N2222 25 Tu 111 99 PN2222 10 2N 3906 10 2N2907 25 2N4401 25 2N 3055 79 2N4402 25 2N3904 10 2N4403 25 4N26 69 2 6045 175 4 27 69 TIP31 a9 JDR PR32 JOR PR16 JDR PR16PK JDR PR16vV 47 JDR PR10 JDR PR10PK IBM PR1 1BM PR2 RESISTOR NETWORKS SIP 10 PIN 9 RESISTOR SIP B PIN 7 RESISTOR 16 PIN B RESISTOR DIP 16 PIN 15 RESISTOR DIP 1
88. 176 23 272 3 39 384 ja 50 5 28 6 63 4 22 445 480 17 30 95 13 29 49 71 69 6 25 72 00 750 1850 tensity Capacity Cm NO 9 8 000 8 000 9 600 SOLDER HEADER RIGHT ANGLE SOLDER HEADER WIREWRAP HEADER RIGHT ANGLE WIREWRAP HEADER RIBBON HEADER SOCKET RIBBON HEADER RIBBON EDGE CARD 10 GREY RIBBON CABLE vor iN Model Timer PE 140 1407 VES 9 PE240T YES 12 MIN RS8 232 BREAKOUT BOX C UBLESHOOTING L COMMUNICATIONS OPEN CLOSE INDIVIDUAL CIRCUITS s 20 JUMPERS CROSS CONNECT ANY TWO CIRCUITS D SUBMINIATURE CONNECTORS CONTACTS 15 19 25 37 59 69 69 135 69 75 75 139 79 227 75 85 2 49 2 56 3 89 560 427 684 995 199 225 425 7205 2 35 449 7116 125 125 39 39 DESCRIPTION ORDER 50 185 229 ERASES 2 EPROMS IN 10 MINUTES a VERY COMPACT NO DRAWER THIN METAL SHUTTER PREVENTS UV LIGHT FRDM ESCAPING 34 95 MALE FEMALE MALE FEMALE MALE FEMALE MALE FEMALE METAL GREY D8xxP DBxxS DBxxPR DB8xxSR DB uu PW DB uu SWW IDBuxP IDBxxS MHOODxx MOODxx SOLDER CUP RIGHY ANGLE PC SOLDER 10 LEDS SHOW CIRCUIT ACTIVITY GENDER BO 34 95 WIREWRAP IDC RIBBON CABLE HOODS 39 69 ORDERING INSTRUC TIONS N NUMB N MARK NUM ANI MAL MOUNTING HARDWARE 59 GENDER CHANGERS R25 PINE IMINIATURE SOCKETS DIP CONNECTORS CONTACTS GENDER FF GENDER MM GENDER MF GENDER NM GENDER JB FEM
89. 2 and 25 volt sources may be used to check stereo 8 track cassette and auto cassette player motors YELLOW Fig 3 Here is the complete diagram of the voltage motor box with fixed voltages off 12 15 and 25 volts Resistor R4 varies the 0 5 volt source voltage to the desired level The 0 5 volt variable source can be used to test the very low voltage motors found in the average compact disc CD camcorder or portable cassette player Note that you can reverse the polarity of the 0 5 volt source quickly with SI DPDT switch Potentiometer acts as a small variable voltage control The circuit contains a small power transformer with bridge rectification Four separate 3 amp silicon diodes are located the bridge circuit Capacitor filters out the DC ripple from the silicon rectifiers Each voltage source has a separate fixed voltage regulator filter capacitor and voltage dropping resistor The regulators are 1 watt types Etching the Board All parts except the transformer and the front panel com ponents are mounted on a printed circuit board like that shown in Fig 4 Mount the components as shown in Fig 5 After etching has been completed wash off the board and clean it up with steel wool or a pocket knife Inspect the wiring for breaks at the circle tie points and correct any Tin the PC wiring with the soldering iron Often if the copper is not completely clean the solder will not stick
90. 2 offer just the right amount of offset to allow to turn off during the negative portion of the os cillator s output signal Resistor R3 sets the maximum drive current delivered to the base of QI Capacitor C4 functions as speed up capacitor to couple the high frequency content of the drive pulse to the base of QI forcing it to turn on quickly That keeps the efficiency high and QI cool The narrow output pulse developed at the collector of Ql is direct coupled to a high output piezo tweeter SPKRI The output circuit is designed to drive an 8 ohm piezo speaker only So don t blow the circuit by using a standard speaker with a voice coil There is nothing critical about the circuit so it can be built on perfboard or a printed circuit board In either case the use of an IC socket for Ul is recom mended compact unit can be built by mounting the circuit and speaker in a plastic or metal enclosure and obtain ing power from a wall plug in 9 to 12 volt DC power supply When testing the Audible Critter Chaser aim the piezo speaker away from the work area or temporarily con nect a 1000 ohm resistor in series with the speaker and the output Set R8 to about mid position and turn R9 so that its wiper is at the cathode end of D4 That R9 setting produces the narrowest output pulse and the most irritating sound with a minimum of current drain on the power source Power up
91. 20 inches Low resolution is also a limitation GIZMO first used the device with the Cali fornia public relations agency that repre sents Visitel Although the main headline in that day s Los Angeles Times was legi ble it was impossible to read the dateline under the newspaper s logo In general only the paper s largest type sizes were readable on the screen The memory facility adds some varia tion As GIZMO Ss testers discovered sim ple three picture narratives could be put together and transmitted both direc tons Using the SEND POSE control to bring a stored image up on the screen al lows the receiving unit to send those im ages back to the originating Visitel The memory is canceled once the Visitel is turned off Audio Extremities WALKMAN STEREO CASSETTE RECORDER PLAYER WM D3 Manufactured by Sony Corp of America Sony Dr Park Ridge NJ 07656 Price 379 95 Portable Cas sette Corder TM 11 Manufactured by Sony Corp of America Price 39 95 The pocket tape recorder player is a benchmark product of the contemporary electronics era It s undergone significant advances in the little more than a decade since the product was introduced The so lidity and reliability of the old mono hand helds have been displaced in the Walkman era by sophisticated electronic capabilities in an extraordinarily compact form A consumer can fit a portable recording studio of more than respectable capability into a
92. 4A4LP 12 B19228 HM43256LP 15 3276848 HM43256LP 12 3276808 120ns CMOSMLP HM43256LP 10 3276848 100nsi CMOSMHLP DYNAMIC RAMS 1638441 25005 16384x1 200ns 1638441 150 16384x1 120ns 3276 8 1 200n5s 65536x1 150ns 655 36x41 120ns 65536x1 200ns 6553641 150ns 655361 150nmsHPIN 1 REFRESH 1638424 150ns PIN RRANGEMENT 4116 250 4116 200 4116 150 4116 120 MK 4332 4164 150 4164 120 MCM6665 TMS4164 4164 REFRESH TMS4416 8000 8031 8035 1 49 8039 1 95 8052 BASK 34 95 BOBO 8085 3 95 41128 150 TMS4464 15 41256 150 41256 120 41256 100 131072x1 65536x4 26214441 262144x1 26214441 150n5 1150 lt 1350ns 120ns 100 8086 BOBB 8088 2 8155 8155 2 741574 740575 741576 744583 7415173 49 7445174 39 7415175 39 7415191 49 7415393 7415541 7415624 7415640 8741 8748 8749 8755 741585 741586 74590 741592 7415192 69 7415193 69 7415 194 59 7415 195 69 7415645 7415670 7415682 7415688 5 1258 100 26214481 1 MB 120 1048576x1 1 MB 100 104857641 100ns CMOS 120ns 100ns 0 2 2 amp 3 20 2 40 2708 2716 2716 1 TMS2532 2732 2732A 2732A 2 27C64 2764 2764 250 2764 200 EPROMS 102448 204848 204848 409648 409648 409628 409648 8192 8 819218 819248 8192x8 450 5 25 450ns 25V 35OnsH 25V 450ns 25V 450ns 25V 250ns 21v 200ns i21Vv 250nsj 12 5v CMOS 450ns 12 5V 250nsy
93. 50 NS16450 10 738635 12 0 14 31818 16 0 18 0 18 432 20 0 22 1184 24 0 32 0 CL MUSIHIGH SPEED CMOS 19 4066 4069 25 4070 35 4081 CLOCK CIRCUITS MM58167 9 95 MM58174 9 95 MSM5832 2 95 74HC154 74HC157 74HC244 74 245 74HC273 74HC373 74HC374 74HCTOO 74HCTO2 74HCTO4 74HCTOB 74HCT32 74HCT74 74HCT138 74HCT139 7aHCT161 74HCT240 74HCT244 J4HCT245 74HCT273 74HCT373 7 374 74HCT393 74 4017 1 72 4040 74HCT4060 4093 14411 14433 14 95 14497 6 95 4503 49 4511 69 4518 85 4528 4538 4702 7 74HCO2 74HCO4 74HCOB 74HC10 74aHC14 74HC32 74HC74 74HC86 74HC138 74HC139 74HC151 9 95 MISC AOCOBO4 0809 DACOB800 OACOBOB 1022 MC1408L8 1 95 8728 1 29 8797 59 OP8304 2 29 9334 1 75 9368 2 85 9602 69 ULN 2003 79 MAX232 7 95 MC3470 1 95 MC3487 2 95 AY5 3600 PRO 11 95 BIT RATE GENERATORS 14411 9 95 BR 1941 4 95 4702 9 95 COMB116 8 95 2 99 3 85 3 29 1 95 5 95 INTERSIL 1 7106 9 95 7107 10 95 1CL7660 1 99 1 8038 3 85 7207 5 95 7208 15 95 t t 1 49 JDA Microdevices and the JDR Microdevices are registered trademarks JDR Microdevices PS 2 are trademarks of International Business Machines CIRCLE 18 ON FREE INFORMATION CARD CAPACITORS TANTALUM 15 12 10 15v 42 22 15v 45 47 15v 99
94. 50 allows the portable copier to duplicate halftones reduce or enlarge the original image produce reversed copies transforming black to white or vice versa adjust copy density and enlarge or reduce specific sections of the original material A second add on the facsimile interface enables the 50 to function as a facsimile transceiver Price To be announced CIRCLE 67 ON FREE INFORMATION CARD Panasonic Scientific Calculator We don t know if the computer and the calculator have done away with chalk and blackboard in laboratories in this country but a new Scientific Calculator JE 554U from the Panasonic Co One Panasonic Secaucus NJ 07094 sounds as if it should The hand held unit is equipped with a ten digit LCD readout and performs 166 statistical mathematical scientific and computer functions The calculator also incorporates a 128 step programming mode eight metric conversion functions and presumably for the absent minded scientist an automatic power off feature Price 39 95 CIRCLE 68 ON FREE INFORMATION CARD Citizen Hand Held LCD TV Citizen was a pioneering brand in the mini TV market but dropped by the wayside Now CBM America Corp 2999 Overland Ave Los Angeles CA 90064 is returning to the field with a new Hand Held LCD TV TC 53 05 The set weighing less than one pound offers a built in backlight a 23 inch extending antenna a 2 5 inch diagonal screen and front mounted tuning for VHF UH
95. ALE MALE MALE MALE MALE FEMALE NULL MODEM JUMPER BOX 7 95 7 95 7 95 8 95 8 95 JOYSTICK SET AXIS FOR AUTO CENTER OA FREE MOVEMENT FIRE BUTTON FOR USE WITH GAME SOFTWARE ADAPTOR CABLE FOR APPLE 1 14 45 Terms Minimum order 10 00 For shipping and handling include 2 50 for UPS ground and 3 50 UPS air Orders over Ib and foregn orders may require additional shipping charges piease Contaci the sales depariment for the amount CA residents must include applicable sales tax Prices are subject to change without nonce We not responsible for lypographical errors We reserve the night to limit quantities and to substitute manufacturer All merchandise subject to peior sale A full copy of our term is availabie upon request piciured may only be representative 600 538 5000 CONTINENTAL U S AND CANADA DESCRIPTION SOLDERTAIL SOCKETS WIREWRAP SOCKETS ZIF SOCKETS TOOLED SOCKETS TOOLED ww SOCKETS COMPONENT CARRIERS ORDER BY s 34 16 128 j20 22 24 28 40 xxST 117 10117 12 15 18 15 20 22 xx WW 59 69 69 99 109 139 149 169 199 ZF 495 495 695 595 695 995 AUGAT xST 62 79 89 109 129 139 149 169 249 AUGATxxWW 1 30 180 210 240 250 290 315 370 540 49 59 69 99 99 99 99 109 149 IDPxx 5 49 59 129 149 85 149 159 N MINIA NN A V GENDER MT 5 14 95 EP 9 c 7c rete JOR MICRODEVICES
96. Caulk only on the inside of the cabinet for 121 4 28 Er UNIT ONLY DIA PARTITION BOTTOM SIDE PANEL 38 1 2 best appearance The caulking is required because it is abso lutely essential to have no air leaks or the reflex system will not perform according to plan Next install the speaker panel with glue and nails Again when the glue is set caulk the joints around the edge of the panel Prepare the back by drilling it for air tight speaker terminals The L Pad You can install the L pad in the upper back if you wish but that complicates the wiring a bit t is much simpler to put the L pad on a small board as part of the crossover network at the bottom of the tower Once it is set it is unlikely you will ever change the tweeter level unless you move the speakers to a different listening environment Since you will put all the crossover components in the base you ll need to run wire such as lamp cord up the back to separate terminals for the woofer and tweeter Drill holes for the terminal lugs and solder about 18 inches of inner box cable to the lugs before you glue down the terminal strip on the back Caulk the holes on the inside of the back with silicone rubber If you prefer you can simply run the speaker cables through small holes in the back and caulk the holes E 35 32 1 2 C 10 o 2 O Q i O 0 zZ 2 P
97. D STATE RELAY ELECTROL 4S2161 CONTROL 5 5 10 Vdc will operate 3 32Vdc LOAD 10 Amp 240 Vac CAT SSRLY 10B 9 50 each 10 for 85 00 25 tor 175 00 50 tor 300 00 100 tor 500 00 MAIL ORDERS TO ALL ELECTRONICS P O BOX 567 TwX 5101010163 ALL ELECTRONIC OUTSIDE THE U S A SEND 1 50 POSTAGE FOR A CATALOG concepts behind Word s features and rein forces the concepts with do it yourself ex amples Each chapter is divided into les sons that are illustrated with screen photos and ends with review exercises The 405 page book gives a complete over view of Word s editing features and for matting commands discusses general top Tics such as printing merging and various options and shows how to use advanced features outlines tables of contents spell ing correction indexes and sorting to pre pare business documents The new features in version 4 such as macros and advanced document retrieval are covered Also in cluded are special features for legal docu ments desktop publishing projects text out lining and windows For beginners the book teaches basic word processing terms and describes in de tail how to get started The lessons build on material presented earlier in the text mak ing it easy to advance Readers with some Word experience will find topics mentioned briefly in the Microsoft Word manual elabo rated upon in this book Advanced users will appreciate reference material th
98. Date State of the Art 10 MHz Recurrent with XYZ Axis Under 310 00 RES 5 Resistance Decade Substitution Box 999 999 OHMS in 6 Seg ments in 1 OHM steps Tolerance of Resistors 2 Under 67 00 Available At Your Local Distributor Catalog House Or School Supply Company We Also Have Digital Multimeters Dual Trace Scopes Analog Multimeters Sine amp Square Wave Generators Resistance Sub amp Decade Box EMCO ELECTRONICS P O Box 327 Plainview N Y 11803 Free Catalog CIRCLE 20 ON FREE INFORMATION CARD State ol the Kits by Hal Tronix Inc VARIOUS CLOCK KITS HAL 5314 Most Famous Clock Kit 12 95 6 DIGIT ELECTRONIC CLOCK KIT 12 OR 24 HOUR FORMAT COMPLETE KIT LESS POWER SUPPLY ADAPTOR AND CASE HUNS OFF ANY 12 VOLT AC SOURCE REQUIRES 250 MA HAL 5375 Alarm Clock Kit 16 95 6 DIGIT ELECTRONIC CLOCK 12 OUR FORMAT ONLY OPERATE ON 12VOLTS AC ORDC HAS TIME BASE ONBOARD COMES COMPLETE LESS POWER ADAPTOR AND CASE HAL 79 Student Class Kit 7 95 4 DIGIT BASIC ELECTRONIC KIT WITH OPTIONS AND PROVISIONS TO MAKE IT AN ALARM CLOCK AND A DC OPERATED CLOCK COMPLETE LESS OPTIONS POWER SUPPLY ADAPTOR AND CASE OPTION 1 TO MAKE IT AN ALARM CLOCK 295 OPTION 2 TO MAKE IT A D C 12V CLOCK 4 95 CLOCK CASE Reg 6 50 Clock Case When Bought with Clock Kit ONLY 4 50 12 VOLT A C ADAPTOR Reg 4 95 When Bought with Clock Kit ONLY 2 95 Complete 4 95 CRYSTAL TIME BASE KIT USING MM5369 HAL
99. E amp O VIDEO 9691 E 265th Street Elko MN 55020 1 800 638 6898 SCIENTIFIC Atlanta model 8510 converters with remote 55 without remote 45 ROCK TRONICS P O Box 3113 St Joseph MO 64503 No checks CABLE descrambler liquidation Major makes and models available Industry pricing Example Hamlin combos 44 each minimum 10 orders Dealers only Call WEST COAST ELEC TRONICS 818 989 0890 CABLE TV converter descramblers Original Fac tory Equipment Zenith TOCOM Scientific Atlan ta Oak Jerrold Panasonic Remotes Video Accessories Best buys warranties quantity dis counts Free catalog ARIZONA VIDEO 7739 E Broadway 108 Tuscon Arizona 85710 602 323 3330 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 PLANS KITS BUILD this five digit panel meter and square wave generator including an ohms capacitance and fre quency meter Detailed instructions 2 50 BAG NALL ELECTRONICS 179 May Fairfield CT 06430 VOICE disguisers FM bugs Telephone transmit ters Phone snoops More Catalog 1 00 refunda ble XANDI ELECTRONICS Box 25647 327 Tempe AZ 85282 PC boards made to order Details SASE Eprom programmer plans 3 50 includes semiconductor bonus
100. F stations There s also a flip out stand a hood for cutting glare and reflection and a three way power system which includes portable use with four batteries for up to four hours of continuous mini TV viewing Price 299 95 CIRCLE 69 ON FREE INFORMATION CARD Onkyo Universal Remote Control Among the first brands out of the starting gate with a universal remote control for audio video equipment was Onkyo 200 Williams Dr Ramsey NJ 07446 Now the firm has introduced an update the Universal Programmable Remore Control Featuring 55 separate functions the unit can control over six different components Price 80 CIRCLE 70 ON FREE INFORMATION CARD Code A Phone Tapeless Answering Device We get nervous when companies talk about the ultimate product but Code A Phone 16261 S E 130th Clackamas OR 97015 has put that label on its new All Digital Telephone Answering System 6200 The unit uses integrated circuits to record both outgoing and incoming messages and offers such sophisticated features as selective message save erase an instant message finder and the smart message counter which distinguishes between internal messages left by members of the household or work mates and incoming calls There are also 17 beeperless remote functions toll saver and announcement breakthrough Intro duced at the summer Consumer Electronics Show the 6200 should remain the ultimate digital answering device
101. GALLIUM JUNCTION 540 C N E North gate Way Suite 542 Seattle WA 98125 CATALOG hobby broadcasting HAM CB Cable transmitters amplifiers bugging devices com puters more PANAXIS Box 130 10 Paradise CA 95967 CRYSTAL radio sets plans parts kits Catalog 1 00 MIDCO 660 North Dixie Highway Hol lywood FL 33020 HANDS ON MARKETPLACE PRINTED circuit boards drilled amp etched Free deliv ery K amp F ELECTRONICS INC 33041 Groesbeck Fraser MI 48026 313 294 8720 Plans Kits Education Instruction Wanted Special Category 10 00 16 22 40 17 23 80 21 29 40 22 20 80 26 36 40 27 37 80 31 43 40 32 44 80 Card Number PRINT NAME EXPANDED TY Number 49 on the Free Information Card CLASSIFIED AD ORDER 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 18 25 20 23 32 20 28 39 20 33 46 20 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 nat commercial products or services 1 40 per word prepaid no charge for ZIP code
102. IUS puting from the very start can speak MCD BAT 17 5 14 88 9 57 the wrong computer But just as with 5 2 22 5 14 8 9 56a AP about the problem with some authority MDC BAT 20 5 14 88 9 6a protected software once again it s PRAE A MDEL 18 3 14 88 9 56 202 cus have some excellent protected pro MDIR BAT 2i COPYIIPC to the rescue this time in grams that were sold from someone s Eo 221 the form of the COPYHPC Deluxe Op kitchen table As a general rule most of ee oe 12 22225680 714275 z a the protected programs came with a MTYPE 16 5 14 88 9 57a eS d N PK COM 9968 3 22 88 6149 backup disk duplicate could be 17 File s 59392 bytes free COPYIIPC Deluxe Option Board The Deluxe Option Board and its purchased at a moderate price if the software allows and defective distribution disk was re turned Unfortunately when backup disk was needed the source was long gone Either the programmer had made so much money that he had retired which is What happened in the case of the best ever spelling checker or he was bought out by a larger distributor and all traces of the original source had vanished Alter several years of enduring the vanishing distributor problem with software for Radio Shack s Models 1 2 and 4 computers avoided the problem when the PC
103. It is made of weather repellent pack cloth and has padded removable inserts and accessory pockets for tapes CDs cables and adaptors The acous tically transparent Travel Bag protects the system from sand and dirt Other accessories include a car adaptor and mounting brackets and clamping arms The RoomMate II speaker system with adaptors and speaker wire costs 279 00 The Power Pack costs 89 95 the Travel Bag retails for 85 95 the car adaptor is 24 95 and the mounting brackets and flexible clamping arms are 19 95 and 39 95 respectively For more information contact Bose Corpo ration The Mountain Framingham 01701 Digital Multimeters C G Soar s 3200 Series of DMMs uses custom designed LSI chips to achieve maximum reliability speed ac curacy and operating ease The user simply connects the leads and selects the proper function and the auto rang ing circuit does the rest Each unit features a 32 segment ana log LCD display a high speed sam pling circuit which is much faster than the LCD numerical display The 3200 count display allows higher resolution than that of conventional 3 4 digit CIRCLE 86 ON FREE INFORMATION CARD The 3200 series DMMs have such features as range hold data hold and an audible continuity diode test An adaptor mode for use with Soar s 9300 Series adaptors allows the user to do AC DC current measurements as well as cap
104. Lusk Blvd San Diego CA 92121 Continued on page 103 bj Employers 74 Willing workers available nw now at as little as your usual cost This is your chance to get help you ve needed but thought you 7 couldn t afford No business too large or too small Call your private industry council or write National Alliance of Business PO Box 7207 Washington D C 20044 A Servos o DIRECT ETCH dry transfers make quality circuit boards fast without formal artwork A new Master Assortment includes over 4000 donuts from 050 to 250 and 118 trace lines from 014 to 125 It also contains all sizes of through hole and surface mount devices including DIP TO DIN D and edge card connectors SO SOL PLCC flatpacks SOT 2 terminal tubular and flat SMD s The Master Assortment has 69 cut apart dry transfer sheets PLANS Yourseli AI Parts Available In Stock AMAZING SCIENTIFIC amp ELECTRONIC PRODUCTS LC7 BURNING CUTTING CO LASER RUB4 PORTABLE LASER RAY PISTOL Ama TCC1 3 SEPARATE TESLA COIL PLANS TO 1 5 a 10G1 ION RAY GUN 1080 GRA1 GRAVITY GENERATOR 10 0 e EML1 ELECTRO MAGNET COIL GUN LAUNCHER amp n KITS e MFT3K FM VOICE TRANSMITTER 3 MI RANGE e e VWPM7K TELEPHONE TRANSMITTER 3 MI RANGE 355 BIC3K 250 00 VOLT 10 14 SPARK TESLA COIL ims LHC2K SIMULATEO MULTICOLOR LASER
105. MINIMUM 15 WO 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 Entire ad in boldface 1 70 per word TINT SCREEN BEHIND ENTIRE AD 1 75 per word TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD 2 05 per word EXPANDED TYPE AD 2 red word prepaid Entire ad in boldface 2 20 per word TINT SCREEN BEHIND ENTIRE E AD 2 30 per word TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD PLUS ALL BOLD FACE AD 2 70 per word DISPLAY ADS 1 x 2W 175 00 2 2V 4 350 00 3 x 2W 525 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 Copy to be in our hands on the 18th of the third month preceding the date of issue de Aug issue copy must be received by May 18th When normal closing date falls on Saturday unday or Holiday issue closes on preceding work day Send for the classified brochure Circle 007 type electronics Super surveillance Amaz ing prices Catalog 2 00 JD s ELECTRONICS Dept Box 9042 Wichita KS 67277 PLEASE INDICATE in
106. NTSC RF MOD 19 95 BUILD YOUR OWN VIDEO RF MODULATCR A MINI T V TRANSMITTER FOR CHANNELS 3OR 4 USING AS A OUTPUT FII TER KEEPING CO CHANNEL INTERFER ENCE AT A MINIMUM COMES COMPLETE LESS CASE POWER SUPPLY AND HARDWARE NOTE CASE POWER SUPPLY AND HARDWARE ENCLOSE 512 95 Extra HAL FG 100 69 95 FUNCTION GENERATOR KIT 1 HZ 100 KHZ IN FIVE BANDS AMPLITUDE AND OFFSET ADJUSTABLE OUT PUT IMP 500 OHMS WAVE FORMS SINE SQUARE AND TRIANGULAR AND TTL CLOCKOTOSV LEVEL 200 NS RISE AND FALL TIME COMPLETE WITH CASE AND POWER SUPPL Y AND ALL ELECTRNIC PARTS INCLUD ING MANUAL SHIPPING INFORMATION PLEASE INCLUDE 10 OF ORDER FOR SHIPPING AND HANDLING CHARGES MINIMUM 2 50 MAXIMUM 10 CANADIAN ORDERS ADD 7 50 IN US FUNDS MICHIGAN RESIDENTS ADD 4 SALES TAX FOR FREE FLYER SEND 22 STAMP OR SASE HAL TRONIX INC 9 e 12671 Dix Toledo Hwy 1101 e Southgate MI 48195 Fu 313 281 7773 Hours 12 00 6 00 EST Mon Sat sul CIRCLE 21 ON FREE INFORMATION CARD NOW DEALER FOR TEN TEC AND 886 H38O100 Mo HANDS ON ELECTRONICS L IMAGINE THAT BIG THREE DAY weekend has finally arrived and you ve labored long and hard to get things in tip top shape for the events to come The debris that has cluttered the back yard for all too long has been neatly packaged the night before and set out for pick up by the sanitation depart ment Ah all
107. ONE FREE CATALOG ONLY O Electronic Music Technology C Computers and Microprocessors TV Video Audio Servicing vin Basic Electronics Plea Prmti Age State Zip NRI ts accredited by the Accrediting Commission of the National Home Study Councd 18 108 886 Hd8OLOO HANDS ON ELECTRONICS NEW PRODUCTS The Excursion 50075 battery pack is consumer replaceable It also has a re placeable antenna turther reducing the need for manufacturer service or re pairs The new antenna screws on for simple installation CIRCLE 42 ON FREE INFORMATION CARD The ash tone cordless phone is desk or wall mountable It is compact 9 5 inches and the handset weighs only 6 ounces The Excursion 500 complete with line cord and instruction book has suggested list price of 79 00 For fur ther information contact Northwestern Bell Phones 9394 West Dodge Road Suite 100 Omaha NE 68114 Solderless Breadboarding Labs JM Electronic Products Division s self contained solderless breadboard ing labs are now available with remova ble circuit board assemblies That design allows engineers and technicians to perform multiple circuit projects one per board using a single Powerace Plus Board n classroom use the removable circuit board feature permits students to keep their individu al projects on their own boards The Powerace Models 202 and 203 each come wit
108. OPTOELECTRONICS 5 50 Includes intra red detec ea rid tors transmitters modulated light Iransmission and photographic applications BP179 ELECTRONIC CIRCUITS FOR THE COMPUTER CONTROL OF 1 BP48 ELECTRONIC PROJECTS FOR BEGINNERS 5 50 A wide range of ROBOTS 7 50 Data and circuits for intericing the computer to the robot s easily completed projects for the beginner Includes some no soldering projects motors and sensors BP126 BASIC amp PASCAL IN PARALLEL 4 95 Takes these two program Ee ee 5 95 Radio audio household ming languages and develops programs in both languages simultaneously anc test equipment projects are all included C PCP104A ELECTRONICS BUILD AND LEARN 9 95 starts off with construction details of a circuit demonstrator and shows a variety of circuits for experimenters 1 BP198 AN INTRODUCTION TO ANTENNA THEORY 6 95 Basic concepts relevant to receiving and transmitting antennas 1 225 A PRACTICAL INTRODUCTION TO DIGITAL 1C S 5 25 Mainly con cerned with TTL devices Includes several simple projects plus a logic circuit test C BPS6 ELECTRONIC SECURITY DEVICES 5 50 Includes both simple and Set and a digital counter timer more sophisticated burglar alarm circurts using light infra red and ultrasonics 1 BP170 INTRODUCTION TO COMPUTER PERIPHERALS 5 95 Shows how 59 BOOK CMOS IC PROJECTS 5
109. P234 TRANSISTOR SELECTOR GUIDE 10 00 Companion volume to CORTOS pM 235 Book covers more than 1400 JEDEC JIS and brand specific devices Also contains listing by case type and electronic parameters Includes Darlington LED CIRCUITS selection of simple applications transistors high voltage devices high current devices high power devices iS simple electronic component BP99 MINI MATRIX BOARD PROVJECTS 5 50 are 20 usetul circuits BP127 HOW TO DESIGN ELECTRONIC PROJECTS 5 75 Helps the reader that can be built on a mini matrix board that is just 24 holes by ten copper foil strips to put projects together from standard circuit blocks with a minimum of tnal and error 1 BP157 HOW TO WRITE ZX SPECTRUM AND SPECTRUM GAMES PRO GRAMS 4 95 A crystal clear step by step guide to writing your own graphics 1 BP122 AUDIO AMPLIFIER CONSTRUCTION 5 75 Construction details lor games programs preamps and power amplifiers up through a 100 watt DC coupled FED amplifier 1 BP117 PRACTICAL ELECTRONIC BUILDING BLOCKS Book 1 5 75 Oscillators Timers Noise Generators Rectifiers Comparators Triggers and more C BP184 INTRO 68000 ASSEMBLY LANGUAGE 6 95 The 68000 15 BPS2 CRYSTAL SET CONSTRUCTION 5 50 Everything you need to know about building crystal radio receivers Prog asse BP45 PROJECTS IN
110. Publications Inc 500 B Bi County Boulevard Farm ingdale NY 11735 Second Ciass postage paid at Farmingdale NY and at additional mailing offices One year twelve issues subscrip tion rate U S and possessions 521 95 Canada 26 95 all other countries 529 45 Subscnption orders payable in U S funds only International Postal Money Order or check drawn on a U S bank U S single copy price 52 50 c 1988 by Gernsback Pubiications inc All rights reserved Trademark registered in U S and Canada Printed in U S A Postmaster Please send address changes to Hands On Elec tronics Subscription Dept Box 338 Mount Morris It 61054 9932 A stamped selt addressed envelope must accompany all submitted manuscripts and or artwork or photographs if ther return is desired should they be rejected We disclaim any responsibility for the loss or damage manuscripts and or artwork or photographs while in our possession ot otherwise As service to readers Hands on Electronics publishes available plans or information relating to newsworthy products techniques and scientific and technological developments Because of possi ble vanances in the quality and condition of matenals and work manship used by readers Hands on Electronics disclaims any responsibility for the safe and proper functioning ol reader built projects based upon or from plans or information published in this magazine MERE E AA
111. R 2 33 6 6 V HANDS ON ELECTRONICS Now let s take somewhat more complex circuit Refer to Fig 10A Again we wish to compute the Thevenin s equiv alent voltage and resistance As usual we begin by removing the load resistor See Fig Then we calculate the output voltage between terminals A and B Note that we are using an AC generator That is just to remind you that Thevenin s theorem works for both AC and DC circuits The generator in the circuit supplies 6 volts to the network made up of resistors R2 and R3 Note that and R2 form a voltage divider across the generator Since the two values of resistance are equal then the source voltage will simply divide equally across them That means that there will be 3 volts dropped across and 3 volts dropped across R2 The voltage across R2 is the output voltage applied to terminals A and B The voltage is of course applied through resistor R3 Since there is no load connected to terminals A and B then no current flows through R3 and so there is no voltage across it So the voltage across terminals A and B is simply the voltage across R2 or 3 volts That is the Thevenin s equivalent voltage Vp Next compute the Thevenin s equivalent resistance That is done by shorting the generator and computing the total value of resistance between terminals A and B The equiv alent circuit is shown in Fig 10C First note that RI and R2 are simply p
112. Remove excess copper with a pocket knife Drill out the component mounting holes with a small drill bit Mounting the Parts Mount all small components on the etched board Keep all the hot parts such as the regulators about 7 above the board Be sure to supply U1 and U2 with heat sinks Observe the polarity of the electrolytic capacitors and the IC regulators Remember the positive terminals of silicon diodes D2 and D4 connect to the positive terminal of the large filter capacitor Solder each connection with a low wattage soldering iron When done double check each part for correct mounting and polarity After the PC board wiring is complete drill two 6 32 holes to mount Make the holes to the right side of the plastic project box They may be drilled or made with the small tip of the soldering iron Bolt the transformer in place Solder the secondary s 18 volt leads to the PC board solder pads marked 25 J2 15V J3 12V e COM J5 0 5v Mee Je J7 MONITOR JACKS J8 8861 H38O100 m HANDS ON ELECTRONICS o PARTS LIST FOR THE MOTOR VOLTAGE BOX SEMICONDUCTORS U1 7815 15 volt regulator integrated circuit U2 7812 12 volt regulator integrated circuit U3 7805 5 volt regulator integrated circuit D1 D4 1N5402 3 amp 200 volt silicon diode CAPACITORS C1 2 2200 35WVDC electrolytic 4 01 100WVDC ceram
113. SIC tor the Atari ST which is the machine that I own It will have to be modified to run under other variations of BASIC What the program basically does is take the left character of an input string and convert it to ASCII send the ASCII code to the serial port subtract it from the string repeat the process until all of the string characters have been sent and then send a carriage return have found that sort of program ming most useful for children s educational programs such TABLE 2 DIP SWITCH FUNCTIONS Mode Selection Switch Mode 1 2 3 Off Off Off Off On Off On Off On On On Off On On On Parallel Input Mode Serial Mode 50 Baud Serial Mode 110 Baud Serial Mode 300 Baud Serial Mode 1200 Baud Serial Mode 2400 Baud Serial Mode 4800 Baud Serial Mode 9600 Baud 4 Off Carriage Return Only Delimiter On Any Delimiter Ee Inside the author s prototype The author used a card edge connector mounted on a home made right angle bracket to secure one side of the board the other is mounted on non conductive stand offs While the card edge connector allows easy wiring to the off board components many other mounting schemes are also acceptable and should work just as well LISTING 1 Start Program marker Input A Input a phrase Do The beginning of a loop C Len A C the length of A if C 0 Then If AS has all been sent then Out 1 13 Send
114. Supply Voltage 3 0 to 15V Vin Input er 0 to Voo Operati emperature Range 04014 55 125 CD4014BC 40 to 85 on KS LEVEL CHANGE NO CHARGE X DON T CARE CASE STATIC ELECTRICAL CHARACTERISTICS Output High Source Current Input Current lin RETRIGGERABLE ONE SHOT y 1 1 TIMING DIAGRAMS 2200pF INPUT 2 1 NORMAL RETRIGGERABLE OPERATION CONDITIONS LIMITS at 25 Typ Sink Current 05 1010 10 26 Min 15 015 15 68 Output High 4 amp 8 o5 5 1 Source Current lon Min COSE Input Current ORE Output Voltage Low Level Vo Output Voltage High Level Min Input Low Voltage Vi Max Input High Voltage Vi Min T 118 C CHOOSE R ANO C FOR PULSE WIDTH GREATER THAN ANTICIPATEO CONTACT TIME Output Voltage Low Level Output Voltage High Level Min Input Low Voltage Input High Voltage Ving Min 4 a a A e we ew oe mo ee ee gt During the next 12 months Radio Electronics will Carry up to the minute articles on hobby computers solid st
115. T2 The field causes a current to be induced in the secondary winding of T2 The secondary output of T is fed across three SOO pF 10 kilovolt doorknob capacitors collectively designated C5 that are parallel connected and tied across the high voltage output of T2 as an energy storage device Those capacitors charge up to TI s secondary voltage and are then discharged through the spark gap and the primary L1 of the Tesla coil producing higher voltage in the secondary of the coil L2 The secret of producing a successful Tesla coil is in the tuning of the primary coil to the natural resonance frequency of the secondary coil Because variable 10 kilovolt capacitors are about as common as Condor eggs some other means must be used to tune L1 The simplest method is to tap the primary coil on every turn and select the tap that produces the greatest voltage at the hot end of L2 Perfboard Assembly The author s prototype was built breadboard style on an 11 X 11 X l inch wooden cutting board see photos but any similar non conducting material perhaps plastic will do The majority of the small components as shown in the photos were mounted on a 3 X 5 inch section of perfboard and point to point wiring techniques were used to complete the connections Refer to the schematic diagram in Fig 2 and the photos for wiring and general parts layout details Note Components TI and T2 C5 and Q4 F1 and SI are not mounted to the perfboa
116. This order subject to acceptance by the Electronics Book Ciub RESP 1088 SELECT BOOKS Ez for only 3 95 and get a Free Gift 222 2912 523 85 1897P 513 95 ELECTR NK S FIX IT Haw le head Electranic 2883 25 95 a 1599 17 95 222731 21 95 ELEC TRONIC CONVERSIONS Symbois and Formulas Rufus Turner and Aen Gibileco 728P 11 95 j ELECTRIAICS d PROJECTS eo T m 2 5 2941 521 85 1421 516 50 w 8861 H3d8O100 HANDS ON ELECTRONICS Hands on Electronics 500B Bi County Boulevard Farmingdale New York 11735 D No Dogs Allowed Do you have a circuit for an ultra sonic emission dog repeller I m inter ested inthe frequencies and components used In particular need a suitable speaker with enough power at those frequencies VW P Wichita KS What a timely question See this month s Circuit Circus for some cir cuus that might be just what vou are looking for Tuned Out I live in the hills of Southern Cali fornia where the terrain is good for de terring smog but terrible for FM radio signals bought a signal enhancer but wasn t pleased with its performance The main problem was that it couldn t be tuned It would enhance a strong signal if was slightly off frequency but it wouldn
117. Winding the Primary Coil The primary coil L1 is wound on a form cut from a 4 inch diameter plastic sewer pipe to a length of five inches see Fig 5 Take a 27 foot piece of 12 insulated solid copper wire and strip away s inch section of insulation at about every 12 inches continuing for one half the length of the wire 12 times total Those stripped areas serve as tap points for tuning the coil TURN 25 25 TURNS NO 12 SOLIO COPPER WITH TAP PLASTIC INSULATION ON 13 ANO 5 ALL TURNS ABOVE COIL FORM 4 INCH OIAMETER PLASTIC SEWER PIPE ALL OIMENSIONS IN INCHES Fig 5 The form on which L1 is wound is a five inch length of four inch diameter plastic sewer pipe A 27 foot length of 12 insulated solid copper wire with 12 quarter inch sections of insulation stripped away at intervals of about every 12 inches is then wound onto the form Wind the coil starting at the top of the coil form see Fig 5 with the end that has the 12 tap points n other words turn 25 is the first winding to be made That gives a tap on every turn from turn number 13 to turn number 25 Drill two small holes in the coil form where the winding starts and ends Those holes are used to secure the ends of the windings see photos Winding the Secondary Coil The secondary coil form see Fig 6 is cut from a section of 1 diameter plastic water pipe which actually mea sures 4 inches in diameter So when selecting your second
118. a series of measurements and calculations though we can determine the output impedance value To do that use the following procedure 1 Measure the open circuit generator voltage With no load on the circuit connect a multimeter or oscilloscope across the generator output terminals A and B Measure the output voltage That is the real generator source voltage as no current is flowing through the internal resistance R Assume you measure 6 volts 2 Next connect a load R to generator terminals A and B In general it is best to connect a load resistance that is close to but somewhat higher than the internal impedance Since you don t know what the internal impedance is it is difficult to estimate what kind of load resistance to connect Although in some cases you may have a feel for the general range of the output impedance If you do then assume a load resistance that is somewhat higher In that case let s just say that you guessed the output impedance is about 50 ohms but you don t really know for sure Say you picked a 100 ohm load resistance J With the load connected measure the load voltage Let s say you measured 4 volts 4 You now have enough information to calculate the circuit current You can determine the current with law by simply dividing the load voltage by the load resistance l V R 4 100 04A 5 Now you are ready to actually calculate the internal generator impedance You do that with a combinat
119. a Simple dipole through helical de Signs to a multi band um brella 5 Es BP136 25 INDOOR KEW EM Bo eem o and deliver great o MAIL TO Electronic Technology Today Inc 11762 0240 SHIPPING CHARGES IN USA AND CANADA 0 01 to 5 00 1 25 30 01 to 40 00 5 00 5 01 to 10 00 52 00 40 01 to 50 00 6 00 10 01 to 20 00 3 00 550 01 and above 7 50 20 01 to 30 00 54 00 SORRY No orders accepted outside of USA and Canada Total price of merchandise Shipping see chart Subtotal 22222 Sales NYS Total 5 City State Zip EE Tsi l j ue i LN 4 W Handyman s Handbook l m a new subscriber to Hands on Electronics and find it quite interest ing For several years now lve been doing repair work for friends and rela tives When transistors came on the scene I took some courses and learned how to service solid state equipment also Now have people asking me about repairing automobile radios and tape play ers with digitally synthesized PLL all electronic tuning l ve also had requests about cordless phone repairs Many re pair shops tell people that the c
120. acitance temperature and tran sistor testing 2500 hour battery life is expected with alkaline cells The Model 3210 costs 75 00 Model 3220 costs 99 00 and Model 3230 costs 132 00 Further informa tion is available from Soar Sales Department 434 Windsor Park Drive Dayton OH 45459 Tel 513 434 6952 Multifunction A D I O Card R7 4 card for PCs XTs ATs and compatible computers offers l6 analog inputs and 2 analog outputs of 14 bits resolution each That multifunc card also has 16 digital inputs and 16 digital outputs and a 3 channel programmable interval timer counter CIRCLE 87 ON FREE INFORMATION CARD Menu driven easy to use soft ware featuring continuous data re cording to disk display and print functions start and stop time set scan and linearization equations for ther mocouples also comes with the 714 card The R714 including user manual with sample programs is available for 995 00 trom Rapid Systems 433 North 34th Street Seattle WA 98103 Tel 206 547 8311 Surge Suppressor Like light bulbs surge suppressors eventually burn out leaving electronic equipment unprotected with no warn ing The Dragon surge suppressor of fers worry free protection by immedi ately sounding an alarm when it has blown To restore its power the user plugs in a quick replacement module similar to replacing a blown fuse In stead of replacing the entire str
121. ada Total price of merchandise Shipping see chart Subtotal Sales Tax NYS only Total Enclosed Name Address City State Zip Electronics Library howto prepare the Word program use other programs with Word and alter printer driv ers and present the answers to the review exercises Microsoft Word Made Easy Third Edi tion costs 18 95 and is available from Osborne McGraw Hill 2600 Tenth Street Berkeley CA 94710 CIRCLE 96 ON FREE INFORMATION CARD EXPERT SYSTEMS AND ARTIFICIAL INTELLI GENCE APPLICATIONS AND MANAGEMENT Edited by Thomas C Bartee This 304 page book is a collection of es says written by leading authorities in Artifi cial Intelligence Al It highlights the appli cations of Al in finance communications space and military systems Aimed at the professional level business person analyst or computer scientist working with expert systems or other disciplines the book thoroughly explains problem Solving knowl edge representation and natural language processing Expert Systems and Artificial Intelligence Applications and Management presents an overview of the basic principles of Al ex amines current applications in several fields and discusses ongoing research and future applications The book also presents valu able insights into the history and develop ment of artificial intelligence Priced at 39 95 in h
122. after No Risk Guarantee If not satisfied with your books return them within 10 days without obligation Exceptional Quality All books are quality publishers editions especially selected by our Editorial Board All books hardcover unless numbers are followed by a P for paperback Publishers Prices Shown 1988 ELECTRONICS BOOK CLUB Blue Ridge Summi PA 17294 0810 FREE when you join Here s 15 Best IX Iton d Horns All Time Favorite Electronic Projects EcecTRomicsBoow Ciuue Blue Ridge Summit PA 17294 0810 Please accept my membership in the Electronics Book Club and send the 5 volumes listed below plus my FREE copy of Delton T Horn s All Time Favorite Electronic Projects 3105P billing me 3 95 plus shipping and handling charges If not satistied may return the books within ten days without obligation and have my membership canceled agree to purchase at least 3 books at regular Club prices plus shipping and handling during the next 12 months and may resign any time thereafter Electronic Projects From Delton T Horn a 7 95 Projects you can build some i unique some old favorites from value the author s vast treasury of elec tronics know how io Name Address City State Zip 0 _ Phone Signature I RAE Valid for new members only Foreign applicants will receive special ordering instructions Canada must remit in U S currency
123. all channels memory scan for the 30 memory nels and an all weather channel scan With mounting bracket and water re sistant microphone the TKM 407 has suggested retail price of 599 99 An optional flush mount kit is also avail able Further information can be ob tained from Kenwood U S A Corpora tion Communications amp Test Equip ment Group 2201 E Dominguez St Long Beach CA 90810 Tel 213 639 4200 Compact AC Line Voltage Monitor DI Products AC line voltage monitor Model APM43 15 used to de termine the status of 110 VAC and 220 VAC line voltages A single calibrated dial face uses colored bands to highlight the 100 120 VAC and 210 230 VAC ranges Its full scale voltage reading 15 300 VAC The APM43 has standard two CIRCLE 46 ON FREE INFORMATION CARD prong plug molded into its case allow ing it to be inserted directly into an outlet The monitor can be used s portable hand held meter for rapid test ing of outlet voltages or tor long term line voltage observations Due to its unique case design the APM43 AC line voltage monitor can also be panel mounted Serrations molded on two sides allow quick mounting by pushing it into panel cutout for a press fit The compact meter measures only 1 69 x 1 69 x 2 28 inches The APM43 ts available in quantities of 100 pieces for 14 40 apiece from DI Products Inec 95 East Main St Huntington NY 11743 Dubbing Cassett
124. ally peeling any firm flesh fruit or vegetable neatly and in seconds A medium sized apple for example will be evenly peeled in some 17 seconds wasting little or no inner flesh Stainless steel cutting blades six are included with the unit follow the contours of any fruit or vegetable which in turn will allow the user to prepare shoestring potatoes citrus zests skinless fruit pies and perfect garnishes Price 44 50 CIRCLE 58 ON FREE INFORMATION CARD Nikko Gamma Tuner There may be a passing of an era involved in the new Gamma Tuner G 400 from Nikko Audio Products 5830 S Triangle Dr Commerce CA 90040 It seems Nikko s variable high blend control uses a rheostat that increases apparent sensitivity by squeezing upper trequencies As a result in its upper most position there is virtually no stereo separation of the higher frequencies and at its lowest position stereo separation is maximized Hence goodbye stereo mono switch on the G 400 Which we guess is like when manufacturers stopped including 78 and 16 rpm s on standard turntables Other G 400 futuristic features include ten station preset on the tuner s FM AM bands five second station memory scan muting narrow wide IF selector seek auto tuning and even old fashioned manual tuning The station memory back up is good for up to four days if there s a power outage or the unit is unplugged The Gamma 400 is described as a 19 rack mountabl
125. amp Free Order Line NOW 408 732 1573 800 4 HALTED ers and power supplies Each itemis illustrated with a photograph Specifications are provided as well as a description of each unit Several new items are featured in this catalog Those include a combination digi tal multimeter digital storage scope with com panion printer a synthesized NTSC test Sync signal generator a combination wave form monitor vectorscope an AM FM ste reo signal generator and two battery powered NTSC pattern generators The 1988 Short Form Catalog is free upon request from Leader Instruments Corpora tion 380 Oser Avenue Hauppauge NY 11788 Tel 1 800 645 5104 CIRCLE 56 ON FREE INFORMATION CARD MICROSOFT WORD MADE EASY THIRD EDITION by Paul Hoffman This book which shows new Word users how to handle that powerful word process ing program with skill and confidence has been revised to include all the features of Word version 4 Versions 1 through 3 are also covered Microsoft Word Made Easy explains the SEND FOR 295 495 239 89 95 5 eem TEAC FD 55B DISK DRIVE 89 95 2 1 4 X VAN NUYS ITT series 3 4 X 1 2 gray rectangular key 37 VOLT D C SOLENOID Intermittent duty cycle 240 ohm coil Mounting flange is 1 1 8 wide Solenoid body 11 27 X 1 27 X 1 2 Er CAT SOL 34 1 00 each 10 for 8 50 100 for 75 00 Large Quantity Available 10 AMP SOLI
126. an bent copper wire An Introduction to Antenna Theory cov ers the basic concepts relevant to receiving and transmitting antennas This heavily il lustrated book emphasizesthe mechanisms involved and minimizes the mathematics used The 86 page book begins with a definition of the antenna and general wave motion It discusses electromagnetic waves antenna efficiency resistance to radiation complex impedance reciprocity directionality and parasitic elements It describes severaltypes of antennas including simple transmitting frame helical slot dielectric clad micro wave long wire travelling wave supercon ducting and active antennas An introduction to Antenna Theory or der No BP198 is available for 8 95 from Electronics Technology Today P O Box 240 Massapequa NY 11762 MICROSOFT WORD THE COMPLETE REFERENCE By Eric Alderman ing its displays and menus editing and fin Written for all Microsoft Word users this comprehensive guide contains detailed list ings of all functions and commands The new features of Version 4 revision marks document retrieval line and box drawing paragraph borders remappable function keys and its powerful macro language are included Microsoft Word The Complete Reference is divided into three sections for easy ac cess to information It begins with an intro duction to the Word s basic features includ
127. and remaining times for all popular cassette lengths That feature is par ticularly useful when editing The TA RW 490 has two full y independent real time counters to complement its dual record capability The TA RW490 s computer con trolled synchro dubbing feature matically coordinates both transports when transferring material from one tape to the other The Direct Music Search on both transports skips directly to any song up to l6 ahead or 15 behind the current location The TA RW470 has a suggested retail price of 500 00 the suggested price of the TA RW490 is 630 00 For further information contact Onkyo 200 Williams Drive Ramsey NJ 07446 Glass Mounted Active Antenna The Super Vak Tenna provides short wave listeners and scanner owners with superior performance easy mounting and compact size in one antenna t mounts to glass surfaces by means of two powerful suction cups making it convenient for use in an apartment or while traveling CIRCLE 48 ON FREE INFORMATION CARD A full 15 feet of coax cable is pro vided between the antenna and the power unit to aid in installation The Super Vak Tenna is powered by 110 VAC A temale BNC jack is provided for connection to a receiver The re ceive only antenna continuously covers from 500 kHz to 800 MHz for reception of UHF and VHF as well as MF and HF An internal active amplifier pro vides a minimum 14 dB signal boost The Super Vak Tenna c
128. ansmit photos and half tones as well as printed and written documents lts built in telephone features automatic dialing for up to 87 numbers with a dozen frequently called numbers accessible with single touch dialing It can also be programmed to dial a second number if the first one is busy The UX 160 is compatible with Group 2 and six minute North American FM fac similes and offers turnaround polling which Sharp explains allows net worked facsimiles to exchange information during low rate evening hours Price 2 299 CIRCLE 81 ON FREE INFORMATION CARD OF M Cursor keys have been around since the dawn of computer monitors But what alternatives are there and who makes the best We cover the lot here and separate the mice from the men By Jeff Holtzman NE REASON PC S ARE GREAT IS THAT COMPUTER Q power continues to spiral upward while price goes in the opposite direction Nowhere is that more apparent than in the field of microcomputer graphics For example when the PC was first released in 1981 the CGA was the best and the only graphics adapter money could buy In its high resolution mode it could fit 640 dots on each of 200 lines but only in two colors You could also get four colors in a 320 x 200 pixel mode Nowadays however you can get graphics adapters with resolutions approaching that of engineering workstations 1000 x 800 pixels and even more Of course graphical power is nothing without an
129. ape Once the player and recorder are at tached via the Cut 10 all equipment is Page 4 GIZMO controlled by the editing deck The display keeps the user in touch with what function 1s being performed and the arrangement deletion and duplication of selected scenes There s also a timer and indicators showing which connected unit is active and other time and process re lated data So much so that Hama suggests the home editor keep a separate written list of cuts and the sequences being created with them The instructions include sug gested forms for manual record keeping a surprisingly low tech adaptation to the limits of the human memory Hama hopes to incorporate that function elec tronically in future models of the Cut 10 The LCD numbers are a bit overwhelm ing at first glance There are time related numbers including a stop watch func frame digits the numbers assigned to each of the cut segments and a tew more whose purpose we never did quite nail down The 49 button control panel shares a number of characteristics with a computer keyboard including the all important cancel function allowing the home ed itor to delete mistakes betore they happen Similarly a cursor on the display keeps track of the segment or cut being moved or modified showing the operator its assign ed position in a row of numbers that repre sent tape segments The unit takes a stab at reducing user confusion with interact
130. archival backups of virtually all IBM software essentially anything that doesn t use a protection scheme that involves physical damage to the disk itself n addition if your computer has a 3 5 inch drive or if it can be up graded or expanded with a 3 5 inch drive you ll be able to transfer files from a PC XT AT PS 2 Model 25 or 30 to a Macintosh disk and vice versa existing disk drive cable connection from the motherboard to the Deluxe Option Board and connect the cable from the Option Board to the mother board Dual connectors on the Deluxe Option Board allow the adapter to be used in computers using either card edge or pin connectors Bit Bypass Most disk protection schemes de pend on certain quirks of existing disk Plug in jumpers automatically program the board for PC XT or AT Compaq operation The board and its software give the computer the same kind of disk du plication technology used by many commercial disk duplicators As illus trated in the screen print shown in Fig the software provides the required Macintosh disk commands such as MCOPY MTREE MTYPE etc which are self explanatory because they are similar to the PC DOS commands Simply eliminate the M and you get COPY TREE etc As shown in the photograph the De luxe Option Board which must be jumpered for PC XT or Al Compaq type computers comes with
131. ardcover only Ex pert Systems and Artificial Intelligence Appli cations and Managementis available at com puter stores bookstores electronics dis tributors or directly from the publisher How ard W Sams amp Company 4300 West 62nd St Indianapolis IN 46268 Tel 800 428 SAMS CIRCLE 95 ON FREE INFORMATION CARD IBM PS 2 HANDBOOK by Richard Dalton with Scott Mueller IBM s Personal System 2 5 2 computers are redefining the personal computer mar ket Not Simply another new computer PS 2 is a family of new machines monitors printers and a desktop publishing package The PS 2 Handbook is a comprehen sive guide to each of the new machines and components It details how the new sys tems perform better than previous IBM com puters and explains the various audiences for the different models The book explains how the reader can benefit from the PS 2 It describes the tech nological breakthroughs behind the system including the new system board design MCGA and graphics and Micro Chan nel Architecture and how they work to bring the user unprecedented power For people considering the purchase of a PS 2 IBM PS 2 Handbook describes the innovative features that distinguish each par ticular machine from the low end Model 25 to the high powered Model 80 The book s checklists also help readers determine which machine best suits their needs Readers who
132. ary coil form take a ruler with you and be sure to come home with the correct diameter pipe You ll also need two plastic end caps that snugly fit the ends of the tubing Make a mark on the coil form about one inch from each end That sets the starting and ending points for the winding Fill the space between marks with a neat solenoidal winding of 26 enamel covered copper wire Winding the coil by hand shouldn t take over an hour and if a lathe is handy you should be able to complete the job in about 15 minutes Leave NO 26 SOLIO COPPER WIRE LAST WINOING ALL OIMENSIONS IN INCHES Fig 6 Using 26 enamel coated copper wire L2 is wound on a 24 inch length of 1 inch diameter plastic water pipe either by hand or if available using a lathe about 6 inches of wire at both ends of the winding for making connections Spray several coats of Krylon clear 1301 acrylic on the coil for added insulation and protection against moisture Always let each coat dry completely before applying the next Two or three coats are sufficient Its Coming Together Mount one of the 12 inch plastic end caps to the center of the 9 inch circular deck with a l inch long 8 32 screw washer and nut Take two small metal L brackets and mount the primary coil centered around the end cap on the 9 inch base Drill a small hole through the end cap and base board near the rim of the cap Take the secondary coil and push on
133. as not creat ing new capabilities from scratch While programming procedures or internal moditications can cause the fre quency display of a scanner to show a wide variety of apparently new fre quencies doesn t mean that the scan ner is actually picking up any signals on the frequencies being displayed In fact when you get more than a few hundred KHz past the limits of the manufac turers original design parameters for Irequency coverage the unit simply Isn t going to perform Your best hope would be if you could perhaps program into your scanner the ability to pick up new frequencies within the set s overall frequency coverage For instance if the UHF band on your scanner normally accepts pro gramming in 25 KHz increments you may be able to convince tt to accept frequencies spaced closer together Even so not all scanners will jump through that loop for your pleasure The bottom line is that with the ex ception of the 800 MHz band cellular frequencies scanner manufacturers would be only too happy to offer their customers the ability to scan the widest Irequency range possible within the de sign capabilities of their products If all It took to make the unit substantially more versatile was adding or subtract ing a wire or component from the cir cuit punching up some odd gt amp Modification Data Clamor procedures then they d have thought ot c Ever since we mentioned tha
134. ate technology TV games Video color TV stereo test equipment radio radar detectors e industrial electronics servicing TV radio stereo experimenter circuits exceptional construction projects TOUR 14d Q3 amp Q4 ON ALUMINUM HEAT SJNK MOUNTING STRAP BUS NO 1250110 COPPER WIRE CONNECTS TO L1 GND MAIN GROUNDING POINT Fig 3 The author s prototype was built breadboard style 11 x 11 x 1 inch wooden cutting board and most of the components were mounted on a 3 x 5 inch piece of perfboard Two brass strips about wide by 3 inches long are used to tie the three high voltage capacitors together If doorknob capacitors cannot be located often they can be salvaged from older black and white TV s a substitute can be made from window glass and aluminum foil To fabricate C5 take a 10 inch square piece of glass like that of a picture frame and glue a 9 inch square piece of aluminum foil to the center of the glass on both sides leaving an equal border around each aluminum plate Cut two 6 inch lengths of 22 insulated stranded wire Strip about 3 inches of insulation from one end of each wire and tape the stripped end to each of the aluminum plates Shown here is the 9 inch circular deck supported by four dowel rods and an end cap positioned at its center The Deck Figure 4 and the photos show the top deck of the autho
135. ations card or asynchronous For Commodore 64 and 128 machines there are several devices on the market that plug into the user port at the rear of the computer A multi function interface accessory is necessary for many applications One such unit is MFJ 278 Multi Mode Data Controller offered by MFJ Enter prises Inc PO Box 494 Mississippi State MS 39762 800 647 1800 That unit allows you to operate in seven modes Packet ASCII RTTY BAUDOT RTTY CW WEFAX SSTV and Contest Memory Keyer Books There are only a few books on the market that link computers and amateur radio If you are interested in such liter ature you might want to review Micro computers in Amateur Radio No 1305P which retails at 10 95 and the Packet Radio Handbook No 2722P at 14 95 Both are published by TAB Books Inc PO Box 40 Blue Ridge Summit PA 17214 In addition Howard W Sams amp Co Inc 4300 West 62nd St Indianapolis IN 46268 offers my book Commodore 64 amp 128 Programs for Amateur Radio amp Electronics No 22516 14 95 The book and a diskette containing the programs are available from the author Computers and EMI One of the major drawbacks to inter facing some computers with amateur radio equipment is electromagnetic in terference EMI commonly called crud and a few other more colorful names The clock and digital circuits within the Computer its switching power supply and its
136. ay know the use of electronic device on planes is restricted especially receivers That makes using the jacket on the plane no no in the first place So if vou ve got one pack it or leave it at home Haves and Needs would like to know how to build a voice activated recognition device If any one can help please write to me Timothy Green 2034 Ocee Drive Riverdale GA 30296 l am looking for information on my audio amplifier made by the Great American Sound Co Inc of Chatsworth CA There is no apparent model number on the unit it might sim ply be called Son of Ampzilla have attempted to contact the com pany with no success need a parts list and schematics for that unit or a current address of the manufacturer Thank you Randy E Meyer 715 Park Avenue So Milwaukee WI 53172 am desperately in need of a sche matic for a Teledyne 4 Channel Quad rasonic Radio Receiver Model No RA 632 tried Olson Electronics who sug gested I write to Teledyne Corp who told me to try Cube Master who seems to have disappeared Robert K Browne 9818 McKnight NE Albuquerque NM 98112 CIE MAKES THE WORLD 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 com
137. ayback Module Kit with external circuitry added All the designed features are included in this illustration electrolytic capacitors A careful check of your work before applying power should turn up such errors before any damage is done Begin by mounting and soldering the smaller parts the watt resistors small capacitors and the transistor to avoid damaging the transistor handle its leads carefully and don t force them into place Follow up by mounting and soldering the IC sockets big capaci tors and potentiometers Finish up by installing the terminal pins That s about ninety percent of the job The board should now resemble the one shown in Fig 2 Testing the Circuit Board Hook up the board as detailed in Fig 3 Connect condenser microphone in the following manner nect and solder the tab on the metal Shell to the microphone lead nearest to it and a short length of wire That wire connects to terminal on the printed circuit board The remaining microphone lead with the help of a short wire lead connects to the mic terminal Connect the LED to the printed cir RV1 CLOCK RV2 REC VOLUME CC CC 1 011 220 16 9 27 R14 820K SPRK1 AV3 VOLUME A view of the printed circuit board after all the parts are mounted What you see in this photo are the board and most of the parts that are supplied with the module kit Not show
138. bands shortwave ham AM broad Cast eic we don t havea circuit that s suitable for use in the FM broadcast band in our library Perhaps one of our readers can help with this If vou have a circuit that will do the job send it along we ll publish it in a future issue Old Issues For New Reader The July 1988 issue of Hands on Elec tronics was the first one l ve read In the Letter Box one of the answers referred to previous issue concerning shortwave radios I m new to the radio frequency field and like to learn more about it How can I order that issue It seems that some people out there are having problems assembling the pro jects in your magazine It could be a communications problem between the authors and the editors would like to suggest that you keep the explana lions simple and don t use abbre viations A project like to see is an emer gency ignition system for cars with elec tronic ignitions commonly known as a hot box I m looking forward to future articles T S Brooklyn NY Back issues of Hands on Electron _ PB iq Reprint Bookstore See the ordering cou pon on page 102 for more information Buzzing About CPM lam writing about of comput ers Some of us are not afraid of com puters We re madder than bumble bee at how low you and other maga zines have ma
139. been introducing one product after another during the past year First came the FastTRAP fol lowed by the PC Trac followed by the PDA a card for converting any serial mouse to a bus mouse The FastTRAP and the PC Trac are both three button devices built around trackbails Essentially a trackball is a mouse lying on its back The advantage of a trackball over a mouse is that you don t need a clean surface on which to operate the device you can even operate it on your lap The disadvantage is that some operations that are easily performed with a mouse can be difficult with a trackball For example dragging wherein you continually press a button while moving the mouse is problematic because it s hard to press a button and move the trackball simultaneously However the MicroSpeed trackballs have special emula tion modes that simplify dragging You press the middle The FastTRAP is nearly identical to the PC Trac but adds a vertically oriented trackwheel The trackwheel may be used for 3 D CAD work or for emulating various keystrokes in other programs simulating and Paon for example 8861 H38O120 o HANDS ON ELECTRONICS o button which is not normally used anyway then press and release the drag button The device then acts as if the button was still being pressed To terminate drag mode you press the drag button again Both devices emulate the Microsoft mouse in hardware so software compatibi
140. better perfor mance than serial versions One company MicroSpeed has introduced an adapter card called the PDA that allows you to use several varieties of serial mice Microsoft Logi Tech etc as bus mice The PDA is discussed later on in this article Microsoft has a third interface method called the InPort that is provided on the company s Mach 10 and Mach 20 accelerator cards on accelerator cards from PC Tech nologies and on other devices from other companies The advantage of an nPort mouse is that it requires neither a serial port nor an extra expansion slot just for the mouse interface introduced a new hardware mouse interface with the PS 2 line of computers some but not all vendors support the PS 2 interface Mechanisms The underlying technology affects the overall feel and usability of a mouse For example most mice are opto mechanical devices in which slotted wheels interrupt beams of light to provide horizontal and vertical motion informa tion Depending on the environment in which they re used dust may collect inside the mouse and impair operation So an opto mechanical mouse probably may need to be cleaned occasionally On the other hand a purely optically driven device like MSC s PC Mouse has no moving parts so it doesn t require cleaning However it does require a special pad with etched lines that reflect light in various ways If your desk tends to get messy keeping track of the
141. caler is available direct from Avocado Computer 17352 Yorkshire Ave Yorba Linda CA 92686 The postpaid price meaning all shipping and handling charges are included is 62 95 For more information circle No 82 on the Free Information Card goo Y o ins This ist the mother ship told you we were riding the wrong beam in ELLIS ON ANTIQUE RADIO Continued from page 85 Without the set s schematic would never have known that the unit was sup posed to be a 33K resistor The color code was unreadable and because of the overheating the resistance had al most doubled 1 measured it at 65K replaced that part with one of the proper value making a mental note to check for overheating next time I turned on the set Whatever circuit condition had caused the original overheating might still be a problem also took a close look at the wiring for the two replacement electrolytic ca pacitors It was very sloppily done and such an excess of solder was used in making the joints that shorts to adJacent terminals were only narrowly avoided 1 figured that if the wiring was so care lessly performed it might be tech nically incorrect as well Here s how the set appears as we conclude this month s restoration work The in stallation of a proper G type tube in the shield can behind the power trans former gives the grid wire enough clearance without pinching t
142. came along by using the COPYIIPC software from Central Fig 1 The directory for the supplied software shows both the copy protection programs and the commands which have an M prefix that are used when pro cessing Macintosh disks and software Enter Big Mac Well when you lick one problem another is certain to arise Sometime during the last year or so the Macintosh computer got a strong toehold in busi ness Until then the IBM PC was vir tually the standard of reference for business use because the best of the business programs were written forthe PC There were few quality business HANDS ON ELECTRONICS o Point Software COPYIIPC could make backup of most protected software And as fast as a new protection scheme was introduced COPYIIPC was up graded to bypass the protection So I can still use software for which there is no longer any trace of a distributor programs for the Macintosh On the other hand because of its graphics ca pability and ease of use the Macintosh was favored by schools hackers and the new generation of graphic artists But within the past year much of the heavy weight business software has The Deluxe Option Board is a half size adapter that plugs into the computer The universal matching cable shown is provided with the board PS 2 Models 25 and 30 as well as most IBM compatible computers to make
143. constant will be too long for Q3 to respond to a fast moving intruder There are several other sensors that can be used to detect an intruder and turn on the Audible Critter Chaser cir cuit An ultrasonic or IR motion detec tor can be used to activate the Chaser or a mirror and IR light rope could be placed around a garden to trigger the sounder Pest Zapper The circuit shown in Fig 4 the Pest Zapper is offered as a last resort to help get rid of the most stubborn of intruders The heart of the circuit is a Model coil which can be found at auto salvage yards A Model T coil is an automobile ignition coil that dif fers slightly from those used in modern cars Similar coils can be manufactured by placing a buzzer in series with the primary of the coil and placing a ca pacitor across the buzzer to reduce any arcing To conserve battery power the T coil is turned on and off by a low fre quency UJT oscillator Maximum bat tery drain occurs only when the SCR turns the coil on for a brief period of time During the majority of the time little current is taken from the power source 12V OUTPUT GROUNDING ROO Fig 4 The Pest Zapper is built around a model T coil To conserve battery power the coil is turned on and off by a UJT oscillator The operation of the Zapper is very simple Components R20 R24 and C7 set the
144. d by a switch able noise elimination system Heat dissipation is provided by a double layered RF heat sink reducing the chances of power transistor failure Other features include two channel memory for instant access to channels 9 and 19 and a large high intensity LED channel readout The Model 77 158 with Mic ro Tune ll costs 219 00 For more information contact Midland International Con sumer Communications Division 1690 North Topping Kansas City MO 64120 Continued on page 27 99 CHEMICAL SOLUTIONS FREE CHEMTRONICS CATALOG Comprehensive new source for over 200 products used in electronic man ufacturing and field service Precision cleaning agents flux removers bulk solvents circuit refrigerants precision dusters non residual wipers foam swabs premoistened pads swabs antistatic compounds conformal coat ings lubricants adhesives desolder ing braids rosin core solder and solder masking agents Complete with tech nical specifications and application guide Chemtronics inc t 681 Old Willets Path Hauppauge N Y 11788 516 582 3322 a gt 5 5 1 su nd 9 CIRCLE 6 FREE INFORMATION CARD 8861 H3HOLOO HANDS ON ELECTRONICS NO e AVOCADO COMPUTER GRAYSCALER Crisp composite monochrome with 16 shades of brightness comes alive directly from your color graphics card and RGB port 2 Te BH
145. de us feel about our old CPM computers Long long ago you were all push ing those CPM computers Now that DOS has come along you ve forgotten the old CPM users Why should you when we paid just as much for our CPM computers S P Hayward I no longer drive 1964 Rambler must admit that Hl miss it but the wheels have today are more to mv liking 1 like air conditioning 1 like power win dows like the goodies of today By the same token 1 miss old H89 Heathkit computer but the current gen eration of MS DOS machines and the new 5 2 machines are clearly supe rior it seems that the majority of coin puter users agree We haven t forgot ten US just time to move on Crossed Channels The output channel on my cable TV converter is Channel 3 but my televi sion set automatically goes to Channel 2 every time it s turned on When turn on the box by remote the TV goes to the wrong channel and have to get up to adjust it need an RF modulator to put in cir cuit with the cable box or one that goes in line with the box and the TV seen them tor Channels 3 and 4 but never for Channel 2 Do you know where could buy one or how I could build one M S Apple Valley MN Most sets including the newer electronically tuned ones have a fine tuning control Adjust that so that Chan nel 3 is received at the Channel 2 posi tion Public Servants
146. ding plans for sev eral programmers and erasers Other projects featured in this 230 page book are a Boole s Box a keyboard encoder a ROM drive speech and music synthesiz ers and an EPROM program tester The step by step plans give home electronics robotics and computer experimenters hands on understanding of how EPROMs work Complete specifications and pin outs for 19 popular PROMs EEPROMs and EPROMS in current use are included in periments with EPROMS The book also explores commercially available program mers and erasers and provides an over 1 view of alternate memory technologies Al though the book is aimed at intermediate to experienced hobbyists three appendi ces building an EPROM project IC data sheets anda list of suppliers provide guid ance for beginners and helpful tips for all readers Experiments with EPROMS costs 16 60 in paperback or 24 95 in hardcover from Tab Books Inc Blue Ridge Summit PA 17294 0850 Tel 1 800 233 1128 CIRCLE 98 ON FREE INFORMATION CARD p AN INTRODUCTION TO ANTENNA THEORY by H C Wright When any conducting body is exposed to a radio wave it will have electrical currents induced into it Conversely any conductor carrying currents will radiate Thus many common objects can be used as antennas The experimenter can test his ideas and innovations particularly with TV and CB wave lengths with little more th
147. drives must be physically configured as A and B both drives must be internal not connected to an external drive port support is guaranteed for 3 5 inch BM drives mixed results were attained on compatible brands you cannot read from a 360K or 720K drive and write to a 1 2 or 1 44 Meg drive you cannot read from or write to 1 2 diskettes 5 25 inch nor write to 1 44 Meg dis kettes 5 25 inch In a typical PC XT configuration with a 5 25 inch floppy and a hard disk a 3 5 inch drive can be installed inter nally as the B drive The option board automatically recognizes either single or double sided 3 5 inch Macintosh disks Of course the 3 5 inch drive can be used as a conventional IBM drive have barely touched on the applica tions of the COPYIIPC Deluxe Option Board For more information write to Central Point Software Inc 15220 N W Greenbrier Pkwy 200 Beaver OR 97006 Or call 503 690 8090 for information E Try the 1 io em Elecironics bulletin board system RE BBS 516 293 2203 The more you use it the more useful it becomes We support 300 and 1200 baud operation Parameters 8N1 8 data bits no parity 1 stop bit or 7E1 7 data bits even parity 1 stop bit Add yourself to our user files to increase your access Communicate with other R E readers Leave your comments on R E with the SYSOP RE BBS 516 293 2283 8861 H380100 j
148. dth The PM2195 consists of a four input selector switch and four attenuator probes It is compact enough to be plugged directly into the oscilloscope input socket The four probe inputs have individual adjustment facilities so each can be tuned for optimum response en suring a bandwidth of 400 MHz dB for oscilloscopes with input capacitances of less than 10 pF CIRCLE 29 ON FREE INFORMATION CARD The probe switch is controlled by the PM 2125 Probe Switch Driver which can drive up to four PM 2195 modules Therefore a single channel oscilloscope accept up to four separate inputs and a four channel oscilloscope can ac cept up to 16 separate inputs Simple command strings facilitate programming and a choice of operating modes individual probe selection or parallel probe switching is offered The PM 2195 and PM 2125 are part of the Philips System 21 line of switch ing and 1 O modules Based on a building block concept modules can be pur chased as needed and reconfigured to accommodate future applications Mod ules can be connected by snapping them together or with cables The PM 2195 Probe Switch is priced at 650 00 and the PM 2125 Probe Switch Driver is 450 00 For further information contact John Fluke Mfg Inc P O Box C9090 Everett WA 98206 Tel 800 443 5853 E New Scanner 100 Channels 7 ncludes antenna rechargeable battery Charger adaptor amp belt clip Full ra
149. e unit Price 440 CIRCLE 59 ON FREE INFORMATION CARD Plus U S A Uovo Nuovo Don t ask for a transiation of Uovo Nuovo we re not even sure what the product it names is From the hyperactive design department of Plus U S A Corp 10 Dr Closter NJ 07624 it s described as an Executive Toy a concept which we reserve comment The Nuovo encases fold in elements similar to the famed Swiss Army Knife There s a diminutive roulette set up poker set and a domino set that includes checkers and dice There s aiso a survival kit version featuring compass thermometer fish line string flashlight hooks and sinkers It goes without saying that fans of this kind of thing should really go for the hook line and sinker aspect Price 14 95 CIRCLE 60 ON FREE INFORMATION CARD Electronic Auto Compass If we re ever involved in an emergency evacuation that requires driving over miles of unmarked terrain we hope we re fortunate enough to be in a vehicle equipped with the Electronic Auto Compass offered by Hammacher Schlemmer 747 E 57th St New York NY 10022 That practical navigation aid uses the quadrature circuitry used on board commercial aircraft It features a 360 degree graphic display of the vehicle s heading and includes a separate direction sensor mounted on dashboard or windshield Plugged into a cigarette lighter the com pass will measure the earth s magnetic field in two directions automatically compensa
150. e Decks Onkyo has added two high pertor mance models to their dubbing cassette deck line Models TA RW470 and 7A RW490 have Dolby B and noise reduction systems assuring com patibility with other decks and pre re corded tapes TA RW490 also features Dolby HX Pro for increased high frequency capability and reduced distortion Both models use dual motor logic controlled transports and provide quick auto reverse for recording or playback A more sensitive infrared sensor in stead of a mechanical sensor ts used to trigger direction change at the begin ning of the leader tape resulting in very short gaps between sides The decks are compatible with Onkyo s Remote Inter active remote control format which uses bi directional digital data trans mission to allow interaction between many components CIRCLE 47 ON FREE INFORMATION CARD CIRCLE 12 ON FREE INFORMATION CARD FREE New Catalog of Hard To Find Precision Tools Jensen s new catalog is jam packed with more than 2 000 quality items Your single source for hard to find precision tools used by electronic technicians scientists engineers schools instrument mechanics laboratories and government agen cies This popular catalog also con tains Jensen s world famous line of more than 40 tool kits Call or write for your free copy today 7815 S 46th Street JENSEN Phoenix AZ 85044 TOOLS INC 602 968 6241 Gate ef Gar
151. e character rate of from IO to 99 words per minute WPM although the rate be slower than 10 WPM The reason for sending the characters at a speed of at least 10 WPM is to avoid the 7 8 WPM conceptual plateau that is well known to Morse code instructors The Morse Coach keeps track of your errors and re transmits characters that give you trouble more and more often to increase your proficiency The program also keeps track of your progress during any one session and reports the data on the screen The Morse Coach is a lot better than practice cassette tapes because with tapes there is a tendency to memorize the taped code n other words your progress is only a reflection of your ability to memorize a single tape Prod ucts such as Morse Coach overcome that limitation by randomizing the prac tice sessions The Morse Coach is ideal for practicing for higher class amateur radio licenses as well as practicing for those speed demon traffic nets that might be heard on 80 meter CW every night Radio Teletype Ever hear one of those bee boo beep beep beep stations that operate at around 14 080 kHz on the 20 meter band Those are radioteletype amateur radio stations If you buy the right terminal unit and software then any Commodore 64 or 128 Apple II or IBM PC or clone can turn your setup into a RTTY station Although the con version to RTTY was once a big
152. e end of the coil s lead through the hole in the end cap and then set the coil in the end cap INSULATEO ALLIGATOR mms CLIP FOR E TAPPING COIL L1 FAHNESTOCK CLIP NO 12 COPPER NO 26 OR 28 WIRE Y SOLIO WIRE 1 3 4 N 5 8 pms OOWEL ALUMINUM T ROO SPACER 7 9 INCH P v et LENGTH TEST TINCH 6 32 SCREWS WIRE CIRCLE TO C5 ALL OIMENSIONS IN INCHES Fig 7 The spark gap is formed by mounting two fahnestock clips to the 9 inch circular deck one tied to the main grounding point and the other connected to an alligator clip which is used to change taps on 11 Take the other end cap and drill a hole in the center to clear a 8 32 screw and mount a feed through insulator see photo on top Select a 448 32 screw long enough to stick through the top of the insulator by about 12 inch and grind the end to a nice sharp point Connect the top end of the secondary coil to the bottom of the 48 32 screw with a small solder lug and tighten in place Place the cap on top of the coil The spark gap is shown in Fig 7 Two holes are drilled to clear a 46 32 screw to match the drawing in Fig 4 Two Continued on page 102 signal sniffer by adding a good antenna With a good antenna you can hear those weak but often times very interesting stations such as those operated by many state universities during the day At night you can hear stations from thousands of miles away e
153. e lamp s filament to the outer edge of the glass envelope Neon lamps glow around the coil without wires Experimenting with HANDS ON ELECTRONICS e PAGES MONTH YEAR the coil can be an almost endless adven ture But remember always put safety TOTAL PAGES a 50 each TOTAL PRICE first MAIL TO Hands on Electronics 1 Reprint Bookstore Box 4079 Farmingdale NY 11735 All payments must be in U S funds SHIPPING CHARGES IN USA amp CANADA First aid kits are fine for some emergen 00110 5 00 1 25 30 01 to 40 00 5 00 SORRY We only ship to cies But what if you were choking Having 5 011010 00 2 00 40 01 to 50 00 6 00 USA amp Canada heart attack Or a stroke This kit would be 10 01 to 20 00 93 00 50 01 and above 7 50 useless 20 01 to 30 00 4 00 Call the Red Cross We ll teach you and your employees how to save a life pa Qu From ork safety to CPR vou can count on ates lax ew Yor ate Hesidents on VEINS 2220222 the Red Cross h l 7 Vill 2 i Shipping Charge see i A Red C Total Enclosed i i Address City State Zip 10 88 Ad AP enc Secep NEW PRODUCTS Continued from page 27 Mini Mobile Scanner Measuring just l 5 inche
154. e same width and depth but the height is about half that of the larger one One difference between the photographs and drawings can be seen in the edges of the top and bottom pieces Those parts in the towers shown in the photographs were run through a shaper to add an interesting curve to the edges If a shaper isn t available a simple square edge will suffice You can cover the raw edges of the plywood with thin strips of wood veneer which is available at building supply stores Or you can alter the dimensions of the top and bottom pieces and add a solid wood trim of your own choice Speaker Board Construction Start out by making the woofer and tweeter cut outs on the speaker board using the dimensions given in Fig The speaker board requires careful handling because of the small amount of material left at each side of the woofer hole Set the woofer in the cut out and rotate it until two opposite mount ing holes in the woofer frame are in a horizontal position over the narrow sections of the board Those two holes will not be used Mark the locations of the other bolt holes and remove TABLE 1 SECTION INFORMATION 2 4 2 4 2 2 B B 4 14 4 2 8 8 4 4 6 8 1 2 gt 2 15 16 OIA 1 BREAK POINTS 2 3 8 OIA F it SEE TEXT FOR SQUARE PORT DIMENSIONS Fig 1 All dimensions for the speaker board A and the faceplate B are given in inches Allow your saw to cut thro
155. e values should also be equal because the current flowing in both is the same That is why when the output voltage is dropped to one half the load resistance equals the internal resistance Remember those important techniques when working with voltage sources They will help you determine internal im pedances and help you to calculate them Now we are ready to take a look at Thevenin s theorem itself Thevenin s Theorem Thevenin s theorem describes a process of converting any complex electrical or electronic circuit into a simple equiv alent circuit consisting of a single voltage source in series with an internal impedance other words a complex elec tronic circuit represented by the box in Fig 6A would be converted into a DC or AC voltage source as illustrated in Fig 6B or 6C The equivalent circuits consist of an equivalent or Thevenin s voltage source designated V in series with an equivalent internal resistance designated the 5 resis tance R The mathematical process of converting the larger more complex circuit into its Thevenin s equivalent is called a circuit The mathematical process of Thevenin s theorem takes the voltages and resistances of the complex electronic circuit and uses them to calculate V and R That s what we want to show you how to do here Let s start with a relatively simple circuit but one that is widely used and that Thevenin s theorem makes
156. e with voltage divider relationships 8861 H38O120 d a HANDS ON ELECTRONICS j One of the main problems in dealing with voltage sources is that it is often very difficult to determine the internal impedance of a source For example how do you know what the internal resistance of a battery is We know that it is extremely low when the battery is good and in most cases it can be ignored or assumed to be zero But as the battery discharges the internal resistance increases That s why when a battery goes bad its output voltage drops to a very low level When you connect a load to it the current that flows produces a large internal voltage drop leaving less voltage at the battery terminals for the external circuit Unfortunately you just can t get an ohmmeter and connect it to a battery and expect to measure the internal resistance Neither can you do that on any other kind of voltage source nor AC generator Yet it is important to be able to determine what that internal impedance is so that you can perform the circuit analysis Well there is a way to determine the internal impedance although not by direct measurement Let s take an example but this time let s use an AC voltage source Refer to Fig 4 There is an AC generator with an internal impedance of Rg It might be a signal generator or function generator used for bench testing Let s assume for a moment that we don t know what the internal impedance is Through
157. ece and crophone during conversations Back ground noise around the Swisstel isn t shielded in tbe least and that becomes MENU DUE OWN Vn another distraction Positive reaction did come from one user a teen ager who was intrigued by its thin lines and the way it hugs the side of the user s face He was even more delighted when Swisstel s tele vision ads began appearing which we guess points up the phone s real strong point marketing strategy as opposed to practical design It s Curious mix of the advanced and the inept but that s apparently not sup posed to matter to the 18 to 47 year old affluent women identified in marketing in formation as the Swisstel s target consum ers But we have our doubts Telephones should be nice to look at but the invisible quality of audio pertormance would seem to be the real point one we don t think the Swisstel Telephone makes this issue John Swenson and Marilyn Ciafone Ccpyright 1988 by Gernsback Publications All rights reserved 8861 H38O012O e N z ie D ob HANDS ON ELECTRONICS Eight is Enough SONY 8 mm VIDEO CAMCORDER CCD V5 Manufactured by Sony Corp of America Sony Drive Park Ridge NJ 07658 Price 1 500 After a little more than four years on the market can it be said that the 8 mm video format has arrived Well yes and no While it hasn t revolutionized video in quite the way that was predicted
158. ed by a composite monitor and the display is fragmented a nice way of say ing it is garbage On the other hand the Grayscaler con verts the RGBI Red Green Blue Inten sity digital signals to analog and integrates the display with the horizontal and vertical sync signals into a composite signal which then feeds a line driver that provides a low impedance output for a conventional composite monitor Even if the program produces what was originally intended as a graphics display processing by the Grayscaler provides a usable con ventional composite signal A Cubic Inch The Grayscaler takes up less than cu bic inch of space It plugs directly into the Continued on page 100 The cable from the composite monitor simply plugs into the standard phono type jack on the rear of the unit NEW PRODUCTS Continued from page 25 Medium Speed Analog Input Board MetraBvte s DAS 8PGA board is an 8 channel 12 bit analog input board for the IBM PC XT AT and compatibles The eight differential input channels of ler nine software selectable input ranges The DAS 8PGA provides four digital output bits and three digital input bits A three channel counter timer can be used as A D pacer clock and to meas ure or generate frequency measure pulse width and count events Complete ac cess to the computer s interrupt bus is available at the board s O connector CIRCLE 100 ON FREE INFORMATION CARD
159. ed fiber washer steel screw 1 12 to 2 inch magnet see text magnet wire 20 gauge Y pound spool brass strip clear glass or plastic vial line cord heat shrink tubing hardware solder etc unit was a center tapped 12 volt secondary type Using either the 6 or 12 volt output did not seem to make much ofa difference The author used the 6 volt arrangement The primary of the transformer is connected to a 117 VAC line cord and a momentary contact pushbutton switch neon lamp may be added to the circuit parallel to the transformer primary to indicate that the unit is on A momentary contact switch is used for a good reason Be sure to use one to avoid overheating the coil through overuse This is the magnet caught in flight It moves very rapidly inside the vial in a helter skelter fashion a Shown here is the circuit mounted and ready to operate Note the large air space around the magnetic coil That helps keep it cool Do not use a cabinet that is too small The electromagnetic coil becomes very hot very quickly and the momentary switch prevents the unit from being left on unattended Also resist the temptation to operate the unit for more than 20 or 30 seconds at a time The connections between the transformer and the coil can be soldered and insulated before the transformer is mounted The rest of the work may have to wait until everything is in place If the line cord does not fit tightly in the grommet tie
160. edy or high tech hasn t the American telephone consumer just about seen it all Not according to Swisstel described in publicity literature as a subsidiary of As com the Swiss telecommunications giant Since the spring the company has been introducing the Swisstel Telephone to Americans via extensive TV and maga zine advertising The thin palm size one piece instrument is labeled as nothing less than an extension of you we weren t kidding about the telephone being pro moted as a human organ Despite some innovative home phone features the Swisstel in red black white pink blue and transparent models is being promoted primarily as a decorator accessory Besides those six styles it s also available black with rainbow dots and patterned cases called domi no pink and stratos Built in Switzerland by people used to working on Small things the Swisstel s slender half inch thick silhouette is the re sult of robotically installed state ot the art surface mounted circuitry according to the company The instrument boasts 13 the Swiss apparently aren t superstitious features including redial access to call waiting and third party calling a PULSE TONE Switch and RING VOLUME control Its fluttering bell like ring sounds very Eu ropean and is a welcome contrast to harsh electronic tones Unusual home instrument features in clude a CALL HOLDING button and a multi function co
161. eeping prevents a whole lot of troubleshooting Friedman on Computers a dual purpose device backs up floppies and provides IBM Macintosh compatibility Saxon on Scanners get nine band coverage and 16 channel programmability from a handheld scanner Jensen on DXing pioneer shortwave program celebrates its 60th birthday Carr on Ham Radio ham radio joins forces with computers to improve the communications hobby Circuit Circus electronic pest controllers take some of the drudgery out of maintaining your home Towers 42 DEPARTMENTS Bii Editorial change is inevitable Letter Box the place to let yourself be heard Electronics Library spotlighting a knowledge storehouse New Products Showcase trends in the electronics marketplace FactCards a fingertip reference for the electronics hobbyist GIZMO Special Section what s new in electronic doo dads Free Information Card when in doubt sound the manufacturer out Locating Defective Motors page 66 8861 HAGO1L00 u HANDS ON ELECTRONICS The for the Electronics Activist Change is Inevitable Letters from our readers tell us to never change our editorial format What they see in our magazine and what it does for them iS more often than not exactly what they want Of course we love to hear things like that compliments are always welcome But we like to hear your criticisms too Its your input that make
162. ei ther the program its files nor the disk lormat was compatible between sys tems Not only was software com patibility lacking but much of the software was protected which meant that the user could not make copies of the distribution disk While proponents of protection put and for those rarities Central Point Software had a special disk adapter that plugged into the PC and bypassed the normal disk controller allowing vir tually all software to be backed up files are usually 99 9 100 compati ble For example the data text files of Macintosh and versions of Micro soft s Word are essentially compatible files between the Macintosh and the Ar N dir IBM computers Although the easiest way to inter forth many rational and justified argu ments they conveniently avoided the problem of something going wrong OBSETUP EXE 7940 You could interchange the Word s data Volume drive is DLX BRD Directory of Ar change data is by disk even if the disks uu ee 41 TM 5 14 88 9 48 5 y with the distribution disk such situa Tc EXE 66249 4 11 88 10 02 are the same 3 5 inch format IBM and tions the user was left high and dry 4 arii Macintosh disks aren t compatible You ince I have been i rsonal com 33203 4 11 88 10 08 since 1 have been into personal com d can t read from or write to a disk if
163. ended that you choose one of the other circuits in the article and try to solve it without referring to the text until you are finished Compute the voltage across RI V V 2 IRI 1 100 10 V Find the voltage across V5 By Kirchhoff s law that is V V V 25 10 15 volts Calculate the current in R3 and R4 I 4 14 4 3 15 300 05A Calculate the output voltage across R4 and A B V4 Vin Va by 4 R4 05 150 7 5 volts c Calculate the Thevenin s equivalent resistance Short R3 and R4 are in series R 4 R3 R4 150 150 300 ohms Also 4 300 ohms in parallel with R2 is 4 300 2 150 ohms With V shorted appears in parallel with R2 and R3 R4 in series The total resistance is 150 in parallel with 100 or Rn RIR 4 RI R334 100 150 100 250 15000 350 42 86 ohms d The equivalent circuit is shown in Fig 18C 8861 HAGOLOO HANDS ON ELECTRONICS co 1 JUMPING BEANS Fred Astaire even at his best never pulled the moves you ll see this project do By Stan Czarnik lic chunk in a glass vial Seal the vial Place the vial on a black box and the chunk vibrates wildly with no visible means of propulsion The chunk is a magnet the box emits an alternating magnetic field and so the magnet vibrates Even to those who know exactly what s going on this simple trick seems strangely amusi
164. enin s Theorem in circuit analysis At last we can draw the full Thevenin s equivalent which is illustrated in Fig 15 A DC voltage of 4 volts is connected in series with its resistance of 8 8 ohms Our load resistance is 4 ohms Calculating the voltage across the load resistance is now easy To do that we first find the total circuit resistance which in this case is the Thevenin s equivalent resistance plus the load resistance or R 4 8 8 12 8 ohms Next we find the total circuit current with Ohm s law l V Rr 4 12 8 3125 amperes Now the voltage across R is simply that current multiplied by the load resistance or V IR 3125 4 1 25 volts Exercise Problem 2 Now have one more go at using Thevenin s theorem yourself Refer to Fig 16 Calculate the Thevenin s equivalent voltage and resistance R1 10082 15082 R2 30082 L7 1002 Fig 16 Follow the basic steps for using Thevenin s Theorem when working the practice problem for this circuit Next month we ll cover some of the more interesting techniques for circuit analysis Till then practice what you ve learned and Theveninize Answers l Refer to Fig 17A a Remove the load resistance R b Calculate the Thevenin s equivalent voltage V across R3 Vin Va Calculate the total circuit resistance R 1 R2 and R3 are in series to produce R R2 R3 60 120 180 ohms is in parallel with S
165. ent with today s latest electronic circuitry Just how well this innovative learning approach meets the challenge of the new electronics is confirmed by those who have already completed the Series You have put me right into the middle of an extraordinary learning experience With each lab exercise have gained a new understanding of the intricacies of today s electronics Or For me the Series was just the answer I felt confident within my specialty but my grasp of other areas of electronics was slipping away Your Series helped me upgrade my knowledge of the latest electronics concepts Or this from a company director of training We manu facture sophisticated electronic products with a lot of people in sales assembly and purchasing McGraw Hill has answered a real need in helping our employees see the total picture They now communicate with customers and each other more effectively Your Involvement in the New Electronics Begins Immediately You master one subject at a time with 15 McGraw Hill Concept Modules sent to you one force the meaning of each important point Carefully indexed binders conveniently house all this material as well as the instruc tions that will guide you through your hands on lab experiments Throughout your Series laboratory every 4 to 6 weeks You waste no time on extraneous materials or outdated history It s an entertaining lively nontraditional approach to the most
166. er services in Europe It s coming to North America and it s a new trend setting feature never before offered on tone generators By it we guess what s meant are those new services If you want to be prepared for the future the gold anodized metal Dial It is apparently the tone generator to have Price 19 95 CIRCLE 56 ON FREE INFORMATION CARD with an optional external battery pack De spite its small size the video portion of the system offers high speed picture search a linear time counter with tape position dis played in hours minutes and seconds a one day one event timer and a power off timer The unit can also be connected to a large screen monitor or TV Its television component features a built in VHF UHF tuner a telescoping an tenna and a three inch measured diago nally color LCD screen with an active matrix system for superior sharpness con trast and color purity There s also a backlight behind the screen The GV 8 Video Walkman has a suggested retail price of 1 300 Other products developed as 8 mm personal video equipment include desktop TV VCR EV DTI 1 700 and a basic color video camera CCD G 750 The EV DTI features five inch Trinitron color monitor and a 8 mm VCR with tuner and timer capable of seven day three event time shift recording The unit includes a remote control and features on screen programming display
167. ering audio power to the loudspeaker The max imum audio output is 2 watts into 4 ohms The schematic diagram of the mod ule is shown in Fig 1 Note that some of the symbols and terminology used there and in the Parts List differ from what you are used to seeing in Hands on Electronics That s been done to con form to the style used in the kit s parts list and printed circuit board For ex ample the kit s distributor used RV to indicate a potentiometer in our maga zine we would denote such a part as R There are numerous other changes too However if you read carefully there should be no problem in following the text and diagrams The basics of the module s operation are as follows Sound is detected by condenser microphone MICI see Fig 1 an analog device and the audio sig nal is sent to C3 where speech or other sound is digitally sampled at a rate determined by an internal clock The volume and frequency variations of the audio signal are converted to digital bit information that is sequentially stored in two RAM memories and 2 Those RAM memories hold 10 to 12 seconds of information The quality of the audio reproduction is determined largely by the sampling rate At the lowest sampling rate pro vided by the module maximum storage time is achieved but at the expense of audio quality Higher quality audio is available by increasing the sampling rate but doing that cuts the maximu
168. es Part 3 is a guide to ad vanced features such as style sheets glos saries macros tables and indexing out lining and columns There are also appendi ces covering installation keyboard and mouse references windows and pageview features and the differences between Ver sion 3 and Version 4 Microsoft Word The Complete Reference contains 554 pages and is available for 24 95 from Osborne McGraw Hill 2600 Tenth Street Berkeley CA 94710 CIRCLE 96 ON FREE INFORMATION CARD PRACTICAL MIDI HANDBOOK By R A Penfold The Musical Instrument Digital Interface MIDI is a means of swapping information between sSuitably equipped electronic mu sical instruments andis often used for com puter control of instruments 15 main ad vantage is that itis a true standard adopted by many manufacturers so that any instru ment equipped with MIDI sockets will work with any other piece of MIDI equipment from any manufacturer MIDI has been surrounded by misun derstanding however and the highly technical user manuals accompanying the equipment often add to the confusion The Practical MIDI Handbook is intended to clar ify things for the reader It is aimed at musi cians technicians and enthusiasts who want to explore the capabilities of MIDI but are prevented from doing so because they have little prior knowledge of electronics or computers The basics of MIDI are explained includ ing such things as interconnecting a sy
169. es We just wish they came in sturdier ones 8861 H380120 aime 4 mr HANDS ON ELECTRONICS made the big ticket camcorder including 8 mm format units the fastest selling product in all of videodom Anyone who has sat through a sleep inducing unedited videotape of a wedding ceremony or vacation trip will understand the potential of an editing deck Especially if the drowsy cassette was one of your own The Video Cut 10 connects an 8 mm camcorder or player to any VCR includ ing VHS format Equipped with a fold up LCD screen the unit s circuitry and com puter technology allows the user to mark selected segments of a recorded cassette up to 50 different segments or which can then be rearranged sequentially deleted duplicated and modified Slow motion and still picture treatments are possible if the 8 mm player used is equipped with those capabilities Once the edited program is organized in the Cut 10 memory the user can preview the entire sequence before actually com mitting it to cassette An editing deck con trol labeled PERFORM transfers the created sequence of segments from the 8 mm tape in the camcorder onto the cassette in the video recorder The Cut 10 memory stores only the cut in cut out that is begin ning and end of scene data organizing it via pulses read from the tape counter of
170. es a fixed output voltage to a load That voltage of course will cause current to flow through the load and in that way produce some i 4A RI Ly 7A R2 1 23A 1 2A R3 Fig B Kirchhoff s current law for parallel circuits simply states that the source current must equal the sum of the current through all branches The electrons must remain in the circuit and return to the current source the voltages across R2 and R3 In Fig the source voltage is 8 6 5 2 3 8 volts You can also rearrange the formula to solve for one of the resistor voltages if the source voltage and the other compo nent voltages are known For example FI V EN V Kirchhoff s current law for parallel circuits states The sum of the currents in the branches of a parallel circuit is equal to the total line current drawn from the source In Fig B that is expressed as 1 1 1 where I is the total line current supplied by the battery and l I and I are the individual branch currents in the resistors In that case the total line current is 4 7 1 2 2 3 You also rearrange the formula to solve for any branch current To find I for example I I I 1 0 2 3 4 12 7 The three laws are used the solution to almost any circuit problem Commit them to memory and apply them as needed useful end effect The problem is most voltage sources are not ideal They
171. ex Design Double chamber reflex designs have been around for years but are often overlooked The compartments of a double chamber box are tuned to two frequencies one an octave above the other Double tuning keeps the woofer s under contro and reduces distortion At the frequency of the lower resonance the two chambers act as one and the driver sees their combined volumes as the real size of the box Doubie chamber reflex enclosures were originally designed for use with any good eight inch speaker with a specified volume of about 2 7 cubic feet generous enough to avoid the problems that occur when a box 15 too small That is one of the advantages of the double chamber design it works well even without a careful match between the enclosure and the driver Now modern design techniques allow us to tailor the enclosure to suit any specific driver However the techniques involved are beyond ths scope of this article Instead we will concen trate on a design that the author has found successful It is one that can be readily reproduced and uses easy to obtain parts The speaker described here consists of an eight inch woofer and a one inch tweeter in a double chamber reflex tower that s 10 inches wide x 40 inchestall x 12 4 inches deep The woofer is the Precision TX 205 F made in the U S A the tweeter a soft dome Audax HD 100 D 25 Both the speakers and the crossover components are available from McGee Radio see the Parts List The to
172. f thermal recording paper Price 1 195 CIRCLE 66 ON FREE INFORMATION CARD Gizmo Bytes gt agp gnum p rd C Desk Revenger Portable Facsimile Unit 8861 H38O120 GIZMO Page9 5 Gizmo Bytes Personal Portable Copier Hand Held LCD TV Tapeless Answering Machine HANDS ON ELECTRONICS 56 Page10 GIZMO Ricoh Personal Portable Copier As the absolute bulk of copied material increases the size of copying machines appears to be shrinking The Ricoh Corp 5 Dedrick Pl West Caldwell NJ 07006 has joined the marketing fray with its Personal Portable Copier MC50 described as being about the size of a small notebook The unit powered by either AC current or batteries included will copy from thermal or plain paper as well as transparent sheets The 50 is placed directly over the image to be duplicated which can be previewed through a viewing glass The copied image will be the same dimensions as the window 3 inches by 6 4 inches In contrast to other small copiers it s not necessary to run the MC50 over the material being copied which according to Ricoh results in sharp distortion free images Copying takes about 15 seconds A couple of other Ricoh products introduced in conjunc tion with the MC50 expand the copier s uses An image controller IM A which interfaces between a personal computer and the MC
173. ffer some of the most competitive prices in the industry on nearly 11 000 of your most often needed items and they re all high quality products that perform as promised every time Or perhaps he was dealing with a supplier that couldn t deliver the parts he needed when he needed them If he had been buying from MCM he would have found that almost everything we offer is in stock ready to ship within 24 hours Don t let what happened to HERES Anderson happen to you ELECTRONICS Order your FREE ENTALUN Electronics catalog today and discover what a difference we can make in your business For your FREE copy A meee xL ire call TOLL FREE m 1 800 543 4330 In Ohio call 1 800 762 4315 In Alaska or Hawaii call 1 800 858 1849 MCM ELECTRONICS 858 E CONGRESS PARK OH CENTERVILLE OH 45459 4072 A PREMIER Company SOURCE NO HO 19 CIRCLE 14 ON FREE INFORMATION CARD 8861 H38O0100 HANDS ON ELECTRONICS e True RMS Multimeter The Fluke 87 handheld digital multi meter offers a powerful combination of measurement functions including fre quency duty cycle capacitance mini mum maximum average recording MIN MAX Alert and Input Alert The Input Alert safety feature warns the user when the leads are connected to the current jack while the meter is se lected for voltage or resistance The MIN MAX Alert pinpoints intermitte
174. fier further enhance its sound CIRCLE 41 ON FREE INFORMATION CARD The 9655 also has external op tional speaker outputs powered by a 5 watt amplifier and rear panel audio out puts for connection to a stereo system Two sets of audio and video terminals monitor terminal and an RF connector provide easy connection to other com ponents in an audio video system The suggested retail price for the Y M 965S is 899 00 For more infor mation contact Yamaha Electronics Corporation USA 6660 Orangethorpe Avenue Buena Park CA 90620 Cordless Phone The Excursion 500 1s an inexpensive full featured portable cordless phone It has battery low indicator LEDs tor power in use and charge a flash but ton a 750 toot operating range tone pulse switchable dialing and is hear ing aid compatible The telephone s call bar acts as one way pager When the call bar on the base is pressed the handset buzzes alerting the person with the handset e Now from NRI comes the first course of its kind anywhere Learn to use program and service today 5 digital electronic music equipment as you TA Now NRI puts you at the heart of the most exciting application of digital technology to date With NRI s new at home training in Electronic Music Technology you get hands on experience with the equipment that s revolutionizing the music industry Atari ST Series computer with built
175. gan cleaning by going over the chassis with a cloth kept moistened with soapy water and periodically wrung out A small screwdriver was used to poke the cloth into difficult cre vices like the space between adjacent coil cans As evidenced by the con dition of the wash water an astonishing amount of dirt was removed in just that manner The soap treatment was followed up by rubbing with Brasso a metal polish that also works well on glossy paint such as used by Zenith on most chassis of that period The Brasso was used not only on the chassis but also on all coil cans transformer cans and tube shields With the tubes carefully clean ed up using a damp cloth the shield cans firmly locked in place and the tuning eye tuning condenser bracket reinstalled the chassis top was begin ning to look quite presentable if not impressive A word of warning about cleaning tubes The type markings on most tubes of this period appear to be etched in the glass but they are apparently only sten ciled using some very easily removable paint One vigorous swipe of a damp cloth may be enough to completely obliterate the marking leaving the tube embarrassingly blank A word to the wise when you clean the tube care fully avoid the area around the stencil The Situation Underneath Conditions under the chassis were just about what you might expect of a radio that was probably stored in a base ment or garage for about thirty years and
176. ghtly against the inside top of the cabinet One way but not the only way of doing that involves bending the metal strip into the form of a U as shown in Photo 2 The base of the U should match the inside dimensions of the box along which you will be placing the bracket If the ends of the strip extend past the bottom of the cabinet they must be bent or cut The bracket can be mounted before anything further is done The circuit is very simple as you can see in Fig The electromagnet is connected to the secondary of a small power transformer The transformer the author used a Radio Shack 2 Here s the electromagnetic coil mounted the bracket hardware has been inserted to show the position of the holes used for mounting the unit in the cabinet S1 L Ti ET E i Fig 1 This is all it takes to build the Electronic Jumping Bean project This is one project that takes little time to build but many days to kick the habit of playing with it a Ee When the coil bracket is secured inside the cabinet you should make sure the coil is right up against the top of the cabinet A good snug fit along the sides is also desirable PARTS LIST FOR THE ELECTRONIC JUMPING BEAN L1 Electromagnet see text PL1 AC plug with line cord S1 Momentary contact pushbutton switch 1 6 or 12 volt power transformer such as Radio Shack 273 1352 Project box see text perforat
177. h one removable circuit board Additional boards can be pur chased separately Those models as well as the entire Powerace line of breadboarding labs feature internal power supplies logic monitors a clock generator data pulse sources logic level switches pulse generator and pulse detection with memory The Plus Board units have two sol derless breadboards with tie points laid on a 0 1 X 0 l inch matrix Those breadboards accept all DIP sizes and a wide variety of discrete compo nents with lead diameters of up to 032 inch There are 1 680 plug in tie points on each board accommodating up to eighteen 4 DIPs Mounted to an aluminum ground plane the boards are ideal for high frequency and high speed low noise circuits Circuits are protected by a short proof power supply and tused transformer primaries CIRCLE 43 ON FREE INFORMATION CARD The Models 202 and 203 part No 923202 and 923203 have a suggested retail price of 175 05 cach Further information is available from local 3M Electronic Specialty Products dis tributors or contact Electronic Spe cialty Products 3M Electronic Products Division 9325 Progress Parkway P O Box 540 Mentor OH 44060 Tel 800 321 9668 216 354 2101 in Ohio Tool Kit Jensen has improved their popular JTK 79 Electro Mechanical Tool designed for the performance of a wide variety of electronic and mechanical repair tasks The kit contain
178. has nothing at all to do with the motor Ja this article we ll show you how to find where a motor problem really lies and what you can do about it Checking out motor problems is easy when you have the correct test instruments and know how Replacing a defective motor is easy and can also be very satisfying So let s check out some of those dead units that have been collecting dust ROUND AND AROUND GOES DRIVING THE IDLER Defective Motor Tests One method of testing suspect motors is to use continuity checks Of course continuity measurements may not indicate the motor has dry or frozen bearings but it can tell you if you have an open winding Also the motor may have a shorted winding that will not be detected with continuity tests A more effective test you can perform is to measure the resistance of the windings Low ohmmeter readings across the motor terminals will indicate if the motor windings are open or normal Most small motors give a very low ohm meter reading The small motor may have a resistance of under 20 ohms If in doubt check the schematic diagram Also voltage measurements across the motor terminals may help you uncover a defective motor Check the low voltage supply source when a low or improper voltage is found at the motor terminals Some small motors may have an open resistor in series with the winding Fig 1 indicated by lack of voltage across its terminals Do not overlook a poor switch or wiring
179. he can top Sure enough checking the values of the replacements against those shown in the schematic 1 found that a 16 pF section had been wired into a portion of the circuit where an 8 unit should have been and vice versa So I switched them around changing the filter config uration back to the one intended by the set s designers And while I was at it 1 cleaned up the joints to get rid of the excess solder As a final touch I sprayed contact cleaner into the volume control band switch and tone control switch work ing all the controls back and forth to get the most effective cleaning action That would minimize control noise and er ratic effects caused by dirty contacts The Second Test Run With the deep cleaning accomplished and all of the obvious problems cor rected it was time to make another test When the radio warmed up was grati fied to find that it picked up a full com plement of broadcast stations without a trace of oscillation And switching to one of the shortwave bands formerly dead found it alive with signals However the tuning eye did not respond even when a strong signal was being received and there was no reception at all on the second shortwave band Those are problems that I ll try to have solved by next month when we ll have another installment of the restoration project But the progress that s been made so far is an excellent example of what consider to be one of the most i
180. he newer gen eration of radio enthusiasts this book tells an exciting story of the pioneers in the de velopment of radio Beginning with Marconi s wireless experi ments in 1895 Radio s First Two Decades describes the earlier discoveries of Maxwell and Hertz upon which Marconi based his experiments The story of how Marconi spanned the ocean is told illustrated with photographs of some of the actual equip ment used The book tells of Fessenden the first man to transmit the human voice By wireless DeForest the developer of the audion or vacuum tube and those men whose visions led to the beginning of broad casting It ends with the start of radio as we know it the establishment of station KDKA and the first public broadcasts of Sports music and political events to an eager public Radio s First Two Decades order No RFTD costs 4 75 including shipping It is by mail order available from Electronics Technology Today P O Box 240 Mas sapequa NY 11762 E CIRCLE 95 ON FREE INFORMATION CARD Science Brief THE GRAVITY OF THINGS A team of scientists will travel to Greenland in July to make some of the most sensitive geophysical measurements ever made of the Newtonian gravitational constant and to test a new theory that a fifth yet undiscovered force may exist in the universe The experiment is designed to detect and measure possible variations in the gravity constant over distances in excess of 300 feet
181. heck for correct place trouble there are many ready made cabinets on the market ment of components wires and for solder bridges etc nandi o SN PA T 5 3 4 5 Fig 4 If you decide to build the project on a printed circuit board use this pattern Note that for space reasons the board is shown here at half its actual size R1 R2 R3 R4 S NJ e Ld hs d Du gt e 2 ME Then and only then connect a regulated five volt supply to the circuit If all is well the circuit will say Okay indicat ing that it is ready to receive data The circuit will say Okay every time you power up or hit the reset button If you get no response what can say You did something wrong Go back and re check your work and correct the mistake If the voice does say Okay then congratulations you did well Finishing Touches The cabinet shown in the photos 15 of course optional However it does make a nice enclosure for the project should you choose to build the PC board version used aluminum sheet metal and built it from scratch If you are not so ambitious you may choose to enclose the project in one of the many commercially available cabinets Whatever cabinet you choose to use be sure that you select one that is large enough to accommodate your board and the off board panel
182. here Now take a look at Fig 2B A load R is now connected to the voltage source That of course causes current to flow through the load and the internal resistance The current through the internal battery resistance will produce a voltage drop across it denoted V The voltage drop when added to the load voltage will equal Vs just as Kirchhoff s law says The voltage across the internal resistance will of course take away from the voltage that appears across the load The best way to see that is to take an example Fig 2 in an unloaded state A the voltage source can be treated as though its internal resistance does not exist When a load is applied B the resistance becomes noticeable Suppose that we have a 12 volt battery with an internal impedance of ohm Then suppose we connect 5 ohm load to the circuit We know that the total circuit resistance Ry is the sum of the individual resistors in this case the 5 ohm load resistance plus the l ohm internal resistance for a total of 6 ohms Rr Rs R 1 5 6 ohms We now use Ohm s law to find what the current is 12 6 2 We know that the total circuit current now is 2 amperes find out what the voltage across the load is we again use Ohm s law Remember that the voltage is simply the current multiplied by the resistance The load voltage is V IXR 2 5 10 volts Well you can see that the voltage across the load is not the
183. hhoff s voltage law lor series circuits states The sum of the voltage drops across components in a series circuit is equal to the source voltage Fig A that can be written mathematically as Vs Vi V4 V4 where V is the source or applied voltage and V and V 58V Vo 6 5V pom V4 2 3V pm Fig A Kirchhoff s voltage law for series circuits simply states that the input voltage must equal the sum of the voltage drops That means no voltage leaks out referred to as the output impedance of the voltage source The whole idea of most circuit theorems is to attempt to simplify the larger more complex electronic circuits and convert them so they can be represented by a simple circuit like those given in Fig 1 In most cases all circuits can be reduced to the equivalent of a voltage source in series with its internal resistance and the load That is in fact the whole purpose of Thevenin s theorem By using Thevenin s theorem along with the usual Ohm s and Kirchhoff s laws you can easily reduce most circuits into a Thevenin s equivalent which is essentially a voltage source in series with its internal resistance and a load But before we talk in detail about the Thevenin s theorem process let s get a little more familiar with voltage sources In electronic circuit design engineers strive to achieve what is known as an ideal voltage source An ideal voltage source is some component or circuit that suppli
184. hot All board components should operate without undue heating Now check out the 0 5 volt motor source Measure the 9 25V J2 J3 O 12V J4 11 27 3 47 le 1 27 15 32 1 127 1 Fig 6 Although mounting of the panel components is not critical the fixed voltages are at the top and the voltage monitor and variable voltage jacks are at the bottom ad 80X MONT TOR 5 MOTOR gt gt 1 DIS C h p The constant voltage portion can test the various motors found in cassette 8 track and auto cassette players while the 0 5 voltage source can check motors in portable cassettes CD players camcorders and the like voltage at the voltage monitor jacks Slowly rotate R4 and note the change in output voltage Flip S1 and the voltage polarity should reverse Switch 51 reverses the voltage polar ity for testing the small motors found in camcorders cassette players and compact disc players Remember that voltage will drop when a motor loads the supply Checking Cassette Motors Small motors come in different sizes and shapes Most of the motors have two terminal wires but some have three In a three wire motor hookup their is a black wire used as a ground wire Some motors of either type can change direc tion by having their voltage polarity reversed Two small mounting screws usually hold the m
185. hten As I mentioned at the time it was too Here is how the set looked when as this month s restoration work was started Note the stretched grid wire and pinched shield can on the tube behind the power transformer _ m Using vacuum cleaner helped remove spider webs and other accumulated debris from the tight spaces underneath the chassis Once that was done it was time to get down to the serious troubleshooting replaced by its much shorter metal equivalent The top mounted electrolytic con densers capacitors were both Aerovox replacements rather than originals And the universal mounting bracket on one of them had become bent out of shape leaving the capacitor to hang by its wires Finally part of the tone control selector switch a multiple contact waf er type was broken off But was re lieved to see that the missing part of the wafer had carried only unused contacts so operation would be unaffected Remounting the loosened elec trolytic capacitor was an easy job It had been held in place by a simple screw attached bar that extended across the mounting hole The bar had been bent out of shape but was easily removed straightened in a vise and replaced With the electrolytic standing straight and firm again turned my attention to the problem of the tube shield Luckily 1 happened to have a good G type 6A8 in my tube collection With that substituted for the metal ver sion there was
186. ibed Table 1 Make the grille frame from it by stapling it together with heavy duty staples using Fig 4 as a guide Spray the frame s front surface flat black and drape the grille cloth around the frame Wrap the cloth around the lattice work and attach it with staples to back side of the grille Put the grille in place and if any part of the speaker panel shows through the grille cloth darken it with stain or black paint Finish all the external wood surfaces before installing your speakers or crossover network Crossover Network If you apply the usual formulas to the values shown in the schematic diagram of the crossover network in Fig 5 you will notice some variation from common practice The values PARTS LIST FOR ONE TOWER SPEAKER CAPACITORS All capacitors are nonpolarized and rated at 100 WVDC see text C1 C3 4 74 F C2 124F C4 50uF C5 24uF RESISTORS R1 5 2 ohm 25 watt R2 8 ohm 25 watt R3 8 ohm L pad INDUCTORS L1 0 26 mH coil L2 1 mH coil L3 20 51 mH coil ADDITIONAL PARTS AND MATERIALS SPKR1 Audax HD 100 D 25 SPKH2 Precision TX 205 F B Terminal blocks wood supplies and 2 in PVC tub ing see Table 1 for materials and quantities poly ester knit grille cloth 12 in x 40 in wood glue Liquid Nails silicone rubber sealer foam backed carpeting lamp cord 18 or heavier 3 doz 8 x 1Va in wood screws for glue blocks 6 e in T nuts 63 round head bo
187. ic 5 7 470 35WVDC electrolytic ADDITIONAL PARTS AND MATERIALS J1 J8 Banana jack NE1 120 VAC neon lamp R1 1000 ohm 1 or 5 watt wire wound potentiometer S1 DPDT toggle switch T1 18 volt secondary 2 amp power transformer Deluxe case approximately 7 5 4 33 x 2 22 3 heat sinks for TO220 cases AC cord flexible test leads hookup wire PC board bolts and nuts solder etc Fig 4 This foil trace pattern if used oroperly will beautify the circuit layout of the box and simplify wiring Fig 5 Here is the parts placement layout of the etched circuit board Cut the copper clad board from a large piece if you do not have the correct size board Ld 4 INCHES PLI J6 0 5 sO ne MONITOR BO JACKS YEL and the center tap to the solder pad marked BLACK in Fig 5 Do not mount the etched board until all wiring has been completed Wrap the wires around the body of a pencil to take up the slack Tie a 4 inch length of hookup wire to each tie point that connects components on the front panel to the board You may want to mark the voltage sources on top of the PC board to identify where the Connecting wire goes Preparing the Top Panel Drill all mounting holes through the top panel as shown in Fig 6 Clean off any burrs with a pocket or hobby knife The various fixed voltage jacks red and the common jack black were located near the top of the front panel while the 0
188. ics Some will deal with electronics basics some will deal with discrete components some will deal with IC s and some will deal with circuits and applications All will contain the type of information electronics hob byists need but sometimes must search to find With FactCards you can find that information in a hurry gusce m qmm tm gt LINEAR RAMP MONOSTABLE USING 555 TYPE TIMING OELAYEO PULSE GENERATION 15V OIAGRAM o L BUT osi TIMING OIAGRAM IN Olu 1 INPUT U TRIGGER l Vc OUTPUT CONTROL VOLTAGE e FOR V OF 15 T 11 3 4 OUTPUT 2 2 E 911856 AS SHOWN 10 MS 1005 SER PAR SER FEATURES CONT Wide supply voltage range 3 0V to 15V 8 High noise immuntity 9O0 45 Vop typ 8 Low power TTL compatibility fan out of 2 driving 74L or 1 IN driving 74LS IN Q6 5V 10V 15V parametric ratings a Symmetrical output characteristics 1 2 Maximum input leakage 1 pA at 15V over full temperature TRUTH TABLE ange PARALLEL ABSOLUTE MAXIMUM RATINGS SERIAL SERIAL Supply Voltage 0 5 to 18V INPUT CONTROL PL 1 PL Vin Input Voltage 0 510 0 5V Ts Storage Temperature Range 65 C to 150 C a n 0 Package Dissipation 500 mW 0 T Lead Temperature Soldering 10 sec 260 C RECOMMENDED OPERATING CONDITIONS Voo
189. ike a miniature radar detector the item s manufacturer Express Yourself Inc 1800 A Associates Ln Charlotte NC 28217 has decided to go upscale with a Desk Top Office Revenger Mounted on a weighted swivel base and newly equipped with sight crosshair and snub nose barrel the office model offers the original Revenger sound effects machine gun burst grenade launcher and death ray noise According to Express Yourself Inc no boardroom manager s desk or reception area is complete without Price 25 CIRCLE 65 ON FREE INFORMATION CARD Citizen Portable Fax Machine Facsimile transmission has grown enormously in just the past 18 months With an eye toward that expansion CBM America Corp 2999 Overland Ave Los Angeles CA 90064 has introduced a new modular portable facsimile machine that can do double duty as a copier The Cirizen CBM Fax weighs a mere five pounds and operates with its own internal rechargeable batteries or it can draw power from a 12 volt vehicle battery or any domestic or foreign AC power source Transmission speed is less than a minute CBM plans to offer a range of optional accessories beginning with an answering machine that will receive either a message or a fax The CBM Fax features fine or normal resolution half tones auto contrast control automatic or answer mode and can handle standard letter sized sheets The unit comes with a separate power transformer line connection cables and a roll o
190. in MIDI ports Casio CZ101 digital synthesizer with advanced MIDI capabilities and ingenious MIDI software that links computer key board to synthesizer keyboard all yours to train with and keep This year over 1 5 billion worth of digital elec tronic music instruments keyboards guitars drum machines and related equipment will be sold in the U S alone Who s buying this new tech equipment Not just progressive musicians and pro fessional recording technicians but also thousands of people who have never touched a musical instru ment before And there s good reason why Something called MIDI Musical Instrument Digital Interface has suddenly transformed musical instruments into the ultimate computer peripherals and opened up a whole new world of opportunity for the person who knows how to use program and service this extraordinary new digital equipment Now NRI s breakthrough Electronic Music Technology course puts you at the forefront of this booming new technology with exclusive hands on training built around a MIDI equipped computer MIDI synthesizer and MIDI software you keep Dynamic New Technology Opens Up New Career Opportunities for You The opportunities are unlimited for the person who s trained to take advantage of today s elec tronic music phenomenon Now you can prepare for a high paying career as a studio technician sound engineer recording engineer or road technician even s
191. in shielded ca bles used for composite monitors Power is supplied through a small lead protrud ing from the Grayscaler s case The lead has a small connector on the free end which can be clipped to one of the ac cessorvilight pen pin terminals usually provided at the rear of a color graphics card the pin that supplies 5 volts to a light pen The lead can be snaked into the cabinet through any convenient opening just make certain that you connect it to the correct pin Pin 5 is the one that you want unfortunately the pins aren t usually la beled However pin 2 is usually cut short to serve as a polarizing device for the light pen connector So if you know which pin is number 2 you know which are numbers 3 4 and 5 As a general rule pin 5 is towards the bottom of the card pin is near the top but the arrange ment isn t standard some cards have pin 5 near the top No Adjustments The Grayscaler works without need for adjustments utilities or programming tricks Simply plug it in to your comput er s RGB port connect the phono jack to your composite monitor and run your software exactly as it was intended to be run More often than not the screen dis play will probably appear exactly the same as when you ran the monitor from the computer s color composite output You will notice a difference only when running software that creates a graphics display Then the Grayscaler will provide a usable display The Grays
192. ince and R are equal the equivalent is 180 2 90 ohms Find the total current 5 10 90 111A Compute the current in R3 I I V4 R2 R3 10 180 0555 A R3 12082 R 2002 R2 602 1 1800 SHORTED R 2002 C Fig 17 When you redrew the circuit for various stages of the analysis they should have looked like these Calculate the output voltage across R3 V 1 R3 0555 120 6 67 volts V ih VS 67 volts Calculate the Thevenin s equivalent resistance Short That shorts out RI and puts R2 and R3 in parallel See Fig 17B the resistance of R2 and R3 in parallel is 4 R2 R3 R2 a 60 120 60 120 7200 180 40 ohms d The equivalent circuit is shown in Fig 17C 2 Refer to Fig 18 a Remove the load resistance R b Calculate the Thevenin s equivalent voltage across R4 and terminals To do that first find the total circuit resis tance R3 and R4 are in series so their total resistance 15 150 150 300 ohms That appears in parallel with R2 Two 300 ohm resistances in parallel produce 300 2 2150 ohms That is in series with RI to produce a total of 150 100 2 250 ohms Calculate the circuit current with Ohm s law 1 2 V4 R 25 250 1 R1 1002 1502 A R15 1002 R3 1502 A B Vs SHORTED Th 42 860 Fig 18 you didn t get this problem right it is strongly recomm
193. inds are included USING THE CA3130 5 00 50 different ways to put this op amp to work in cluding audio RF test equipment household and miscellaneous projects 4 BP44 IC 555 PROJ ECTS 5 95 Included are basic and general timer circuits automobile and model railroad Circuits alarms and noise makers as well as a section on 556 558 and 559 timers 4224 50 CMOS IC PROJECTS 5 25 These 5 are suitable for an extraordinary range applications This book shows you just how much you can do with them 4 59 2 0 BOOK CMOS PROJECTS 5 50 Still more ways to use these versatile devices None of these projects over lap those book 224 The pair make a wondertul circuit reference set BP84 DIGITAL IC gt PROJECTS 5 50 Both simpie and more ad vanced projects to help the reader develop a knowl edge of the workings of digi tal circuits A number of board layouts are included ee cee ee ee ee es es es es ss es es es ss ss oe MAIL TO Electronic Technology Today Inc P O Box 240 Massapequa Park NY 11762 0240 SHIPPING CHARGES IN USA AND CANADA 0 01 to 5 00 81 25 30 01 to 40 00 5 00 j 5 01 to 10 00 2 00 40 01 to 50 00 6 00 10 01 to 20 00 3 00 50 01 and above 7 50 20 01 to 30 00 4 00 SORRY No orders accepted outside of USA and Can
194. ing to Hama Those machines for reasons having to do with trade regulations are outfitted with a chip that defeats the Video Cut 20 s numbering functions in any but the record mode Or so it was explained to GIZMO The Cut 20 has twice the mem ory capacity as the 10 100 scenes as posed to 50 Also introduced with the Cuts 10 and 20 is a titlemaker the Script 50 1 050 Its most user friendly feature is its computer style keyboard for letter color and effect generation But the Script 50 is another report entirely This trio of European video accessories promises a leap in the level of technology available in home video For the present the editing decks and the title generator would seem custom made for business commercial and video operations like community and school cable or limited range UHF TV station use On the consumer front if the Video Cut 10 really edit the boredom out of home videos its success at just about any price can t come a moment too soon Swiss Miss SWISSTEL TELEPHONE Manufac tured by Swisstel Inc 300 1 c Route 17 Lodi NJ 07644 Price 89 95 In the never ending quest to advance the telephone from a simple tool of communi cation to an electronic era human organ new phones hit the market on a near monthly basis Mermaid telephones car toon character telephones telephones with radios and even telephones with tele visions from the perspective of either low com
195. ing charge Make checks payable to Gernsback Publications Inc M M versatility That allows the ground rod to accept a number of different experimental items Checking It Out Before we start this stage of con struction a word of warning is in order Do not touch or make any adjust ments while power is applied to the Solid State Tesla Coil Remember that you ll be dealing with high volt ages so caution is the watchword With the power off set the spark gap for a s inch gap and connect the tap clip to turn 15 or 16 Plug in the power cord and turn SI on A loud electrical discharge should be heard and a blue brush discharge should be seen at the top of the pointed screw that s con nected to L2 Turn the power off and move the tap wire that s connected to L1 up or down one turn at a time until the greatest blue discharge is obtained at the top of L2 Form a 1 to a 2 inch vertical gap be tween the ground rod and the top of the coil to aid in tuning up the coil When the Tesla coil is properly adjusted it should produce a 2 inch arc between the top of L2 and the ground terminal The coil discharge is most dramatic in a darkened room and you should be able to light a fluorescent lamp at a distance of about two feet from the sec ondary coil A clear incandescent lamp moved to within a few inches of the secondary coil will produce a beautiful blue lightning array from th
196. inize the circuit A TES LOAO REMOVEO T l Vs 8 aim REPLACED 8 R 330 BY A SHORT LOAD OISCONNECTED Fig 8 The first step in Theveninizing a circuit is to analyze the circuit without the load A to find the voltage Next you must short the voltage source s to determine the thevenin equivalent impedance Finally you replace the load but now connected to the equivalent 8861 H38O100 Thevenin s equivalent voltage V Vinc VAR To compute the Thevenin s equivalent voltage between points A and you can use the simple voltage divider formula given earlier We can express that as follows Van V4RIARI R2 Using the values in Fig 8 the Thevenin s equivalent volt age then is Vin 15 30 20 30 15 30 50 15 6 9 volts Fig 9 This is the complete Thevenin s equivalent of Fig 7 The load is reconnected to terminals and B Using Ohm s and Kirchhoff s laws the equivalent circuit will produce exactly the same output voltage values The equivalent voltage source for the circuit then is a 9 volt battery Next we need to compute the Thevenin s equivalent resis tance Again that is done by assuming that the load resis tance 1s disconnected It also assumes that the voltage source is replaced by a short circuit That condition is illustrated in R1 1002 Fig 8B With the voltage source shorted you simply calcu late the total equivalent res
197. ion of both Kirchhoff s and Ohm s laws You know that the generator produces 6 volts output under open circuit condition With the load connected you get 4 volts at the output terminals From Kirchhoff s law then you know that the voltage dropped across the internal impedance V is the difference between those two voltages VS tV V i 6 4 2 volts Knowing that 2 volts is dropped across the internal resis tance and knowing that the current flowing through it is 04 EE Fig 4 The internal impedance of source be determined by making a few measurements and using Ohms law Fig 5 4A quick technique for measuring the output impedance of any device can be performed using a potentiometer and by taking two measurements amperes the source impedance can be calculated as follows Rs 2 04 50 ohms Another method of measuring the internal resistance or output impedance of a voltage source is to use the technique illustrated in Fig 5 It is called the half voltage method Use the procedure described below 1 Estimate the value of the output impedance lt Let s assume that you guess that is near 600 ohms 2 Select a variable resistor whose value is larger than the estimated value For example you may choose a potentiome ter with a value of 1000 ohms In general you may want to make the resistance larger just in case the actual output impedance is larger You might choose a 2 5K
198. ip indi vidual modules are changed as needed The UL listed Dragon handles 6 000 volts in one billionth of a second and is rated at 1 800 watts The basic Dragon CIRCLE 88 ON FREE INFORMATION CARD models with 2 to 4 sockets cost 79 95 to 89 95 The 6 to 16 socket models come with a remote cord and cost from 109 95 to 149 95 Replacement mod ules cost 5 00 each For more infor mation contact Ultima Electronics In ternational Lid 75 Bi County Blvd Farmingdale NY 11735 Tel 800 777 8743 Remote Channel Selection on CB Radio Midland International s Model 77 158 professional class citizens band radio features the Mic ro Tune remote channel selection system With two speed up and down buttons on top of the microphone channel selection is safe and convenient Additional channel selection buttons are located on the radio s front panel giving the user a choice of standard or remote tuning ETR frequency control with a microprocessor chip PLL sys CIRCLE 89 ON FREE INFORMATION CARD tem locks the receiver and transmitter on the desired frequency and adjusts for temperature and humidity to main tain precise tuning The Model 77 158 has RF gain con trol highway and local to adjust re ceiver sensitivity and prevent overload from nearby stations Fully variable mi crophone gain control allows max imum range for audio transmissions Pulse noise from the engine and motor operated devices is reduce
199. ires a minimum of knowledge and attention in short it s vir tually foolproof In fact in the 8 mm for mat even fools can have some fun Getting Personal Whatever doubts remain about 8 mm video Sony Corporation appears to have full confidence in the format At the Con sumer Electronics Show this past summer in Chicago the company unveiled a new line of 8 mm products that it hopes will do for video what the famed Walkman has done for portable audio The concept is personal video and the most intriguing of the three products introduced under that heading is the Video Walkman GV 8 which should be on the market by the time your read this or short ly thereafter About the size of a hard bound book five inches wide two and a halt inches deep and eight inches high the Video Walkman is a battery powered handheld TV VCR combination with re 8mm Video Walkman cording time shift and playback ca pability In the extended mode the 8mm cassette can provide up to four hours of either record or playback time Weighing about two and a half pounds the GV 8 operates from either AC or DC power or from rechargeable nickel cadmium or alkaline batteries when used Mini CCD Camera 8mm Desk Top Monitor VCR Fisher Hi Fi To Go Portable Audio Unit Among other things we wish the consumer electronics industry would stan dardize is a universal name for the portable audio systems that have proliferated during this decade
200. is the display provided by a conventional monochrome composite monitor The right side is how the display appears on the same com posite monitor after processing by a spe cial RGB composite processor called a Grayscaler A Grayscaler is a device that converts a computer s RGB output into an RGB compatible composite signal gen erating a specific brightness level for each of the 16 conventional colors How it Works The conventional composite computer Output is the same kind of analog signal as used tor TV broadcasting and closed cir cuit television Both the monochrome and color information are integrated within the signal If the monitor is B amp W black and white the display is monochrorne If the monitor 18 composite color the dis play is in color Since the signal contains both monochrome and color elements it is called a composite color signal RGB color is something else The red blue green and intensity hue signals are independent digital outputs that are integrated into a color display within the This is a photo of a screen display showing how a graphics display appears on a composite monitor left side and how it appears on the same monitor 4 atter processing by the Grayscaler right side monitor itself The horizontal and vertical sync signals are also independent If the computer software controls each of the color elements as an independent signal source it is unlikely they be inter pret
201. is worse than realizing that you don t have enough wire to finish the job when it s too late to do anything about it Begin the electromagnet by threading a few inches of wire through one of the off center holes in the washer That helps keep the windings from becoming undone The windings needn t be perfectly even but do your best Give yourself plenty of time to wind the coil it may take a while When you re done the windings should be tight enough to hold the metal strip firmly against the head of the screw and the fiber washer against the nut Terminate the winding in the way you began by threading a few inches of wire through one of the off center holes as shown in Photo 1 The leads coming off the coil should be long enough to work with easily once the assembly is mounted The Cabinet The cabinet be made of wood or plastic The top or what will be the top of the box should be no more than about 4 inch thick Very heavy material may put too much distance between the electromagnet and top surface of the cabinet The case in the photos is a wooden knick knack box painted black the top of which is about 14 inch thick Also do not choose a cabinet that is too small The unit heats up very rapidly and the components need as much air around them as possible Now 15 the time to decide how you will mount the coil bracket inside the box you have chosen to use The important part is to make sure the end of the electromagnet fits ti
202. istance between terminals and Vs 6V vr 9 A B In this case the 20 and 30 ohm resistors are simply in parallel with one another and so the equivalent resistance can R2 1000 Ri be computed by using the standard parallel resistance for B mula The total resistance is M EM R4 RIR24RI R2 20 30 204 30 600 50 12 ohms The total resistance therefore is the Thevenin s equivalent R1 1000 resistance R R3 250 A Rin R Vg WA O We can now draw the complete Thevenin s equivalent 9 3 3 ue 8 which is illustrated in Fig 9 lt is simply a 9 volt battery in series with a 12 ohm resistor The load is reconnected to MUR terminals and B Now using Ohm s and Kirchhoff s laws um REMOVED for additional calculations the equivalent circuit which is easier to work with will produce exactly the same output voltage for varying load values as the original circuit The load voltage V between and B is found as follows EE First calculate the total circuit resistance O R R R 1002 Roy 7582 R4 51232 45 ohms m See Next find the current 1 HAT V Rp 9 45 2 Fig 10 We wish to compute the Thevenin s equivalent voltage and resistance of the circuit in A Begin by The load voltage V then is removing the load B and calculating the output voltage Note that we are using an AC generator V I X
203. it must because there s no stand or cradle to rest it on Instead a back mounted retrac table hook allows it to hang We d be care ful about leaving the petite telephone on the floor its small size and light weight make it especially susceptible to being stepped on or kicked around Instead of a cradle stand Swisstel offers an accessories package at 9 95 includ ing a wall mount phone hook the hook a removable over sized hook that attaches to the phone skid stoppers which look suspiciously like color coordi nated rubber bands but which promise to end dangerous skidding when you put the ND ee Gizmo is published by Gernsback Publications Inc 500 B Bi County Blvd Farmingdale NY 11735 Senior Writer George Arthur Contributors to ay abit See E E phone down an earpiece cover provides a cushion for your ear and much needed shoulder cradle The last item lets the user prop the phone between shoulder and ear without it long conversations could necessitate a visit to the local chi ropractor Which brings us to another shortcoming that the compact chatterbox displayed dur ing Our test The Swisstel at least for an adult is just not a comfortable telephone Clever in design and execution but not a phone to lean into for those long chats Its light weight makes it feel too much like a toy while its audio quality had us con stantly fiddling with the earpi
204. it hasn t done the belly flop foreseen by some skep observers of the video market Instead the 8 mm format seems to have staked its claim to a chunk of the corder market ts small size as ex empiified in Sonv s CCD V5 Video Cam era Recorder 8 handycam has been an important factor in the format s accep tance The 8 mm videocam seems to be the camcorder of choice for many movie fans for just that reason The CCD VS5 trom Sony certainly seems representative of 8 mm s virtues The compact 3 pound 5 without battery unit offers recording capability playback and an autofocus system that can make videotaping as easy as taking snapshots The 8 mm video s cassette with a 120 minute capacity is just about the size of an audio tape In a nice rcfine ment the cassettes also feature a sliding crase protection tab Power for the unit comes from the usual trio of sources standard household current with the supplied AC pack battery charger ACP 88 a rechargeable battery 52 Page 6 GIZMO CIRCLE 54 ON FREE INFORMATION CARD NP 22 good for one hour of continuous operation when fully charged and an op vehicle cigarette lighter and DC pack DCC 16AW DCP 80 respectively for drawing power from a 12 6 volt auto motive battery There s also a lithium bat tery mounted in the unit s bottom to activate the CCD V5 clock and title mem ory functions Ease of Operation t
205. ive operator guid ance displays that indicate where problem or glitch might be originating Still it seems to us that the Video Cut 10 might not be the first accessory a novice would want to add to a home video arse nal In demonstration the Video Cut 10 was a compact marvel of precision and memory a smaller sibling to the profes sional equipment used in the television industry and related fields But even in a highly controlled run through the potential for operator con fusion was clear The rather verbose Ger man to English translated instructions aren t likely to clarify much at least in their draft version If someone knows the German term for troubleshooting sec tion they should suggest it to the man ufacturer The companion Video Cut 20 which is capable of transferring from VHS cassette as well as 8 mm video has a suggested retail price of 2 200 which is substan tially higher than its 8 mm counterpart For the most part that reflects the necessity of developing a system for frame number ing that s compatible with the editing units needs and with home video equip ment The solution was a straightforward adaptation of professional video s ver interval time code For editing pur poses the Cut 20 generates its own frame numbers for VHS But frame numbers can only be generated and assigned during re x cording which means that it can t be used with existing VHS camcorders accord
206. land Wichita KS 67214 GET OUT OF THE DARK Open your eyes and see just how many subjects are Covered in the new edition of the Consumer Information Catalog It s free just for the asking and so are nearly of the 200 federal publications described inside Book lets on subjects like financial and career planning eating right exercis ing and staying healthy housing and child care federal benefit programs Just about MP ier would need to know Write today We ll send you the latest edition of the Consumer Informa tion Catalog which is updated and published quarterly It ll be a great help you ll see Just write Consumer Information Center Dept TD Pueblo Colorado 81009 U S General Services Administration ADVERTISING INDEX HANDS ON ELECTRONICS magazine does not assume any responsibility for errors that may appear in the index below Free Information No Page 6 AMC 259 22 Ace Communications 103 5 All Electronics 13 Amazing Desices 27 Antique Electronic Supply 104 8 e S uen 11 19 25 Command Productions 103 10 Cook s 101 11 Digi Key CV2 23 Electronic Parts Outlet 93 Electronic Tech Today X 14 28 Electronic Tech Today 100 Electronics Book Club 3 20 2222220 95 2
207. lity is no problem In addition they come with a program that allows ballistic gain control a concept that MacIntosh users are familiar with With ballistic gain control motion sensitivity 15 adjusted on the fly as you use the device For example moving slowly you might have to move four inches to move the mouse pointer across the screen Moving the mouse quickly however might require only two inches of motion Sensitivity is adjustable through software The advantage of ballistic gain control is that for precise operations editing pixels bit by bit for example you want maximum accuracy But to activate a menu and save your file speed iS most important FastTRAP stands for Fast Axis Pointer as you can see in the photo the device differs from the PC Trac through the addition of an additional vertically oriented wheel called a trackwheel that allows operation in the third Z axis in 3 D CAD programs In addition the trackwheel can easily be configured for use in spreadsheets and word processors In that case rotating the wheel would simulate pressing the PGDN and PGUP keys or any other keys that are convenient for your application The PDA Pointing Device Adapter is a half length card that plugs into an 8 bit slot The PDA does two things it allows you to convert just about any serial mouse into a bus mouse thereby saving you a serial port and it brings bal listic gain control to mice that don t have the ca
208. lly OPPORTUNITY WITHOUT RISK The biggest improvement in 40 years has made U S Savings Bonds an ideal investment A variable interest rate lets you share in rates offered by today s securities market No limit on how much you might earn What makes this improved Bond ideal is that you re protected by a guaranteed minimum And if the Bond is held to maturity you ll double your money Take another look at this opportunity without risk SACS in America A public service of this publication and The Advertising Council Serre THYRISTORS 2 HEADPHONE gt INTERFACE POLARITY TESTER RAD HOUND DS iF YOU RE THE KIND OF READER that doesn t want to wait you can order your next copy of Hands on Electronics now Hands on Electronics is crammed full of electronic proj ects that you won t be able to wait to build for yourself You can expect top notch digital proj ects fun to play electronic games valuable add on computer projects BCB and shortwave receivers photographic darkroom gadgets de vices to improve your cars performance test equipment ideas and more in every issue of Hands on Electronics YOU CAN HAVE THE NEXT TWELVE 15 SUES of Hands on Electronics delivered to your home for only 18 95 saving 11 05 off the single copy price EVERY ISSUE OF Hands on Electronics will continue to contain a variety of constructio
209. load resistance R as a voltage divider It can be more easily seen if we redraw the circuit as shown in Fig 3 A voltage divider is simply two or more resistors that are used to develop an output voltage somewhat lower than the input voltage Normally we design voltage dividers by choosing two resistor values that will give a desired output voltage for a given input voltage The basic formula used for figuring the output voltage of a voltage divider given the resistor values and the source voltage is Vo VgsR Rg Ry Here is the output voltage across the load Vg is the open circuit source voltage R is the load resistance and Rg is the internal resistance of the voltage source As an example of the use of the formula let s use the 12 volt battery we assumed before but this time assume it has an internal impedance of 0 1 ohm instead of ohm The load resistance IS still 5 ohms The voltage across the load in that case then would be Vo 7 12 5 5 0 1 12 98 11 76 volts Here you can see that when the internal resistance is only a tenth of an ohm instead of 1 ohm the output voltage is 11 76 volts or very much closer to the source voltage than the 10 volts produced with an internal impedance of ohm Now you can see why it is desirable to keep the internal impedance low Fig 3 The source s internal resistance and the external load form a voltage divider making the output voltage of the source easy to determin
210. lts nails 1 a in long 5 yd of 1 in thick acoustical Fiberglas asphalt roofing pieces Speakers and crossover components are available from McGee Radio Co 1901 McGee St Kansas City MO 64108 Radio Shack sells a package containing 1 yd 1 in thick acoustical Fiberglas enough for both en closures 886 H38O0120 a HANDS ON ELECTRONICS A 38 7 16 1 1 8 Fig 4 The dimensions this drawing of the speaker grille are all given in inches The lattice work pieces are lettered to correspond to those in Table 1 shown in the diagram were selected after testing the system rather than by formula alone The Parts List specifies ordinary non polarized electrolytic capacitors which work well Some speaker design engineers insist Mylar or polypropylene speaker capacitors par in the tweeter circuit If you decide to substitute the more expensive Mylar or polypropylene units you should change the values of and C2 because the typical non polarized capacitor runs lower than its polarized counterpart To make the change reduce the value of CI to 4uF and the value of C2 to 10 In setting up the crossover network don t install the vari ous coils too close to each other If you must place one within a couple of inches of another coil set the two at right angles to each other And keep them away from pieces of iron or steel You can
211. ludes re versible ratchet handle ex tension bar six bits two precision screwdrivers and a cutter Comes in fitted case Get one for your shop another for your car an other for your tool kit O TOOL KIT NINE PIECE TOOL KIT 9 50 Includes saw bub ble levet three screw drivers torque multipier calipers for inside and out side measurements nip pers and a tape measure O BP233 ELECTRONIC HOBBYISTS HANDBOOK 9 95 Provides inex pensive single source of easily located data that the electronics enthusiast is day hobby activiites 8 x 10 inches 1 BP232 CONCISE IN TRODUCTION TO MS DOS 5 95 If you are a PC user and want to get the most out of your computer you must learn its MS PC DOS operating system That s what thus book shows you Modern Dpto Device Propecis NS BP194 MODERN OPTO DEVICE PROJ ECTS 6 25 Provides a number of practical designs that use opto electronic de vices such as fiber optics LED s and passive de tectors BP234 TRANSISTOR SELECTOR GUIDE 10 00 Prepared from a vast database specifica tions Unique guide offers a wide range of selection ta bles More than 1400 de vices are listed along with Specs MAIL TO Electronic Technology Today Inc 0 Box 240 Massapequa Park 11762 0240 SHIPPING CHARGES IN USA AND CANADA 0 01 to 5 00 1 25 30 01 to 40 00 5
212. m message length proportionately Playback is essentially the reverse process The RAM memories are strobed to output the stored bits of au dio information in the sequence in which they were stored The main chip IC3 detects those bits and converts them into an analog audio signal that can be amplified by IC4 and heard from the loudspeaker Assembling the Board The Digital Voice Record Playback Module comes complete with the PC board and all of the parts that mount on it See the Parts List The builder sup plies only the power supply or battery cabinet wire miniature loudspeaker and switches Putting together a printed circuit board with all the parts supplied in kit form is the simplest approach to tack ling a project especially when the parts side of the board is silk screened to identify the parts locations Aside from the soldering errors that can plague any construction project about the only thing that can go wrong is the misorien tation of the integrated circuits or the 8861 H3HOLOO o ON ELECTRONICS o HANDS C1 RV2 REC VOLUME 33pF LD1 A 10K R12 S4 56 SLOW Twice 3900 51 53 PLAY STOP PL ST A3 R2 100K 100K R4 100K 100K F1 SA 9V0C ClO 701 LE 100 RECORD R13 1 5MEG gt R9 2 7K ffi e C Fig 1 complete schematic diagram for the Digital Voice Record Pl
213. mportant principles of antique radio repair Don t get serious about troubleshooting your radio until you ve thoroughly cleaned and carefully examined it to uncover any components that have ob viously failed checked for any sloppy or incorrect repairs or for any parts that were incorrectly installed by the pre vious owner s Although it wasn t a problem with this particular set the tube types should also be checked against the tube loca tion chart to make sure that the correct type is in each socket If your set doesn t have a tube chart and you haven t been able to obtain service notes remove each tube and look at the socket The correct tube type may be marked on it Removing and replacing tubes and other plug in components is a good idea for another reason If contact be tween the pins and sockets have become impaired through oxidation and corro sion the act of removal and replace ment may reestablish it So by applying a little elbow grease to the set and by using your powers of observation and a little common sense you can take care of many problems that might otherwise be difficult to isolate and resolve Until Next We Meet That s about all the space allotted to us this time around But be sure to join us next month when we ll continue the Zenith restoration saga Until then please continue to send me your com ments questions and stories Write to Marc Ellis C O Hands on Elec tronics 500 B Bi County
214. much easier ELECTRONIC CIRCUIT WITH A VOLTAGE SOURCE Fig 6 Any complete circuit A can be replaced by its DC Thevenin B or AC Thevenin equivalent for analysis to analyze Figure 7 shows a DC voltage source connected to a simple two resistor voltage divider A load resistance R is connected across the voltage divider output Typically the problem is to determine the output voltage across terminals A and B or Vag for different values of load resistance Of course you can use standard circuit analysis techniques for computing parallel and series resistance values then use Ohm s and Kirchhoff s laws to compute the value for the output voltage for each load resistance That is a rather time consuming process much easier approach is to simply Theveninize the circuit coming up with a simple voltage source equivalent to which the load is connected With such an arrangement the output voltage for various values of load resistance can be more quickly and easily obtained To Theveninize a circuit the first step is to remove the load resistance as shown in Fig Then use standard Ohm s and Kirchhoff s law procedures to compute the voltage that appears across and B without the load That is called the Fig 7 0Of course you can use techniques for computing parallel and series resistance values and use Ohm s law to compute the output voltage for each load resistance A much easier approach is to simply Theven
215. munications 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 CIE5 Auto Programmed lessons are designed to take you step by step principle by principle You also get valuable hands on experience at ever y stage with sophisticated electronics tools CIE designed for teaching Our 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 toll free phone call away T s 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 school catalog and a complete package of enrollment information For your convenience well try to have a representative contact you to answer your questions 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 cant rsonalized training You learn best with flexible
216. my first official act was to get out the vacuum cleaner to remove the dust debris and cobwebs In areas that were especially dirty the vacuum worked better after the debris was first loosened with a soft brush As 1 scrutinized all of the compo nents for signs of overheating or other failure my eye was almost immediately drawn to a big orange resistor that proved to be the screen dropping re sistor for the 6K7 IF amplifier At some ume in the past the resistor had become so hot that much of its paint had burned off The scorch marks on the chassis above the component also suggested se vere overheating Continued on page 101 8861 H38O100 eo ga By Herb Friedman COMPUTERS on Hi A dual purpose device that backs up protected floppies and more m Si cis RED INN j M e n been available in both IBM and Macin tosh versions and the Macintosh is rapidly becoming a serious contender in the business world While a program written for the won t run on a Macintosh and vice versa the data JWIir H FEW EXCEPTIONS UNTIL RE Actually I often think I see the pro cently software was generally written grams advertised under different names but the distributors always deny any connection to the original Occasionally came across software that could not be copied by COPYIIPC for a specific family of computers IBM Apple Il Macintosh etc N
217. n articles to suit every taste In addition feature articles on electronics fundamentals test equip ment and tools will round out each issue Of course Hands on Electronics will continue to provide new product and literature listings to keep you up to date on the latest developments in electronic technology GET IN ON THE ACTION Order your next issue of Hands on Electronics today Use the convenient order coupon below Be sure to send check or money order no cash oe c UAA 8 c 8 Hands on Electronics SUBSCRIPTION ORDER FORM want to be sure don t miss any issues Send me ONE FULL YEAR twelve issues of Hands on Electronics for 18 95 Canada 23 95 U S Funds Payment Enclosed 1 Bill Me Later Acct 4 Please charge my O Visa O Mastercard Signature Exp Date Allow 6 8 weeks for the first issue to arrive Offer valid in U S Funds Only Please print to HANDS ON Name ELECTRONICS SUBSCRIPTION DEPT P O BOX 338 Street Address MOUNT MORRIS IL 61054 City State Zip AHOK8 Detach and mail today 8861 HAGOLDO HANDS ON ELECTRONICS e 7 C RATCHET ELEVEN PIECE RACHET TOOL KIT 10 00 inc
218. n addition to shortwave Now Radio uses 10 kilowatt Meyer says his ability with languages was one reason he got The Happy Sta assignment He spoke fluent En glish German and French in addition to Dutch when he started After a six week crash course in Spanish he had a handle on that language as well He also responds to listeners in Italian and Swiss German literally his mother tongue since his mother is Swiss born In addition to the two Happy Station airings to North America on Sunday night eight other repeats go out to other parts of the world And there is a Span ish version of the program conducted by Meyer La Estacion de la Alegria which is aired seven times The pro gram covers the entire globe Meyer like Startz before him avoids controversy He says his goal is har mony That according to the program host means harmony in person to CREDITS Kenneth Cobb David Clark ONT Robert Ross ONT Richard D Angelo PA Rowland Archerr NC Mark Cody ONT Tom Gavaras MN Paul Buer FL John To person relationships the starting point ki PA Wally Rh C Ontario DX i world matters poleskt Wally Rhyne NC Ontario lor greater harmony Association Box 161 Station The program is subtitled Your Sun Willowdale Ontario Canada M2N 5S8 day Family Show of Smiles Across the North American SW Association 45 Wild Miles
219. n are the LED and condenser microphone cuit board Do not clip its leads Con nect the longer lead anode to the LDI terminal and the shorter lead cathode to 101 Connect two short wires to the loud speaker and connect those to the 15 and 15 terminals Polarity is not important here reversing the leads will not cause any ill effects Connect two single pole single throw pushbutton switches to the printed circuit board Connect one lead from S1 PLAY to the PL terminal and one lead from S2 RECORD to the RECORD terminal The remaining two leads one each from SI and S2 con nect to the COM terminal Check the connections you just made and the printed circuit board itself When you are satisfied that all of the PARST LIST FOR THE DIGITAL VOICE RECORD PLAYBACK MODULE SEMICONDUCTORS C2 4164 64K x 1 bit DRAM integrated circuit IC3 VLK2653 digital voice integrated circuit IC4 LM386 audio amplifier integrated circuit T1 BC327 NPN transistor ZD1 3 6 volt Zener diode CAPACITORS C1 33 pF ceramic C2 001 4F ceramic C3 0033 yF ceramic C4 01 pF ceramic 5 047 ceramic 6 1 ceramic C7 1 pF 16 WVDC electrolytic C8 10 4F 16 WVDC electrolytic 9 47 16 WVDC electrolytic 10 100 16 WVDC electrolytic C11 220 4F 16 WVDC electrolytic RESISTORS All fixed resistors are 1 4 watt 5 R1 R7 100 00
220. n of modern transistors Japa nese European and American types _ BPS6 ELEC TRONIC SECURITY DEVICES 5 50 Three bask sechon Switch activated alarms infrared amp ultrasonic sys tems smoke gas waler detection 8P65 SINGLE BP59 SECOND BP182 MIDI PROJ 49 BOOK FOR CMOS IC ECTS 6 95 Details PROJECTS e 5 75 ELECTRONIC PROJ PROJECTS 5 50 of how to interface many All projects in thes book ECTS 5 95 A Multhabrators ampihiers Inggers amp gates special devices including reac bon limet simpie eiectroni Organ and Zip are based on one IC and are simple fo construct Great way to get started wilh ICs popular home computers with MIDI music systems Circus tor ihe expen menter CHECK OFF THE BOOKS YOU WANT SHIPPING CHARGES IN USA AND CANADA outside of USA and Canada 0 01 to 5 00 1 25 5 01 to 10 00 2 00 Total price of merchandise 10 01 to 20 00 3 00 Sales Tax New York State Residents only 20 01 to 30 00 4 00 Shipping see chart 30 01 to 40 00 5 00 All amp 40 01 to 550 00 6 00 payments must H10 88 50 01 and above 7 50 be In U S funds BP198 AN INTRO DUCTION TD ANTENNA Basic concepts relevant to receiving and Iransmitting collection of a wide range ol electronic projects and Total Enclosed BP146 THE PRE
221. n our brief test the camera pro duced videos of impressive clarity and consistency Likewise in playback and connected to a television to this reviewer s eyes the CCD V5 performed as well as the big boys of VHS While pre recorded cassettes are not a strength of the format they are out there Sony as well as other 8 mm man ufacturers go to some special efforts to let owners know about currently available and new releases A feature of the CCD V5 that seemed to us a bit fussy a mountain capable of bringing forth a molehill if you will is the unit s titling capability Essentially the feature allows the camera to memorize a title written on a card and then superim pose 1t Over a scene in one of eight colors It s a sophisticated capability but requires three special controls and two pages of directions in the manual Still for the ded icated video enthusiast the title function once mastered not only will make for a more professional program but could backstop the always fallible human memo ry With the title as part of the tape mixing up vacation trips or weddings years after the event will be less likely A feature missing here is any kind of frame count display and that seems unfor tunate We d gladly trade the title ca pability for an accurate tape counter But perhaps the choice was made on the basis of the CCD VS s potentia user This is definitely a home video unit It s fun easy to Operate and requ
222. n weeks of its purchase A drop off the end of a table put an end to its short miserable life Sony is to be commended for replacing it with a hopefully improved model Consider this the TM 1I s obitu ary Though we have not had a chance to personally review the current 21 Pressman Sony s most affordable hand held Cassette Corder features single touch recording cue and audio review dur ing fast forward and rewind auto shut off built in microphone and something called instant edit If our experience with the 11 was representative the TCM 21 should feature a better microphone Our faith in state of the art was renewed by the tremendous performance of the Sony top of the line entry the WM D3 We still recall how miraculous the audio quality of the first Walkman we ever lis tened to seemed at the time WM D3 s performance inspired the same kind of disbelieving astonishment In a variety of crowded noisy nightclubs and open air concert settings that Walkman stereo unit recorded live music from delicate acous tic instruments to high decibel rock and roll with astonishing fidelity After using the WM D3 it s not diffi Vid Bid VIDEO CUT 10 Distributed by Pho to Systems Inc 7200 Huron River Dr Dexter MI 48130 Price 1 249 95 Like eight track audio tape 8 mm and super 8 motion pictures appear to be a technology who s time has come and gone at least on the consumer front
223. nd principles of data communications sys tems in general Opening with a history and overview the book discusses data terminals messages and transmission channels asyn chronous and synchronous modems inter faces digital transmissions fiber optic and satellite communications protocols and er ror control Tips given for setting up a system to communicate between a personal or pro fessional computer and either another per sonal computer a data base Service or an electronic bulletin board Information is in cluded on architectures and packet networks network design and management Integrated Services Digital Network ISDN and the Hayes modem command set Using a text book format each chapter begins with an introduction and concludes with a summary of the material presented and a self quiz Understanding Data Communications Second Edition is available for 17 95 from Howard W Sams amp Company 4300 West 62nd St Indianapolis IN 46268 Tel 800 428 SAMS CIRCLE 95 ON FREE INFORMATION CARD 1988 SHORT FORM CATALOG LEADER INSTRUMENTS CORPORATION This 4 page brochure presents a cross section of Leader s line of more than 100 test and measurement instruments It fea tures oscilloscopes professional video test equipment signal generators audio and video service instruments frequency count COMPUTER CHASSIS with POWER SUPPLY NEW
224. nderstand ing how printers should work the reader will be better able to localize the trouble when they don t work Subsequent chapters contain detailed troubleshooting and repair information for each type of printer Charts schematics and component lists are included The author discusses tools and test equipment solder ingtechniques and guidelines and cautions for making repairs Each part ofthe printer print heads transport mechanisms power systems logic and control systems is dis cussed separately and in relation to other parts This 194 page book also includes a sec tion on preventive maintenance to help read ers prolong the lives of their printers Two useful appendices provide IC pinout dia grams to facilitate the identification of the input output power and ground connec tions for logic IC devices and a listing of printer manufacturers and suppliers Printer Troubleshooting amp Repair No 22543 costs 19 95 It is available from bookstores computer stores and electron ics distributors or from Howard W Sams amp Company 4300 West 62nd St Indianapo lis IN 46268 Tel 800 428 SAMS CIRCLE 95 ON FREE INFORMATION CARD QUATTRO THE PROFESSIONAL SPREADSHEET MADE EASY by Lisa Biow Quattro software offers a combination of spreadsheet database and graphics that is easy to use and is very powerful This 600 page book provides a thorough back ground in the basics of spreadsheet organi za
225. need EIN yourown computer controlled music center to take advantage of today s opportunities in electronic music technology With your experienced NRI instructor always available to help you master the basics of electronic theory step by step gaining the full understanding of electronics that s now so essential for technicians and musicians alike You move on to analyze sound generation techniques digital logic microprocessor fundamentals and sampling and recording tech niques ultimately getting first hand experience with today s explosive new technology as you explore MIDI waveshaping patching sequencing mixing special effects and much more Plus even if you ve never been involved with music before NRI gives vou enough basic training in music theory and musical notation to appreciate the creative potential and far reaching applications of today s electronic music equipment Send Today for Your FREE Catalog For all the details about NRI s innovative new train ing send the coupon today You ll receive a com plete catalog describing NRI s Electronic Music Technology course plus NRI courses in other high tech in demand electronics fields if the coupon is missing write to NRI School of Electronics McGraw Hill Continuing Education Center 3939 Wisconsin Avenue Washington DC 20016 MIFE School of Electronics McGraw Hill Continuing Education Center 3939 Wisconsin Avenue Washington DC 20016 CHECK
226. ng With a small power transformer some magnet wire and a few other parts you can create your own jumping bean simulator in two or three hours MAGINE DOING THE FOLLOWING PLACE SMALL METAL Step One First you need to wind an electromagnet and make mounting bracket Obtain a fairly stiff strip of non ferrous metal about or 74 inch wide The material in the photos is brass but aluminum or copper will work too The length of the strip will depend on the size and shape of the cabinet more on that later Drill a hole in the center of the strip that is just large enough to accommodate a steel screw from your hardware collection The screw should be 1 to 2 inches long If possible use a flathead screw Push the screw through the hole fit a perforated fiber washer onto the opposite end and secure it with a nut You re now ready to make the electromagnet Plan on winding at least 8 or 10 layers of 20 magnet wire around the screw You will need between and pound of wire J t 4 VB INN cM x n a F TR T M a 4 t I LI M a KT cr HN 1 E uon This is a rear view of the electromagnet Note how the leads have been drawn through two of the holes in the perforated washer to prevent the coil from unraveling depending on how large a coil you wish to make so make sure to get enough Nothing
227. nge of optional accessones available Covers 27 54 MHz 108 174 MHz 406 512 MHz and 800 950 MHz 55 Banks and 5 Search Banks 28 Day Satisfaction Guarantee Full Refund if not Satisfied No Frequencies cut out Size 2 x 5 x1V wt 1207 AR900 Tota Price Fresght Prepaid Express Slupping Opnonal COMMUNICATIONS 10101 E 106th St Indpls IN 46256 Toll Free 800 445 7717 Visa and MasterCard COD slightly higher In Indiana 317 849 2570 Collect FAX 317 849 8794 CIRCLE 22 ON FREE INFORMATION CARD BeanFCC LICENSED ELECTRONIC TECHNICIAN Earn upto 30 an hour ja and EN Oy 1 Sh Learn at home in spare time 1 No previous experience needed No costly School No commuting to class The Original Home Study course pre pares you for the FCC Commercial Radio telephone License This valuable license is your ticket to thousands of exciting jobs in Communications RadioTV Micro wave Computers Radar Avonics and morc You don t need a college degree to qualify but you do need an FCC License No Need to Quit Your Job or Go To School This proven course is easy fast and low cost GUARANTEED PASS You get your FCC License or money refunded Send for FREE facts now MAIL COUPON TODAY belio 1 COMMAND PRODUCTIONS 1 FCC LICENSE TRAINING Dept 203 1
228. nics 4 D 115 Hands On Electronics 45 1 1 1 1 see eee we wae 116A Hands On Electronics Jan Feb 86 4 50 O 1168 Hands On Electronics Mar Apr 86 4 50 116 Hands On Electronics May Jun 86 4 50 O 116D Hands On Electronics Jul Aug 86 4 50 116 Hands On Electronics Sep Oct 86 4 50 116K Hands On Electronics Nov 86 1161 Hands On Electronics Dec 86 4 00 117 Hands On Electronics 1987 back issues Write in issues desired 118 Hands On Electronics 1988 back issues Write in issues desired Pc Ir EHE 150 TV Descrambier o O EH87 Experimenters Handbook 152 8 Ball Satellite TV Antenna 108 Radio Electronics 1988 back issues 3 00 Write in issues desired 107 Radio Electronics back issues 1987 3 25 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 ARTICLE 106 Radio Electronics back issues 1986 3 75 Write in issues desired o P 105 Radio Electronics back issues 1985 4 25 Jan 85 not available Write in issues desired 1 amp J
229. nics concepts to life module for tapes all blend together a 15 to give you a Clear simplified understanding of trial examination simply complete the card contemporary electronics and send today If the card is missing write With each module you receive a McGraw to us for ordering information Hill Action Audio Cassette that brings to life the facts and makes you feel as if you re partici pating in a lively dialogue with experts Your ability to quickly make this knowledge your own is further aided by strikingly illustrated texts that use diagrams explanations illustra tions and schematics to drive home and rein McGraw Hill sel Continuing Education Center 3939 Wisconsin Avenue NW Washington DC 20016 experiments reinforce every significant concept 9 8861 at S ON ELECTRONICS o HAND ENSEN JDATING BACK 1928 AND THE EX perimental transmissions of station PCJJ operated by the Philips Laborato ries in Eindhoven Holland Radio Nederland s RN weekly Happy Station show this year celebrates its 60th birthday making it the oldest pro gram on radio Its 25 kilowatt shorn wave transmitter was big stuff in those proneer broadcasting days but it took that kind of lung power to reach the Dutch East Indies half a world away Today s SWLs can hear it even better thanks to the 3
230. no longer any need for the shield can top to be pinched in Straightening out the dent was fairly easy and left only a few visible ripples As it turned out though I didn t have to use the repaired can because 1 also hap pened to have an identical and per fect replacement in my junkbox When working with the shield cans 1 found that they were designed to bay onet lock firmly onto chassis mounted flanges That arrangement guaranteed a good electrical connection between chassis and can However as received those locks were not engaged and the cans were simply held in place by fric tion The lack of good electrical contact could easily explain the oscillations observed during my initial test of the radio Since the top of the set definitely needed a deep cleaning decided there was no time like the present To provide better access I carefully removed all the tubes and tube shields 1 also re moved the metal tuning eye tuning ca pacitor bracket The capacitor was suspended from the bracket by three threaded studs passing through grommet lined holes Besides making it easier to clean the tuning capacitor and surrounding chas The overheated burned resistor was re placed with a new one of the proper value Finding problems like that up front eases troubleshooting later sis the removal of that bracket gave me the opportunity to replace the dried out and hardened shock absorbing rub ber grommets be
231. nt failures by signaling the user with a short beep when a new minimum or maximum value has been recorded The Fluke 87 s analog display which is updated 40 times per second is a high resolution pointer The display can be back lit and has a user selectable 4V5 digit 20 000 count mode in addi tion to its standard 324 4000 count digital display A true RMS multimeter the Fluke 87 also features a peak MIN MAX recording mode with l ms re sponse that is ideal for capturing tran sient events at ED ERE otiosi CIRCLE 40 ON FREE INFORMATION CARD The digital multimeter features a rel ative zero mode has Touch Hold pability which senses a stable reading and locks it on the display tor conve nient viewing after the test leads have M M n lia S s been removed It has 20 kHz AC voltage response and DC accuracy to within 0 1 The Fluke 87 is overload protected to 1000 volts in ohms and diode test It is EMI shielded and is packaged in a splash and dust proof case with a pro tective holster The case s unique flexi ble rubber stand allows the meter to be hung from doors or pipes as well as being used as normal tilt leg The Fluke 87 which carries a three year warranty will be available November Ist for a suggested retail price of 259 00 For further informa contact John Fluke Mfg Co Inc P O Box C9090 Everett WA
232. ntegrated circuit U5 74LS138 decoder integrated circuit U6 74LS04 hex inverter integrated circuit U7 MC1489 RS232 line receiver integrated circuit U8 LM3686 audio amplifier integrated circuit CAPACITORS C1 220 4F electrolytic C2 100 16 WVDC electrolytic 4 10 16 WVDC electrolytic C5 1 pF 16 WVDC electrolytic C6 C9 90 1 4 F Mylar C10 11 022 Mylar C12 100 pF ceramic disc C13 C16 22 pF ceramic disc C17 C20 3 3 pF tantalum RESISTORS All fixed resistors V watt 5 units unless otherwise noted R1 R4 10 000 ohm R5 270 ohm R6 10 ohm R7 100 000 ohm R8 R9 33 000 ohm R10 10 000 ohm linear taper potentiometer ADDITONAL PARTS AND MATERIALS S1 SPST normally open pushbutton switch S2 4 position DIP switch SPKR1 8 ohm speaker XTAL1 10 MHz crystal XTAL2 3 12 MHz crystal Printed circuit board cabinet RS 232 connector 22 or 44 contact card edge connector optional IC sockets power connector wire solder etc 8861 H3EOLDO e HANDS ON ELECTRONICS C R1 R3 10K 10K V 33K 33K R2 C107 C11 R10 10K 0 022 _0 022 10K lt c Ji S2 07 RS 232 1 MC1489 0 IN 2 773 C12 RS 232 SIGNAL O GRDUND m ps c16 22 p p 12 3 12MHz C13 1 V c2 C18 C19 C20 XTAL le 100 3 3 33 33 33 10 00MHz I5 4 CP
233. nterruption of facsimile or modem transmissions caused by somcone picking up an extension instrument to make a call Price 19 99 CIRCLE 75 ON FREE INFORMATION CARD Braun Multipractic Deluxe Food Processor Are you or is someone you know a dedicated serious cook That s the target consumer for the Multipractic Deluxe Variable Speed Control Food Processor UK 40 trom Braun Inc 66 Broadway Rt 1 Lynnfield MA 01940 The company calls this the ultimate kitchen tool for the cook who demands superior performance The UK 40 slices shreds cuts grates and can also knead up to two loaves of bread An adjustable disc system allows one disc with five cutting inserts to perform the same functions as 32 separate discs In preparing French Fries alone the Multipractic Deluxe offers no fewer than 18 slicing thicknesses and 11 different French fry julienne settings Price 140 CIRCLE 76 ON FREE INFORMATION CARD AM FM Electronic Clock Radio Multipractic Food Processor 8861 H38OL2O GIZMO Page 11 57 Four Head VCR LICI Compact Facsimile Unit HANDS ON ELECTRONICS 58 Page 12 GIZMO ytes Hitachi Four Head VCR On screen programming information was the big news in VCR s a couple of years back but now other bells and whistles have overtaken it as hot options for home video But that hasn t stopped Hitachi Sales Corp of America 401 W Artesia Blvd Compton CA 90220 from developing a ne
234. ntro labeled flash To re move a call from hold the FLASH button 15 pressed Depressing the HOLD button and then turning off the 5 power via a side mounted switch the user can go to another extension on the same line and the Swisstel automatically disconnects If a Swisstel is used in conjunction with call waiting the user presses the FLASH button to receive the second call pressing it a second time to return to the first con versation The same control disconnects a call and brings up a dial tone without turn ing the Swisstel off and on again in lieu of hanging up the phone An on off signal light indicates when the telephone is on and the same light blinks when dialing in the pulse mode A good feature because there s no audio in dication of dialing which for a first or second time user can be disorienting to say the least The bottom third of the Swisstel torso is jointed allowing the user theoretically to adjust the mouthpiece for maximum comfort and audio clarity That is where our problems with this extension of you began Frankly neither ear nor mouth is well served by the phone sound quality is muffled at best What s the use of a phone no matter what its color or the elegance of its design if you can t speak and hear clearly through it Maybe as a decorator accessory The instruments thin profile and six inch length allows the Swisstel to hang unob trusively on a well decorated wall As
235. odule that can record or deliver a short message it s time to come up with some applica for the device One gadget I plan to make is a telephone answer only ma chine That unit will answer the tele phone at night after one ring tell the caller to try again in the morning and then hang up My sleep is important to me Such a device can also be put to good use answering unattended office telephones perhaps providing business hours or other information to callers The module also will make an excel lent voice alarm for an automobile theft alarm system Once the system is actuated your voice will blare out from a PA loudspeaker hidden under the hood calling for assistance from the police The alarm can be configured to trigger the module at regular intervals perhaps once a minute with a con ventional siren blasting in between those messages Another idea would be to insert the module into a microphone line so that it will record selected segments of your comments Later those comments can be played back at the press of a button Used that way the device can be useful for paging an often needed associate or even in meeting situations Just think as a chairman of a meeting you can call for order just by pressing a button That ll save a lot of energy on your part GRAYSCALER Continued from page 26 computer s 9 pin RGB output connector On the back is a phono jack to match the conventional coaxial or pla
236. og free MAC ROCOMA 15HB Main Street Washington PURA PA 18977 Creditcard orders 24 hrs 215 736 3979 KITS parts plans We have hard to find parts Variable tuning capacitors tuning coils crystal headphones germanium diodes shortwave crystal CB radio kits no soldering Very inexpen sive Send large SASE for catalog YEARY COM MUNICATIONS 12922 Harbor 800H Garden Grove CA 92640 Cable TV Converters Why Pay A High Monthly Fee Jerrold Products include New Jerrold Tri Mode SB 3 Hamlin Oak VN 12 M 35 B Zenith Magnavox Scientific At lanta and more Quantity discounts 60 day warranty For fast service C 0 0 or ders accepted Send SASE 60 cents postage or call for info 312 658 5320 MIDWEST ELECTRONICS 5143 W Diversey Chicago 60639 MC Visa orders accepted No Illinois orders ac cepted Mon Fri 8 A M 5 CST COMPUTERS impossible to obtain Spare parts and diagnostics The Commodore Diagnostician 7 000 sold 6 95 plus 1 00 postage KASARA MICRO SYSTEMS INC 31 Murray Hill Drive Spring Valley NY 10977 1 800 248 2983 or 914 356 3131 EDUCATION amp INSTRUCTION orming Magicians with a plastic membership card that has your name gold embossed You get a one ar subscription to our quarterly newsletter IT S Order now 29 95 for each course 3 50 postage and handling New York residents add applicable state and local sales tax
237. oks Modern Opte De vico Proyectt true base GREAT ELECTRONICS PAPERBACKS FROM ETT Computer Ter minelegy BP195 INTRODUCTION TO SATELLITE 9 95 A definitive introduction to 9 G 99 95 Covers the subject written for the professional engineer electronics enthusiast or others O 8P23 ETTING THE MOST FROM YOUR MULTIMETER basics of analog and digital meters Methods of component testing includes who want to know more before they buy 8 x 10 in 3 s tors an act assive devices 128 20 PROGRAMS FOR THE ZX SPECTRUM AND 16K ZX82 5 75 CM M IDE Included with each program is a flow chart and a description of what happens BP36 50 CIRCUITS USING GERMANIUM SILICON amp ZENER DI Notes for converting programs for use on other computers are also included ODES 5 50 A collection of useful circuits you ll want in your library BP235 POWER SELECTOR GUIDE 10 00 Complete guide to semiconduc 1 BP37 50 PROJECTS USING RELAYS SCR S amp TRIACS 5 00 Build pri tor power devices More than 1000 power handling devices are included They are onty indicators light modulators warning devices light dimmers and more tabulated in alpha numeric sequency by technical specs Includes power diodes Thyristors Tnacs Power Transistors and FET s C BP39 50 FET TRANSISTOR PROJECTS 5 50 RF amplifiers test equip C B
238. ommercials and identifica tions along with lively Latin music at around 1000 UTC East Germany 17 880 kHz Radio Berlin International RBI is heard here at 1120 UTC with world news in En glish Some interference can be ex pected though Ethiopia 9 560 kHz The station used to announce as the Voice of Revo lutionary Ethiopia but more recently the revolutionary has been dropped from the announcements Look for this in English with a program called In troducing Ethiopia shortly after 1500 UTC International Waters 6 210 kHz Unlicensed Radio Caroline operating from a ship off Great Britain has been using a medium wave frequency of 588 kHz for quite some time It has since added 6 210 kHz shortwave and has been rather widely heard in North America at various times from around 2300 to 0600 UTC Japan 15 300 kHz Radio Japan has been heard with its Hello Amer ica English language programming at 2340 UTC Kenya 4 934 kHz Missing from the air for some time the Voice of Kenya VOK is again being noted here at around 0300 UTC with East African news in English at 0300 following a 6 time signal on the hour Mexico 11 769 kHz Radio Mexico International RMI in Mexico City is being heard in Spanish on this frequen cy at around 1430 UTC Somalia 7 199 kHz Radio Mogadishu despite some interference from the Voice of America VOA on an adjoining frequency has been logged here from
239. or and external speaker jack Those extras are easy to add so we ll leave the details to the reader It s also a good idea to insert a fuse in the line between the project and the power supply Speaking about the power supply it is important to use one that is well regulated Computer grade 5 volt supplies are ideal for that they are readily available and are relatively low in cost The prototype makes use of a surplus Colecovision video game wall plug supply Set Up and Use The first step is to set the four position DIP switch S2 to match your configuration Table 2 shows the proper settings for the switches for different set ups For instance if vou are using the serial port and are sending at 1200 baud switches 52 52 and 52 should be set on off and on respec lively Switch S2 d is used to determine the type of delimiter separator that will be used With switch S2 d set to off the circuit will speak output when vou hit a carriage return It that switch is set to on the circuit will speak each time vou hit the space bar or type a period or any other non letter or non number character The easiest way to use the project is to load vour communi cations modem program and enter its terminal emulator mode Then just type away on your keyboard and listen to your words over the speaker If you want to address the circuit from BASIC there s a sample program in Listing That program is written in GFA BA
240. or 5 000 ohm potentiometer for the application That is the load resistance R J Measure the open circuit or no load output voltage of the generator at terminals and B as you did before and record the value as Vs Assume that it is 8 volts 4 Connect the potentiometer across the voltage source as a variable load resistor R as Fig 5 shows Connect a voltmeter or oscilloscope across the load resistance Vary the load resistance until the output voltage V drops to one half of the open circuit value In that case you would adjust the potenti ometer until the load voltage was 4 volts 5 Without disturbing the potentiometer disconnect it from the voltage source Then using an ohmmeter measure the resistance between the arm of the pot and the end you con nected to the circuit in this case terminals 1 and 2 The resistance value will be equal to the output resistance of the circuit or Assume that you measured a value of 650 ohms across the potentiometer You would know then that the output imped ance was 650 ohms Why does the technique work It works because you adjusting the load resistance to half the output voltage and so you are dividing the output voltage into two equal parts one part of which is dropped across the load itself which you are measuring while the other half is dropped across the internal resistance If the load voltage and internal resistance voltages are equal then their resistanc
241. orescent bike light aringing telephone alerter and more Each chapter contains a description of the circuit construction details photographs and dia grams and a discussion on how to use the circuit Complete parts lists accompany each pro ject and a separate chapter lists sources for new and surplus parts and explains when it is better to buy used parts A chap ter on construction contains advice on tools and materials soldering irons test equip ment and various construction methods In addition to the 20 main projects a chap ter on electronics contains some simple cir cuits and helpful hints on circuit design and modification 20 innovative Electronics Projects For Your Home is available for 13 95 from Tab Books Inc Blue Ridge Summit PA 17294 0850 Tel 1 800 233 1128 CIRCLE 98 ON FREE INFORMATION CARD PRINTER TROUBLESHOOTING amp REPAIR by John Heilborn Syndicated computer columnist John Heilborn has written this book for intermedi ate to advanced computer users with a ba sic understanding of electronics It provides answers to the most common printer repair problems and covers dot matrix ink jet and laser printers Printer Troubleshooting amp Repair begins with a description of each type of printer and how they work Theory of operation design concepts and component identifi cation are discussed followed by basic troubleshooting techniques By u
242. os of the resistances are equal the bridge is said to be balanced If that is true the voltage at A is equal to the voltage at B with respect to ground and no current flows through the load resistance Changing one of the arm values will cause the bridge to become unbalanced Depending upon the nature of the change that will cause current to flow through the load resistance from A to B or from B to A depending on the conditions Our job is to calculate the current in R given the values in Fig 12 Bridge circuits in general are a pain in the neck to analyze Particularly if you wish to determine the amount of current through the load for different values of load resistance The computations are complex messy and time consuming The chances for making an error are also high But then along comes Thevenin s theorem to the rescue There is no reason why you can t convert the more complex circuit into a simple Thevenin s equivalent Let s see how to do that Begin as before by removing the load resistance from the circuit To find the Thevenin s equivalent voltage all we have to do is to compute the amount of voltage between terminals A and B That shouldn t be too difficult n examining the bridge circuit without the load you may recognize the fact that it actually consists of two voltage dividers connected across the source voltage If we redraw the circuit as shown in Fig 13 you will see that more clearly One voltage divider is
243. ose NPN transistor C5 47 yF 16 WVDC electrolytic capacitor Rid 12 10 000 7 5 resistor Rii 15 000 ohm Va watt 57o resistor Perfboard material enclosure IC socket wire solder hardware etc ured as a low frequency oscillator with the off on time or duty cycle equal to about one second each The output of 02 at pin 3 is used to turn Q2 on and off at the rate of oscillation The collector of Q2 can be connected to point A in Fig 1 to turn the audio output of the circuit on and off WIRE FENCE MOUNTEO ON STAND OFF INSULATORS ue TO The Control Oscillator s operation is simple When Q2 of Fig 2 is tied to point of the Chaser circuit in Fig 1 the Chaser circuit oscillates de signed feeding its output signal to SPKRI as long as Q2 Fig 2 is turned off But when the output of the 555 swings positive Q2 Fig 2 turns on and pulls the base QI Fig 1 low That low turns off the output of the speaker When the output of the 555 swings negative Q2 Fig 2 turns off allowing the output of the oscillator in Fig 1 to be passed to the speaker To change the 555 s frequency ex periment with the values of RIO RII and C5 To lower the rate of oscillation increase the values of those compo nents and to increase the rate decrease their values The duty cycle of the cir cuit can be varied by changing the val ues of RIO and RII 9 TO 12 VOLTS SOUNDER CIRCUIT
244. ost to repair those units is prohibitive and ad vise them to buy new equipment It seems a shame to junk those units that look almost new Can you recom mend any books about servicing that equipment Where can can obtain them E W O Odgen IL Our sister magazine Radio Elec tronics ran a story on servicing cord less telephones in their June and Julv 1985 issues Those magazines can also be ordered through the Reprint Book store Starlight Serenade was very happy to see my article Starlight Synth in the June 1988 is sue of Hands on Electronics However the schematic you printed contained few errors In Fig 1 BI should not go between the collector and emitter of 15 In stead it should go between pin 14 and 7 of the 556 timing chip Also in Fig 1 SI should be between the posi tive lead from Bl and pin 14 of that integrated circuit hope that straightens out any prob lems your readers might encounter Timothy A Riggs Making Air Waves like your magazine and hope you keep up the entry level electronics articles have a question regarding the Sonic Jacket featured in the Gizmo Bytes section in the July 1988 issue It con tains speakers an amplifier and a bat tery pack built into the jacket itself Can you picture a person trying to explain that to Airport Security W M S Marina CA It might be fun to watch But as vou m
245. osts 149 95 A 50 foot extension cable is available for 20 00 and adapters which allow the unit to stand up to 2 inches off the window cost 3 00 For further infor mation contact Electron Processing nc Sales Department P O Box 708 Medford NY 11763 Tel 516 764 9798 Compact Loudspeaker System The Bose RoomMate compact high fidelity loudspeaker system is AC DC compatible It features an AC DC power jack with a removable AC power cord for complete portability The sys tem consists of two full range Bose speakers a two stage active equaliza tion network distortion limiting cir cuitry and a dual channel power ampli fier in two 7 x 10 X 7 inch en closures The cabinets are light weight durable and temperature resistant for outdoor use CIRCLE 85 ON FREE INFORMATION CARD The RoomMate II system can be plugged into any sound source with a headphone jack including CD play ers computers personal stereos elec tronic keyboards and clock radios With its small size and high quality sound the system is a good indoor choice wherever there are space and budget constraints The optional Power Pack is a re chargeable battery pack weighing less than five pounds that allows the Room Mate II to play at full volume for up to 12 hours on a single charge It is avail able with 110 volt 100 volt 220 volt and 240 volt rechargers and recharges overnight The 7B 2 Travel Bag 18 another op tion
246. otor assembly to the metal chassis Check the continuity of the motor using the low ohm range of an ohmmeter A very high or out of range reading may indicate bad brushes an open field coil or poor terminal connection s Measure the voltage across the two motor terminals Go directly to the motor wire terminal connections for those tests since the common wire may not be grounded to the chassis The motors may operate with from 3 to 18 volts DC A portable cassette player s motor may operate on 3 to 6 zl Ld VEPLI n o es All small parts are mounted on the PC board after drilling out the holes in the etched wiring Do not fasten the board to the bottom of the case until it s tested volts while a boom box player s motor may operate with 6 to 12 volts For a portable player you can determine a motor s operating voltage by finding out the total battery voltage Suspect a defective motor when there is normal voltage at the motor terminals but there s no rotation Remove the small motor belt and rotate the motor pulley The motor should be replaced if you can feel a pull while manually rotating the pulley or if the motor starts to spin The intermit tent or erratic motor may suddenly stop during operation or just fail to start up Intermittent rotation may be caused by a dry or frozen motor bearing dry bearing may make a squeaky noise as it rotates Sometimes a drop of light oil on
247. our radio By Larry Lisle K9KZT The coil is wound on a l inch dowel 11 inches long Anchor holes are drilled through the rod 2 inches from each end and the coil is wound between them with 22 enameled wire Make sure the coil s lead lengths are amply long and secure the coil to the board with a pair of corner brackets Trim the coil leads as appropriate then scrape or sand the enamel off the ends of the wire from the coil and connect the end of the coil nearest the capacitor to the Fahnstock clip and the wire from the far end to the stator stationary plate contact You can solder the wire as shown or use an alligator clip If the variable capacitor has more than one set of plates use the largest section only Don t use the screws sometimes found on the sides of variable capacitors for attaching wires The Antenna Although I ve had very good results using just 30 feet of wire indoors for best results an outdoor antenna that is long high and in the clear is hard to beat You can use regular insulators to keep it away from metal objects but rubber bands will also work The wire for the antenna can be any diameter You can make an almost invisible antenna by using very fine gauge wire The antenna should be attached to the coupler at the Fahnstock clip Later you might want to experi ment with directional antennas such as the loop or beverage You can have a lot of fun just tuning around the dial You ll be surprised how far yo
248. over the woofer hole protects the speaker panel from breaking during work on the enclosures Woofer Mounting If you re unsure of the woofer s polarity test the it by connecting a 5 volt battery to the woofer terminals Mark the terminal connected to the positive pole of the battery if the cone moves outward upon contact Mark the other terminal if the cone sinks backward into the cabinet The mark identifies the positive speaker terminal At this time it is a good idea to temporarily mount the wooter using foam weather stripping instead of sealer Apply the weather stripping around the cut out and connect the speaker cable being mindful of the polarity but don t solder Install the woofer by threading the Vie inch bolts into the T nuts you ve inserted into the back of the speaker board The temporary mounting permits you to make further changes in box damping or wiring if necessary Leave the cabinet in the reclining position until the silicone rubber behind the driver has set Adjustment Connect your new speakers to an amplifier or receiver and test them at low volume Rotate the L pad shaft to see that it controls the tweeter output correctly Then adjust it to the point that makes the sound from the woofer and tweeter blend into one voice You should find that your towers perform well with any kind of music If you want to hear how they reproduce unusual sound effects try them with the Pink Floyd disc of Dark Side of the
249. owledgeable personne quality merchandise providing the best values in leading edge technology 741800 7415112 29 7415122 48 7415123 49 7415124 75 7415125 39 7415126 39 7415132 39 7415133 49 7415136 39 7415138 39 7415139 39 7415145 99 7415147 99 7415148 99 7415151 39 7415153 39 7405154 49 7405155 59 7415156 49 7415157 35 7415158 29 7415160 29 7415161 39 7415162 49 7415163 39 7415164 49 7415165 65 7415166 95 7415169 95 STATIC RAMS 450ns 450ns 200 5 POWEE 100ns 200 5 150ns M CMOS 200ns CMOS LP 150ns iCMOS I P 120ns CMOS LP 150ns CMOSH LP 120ns CMOS LP 150ns CMOSMHLP HIGHTECH SPOTLIGHT EPROUMS 128K x8 ORGANIZATION 200 NS CMOS DESIGN FOR LOW POWER 34 95 7415241 7415242 7415243 7415244 7415245 7415251 7415253 7415257 7415258 7415259 7415260 7415266 7415273 7415279 7415280 7415283 7415290 7415293 7415299 7415322 7415323 7415365 7415367 7415368 7415373 7415374 7415375 7415377 7415390 741500 741501 741502 741503 741504 741505 741508 741509 741510 741511 741512 741513 741514 741515 741520 741521 741522 741527 741528 741530 741532 741533 741537 741538 741542 741547 741548 741551 741573 256 4 1024 4 1024 4 2048 8 204828 2048 8 2048 8 204828 204828 2112 2114 21141 2 TMM2016 100 HM6116 4 HM6116 3 HM6116LP 4 HM6116LP 3 HM6116LP 2 HM6264LP 15 819248 HM626
250. pability and presently no manufacturer of pointing devices for PC s other than MicroSpeed has ballistic drivers Lightgate Remember Felix The Cat Like the original Lightgate s Felix 1s a would be mouse killer that works like a cross between a joystick and a digitizing tablet A single switch 15 mounted at the top of a post that you hold between your thumb and second finger like a pencil your first finger operates the switch The post moves in an area that is about one inch on a side along the perimeter of that area are twelve Spots areas that you can program to deliver simulated keystrokes like a keyboard macro processor You can activate the Hot Spots either alone or in combination with your keyboard s CTRL ALT and SHIFT keys providing total of 60 Hot Spots Lightgate supplies files that program the Hot Spots for effec tive use of Lotus 1 2 3 AutoCAD and other programs You can also create your own easily In operation Felix provides a one to one correspondence with the screen of whatever program you happen to be run ning In other words regardless of the program when you move the Felix pointer to the upper left corner your on screen pointer wil move to the upper left corner When you move the Felix pointer to the lower right corner your on screen pointer will follow accordingly That correspondence provides a comfortable frame of reference unlike the typical mouse or trackball use of which in com
251. pad can be a chore On the other hand after you find it you can just plop it down on top of whatever is already there 8861 H38O0100 ai HANDS ON ELECTRONICS eo e Documentation For a product so easy to use as a pointing device documen tation may not seem important That s true if all you re going to do is plug the device in and use it However if you want to do anything more perhaps write your own graphics soft ware or create a menu system for your favorite word pro cessor you ll need more information Some manufacturers provide what you need with the device others charge extra Further Considerations The optimal number of buttons on a pointing device is a hotly debated theoretical issue but most devices today seem to come with three buttons presumably because you can simply ignore the extra buttons if your software does not use them Many pointing devices come with bundled software in cluding CAD Computer Aided Drafting drawing and paint ing and desktop publishing programs as well as special software that allows you to build menus for running programs that don t have built in support for pointing devices As for power source some pointers require only a few milliamps of current which they can pick up from the serial port they re attached to Others require a separate power transformer which increases cable clutter At least one mouse the Manager Mouse Cordless has a built in re chargeable batter
252. parison is like being in con stant free fall The device has a couple of faults however The documen tation seems more interested in being cute than in supply ing information Second the Felix driver software uses about Products Discussed Felix 199 149 for Maclntosh version Lightgate 6202 Christie Avenue Emeryville CA 94608 Tel 415 596 2350 CIRCLE 31 ON FREE INFORMATION CARD KB5153 249 KeyTronic P O Box 14687 Spokane WA 99214 0687 Tel 509 928 8000 CIRCLE 32 ON FREE INFORMATION CARD Serial Mouse 119 LogiTech 6505 Kaiser Drive Fremont CA 94555 Tel 415 795 8500 CIRCLE 33 ON FREE INFORMATION CARD Serial Mouse 150 Microsoft Corp 16011 N E 36th Way Box 97017 Redmond WA 98073 9717 Tel 206 882 8080 CIRCLE 34 ON FREE INFORMATION CARD PC Mouse 149 MSC Technologies 2600 San Tomas Expressway Santa Clara 95051 Tel 408 988 0211 CIRCLE 35 FREE INFORMATION CARD PC Trac 119 serial 139 bus FastTRAP 149 se rial 169 bus PDA 69 MicroSpeed Inc 5307 Ran dall Place Fremont CA 94538 Tel 415 490 1403 CIRCLE 36 ON FREE INFORMATION CARO Manager Mouse Cordless 199 Numonics 101 Commerce Drive Montgomeryville PA 18936 Tel 800 247 4517 CIRCLE 37 ON FREE INFORMATION CARD Serial Mouse 49 95 Radio Shack One Tandy Cen ter Fort Worth TX 76102 CIRCLE 38 ON FREE INFORMATION CARD 40K of memory which 15 three to five times as m
253. politics and religion The format of the show is roughly half music half talk The music covers the entire range from up tempo jazz to Irish that s right Irish country and western singer Meyer s friendly easygoing chit chat may or may not be your cuppa tea but Happy Sta program s longevity says some thing about its audience Radio Nederland cites a Canadian shortwave survey that it says showed that the average number of listeners per Sunday is 200 million worldwide If so that may explain how after 60 years Happy Station is going strong Tom Meyer longtime host of Radio Neder land s The Happy Station program the oldest show on shortwave together with his friend Klaasje Another Birthday Not as easy to log as Radio Nederland is one of the pioneer short wave broadcasters of Latin America Radio Illimani which this year cele brates 55 years on the air It was on July 15 1933 that Radio Illimani went on the air from La Paz the capital of Bolivia with a medium wave outlet and a one kilowatt shortwave transmitter made by the Philips Co in Holland Their shortwave service ended in 1975 for technical and economic rea sons but five years later under a new director Radio Illimani returned to the SW band Today the Bolivian short wave station operates four recording and broadcasting studios in downtown La Paz The station operates on medium wave and FM i
254. pose control accesses a three image memory brings up a graphic on the screen or shows the live image of the user Transmission is activated with a touch of the send key Once warned up about 20 seconds the Visitel is ready to display and send images on a video screen offering resolu tion described as 96 by 96 pixels and 32 levels of gray scale Of course if you plan to trade video snapshots it would help if the party at the other end is also equipped with a Visitel The image sent and received has more in common with a facsimile transmission than say a television broadcast Quality is comparable to the output of a surveillance camera might be imagined with a screen boasting 32 levels of gray scale the GIZMO Page 1 886 HAEOLOO 47 HANDS ON ELECTRONICS picture is monochromatic in the extreme Even a fairly wide brightness range doesn t completely remove a sort of black and white solarization effect that is characteristic of Visitel images Lighting has its effect and we found that moving the device around to take ad vantage of the best lighting conditions could improve the final image n the in structions 175 suggested that the Visitel should be lit from above and behind for best results There s also a warning against pointing the camera at any bright light Such exposure could burn an image into the camera The lens to caller distance that offers the clearest image is about
255. pt the speaker board the smaller chamber it should be added to the sides back and bottom partition Acoustical Touches When the adhesive has set apply another thin coat of Liquid Nails and staple sections of thin indoor outdoor carpet over the roofing material with the foam side facing the wood The ideal carpet for this job is about inch thick Half of the thickness consists of a polyurethane foam backing The com bination of carpet and roofing does a good job of deadening the enclosure walls Staple pieces of acoustical Fibreglas l inch thick to each inner surface of the large chamber except the speaker panel Place a small piece on the upper surface of the bottom partition in the second chamber If you have any left add it to the layer of Fibreglas on the inside of the back panel in the large chamber directly behind the woofer The Back and Grille Install the back panel If you want to conduct any experi ments with damping material run a strip of foam weather stripping around the edges and across each partition then install the panel with screws For the final installation use a liberal bead of silicone rubber sealer on the rear cleats and nail down the back The silicone rubber makes a perfect seal for any joint that you can t reach to caulk later After gluing down the back you can still gain access to the interior of the larger chamber by removing the woofer Cut the 1 inch lattice material to the lengths descr
256. r under C operations M you need this book nitidis ee BP104 ELEC TRONIC SCIENCE PROJECTS 5 75 Simple to complex group of proyects with a strongly scientific flavor 1 126 20 PRO GRAMS FOR THE ZX SPECTRUM amp 16K 2 81 5 75 All programs fun on both machines Include Charts and how 10 to on other computers PCP104 ELECTRONICS BUILD AND LEARN 9 95 starts off with construction details of a demonstrator and shows a variety of Circuits for experimenters ELECTRONIC TECHNOLOGY TODAY INC Box 240 Massapequa Park NY 11762 0240 Name Address City Prajects tx BP143 INTRO PROGRAMMING THE 600800 XL 5 95 comple ment to Ihe Alan user s manual Even shows how to use animated graphics BP131 MICRO IN TERFACING CIRCUITS BOOK 2 5 75 Inieriacing sound and speech generators temperature and optical sensors motor Conirol and more eciam Get Taur Led asd Ones 1 BP127 HOW SIGN ELECTRONIC PROJECTS 5 75 How to use standard ct elements tO make cuslom electronic prop ecis BP92 CRYSTAL SET CONSTRUCTION uw 5 50 variety of crystal radio recervers for the experimenter and BP106 MODERN OP AMP PROJECTS
257. r s prototype where the two air core coils LI and L2 are mounted The top deck consists of a 9 inch diameter circle cut from 42 inch thick fiber board Four 3 inch lengths of inch dowel hold the 9 inch coil base above the perfboard Select a drill bit slightly smaller than the dowel rod s diameter and drill the four mounting holes in the 9 inch circle to match the illustration Position the 9 inch circle on the baseboard at about the center and mark the location of each hole Drill each location on the baseboard with the same bit to a depth of about 2 inch If the two layer Tesla coil seems like too much bother to HOLE FOR GROUND Po 1 2 SPARK GAP MOUNTING DOWEL HOLE HOLE 5 1 2 12 9 INCH DIAMETER 1 2 INCH THICK FIBER OR WOOD CIRCLE ALL OIMENSIONS IN INCHES Fig 4 Shown here is the general layout of the top deck of the author s prototype which supports coils L1 and L2 Four 3 x wooden dowel rods hold the 9 inch circular base above the perfboard and other components Here is what L1 left and L2 right should look like once completed Although winding L2 may appear difficult it can be done In an hour by hand or in 15 minutes by lathe 8861 H38O100 v HANDS ON ELECTRONICS duplicate then build a single level unit on a larger wooden base to suit your own needs Actually any good layout scheme that respects the dangers of high voltage should do quite well
258. ral minutes to determine if it s intermittent Grasp the motor pulley and stop it momentarily Notice if the motor speeds up at once Re place the motor if it will not start up or if it is intermittent PHONO SWITCH AC PHONO MOTOR The phono motor be checked for continuity with the low ohm scale of the ohmmeter The resistance measurement may be quite low so be sure to set the scale to low Disc or Camcorder Motors The really small motors found in CD players or camcorders may have several leads connected to them Some of the motors are brushless types In most CD players the loading disc and carriage motors have only two leads while in other players the disc and carriage motors may have more Like wise the focus zoom and iris motors in camcorders may have two motor leads Sometimes three separate leads are fed to the camcorder motor with the third usually black wire grounding the motor assembly Be careful when testing or applying external voltage to small motors Low range resistance measurements may be made and external voltage may be applied to camcorder motors with two leads Remember some of the motors are designed to operate with a 0 5 volt to 1 volt DC Start R4 at zero and monitor the applied voltage If the motor does not turn flip the DPDT switch Most of the motors operate in either direction while in operation except the spindle or disc motor found in CD players Suspect a defective motor
259. ranches of physics such as general relativity astrophysics and cosmology During the experiment the research team will measure the changes in the force of gravity at different depths within the remote location known as DYE 3 where the United States in cooperation with the Danish government operates an Air Force radar station The gravity meter will be lowered down the borehole to a depth of about 5 000 feet and then raised in 300 foot intervals where measurements will be taken About a dozen readings will be taken as the instrument moves up the hole Calculations from these measurements will determine the value of the force of gravity inside the hole as a function of the position of the instrument in the huge ice sheet The gravitational effects of the earth beneath the ice will be factored out of the final calculations The investigation is supported by the NSF Divisions of the Polar Programs and Physics Los Alamos National Laborato ry and additional funding from Amaco Production Company Mobil Research and Development company and the Air Force Geophysics Laboratory in Bedford Massachusetts Continued on page 106 IF ANDERSON HAD USED 5 MEM QUALITY c PAIS might still be in business today But he didn t and he isn t Maybe he forgot that in a service business like his quality is just as important as finding the best price If he had been buying his parts from MCM he would have discovered that we o
260. ravitational constant to better than part in 1 000 over depths of about 300 to 5 000 feet down the borehole To assure optimum accuracy the one half inch steel cable that will be used to lower the gravity meter into the borehole will be lowered into the Consolidated Silver Mine in Idaho in late June to record its absolute length The gravity meters will be calibrated in Alaska at the same latitude as the test site in Greenland At the test site gravity survey will be conducted of the region surrounding the borehole and radar soundings will be used to map the structure of the ice and the underlying bedrock This experiment could have a profound effect on our understanding of the physical universe said Ander There are not many opportunities for geophysics to make a funda mental contribution to pure physics but this is certainly one of them ia Quit smoking WERE FIGHTING FOR America e YOUR LIFE Association EIA CEG AUGMENTS DIGITAL AND MICROPROCESSOR COURSE HIGH TECH PARTS KITS NOW AVAILABLE Capacitors and integrated circuits he members of the Electronic Industries Association Con Digital to perform all digital exercises 1 sumer Electronics Group EIA Microprocessor through 25 of the Digital Micro through the Product Services Course processor course book listed in the table of contents Some parts have Committee has marketed the been included for the microproces illustrated
261. rd see photos Figure 3 shows the positioning of the perfboard and ott board components on the baseboard Mount the fully popu lated perfboard assembly to the baseboard using four 14 inch plastic spacers and wood screws The location of the sub assemblies on the baseboard isn t too critical so long as the general layout is followed Keep all wire leads as short as possible especially around the high voltage circuitry A 2 2 inch piece of aluminum is formed into an L bracket which is used to hold SI and FI see photo and is mounted on one corner of the baseboard A 5 X 3 inch piece of aluminum mounts to the opposite corner and functions as the heat sink for the two power transistors Q3 and Q4 A simple band is formed from aluminum to hold T2 in place Recall that CS is really three 500 wF doorknob capacitors PARTS LIST FOR THE SOLID STATE TESLA COIL SEMICONDUCTORS U1 555 oscillator timer integrated circuit Q1 2N3906 general purpose PNP silicon transistor Q2 MJE34 ECG197 or similar audio frequency PNP silicon power transistor Q3 Q4 2N3055 NPN silicon power transistor D1 D4 1N5408 100 PIV silicon rectifier diode RESISTORS All resistors are 5 units unless otherwise noted R1 470 ohm R2 R7 R8 1000 ohm R3 R4 6 10 000 R5 2200 ohm R9 R12 100 ohm 1 watt resistor CAPACITORS C1 2200 4F 50 WVDC electrolytic 2 47 25 WVDC electrolytic 3
262. rently in use in this country Fellowes Manufacturing 1789 Norwood Ave IL 60142 is right on time with its introduction of a popularly priced Workstation Anti Glare Filter Lightweight the unit hangs from the top of a computer monitor with two weighted clips Besides cutting down on screen glare the filter gives screens more contrast in both monochromatic and color monitors Four sizes are available for makes and models ranging from a 9 inch Apple MacIntosh to 15 inch PS 2 Price 24 95 29 95 CIRCLE 79 ON FREE INFORMATION CARD Bose Roommate Il Powered Loudspeaker Need a new roommate The Bose Corp The Mountain Framingham MA 01707 thinks you do namely the company s new Roommate Il Powered Loud speaker That update of the very popular Roommate offers an AC DC power jack with removable AC power cord a new fiberglass reinforced injected styrene cabinet and revised equalization and compression circuitry providing smoother response and better high end performance All that in a package weighing 10 5 pounds Price 279 CIRCLE 80 ON FREE INFORMATION CARD Sharp High Speed Facsimile Aimed at the small business or home office user the new High Speed Fac simile UX 160 trom Sharp Electronics Corp Sharp Plaza Mahwah NJ 07430 sounds as if it s a compact but multi featured communications center With eighteen second transmission speed and vertical resolution of 391 lines per inch the UX 160 can tr
263. roducts along with the recent tremendous increase in fac simile transmission suggest that some thing like the era promised by the 1964 World s Fair picturephone could be on the horizon CIRCLE 51 ON FREE ORMATION CARD hand held recorder that s liable to break often mysteriously at the slightest provocation Sony s WM D3 stereo Cassette Corder dubbed the Walkman Professional and 11 mono Cassette Corder represent the high and low end of a product field practically invented around the brand name Walkman Or did subsequent to our purchase of the budget priced TM 1I it was replaced by the 7CM 2 the Press man Cassette Corder which also 15 mono unit A leading New York electronics store described the WM D3 as the best hand held tape recorder on the market The was purchased in New Orleans The budget priced 11 was a mad deningly unsatisfactory piece of equip ment from the moment it left the store Its mono recording capabilities are far in ferior to similarly priced models from years ago and it also revealed itselt as horrible medium for playback What s more its construction is monumentally flimsy Among sounds the TM 11 proved incapable of clearly recording or playing back were conversations live music and even incidental crowd noises As if in anticipation of our next im pulse the TM 1I came to a quick end withi
264. rough Out the book particularly in the appendices Those appendices summarize editing and formatting commands mouse keyclicks and the Word Command Tree and describe ITT PUSH BUTTON PIEZO WARNING DEVICE Murata Erie PKB8 4A0 High pitched audible alarm Operates on 3 20 20 ma 1 high x 7 8 dia P C board mount CAT4 PBZ B4 175 each XENON TUBE 1 long flashtube prepped with 3 1 2 red and black leads Ideal for electronic flash or strobe projects CAT FLT 3 2 for 1 00 N CHANNEL MOSFET ys IRF 511 TO 220 case We CAT IRF 511 1 00 each 10 for 9 00 cap S P S T N O Push to close r Rated 0 1 amp gt Switching re 0 25 amp carry current P C mount CAT 8 65c each 10 for 6 00 LARGE QUANTITY AVAILABLE 1 3 4 X 7 8 ORDER TOLL FREE 800 826 5432 INFO 81 8 904 0524 FAX 818 781 2653 MINIMUM ORDER 10 00 QUANTITIES LIMITED CALIF ADD SALES TAX USA 3 00 SHIPPING FOREIGN ORDERS INCLUDE SUFFICIENT SHIPPING NO C O D CA 91408 eo 1 CIRCLE 5 ON FREE INFORMATION CARD 8861 4380190 HANDS ON ELECTRONICS RN A BUILD IT BOOKS FOR EXPERIMENTERS Modern OpAmp 4 BP106 MODERN OP Projects PROJECTS 5 75 Wide range of build 223 PROJECTS t projects that use op amps Easy to build board layouts provided for most A variety of projects of all k
265. rth 1 e whenever something is grounding the fence the bias is drained off through the intruder That turns on tran sistor Q3 causing current to be drawn through RI8 With the current flowing through R18 base bias is supplied to transistor Q4 turning it on which in turn causes the relay contacts to close supplying power to the Audible Critter Chaser circuit The on time of the sensor circuit can be extended somewhat by connecting a 47 wF electrolytic capacitor across R18 the cap should be hooked up with the positive lead connected to the drain of Q3 That s a good area to experiment in to tailor the circuit to suit a specific need When installing the fence wire be sure to use a good insulator at each tie point and a ground rod to insure a good Earth ground system If you happen to be close to a powerful radio station a small capacitor might be needed be with very small capacitors say 5 to 39 PARTS LIST FOR THE AUTOMATIC SWITCH Q3 2N4380 P channel JFET Q4 2N3904 2N2222 or similar general purpose MPN transistor K1 500 ta 1000 ohm 12 volt DC re lay C6 100 yF electrolytic capacitor H13 H17 22 megohm a watt 5 resistor H18 10 000 ohm sistor H198 1000 ohm a watt 5 resistor B1 8 volt transistorradio battery Perfboard material enclosure grounding rod wire solder hardware etc 59s re picofarads If the capacitor is made too large the RC time
266. s 4 62 inches 6 6 inches and weighing only 25 ounces the Model ART60 can be conveniently mounted in any car he latest electronic hybridization and inte gration techniques have been used in the miniature radio s circuitry to achieve this compact size The mobile scanner features a fre quency synthesized keyboard control It covers all the conventional police fire and emergency bands CIRCLE 28 ON FREE INFORMATION CARD The Model AR 60 is controlled by an on board microcomputer accessed by twenty keys on top of the unit The LED system provides bright clear chan nel information and verifies frequen cies though a count off system A bat tery retains memory in the event of a power loss A fused DC power cable telescopic whip antenna mobile mounting bracket and hardware and AC to DC con verter are included with the Model ARI60 for its suggested retail price of 189 00 It is manufactured by AOR Ltd of Japan and is available from their wholly owned subsidiary Ace Com munications Monitor Division 1707 East 106th Street Indianapolis IN 46256 Probe Switch The Philips PM 2195 Probe Switch is designed to eliminate the load and interference problems normally associ ated with switching waveforms before the signal is applied to the input probe That allows signals to be switched be tween the probe and the oscilloscope input in typical GPIB systems without significant degradation of bandwi
267. s tem and why MIDI is needed at all Most of the book is devoted to an explanation of what MIDI can do and how to get the most from it The Practical MIDI Handbook cov ers the fundamentals of control codes de scribes the types of equipment and soft ware currently available and explains how systems can be tailored to meet individual requirements While the main emphasis is on actually using MIDI systems theory and technical details are included as well Full details of the MIDI code numbers are provided for those who wish to do their own MIDI pro gramming Also included is advice on deci phering the technical material in the owner s manuals The Practical MIDI Handbook order No PCP103 contains 150 pages including a glossary of terms It is available for 11 95 including shipping from Electronics Tech nology Today P O Box 240 Massapequa NY 11762 CIRCLE 97 ON FREE INFORMATION CARD LEARNING ELECTRONICS THEORY AND EXPERIMENTS by R Jesse Phagan and William Spaulding This comprehensive guide combines elec tronics theory math and hands on experi ence with computer aided instruction using the Commodore 64 128 No previous elec tronics or computer experience is required for understanding the material presented in this book The book s main emphasis is on student managed learning its key istheinvolvement of the student in the learning process Each chapter after the first two introductory chap ters
268. s a socket set a 7 piece jewelers screwdriver set a 10 hex key set 4 screwdriver CIRCLE 44 ON FREE INFORMATION CARD blades a full size handle wire strip per cutter assorted pliers and more Tools are held in a compact 7 x 9 2 inch padded zippered case A Velcro snap closure can hold an optional Beck man DM73 Meter The JTK 97 costs 79 99 For more information and a free catalog contact Jensen Tools Inc 7815 South 46th Street Phoenix AZ 85044 Tel 602 968 6231 Fiber Optics Experimenter Kit Jameco s JE315 Advanced Fiber Op tic Kit is designed as educational device It gives students hobbyists and engineers both a hands on experi ence with tiber optics and a better un derstanding of how fiber optics tech nology really works The JE3I5 includes separate trans mitter and receiver circuit boards and an on board oscillator tor easy circuit testing t accepts analog or TTL input signals and can process multiple ana log and digital signals that have been combined together previously ts fre quency range 15 40 Hz to 6 5 KHz and its circuitry includes 555 timer chip 145 op amp ICs and MFOD73 photo transistor CIRCLE 44 ON FREE INFORMATION CARD The advanced fiber optics experi menter kit complete with step by step instructions theory of operation and tutorial information clearly demon strates
269. s a big part of the 8 mm video story and the Sony lives up to the format s reputation for near point and shoot operation The autofocus is im pressive in its speed while manual control and focus for close ups of small objects increase the handycam s ver satility A six power zoom can be adjusted manually or operated with a control just above the detachable grip on the right of the camera Another well designed con trol feature in the CCD V5 s POWER and CAMERA PLAYER Switch A built in safety catch makes it virtually impossible to set the unit to the wrong function In addition to allowing playback view ing the electronic black and white view finder displays status and function infor mation superimposed over the scene in view Symbols and words offer lighting white balance and mode indicators Date and time can also be displayed and shown on the recorded tape A note to consumers who might be concerned about correct date according to the manual the year indication will return to 1988 when it ex ceeds 2016 So you can figure on 28 years of correct date information Describing the CCD VS naturally isn t nearly as much fun as using it A real pleasure especially for the novice 8 mm video user is the clarity and resolution of the pictures produced With an illumina tion range of 9 to 100 000 lux the manual suggests more than 300 lux as the op umum illumination level both indoors and i
270. s also the Thevenin s equivalent voltage V is Vae Vin VA Vg 10 6 4 volts Since V is greater than Vg A is positive with respect to Now let s find the Thevenin s equivalent resistance As before the load is assumed to be disconnected Next we short out the source voltage as we did before The resulting circuit is shown in Fig 14A That is a good example of how not to draw a schematic diagram To understand the circuit better we can redraw it as shown Fig 14 As you can see we have a simple series parallel combination circuit made up of and R2 in parallel and R3 and R4 in parallel and the two combinations in series We can apply the standard re sistor formulas to the problem 8 First we find the parallel resistance of RI and R2 which we call R 5 That is done as follows R R2 RI R2 6 12 6 12 72 182 4 ohms The parallel combination of R3 and R4 we can designate as and it is computed as follows R 4 R3 R4 R3 R4 12 8 12 8 96 20 4 8 ohms The total resistance then is simply the sum of the two equivalent resistances shown in Fig 14C To find the total all we do is add the two equivalent resistances R4 4 4 8 8 8 ohms Of course the total resistance is the Thevenin s equivalent resistance Rp Rr 8 82 R 42 Fig 15 equivalent of the bridge circuit looks like all the other equivalent circuits indicating the usefulness of Thev
271. s and very loose One of the shields had been crudely pinched at the top to give the grid lead enough clearance to extend much farther down into the can That had been done so that the original HANDS ON ELECTRONICS A more obvious problems In September we concentrated on the dial An internal iam had caused the mechanism to stick and a previous owner had tried to re glass G style 6A8 tube could be ime in less than ideal environ solve the problem by applying brute force to the bandswitch That resulted in some of the metal parts in the dial being badly buckled and twisted The problem looked lot worse than it really was though Once the dial was removed from the set and dismantled the distorted parts were easily straightened in a vise After reassembly the shutter dial assembly worked well and was set aside for later installation In the September column I also fired up the set for the first time Starting at reduced line voltage I slowly increased to the full 117 volt line voltage as it became apparent that the electrolytic capacitors were going to be OK and no short circuits were developing The set then came to though it would pick up only a few strong local broadcast stations There was no trace of hum but signals were distorted and accompanied by strong oscillation Nothing could be heard on either shortwave band Clean Adjust and Straig
272. s it possible for the editors here to do their jobs properly When transistors first hit the hobby marketplace many editors hopped on the bandwagon They were right When integrated circuits appeared some editors were fast to promote their ap plications in hobby areas others were slow The arrival of computers threw the electronics magazine field into turmoil Computers are hardly a new topic even wrote an article on a basic computer project back in 1961 but in recent years that subject area overwhelmed the editorial balance of many hobby oriented electronics magazines Too many of those magazines dedicated 100 of their content to computer related topics and many new all computer magazines were born could understand the introduction of new magazines that were devoted exclusively to computers What could not understand was how or why already established hobby electronics maga zines would tie their future success to one area of electronics To me it was a calamity to see loyal readers who were interested in other areas of electronics so callously ignored and dropped by magazine publishers Of course if a magazine is to grow with its readers change is inevitable Because of that you can expect some change be it ever so Slight in almost every issue of Hands on Electronics But our readers will never be discarded for a keyboard and floppy drive combo or anything else for that matter Now you may ask what s the change for
273. se Cordless is a nice idea with an imperfect implementation As its name suggests this mouse communicates with a separate receiver via infrared LED s and photodiodes The mouse itself has three buttons and a front mounted charging jack In typical use a charge should last for about three days You can operate the mouse while it is charging but the stiff charging cord makes such operation difficult The receiver itself requires power from a power transformer so you can t use the Manager Mouse without a source of 117 VAC so lap top operation is out In operation the mouse has a good feel without the charging cable attached but the software drivers supplied with the device were buggy For example in both AutoSketch and Dr Halo sensitivity provided by the drivers was too low for convenient use Documentation is adequate but no menu software is sup plied or even available Tandy At 50 Radio Shack s serial mouse is the cheapest on the market Its documentation is minimal and no software is included not even the requisite mouse drivers According to the company Radio Shack s versions of MS DOS come with the mouse drivers if your version of DOS has no mouse drivers a local Radio Shack store should provide them to you free of charge Because of its low price I expected that the feel and operation of the mouse might be lacking but fortunately 1 was wrong The feel of this mouse is easily competitive with the others discussed
274. sign on about 0258 UTC with Somali language announcements and Islamic prayers ELECTRONIC PARTS OUTLET TECH TRAINER Il Power Supply and Frequency Generator o cc 00000000 o O9 000000 89 00 Quantity Price 1 2 CHANNEL VHF TRANSMITTER amp RECIEVER With Schematics 8 95 amp 3 DIGIT PANEL METER KIT DCV or DCA 14 95 ujas cc AA Size 1 25 500mAH 1 75 Hobby Motor 6 12VDC Colman 1 75 24 wt 7 50 PWR Resistor 0 25 ELECTRONIC PARTS OUTLET INC 2815 FONDREN HOUSTON TX 77063 713 784 0140 QUANTITIES LIMITED MIN ORDER 10 00 SALES TAX USA 3 SHIPPING NO COD VISA MASTERCARD DISCOVERY CIRCLE 23 ON FREE INFORMATION CARD 8861 H3EOLOO Q3 HANDS ON ELECTRONICS A tur GARR N HAM RADIO _ m HIS EDITORIAL OF May 1988 THE Hands on Electronics editor Julian S Martin correctly recognized that times are indeed changing And agree that it s for the better at least as far as ama teur radio is concerned The reason for his shift and why he s selling his old cabinet is simple computers While Hands on Electronics is not a computer magazine per se hobby elec tronics is becoming more and more linked to or enhanced by personal computers and or microprocessors Thats why I am going to use this month s column to discuss the link be tween computers and
275. sizer Circuit is shown in Fig 3 The serial input from the RS 232 port enters the circuit through U7 the 489 RS 232 receiver chip and is converted from an RS 232 level to a TT L level signal The CTS256 AL2 chip U1 then converts the ASCII charac ters into allophone codes and sends those codes to U3 the TMS4016 external RAM chip Note If you wish you can use a 61IGLP 3 RAM chip that chip is pin compatible with the one specified in the schematic diagram The codes are then transferred to the 5 0256 1 2 U2 through the 74LS373 octal latch U4 Finally the SP0256 AL2 sends out an audio signal to the LM386 audio amplifier 08 Vs osc 1 f 28 2 RESET 05 2 27 3 1 ROM DISABLE ROM CLOCK 26 4 Ci SBY RESET 25 ES c DIGITAL 24 6 4 23 T Voo TEST f 22 8 SBY SERIAL IN 9 LRO ALD 8 SE 11 A1 SERIAL QUT A2 A6 A3 A5 4 5 0256 12 Fig 2 The SPO256 AL2 takes the allophones output from the text to speech converter and converts it into speech A pin out diagram of that device is shown this figure SSE WEEE CTOBER 1988 PARTS LIST FOR THE SPEECH CONVERTER SEMICONDUCTORS U1 CTS256 AL 2 text to speech converter integrated circuit Radio Shack 276 1786 U2 SP0256 AL2 voice synthesizer integrated circuit Radio Shack 276 1784 U3 TMS4016 25 or 6116LP 3 16K static RAM integrated circuit U4 74LS373 octal latch i
276. superfluous by that medium s gradual disappearance Battery powered the unit projects endless loop films as the viewer holds it to the eye Primitive but effective the unit is sold with one film with alternate selections priced at around 2 95 The Movie Viewer s manufacturer Fascinations 309 S Cloverdale D 47 Seattle WA 98108 doesn t sell retail but the product is widely distributed Price 6 95 7 95 CIRCLE 63 ON FREE INFORMATION CARD Swimtech Lap Counter Computer Better swimming through computers might be the slogan of Swimtech 1616 17th St Suite 360 Denver CO 80202 The company has developed an aquatic Lap Counter Computer that keeps track of the basic unit of competitive and training swimming sports the lap A quick tap turns the computer on and it can count laps in increments of one or two At the completion of a lap the swimmer taps the unit again and the LCD freezes for five seconds allowing a quick check of progress Out of the water the swimmer can check total time average lap fastest and slowest lap total lap and calories burned calculations There s even feature to prevent double clocks or bogus readings Price 119 95 CIRCLE 64 ON FREE INFORMATION CARD Desk Top Office Revenger Readers may recall The Revenger G ZMO June 1988 a pocket sized sound effects unit offering a trio of aggressive explosion noises ideal tor zapping enemies Having achieved fame with a unit that looks l
277. t Cortland Street Chicago 60635 or circle the appropriate number on the Free Information Card Permit me to point out that vou can make some modifications or perform Some programming tricks to several other scanners in order to get some ex tra frequency coverage For the most part however it s not usually some thing that be successfully and or easily accomplished In any event you can t snip out a diode and suddenly add the 118 to 136 MHz or 225 to 400 MHz VHF UHF aeronautical bands to a scanner that was intended for basic low and high and UHF band reception That such stunt restored the cellular telephone tre quencies in the Realistic PRO 2004 has apparently given many scanner owners the impression that that was an amazing discovery that offers miraculous fre quency expansion potentials for all scanners the free world Not so Several reprogramming tricks have been offered for frequency expansion in some scanners Of those we have tried most are complex and produce mixed and generally disappointing results Keep in mind that the missing fre quencies in the Realistic PRO 2004 N SCANNERS By Marc Saxon were within the overall frequency range of that scanner In fact the scanner originally received those frequencies and was then factory modified to blank out the PRO 2004 s ability to pick them up So the user modification was mere ly restoring that ability it w
278. t necessarily enhance the fre quency wanted It only enhanced the strongest signal My electronics teacher who s the one who suggested subscribe to Hands on Electronics told me that there isn t a signal to amplify 1 hope he meant it isn t worth the trouble Do you have a schematic and a parts list for a tunable high gain RF ampli fier system for my car radio R W N Canyon Country CA He could be right If the signal Strength is too low in your area no amount of enhancement will help with no signal there s nothing en hance However before we dismiss the ques tion there are a few points that should be considered The characteristic that gives FM reception its interference free performance ts called ef feci In essence if there are two com peting signals in receiver s passband the receiver will lock onto or capture E and more are available from the 4 the strongest one That s why vour en hancer isn t doing the job vou thought it would It is enhancing both the strong and weak signal equally and vour re ceiver is still locking onto the strongest One If ihe distant station vou are inter ested in shares its frequency allocation with the local one vou re out of luck But if vour receiver is poorly designed and has an abnormally wide passband outboard tunable filter help But while such filters are available for other
279. t the it first missing portions of the 800 MHz Please let us hear from you with your band could be restored in the Realistic questions station photos monitoring PRO 2004 scanner we have received s iria ca perdi ss me hints and ideas ete Write to Mare Q atl aski or addi uon Scanners Hands on hi much asking for adding various channel programmable memory 8 digit Saxe n 5 On Sc ners missing frequency bands to many LCD display and 9 band coverage Electronics 500 Bi County Blvd n other scanners including the aeronautical band Farmingdale NY 11735 i an Discover Explore Experience Today s Electronics With Now you can meet the challenges of today s electronics quickly and easily This professional level learning series is as innovative as the circuitry it explains and as fascinating as the experiments you build and explore And it s for anyone who has an interest in electronics from the hobbyist to the professional Thousands Have Already Experienced the Excitement Today s hightech world demands an entirely new and innovative approach to understanding elec tronics That s why McGraw Hill has developed this unique hands on learning method that brings to life the dynamics of the new electronics It s a unique combination of interactive materials that gets you involved as you build and exper im
280. tal cubic volume of the two reflex chambers is about 36 liters or 1 27 cubic feet The tuned frequencies are 40 and 80 Hz Special Precautions It is desirable to use any reflex speaker with an amplifier or receiver with a good infrasonic subsonic filter If such a filter is not available on your audio equipment you can still use tower speakers Just use care in feeding a signal that contains pulses into your speak ers at high power Such pulses can be produced by some turntables FM tuners and other sources You can check your equipment for subsonic garbage by removing the grille from your speakers and watching the woofer cones If the cones show excessive movement also called throw with any audio source use that source with care When you select materials for a part of the enclosures put solidity above appearance If you use plywood a logical choice for the external panels make sure it has no voids or loose layers Good quality hardwood plywood is usually adequate Particle board the suggested material for part of the enclosure is more solid but even it varies in density The sections the quantity required the materials used and their dimensions are listed in Table l Take Note Be aware that the drawings in this article show the dimen sions of the chambers before any special treatment of the panels as described later The final dimensions of the larger chamber are about 7 x 9 x 20 inches The second chamber has th
281. tart your own new age business providing one stop sales and service for musicians technicians and general consumers alike Or simply unleash your own musical creativity with the breakthrough training and equipment only NRI gives you Only NRI Gives You an Atari ST Computer Casio Synthesizer and Innovative MIDI Software You Train With and Keep The Atari ST Series computer included in your course becomes the heart of your own computer controlled music center With its tremendous power superior graphics capabilities and built in MIDI interface the 16 32 bit Atari ST has almost overnight become the computer of choice for todays most knowledgeable electronic musicians The Casio CZ101 digital synthesizer also included in your training is the perfect complement to your Atari ST The polyphonic multitimbral CZ101 which stores up to 32 voices intemally commu nicates with your ST computer through MIDI bringing life to virtually any sound you can imagine Plus you get ingeniously designed MIDI software that opens up amazing new creative and technical possibilities you actually build your own 4 input audio mixer amplifier and you test the electronic circuits at the core of today s new tech equipment with the hand held digital multi meter included in your course No previous experience necessary in electronics or music Su No matter what your background City NRI gives you the skills you
282. the 8 mm camcorder A counter on the editing deck displays the same numbers as the camcorder meter The problem of pre cisely counting frames according to a Hama representative who demonstrated the deck represented a primary tech nological challenge in designing the unit Camcorders in the 8 mm format use frame count system that fulfills the Cut 105 requirements Designing a compan ion model for use with VHS necessitated more elaborate and expensive approach Even in the field of 8 mm video stan dardization is far from universal The unit as it s presently offered works with eight different 8 mm camcorder and player makes in 15 different models With any of those the deck requires a system code The user must set the Cut 10 for the cam corder or player to which it is connected Pressing system code button on the deck brings those words up on the display The user then enters a number correspond ing to the make and model of player cam corder The numeric code comes from a printed list included in the instructions Reflecting Cut 1055 European manufac ture compatible video units include number of brands unknown in the Amer ican market Blauppunkt Bosch Bauer Grundig Bondstec and ITT More famil iar compatible brands include Canon GE Panasonic Sanyo and of course Sony What the system code adjusts the unit for is the passage of seconds between en gagement of controls and activation of the t
283. the cir cuit and play around with R8 and R9 to obtain the most obnoxious sound that you can generate If you only want to irritate four leg ged critters then try reducing the value of Cl to one half the value given in the Parts List or try an even smaller value and see how Rover responds to the near ultrasonic sound The oscillator can be pushed beyond our own hearing range while still producing enough output to drive most high frequency sensitive critters away Warning Do not force an animal to stay in an area where the circuit is in operation And always leave a clear and defined exit for their early departure The animal may become frightened and confused and in that state they can become very dangerous even to their masters Control Oscillator If a continuous irritating tone isn t enough then add the low frequency Control Oscillator circuit in Fig 2 to the circuit in Fig to create a pulsating mind blocking headache producing chaser circuit that should remove even the most stubborn of intruders In the schematic diagram of Fig 2 U2 a 555 oscillator timer is config TO 9 12V IN FIG 1 TO TERMINAL A IN FIG 1 Fig 2 The heart of the Contro Oscil lator is a 555 timer that s configured as a low frequency oscillator whose output at pin 3 is used to turn Q1 on PARTS LIST FOR THE CONTROL OSCILLATOR U2 555 oscillator timer integrated circuit Q2 2N3904 2N2222 or similar general purp
284. time interval for the UJT os cillator The discharge path for the tim ing capacitor C7 is through R22 and the gate cathode junction of SCRI The resistance of R22 sets the maximum gate current and also determines the SCR s on time When experimenting with different values for R22 stay within the limits of 270 to 1000 ohms The Pest Zapper can be used in conjunction with the Automatic Switch in Fig 3 so that it turns on only as needed or with the Control Oscillator for use in intermit tent operation How about combining all four cir cuits and adding a delay to the Pest PARTS LIST FOR THE PEST ZAPPER Q5 2N2647 N channel UJT SGH1 C108B1 200 PIV 3 to 6 A silicon controlied rectifier SCR C7 4 7 uF 16 WVDC electrolytic capacitor C8 20 1 uF 100 WVDC mylar or ce ramic disc capacitor R20 10 000 ohm 4 watt 5 resistor R21 270 ohm 5 resistor H22 470 ohm watt 5 resistor R23 4700 ohm Ya watt 5 resistor RH24 250 000 ohm potentiometer T1 Model Ford spark coil Parfboard material enclosure grounding rod insulators wire solder hardware etc Zapper so that the circuit comes on only after prolonged contact with the sensor fence which would indicate that the Audible Critter Chaser has failed to accomplish its mission There are all sort of possibilities How many can you come up with Until next month go forth and rid a critter electronica
285. ting for stray magnetic fields from other sources and calculates position within an accuracy of 1 45 degrees Price 52 95 CIRCLE 61 ON FREE INFORMATION CARD Case Logic 120 Cassette Case If you re a really big fan of portable audio you should know about the big Audio Cassette Carrying Case CL 120 trom Case Logic Inc 6930 Winchester Cir cle Boulder 80301 As the product press release puts it the CL 120 can store 10 000 miles of music which works out to be 120 boxed audio tapes The bag fcatures plastic trays foam padding and a nylon shell and it can be carried either with an adjustable shoulder strap or built in handle The entire case can be zippered closed As for that 10 000 miles of music as Case Logic figures it A CL 120 fully stocked with home recorded C 90 cassettes will provide access to as much as 180 hours of music At an average speed of 55 mph a listener could drive nearly 10 000 miles more precisely 9 900 miles and never hear the same selection twice We guess that s why the company is called Case Logic Price 29 95 CIRCLE 62 ON FREE INFORMATION CARD Fascinations Movie Viewer It s barely tech let alone high tech but as an item newly introduced to the novelty and premium market it earns points for following the adage if you ve got a lemon make lemonade The Fascination Movie Viewer uses Super 8 footage cartoons travelogs science films which we thought had been rendered com mercially
286. tion and design for readers who are new to Quattro or to spreadsheet software in general Quattro The Professional Spreadsheet Made Easy begins with the fundamentals of creating and using Quattro worksheets entering and editing data saving and re trieving worksheets manipulating blocks of data rearranging and formatting worksheets and printing reports With clear instructions and hands on exercises readers quickly learn to design a spreadsheet modify data and use formulas More advanced concepts and techniques are also presented including graphing da tabase design macros the use of functions and methods of customizing Quattro There is a complete chapter on the principles and strategy of spreadsheet design When those concepts are applied to the specific com mands and techniques presented in pre ceding chapters the result is a sophisticated well designed spreadsheet Four appendices contain an installation guide a summary of Quattro s 100 func tions helpful hints for Lotus 1 2 3 users who are Switching to Quattro and a list of commands Quattro The Professional Spreadsheet Made Easy is available for 19 95 from Osborne McGraw Hill 2600 Tenth Street Berkeley CA 94710 CIRCLE 84 ON FREE INFORMATION CARD ELECTRONIC HOBBYISTS HANDBOOK by R A Penfoid As electronics becomes increasingly com plex the hobbyist is confronted with a tre mendous amount of data The Electronics Hobbyists
287. tudy course in the fun damentals of electronics Written at the tech nician level it can be used alone as a supplement to a regular classroom course or as a refresher course on a particular subject brief introduction to electricity is followed by a discussion of circuit basics and elec tronic devices The book continues with a presentation of electronic communication controls test equipment and troubleshoot ing techniques Some of the other topics that are covered in the text are magnetism resistors inductance and transformers ca pacitors diodes transistors amplifiers and op amps amplitude and frequency and pulse techniques Everything is presented in a self paced instructional format There are many clear and informative illustrations numerous ex amples that help enhance understanding and each chapter concludes with a self test review of the material Crash Course in Electronics Technology or der No 22494 costs 21 95 from Howard W Sams amp Company 4300 West 62nd St Indianapolis IN 462ts 21 95 from How ard W Sams amp Company 4300 West 62nd St Indianapolis IN 46268 Tel 800 428 SAMS CIRCLE 95 ON FREE INFORMATION CARD RADIO S FIRST TWO DECADES Consisting of selections from Radio Start to Finish originally published By Thomas Y Crowell Co in 1942 Radio s First Two Decades is an informative journey back in time Whether you can remember the early days or are a member of t
288. u can hear even low power stations during the day with a good antenna and at night signals from all over the nation can be heard Listening to far away stations on the AM broadcast band was my first introduction to the wonder of radio and elec tronics and I still get a kick out of it ANTENNA Si SA 8861 HASOLOO D HANDS ON ELECTRONICS dm N TOWERS OF POWER Don t be at the mercy of a speaker manufacturer s specs Build your own loudspeakers and you ll know exactly what you re getting By David B Weems seen plenty of tower speakers There are good reasons for their popularity First a tower puts the tweeter closer to normal ear height eliminating the need for a stand Also towers are narrow giving good horizontal sound distribution and better stereo imaging than wider enclosures And they occupy very little floor space Even with their advantages getting good sound from a tower can be tricky There is the danger of nasty resonances when the longest dimension of a speaker enclosure is equal to or greater than three times the shortest dimension Such enclosures can act like pipes which are notoriously resonant Pipe resonance can be reduced by placing stuffing in the enclosure but it can also be stiffled by breaking the pipe into sections For that the double chamber reflex speaker is a natural you have visited any audio showrooms recently you have surely Double Chamber Refl
289. u12 5V MATH COPROCESSORS 8087 8087 2 8087 1 5 8 MHz 10 80287 6 MHz 80287 8 B MHz 80287 10 10 MHz 80387 16 16 MHz 599 95 5159 95 5229 95 5179 95 5249 95 5309 95 499 95 741593 741595 7415107 7415109 7415196 59 7415197 59 7415221 59 7415240 69 7415783 22 95 2 80 25152521 261531 261532 LINEAR TLO7 1 TLO72 TLO74 TLOB2 567 NES70 NE592 1 723 1 1 95 95 HANDS ON ELECTRONICS o 200ns 12 5v 350ns i21V124 PIN 250nsj 12 5V 250 5 125 CMOS 7 95 i250ns 12 5v 6 95 6553648 250ns12 5v 11 95 6553648 250ns 125v CMOS 12 95 rV Program Voltage MEMORY PRICES SUBJECT TO CHANGE DUE TO MARKET CONDITIONS PLEASE CALL TO CONFIRM PRISES TLOB4 1 301 LM3O9K M311 LM311H 1 317 UM317T 1 318 1 319 1 25 LM 320 see7900 LM323K 3 49 LM324 34 LM331 3 95 LM334 119 LM335 1 79 LM 336 1 75 LM338K 4 49 LM339 59 LM340 see7800 353 59 LF 356 99 LF 357 99 UM 358 59 UM38BO 89 1644383 LM386 LM393 LM394H Ti 494 T1497 NES55 556 NE55R 564 1565 1 566 75452 590 75477 1 29 H 5 3 0 220 UM 733 LM 74 1 UM 747 MC1330 MC1350 1741458 LM148BB LM 1489 UM 1496 ULN2003 XR2206 XR2211 1 2917 046 146 MC3373 MC3470 MC3480 MC3487 1743900 LM 3911 LM 3909 LM 3914 MC4024 MC4044 RC4136 RC4558 13600 75107 75110 75150 35154 75188 75189 75451 MCM68766 80387 20
290. uch as what most mouse and trackball drivers use Third and most impor tant you must press the button on top of the post too far to get a response and there is no feedback click to alert you when contact has been made Also the device has a separate power supply that increases cable tangle Sull because of the one to one correspondence between screen position and Felix pointer position using the device is pleasant If the device s faults are remedied Felix may well become the mouse killer it aspires to be Conclusions With so many devices on the market how does one choose among them First and foremost is how the device feels to you If the shape of your hand doesn t match that of a given pointing device you ll never feel comfortable with it Software is another priority Many pointers come with applications menu generators etc LogiTech is the winner in that category because its mouse comes with a complete text editor and also a menu generator For slightly more you can also get paint publishing and CAD programs MSC s op tical mouse also comes with a paint program and a menu generator Our personal favorite 15 the Microsoft mouse Its smal size and well formed shape feel good as do its clicky buttons In fact combined with MicroSpeed s PDA board you have an unbeatable combination ELT F apa ki ee mae Ky eh erat RECORD PLAYBACK MODULE An adaptable
291. ugh the remaining thin pieces of board on the faceplate while cutting the hole for the woofer the speaker Drill a 4 hole in each marked location Place the speaker board face down on a large flat surface to support it Drive T nut into the back of the board into each of the drilled holes Don t be concerned about the strength of the speaker panel It will be strong enough when it is glued into the enclosure with the cleats behind bonded to it However while working on other sections it may be advisable to clamp a board over the woofer hole Do not cut the port holes yet Attaching The Faceplate Now you can cut the speaker holes in the inch plywood faceplate section When cutting the woofer hole allow the saw to cut the face plate in two at the two indicated breakpoints see Fig IB After making the cut out for the tweeter round off the edges of the faceplate at the tweeter hole Glue the two faceplate pieces to the speaker board before cutting the holes for the ports Finally you will need to cut the port holes as shown The left tower should have port holes to the right of center and the right tower should have its ports to the left of center so remember to flip the pattern when cutting the port holes for the right tower If you have no way to mark and cut a perfect circle of the precise diameter needed 2 for most 2 inch I D pipe you can stencil around the pipe or even change to a port
292. until at least the next CES Price 149 95 CIRCLE 71 ON FREE INFORMATION CARD Panasonic Clock Radio If you re interested in a clock radio to have around the house there s a new one that should fit the bill literally That would be the RC 70 Clock Radio which the Panasonic Co One Panasonic Way Secaucus NJ 07094 describes as being housed in a contemporary sphere cabinet The sphere is pretty timeless but that black and white bedside model is convincingly contemporary The green LCD features a two level dimmer control and clock features include hour minute time settings a doze and sleep function radio or buzzer alarm and a power failure indicator A battery back up system keeps time internally assuring correct time display when power resumes Price 42 95 CIRCLE 72 ON FREE INFORMATION CARD Aiwa Digital Headphone AM FM Stereo Recorder Aiwa America nc 35 Oxford Dr Moonachie NJ 07074 is calling its new Digital Headphone Stereo HS J800 the first to develop an IC tuner pack incorporating digital synthesized tuning and an LCD function readout The digital readout displays radio station frequency AM FM mode tape direction and more The HS J800 features stereo recording capability and is equipped with a detachable stereo microphone There s also a one hour rechargeable battery good for up to three hours of operation Cassette features include auto reverse Dolby B noise reduction and metal normal tape selection Price
293. up remove power immediately Assuming all is okay examine LDI that LED should not be on Press the RECORD button S2 momentarily The light emitting diode will come on as long as the module is recording Speak a few words into the microphone When the LED goes off the recording period has ended Press the PLAv pushbutton switch SI and the loudspeaker will reproduce the words you have just spo ken The recording sampling rate is preset using trimmer potentiometer It is possible however to select a recording interval that is twice the preset max imum That s done by jumpering be tween terminals labeled sLow and on the circuit board For maximum flex ibility we suggest setting for a normal maximum recording interval of 5 seconds and installing a switch be tween the SLOw and COM terminals Continued on page 100 8861 390190 HANDS ON ELECTRONICS o o IDENTIFYING DEFECTIVE MOTORS Pull those broken down tape decks and defective turntables out of the closet because after reading this you ll be a motor repairman By Homer L Davidson wheel rotating the turntable whirling the compact disc or turning the drum of the VCR and where the small motor stops only the electronic technician or repair man knows At times it may be erratic and intermittent in operation Sometimes it never starts at all due to an open winding or no drive voltage And sometimes a motor prob lem
294. use a small wooden board as a chassis for the network Mount each component securely by using an adhe sive such as mounting tape or epoxy to hold it in place Point to point soldering is a suitable connection method The C1 C2 R3 4 7 12 _ _ 89 LPAD l l 511 i SPKR1 0 26mH t que 8 J C4 50 L2 ur 000005160 TO RECEIVER C39 al 3 SPKR2 4 7 0 51mH C5 24 SEE TEXT Fig 5 The crossover circuitry is simple to build and its schematic diagram is shown here The dashed box around the L pad indicates that its wiring is internal to that unit 3 4 PLYWOOD OR PARTICLE BOARD CAULKING TWEETER Fig 6 1f done with care the tweeter can be seated in the faceplate without fasteners The caulk should hold it in place Attach the foam after the caulk has dried board should be securely mounted to the cabinet floor to prevent rattling Once in place connect the driver wires to the appropriate points in the circuit Speaker polarity is important so be sure you know the polarity of the driver leads Tweeter Mounting Set each tower on its back to install the drivers Draw the tweeter cable out through the tweeter cut out and solder the leads to the tweeter lugs be sure to observe the correct polarity Run a thin bead of silicone rubber sealer around the edge of the cut out and press the tweeter into it see Fig 6 Twist the tweeter gently to make sure the sealer is evenly dispersed
295. ut in parallel Putting two equal values of resis tance in parallel gives a total resistance value of one half the value of one of the resistors The total equivalent resistance of and R2 in parallel then is 100 2 50 ohms The total resistance between A and B then is simply 50 ohms added to the value of R3 of 25 ohms for a total of 75 ohms That is the s equivalent resistance Rp Now you can connect various values of load resistance and compute the output voltage for each using Ohm s and Kirchhoff s laws Practice Problem 1 Now it s time for you to try it yourself Refer to Fig II Calculate the Thevenin s equivalent voltage and resistance R2 602 A R3 1202 Fig 11 When trying out this problem remember these steps remove the load compute the Thevenin voltage compute the Thevenin resistance connect the load to the equivalent circuit to observe its behavior You really appreciate the power and convenience of a procedure such as Thevenin s theorem when you encounter a rather complex circuit to analyze good example is the bridge circuit shown in Fig 12 All bridge circuits whether they are made with resistors or a combination of resistors capacitors inductors or transistors have four arms In gen eral most bridge circuits are balanced In other words the relationship between the resistances and or impedances of the various arms is as follows RI R2 R3 R4 So when the rati
296. ven from overseas In the old days most console and table model radios sport ed a connection for an external antenna Today very few receivers have them but you can still add an external anten na with the BC Antenna Coupler V CAN TURN AN ORDINARY AM RADIO INTO A SUPER How it Works The BC antenna coupler see Fig 1 is simply a parallel resonant circuit made up of coil Ll and capacitor Cl Signals captured by the antenna are fed to the coupler where those at the resonant frequency are passed on to the receiver s loopstick antenna coil by inductive coupling with Ll Mov ing the coupler close to the radio increases the transfer of energy while backing it off a little will help the selectivity and cut down on interference Construction Building the BC Antenna Coupler is a snap even if you ve never built an electronic project before The variable capaci tor needed for the project can be salvaged from an old radio and is mounted on its side A brass corner brace is used to secure the capacitor to a 3x l6 inch piece of wood A Fahnstock clip is placed under the screw that attaches the capacitor to the bracket FAHNSTOCK CLIP Fig 1 Believe it or not this schematic diagram contains all the components you ll need to build the BC Coupler It can be built from parts you can salvage from any old radio BC COUPLER Zoom in on those distant stations with an external antenna and you don t even have to wire it up to y
297. w Four Head VCR VT 3050 with no less than 16 screens of directions for programming the unit troubleshooting suggestions and information ranging from setting the clock to offering a toll free number for service and repair locations The data is even color coded with instructions on a green background the troubleshooting guide on a red screen and feature information on a blue screen Price 429 CIRCLE 77 ON FREE INFORMATION CARD Serpico Recreational Vehicle Alarm Sometimes recreational vehicles RVs called homes on wheels But like any homeowner RV owners are increasingly concerned with security The Serpico company 5347 Progress Bivd Bethel Pk PA 15102 is introducing a Remote Control Recreational Vehicle Alarm System RV 2 that appears to be an initial success Initial in that the firin says it features ESS electronic shock sensor IVM intelligent voltage monitoring passive infrared detec and of course an LED indicating the system status Beyond the letters the RV 2 features a 120 decibel siren and two anti scan transmitters Designed for installation by the RV owner Serpico offers a number of optional add ons to further secure the homes on wheels The system can also be used in campers delivery vehicles vans and mini trucks Price To be announced CIRCLE 78 ON FREE INFORMATION CARD Workstation Anti Glare Filters With over 15 million terminals cur
298. which category of classified advertising you wish your ad to appear For special headings there is a surcharge of 10 00 Business Opportunities For Sale Satellite Television 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 15 21 00 19 26 60 20 28 00 25 35 00 24 33 60 30 42 00 29 40 60 34 47 60 35 49 00 We accept MasterCard and Visa for payment of orders If you wish to use your credit card to pay for your ad fill in the following additional information Sorry no telephone orders can be accepted Expiration Date SIGNATURE DS 5 discount for same ad in 6 SURVEILLANCE electronics debugging kits latest high tech Catalog 2 00 TECHNOLOGY SER VICES 829 Ginette Street Gretna LA 70056 150W x 2 pre main amplifier kit or assembled dyna mite sound section tone control class A DC 78 discount if wholesale send check M O KATLI ELECTRIC P O Box 5565 Hacienda CA 91745 details send self addressed envelope PROJECTION TV Convert your TV to project 7 foot picture Results comparable to 2 500 00 proj ectors Plans and 8 lens 24 95 Professional systems available lllustrated catal
299. with a square cross section In the last case make the internal dimensions of the port 1 ya X SYo inches After cutting the holes for the ports attach a Ya inch brace across the back of the speaker board in the space between the woofer and the tweeter holes 8861 H38OL1OO D L2 Assembly with Cleats Of course you will need to cut the large sections shown in Fig 2 before proceeding further Refer back to Table 1 to determine the proper material for each section Please note that only two of the four partitions as shown in Fig 2B should have holes You will also need to cut the cleats using Table as a guide Pre drill the vertical cleats the even numbered ones for wood screws that will be used for the complete sectional assembly They will require no less than four holes each Then attach those cleats to the sides with glue and 1 inch nails see Fig 3 placing the pre drilled holes in position for later use Pre drill and install the remaining cleats on the top the partitions and the bottom Wait until the glue sets well before proceeding with the assembly of the tower Sectional Assembly When the glue has set glue and screw the bottom parti lions and top to the sides using wood screws put through the pre drilled holes Use care when matching panels so that they fit well enough to make strong air tight joints Also caulk all joints with a good grade of caulking material preferably silicone rubber
300. y Of course pointers with a bus interface need no external power source We ll note what is supplied with what in the round up that follows Microsoft It wasn t long ago that only a few companies sold pointing devices for PC s Now there are at least half a dozen includ ing two of the largest microcomputer companies Microsoft and Tandy We examined several of the more popular de vices currently on the market What follows are our observa tions on those devices The LogiTech mouse has three buttons and comes with excellent software including a complete text editor and a menu generating program that allows you to use the mouse with software your favorite word processor for example that doesn t normally allow the use of a mouse The two button Microsoft mouse is a de facto industry standard especially the underlying software interface which allows the mouse to talk to your programs For that reason most companies selling PC pointers provide software and in some cases hardware emulation of the Microsoft Mouse The mouse is available in serial which also runs on PS 2 s bus and InPort versions it is also available with various software packages Check with your dealer for the current configurations The feel of the Microsoft mouse is first rate The buttons depress easily providing a nice audible click and the mouse moves smoothly with neither jerkiness nor sliding The weakest point is the documentation You must pa
301. y an addi tional 25 for the menu generator and detailed information on the mouse function calls LogiTech The three button LogiTech mouse doesn t quite match the look and feel of the Microsoft mouse but it far outshines it in supplied software Not only does LogiTech include a menu generator and numerous menus for popular applications the company also includes programs that emulate several varieties of mice including Microsoft s and a complete mouse controlled text editor called Point Overall it is our runner up in the mouse competition bounces light off a special pad Then a pair of photodiodes detect that light providing motion information for the mouse The result is smooth reliable operation Mouse Systems Corp Formerly known as Mouse Systems Corporation MSC sells one of the few optical mice on the market today The PC Mouse has three buttons and its felt pads allow it to glide effortlessly over its 8 X IO inch pad It includes a menu generator and well written documenta including a technical reference manual Overall we like the feel of this mouse better than the Logitech but find that we can operate the Logitech and the other mice in about half the real estate occupied by the PC Mouse s pad The Manager Mouse Cordless communicates with control pod via infrared LED s Due to a sleep mode the rechargeable battery should last for several days between charges Numonics The Manager Mou
302. y inclined and are more than satis fied to simply turn on and tune in to SW signals without much interest in how their receiver works Everyone can and should be able to enjoy the radio hobby according to their own individual inter ests and aptitudes Now as to your specific question There are several sources for informa tion on buying receivers But you might want to check out the newly released 1989 edition of Passport To World Band Radio which contains specific infor mation on the most recently released SW receivers in the easy to understand format you re seeking You can find it in many major book stores Or you can order it from short wave equipment dealers advertising in Hands on Electronics or direct from its publisher Radio Database Interna tional PO Box 300 Penn s Park PA 18943 Comments Questions What are you hearing on SW Why not let us know by dropping a line as Dean did to Jensen on DXing Hands on Electronics 500 B Bi County Blvd Farmingdale NY 11735 Down the Dial Here s what others are hearing on shortwave recently How about you China 3 985 kHz Radio Beijing was noted here at 2240 UTC in English with a program about celebrating the Year of the Dragon complete with a recipe for chicken with black beans and onions Columbia 6 170 kHz La Voz de la Selva the voice of the jungle from the city of Florencia is being noted with Spanish language programming time checks c
303. ynthesizer the transmit data TD line normally line 2 and the signal ground normally line 7 When a dumb terminal or equivalent is used lines 2 and 3 on the RS 232 connector should be tied together so that what you type will appear on the terminal s screen The CTS256 AL2 is an eight bit microprocessor with let ter to sound rules programmed internally in ROM A pin out diagram of that integrated circuit is shown in Fig 1 Those built in rules allow for translation of ASCII letters and num bers into allophones that are compatible with the 5 0256 AL2 speech processor To determine proper pronunciation the CTS256 AL2 looks at the placement of the character in relation to the characters that appear before and after According to the device s data sheet the text to speech converter is about 85 accurate as far as the proper pronun ciation of the word was a bit skeptical of that estimate at first However after breadboarding and testing the circuit 1 found the 85 figure to be quite accurate I also found that any word could be made to sound correctly if it were spelled phonetically instead of properly For example If you enter the B5 R W Veg B7 CLOCKOUT B6 ENABLE 80 BA ALATCH B1 AE SCLOCK AS RXD XTAL2 CLOCKIN 1 07 06 CTS256 AL2 Fig 1 This is a pin out diagram of the CTS256 AL2 text to speech converter integrated circuit That device takes the ASCII serial output from a computer or dumb terminal and

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