To OSCILLATOR - World Radio History

December 1993 Heap*Vol. 64 No. 12ON THE COVERCould you use "eyes in the backof your head" around your home oroffice? Perhaps a surveillancecamera would be a sensible addition to your home -security system, or you'd feel reassured byputting a video baby monitor inthe nursery. If you haven't in-stalled such systems becauseyou've been put off by the thoughtof the time and expense involved,1-11r.314TECHXMASnow's the time to do it-with ourMini TV Transmitter. When usedwith one of today's reasonablypriced, palm- sized, solid -statevideo cameras, the Mini TVTransmitter can send black -andwhite pictures from remote locations to your TV set. No cables arerequired, and if the TV is nearby,no antenna is needed either. Forall the details, turn to page 29.AUDIO SCRAMBLINGSYSTEM.fÂîiAMEpIT SAdd an electronics theme to yourChristmas decorating withthe Visible Components.4atTawd eswadroPOóf M sasmóknd dewrtiitsyour hansher ratnoroatlotw.MANY IN117410 MODOIJK ONOáaWm how to sae the phoasrosbt msfhadfor makk year own PC bawds.psiWdaa.PAGE 33PAGE 37.é:g.m.,.PAGE 43As a service to readers, ELECTRONICS NOW publishes available plans or information relating to newsworthy products, techniques and scientific and technological developments.Because of possible variances in the quality and condition of materials and workmanship used by readers, ELECTRONICS NOW disclaims any responsibility for the safe and properfunctioning of reader-built projects based upon or from plans or information published in this magazine.Since some of the equipment and circuitry described in ELECTRONICS NOW may relate to or be covered by U.S. patents, ELECTRONICS NOW disclaims any liability for the infringementof such patents by the making, using, or selling of any such equipment or circuitry, and suggests that anyone interested in such projects consult a patent attorney.ELECTRONICS NOW, (ISSN 1067.9294) November 1993. Published monthly by Gernsback Publications, Inc., 500 -B Bi -County Boulevard, Farmingdale, NY 11735. Second -Class Postagepaid at Farmingdale, NY and additional mailing offices. Second-Class mail registration No. 9242, authorized at Mississauga, Canada. One -year subscription rate U.S.A. and possessions 19.97, Canada 27.79 (includes G.S.T. Canadian Goods and Services Tax, Registration No. R125166280), all other countries 28.97. All subscription orders payable in U.S.A. funds only,via international postal money order or check drawn on a U.S.A. bank. Single copies 3.50. 1993 by Gernsback Publications, Inc. All rights reserved. Printed in U.S.A.POSTMASTER: Please send address changes to ELECTRONICS NOW, Subscription Dept, Box 55115, Boulder, CO 8032t -5115.A stamped self- addressed envelope must accompany all submitted manuscripts and /or artwork or photographs if their return is desired should they be rejected. We disclaim anyion or otherwise.responsibility for the loss or damage of manuscripts and/or artwork or photographs while in our pPLEASE TURN PAGE FOR COMPLETE CONTENTS

1,4,FP1ElectronicsNOW4111-::)29 MICRO TV TRANSMITTERSendapicture to your TV with this wireless miniature TV transmitter.Martin McKinney and Garnet Brace33 HIGH -TECH XMAS ORNAMENTSBrighten your holiday decor with the Visible Components.Ron Holzwarth37 AUDIO SCRAMBLING SYSTEMScramble your phone conversations to prevent eavesdropping.William Sheets and Rudolf F. Graf66 STATIC ROMBuild our inexpensive EPROM emulator to help with microcontrollerdesign.Fred EadyHugo Gernsback (1884.1967) founderLarry Steckler,EHF CET,editor -in -chief and publisherEDITORIAL DEPARTMENTBrian C. Fenton, editorMarc Spiwak, associate edito,Neil Sclater, associate editorTeri Scaduto, assistant editorJeffrey K. Holtzmancomputer editorRobert Grossblatt, circuits editorLarry Klein, audio editorDavid Lachenbruchcontributing editorDon Lancastercontributing editorEvelyn Rose, editorial assistantTECHNOLOGART DEPARTMENTAndre Duzant, art directInjae Lee, illustratorRussell C. Truelson, illustrati z,,43 THE PHOTORESIST METHODHow to make professional -quality circuit boards at home.John Bercik48 OSCILLATORSPRODUCTION DEPARTMENTRuby M. Yee, production directorKaren S. Brownadvertising productionAll about transistor oscillators and multivibrators.Ray Marston58 THE LOST ART OF REGENERATIONClassic regenerative receivers and their modern, transistorizedversions.Kathryn R. Campbellproduction assistantLisa Rachowitzeditorial productionCIRCULATION DEPARTMENTJacqueline P. Cheesebocirculation directorCharles KitchenWendy Alankocirculation analystTheresa LombardoRTM12 VIDEO NEWSWhat's new in this fast changing field.David Lachenbruch18 EQUIPMENT REPORTSInteractive ImageTechnologies ElectronicsWorkbench82 DRAWING BOARDPlay our game without thecirculation assistantMichele Torrillo72 HARDWARE HACKERDigital photo imaging, andmore.Don Lancaster80 AUDIO UPDATECable conflicts.Larry Klein84 COMPUTERCONNECTIONSThe holy grail of the computerdocument check.industry.Robert GrossblattJeff Holtzmanreprint bookstoreTypography by Mates GraphicsCover artwork by David WinsloVideo University GraphicsElectronics NowApplied Science&is indexedand Readers Guide to Periodical Literature, Academic Abstracts, andMagazine Article Summaries.Microfilm&Microfiche editions areavailable. Contact circulation depart.,ment for details.Advertising Sales Offices liston page 98.Electronics Now Executive andAdministrative Offices1-516- 293.3000.Subscriber Customer Service:1- 800.98 Advertising Sales4Offices98 Advertising Index93 Buyer's Mart16 Letters288 -0652.Order Entry for New Subscribers,"1. 800 -999.7139.26 New Lit23 New Products14 Q&A6 What's NewsiTechnology IndeAudit Bureauof CirculationsMember

TURN A FAULTY VCRINTO A PROFIT!66 . gives all the necessary information for learning the art of troubleshooting popular brands.99-ElectronicsFor YouCA. . fully explains the mechanical systems andelectronic circuitry. also details servicing data on-VIDEO Magazineall popular brands of VCRs.Newly revised, MAINTAINING AND REPAIRING VCRs is the ONEbook no electronics activist should be without. It gives you theoperational specifications, testing how -tos, repair procedures,and troubleshooting techniques used by top professionals inthe field. This is the information you need to quickly pinpointany malfunction and fix it right down to the component level.Packed with hundreds of helpful pinout diagrams andexploded -view illustrations, MAINTAINING AND REPAIRING VCRsgives you the how -tos needed to tackle even the trickiest VCR,Beta, or camcorder repairs. Now, there's, no need to spend hourslooking through service literature, and using trial and error.Everything you need to turn a broken VCR into cash in yourpocket is here in MAINTAINING AND REPAIRING VCRs.Turn to Bob Goodman for expert adviceBob Goodman explains the test equipment you need, the pro-cedures you follow, what circuits work best where, and thevarious repair options you have. lie walks you through everyservice, maintenance and repair you make, giving you actualcase problems, symptoms to watch for, and solutions for each.See for yourself how easy it is to make successful VCR repairs, andprofit from that success.FREE UNIVERSAL TEST LEAD KIT WITHEVERY ORDER!'.,00,.,,J1. Call1-800-822-815814-2.FAX3.Or mail this coupon to:TAB /McGraw -Hill Inc.Blue Ridge Summit, PA1- 717 -794 -208017294-0840457 illustrations520 pages 39.95#023969-XHStep -by -step, MAINTAINING AND REPAIRINGVCRs will help you master maintenance andrepair procedures, including how to:Adjust belt and drive wheelsReplace audio and video headsFix damaged or weak control functionsMinimize damage caused bycontaminantsRepair and replace dirty switch contactsTroubleshoot electronic or mechanicalservo malfunctionsIdentify and correct video head stickingand frictionTurn a snowy, weak picture into a crisp,strong pictureAdjust an improperly running tape pathAnd much more.Includes 14 electronic tools that you can use to test and measure equipusescrew on alligator clips for groundingment. Use this kit tofind where your current is comingprobes to check for defectsand more.measure voltagefrom3 Easy Ways to Order:(24 hours a day, 7 days a week)FREE GIFTWITH EVERY ORDER!Please Cut Along Dotted LineYES,send me MAINTAINING AND REPAIRING VCRs -3rd Ed.(#023969 -XH) to examine FREE for 30 days. After 30 days, I will pay 39.95plus postage, handling, and applicable state and local sales tax. If I amnot completely satisfied, I can return the guide and owe Order invalid without signatureOrder subject to credit approval and acceptance by McGraw -Hill. Prices subject tothe U.S. and Canada must be prepaid in U.S. dollarsoutsidechange. Orders madedrawn on U.S. banks, and include an additional 5.00 postage and handling.SP93EN15

A review of the latest happenings in electronics.Smart Card Forumaccelerate the use of SmartCard technology, representatives ofthe telecommunications, entertainment, software, publishing, computer, health -care, and financial -services industries have banded withgovernment agencies to form theSmart Card Forum. The Forum'sgoals are to address compatibilityToissues across business applications, and to facilitate the markettests of multiple -use cards. A technology committee will provide advice on technology, systems,security, and interoperability issuesto the various business -applicationscommittees.Smart Card technology was invented in 1975 and has been usedsuccessfully throughout Europe andAsia in banking and telecommunications applications. Prepaid cards"contain" digitized money that canbe used as cash wherever a SmartCard reader is available. It is predicted that by 1995 more than 1.25billion Smart Cards will be issuedworldwide for such purposes asmaking phone calls, paying tolls,paying bus or subway fares, andbuying convenience items.The Forum is open to pubic andprivate- sector organizations with auser- or business -applicationsfocus. Various categories of membership, with fees ranging from 1000 to 15,000, are available. Formembership information, contact800 -393 -6786 (813- 286 -2339 outside the U.S.).Robot Contest6The Science Center of Connecticut is sponsoring the InternationalRobot Contest on Sunday, April 17,1994. The day -long event will be theculmination of a four-month roboticsexhibit at the Science Center. Thecontest is open to everyone and hasdifferent categories to allow peopleof various ages and experience levels to compete. All entrants will receive an award. The top winner willreceive a 1000 check and additional prizes will be awarded to otherwinners.The challenge is to build a roboticdevice that can move through amodel of a single floor of a house(measuring 8 x 8 feet and divided bywalls, hallways, and rooms), look forfire (a lighted candle), and extinguish it. The robot that completesthose tasks in the shortest amountof time will win. Robots must be lessthan one foot on a side and can betethered to a personal computer orcontrolled by a built -in microprocessor.Anyone who is interested in competing can receive the completerules of the contest along with theexact layout of the model house, bycontacting Jake Mendelssohn, Science Center of Connecticut, 950Trout Brook Drive, West Hartford,CT 06119; Phone: 203 -231 -2824,extension 46; Fax: 203 -232 -0705;Prodigy: KJRP71A.Amateur TV awardsprogramAmateur Television Quarterly of-fers an award program for TVDX'ers. TV Quest is open to hamsand SWL's who engage in two -wayor one -way TV activity. Certificatesare awarded to those who receiveham or commercial television stations from long distances (in 100 mile increments starting at 100miles), and to those who catch aspecific quantity of stations (starting at 25).Upon joining TV Quest, hams receive a certificate of membershipimprinted with their call sign and apersonalized Q number; non -hamsare assigned a Q number for SWLpurposes. The colorful DX QuestAward for distance and QuantumAward for number of stations areboth suitable for framing. Figureshows a sample award.Subscribers to Amateur Television Quarterly receive automaticmembership; non -subscribers can1P- i-J'ñ jAMATEUR TELEVISION QUANTUMAWARDKB9FOVfEHAS SUCCESSFULVTRANSMITTED AND RECEIV DVIDEO SIGNALS FROMs.'.50FIG.1-ASAMPLE QUANTUM AWARDcertificate.joint the Quest TV Society for amodest fee. Only contacts and stations received after October 1, 1993count toward the certificates. Forinformation, send a self- addressed,stamped envelope to ATV Quest,1545 Lee Street, Des Plaines, IL60018.Digital video compact discsThe basic specifications of the"Video CD" format, as well as alogo mark that signifies hardwareand software compatibility based onthe format, have been establishedby Matsushita, Philips, Sony, andVictor Company of Japan, Ltd.(JVC). The Video CD is based onthe Karaoke CD format that wasestablished as a standard in March1993 by JVC and Philips and whichis already well established in Japan's professional karaoke market.The format has the capability tostore 74 minutes of audio and digitalfull- motion pictures ona 12 -cmcompact disc. It is based on theMPEG -1 standard.The four companies have agreedto include in the Video CD formattwo optional features: two levels(normal and high resolution) of stillpicture playback functions and playback control. The optional functionsare expected to broaden thenumber of possible applications,particularly in education, training,and information.Hardware and software manufacturers have begun to apply the Video CD format to a range ofapplications including movies, mu-

The Meter to PickWhen You HaveThings to Fixsic, and educational programs. Video CD discs will play on a variety ofvideo products, such as Video CDplayers, CD -I players equipped withdigital -video cartridges, computerswith CD -ROM drives and MPEGdecoders, and CD players (with adigital data output) with an add -onVideo CD adapter. Licensing will beavailable worldwide.No Other DMMMakes So ManyCommunity informationnetworkMeasurementsZenith's "information highway" isintended to support a range of interactive applications, including work at -home and electronic resourceservices and distance learning.HomeWorks also supports computing needs for health -care, legal, andfinancial businesses. Selecting aservice will be as easy as tuning in atelevision channel.The HomeWorks system consists of a PC gateway card and external RF modern that transmits andreceives on standard cable -TVchannels, sharing the cable with video channels. It transmits at 0.5megabits per second, significantlyfaster than telephone modems andISDN. Four 0.5 -Mbps sub -networks can be configured on a single6 -MHz cable-TV channel for an aggregate data rate of 2 Mbps. Thegateway card provides softwaredriver support for many popular network operating systems, includingNovell (PX and ODI), MicrosoftNDIS, TCP/IP, and IBM NetBIOS.The HomeWorks model PCTV-R isi2available for less than 500.o .* ti VOLTAGE cm o ,çm'4z,eètN.,a c,'ÊONo y ,1CURRENTDigital ReadoutBacklit 4 -digit display with bignumerals (17mm, 5/8').111,1,1Analog Bar GraphSimulates an analog meter to indicatetrends and changes.VVVVVProbe Hold''Store your last stable reading for later;allows safer meter operation becauseyou can keep your eyes on your work.(LAN) gateway-called "Home Works" -will offer cost -effectiveconnectivity over standard cable TV home- subscriber facilities.data.e soSo Many Ways!Zenith Electronics Corporation(Glenview, IL) introduced an innovative interface for personal computers and cable television systemsat INTEROP '93 in San Francisco.Part of its growing MetropolitanCommunity Network strategy, theresidential PC local area networkHomeWorks provides a multimediacommunications conduit that allowsLAN data to be transmitted on fiberoptic or coaxial cable and coexistwith other services, such as video,manufacturing networks, video teleconferencing, and point -to -pointo 4,s0Peak Hold'"Measure and store peaks as short as1 ms. Detect transients, measure inrushcurrents, and determine crest factors.Auto Min Maxim with Averaging VVVVVVVVRecord the minimum, the maximumand the average reading, unattended.Fully autoranging for maximumVVVVVVVVVVVVresolution.VReITM Relative ModeRead the difference between thepresent and previously stored values.Fully autoranging for maximumAutoVV V VVVVVresolution.VVVVIntermittent DetectorLocate intermittents, broken wires,loose connections quickly and easily.Once you've used Wavetek's exclusiveFault Finder "", you'll never want to be,without it.171801LtJ. oLr.L oÍ,r.I.a.Lr.The Wavetek Model 2030 DMM is packedLr.4a, Í,eÌwith powerful tools for tough troubleshooting jobs. The exclusive Fault Finderpinpoints intermittents faster than any other multi meter. Memory modes can store readings whileyour hands and eyes are busy. True rms, as wellas peak readings,help hunt down damagingpower harmonics.And there's a big, 10,000 -count backlit display, and an easy-to -use MENU system thatlets you jump between all these capabilitieswithout having to drag out the manual.The Wavetek 2030. It's the one meteryou'll choose when it's time tofix something.AAskMADE IN U.S.A.Wavetek Corporation9145 Balboa AvenueSan Diego, CA 92123(800) 854-2708WAveTa K(619) 279-220001'93 Wavetek (,rporan,.nCIRCLE 98 ON FREE INFORMATION CARD7

No other trainingto troth1eshoócomputerYOnly NRI walks you throughDISCOVERY LABComplete breadboarding systemDIAGNOSTIC HARDWAREthe step-by -step assembly oflets you design and modifyAND SOFTWAREcircuits, diagnose and repair faultsR.A.C.E.R. plug -in diagnostica powerful 486sx computercard and QuickTech menuLESSONSdrivensoftware,bothfromsystem you train with andClear, illustrated texts486sx/25 MHzUltra -X, give you hands-onbuild your understandingexperience with today'skeep -giving you the hands of computers step by stepprofessional diagnostic toolsMini -Toweron experience you need toMONITORComputer!High- resolution, nonglare,work with, troubleshoot, andI4" TTL monochromemonitor with tilt and swivelservice today's most widelybaseDIGITALused computer systems. OnlyLOGIC PROBESimplifies analyzing digitalNRI gives you everything you need to startcircuit operationDIGITALa money- making career, even a businessMULTIMETERProfessional test instrument forof your own, in computer service.quick andNEW!-easy measurementsNo doubt about it: The best way to learn to servicecomputers is to actually build a state-of-the -artcomputer from the keyboard on up. Only NRI, theleader in career -building at-home electronics trainingfor more than 75 years, gives you that kind ofpractical, real-world computer servicing experience.Indeed, no other training -in school, on the job,anywhere -shows you how to troubleshoot andservice computers like NRI.SOFTWARETrain with MS-DOS andpopular Microsoft Worksapplications software41Get inside a state -of- the -art 486sxcomputer system. and experienceall the power and speed oftoday's computer technology!With NRI's exclusive hands -ontraining, you actually build andkeep a powerful 486sx/25 MHzmini-tower computer system.You start by assembling andtesting your computer's 101 -key"intelligent" keyboard, move onto test the circuitry of the mainlogic board, install the powersupply and 1.2 meg high-densityfloppy disk drive, then interfaceyour high-resolution monitor.What's more, you now go onto install and test a powerful 80meg IDE hard disk drive- today'smost -wanted computer peripheral- included in your course todramatically increase your computer's data storage capacitywhile giving you lightning quick data access. But that'snot all!Professional diagnostichardware and softwaremake troubleshootingfast and accurateYour NRI training now includesa

See your Fluke distributor, or call 1- 800 -87 -FLUKE for a catalog and the name of the distributor nearest you. in the industry. Make the choice that gives you the most choices. Fluke 12 Auto -function Multimeter S95.00 FLUKE 12 FLUKE 77 FLUKE 83 The Fluke