I JULY1992 mill ii^mm mimtmix Use your portable CD player in your car wHh our high-quality, easy-to-build transmitter Add a frequency counter and capacitance meter to your PC Our cranking amp estimator will make sure you don't get stranded on the road by aweak battery! Combing with Wectrnm K5 V-\\ How to use photosensitive devices ih your designs What the World Administrative Radio Conference means to you 0 7 09128''48783""o $2.95 U.S. $3.75 CAN GERNSBACK Keep your sensitive data out of other people's hands! ^x.xx:xxt:%x CAR-RT SORT CRUJ r5D45GHRR5 16511093 D7 S9 NDU 93 RE X 53151 The Fluke 79: More Of A Good Thing More high-performance features. More advanced measurement capa- bilittes. More of the vital Information you need to troubteshoot even the loughest problems — wilh both ana- log and digilal displays, f\/leenhe latest, greatest member of our best selling 70 Series II family — the new Fluke 79 digilal multimeter. It picks up where the original fam- ily left off. In fact, it's a quantum leap forward — in performance, value and affordability. It's got the features you^d expect from Fiuke. Including high resolution. Fast autoranging. Patented, automatic Touch Hold\ A quick continuity beeper. Diode test. Automatic self- test. Battery-conserving sEeep mode. And it's just as rugged and reliable as the rest of the 70 Series II family. Easy to operate, too — with one hand. And thanks to the Fluke 79's proprietary new integrated circuit technology, that's onty the beginning. When it comes to zeroing in on tough electrical problems, the Fluke 79 leaves the competition behind: Hz Frequency: The Fluke buil-in frequency counter you measure Uom thelow 1 Hz to over 20 kHz. And while you vlevif Irequency on the tfigitat display, the analog bar graph shows yoD AC voltage. So you can see if potentially haiandous vollaoe is present. Fast 63'Seonienl analog bar graph: The Fluke 79's tjargraph moves as fast as I he eye can see, updating at a rate ol 40 times per second to simulate the functionality of an analog needle. You get the high speed j/rtf high resoltiiian you need to detect peaking, nulling and trending. He Capacitancfl: No need to cafry a separate dedicated capacitance tester; the Fluke 79 measures capacitance trom 10 pF to 9999 jiF. m ^1 H n^F mV AC mV DC A 0 ^imumjiimiiuiiiaiiiiiiiiiiiHiiiiiiJifiiiiin^ 0 400: Actuat Size Lt-Ohms range: Gur proprietary Lo-Ohms function lets you measure resistance as low as 0.01 ohms High noise reiection and a test lead Zero Calibration function make the Fluke 79 ideal tor detecting small resistance changes. SMOOTHING Smoothing^": Our exclusive new Smoothing mode gives you a stable digital readout for unstable signals — by displaying the running ■average of eight readings. No more jitter or ''digit rattle'' due to noisy signals. Geta good Ihing going: To put more meter to work for you — at a price that works for you, too — head for you nearest Fluke distributor For the name of your nearest distributor, or for more product information, call 1-80Q-87-FLUKE. The Fluke 79 comes with a yeJIow holster and palenEed Fi ex- Stand ' — easy lo hang from a door or pipe, clip onto a bell orloo^ kst, or stand at virlually any viewing angle. There's even slorage space for test leads Flufce 79 Series II siar 430DC«unt DigiUI Oi^ii^ i9999 m H/ ind Lo-Oliins> C 3 ' = 3? 5 ic DC vmQt A^cuiicy AuiamaEic Touch Moid Oio^jt Tesl, Aud.bk CanTrnufty Setper /imor2nq\r--q. Manual Ranging HolslcT v/\th Fles-S!and Ff Ktuencjf Counlei to ovf r ?e kHi CapjciiancB. 1 0 fo jjf 700 rt=Mrs SaTleiy lj!e [jikjshihii FLUKE AND rUlLIPS THE T £i M ALLIANCE J ah n Fru ke Mtg. Cs. , 1 nc P 0 fiojt mQ . WS 2 m Everen. WA 53?06. € Copynorit 1991. Prices anfl specificaEions subject to change wilhotjt whet Ad nn 001 72. FLUKE CIRCLE 121 ON FREE INFORMATION CARD July 1992 Bectrmcs Voi. 63 No. 7 33 FM STEREO BROADCASTER Transmit line-level audio distances of up to 60 feet with this easy-to- buitd device. Luther M. Stroud, CET, N5TVY 57 CAR BATTERY TESTER This high-tech tester will let you know the conditon of your car's hattery. Thomas R. Fox pt; PASSWORD PRQTECTIQN 41 PC BASED TEST BENCH Build the 11 001 and get a frequency counter, an event/period meter, and a capacitance meter Steve Wolfe 51 PC PASSWORD PROTECTION Add password boot protection to your PC, Mark Hatten CAR BAHERY TESTER 38 WARC '92: RF SPECTRUM PREPPED FOR NEXT CENTURY A look at the 1992 World Administrative Radio Conference. Stanley Leinwoll 63 PHOTOSENSITIVE DEVICES Put photoconductive cells^ photodiodes, and phototransistors to use in your projects. Ray M, Marston PAGE 57 8 VIDEO NEWS What*s new in this fast- changing field. David Lachenbruch 20 EQUIPMENT REPORT Paragon LA16PC 75 HARDWARE HACKER Dye- based solar energy. Don Lancaster 82 AUDIO UPDATE The kit era passes. Larry Klein 88 DRAWING BOARD Finishing the scope. Robert Grossblatt 90 COMPUTER CONNECTIONS The virtual PC. Jeff Holtzman 102 Advertising and Sales Offices 102 Advertising Index 10 Ask R E 93 Buyer's Market 4 Editorial 12 LeHers 30 New Lit 22 New Products 6 What's News m 1 c 9 I UJ There's no doubt that weVe all be- come spoiled when it comes to mu- sic — we're used to having music where ever we go. But what liappens if you feei Hke listening to a CD in your AM/FM/cassette-e quipped car? Or when youVa mowing the lawn but your personal portable can't pick up your favorite radio sta- tion? That's when our FM Stereo Broadcaster comes in handy. The versatile transmitter can take music from any line-level audio source and broadcast it anywhere within a 50 foot range. You can send audio from a portable CD player to your car ster- eo, or from your home stereo to your Walkman. Take a look at the project on page 33, and see how many other uses you can think of! EI THE AUGUST ISSUE GOES ON SALE JULY 7. BUILD AN ATV TRANSMITTER Complete construction details for an amateur television trasmitter. BUILD A TELEPHONE VOICE SCRAMBLER Keep your phone conversations private! NOTWORKING TO NETWORKING An introduction to the hardware basics and benefits of LAN's. PC-BASED TEST BENCH Build an A/D converter that can be used as a low-frequency oscilloscope. As a service to readers. ELECTRONICS NOV publishes available plans or informaUori relating to newsworthy products, techniques and scientrfic ar>d tochnalogrcrtl deveEopnients.. Because of possiil^i^e variBnces in the quality and condition of malorinU and workm^tnship used by rniiders, ELECTRON ICS NOW disclaim a any ffl^poasibility for the safe and proper funcUoning of raader-built pjisjects basvd upo-n cr IrDm plans ormfgrmation pubtlgh^d in this magarme. Sincfl Si^me of the equipment and circuitry dfiiUfribed \n ELECTROhJfCS NCWmay rvlato to nr be covered by U.S^ pjitvnta, ELECTRONICS NCW discbim^ any liability for the infringement of :such patents by the making, using, or seUing of any luch equipment or circuitry, and suggests that anyone interested in such projects coniull ^ p^itent attorney, ELECTRONICS NOW, fiSSN 0033 766?) Julv 1992 PobFished monthly by Gernsback Publications, Int . 500 B Bi Co unN Boulnv^rd, Farrningdala, NY 11735, Second 'CFass Po&tage paid at Farnii-ng.dile. and additional mailing offices. Second- Class marl registralion No- R1251662SCI. authoriiad at To^onio. Canada. One year subscription rale U-S A. and possessions $17.97. Canada 32!i.&S (incEudcs G ST. Canadian Goods and Services Ia« l^egistratfon No, R123166230), all other countries &2G.97. All subscrcption orders ^yable i:n U S-A. fkjods only, vj# international postal n^onoy order or check drawn on a U,S-A. bank. Single copies ^2,95. '-r 13^92 by Gernsback Publicattonsn Inc. At! rights resarvwd. Printed in USA- PQSTM ASTER: Rease send address chanaes to ELECTRONICS HOH. Sut^crlption 0«pL. Box Bojlder. CO S0321 5115, A stamped self- addressed envqlopo must accompany all submitteci rtiana^^cripts JM>d/or artwork or photographs if theif return -is deaireu should the^ be rejected. We disci Him any responsibi^lity far the Foss or damage of rn an u scripts and/or artwork or pholographs while in our possesiton or o1h9rwlse- BBOmics Hugo Gern ^ back i \ 864- 1 @67^ f au nder Larry SteckFer, EHR GET, editor-in-chief and pubEfshef EDlTOtllAL D£PARTMEI^T Brian C, Fentorii editoT Marc Spiwak, associate editor Neil SclatoTf associate editor Teri Scaduto, assi^stdnt cdttor Jeffrey K, Holtziriiin computer editor Robert Qrci9Sblatl» circuits editor Larry KletHf audio editor David Lachenbruch corflributmg editor Don Lancaster contHhuttng editor Kathy Teren^, ^dUorial assistant ART DEPARTMENT Andre OtJiCfiriti art director Injae iltustrntor ftu«$eil O- Truslflon, illustrator FRDDUCTtON DEPARTMENT Ruby M. Yoe^t production di lector Karen S. Brown advertising production Marcella Amoroso production assistant Lisa Rachovvitz oditonal productton CtRCULATlON DEPARTMENT 4ac and Magnavox CATV Systems CManlius. NYX The system depends on a ghost cancellation reference CGCR) signal that eliminates moving ghosts as well as ghosts in weak- signal and noisy reception areas. The GCR signal is sent during the blanked portion of the TV raster When it reaches the receiver, the reference signal has undergone the same ghosting distortions as the TV picture. A processor integrated circuit analyzes the distortions and calcu- lates con^ctions. and filter ICs per- form cancellation. Two generations of ghost filter chips capable of can- celing many stnang ghosts sinmulta- neously have been developed. The first generation filter chips are being produced by VLSI Technology, Sec- ond-generation chips, jointly de- signed by TLW, a Boston consulting firm, and Hewlett-Packard, are being manyfactufBd by HP. The system also includes a pro- 1 — = =1 PHILIPS VI DEO G HOST CANCELLER for television sets (center) ellmrnates the ghosts that appear on TV screen at left so they look like the sharp picture at right. totype Philips deghoster firmware that was found to be reliable in NAB s tests. Philips' scientists de- veloped mathematical algorithms and processing software to control the hardware. The Advanced Television Sys* tems Committee is scheduled to select the standard GCR for the United States in a few months. Meanwhile, Philips Consumer Elec- tronics Company and Magnavox are working to include the Philips Ghost Canceliation System in their Philips, Magnavox, and Sylvania color TV receivers. Magnavox CATV Sys- tems will begin selling the VECTOR video echo canceler in May. Ac- cording to Magnavox CATV, it will provide ghost^free TV reception for cable TV subscribers. Digital tnajor^eague broadcast CBS Radio broadcast the Gincin- nati Reds' opening game at Riverfront Stadium to start its t7th season of Game of the Week coverage. However, this time there was a difference: advanced digital broadcast technology was tried. The result was crisper sound for the fans and a large savings for CBS. Traditional satellite and long-dis- tance voice circuits require an on- site satellite truck, an army of tech- nicians, and as many as four satel- lites to complete the long-distance feeds between New York and the stadium. AH this costs about $2500 per feed. By contrast, the new CBS approach depends on on MCI Com- municdtions Switched 56 full-du- plex digital service for transmission of its bnDadcasts from major league ball parks around the country to its New York facilities. The an- nouncer's voice is digitized and compressed before it is sent over MCls digital network at about the same cost as a regular phone calL Switched 56 circuits are installed at each of the major league ball- Continued on page 50 ASAP • JIT • MRP OUR DISTRIBUTORS HELP ABBREVIATE YOUR PROCUREMENT CYCLE! AewM^hc Aerovoc- CAROL AV>>:( OORPORAnON 1 BURIMDY Bussmann INtXJSmiES. INC Phofx, SoADcr 3l Ii C lubbft^ Soa^ Bunpcn Du Pont Connector Systems it) XOaV speer electronics, inc. Lalon CoTpotaUou, Commercial A Miliury ConlFaU (Iprniliiin 4 GERMSBACK PUBLtCATlON GENERAL DEVICES tnlitan. !«)rT TmliJiiiii €apj|'ibm IrnlndiHlt KEMET Bt^tf^CS Corpofsiion Solid tkntalum. MuEii U^rr Cetutilf , ind Surfict MouiK A COMMNV OF CljUCtlan.Tfl Afdtl North ilmerican Capacltuf t:tjmp3Jiy Cmaiict. Fliioi. ^C'l ■nd If t fittrfi PKilips ECG A North Arrw^cfln Phlllpn Company^ SntilconduiL'liir^. ItW fijuJpmfiit, SwMchcrart •^Manhattan' □tarlaJ v\i Ekciicmlc isi'lfr, Cibk and Dinnrilor^ mii/Ztiiafiina OsdUxtorr PoiCTVtlcimetifti, l>1^£MI f\\\tn. NTE ELEXTKONitf;, Inc. Ol la m Roederstein ^^^^^ ^JiHHpriiiifn ini iitiudiiai tJiHtfialiMt (Jj(iu1ltifi, ind Artiiiitri Thomson Consumer Electronics^ Inc, l^t^im^mm ptn* m ica ui4 Til Whenever you need electronic products* make your initial call to a distributor. Distributors help speed up your time to market, providing the convenience, the economy, the value, and above all, the service that helps make you competitive. The sponsors of this message know how important it is — to us and to your MRP — to get product ASAP or JIT Another important abbnrviation is EIA, Our participation in the Electronic Industries Association's Components Group makes us all more competitive, through fostering better working relations and coherent industry standards, and through the sharing of ideas to help both buyers and sellers. In choosing your component supplier, look for the marks of leadership — availability through distribution and memlxTship in the ElA, Eiectronie Industries Association /Components Group 2C01 EVnmvlvaiua Avenue^ N.W. {\ih Floor Washingrcirt, DC 20CO6 Ptionci (202) 4574930 Fiwt: (202)457-4985 CiiJi«mifE«i fo iht ampemtx^em^ &[ ih^ VIDEO NEWS WhaVs new in the fast-changing video industry. DAVID LACHENBRUCH • Movies on CD's. In a little- noted but historic event last March, Philips demonstrated full-nnotron video of at least VHS quality on a standard compact disc. Spectators at the International ConFefence and Exposition on Multimedia and CD- ROM in San Francisco gasped at the quality of the moving images presented in the CD- Interactive CCD*!) demonstration. Philips, which is now selling CD-I players and discs without full motion, hinted that the future discs could ultimately be used for movies, music video, and full* motion games in the home. The CD-I players currently being sold in the United States ane de- signed to accept a piug-in adaptor for full-motion video, which is due late this year, at an unannounced price, and the next model CD-I play- er is expected to have full motion built in. Because the maximum play- ing time of a CD fs 72 minutes, the CD-I's application as a movie medi- um would depend on the future in- troduction of a CD-I changer. That product is believed to be under de- velopment. but Philips won't com- ment on that project. • HDTV landmark. The first live, ovepthe-air broadcast of a digital high-definition TV system was re- ceived in the United States Capitol Building, fitting for the momentous occasion. The system. DigiCipher developed by General Instrument and MIT. is one of hve systems being evaluated by the FCC's Ad- gj vanced TV Advisory Committee. ^ The signal originated at WETA-TV, ^ V^shington s Public TV station, op^ g erating at about 2% of the station's 2 normal power One prime require- 8 ment for digital TV is low- power 1 transmission. ^ The station broadcast a pre* ^ recorded program from a high-defi- nition tape player. In the audience at the Capitol were about 50 people, including Speaker of the House a Foley and four FCC commissioners. They viewed the broadcast on a 65- inch Hitachi projection set and two 28'inch Sony direct-view monitors. The broadcast was also suc- cessfully carried by the Capitol Hill Cable System. The demonstration proved that digital HDTV broadcast* ing is feasible. The other three pro* posed digital HDTV systems have been demonstrated in prototype closed-circuit operation, but not in on-the-air broadcasts. DigiCipher was the first digital HDTV system to be tested by the Advanced TV Test Center in prior to an FCC decision, • The timetable slips* There was bad as well as good news on the HDTV front. In an interim report, the FCC s Adx^nced TV Advisory Committee said that the timetable for testing proposed systems by the Advanced TV Test Center had slipped by more than four months. Under the new timetable the com- mittee plans to recommend the win- ning system, based on its lab tests, by eariy February 1 993. The decison had been originally scheduled for September 30. 1992. The system that peri^orms best in the test cen- ter's lab tests will be field tested in an actuai broadcast from Chariottep NC. Field testing is expected to be complete by June of 1993. The njn- ner-up system will also be field test- ed if problems develop with the winning system. The FCC will make its decision shortly thereafter • HDTV sets — how soon? FCC Chairman Alfred Sikes fore- cast that despite slippage in its test- ing timetable, the public will be able to buy HDTV sets between mid-1995 and mid- 1996. But the question of when and how much still remains hotly debated. Roy Pollack of Ford ham University formerly ex- ecutive vice president at RCA in charge of its electronics business^ told a recent seminar that such fore* casts are "an unfortunate example of hype and wishful thinking." Sol- omon Buchsbaum. senior vice pres- ident of AT&Ts Bell Laboratories, reported that he saw "no reason HDTV should cost any more than a set built with today's technology five to 10 years from now/* However, he conditioned his forecast on con- tinuing progress in the manufacture of low-cost, flat -panel LCD displays suitable for HDTV as replacements for the cathode-ray tube. Another concern is how soon TV stations will begin adding the HDTV high-definition channels that they have been granted, A real possibility exists that HDTV will begin on cable or satellite rather than as direct TV broadcasts- Commenting on esti- mates that it might take five to eight years for HDTV sets to reach 1% penetration of U.S. homes. Stanley Hubbard, head of the forthcoming 50-channel U.S. Satellite Broad- casting Company, noted that no lo- cal station could afford to broadcast to only 1% of its viewing area. How- ever, he said 1% of the vie^A^ing pop- ulation would be a profitable audience for one channel of a satel- lite system covering the entire United States, • iVIore ghost-busting. Shortly after engineering tests by the Na- tional Association of Broadcasters proclaimed that the Philips ghost- canceling system was "superior in every respect" to its four com- petitors. Cable TV Laboratories re- ported on its own tests. It found that the rival system submitted by David Sarnoff Research Center per- formed best "in virtually every test'* The conflict in the findings raised a question about whose tests are better. Was the Philips system better at canceling the widely spaced ghosts typical of broadcast TV, whereas the Samoff system fared better with the closefy spaced ghosts typical of cable TV? The industry eventually expects to select a single system for both broadcast and cable. R-E 48HOUR ELENCO & HITACHI PRODUCTS c.lTS^'ree SHIPPING AT DISCOUNT PRICES ^-.l^'lT^oucon, Htmcni series (Portable Real-^imo DigiTal Storage Oscisbscopes) VC-6023 ' VC-6024 . VC-6025 ' VC'6145- 50MHz, 20MS/S SOMHz, 2aMS/s _ 100MH2,40MS/E_ lOOMHz, 100MS/S ST .695 S2,195 Call Call SPECIAL BUY V-212- 20MHz Scope $409 RSOs Trom Hitachi feature roil motis, averaging, save memoryH Sfnocihjng, inlerpolatiQn, pretriggenng, cureor fneasyferpents. These scopes ena&le moffl accurate, si-cnpfief pb^^rva'jQn af cornplox waveform m B0iiit\on !0 such (und-ions as hardcOpv via a ptottor mterfac^e and wEivflforrr tran&l@r via Ihv RS'232C intefface. Enjoy the comfofl of analog and ihe power lo dig ilal. 25MHz Elenco Osailioscope J $349 M S-1325 :mSSjgmjmM . Dual Trace ^bB^^I^V * Ope ration "^^^^^V , jv Sync • (2) 1x, lOx Probes included Hitachi Portable Scopes DC to 50 MH^, 2-Chcinnel, DC offsetfunc- lion, Atlernole magnifier fynction V-525 - CRT ReacJout, Gu:sor Meas. S995 Delayed Sweep S975 Basrc Model $B7S 40MH2 $775 $695 $625 V-523 V'&22 V-422 V*223 V'222 ■ £OMHz delayed sweep ^ 20MH; deluxe PRICE BREAKTHRU 2QMHZ Otgltol Storage Oscilloscope | • AnaFog/OiglialSoope • 2 K word po r ch an n el mefnofy DS2 0 3 • 1 0M S/S sam p] I r:g rate ^ » Includes probes S-136II 60MHz Delay Sweep $775 HITACHI COMPACT SERIES SCOPES This series pTovicte$ many r»ow lunctiron^ such as CRT Readout Cursor measuremenls {V»10B5/tOe5A/665A),Ffe- Guency Cir. {V-lOBSK Swe*p!ime Autorangung, D«l9y^ swttep and Tnppflr Lock u^ng 4 6-(nch: CRT You Oom tm\ the compactness in Ifirms ol pertofmance aivi ope ration, Dtjal Trace V-665A * 60MHz. DT, w^cursor . Si ,345 V'1060 ^ lOOMHz, Dual Trace Si, 395 V-iaeSA' lODMH^. DLw/cursor $1,649 V-10S5- l OOMHz, QT, w/cursor ^ $1,995 V-1100A- 100MHz. Quad Trace $2,105 V-1150 - 150MHz, Quad Trace $2,695 Elenco 40MHz Dual Trace Good to ^495 S-1340 • High luminanctf 6" CRT • IrnVSensliEvity *10KV Accelefatien Voltage * 9n3 Rise Time * X-V Operation 50MHz • Includes (2) 1x JOx Probes All scopes jfidude probes, scfiematks, operators ^narujal and 3 yeer 12 yrs ^o' Elenco scopes) world wide warranty on parts A labor. Many accessories available tor all Hitachi scopes. Ce3! or wri;e lor oompfeio specff ications on these arrti many other fino osctEloscopes. j 1 Ox Scopo Probes: P' \ 65 MHz Si 7.95 . P-2 1 OOMNz $21.95 DIgilal Capacitance Meter $58.95 3 Ranges Ipf^O.OOOuW .5^ basic accy. Zero coatrol w Case Rig 1 ■ Display Digital Multimeter wllh Irductance & Capacltanu $75.00 LCM-iaso Ten Functions Multl merer with Copacllonce & Tron*lstor Tester fteads Vohs, Ohms Corf&nt, CapaciloiSn Transistors and OicKJes / with caso FLUKE MULTIMETERS Scopemetera WlocTel 93 Model 95 ^Tod61 97 10 Series Model 10 Model 12 (All ModeEs Available CaU) 51,095.00 $1,395.00 51,695.00 $63.95 $79.95 70 Series Mode] 701 1 Mode! 7711 Model 7911 Seflea Model 87 565.00 $145.00 SI 69.00 1289.00 Quod Power Supply XP-580 ■$69.95 12V @ lA ^5V @ .5A F Lilly regu-lated an.d sKort csr:urt protected DIglta] Triple Power Supply $209 r^ fr££lV§lA Futty i^gd^i^t^, Shon. drojit p^cE«^ed Miijfi Z tiini camrct, 2 sQpai ats supplies XP^ia with Analog Holers tl9S AM/FM Transistor Radio Kit with Tialnfng Course Model AM/FM tea $26,95 Mak&s a great schod project Tme RMS41/Z D\q[i MultEmeter M-700T $135 .05% OC Accuracy r1%Re5JS(ance wiiti Ffsq Counler Dale Hold GF -60 1 6 Fu n c t LO n Ge ne roto r vi]ih Freq, Counter $249 Sino. Square. Triongle Pulse. Ramp, .2lo2MHj FreoCeumer V - tOMH: GF-a015wffhout Freq. Meter $179 Function Generator Blox #9600 Prevides sine, Jriangfo. square wavaTrem 1Hile IMH; AM Of FM ca^abiifity Leorn to Build and Progfom Connpufers witti this Kit ■ndudosL All Parts, A^^Qinbly and L^son ji^jinifsl Model MM^eooo Wide Band Signal Generators $129.00 sinning Erom scf^tch you biMid a conipleke s/ste Ojt Mo^Mi&lor ira Ji$r sctadvn you !s wr^te into RAW$, ROIM^ and run i SOflS tmcxtjiXOt^ssDr, which y^os £imi3ar mtichhne langtiag^e) as IBM PC. SG-9QO0 $129 RF Fieq lCK]K4&0MhU AM Modula- licn qI iKHi VartabW o'jiput SG-^500 ytf Digltsl Oi9p!ay & 150 MH£ built- En Counter S249 XK-500 Digital / Analog Trainer A coiTtpIete mfnl-iab far building, tesllng. pTPiatypEng analog and dfgltal circuits Ef&ocO''s DJgltaL'Analcjg Trajn'Sf ts s^sdaily dflilign^>d kt scJiwI pf ejects. witJi S bufit^ln pcwcf E4jppil9S. Inckidfl^ a lunclicin jget ISpfMld ^ 15VACatr Ajtp AMiog - Section ■ Tunciion (j«r«rad6r ^nv. Tri^rtoglUr, S Section P Ellji'ti dAld twtchea ■ Twfl iKj bounc9 l&glc SwIlcbOB ■ qk>tl( Fr9t]Uency 1 to iCOKMl ■ Ck>C^ ^^^.p^itude SVI^P tqu|u« wcvfl $119,95 Kit WE WILL NOT BE UNDERSOLD UPS SHIPPING: 4S STATES S% IL RES 7.5% TAX ($3 min S10 m^i) OTHERS CALL C&S SALES INC. 1245 ROSEWOOD, DEERFIELD, IL 60015 FAX: 709^520*0085 * (708) 541-0710 EE3 15 DAY MONEY BACK GUARANTEE 2 YEAR WARRANTY WRITE FOR FREE CATALOG 11 CIRCLE 109 ON FBEE INFORMATION CAflD LETTERS C E i in MIDI COMPATIBILITY QUESTIONS Judging from reader reaction, my article, "MIDI interface For Your PC (Radio- Electronics, March 1992) has been well-received and has introduced a lot of people to MIDI. But some reservations have been expressed over the interface not being MPU-401 compatible. Maybe some readers have gotten the impression that the interface can be used only with the Voyetra software that was available pack* aged with the card. That is not at all the case. For example, many read- ers have asked if the interface can be used with Cakewalk (another popular sequencer/editor) or Music Printer Plus (a popular program for printing musical scores from MIDI data) or with numerous other pro- grams, and the answer is yes. Some readers may have gotten the idea that since a PCM68 inter- face does not appear on the set-up menu of software that they already own. the software will not support this card. That is usually a case of the PCM68 not existing at the time the software was published, and most publishers will be happy to supply the appropriate drivers for the card if asked. Some packages will listaCMS-101 interface on their menu of options; that selection will generally drive the first port of the Radio-Electroiiics card (the second port doesn*t exist on a CMS-101X Kits presently shipped by PAiA include a disk that has, in addition to shareware toys and tools, VAPI driv- ^ ers for the interface. Many software ^ packages are VAPI compatible, and 3E those drivers allow the user to ex- I ploit both ports of the PCM68 with^ out having to go to the publisher for revisions. By the time this letter ap- pears in print, that disk will also in- clude drivers that run under Windows 3.1. It's true that software packages that can use only an MPU-401 or 12 clone for an interface will not be able to drive the PCM68, Fortunately the number of programs that are so narrow in their scope of support is a small and dwindling part of an other- wise expanding applications base. You can see why: Acomparable sit- uation would be a word processor that worked with only one kind of printer. When you're running a program like Multi-Media extended Harvard Graphics running under Windows 3.1 with your Radio-Electronics interface, are you really so con- cerned that it's not compatible with MPU 401? JOHN SIMONTON ZEROING IN The response to J. Mulfane's question concerning electronic dice rSklp the Zero, "Ask R-E. Radio- EtectronicsH April 1992) drew an avalanche of mail from our on-the- bat! readers. Below is a sampling of some suggestions for improved, easier solutions to Mr Mullane s di- lemma ^ — Editor The problem is the 7490; it s the wrong one. Mr Mullane simply needs to drop in a presettable coun- ter in its place. 1 recommend a 74161 as illustrated in Fig. 1; others are also suitable. Simply enter the lowest or starting number on the preset inputs via grounds and pullup resistors. Then decode the outputs for the highest or ending number with simple gates to trigger the pre- set load pin of the counter The fol- lowing clock pulse simply starts the count over. Although EPROM's might be cheap, this is cheaper. If the reader's skills were at the level where he might have a PROM burner, chances are he wouldn't need to write you. This solution seems more suited to his needs. Furthermore, your assertion that someone "inter- ested in electmnics" should really have a PROM burner on the bench seems inappropriate. My daily work in high-power audio, power control, A e C 0 ENABLE T GLK Q, 0 74161 EWAOLE LOAD 14 13 12 A V3 7410 9 ir} 12 BCD TO 7^SEQMEN1 DE'CODER Va7410 n Fig, 1— One reader's 74161 sorution to "Skip the Zero/' and video display seldom requires the use of ROM's, even though my interest level is high, thank you very much. There 's much more to life than computers, TM. ENZO East Lansing. Ml What is referred to in the fifth paragraph of your response to Mr Mullane as a major engineering problem actualty can be solved with one 7483 4-bit adder Also, the problem of getting the 7490 to reset after a count of six pulses can be solved by using the first three stagesof a 7492. as shown in Fig, 2. The idea is to add one to each cou- nt, which is easy with a 7483: with- out it, we would have a major engineering problem. Thanks for an interesting column. RODGER ROSENBAUM Seattle, WA If Mr Muliane could get by with six LEDs instead of a seven-seg- ment display I suggest he use a 4017 or 4022 counter and connect the Q6 output to the clear input. Whm will it he? Hawiiii? laK Vegas? Mexico? The Ba- hiiniiLs? irs tip to you. We're };()ing lo send you a tree c<)tipoii for up 10 six days and five nighB of free lodg- ing ai ilie desii naiion of your choice. Now^ did we get your at- lention? 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You're going to be very impressed with the book selections as well, lliese are not ail paperbacks, but the same, high-qual- ity volumes you see in bookstores at m;my limes your owti pur- chase price. Frankly, there just isn*t enough room on this page CUGCK Inc. P.O. Box 4099 Rimiingdale, New \brk E!75^^ rrentlemen: I've encloM^tl ,S 19.*)5 \n M\ pavinent, Plra.U' send my 'The Great 1\vo for Ont' Give A^ay" booklei of 40 coypons and caialog. □ QicckliKkacd 13 (dip coupon and mml lodayffki mi sendcmh ihwagb the mail) INPUT A INPUT B 12 to J- 9 3 T 13 JL +5 B1 AI A2 A3 12 A4 33 CO 14 B2 B3 TO 0358 15 Fig. 2— A reader's 7492 and 7483 solu- tion to 'Skip the Zero" that appeared in April's Ask R-E. Then consider QO to be 1 and Ql to be 1, and so on. If he must have a seven-segment indicator, he could use a 74HC283 to increase the counter 7490 output by one, EtICHI TAKARADA Rockford. IL The ROM is the hard way to do it. The zero can be skipped with a 74163 counter When it teachers the end of the count you are inter- ested in. just pre-load a 1. Another way to solve the problem is to use a 4-bit adder between the 7490 and the 9368. 1 think both ways are easi- er than programming an EPROM. TOM LEWIS Ft. Lauderdate, FL A quick trip to my trusty TTL data book revealed that there is a one- chip solution to the problem de- scribed. That chip is the 7483 4-bit adder It is a common, inexpensive chip that s readily available from mait-order suppliers. To use the 7483, take the outputs of the 7490 counter and use them as the A data inputs. Set the B data inputs so that bit 0 is tied high and bits 1-3 are tied low. Also, be sure to tie the CO input tow. The chip will then add 1 to the 7490 count and output the sum. Then use this sum to both drive the 9386 decoder AND to provide the inputs (bits 0-2) to the AND gates used to reset the 7490, When the 7490 reaches the count of 6, the 7483 adder will out- put a 7. creating the needed reset pulse. GEORGE BARBER Fort Worth, TX Your suggestion is overkill. If you carefully read a 7490 's function ta- ble. you*d see that the chip has two R9 inputs. When both of those in- puts are high, the 7490 will be set to 9= The 7490 s QD is not used be- cause the count number that the dice need is from 1 to 6. Thus, set 9 equivalent to 1. Then use a three- input AND gate to decode QB, and QC. The output of the AND gate is sent to two R9"s. That con- nection can guarantee that the counter number is always between 1 and 6. YONGPIHG XIA Torrance, CA As an out-of-work EE* I now have the time to (hink up alternate solu- tions to the ones given in Ask R-E, I guess it's the equi^fent of out-of- Differential Oscilloscope Probe An active probe for making differential measurements with any oscilloscope • Safe - make floating measure- ments with oscilloscope grounded • Easy to use - small, light, with internal battery • Simple - needs no isolation amplifier • 15 MHz bandwidth • For power supplies, large motor drives and similar applications Model ADF15' $375 PROBES. INC. TPI 9176 Brown Deer Road • San Dfego. CA 92121 TEL: (619) 552-2090 • FAX: (619) 535-1260 Toll Free 1-800-368-5719 PLUGriiUTO THE WEATHER! Ihe IK'S- JO Windsutlon roof-top sensor plugs dlrcilly into the PC Gajne Pon. It sends you immediate measurements of your local weather paiterns. Wind speed, direction and gust \i\ue data are continuoiish dispLi)¥d, Outride temperature. 24 hourextrttijesind ui n d chlU tallies are opt jonal . Mont hi of infortnaticiii can be stored for viewing. plotUng and ajiiiy'sts. To plug into the wt^aihtr. calj the order line: 1 800 -992 ■ 8110 ^WeatherPort l2054\e%tdiQtyfl*v Fax 27^-6429 ORClf T23 ON FREE WFOfUiJaiON CARD dflCLE I&3 ON FREE IHF0RMAT10H CARD work writers doing crossword puzzles. I came up with two after- native solutions for Mr. Mullanes dilemma. The cheapest would be to use a 90-cent 74190 chip instead of the 7490 CFig. 3X That would allow a 1 to be loaded at the instant a 7 is reached. The 7 would never show for any appreciable amount of time — only long enough to cause * 2 3 4_ 1 5 ' L 7 8 n Rg* 3 — A reader's 74192 substitution so- lution to "Skip the Zero" that appeared in Aprii^s Ask the 1 to load, (A 30-cent. 3-input NAND would also be required.) Another solution is a little more expensive than yours, but I feet that it would be the most elegant solu- tion that could be accomplished with a single chip (not including clockX !*m of the opinion that this problem is screaming for a PAL so* lution. I thing that, unless a hobbyist were seriously into micro- processor/controflers. that a PAL prctgrammer would be a better in- vestment (albeit more expensive) than an EPROM programmer I love Radio-Electronics — it's both informational and educational, and I save each issue for reference. THOMAS HOLLOWAY Miami. FL A DOG-GONE GOOD ARTICLE The article "Remote Conlral for your Dog" (Radio^Electronics. April 1992) caught my attention. I am anxious to build that unit as I, too. am one of the unfortunate few who have a semi-uncontnollable ca- Continued on page 73 4 »:iiiga'f«Tvrni no input? 1$ time Ixtse drift specified per year, or just per monlh? From 0' to 50' C, or only at naom temperoture? 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Use The Free Information Card for fast response. z 8 in 30 THE MODERN AMPLIFIER CIRCUIT ENCYCLOPEDIA; by Rudolf R GraL TAB Books, Division of McGraw-Hill Inc., Blue Ridge Summit, PA 17294-0850; Phone: 1-000-822-8138; $12.95. Written by an author well-known to readers of Radio-Electronics, this encyclopedia is intended to shorten your search through the hundreds of pages of larger circuit en- cyclopedias to find a spe- cific circuit. It provides fast, easy access to more than 250 ready-to-use amplifier circuits. Those range from audio, video, and radio-fre- quency amplifiers to opera- tional, instrumentation, and voltage-controlled ampli- AMPUFIEfJ CIRCUIT CIRCLE 36 ON FREE INFORMATION CARD fiers. The circuits in Grafs encyclopedia are orga- nized by application for easy reference. Monsover. they are presented in the the same format m which they were originally pub- lished to prevent transcrip- tion errors. Each schematic is accompanied by a brief circuit explanation. A sec- tion at the back of the ency- clopedia lists the publica- tions in which each of the circuits was originally pub- lished, making it easy for the reader to obtain sup- ptemental information. TTL POCKET GUIDE; VOL UMES I, II, AND III. Elec- tronics Technology Today inc., RO. Box 240, Mas- sapequa Park, NY 11762-0240; $18.95 plus $3.50 shipping and han- dling for each book, or $50.85 plus $8.00 shipping and handling for the three- volume set. CIRCLE 37 ON FREE INFORMATION CARD This three-volume set of pocket-sized books pro- vides a compnehensive list- ing of commonly used transistor-transistor logic CTTL) products from all ma- jor manufacturers. All cur- rent families are covered, including standard, low- power, advanced, ad- vanced low-power, and fast Schottky. Each page is lim- ited to the coverage of one device, and it is divided into eight sections. The first gives the device's sche- matic v/ith a clear, simple logic diagram. The second contains a brief circuit de- scription as a quick over- view of the device s internal structure. The next section gives details on operating the integrated circuit, de- scribing fnput signals or levels at individual pins. The fourth section lists pri* mary applications, and it is followed by a summary of essential data. The next section includes a table fisting the devices available in each TTL family Finally device description and type- number references are highlighted for easy ref- erence. An index at the end of each book lists the man- ufacturers of each device. RTTY DATACARD; from liare Publications, RO. Box 493, Lake Geneva, Wl 53147; Phone: 414-248-4845; S6.00 plus 50 cents shipping and han- dling* CIRCLE 38 ON FREE INFORMATION CARD Converting radiotele- type tones into readable material can be a big hurdle for persons monitoring RTTY. even when they are using the latest decoding units. Thi^ two-sided. SY2 X 11 -inch, thickly laminated datacard simplifies that process. It presents and explains the Yarbrough Ma- trix RTTY Tuning Method, developed by Chuck Yar- brough, a seasoned RTTY hobbyist who happens to be a columnist for the Speedx Shortwave Club. One side of the card ex- plains RTTY emission modes and the Yarbrough system, while the other side contains the Matrix Tuning Table. A list of baud rate and various RTTY transmission methods classed under narrow, me- dium, and wide shifts for that tuning rate is in the ta- ble. It also summarizes the tuning method. 1992 CATALOG; from Parts Express International Inc., 340 East First Street. Dayton, OH 45402; Phone: 1^800-338-0531; free. This 148-page catalog is filled with descriptions of electronic parts and ac- cessories: it is geai^d to- ward consumer electronics and the technical hobbyist- The catalog includes exten- sive lines of electronic components such as speakers and audio ac- cessories for home and car Also covered are repair parts and accessories for CIRCLE 39 ON FREE INFORMATION CARD CATV and VCRs. semi- conductors, tools, and telephone-related prod- ucts. Under supplies are chemical solvents, wire, and connectors. The cata- log even includes books and videotapes on elec- tronics-related subjects, and parts for arcade- games. The illustrated cat- alog contains product de- scriptions, prices, how-to- order information, and a comprehensive index. R-E GET THE LATEST ADVANCES IN ELECTRONICS WITH A SUBSCRIPTION TO HinaaiD SHOPPER SWEEP BJKCniOH FHEQtlEMCTCOUUm^ cAEUm ^OiW Find out hmr ti worlo^ BUOI] A Wmxm EXERCISER TUflM ARY PHQHE Itnn AKiGlt-OUiUJTY SP£AK£HPKVNE AHALO&TD-DHSfTftL CONVifiSHlIt Ihi IBM PC ENXV THE WORLD OF ELECTRONICS EPCH MONTH! Now you can subscribe to the best elec- tronics nnagozlne. The only one that brings you articles on — electronics projects, tech- nology circuit design, communications, new products and much more. Radio-Electronics looks to the future and shows you what new video, audio and com- puter products are on the horizon. Whafs more you'll find helpful, monthly deport- ments such as Video News. Equipment Reports, Hardware Hacker Audio Update, Drawing Board, Communications Comer, Ail designed to give you instruction, tips, and fun. Radlo-Electronlcs gives you exciting articles like: • ISDN: The Telephone Network of Tomorrow • The Facts on FAX • A Digital Phone Lock • How To Design Switching Circuits • EfA-232 A real standard for serial interfacing? • Build a synergy card for your PC • '386 Power at a "286 price • Build a biofeedback monitor • More on Multiplexing FOR FASTER SERVICE CAU TODAY 1-800-999-7139 DON'T DELAY SUBSCRIBE TODAY! Just fill out the order card in this magazine and mail it in today. Welcome to. . . SCIENCE The y^mateur Scientist's Journal Embark on an irresistible new journey into the realm of mystery, challenge, and exploration! The perfect magazine for the budding scientist, the serious ^ amateur, the professional who would like to relax, J^**"^ and those who simply want to gaze at the stars. Science PROBE! — the only magazine devoted entirely to Amateur Scientists! If you are fascinated by sci- ence in all its many forms . . 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Name , Address. -State. City . All Orders payable in U-S^A, F^nds only. -ZIP. ON SALE AT QUALITY NEWSSTANDS, CONVENIENCE STORES AND SUPERMARKETS GET YOUR COPY TODAY— S3.50-U.S.A.— S3.95-Canada BUILD THIS FM STEREO BROADCASTER You'll Und countless uses for this versatile FM stereo tfsmmltterJ LUTHER M. STROUD. CET N5TVY COMr*ACT DISCS. OR CD'S. ARI-: QUITE POPUIJVH THl on the go, too. Personal portable CD players convenient size— but their disadvantage is 1 phones can enjoy the music. Howeven it you ten youll be able to listen to the CD audio on ai Ihc can at the beach, or in the yard. Since the any line-level audio source, other application wireless microphone— are possible as well The low-power, low-cost FM-stereo trans ml signal of only a few miGrowatts, But thats t quality stereo signal to any FM i-ecelver u uses an integrated circuit specifieally des; transmitter. Very few support component! ;nE DAYS, NOI^ ONl.Y AT HOMK HUT are popular because of their hat only someone with head- l)uild our stereo FM transmit - receiver — whether its in llRismitter can be used wiih s~sueh as a baby mGnttor or at well build develops a wer to transmit a high- I 50 feet. The project a complete FM stereo ed. FM basics Many simple wireless FM transmitters are monophonic only. A stereo broadcast signal has two channels: left and right. The audio signals occupy a bandwidth of 50 to 15,000 Hertz, with the higher frequen- cies given a treble boost or pre- emphasis for noise- reduction. Both channels are added lo- gether and broadcast as main channel audio (L + R) so that monophonic FM receivers will be able to reproduce all of the program material for the lis- tener to enjoy. Along with the main channel audio, a stereo signal contains a 19-kHz pilot carrier at 10% am- plitude of the main channel, and a sideband subcarrier from 23 kHz to 53 kHz containing the difference between the right and left audio signals (L-R). The stereo receiver uses the 19- kHz signal to recreate a phase- locked 38-kHz signal (sup- pressed at the transmitter) to decode the sideband carriers back into the right and left channels. Figure 1 shows the frequency spectrum of an FM- stereo signal. The receiver also provides a treble cut (called de- emphasis), which compensates for the pre-emphasis that was added at the transmitter How it works At the heart of this project is ICl, a BA1404 FM stereo trans- mitter (see Fig, 2}. The left- channel input signal is adjusted to proper level by Rl. Ti"eblc boost (pre-emphasls) Is pro- vided by the parallel combina- tion of CI and R3. That tailors the audio response to the 75- microsecond standard set down by the FCC. Audio is coupled by CIO into the left-channel input of ICl at pin L Stray RF signals are bypassed to ground by C2 to prevent unwanted feedback. The right-channel input cir- cuitry to pin 18 of ICl is identi- cal to that of the left channel. Power-supply decoupling is done by C14. and any previous amplification to the audio input is decoupled by CI 2 on pin 2 of the chip. A 38-kHz signal is needed to multiplex the incoming audio and create the pilot carrier. The internal circuitry of ICl sup- ports the use of a 38-kHz SX cut crystal, as shox^-n by the dashed line in the schematic of Fig. 2, However, the 38-kH^ crystals aredifficull to find, and they can be costly when you do, A more readily available crystal* man- ufactured by Statek, operates at 38.400 kHz. It will work in most situations: tests made during the development of this project showed that some FM stereo re- ceivers wouldn t lock reliably to the pilot carrier derived from 38.400 kHz crystal. The solu- tion was to use a highly stable external Hartley oscillator made from low-cost, easily obtainable parts instead of either crystal oscillator. The SS-kHz sine wave is gen- erated by Ql and the surround- ing components (the Hartley oscillator). High-gain transistor Ql has a beta of over 300; lovver- gain devices might not work due to the low supply voltage (1.5 volts DC) that is provided by a single AA cell. The adjustable coil used for Tl is a first inter- mediate-frequency (IF) trans- former found in portable tran- sistor radios » and it*s designed for 455-kHz operation. The coll in Tl is loaded with enough ca- pacitance by C23 to bring its operating frequency down to PILOT 19fcHi SOBCARRtEB 33k Hi STEREO-OlFFERfNCE AUOlO (L-a) 3BkKz A 53kHi FIG. 1— THE FM-STEREO FREQUENCY SPECTRUM contains left and righl channels broadcast as main channel audio (L f R), a 19'kHz pilot carrier, and a sideband subcar- rier from ZZ to 53 kHz containing L R» about 38 kHz, You can adjust Tl's core to put the oscillator ex- actly on frequency, Altliougti the oscillator might drift more than a quartz crystal, its not a problem because receivers use phase-locked loops that can track the minor drifting. Note that the circuit wont oscillate if transformer TTs wiring is re- versed. A bottom view of Tl is included in Fig. 2 to help you with the wiring. The multiplexed audio exits pin 14 of ICl and is mixed with the pilot carrier on pin 13 using the network ofRS. R6, C22, and C13. The resulting signal is ap- plied to the modulator input at pin 12. 'lb prevent any RF feed- back problems, pin 12 is by- passed by C6. A Colpltts oscillaton operating from 88 to 95 MHz, is formed at pins 9 and 10 with (he network of C15 to CI 7, C20, and L3. The coarse frequency adjustment is made by varying the coil spacing of L3, and the fine adjustment is made with C20. RF energ>^ that is generated from the tank cir- cuit is prevented from getting back into the power supply cir- cuitry with bypass-capacitor C7 and RF-choke L2. The modulated signal at pin 10 of ICl is coupled internally to the RF output amplifier consist- ing of CIS. C19, and L4 con- nected to pin 7. That circuit boosts the oscillator signal to drive the antenna, and it pre- vents changes in antenna load- ing from shifting the oscillator frequency. The antenna is tapped at a point on lA for the best power transfer. The design of ICl is optimized for LS-volt operation with an absolute maximum of 3,5 volts. Early testing of this project showed that the transmit range didn't increase significantly when 3 volts was used to power the cir- cuit, and the current drain trl* pled. Therefore, the increase in operating voltage is not recom- mended. The FM transmitter circuit draws only about 5 mA, so a single AA cell should last a very long time. Construction Any circuitry that operates at high frequencies needs proper • 4 1 • 2* • 5 3« BOnOW VIEW .0039 J1 LEFT INPUT C9 .m T ^ - ' ± 17 16 hi J2 HIGKT JNPUT 390K Re 1.5K I mnr — + CI 4 22^T SEE TEXT ( I XTAL1 I 38t(Hz X C24 lOpF t J 1^ 15 MPX MFX BAL BAL AF6H0 OS? PILOT AF01AS B»AS OUT XTAL XIAl --nmjF ipH cie 43pF IC1 BA1ID4 RF MPX MOD OtJT IM OSC OSC C12 .+ CS .001 .001 13 ^ R5 ' 15DK , C22 '220pF C13 JJ" 22iiF ' 14 R6 2,7K 12 RG. 2-'THE HEART OF THE FM TRANSMITTER Is a BA1404 FM stereo transmitter IC, Tbd 1«ft input-signal level is adjusted via R1, pre^mphasis is provided by C\ and R3, and audio is coupled by CIO into the left-channel input The right*channel input drcyhry is identical grounding and shielding. How- even to keep this project as sim- ple as possible, a PC board was not used. Instead, a single- sided copper-clad blank was used, with the copper on the component side forming a ground plane, and poinl-to- point wiring done on the under- side. You should be able to lo- cate all of the necessary parts for this project. If you can*t find some of them, they are available from the source mentioned in the Parts List. To prepare the blank, drill four mounting holes in the cor- ners of the board- the author used the mounting holes of the aluminum project case as a dril- ling guide for the copper blank. After you drill the four mount- ing holes, put a short screw in each hole secured with a nut. That will form a miniature **ta- ble/' making it easy to drill the holes in the board for compo- nent mounting. Next drill the 18 holes for ICl near the center of the board — a scrap of perforated con- struction board makes a good drilling guide. After drilling the holes for ICl, use a MG~inch drill bit, twislingit between your fin- gers, to remove a small burr of copper around each hole except at pins 3 and 8, which must be soldered directly to the copper That will prevent shorting any of the pins to the ground plane while still providing the circuit with near-perfect shielding. As shown in Fig. 2, many of the parts have one lead going directly to ground. For parts like that, drill a hole through the board only for the ungrounded lead. The other lead can be sol- dered directly to the ground plane on top of the board. It is suggested that you drill and sol- der only a few components at a time. That way Its easier to lay out all the parts neatly Try to keep all leads as short as possi- ble. Also, it's important that de- coupling capacitors be placed as close as possible to the pins of ICl, L3, and L4, You can make coil L3 by close- winding three turns of #20 9 C16 15pF -w -Lci Old 2-20pF- C8 .001 -4t 1 ANTENNA C16 ISpF 43pF ' C7 .001 L3 C17 C20 2-20pF 12 ImH enameled wire on the shank of your Vm-inch drill bit and spreading it out to V4 Inch after removal. To make coil L4, close- wind four turns of #20 wire as before, and spread them out to y** inch after removal. Both coils are mounted on the board Vis Inch above the copper surface. Place the coils at right angles to each other and at least one inch apart to reduce coupling be- tween them. The RF chokes (LI and L2) should also be mounted at right angles to coils L3 and L4. Checkout and time up Take a few minutes to review your work. Make sure the cop* per is removed from around all holes Intended for component lead pass-through. Before ap- plying power, make a few checks with an ohm meter from ICTs pins to ground to see if any shorts exist where they shouldn't be. Also check for proper polarity of the elec- trolytic capacitors. Connect the battery and measure the cur- rent drain; it should be under 5 milliamps. Attach the antenna to the top of L4. at the first turn from the end that is connected to pin 7 of ICl. The 17 inch an- tenna on the prototype Is the length most often found on por- table radios: use only enough length of the antenna to avoid interfering with other nearby radios. Connect a stereo audio signal to the transmitter— left at Jl and right at J2. lime your FM receiver through the band lis- tening for the transmitted sig- nal Set C19 and C20 at their midpoints and adjust L3 for about 92 MHz. You can now use C20 to fine tune the desired fre- quency. Although you probably have a good transmitting dis- tance already, you can tune the circuit for maximum output by watching the signal-strength indicator on the FM receiver you're using, and adjusting the coll spacing of L4 with a plastic tool. As you get close to max- imum, the coils are slightly in- teractive, so adjusting one will affect the other Repeat the pro- cedure until you reach a max- imum output. With a stereo signal applied to Jl and J2, lis- ten to the output from the FM receiver, preferably through headphones, and adjust Rl and R2 to the point Just below where distortion occurs on loud portions of music. An input level to ICl just below 200 mV is recommended. FtG, 3— A SINGLE-SIDEO copper-clact blank provides a ground plane on the component side, and po1nHo>point wir- ing is used on the underside. PAFTTS LIST All rasistors are Va watt. 5%. un- less othenMise noted. F(^R2— 20,000 ohiTs, potenlioine- ter R3, R4— 75.000 ohms R5— 150.000 ohms R6— 2700 ohms R7— 390,000 ohms R8— 1500 ohms Capacitors 0.001 |iF, ceramic disc C10^C14— 22 iJiR 16 voits, elec- trolytic CI 5, CI 6— 15 pF, ceramic disc, NPO C17, CI 8 — 43 or 47 pF, ceramic disc, NPO C19. C20— 2-20 pR trimmer ca- pacitor C21, 022—220 pR ceramic disc C23— 0.0039 p-R Mylar, 5% C24— 10 pR ceramic, NPO (op- tional, see text) Semiconductors 101— BA1404 stereo FM transmitter Q1---2N5210 NPN transistor Other components XTAL1— 38-kH2 crystal HC-18 style (preferred) or 3S.4-kHz crystal (both optional, see text) St— SPST toggle switch T1— 455-kHz 1st IF transformer (Sumida 1202-0042, Mitsumi 41 OB, or equivalent) LI, L2— 1.0 microhenry RF choke Ua— three turns of #20 enameled wire wound on ^e-inch fomi — four turns of #20 enameled wire wound on ^sMnch form (tap at one turn) Jl, J2— RCA phono jack J3— feanana plug and jack for an- tenna Miscellaneous: 17-inch telescop- ing antenna, single- sided copper- plated PO*board blank, 8 inches of 20^auge enameled wife, drill l^s, suitable metal enclosum, AA battery holder, wire, solden hard- ware, etc. Note: The following items are available from Pershing Tech- nical, RO. Box 1951, Fort Worth, Texas 7610M951: • A kit of all board-mounted components, coil wire, 3x5- inch undrflled PCB blank, AA battery holder, and audio con- nectors (crystal Is not in- cluded)— SI 9 50 Price includes first class ship- ping costs. Orders outside USA add $2. Please allow from 4 to 6 weeks for dellvety. Fia 4— A WIRELESS MICROPHONE can be made by adding an electret eon- denser microphone to the J1 input* The 38-kHz oscillator is best adjusted with a frequency coun- ter connected to pin 5 of ICL If no counter is available, adjust the core of Tl noting the posi- tions where the receivers ster- eo-indJcalor light goes on and ofT. Adjust the core midway be- tween those two points. Figure 3 shows the prototype stereo transmittcc Further refinements There might be times when yoia wish to transmit a mono- phonic signal, such as a speak- ers voice to an auditorium sound system. A switch can be added to the circuit to place a 0.01-}jlF capacitor from ptn 6 of ICl to ground to Inhibit stereo operation. If permanent mono- phonic operation is desired, the 38-kHz oscillator components and C5 can be omitted from the circuit. Adding an elect ret condenser microphone to the Jl input with a 2200-ohm resistor con- nected to + L5 volts will convert this project to a wireless micro- phone for baby- room monitor- ing or lecture-hall use. Wire the parts into the circuit in place of Rl as sho^Ti in Fig. 4. Stereo operation allows you to double upon the inputs. You might try adding vocaJs on one channel and an instrument on the other for broadcast through your ster- eo system. You could also monitor the telephone or baby on the left channel and listen to your scanner on the right chan- nel — all while you wash your car or mow your lawn» while wear- ing a Walkman-type receiver Those are just a few of the many possible uses for this simple project. We Ye sure you can come up many others. If you do* let us know what they are* R-E To Get The Current Rate, You Have To Push The Ri^t Buttons. Announcing the new toll-free number for U.S. Savings Bonds, Now, if you want to find out how much interest your investment is earning, simply call 1 800 4 US BOND, The rates are adjusted every six months to keep pace with the market, and there is a guaranteed minimum yield when held for five years or more. So push the right buttons — 1 800 4 US BOND — and find out how much your U.S, Savings Bonds are earning today* STANLEY LEfNWOLL RF Spectrum Prepped for Next Century REI'RESENTATIVES OF COUNTRIES with a stake in tdecommunlca- tions me I recently In Tor- rcmolinos, Spain, to reallocate parts of the radio-frequency spectrum for satellite and space commun teat ions services in the 21st centun,*: But the meeting had its share of contention as nationa] delegations clashed over frequency redistribution. The World Administrative Ra- dio Conference (WARC-92K held from February 3 through Marcli 3, allocated frequencies for many different concepts related to satellite and spacecraft to Earth communications. Some proposed terns thai require special frequencies are only vague concepts, but others could be started even before the turn-of-the-century. Consider these possibilities: • A cordless telephone system that will permit you to dial an- other phone anywhere on earth using a consteUatton of 77 low- orbiting satellites. This system would also permit you to phone, page, or send fax messages from airplanes, ships at sea, or mov- ing cars. • A sa tell lie system thai cli- rectly broadcasts strong, clean non-fading radio signals to home receivers worldwide with compact-disc qusUity reception* • A satellite television system that beams clean sharp images directly to your home that are better than those received di- rectly from terrestrial trans- mitters or cable, WARC-92 also allocated Earth and space exploration frequen- cies* including those required to establish a lunar colony and for a manned expedition to Mars. In addition, WARC-92 al- located an additional 790 kHz of RF spectrum to high-frequency broadcasting (HFBC). and adopted a resolution calling for a future conference lo plan HFBC. Nationalistic squabbles beset the conference that allocated frequencies for 21st'Century telecommunications Ibugh aUocation decisions Altliough many of WARC-92's accomphshmenls read like a chapter from Star Trek, they did not come easily. Participants found that attendance was strenuous, some delegations were highly contentious, and the results of certain sessions were confusing. WARC-92 reallocated fre- quencies in different parts of the electromagnetic spectrum rauj^hif; from hii^li IVt-quency (HF— 3 lo 300 MHz) ail the way up lo the extra-higii frequency (EHF— above 150 GHz]. Conference accomplishmeEts WARC'92s acconipiishments Include: 1, High-frequency (HF) alloca- tions. Figure 1 shows the addi- tional frequency allocations made for high-frequency broad- casting. Four conditions were imposed on those allocations: • They were limited to single- sideband (SSB) only. • Their use is subject to plan- ning procedures of future VVARCs. • They were allocated to the fixed and where appropriate, the mobile services until April I, 2007. • Existing fixed and. where ap- propriate, mobile services can continue on a low-powen na- tional, and non-interference basis taking into account exist- ing [ll^'-broadcasttng schedules. A future plan n J tig WARC will probably be scheduled for 1995 or 1996. In preparing for this important radio conference, the United States Delegation pro- posed the expansion of the shortwave broadcasting bands by an additional 1125 kHz in Europe. Africa, and Asia, and 1325 kHz in the Americas. But a large bloc of developing coun- tries from Latin America, sub- Saharan Africa » and Asia stead- fastly refused to reallocate that amount of the RF spectrum to broadcasting. The bloc pointed out that the HF bands below 10 MHz are used extensively in their coun- tries for intenial point-to-point communication, and they are extremely congested. Con- sequently, those developing countries were adamant about releasing large amounts of spec- trum below 10 MHz. To avoid the possibility that HF broadcast- ing would not get an/additional spectrum during WARC-92, an tVleventh-hiuii' c oiupromise wys struck, and a total of 2000 kHz was reallocated In the bands be- low 10 MHz. Mindful that the amount of spectrum reallocated to HF broadcasting was insufficient, the United States Delegation de- clared that WARC-92 failed to make adequate provision for that service, particularly below 10 MHz. The delegation an- nounced tliat if "reserves the right to take the necessary steps to meet the HF needs of its [U,S. j broadcasting service." The extension bands will be* come available lo HF broadcast- ing on April L 2007. They will be planned, and can only be used in the SSB mode.EP 2. Salclhte sound broadcasting (BSS): The issues 1 ere pro- duced a genuine tug-of-WARC, The conference was divided from the outset on allocation of frequencies. Most Europeans wanted the more economical and propagat tonally suitable Band, with an allocation around 1.5 GHz. However, the U.S. was firmly opposed to that allocation became militar>^ aero- nautical sendees are now oper- ating in that band. The U.S. wanted the allocation in the S- band, around 2,3 GHz, Other countries, notably, China, Rus- sia, Japan, India, and Pakistan, wanted the BSS allocation to be around 2,5 GHz, (See Fig, 1) In the end. BSS allocations were made In all three bands on a regional basis. In the U.S., sat- ellite sound broadcasting is al- located in the 2.31- to 2.36-GHz band. However, China, Russia, MHz 1 1 1 AIJIK 5.90- 7.30" 9A- 11.60- tZ05- 13.57- 13.80- SM ?.35 9,5 11.65 13.60 13.87 1 1 1 -15.60-17.48- 1B.90- 15.80 !7,55 19.02 HF BAND HiGH-FFlEGUENCY BHOAD€ASTI«G (HF) REST OF WORLD EUROPE USA ASIA \M2' 1.492 40iyiKz CENTERED ON 1.50 2.31 - 2.36 2.655 w- 5€MHz 120 MHz LBAIID SBANO 6Hz 13 14 15 n mwm SOUND ^roadcastihg (bss) WESTEBN HEMlSPHtRE EASTERN HEMISPHERE FEEDER FEEDER 17J- TBI- 214- 24,25- 17,8 18.4 ZZO Z^M 17 \ 11^19 20 03 a.3 BAND 1.6 KBATJO HtGH-DEFlNITlOM TELEVISION (HDTV) FFiEQUENCY ALLOCATIONS IN THREE REGfONS of the BP spectrum. Jiipan. India, Pakistan » and several other Asian coun tries will use the 2. 535- to2.655"GHz band. TYic rest of Llie world will use (he i.452- to band. All of those uses will be limited to digital aiulio broad- casting (DAB). WARCV92 agreed that the upper 25 MHz oi'each band can be used immediate Ly, provided that suitable eoordi- nation procedures are followed. 3. High-definition television (HDTV). This servi<'e ran into problems similar to those en- counlered in BSS, and there was no agreement on worldwide allocations. Instead. Europe, Af- rica, and ^\sia will use the 21.4- to 22-GHz band, and ihe Amer- icas will use the 17.3- to 17. 8- GHz band. Feeder iinks will be in the 18.1- to 18,4^GHz band in the Aniericas> and 24.25- to -25.25-GHz band elsewhere. (See Fig. 1) These bands will be- come available on April L 2007. Prior to that date, HDTV could be implemented, provided that existing ser\4ces arc proUeled, 4. Mobile satellite serviee, and a era nnuticcil pu bile eo t res p on - deuce (AIH::). The servicx^s that most excited WARC^92 atten- dees occur in the frequency bands assigned for telephony, worldwide paging, and fax ser- vices using many continually orbiting rather than geostation- ary satellites. in 1990 Motorola piojjfjscd a global telephone system calkxl Iridium (see box). The APC sys- tem would enable passengers on commercial airlines to make phone calls or send FAX mes- sages anwhere on earth. Fre- quencies for these services were allocated in bands between 300 MHz and 3.0 GHz. and they in- clude allocations for a future public land-mobile tele<:om- muni cat ions ser\^iee (FPLMTS). That service would, among other services, permit anyone in a moving automobile with a car phone to call armvhere on Earth. Altiiough some worldwide ex- clusive alkx'ations were made, the interregional jousting that took place in BSS and HDTV also affected the mobile satellite sen^iee. Once nianyof these sys- tems are implemented, it will be necessary for the systems to car- ry dual standard equipment. For example, an airpiane cross- ing tlj<^ Atlantic must carry equipment that operates in Ihe frequency Inmds allocated for the Western as well those allo- cated for the Eastern hemi- sphere. The worlds elect ronie equipment manufacturers can expect to stay busy for years to come meeting the demand for equipment tliat will operate at the many WARC-92-al located frequencies, CqiJtiniAed on page 73 GLOBAL TELEPHONE NETWORK OF 77 SATELLITES SATEIUTES MOVi; tJORTH TO SOUTH :iaooo MPH EARTH ROTATfON-WEST^TO EAST IRIDIUM TELECOMMUNrCATIONS NETWORK would hmve 77 moving satellites !n seven polar orbits at a 500-mile altitude. iridium, a proposed global cellular telephone network, would put 77 relay satellites in earth orbit. Those moving transceivers or "cell sites" would be sup- ported by 20 or more ground stations connected to terrestrtai telephone lines. The system promises worldwide tele- phone, paging and fax service. Unlike existing telecommunications satellites that remain in a fixed position 22,300 mile above the equator, Iridium's satellites would orbit the earth at an al- titude of 500 miles. The 77 satellites would be launched and synchronized in seven polar orbits with ti satellites in each orbit. fvlovtng from north to south at 18.000 mites per hour, the satellttes would be- have like electrons orbiting the nucleus of an atom. The earth will rotate west to east under this ' sheir of satellites. As a result, at least one satellite will be in position above the horizon ready to transmit and receive calls at all times. Moreover, the low- altitude orbits will per- mit half- watt pocket phones to be used. This ambitious scheme, proposed by f^otorola Inc, has received frequency spectrum allocations although it has not yet been authorized by the FCC. In addi- tion to revenues expected from tele- phone, fax, and paging services, Motorola envisions considerable work in making the satellites, ground station equipment, and pocket telephones. Critics, however, say that Iridium will have to play catch-up with existing cel- lular telephone services; and rt will be too expensive to be profitable. R-E THIS MONTH WE CONTrNUE our PC-based test equipment series by completing the firsl of several that are com- patible with the IIOOO interface we built last month. We also went over the Front-End cir- cuitry that must be con- tained in each HOOO peripheral. This Iirst pe- ripheral, the TlOOl, contains a 100-MHz dig- ital frequency counter an event/period meter, and a precision capaci- tance meter accurate from 1 pF to 10.000 \iF. Capacitance measurement The Circuit Control Latch section (CCD is made up of 16 control lines that are individu- ally routed to every block depicted in Fig. L The purpose of the CCL sec- tion is to enable, dis- able, reset, start, and stop the major pro- cesses of the TIOOI. The Capacitor Pulse section, when started by the CCL section, produces a negative-going pulse whose period Is propor- tional to the capacitor under test. The pulse produced in the Capacitor Pulse sec- tion enables and dis- ables the 60-MHz clock. To determine the period of the pulse, the output of the clock is connected to the Cap/ Event section which contains the least-significant eight bits (byte 1) of a 32-bit digital coun- ter, as well as a latch used to read those eight bits. The Coun- ter section provides the remain- ing 24 counter bits (bytes 2,3, and 4) as well as three more 8- bit latches that are used to read the count back into the comput- er Tiie complete sequence is as follows; Control data is sent to the address of the CCL. The Chip-Select (CS) section en- ables the CCL to store the con- trol data. The control data disables the Frequency, Event, PC-BASED TEST BENCH The first 11000 peripheral that we^re going to buiid^ the TlOOlp contains a frequency counter^ an event/period meter, and a capacitance meter. STEVE WOLFE as the capacitance meter In this case, the CCL is programmed to deactivate the Capacitor Pulse section and to ac- tivate the Event-Puise section. The Event Pulse section contains a CCL-con trolled inverter/ buffer. The 60-MHz clock is enabled and dis- abled by a negative-go- ing pulse. The inverter/ buffer ensures that a pulse of any polarity fed into the Event Pulse sec- tion will be negative-go- ing upon reaching the Clock section. That al- lows for measurement of either negative-going or posit i ve -go i ng pulses. As with capaci- tance measurement, the counters are clocked at a 60-MHz rate for the duration of the event pulse, and are then stopped* The counter bytes are read back into the computer and com- bined into a single deci- mal value. The resultant period in seconds is equal to the final count divided by 60 MHz. and Timebase sections, and re- sets the counter and Capacitor Pulse sections. Next, the CCL is sent a byte that causes a one- shot to fire in the Capacitor Pulse section. The resultant pulse enables the clock, which enables the counters. When the pulse has ended, the final coun- ter values are read back into the computer. The four counter bytes are then combined into a single decimal value. The resul- tant value is proportional to the capacitance of the component under test. Event/period measurement Event or period measurement uses most of the same circuitry Frequency measurement For frequency mea- surement, the CCL is first instructed to dis- able the Capacitor Pulse and Event Pulse sec- tions, reset al! the coun- ters, and select one of eight available timebases. which are derived from the 60-MHz clock. Next, a timing period begins, and the output of the Timebase section goes low. That allows the Frequency Input section to be- gin counting the frequency that is being measured. The first byte of the input frequency rip- ple carries into the Counter sec- tion (bytes 2, 3, and 4). When the timebase period ends, the output of the timebase section returns to a high condition, dis- abling the Frequency Input sec- tion. The final count bytes are then read back and are com- bined into a single decimal val- ue. The resultant frequency is 8 c 2 1 42 CAP PULSE I 60-MHz ^ CLOCK lAND TIMEBASE^ EVENT PULSE DATA BUS IHANDSHAKE LINES [ADDRESS LINES Ml DATA BUS CIRCUIT CONTROL LATCH DATA BUS FREQ. INPUT (BYTE NPUT I/* El) |S PERIOD J COUNTER (BYTES Z 3. 4)1 FRONT END RG. 1— T1001 BLOCK DIAGRAM. This peripheral contams alOO-MHz digital frequency counter, an event/ period meter, and a precision capacitance meter. equal to the final count divided by the tlmebase period In sec- onds. Controlling tlie TIOOI The first step in controlling any 1 1000 peripheral is to estab- lish a base address and select the desired peripheral. The first bit of code will be: bas = 768 : out bas + 31.L 768 (hex 300) Is the factoty-pre- set base address of the 11000. Next we have an out tobas + 31. Recall that address bas + 31 Is resented for peripheral selec- tion. The TIOOI has a unit or peripheral address of "1," Con- sequently, if you send an out to has + 31 with a data byte of the TIOOI will be readied for full I/O operation. Take a look at the TIOOI sche- matic in Fig. 2, (Note that the Front End circuitry Is absent — you can find that, and a descrip- tion of it. in the June 1992 Is- sue.) A 74HCT138 3-to-8 line decoder (IC21) produces the read function chip selects with- in the TIOOI- it decodes three binary lines and produces a low on one of eight output lines. The low remains active as long as the handshake lines remain active. The handshake lines that come from the Front End are send, rd, and hkn. The ad- dress information present at pins 1—3 of IC2 1 corresponds to A{>^A2 (A3 AND A4 arc not uscd by the TIOOI). The OEN pulse is high as a re- sult of selecUng the T 1001. Ex- ecuting *'a = inp(bas + 3)" will cause sicND and a2 lines to go low, and ao and ai to go high. After 500 nanoseconds, the read pulse (i^) will go low, ac- tivating 1C21 pin 12 for the du- ration of the RD pulse (1 ^is}. If HKN were low, IC21 would not re- spond to read pulses, ben is low in every peripheral except the one addressed with the bas + 31 function. The +0 through +4 designator on the outputs of IC21 correspond to bas-hO through bas + 4 In the software. tJsing that notation, it Is easy to visualize the softwares effect on the hardware. A byte latched into 1C9 can be retrieved using the following: a - Inptbas + 0):a = lnp(bas + 0) A read to bas -h 0 will cause 1C21 T1001 P Resistors R1— 200.000 ohms, y**WBtt, 1% R2— 5110 ohms, Vi-watl. 1% R3— 2200 ohms, v*-watt. 5% R4— 5600 ohms. V^-watt, 5% Capacitors Cl. C2, C7, C8. CIO. CIS, 07, 034. C41~10 jiF^ 35 voJts, eleclrolytic 03, C5, C6. Ct2-Cl5. CI 8. C20-C30— 0.15 nF, 50 voits, monotythtc 04. C9. 011, C31. C35. 036. C38. C39— not used C32— 105 pF, 100 volts, dipped mica C33, C37, C40— 100 ^f, 25 volts, elec- trolytic Semiconductors iCI— 74LS123D duat one-shoi IC2— 74HCT86D quad 2-input XOR gate 103, IC11— 74HCT32Dquad2' Counter and Event sec- tions. Let's assume that you are going to measure a small capac- itor (less than I |iFl. Now IC23 and 1C24 clear ICl-a, ICl-b, 1C7- a, IC7-b. IC8. IC26, and IC29, and another byte from IC23 and 1C24 releases those chips from their reset modes. You are now ready to start ICl* a l>y transitioning its start line at pin 2; that causes ICUa pin 4 to go low and lC4-b pin 8 then goes high. Flip-flop lC7-a— a 74F74 high-speed fHp-flop set up as a divide-by-tvvo — contains the least-significant bit of the 32-bit counter When IC6-d re- ceives a low on pin 13, IC7-a is disabled; when IC6-d receives a high on pin 13. lC7-a is enabled. Therefore, during the time that lCl*a IS producing a negative pulse, lC7*a is counting at a 60- MHz rate. The rest of the 32-bit counter section is made up of lC7-b. ICS, 1C26, and IC29. Each sec- tion ripple-carries to the next. Once the one-shot pulse has be- gun, 1C25 continually reads back IC6 pin 13 to determine if the pulse has finished. When iC6 pin 13 is found to be low, the one-shot has finished and the contents of the counters are read back from IC9, IC27. IC28, and IC30. The four bytes are re- combined by the software to yield one decimal number pro- portional to the capacitance. One-shot circuits cannot pro- duce pulses that Increase with capacitance in a 1:1, or linear fashion. In fact, the graph can be a cur\^e resembling the natu- ral log of 2. To achieve better than one percent accuracy, ma- trices and determinants are used in the software to overlay a correction curve and thus can- cel any nonlinear charac- teristic. That is achieved by plugging capacitors with known values Into the capacitor checker during a calibration process, allowing the checker to learn what capacitance equals what count. Therefore, the TlOOl capacitance meter is accurate from 1 picofarad to 10,000 microfarads. For op- timal performance, the calibra- tion process sliould be repeated everv^ si.\ to eight months. Measuring an event Period measurement is ac- complished with most of the clr- cuitry used for capacitance Q\ icie^t!\iL 2 iU T FROM PtN 14 7JHCT«4(I CLK CI Q2 03 05 0& 09 Ql 4 <3i no T: tm fflOM ic?i PEN 14 EJATA BUS + 5Vf0l TO 1C23 PIN 1 44 FIG. 2— T1001 SCHEMATIC. A MoB line decoder {[021) produces the read function chip selects within the TIQOI by decoding three binary lines and producing a low on one of eight output lines. •'i mmm — r 121 PIN m fROM o PMt 1- >1 Pins ICT-I 03 04 OS 0^ OP 0^ Qi r 10 30 *0 50 10 ... if— » ait 09 010 01 1 01? 01^ I ipQ ^ ^1= QI o: 0.4 1 o B o 45 measurement. All of the sec- tions iniiially disabled or cleared during the capacitance test are treated the same way here. The event input is secured by Dl and R3 when its not in use. When the anode of Dl is brought low. control is given to the Event Pulse input so that a pulse can be measured. If the pulse to be measured is positive-going, IC2-d is pulled high. If the pulse to be mea- sured is negative-going. IC2-d pin 12 is pulled low. That en- sures that any pulse leaving IC2-d pin 11 will be negative-go- ing. Next, a byte is sent to iC23 and IC24 to release lC5-b, lC7-a, IC7"b, ICS. IC26. and IC29 from their reset modes. A positive-going start pulse, which tells the circuit produc- ing the event to begin, is sent out. The input pulse enters 1C2- d pin 13, and a negative-going pulse leaves iC2-d pin 11 and goes to IC4-b pin 9. and the counters begin counting. Flip- flop IC5-b watches Tor the event pulse to end; when the pulse ends (a rising edge is detected). IC5-b pin 9 goes high, disabling the Event section. That pro- vides noise immunity by pass- ing only the first pulse received. Because the pulse has ended. IC6-d pin 13 goes high, indicate FRONT-END PARTS LIST Resistors R1— 33 ohms, 16-pin DIP resistor R2— 2200 ohms, lO-pin SIP resistor R3— 1000 ohms, 10-pin SIP resistor Capacitors C1-C7— 0.15 \xf, 50 volts, monolythicor polystyrene C6^11, G2Ch€2a— 1500 pF, 63 volts, polystyrene C12-C19— 220 pR 100 volts, ceramtc disc Semiconductors ICi^74LS573D Dctal taich IC2— 74LS688D B-bit magnitude com- parator IC3— 74LS245D octal transceiver IC4— 74LS02D quad 2-input NOR gate ICS. IC6— octal buffer IC7— 74LS0flD quad 2-input AND gate Other components J1— 16"pin male header J2 — ^18- pin male header J3— Right-angle PC-mount male DB25 connector Miscellaneous: 17 shorting blocks (for Jl and J2), solder, etc. ing that it is time to read back the final count. Tlie period can then be determined with the for- mula described earlier Meastiiing a frequency As in the other two processes, a set of initial conditions must be established. First bytes will be sent to 1C23 and 1C24 to dls- able ICl-a. ICl-b. lC2-d, and IC5-b. All counters will be reset as before and IC4-b pin 13 is pulled low to ensure that when IC7 is released from the reset mode it will be free-running. The period section consists of IC3-d. ICIO, ICll-b. IC12. 1C13, 1C14, and IC15. Once released from reset, 1C7 produces a CLOCK pulse which Is applied to IClO-a and ICll-b. That part, ICll-b, is the clock enable/in- hibit gate that supplies IC12 with clock pulses, A 74HCT4040D 12-blt counter. IC12» ripple-carries to another counter. IC13. which ripple-car- ries to the last counter in the period section. 1C14. Eight channels from a 74HCT151D 8-channel multi- plexer, IC15> are connected to eight of the counter outputs. The multiplexer output channel is connected to ICll-b, IC3-d, and pin 6 of IC25. a 74HCT573D octal latch. Pin 6 of IC25 is a read -back line for de- termining when the period has ended. The operation of the Period section is as follows: IC7-a» IClO-a, IC17, and IC18 are all released from reset. IC7-b pro- duces a 15-MHz clock signal that is fed to IClO-a and ICll-b. When the first rising edge reaches the clock input of ICIO- a, pin 6 of IClO-a goes low That releases IC12, IC13. and IC14 from reset. Prior to that event, all the counter, or "Q" outputs were low due to the reset con- dition. At this time, ICll-b has a low on pin 5 and a clock signal on pin 4, That produces a clock signal on IC12 pin 10. Since the counters are no lon- ger in a reset condition, they go into a free-running mode. Even- tually, the multiplexer line cur- rently selected is fed a high condition. The high is fed to ICll'b, lC3-d, and 1025 pin 6. When pin 6 of ICl i-b goes high, it inhibits IC12, 1C13. and 1C14, The output of lC3-d was high before the reset was removed, low after reset and before the counter went high, and high after the counter went high. If lC3-d produces a high, then IC16-C is an inverter and con- sequently IC17-b Is inhibited. If IC3'd is low, then lC16-c is a buffer and lC17-b is enabled. In other words, during the time when the counters are not in reset, but prior to the counter output being fed back to IC3-d, the frequency being measured is allowed to clock 1C17, ICI8, IC26, and IC29, The length of the period is determined by the counter output, or "Q" that is allowed to pass through ICi5. The TlOOl was designed to produce eight different time- bases between 0. 1 and 20 sec- onds. The period of any given timebase can be determined by calculating the amount of time it will take for the target "Q*" to go high at the given clock rate. That method is not as exact as it could be, due to propagation de- lays. The preferred calibration method is obtained by working backwards. You input a rela- tively high, known frequency into the counter input and start a period. Once the count is read ORDERING INFORMATION Note: The following items are avail- able from TSW Eiectronics Corp,^ 2756 N. University Drive, Suite 168, Sunrise, FL 33322 (305) 748-3387; • 11000 kit— $65.00 • 11000 PC board only— S35.00 • ilOOOf assembled and tested— $77.00 • 6-toot interface cable (DB-25-6) — SI 2.95 • T1001 kit (mcludes PC board, all listed parts, project case, and pre- assembled front and rear panels — $149.00 • T1001 PC board oniy— $49.00 • T1001, assembled and tested- $179,00 • T1001 software (included free with T1001 order)— $10.00 • Capacitor kit (unmeasured)— $21.00 ^ Capaoilor kit (measured to within 1%)— $26.00 Add $5.00 S&H to any order. Check or money order only. back, the period in seconds is equal to the count divided by the frequency. In thai way you can determine the exact period, propagation delays included. Once you have mapped out the exact value of aU eight periods, you can save them to disk and reverse the equation so that the frequency is equal to the count divided by Ihe period. Constmction lb build the T 1001 peripheral, a PC board is recommended. You can either buy a PC board from the source mentioned in the Parts List or make your own from the foil patterns weVe pro- vided. Note that the parts for the Front End are contained on the TlOOl board shown with a dark line around them. There is also a separate Parts List for the Front End. Do not confuse the two lists of parts, or where they go on the board. Install parts on the board as shown in Fig, 3, Also, for many of the capacitors, notice that there are three holes on the board, with two of them electrically the same. The holes accommodate capacitors of dif- ferent sizes. Use the pair of holes that best fits the capaci- tors you use. The frequency-input BNC connector ( Jl } must be wired to the board as shown in Fig, 3 with shielded cable. Binding posts J2— J4 are connected to the board with insulated stranded wire. For testing ca- pacitors, '^spring jacks" (J5--J7) allow quick insertion and re- FRONT END 0>IC34 (BOTTOM VIEW1 J3 J2 FIG. 3— PARTS-PLACEMENT DIAGRAM. Note that the Front End section Is contafned on the TT001 board shown with a dark line aroy nd It. There are separate Parts Lists for the sections, so be sure not to confuse them. (The extra holes where capacitors are mounted are for accommodaUng capacitors of different sizes,) moval of test capacitors, as well as easy paralleling of capacitors to achieve any desired value. The spring jacks are simple springs bent in a semicircle, at- tached to the front panel with a screw at both ends, and con- nected to the PC board with Insulated stranded wire. There Is one spring jack for large-value capacitors (J5K one for small- values (J7). and a common one for ground (J6). However, a problem with the spring jacks is that a spring is an Inducton and the measured capacitance would vary depend- ing on how the capacitor Is in- serted into the springs. There- fore, a fine-gauge shunting wire must be "woven" around the back edge of each spring and soldered to the Jumper wire that connects the spring jack to the board. Making spring Jacks can be difficult and tedious for the average do-it-yourselfer There- fore, anyone who purchases a complete kit for the TlOOl will receive a preassembled front panel — Its drilled, silkscreened, and all the jacks* including the three springs, are mounted on it, lb save yourselfa lot of hassle If you're not buying the kit* you can use any kind of capacitor test jacks such as binding posts or alligator clips. Four voltage regulators are used in the TlOOl: IC31-IC34, Three of them (1C31-1C33) are LM340T s In a TO-220 case, and the proper heatslnk should be attached to each of them. The fourth regulator (IC34) Is an LM340K in a TO-3 case. That regulator must be mounted on the back panel of the TlOOl case, also with an appropriate heatslnk. and hardwired to the board. Figure 4 shows the com- pleted TlOOl board. Software Each peripheral. Including the 11000 Itself, has its own soft- ware program to control Its own operation. All of the programs end up in one directory as you add more peripherals. Software for the 11000 and the entire se- ries of peripherals. Including the TIOOL can be downloaded all at once from the RE -BBS RG, 4— COMPLETED T1001, A preassembled front panel Is fncluded with the purchase of a T1001 kit (516-293-2283, 1200/2400, 8NI) as a self-unarchiving zip file called I1000,ZIF Both com- piled ajid uncomplied software is Included- Software is In- cluded free with the purchase of any peripheral from the source mentioned In the Parts List. (Software can also be purchased from that source if you're not buying anything else from them and you have no way of down- loading it from the RE-BBS J Be- fore you can do anything with the 11000 system, the software must be installed in your com- puter. To do that, type "Install" and then hit Enter, and follow the instructions you are given. Operation and calibration Before installing the 11000 card in your computer, the card must be calibrated. To calibrate the 11000, you 11 need a dual- trace oscilloscope capable of measuring a 400-nanosecond pulse, two X 1 probes, and a non-metallic alignment tool. Set both oscilloscope channels to 2 volts/division, the timebase to 0,2 microseconds/division, the trigger slope to negative ( - ). and then set the sync source to channel L Power down your computer. COUPONEKT SIDE of the TlOCn board. TftBLE 2— FREQUENCY SOLDER SIDE of Ihe TlOOt board. install the 1 1000 card, and con- nect the scopes ground lead to the UOOOs metal mounting bracket. Attach the channel- 1 probe to TPll and channel 2 to TPS, Boot your computer and change directories to \TSW. Type "CALUOOO" and press En- ter Press the space bar until the status line indicates "WRIT- ING," Adjust the trigger level of your scope until you are in swc with channel L Adjust R12 until the waveform on channel 2 is centered within the waveform on channel I. Move the chan- nel*! probe from TPS to TP7. Press the space bar until the status line indicates "READ- ING. "Adjust R 13 until the wave- form on channel 2 is centered within the waveform on chan- nel !. Move the channel-2 probe fromTP? toTP9, Adjust Rl 4 un- til the waveform on channel 2 is centered within the waveform on channel 1. Power doun the computer and remove the probes: the 11000 is now fully calibrated. All three functions of the TlOOl peripheral must also be calibrated. When the sj-stem is up and running, the main, or *TSW" menu allows you to choose between the different functions of the peripheral. First choose the frequency- counter option, and youll then be presented with the frequen- cy-counter menu as shown in Table 1; pressing the keys shown on the right side will ex- ecute the functions shown on the left side. TABLE 1— FREQUENCY Rinction Press Units (Hz, etc,) Quit Main menu Direct Trmebase Calibrate U Q M D t I C Connect the counter input to a known reference frequency and make sure that frequency is displayed on the screen. Press "C," and answer "Y" to activate the calibration. After you are asked what frequency (in hertz) you are using for calibration, type it in and press Enter The computer will take care of the rest. The event/period menu is shown in T^ble 2, Again » press- ing "C" activates the calibration mode- You will be asked to enter the number of nanoseconds needed to calibrate the period being displayed. The value you enter will be saved to disk and used in all subsequent read- ings. To remove the calibration offset, press "C" and enter a zero. The capacitance- meter menu is shown in Tkble 3. Pressing Function Press Units (uls etc ) U Quit Q Main menu M Positive P Negative N Handshake toggle H Calibration C TABLE 3— CAPACITANCE Function Press Units (uF, etc) U Quit Q Main menu M Large cap test L Small cap test S Zero Z Direct D eXil zefo or direct X Calibrate C "C" and answering from that menu activates the capaci- tance calibration process. You will then be asked to insert v-ari- ous known-value capacitors and press a ke>: The calibration capacitors required are shown in Table 4- The more precise the values of the calibration capaci- tors, the more precisely cali- brated the TlOOl will be. A package of the capacitor listed In Tkblc 4 is available from the source mentioned in the Parts List. TABLE 4^CAPACrT0RS 5pF .47 ^F 10 pF 1.0 ilF 47 pF 4 J p.P TOOpF 10>tF 470 pF 47 ^F 1,000 100 ^F pF 4,700 470 ^F pF .01 ^iF 1,000 ^F .047 ^F 4,700 jiF ,1 pF 10,000 ^F The IlOOO/TlOOl pair should now be completely calibrated. With that and your computer you're well on your way to hav- ing a versatile computer-con- trolled test bench. r-e i ? 49 WHArS NEWS continued from page 6 parks. Several days before the broadcast, a portable Switched 56 "traveling case" is sent to the ball- parks technician. Somewhat larger than a briefcase, the case contains a modem, a codex, a digital service call-up unit, the power supply, and a power cord. The unit s AC power line and input and output connec- tions are plugged in, and a MCts phone number is dialed. The equipment converts the ana- log voice signal to digital data for transmission to the CBS studios in New York where the broadcast is mixed and commerc iais are added. The finished product is than digitally transmitted Cuplink) to a satellite for retransmission (downlink) to all CBS network and affiliate stations, which convert the digital data back to an analog broadcast signal Be- cause the equipment is full duplex, the Switched 56 also carries two* way communication between New York and the broadcast site, CBS made use of the Switched 56 system at the NCAA Basketball Tournament, the Masters Golf Tour- nament, and for live news coverage of the New Hampshire presidential primary. CBS affiliate. KMOX in St. Louis, will broadcast half of its Car- dinals games with the system. Correcting soil contamination According to Sandia National Laboratories, heavy-metal con- tamination of soil and ground water is a widespread problem for the na- tion. Sandia says the problem is par* ticulariy serious at the Department of Energy's weapons complex. The ^ Albuquerque, NM, laboratories are g} studying electrokinetics as one pos- ^ sible technique for the direct re- ^ moval of such contaminants from I* soil waters. ^ In the eleclrokinetic technique, M electrodes are implanted in the soil, e and a direct current is passed be- S tween the electrodes. This has two ^ effects: First, ions in the soil*water solution begin to migrate toward the oppositely charged electrode — a process called electromigration. 50 Second, and at the same time, soil- water begins to flow toward the cathode — a process called electro- osmosis. The combination of those two effects can cause contaminant ions to move toward one electrode or the other promising in-place removal of contaminants from the soil The contaminants are actually removed by one of sseveral methods, includ- ing electroplating at the electrode. Thje other methods are precipita- tion or co-prscjpitation at the elec- trode* and pumping or ton-exchange of water near the electrode. Both electrokinetics and electo- osmosis have been tried for increas- ing the density and solidifying slur^ ries, and to to extract water from liquefied soils, paper mats, and con- crete. More recently electro-os- mosis has removed heavy metals and soluble organic contaminants from saturated clays in laboratory experiments. Sandia is ncm trying to learn more about electrokinetic remediation and to evaluate the kinds of con- taminants and soil conditions that are appropriate candidates for that remediation. The issues being eval- uated are: the removal of heavy met- als with complex redox chemistry, the effectiveness of the process in partially saturated soils, the effects of mixed soils on the process, and methods for scaling the process up to practical field applications. FCC allocates radio* spectrum space for interactive TV The Federal Communications Commission on January 16 voted unanimously to allocate a portion of the radio spectrum for interactive video and data services CIVDS) use, paving the way for a new wireless broadcast industry in interactive television, which will allow consum- ers to shop, bank, and pay bills di- rectly through their television sets, without requiring a telephone line or computer The action was a result of a petition filed in 1 987 by TV Answer CRadio-Electrontcs. February 1992). The FCC, which will allocate one megahertz in the 218-219-MH2 band for use by companies provid- ing IVDS sendees, is expected to issue the first IVDS licenses by the end of this year. Updated area-code plan Since area codes were first intro- duced in 1947, they've had "0" or "1** as the middle digit, indicating to the switch that a long-distance call is being made. With only two of the original 144 codes still avatlabie. we're in imminent danger of "run- ning out" of area codes in the near future. A plan mapped out by Bell- cores North American Numbering Plan CNANP) Administration (Livingston. NJ) describes how new area codes can be distributed; The proposed two-part strategy is de- signed to meet telecommunications numbering needs at least through the first quarter of the 21st century by allowing the numbers "2" through "9" to be used as the mid- dle digit, The plan is the backbone of the NANP Administration s long*range "Proposal on the Future of Number- ing in Worid Zone t," which has been distributed to more than 3000 telephone companies, manufac- turers, governments, and other in- terested parties in the Worid Zone 1 — the United States, Canada, and 16 Caribbean countries — where Country Code 1 is the international- dialing designation. Under the plan. 300 new area codes will be assign- ed to specific geographic areas, tripling the number now available. Ninety more codes will be reserved for non-geographic uses; 80 for per- sonal communications and 10 for special-purpose service access codes such as today's 800 or 900 codes. The remaining codes will be allocated for future growth and as- yet'unidentified future needs. The plan predicts that eventually all calls made in Worid Zone t will require ten digits. Bellcore's NANP Administration, a small group that has the respon- sibility for administering the scarce telecommunications numbering re- sources for all countries in World Zone 1, works closely with local telephone companies that manage local telephone- Exchanges. After hearing industry comments, the NANP Administration will reissue the proposal by the end of the year. Once consensus has been reached, further study of the steps needed to achieve the plan's long-term goals will begin. R V6 > Y5> dG2A Y4 1> k: G2B V3 E> Yl YO 1 JOT m m 26 24 A19 B03 IIS 74iS24$ A8 B8 A7 B7 A6 B& AS B5 A4 Q4 A3 B3 A2 82 A1 B1 m EN T yi9 27 22 JG2'h AO Al A2 A3 A4 AS AB A? A8 A9 A10 Alt At2 A13 WE OE IC4 43250 CS DO D\ m m D4 D5 D6 D7 A14 T 51 -a SI'h 51 20 12 13 15 16 19 12 11- 105 !4 104 15 16 JDi. ID2_ 17 J2L IDO RG, 1— THE COMPLETE SCHEMATIC reveals a simple circuit Gates IC1UTILNAME HEXADOR where UTILNAME is the name of the utility, and HEXADDR is the hexadecimal segment address at which the board is Installed (C800, CCOO, . . . ECOO). Note that although the decoding cir- cuit supports addresses start- ing at GOOD, to avoid potential conflicts the software only al- lows starting addresses of C800 and higher The utilities all work in a sim- ilar manner iypically> a pro- gram first verifies that the user has entered a valid address on the command line. If not, the program terminates; otherwisCt it reads some data from the key- board or a disk file one byte at a time, then writes that data to the appropriate area on the board using normal C pointer arithmetic. The first two utilities allow you to enable and disable the board. DISABLE.EXE works by COMPONENT SIDE shown half size. , iHiiiifiiiiiiiiiiiiiiiiiiinii I r -1 J- INCHES ^ SOLDER SIDE shown hsif size. overwriting the first byte of the ROM with OOh, which prevents the BIOS from recognizing the remainder of the ROM. Con- versely, ENABLE.EXE works by restoring the first byte of the ROM to 55h, SETPASWD.EXE allows you to set the password that must be entered when booting your PC, The password can have a maximum of 15 characters. After obtaining a new password from the user, the program writes it to the SRAM, then cal- culates and installs a new checlcsum INSTROM^EXE enables you to install the contents of a disk file in the SRAM board. Syntax for the command is: C>1NSTR0M FILEfaAMETYP HEXADDR where FILENAME, TYP repre- sents a file and HEXADDR again represents the installa- tion address, Of course you can't install just any file; it must conform to the format outlined above. List- ing 1 shows how the password protection software works. Note first that the software is ORGed to byte 03h of the program. At location 03h, the program calls the main routine. Following that call is a far return, coded as a define byte (CBh). Following the far return comes the pass- word, then a byte (COUNT) that specifies the number of tries the input routine will accept. Then comes the main rou- tine. First, it sets up the key- board, then it checks whether the first byte of the password equals OOh, If so, the routine simply terminates; otherwise it continues by displaying a sign- on message. It then goes into a loop that collects a CR-termi- nated password from the user, and checks it against the stored password. If the user does not enter the correct value within three tries, the program dis- ables the keyboard and goes into an endless loop, forcing the user to reboot. Construction and use We recommend using a PC board for this project. Use sock- ets for all IC s. You might want to use one for the SmartSocket (IC4) but doing so increases overall board height so it could LISTING 1— ASSEMBLY SOURCE PAOE ,133 I a IBM PC PRINTER COWDEWSED MODE SKJKENT PARA FUBLIC *COOI' A83UHB CSxCSea;t}SiC3EX;.3StCS^HESECSEG SET BY DOS LOADER IWCLUDE org tih J BIOS ROM SIGNAWRE DISPU^YI.KAC TOP: NEWWORD call zuln EB OCBh DB DM ' avento' , ODtin ' 16 W?i7i 3 MOV AL.OOh OUT 21H MOV DShCX MOV BYTE PTB DSi count, 03h MOV ALhBYTE PTR CS: password CMP AL^OOh JE OKOUT JJSP OVERIT password I 6»t keyboard inc xnuHber of «cte^tB var ?GET FIRST BYTE OF PASSWORD ; CHECK FOR Zmo !IF SO CONTIKUE WITH POST ; IF NOT CONTINUE WITH THIS blOfl EJtT OVERIT; PRnJtB< ■ PRINTB-! • PRINTB< * pRIIiTS< ' pRirfrB< ' PRINTB*' PRINT0<* PRtNTBc* LOOPlAi LOOPl! PC SECUEITV p;^S SWORD UTILITY COFYRICHT HATRONICS 1991 M3h io> SI3,10> M3.ig> 10> PLEASE ENTER YOUR PASSWORD FOLLOWED BY THE ENTER KEY mV BX,0Oh CALL CI CMP AL.OEh JNE GOOD DEC EX JE LOOP! CMP AL.ODh JE CHECK HOV BYTE PTR DSiNEHMORDlBXLAL INC B3t J HP LOOPl CALL CUECKl CKP DX,1 JE OK CMP CL.O JE loops JMP LOOPIA MOV M*, 0 FTh M3,10? z«ro bx k^yboai^d data check for CR *di3 CO ^nt^red a c ring buicp pointer mare Input l9ta chtck paeeword it I thfin good pattcwd continue bio fican if itro no more chance B interfere with adjacent cards. After mounting all compo- nents. (Fig. 2 ) select a base ad- dress (COOO or EOOO) and install the appropriate header pin. Then select a starting address on SI as shown in Tkble 1. Remove power from your PC, insert the card in an empty ex- pansion slott then reboot. You haven't installed the software yet. so the board will not ask you for a password. Copy the software to a directo- ry on your hard disk. Then run INSTROM.EXE. specifying GENERAL. IMG as the file, along with your selected address. Then reboot. This time you TABLE 1— PASSWORD ADDRESSING JU1 IC3 103 PC Jumper Output Pin Address EOOO YO 15 EOOO EOOO Y1 14 E400 E800 Y2 13 E800 ECOO Y3 12 ECOO COOO Y4 11 DOOO COOO Y5 10 D400 COOO Y6 9 D800 COOO Y7 7 DCOO COOO Y2 13 C800 COOO Y3 12 CCOO should see a sign-on message and a request to enter your password. Enter the default password ("avento''), and you FOREVER! PRINTS*' SOftRY ] E ' OUT 2tHjAL OUT 20H,AL JMP FOREVER jtr EEC BYTE VTR PSrCCUHT MOV CLpBYTE PTR 0S;COUI*T MOV DX.O E»Df> j;ADD CR to ecrlng 7 point K.O new jpoint to fixed! paeswd f CLEAR AX ;gst byte newword ;aet byte password J check for end of string finu fit btt c k bytefi natch J bad paeewQrd jcycle pasevord :cycle nevpasavd J check nesct bytft ;a I? BLicceeg ;dec try count ;get try count ;a a s fail J Copyright (e) FOSCO - All Rights ReBftrved i ; (Module Kafue: Qbjex Library gonsoie Input funictlon t Vftrsiotit 1.00 Author) POSCO Date: i-l-8& J i pi l^nasie : o J ci . a £BI ; Lang^agei KS HASH ; Functional I>«Ecription] J Version History: ; unsized ci (void) ; ; .laodel sioallpC ; .code cl proc NEAR xor axpax int I6h ret ci sndp should be able to continue the boot process. lb use the board for your own BIOS extensions, use Listing I as a model: GENERAL.ASM is the corresponding source file. Assemble your code to create an EXE me. Then read that EXE iile into memory using DEBUG, Determine the number of bytes the ROM image should contain, then write the file to disk starl- ing from address OlOOh. Listing 2 shows how to create a 2048- byte (080 Oh) ROM image by reading in a file called GEiNER- AL.EXE and writing out a file called GENERALJMG. LISTING 2— DEBUG SCRIPT C>DEBUG GENERALEXE -N GENERAL. IMG -RCX CX 0351 :0800 -W0100 Writing 00800 bytes -Q G> Creating ROM BIOS exten- sions is not easy. The tech- niques described here can greatly simplify the mechanics , enabling you to concentrate on the real programming task. R-E This cigarette is out. Or is it^j Oniy you can prevent ioKst fiies. A hi)bc kfv^t c{ ehr USOA {^c«Qi Snvkr lal ]fau I i 55 THOMAS R, FOX EVEN THE LATEST AND MOST So- phisticated automobiles have an Achilies heel — the battery. Improvements in lead-acid bat- teries have been glacial com* pared with advances in the rest of the car — regardless of the country of origin. Recent ad- vances In electronics have Im- proved engine and emission control, made anti-lock braking affordable, and have put high- quality entertainment s>^ terns into the passenger compart- ment. Unfortunately all of these improvements have added to rather than decreased the bat- tery load. If your car fails to start in your garage. Its usually just an ag- gravating situation. But if you stall out or can't get started at a vast shopping mall or worse yet* out along an interstate, the situation becomes more se- rious. And if you're unfortunate enough to be caught In a crime- stricken urban area or on any highway at night, you could be facing danger. Getting help takes time and can be expensive even under the best of condi- tions. The point is that it pays to know that your battery is in top form — even more if it's not! A weak battery is the most common cause of ari ail tb- mobiles failure to start. The battery remains the most failure-prone component in any automotive (and boat, for that matter) ignition system, A prop- erly maintained engine can last for hundreds of thousands of miles* but few lead-acid storage batteries are at top performance for more than about three years. Even that time will be shortened if you live in a northern climate where your car is exposed to long winter cold "soaks'* and hard starts. Don't think that j ust because you bought a new battery last month that it's immune to failure. However, batteries rarely fail without such warning clues as occasional slow crank- ing. Unfortunately many driv- ers are either unaware of these clues or. if they are aware, they put off recharging or replacing the battery until it Is too late. to tne rescue The CHanking Amp Es- timator (CFIAE) described here is a test instrument that will give you a reasonable estimate of your battery s power capacity. While CRAE is not a precision instrument, it will save you from being stranded in a hostile environment. Both the graph of relative power vs. temperature {Fig. 1) and the GW BASIC listing { List- ing 1) will with a knowledge of the ambient temperature, give you a reliable estimate of your battery's coId-cranklng ampere (CCA) rating. The BASIC pro- gram is capable of estimating the CCA of a battery at all nor- mal ambient temperatures if the CCA at one temperature is known. Both Fig. 1 and the CAR BATTERY TESTER BuHd this simple meter to estimate your car battery's cranking amps. i rn s a z 57 m 60 3 ^0 i S 60 50 40 30 61 D-CRAN (IMG PS -20 to 20 30 40 50 TEMPERATURE (DEGREES F) 60 70 FIG. 1— RELATIVE POWER CAPACITY \n a battefy at temperatures from -20T to + 80' F where 100 % available power is assumed. Cold-cranking amps (CCA) are read at a temperature of O'F. BASIC program are based on General Motors Corp. studies. CRAE's drain on your battery is only a slight 2.5 amperes, so It Is much safer to use than In- struments that test the load. Also, CRAE will not signifi- cantly discharge your battery if it is used as directed. Re- member that CRAE is not an ammeter so its readings will only give you an intelligent esti- mate of the potent ia! CCA of your battery without actually measuring it. After you have learned how to use CRAE, all you need is a dlg- ital voltmeter and a ther- mometer to keep you informed on the condition of your 12- volt car or boat battery — if it has a CCA rating from 150 to 1000. Coid-cranking amps g Cold cranking amps (CCA) is g the value for the amount of cur- rent a battery can deliver for 30 seconds at O^'F without drop- ^ ping below a specified cutoff ^ voltage. Figure 1 shows that the -| battery power output increases 2 significantly from OT to 80T In S fact, a battery rated at 600 CCA ^ (at OT) should be able to deliver 1/0,61 X 600 or 984 cranking amps at SOT! An approximate guide in de- 58 terminlng the CCA rating for a batteiy that will start an engine reliably at OT depends upon en- glne displacement, typically measured in cubic inches. How- ever, If your engine displace- ment is specified in liters> mul- tiply that figure by 61 to get cu- bic inches before using the following guide: • An eight-cylinder engine re- quires one cranking ampere per cubic inch of engine displace- ment. For example, to start an eight-cylinder 350 cubic-inch engine, the battery must deliver 350 CCA, • A six-cylinder engine has a CCA rating that is eight times the cubic-inch displacement per cylinder. For example, if a six-cylinder engine has a dis- placement of 231 cubic inches, the displacement per cylinder is approximately 39 cubic inches. Therefore, the battery must de- liver 39 X 8 = 312 CCA. • A four-cylinder engine has a CCA requirement that is twice the engine's displacement in cu- bic inches. For example, if a four-cylinder engine has a dis- placement of 180 cubic inches, the battery must deliver 360 CCA. If the ambient temperature is consistently below OT the bat- tery should have a CCA rating that is 20% higher than that which would be calculated for warmer conditions. In addition to CCA, there are other battery ratings in use to- day. For example, the MCA, for marine cranking amps, is a rat- ing developed for boat batteries that is based on 32 T instead of OT for CCA. An MCA rating for the identical CCA-rated battery is typically 25 to 30% lower. Another specification is re- serve capacity given in min- utes. It describes a battery*s ability to continue supplying power to the engine and ac- cessories if the car's charging system fails. That test drains the battery at a 25 ampere rate until the battery voltage drops from more than 12 volts to 10*5 volts, A 12-volt batteiy model Most text books show a 12- volt storage battery equivalent circuit either as an ideal 12-volt source or as that source in se- ries with a small resistance, per- haps 20 milliohms or less. An ideal voltage source provides a constant voltage regardless of current flow. It can deliver infi- nite current and infinite power. Unfortunately, there is no such thing as an ideal voltage source. The equivalent circuit for a battery shown in Fig, 2 is a sat- isfactorj^ model for the design of a CCA meter. However, the more realistic equivalent circuit shown in Fig. 3 includes a large capacitor and an additional re- sistor. That model accounts for changes in battery output with respect to time. An even more elaborate model would include a time- and cur- rent-dependent voltage source as well as time-dependent re- sistors and capacitors. How- ever, accounting for all of those additional variables would com- plicate the design of a simple, easy-to-use meter. Moreover, taking into account all of those additional variables would add little to the accuracy of the meter. How CRAE works CRAE*s objective is to esti- mate the size of R^^r shown in Fig, 4, There Is an inverse relationship between this re- sistor and battery capacity: the RG. a— EQUIVALENT CI RCUIT FOR a 12- volt lead-acid storage battery. R^f^j llmfts the battery current. Ra3—CRAE EQUIVALENT CI RCUIT for a 12- volt lead-acid battery. The one-min- ute test reduces the measurement error caused by Cb and Rq. smaller the value of Rje^'p the higher the battery's capacity; In the absence of Cj^ and R,^. could easily be estimated by ap- plying a load to the battery, mea- suring voltage and current » and making a few calculations. (CRAE does this for you auto- matically) However, It is first necessary to discharge C3, the reason that CRAE has a timing circuit. There are three basic parts to CRAE: The first, the voltage- measuring circuit, is a sensitive voltmeter that measures an ad- justable voltage from 11.9 to 12.5 volts. The second is a solid- state, constant' cur rent load that is adjusted to draw 2,5 am- peres load regardless of the volt- age. The third is a one minute timer that lights an LED to indi- cate measurement readiness. The voltage-measuring cir- cuit consists of op-amp ICl-a VA LM324) connected in a differen- tial amplifier circuit. The volt- age reference for this circuit is the 5-volt regulator 1C2 (LM2931Z), Resistor R13, the MAXADJ potentiometer, trims this reference voltage to max- imize voltage readings under no-load conditions. Resistor R3 is a PC- mount trimmer that ad- justs current flow through the meter and is a sensitivity con- trol on Fig. 4, Resistor R20 is a IK PC- mount trimmer that sets the meter's zero point (0.05 milli- ampere}. Resistors R5 and R6 raise the meter s negative termi- nal abov^c ground level, allowing the meter to be zeroed. Diodes D2 and D3 protect the meter* and Dl protects other sensitive parts of the circuit from acci- dental damage when the test leads are first connected to the battery The primary component of the constant-current load is Q2. When momentary two-position toggle switch SI is switched to the TEST position, current flows through gi s emitter circuit be- cause ICl-c provides base cur- rent. That emitter current also flows through Q2s base circuit* resulting in considerable cur- rent flow. Resistor R17 both di- rectly and indirectly controls the constant current. As in any transistor with an emitter resistor. Q2s current is essentially constant because, as emitter current increases, emit- ter voltage follows. This means that Vj3E- and V^^^r are smaller* thus tending to reduce emitter current. Nevertheless, this effect is not sufricient to provide a constant-current load. Op- amp ICl-c completes that task. Moreoven ICl-c helps to provide a near ideal constant current load, and it also simplifies load- current adjustment. (-^)ALUGATOR QtIP (BUCK) FIG. 4^SCHEMATtC FOR CRAE showing contact points for external connections. RG. &-PARTS*PLACEMENT DIAGRAM for printed crrcult board of CRAE. Examination of the sche- matic reveaJs that the inverting input is connected through R16 to 92s emitter. As Q2"s emitter current increases, the voltage at the inverting input of ICl-c in- creases, resuking in a lower voltage output at pin 8 and less current at Ql s base. That causes a reduction In current at 92 's base and the resulting de- crease in Q2 s collector and emitter current. R14 adjusts the voltage on ICl-cs non-inverting input, and thus provides ad- justment for the current through Q2*s emitter. The timing circuit was de- signed so that the timing period would vary with voltage. (Low readings on CRAE's meter are related to low batter}' voltage and longer timing periods,) This, in part, compensates for a fully charged (high open-circuit voltage) battery's tendency to show somewhat smaller CCA values than if it were slightly discharged. The timing circuit consists of ICl-b, C4, and R18. When SI is in the test position, C4 starts to charge through resistor R18. When the voltage across C4 ex- ceeds 5 volts, the op-amps out- put switches "on" and lights LEDl, Construction The most expensive compo- nent in CRAE is the moving-coil ammeter ML capable of reading 1 milliampere. A meter with this rating could could cost from $ 10 to more than $50, depending upon size, A custom-made PC board is not required because CRAE is a simple low- frequency instru- ment, but it will make assembly easier and faster, perhaps in as short a time as a few hours. However if you assemble CRAE rapidly, be sure to allow extra time for thorough testing and calibration. Figure 5, the component- mounting guide, should be used together with the sche- matic in Fig. 4 when building CRAE to avoid problems. Meter Ml, switch SI, LEDI and poten- tiometer R13 are mounted on the front panel of the case: all other parts are mounted on the PC board. Be sure that the heat sink is in place when soldering Q2. The heat sink with Q2 at- tached is mounted on the foil side of the board. On the com- ponent side, wires are con- nected from Q2s base and emitter to the PC board with insulated jumper wires as shown in Fig. 5. Notice that R17*s power rating is listed in the parts list as 5 to 7.5 watts. Calculations indicate that the resistor must dissipate 6.25 watts. However, because the current generally flows in- termittently only for a minute at a time, a 5-watt resistor can be used. (An effective 1-ohm re- sistor can be made by winding 40 feet of 24-gauge copper mag- net wire around tlie outside of a large-value power resistor.) Be sure to leave at least a ys-inch gap between R17 and the circuit board to permit air to circulate for cooling. Crimp and solder flexible two- conductor electrical lamp cord to each large alligator clip. One conductor from each clip is at- tached to the voltage-measur- ing circuit, and the other conductor is attached to the load circuit. That 4-wire ar- rangement prevents a voltage drop on the test lead wires from causing measurement errors. Those conductors should be 18- gauge or larger stranded copper Solder one conductor of the cord from the positive alligator clip to TPl on the circuit board and solder or crimp the second conductor to pin 4 of switch SI as shown in Fig. 4. (Refer to Fig, 6 for the pin numbering system of the switch as shown from the rear,) Similarly solder one con- ductor of the cord from the negative alligator clip to TP2 on the circuit board, and solder or clip the second conductor to a circuit-board ground such as that at the lower right corner of the foil on the circuit board. Connect a wire from the " -I- ter- minal of Ml to TPS and a wire from the " terminal to TP4. Also connect some hookup wire from the left terminal (viewed from the rear) of R13 to TPS and a wire from the center terminal to TP6. In performing the following steps refer to Fig. 6 . switch Si's pin-numbering guide. (The pin numbering shown is for the switch In the Parts List.) Con- nect a wire from pin 2 of S i to a circuit board ground. Also, con- nect wires from pin 3 to TP9 and pin 5 to TPS. Finally, connect a wire from the LEDs anode (long lead) to TP7, and a wire from LED's cathode (short lead) to a circuit ground. (The LED should be a high-efficiency GaA.sP or GaP lamp that draws minimal current because the circuit is sensitive to small volt- age changes,} You'll want to calibrate the meter and. perhaps relabel the meter's face with the term "Esti- mated Cranking Amp"mark- ings, for a more professional appearance. T^ble I is a set of data for guidance in calibrating the meter. The photograph shows the end result. RG. 6— REAR CONNECTIONS for SI, a 3- way toggte switch. 8 o SOLOER-SIDE FOIL PATTERN for PC board shown actual size. There are several ways to label a meter face. In one you can use a PC and an appropriate com- puter-aided design program to relabel the graduations and set up the estimated cranking amps legend. That can be printed out on adhesive- backed paper or plastic with a laser printer for direct application. The only drawback to this meth- od Is that the paper might be thick enough to interfere with the meter *s moving needle. Another method is to erase the numbers on the meter face with a pencil or ink eraser, and TABLE 1— GUiDETO LABELING AMMETER Milliamps Cranking Amp Markings 0.00 1 50 (or below) 0.30 200 0.48 300 0.60 450 0.70 650 0.80 800 0.94 1000 1.00 Infinite LISTING 1— PROGRAM FOR ESTIMATING CRANKING AMP CAPACITY 1 "THIS GW BASIC PROGRAM ESTIMATES THS CRANKING RttP CAPACITY Of A 12V LEAD- ACID 2 'STORAGE BATTERY AT MOST PRACTICAL TEMPERATURES ASSUMING YOU SUFPL^f IT DATA OF 3 "THE CRANK IttC MlP CAPACITY AT A SPECIFIC TE21PERATURE . IF ALL TOU KNOW 2S THE A 'HANUFACrJRER'S "CCA" RATiNO, HAKE SLIlS TOSJ ENTER '0' WHEN ASKFD 5 ' *HNat ia the temperature of the bettery, in degrees FJ' 10 tWPtrr *What is the teaiperaturo of the battery^ in degrees F'jTFOT 15 IF TFOT>120 GOTO 100 16 IF TFOT>B0 T!1£*J TFOT-80 20 INPUT ; "EstiMted Crenitlng Ampa nt this tcmporflture'' ;CAOT 30 PRINT "What temper dture due you ^ant the new (setia^tbe for cranScing onpA?" 40 INPUT "PRESS REltlRN FOR 0 F.(Thifl nill ^Ivc yOu the CCA>";rFNT 4 5 IF TFNT»120 GOTO lOO 4g IF TrNT*80 TffEN TrHT"$0 50 LET KTFOT«, 61+, 00Q2»TFOT-, 00004 1?*TF0T*TF0T 60 LST KTI''NT".61+*O0a2*TFNT'-OG0O417*TFKT*TFNT 70 LET CANT'KTFNTMCAOT/KTFOT) 80 PRINT "E^tiEiatiKt Cranking Ajupa at ''rTFNTf"r io CI51T{CAWTJ 90 END 100 PRINT "Storage batEarles should cot be expo»ad to this high d t«Bip«raturft! 110 ENE> then use dry-transfer lettering to relabel it. However you can simply use a soft pencil to add the cranking amp markings to the meter's markings. Double-momentary toggle switch SI. the maxeinfjadj potentiometer R13 and LEDl should be mounted on the front panel. Potentiometer R13 can be a stock single-turn potenti- ometer, but a multiturn potenti- ometer with dial makes CRAE easier to use. In labeling this potentiometer on the panel *'max'* stands for maximum, "inf'means infinite and "adj "means adjust. See the pho- tograph of the front of the in- strument. 7^ sting and calibration First, preset all potentiome- ters (R3, R13, R14, and R20) to their center positions. Next, set the output of a regulated power supply capable of at least 12,6 volts with a digital voltmeter (with minimum 0,5% DC volt- age accuracy,) If a regulated power supply is not available, substitute a fully charged 12- volt storage battery with a 100- ohm potentiometer across the terminals. The desired voltage can be taken from the center wiper arm. Connect the positive alligator clip (red) to the supply's positive terminal and the other clip to the negative terminaL Do not use the test switch at this time! Slowly increase the supply's voltage for a 12. 5- volt reading on the DC volts scale of a digital multimeter. Set R3 for a max- imum (I milUampereJ reading on meter ML Now lower the volt- age to 1L9V and adjust R20 for a 0,05 milliampere reading. Again apply 12.5 volts and ad- just R3 and/or R20 to obtain a 1,0 milliampere reading. Repeat this step for 1L9 volts. After sev- eral adjustments of R20and R3, Ml should register LO mllliam- peres when the voltage at the alligator clips is 12.5 volts and 0,05 miUiamperes when the voltage is 11,9 volts. The DMM should then be used to set R14 for a 2,5 ampere current flow through R17. Con- nect CRAE's alligator clips to a 12-voU storage battery or a 12- volt source that can deliver at least 5 amperes. (Be sure the red clip is connected to the plus ter- minal and the black dip to the negative terminal.) Next place the DMMs leads across the 1- ohm power resistor R17 and ad- gj Just R14 for a 2,5-volt display on S the DMM, (You are actually ad- ^ justing the current for 2.5 am- peres flowing through R17J. I This completes the basic cal- ^ ibratlonofCRAE, -| If the meter faceplate con* S version table in Ikble 1 Is used, M CRAE should have an accuracy ^ better than 20%. The prototype CRAE was calibrated and tested with four different batteries of known CCA capacity. TXvo bat- 62 teries were new (600 CCA and PARTS LIST All resistors are 1/4-watt, 5%, un- less otherwise indicated. R1— 23,700 Ohms. 1 4-watt, 1% R2— 20.000 ohms, 1/4-watt, 1% R3--500 ohms PCB trimmer R4 — 47 ohms R&— 470 ohms R6— 68 ohms R7, R11— 10.000 ohms R8 — 4700 ohms R9 — 1000 ohms R1 0—270 ohms Rt2— 100,000 ohms R13— 5000 ohms potentiometer (panel-mount) R14— 2500 ohms PCB trimmer R15— 150 ohms R16— 33,000 ohms R17— 1 ohm, 5.0 to 7.5 watt R18— 10 megohm R19— 15,000 ohms R20— 1000 ohms. PCB trimmer. 15 turn Capacitors CI— O.In-F, 25 volts C2— IOh-F, 25 voirs, electrolytic C3— 220fiF, 16 volts , electrolytic C4— lOjiR 25 volts + /- 10%, tan- talum Semiconductors 1C1— LM324 quad op-amp 102— LM2931Z 5-volt voltage regulator Ql— 2222A NPN transistor Q2— 2N3055 NPN transistor LED1 — Light-emitting diode (High* efficiency GaAsP on GaP)D1— IN4001 silicon rectifier D2— IN914 silicon diode 03— IN5817 schotlky barrier rec- tifier Other components St— DPOT momentary action with off at center Ml— Panel meter, moving coil. 0 to 1 mA. Miscellaneous: two alligator clips (l-inch jaw length), two lengths of twO'Condoclor parallel flexible 18 AWG stranded copper lamp cord with PVC or rubber insulation (ap* prox, 3 feet long), PC board, case— Radio Shack Cat. No, 270-232 or equi valent, control po* tentiometer knob, aluminum heat sink, LED mounting hardware insulated tiook-up wire, solder etc, 165 CCA ratings, respectively), one was of average age {410 CCA), and one was older but still functional (400 CCA), The batteries were tested with com- mercial test equipment which confirmed the battery manufac- turers ratings for the three new- er batteries. The old 400-CCA batlei^^ test- ed 420 CCA at 50^ F with com- mercial equipment. This sug- gests that Its true rating is about 280 CCA and that its ser- vice life is probably at or very close to its end. While only four batteries were in the test sam- ple, CRAE was more extensively tested than this w^ould imply be- cause the tests were made at dif- ferent ambient temperatures on each battery. The accuracy rating of CRAE can be increased if you calibrate it with the output of three bat- teries of known capacity. Ac- curacy of calibration can also be improved if CRAEb results are compared to those of a commer- cial battery tester and adjusted accordingly You can also increase CRAE's accuracy by connecting it to a battery whose cranking amp ca- pacity is knouTi, and then ad- justing trimmer R14 so that CRAE's meter reading equals that a batterys of the battery Remember that cranking amp capacity changes with tempera- ture. How to use CRAE CRAEs reading will be most accurate when the open- circuit battery voltage is between 12 A and 12,6 volts. Do not use CRAE on an uncharged battery (open- circuit voltage below 12.2 volts) or a new freshly charged battery (open-circuit voltage above 12.65 volts), because the read- ings will be erroneous, lb avoid starting problems, replace any battery whose open-circuit volt- age falls below 12.2 volts within minutes of charging. Open-cir- cuit voltages should be taken under no-load conditions. That usually requires that the ground cable be disconnected from the terminals of the bat- ler>' before it is tested. If you want to test a new, re- cently charged battery dis- charge it slightly for a few hours at a discharge current of a few amperes. A safe way to do this is to make up a simple load by sol- dering insulated wires to the Continued on page 71 PHOTOSENSITIVE DEVICES Learn to use photoconductive cells, photodiodeSf and phototransistors in practical light'Controlled circuits. RG.i— CUTAWAY VIEW of a photocell or !ight-dependent resistor (LDRJ, RAY M. MARSTON WE WILL LOOK AT LlGm'-SENSmVE devices In ihis article and find out how I hey can be used In v^arious practical control cir- cuits. Light-sensitive devices Include photocells, pho- todiodes, and phototransistors. Visible and infrared light (or the absence of that light] can trig- ger many different kinds of cir- cuits for the control of alarms, lights, motors, relays, and other actuators. Light-sensitive de- vices, sometimes called pho- toelectric transducers, alter their electrical characteristics In the presence of visible or in- frared lighL Photocell basics. Photocells are also called by many other names including photoconductive cells, light-de- pendent resistors {LDR's), and photoreslstors. They axe varia- ble resistors with an extremely wide range of resistance values (up to hundreds of orders of magnitude) that are dependent on the level of incident light. Re- sistance in photocells varies in- versely with thestrengthorilght that falls on them. In other words, resistance is very high in the dark, but low under bright light. Figure I is a cutaway view of a typical photocell showing the pattern of photoconductive ma- terial deposited in the serpen- tine slot separating the two electrodes that have been formed on a ceramic insulating substrate. This pattern max- imizes contact between the crystalline photoconductive material and the adjacent metal electrodes. The photoconductive materi- al is typically cadmium sulfide (CdS] or cadmium selenide {CdSe)> The selection of the ma- terial and the thickness and width of Us deposition deter- mine the resistance value and power rating of the device. The two-terminal assembly is en- closed in a metal or opaque plas- tic case with a clear glass or plastic window over the photo- conductive material. Figure 2 is the schematic symbol for the photocell Photocells are made with di- ameters from about one-eighth Inch (3 mm) to over one inch (25 mm): the most popular devices have diameters of about three- eighth inch ( 10 mm). The small- er units are suitable for applica- tions where space is limited, such as in card-reading applica- tions, but they have low power- dissipation ratings. Some pho- tocells are hermetically sealed to withstand the effects of de- manding environments. Figure 3 compares the re- sponse of photosensitive de- vices characteristics with that of the human eye. Relativ^e spec- tral response is plotted against wavelength from 300 to 1200 nanometers (nm). The bell^ shaped human eye response cur\^e shows that the eye is sen- sitive to a relatively narrow band of the electromagnetic spectrum, between about 400 and 750 nm. The curve peaks in the green light region at about 550 nm and extends down into the violet region (400 to 450 nm) at one end. and up into the dark red light region ( 700 to 780 nm) at the other end* Figure 3 shows why cadmium sulfide (CdS) photocells are so popular for ligh(-controlled cir- cuits; the CdS spectral response curve peaks near 600 nm* and it closely fnatches that of the human eye. By contrast, the re- sponse cur\^e for cadmium se- lenide (CdSe) peaks further out at about 720 nm. However, CdSe is also sensitive to most of the visible-lighl region, A typical CdS photocell characteristic cur\x is shown in Fig. 4. Its dark resistance is about live megohms. This value falls to about 600 ohms at a light intensity of 100 lux. t>pical of a well illuminated room and BLUE YELLOW RE VIOLET \ GREEN /ORANGE / to about 30 ohms at an inten- sity of 8000 lux, typical of bright sunlight. (The lux is the SI unit of illuminance produced by a lu- minous flux of 1 lumen uni- formly distributed over a sur- face of 1 square me ten) Commercial photocells have good power and voltage ratings, similar to those of conventional resistors. Power dissipation rat- ings could be between 50 and 500 milliwatts, depending on detector [uaterial. Their only ULTRAVIOLET" 1,0 0 0-8 a. to UJ 5 0.6 •I cc 1— ^ OA CO UJ 1 0.2 UJ a: 0 -VISIBLE REGION- - INFRARED- ''V ^ rv 1 \ r \ ' \ \v ILICON f \ \ — = Vr^RE CEPTOBS \ \ \Y CAD \fllLlM NIDE \ y \i PHOt CADMIl DCELL IM 7 \ \ 1 \ I \ 1 ■ SULRE PHOTOC >r ELL 300 400 500 1200 fiOO 700 BOO 900 1000 UOO WAVELENGTH (NANOMETERS) FIG. 3— ^CHARACTERISTIC CURVES of photosensitive devices compared with the response curve of the human eye. TOK IK too 10 WELL F LIGF ^TE 3 SI m\i Ml IGI IT \ \ 1 to too IK LIGHT IHTENSmr (lUX) 10K FIG. 4— CURVE OF RESISTANCE versus tight mtensity for a typical pholocell with a 1 0- mm face diameter. FIG, 5— SIMPLE NON-LATCHING light- activated relay switch. significant drawbaciis are their slow response times. Cadniium- selenide photocells generally have shorter time constants than cadmium-sulfide pho- tocells (approximately 10 milli- seconds versus 100 mlHise- conds). They afso offer lower resistance values, higher sen- sitivities, and liigher tempera- ture coefficienls of resistance. Photocells arc included in photofjraphic exposure meters, lighl- and dark-ac t i va ted switches for controlling safety lights, and intrusion alarms. Some light-aclivatcd alarms are triggered by breaking a light beam. There are even light-re- flective smoke alarms based on photocells- Figures 5 to 20 show practical photocell circuits; each will work with almost any photocell. Photocell light switches Figures 5 to 10 illustrate prac- tical light-activated switch cir- cuits with relay contact outputs that are based on the photoeelL The simple circuit shown in Fig. 5 is designed to react when light enters a normally dark space such as the inside of a cabinet or closet. The photocell Rl and resistor R2 form a volt- age divider that sets the base bias of Ql. Under dark condi- tions, the photocell has a high resistance, so zero bias is ap- plied to the base ofQl; in this state, Ql and the relay RYl are off. Wiicn a sufficient amount of light falls on the photocell, its resistance drops (o a low value, and bias is applied to the base of QL That bias activates RYl, and its contacts can control external circuitiy. FIG. 6— SENSITIVE SELF-LATCHING light-activated relay switch. RG. 7~SIMPLE DARK-ACTIVATED relay switch. <3 0V FIG. 8— PRECISION LIGHT- sen si live relay switch. R5 equals R6 a! normal light level. FIG. 9— PRECISION DARK-ACTIVATED switch with hysteresis. R6 equals R7 at normal light level The simple Fig. 5 circuit has for sensitivity adjustment. Fig- low sensitivity and no provision ure 6 illustrates how these drawbacks can be overcome with Darlington-coupled tran- sistors Ql and Q2 replacing Ql, and the use of a potentiometer R2 for sensitivity control, re- placing fixed resistor R2. The diagram also shows how the cir- cuit can be made self-latching with the second set of relay con- tacts. Normally-closed pushbut- ton switch SI permits the circuit to be reset (unlatched) when required. Figure 7 shows how a pho- tocell can form a simple dark- activated relay that turns on when the light level falls below a value preset by potentiometer Rl. Resistor R2 and the pho- tocell R3 form a voltage divider. The voltage at the R2-R3 junc- tion increases with falling light. That voltage » buffered by emit- ter-follower QL controls relay RYl with common-emitter am- plifier Q2 and current-limiting resistor R4, The light trigger or threshold levels of the circuits shown in Figs. 6 and 7 are susceptible to variations in supply voltage and ambient temperature. Figure 8 shows a very sensitive precision light-activated circuit that is not influenced by those varia- bles. In this circuit the pho* tocell R5. potentiometer R6, and resistors Rl and R2 are con- nected to form a Wheatstone bridge, and op-amp ICl and the combination of transistor Ql and RYl act as a highly sensitive balance-detecting switch. The bridge balance point is inde- pendent of variations in supply voltage and temperature, and is influenced only by variations in the relative values of the bridge components. In Fig. 8. the photocell R5 and potentiometer R6 form one arm of the bridge, and Rl and R2 form the other arm. Those arms can be considered as voltage di- viders. The R1-R2 arm applies a fixed half-supply voltage to the non-in verting input of the op- amp, while the photocell-poten- tiometer divider applies a light- dependent variable voltage to the inverting pin of the op-amp. To use this circuit, potenti- ometer r^6 is adjusted so that the voltage across the photocell and the potentiometer rises Dl r*^ iOK R2 R6| 0 R3 IOK IC2 MA741 R4 12K R5 ?7K Q1 ZH37G2 -N- D2 D3 1N4001 RY^ 12V 12Gn O "O OUT O FIG. 10— COMBINED LIGHT/DARK-activated switch with a single relay output Vafue of R2 equals R6 at norinal light Jevel. changes in light-level that are too small to be detected by the human eye. The circuit can be modified to act as a precision dark-activated switch by either transposing the inverting and non-inverting input pins of the op-amp, or by transposing the FIG. 11— SfMPLE L?GHT-ACT(VATED alarm belL fractionally above that across Rl and R2 as the light intensity rises to the desired trigger level. Under that condition^ the op- amp output switches to nega- tive saturation^ which turns on Ql and thus RYL When the light intensity falls below that level, the op-amp output switches to positive saturation, and Ql and the relay are turned off. The circuit in Fig. 8 is so sen- sitive that it is able to respond to photocell and the adjacent po- tentiometer The circuit in Fig. 9 also shows how a small amount of hysteresis can be added to the cireuil with the feedback re- sistor R5 so that relay KY! is actuated when the light level falls to a preset value. However the relay is not de-actuated again until the light intensity increases substantially above that value. The hysteresis mag- nitude is inversely proportional to the value of R5t but it is zero when R5 is open circuited. Figure 10 shows how a preci- sion light/dark switch can be made by combining op-amp light and dark switches. The switch activates relay RYl if the light intensity rises above one preset value of falls below an- other preset value. Potentiome- ter Rl controls the dark level, potentiometer R2 controls the FIG. 13— PRECISION LIGHT^ACTIVATED alarm beJL Value of R5 equals R6 at normal light level. is 5 o Z 0" Rl 2.2K + 6TO+14V Re 470K Qt zmim R2 1K R3 IK 1M4Q01T R4 470Q SCRt C106V1 om 66 FIG, 12— IMPROVED LIGHT- ACTIVATED alarm bell with self-latching. supply voltage, and potentiome- ter R3 controls the Ught level. To organize the circuit shown in Fig, 10, first preset potenti- ometer R2 so that about half the supply voltage appears al the juriction between photocell R6 and potentiometer R2 when the photocell is illuminated at its normal intensity level. Potenti- ometer Rl can then be preset so that RYl is actuated when the light intensity falls to the desir- ed dark level, and potentiometer R3 can be adjusted so that RYl is actuated at the desired brightness level. In the circuits shown in Figs. FIG. 15— SELF-LATCHING LIGHT-actlvated alarm with monotone output. . le^BOOSTED-OUTPUT PULSED-tone light-activated alarm 8 to 10. the resistance values of the series potentiometers should equal Ihe photocells re- sistance values at the normal light level of each circuit. Bell-output photocell alarms The light-activated photocell circuits in F^lgs. 5 to 10 all have relay outputs that can control many different kinds of external circuits. In many light-acti- vated circuit applications, how- even the circuits must trigger audible alarms. This response can also be obtained wi thout re* lays as shown in Figs. 11 to 17. Figure 11 shows a simple light -activated alarm circuit with a direct output to an alarm bell or buzzer The bell or buzzer must be self-interrupting and have an operating current rat- ing less than 2 amperes. The supply voltage should be 1 .5 to 2 volts greater than the nominal operating value of the bell or buzzer. Photocell R3 and re- sistor R2 form a voltage divider Under dark conditions, the photocell resistance is high, so the voltage at the junction R3 and R2 is too small to activate the gate of the silicon-controlled rectifier SCRl. Under bright light conditions with the pho- tocell resistance low, gate bias is applied to the SCR which turns on and activates the alarm- In the circuit of Fig. H. keep in mind that although the SCR is sel Watching, the fact that the alarm is self-interrupting en- sures that the SCR repeatedly unlatches automatically as the alarm sounds, (The SCR anode current falls to zero in each self- Interrupt phase.) Consequently the alarm aulomatieaUy turns off again when the light level falls below the circuits thresh- old level. The circuit of Fig. 11 has fairly low sensitivity and no sen- sitivity adjustment. Figure 12 shows how that drawback can be overcome: Potentiometer R6 replaces a fixed resistor and Ql is inserted as a buffer between photocell R5 and the SCRl gate. The diagram also shows how to make the circuit self- latching by wiring R4 in parallel with the alarm so the SCR anode current remains above zero as the alarm self- interrupts. Switch 31 per- mits the circuit lo be reset (un- latched) when required. Figure 13 shows how to make a precision light-alarm with an SCR-actuated output based on a Wheatstone bridge formed by the photocell R6» potentiometer R5. and op-amp ICl, The op- amp l^alance detector provides precision control. That circuit can be converted into a dark- activated alarm by simply trans- posing the photocell and poten- tiometer. Hysteresis can also be added, if required. C2 01 km I \ m >m in,] TO 50O -ODV ^ *HV1 ^^LDR AT NO RMAL i I G HT LEVEL FIG. 17—PRECISION UGHT-aclivated pulsed-lone alarm with hysteresis. Value of R7 equals R8 at normal light level. +6T0 4-14V IMPI LENSES UGHT 4r 01 TK4001 ST ^1, RESET Ami SGR1 'ClDflYI RG. 18^S1MPLE LIGHT-^BEAM alarm with selMnterrupting bell output. 2 s I UJ 6B PIG. 19— CUTAWAY VIEW of a light- reflection smoke detector. Speaker- output alarms Figures 14 to 17 show dif- ferent ways of using CMOS 400 IB quad 2-inpul NOR-gate !Cs to make light-activated alarms that generate audible outputs with loud speakers. The 400 IB is available as the CD4001B from Harris and from Motorola, National vScmicon- FIG. 20— REVERSE-BIASED DIODE circuit. ductor, Signetlcs and others under various designations that include 4001B. The circuit of Fig, 14 is a dark- activated alarm circuit that gen- erates a low-power 800-Hz pulsed-tone signal at the speak- er nor gates ICl-c and ICl-d are wi red as an 800-Hz as table mul- tivibrator that can feed tone sig- nals into the speaker from QL It is gated on only when the out- put of ICl-b IS low. NOR gates ICl- a and ICl-b are wired as a 6-Hz as table circuit that is gated on only when its gate pin 1 is pulled low. (Pin 1 is coupled to the volt- age divider formed by photocell c d FIG- 21— SCHEMATIC SYMBOL for a photodtode. FIG. 22-PHOTODIODE WITH resistor between diode and supply. FIG. 2a— SCHEMATIC SYMBOL for a phototransistor. R4 and potentiometer R5.) The action of the circuit is as follows; Under bright light con- ditions, the voltage at the junc- tion of the photocell R4 and potentiometer R5 voltage is high, so both astable circuits are disabled and no output is generated at the speaker Under dark conditions » the photocell- potentiometer junction voltage is low, so the 6- Hz astable cir- cuit is activated, gating the 800- Hz astable circuit on and off at a 6-Hz rate. As a resuit. a signal from Ql produces a pulsed-tone in the speaker. The precise gating level of the 4001B IC is determined by its threshold voltage value, whicli is a fraction of the supply volt- age — nominally 50%. Tliat val- F^G. 24— ALTERNATIVE PHOTOTRANS ISTOR cfrcuits. na 2S— PHOTOTRANSISTOR used as a photodiade. FIG, 26— VARIABLE SENSITIVITY pho- totransfstor circyit. FIG. 27— SCHEMATIC SYMBOL for a photodarlington. ue might vaiy from 30% to 70% in individual devices, but gat- ing points of these IC's are gen- erally stable. The Fig, 14 circuit provides sensitive dark-acti- vated alarm triggering. Figure 15 is a schematic of a self-latching light-activated alarm with an 800-Hz monoto- ne output. In this circuit, ICl-c and ICl-d are also wired as a 0 MOOmH laoK: D1 . CI \24nF : m 470K . €2 : R2 Q1 2N37Q4 + 12V FIG. 28— SELECTIVE INFRARED preamplifier for SO-Hz operation. FIG. 29— SELECTIVE PREAMPLIFIER for 20-kHz light-beam alarms. gated 800-Hz astable circuit, but ICl-a and ICl-b are wired as a bistable multivibrator with a normally high output. Under bright light conditions, the photocell-potentiometer junc- tion goes high and latches the bistable circuit into its alter- native state. As a result, the 800-Hz astable circuit is gated on to generate the monotone alarm signal. The circuit re- mains in that state until dark conditions return, and the bistable circuit is simulta- neously reset with SI. The light/dark operation of the circuits in Figs. 14 and 15 can be reversed by transposing the positions of the photocell and potentlomenter Each cir- cuit produces only a few miUi- watts of output power Figure 16 shows how the operation of the dark-operated circuit of Fig. 14 can be reversed to become light- operated by switching the posi- tions of the photocell and poten- tiometer The output power can be boosted with an additional output transistor Q2. This cir- cuit can operate from a 5- to 15- volt supply and with 25- to 50- ohm speakers. The output power can vary from 0,25 to 11.25 watts, depending on the voltage and impedance values. The circuits shown in Figs. 14 to 16 have adequate sensitivity levels for most practical applica- tions. However, if required, both sensitivity and trigger- level stability can be increased. That's done in Fig. 17 by insert- ing an op-amp voltage com- parator between the voltage divider junction formed by pho- tocell R7 and potentiometer R8 and gate pin 1 of ICt-a. Resistor R3 controls the hysteresis of the circuit* but it can be removed if hysteresis is not needed* Selection of photoceU circuits Photocells are widely used in alarms that are triggered by in- terrupting a visible light beam. They are also used in smoke alarms that are actuated when smoke particulates reflect light back to the photocell. Figures 18 to 20 show self- interrupting alarm-bell versions of those warning circuits- The Interrupted light beam- activated alarm circuit of Fig. 18 acts like a dark-operated alarm. Normally, the photocell is il- luminated by the light beam so its resistance is low and only low voltage appears at the junction of potentiometer R4 and pho- tocell R5. Consequently^ both the SCR and bell are off. When the light beam is broken^ pho- tocell resistance increases and a significantiy higher voUage ap- pears at the potentiometer-pho- tocell junction. Under this condition SCRl conducts and the alarm bell rings. Resistor R3 in series with switch SI self- latches the alarm. Figure 19 is a cutaway view of a reflective-type smoke detector. The lamp and photocell are mounted on one wall of the box whose open ends are covered with lids mounted on spacers. The openings provided by the spacers permit smoke to pass through the detector while while ambient light is excluded. An internal baffle prevents in* candescent lamp light from fall- ing directly on the photocell. The lamp acts as both a source of light and heat; the heated air in the box rises, creating air convection cur- rents that draw air in at the bot- tom of the box and cxpell it from the top. The inside of the box is painted matte black to elimi- nate reOections. If the air currents moving through the detector box are free of smoke, no light will fall on the photocell, and its resis- tance will be very high. Howeven if the air contains smoke, the particulates of that smoke re- flect light from the lamp back onto the photocell face, causing its resistance to decrease sharp- ly That resistance drop can trig- ger an alarm. Figure 12 is a practical control circuit that can be used in the smoke alarm shown in Fig. 19, Photodiodes put to use If a conventional silicon diode is connected in the reverse-bi- ased circuit of Fig, 20. only leak- age current will flow through the diode and no voltage will be developed across resistor RL Howeven if the case is removed from a conventional silicon di- ode to expose its PN junction, and the diode is then replaced in the same circuit, its pho- tosensitive properties can be observed. When the diode is exposed to light, its current could rise to as much as one milliampere. pro- ducing a voltage across RL All silicon PN junctions are photosensitive. Thus a pho- todiode is essentially a conven- tional silicon PN-Junction diode in a case with a transparent cover to permit light to reach its junction. Figure 21 shows its standard schematic symbol. In Fig. 22 the photodiode is reverse biased and its output voltage is taken across a series- connected load resistor Rl. That resistor could also be con- nected between the diode and ground as shown in Fig. 20. Photodiodes also have spectral response characteristics, which are determined by the doping of the semiconductor material. Figure 3 shows a typical re- sponse curve that applies for all silicon photoreceptors, a cate- gory which includes both pho- todiodes and phototransistors. While silicon photodiodes have lower visible-light sen- sitivity than either cadmium- sulphide or cadmium-selenide photocells, they respond faster to changes in light level. As stated earlien cadmium-sulfide and cadmium-selenide pho- tocells are best suited for ap- plications in visible light in which they are directly coupled and where relatively slow re- sponse lime is acceptable. By contrast, photodiodes are bet- ter suited for applications in the infrared region in which they receive AC signals and where fast response is required, Photodiodes are typically used in infrared re mote- control circuits, beam-interruption switches and alarm circuits. However, lead-sulfide (PbS) pho- tocells have characteristics that are similar to those of visible- light photocells except that they function only in the infrared re- gion. Phototransistors Figure 23 shows the standard phototransistor symbol. The phototransistor is a silicon bi- polar NPN transistor in a case with a transparent cover that al- lows light to reach its PN junc- tions. The device is normally used with its base pin open-cir- cuited as shown in both parts of Fig. 24. In Fig. 24a, the base- collector junction of the pho- totransistor is effectively re- verse-biased so it acts as a photodiode. The light-gener- ated currents of the base-collec- tor junction feed directly into the base of the device, and the normal current-amplification of the transistor causes collector current to flow as the output. That amplified current across Rl produces the output voltage. Phototransistor collector and emitter currents are usually similar because the base con- nection is open circuited, and the device is not subjected to negative feedback. As a Con- sequence, the alternative cir- cuit shown as Fig, 24b offers about the same performance as the circuit shown in Fig. 24a. The output voltage appears across Rl which is connected between the emitter and ground. The sensitivity of a pho- totransistor is typically one hundred times greater than that of a photodiode. Howeven Its useful maximum operating frequency of a few hundred kilo- hertz is proportionally lower than that of a photodiode's tens of megahertz. A phototran- sistor can be converted into a photodiode by connecting it as shown in Fig, 25. Alternatively, the sensitivity and operating speed of a pho- totransistor can be made varia- ble by wiring a potentiometer between its base and emitter, as shown in Fig. 26. With R2 open circuited, phototransistor oper- ation is obtained; with R2 short circuited, a photodiode re- sponse occurs. In practical applications of the circuits shown in Figs. 24 through 26. the Rl load value is usually selected as a compro- mise because voltage gain in- creases but the useful operating bandwidth decreases with the value of RL Also, the value of Rl value must, in many applica- tions, be chosen to bring the photosensitive device into its linear operating region. Darlington photo transistors consist of two transistors cou* pled as shown in the schematic symbol of Fig. 27. Typical sen- sftivities of photodarlingtons are about ten times greater than those of standard phototran- slsiors, but their useful max- imum operating frequencies are only tens of kiloherU. Preamplifier circuits Photodiodes and phototran- slstors are used as lightwave signal receivers or detectors in fiberoptic transmission lines. The light traveling in the optical fiber can be modulated by either analog or digital methods. Pho- todiodes and phototransistors are also detectors in op- tocouplers and infrared light- beam Interruption switching and alarm-control systems. In those applications, the sig- nal reaching the photosensor could either be very strong or very weak. Moreover the pho- tosensor could be subjected to a lot of noise in the form of ran- dom, unwanted visible or in- frared emissions. To minimize interference problems, optical links are usually operated in the infrared range* and the op- tosensors output is then pro* cessed with a low-noise pre- amplifier having a wide d>'Tiam- ic operating range. Figures 28 and 29 illustrate typical exam- ples of preamplifier circuits with photodiode sensors. The Fig. 28 circuit is de- signed for use with a 30-kilo- hertz carrier The tuned circuit, consisting of LL CI. and C2, is wired in series with Dl and damped by Rl to provide the necessary frequency-selective low- noise response. The output signals are tapped off at the junction between CI and C2 and then amplified by Ql, The 20~kilohertz selective preamplifier shown in Fig. 29 is intended for an infrared light- beam alarm. The alarm sounds when the beam is broken. IWo IR photodiodes. Dl and D2, are wired in parallel so that the op- tical signals are lost only when both photodiode signals are cut off. Register Rl is shunted by 01 to reject unwanted high-fre- quency signals. The output sig- nals across Rl are fed to the inverting op-amp through C2» which rejects unwanted low-fre- quency signals, R-E BATTERY TESTER continued from page 62 base terminals of a standard #1157 automotive incandes- cent lamp and crimping al- ligator clips to the other ends of the wires. This load can then be clipped across the batterys ter- minals for several hours. (The assembly is also a handy inex- pensive trouble-shooting light that you can use for working under the hood of your car} After disconnecting the load, wait until the voltage stabilizes before doing the CCA test. Ide- ally, the open, circuit voltage of a new battery should be 12.6 volts (±0.02 volt). GRAB test procedure When using CRAE to test a battery follow these steps: L Determine the manufac- turer's CCA rating for the bat- tery. This information Is a reference that will help you to determine if the battery should be replaced. Also, estimate the ambient temperature of the bat- tery by taking the air tempera- ture of the batterys location Immediately before you begin the test, 2. Disconnect the ground cable from the battery if It is con- nected to the electrical system of a vehicle before doing the test. 3. Using an accurate digital multimeter with a basic DC- voltage accuracy of at least 0,5%. measure the open-circuit voltage of the battery If the volt- age Is below 12.25 volts, re- charge the battery and recheck the voltage, 4. Under some conditions the battery voltage will exceed 12.65 volts. In that case, discharge it slightly as explained earlier in the text. Because CRAE itself is a light (2.5 ampere) load, it can be used to discharge the batter>'. However, Do not use CRAE for sustained periods of more than two minutes because it is not designed for continuous use f To measure the output of the battery most accurately, the bat- tcry s open-circuit voltage should be between 12,4 and 12.6 volts. 5. Connect CRAEs positive (red) alligator clip to the " + " ter- minal of the battery and the negative (black] clip to the terminal. Adjust the MAxaNFiADJ knob on the panel so that the needle points to the maximum deflection. Be sure that all con- nections are secure. A poor al- ligator clip connection will cause CRAE to give an er- roneous reading. 6. Throw switch SI to the timer RESET {left) position and then let it snap back to the center "off* position. Remember that SI has three positions: center is "off* and the others are momentary action. 7. lb test the battery, hold SI in the TEST position until the LED lights in about 1 minute. When that occurs, take the reading and let 81 return to the center "off' position. 8. For the most accurate retest the battery. Any difference be- tween the first and second read- ings on a satisfactory batteiy is insignificant. However expect that the second reading on a weak battery will be lower than the first. The second reading is the most accurate. If you want to retest the battery a third time, be sure to wait at least two minutes between the tests to avoid stressing CRAE, 9. Do not use the maxunfiadj knob for the second or subse- quent readings on the same bat- tery: (The 1-minute, 2.5-ampere load of the initial test has changed the battery*s open-cir- cuit voltage.) However, if you want to test another battery pro- ceed as stated originally Also, if the subsequent test on the same battery occurs an hour or more later, reset the meter nee- dle to the INF position. A general rule is that If the open -circuit voltage voltage of the battery is ^ constant^ — no matter when test- ed — use the max tiNFi adj knob g to set the meter needle to the inf position. ? After determining the crank- g ing amp capacity and tempera- 3. ture, use either the GW BASIC ^ program In T^ble 1 or the graph | in Fig.l to determine the bat- tery *s CCA capacity. Replace the battery if the calculated CCA is substantially lower than the wanufacturerk rating, R-E 71 ASK R E continued from page 10 screen and where to turn it off on the left, you can see why there s no room for more than one set of con- trol signals — no matter how many images you want to mix together There are two standard ways to mix video signals. The first is to sep- arate the picture and conlnol infer- mation from each signal and then to HARD-DRIVE LED I have an AT-class computer with an IDE hard drive and I just recently added a second hard drive. The equipment works fine, but the LED that indicates hard-drive activity lights only when the firs! drive is active. The second d ri ve works fine, but the LED doesn t come on. Can you tell me what's wrong? — G. Fishben, Enterprise, NY Since both hard drives hhr work- and other lines, The real answer to your question can be found by look- ing at the pinout of the standard IDE connector If you're lucky, that can be found in the instruction manual you got with the controller card. You'll see that pin 39 is marked as "SLV ACT" — ^which. in plain Eng- lish, means "slave drive active/" That line goes low when your sec- ond dnve is selected, and it should be connected to the hard-drive ac- tivity LED along with whatever other 0^^ U/^^ OF NTSC STASm^D COi.€>/i i^/l>BO' FtG . 3— TO MIX TWO OR MORE VIDEO SIGNALS you must combine the picture areas, but use only a single control area. combine them with a single set of control information frt>m one of the video sources. The second method is similar but instead of using the control information from one of the original sources, you generate it separately. Remember that the picture infor- mation in each Itne has a start and end point. Before you mix the pic- tures together, you have to be sure that all of them are lined up accu- rately. The circuit that does every- thing necessary to mix video signals IS calfed a timebase corrector. It's a fairly complex piece of equipment and, as you might expect, it cames a fairly serious price tag as well. Nothing would make me happier than being able to give you a simple circuit to do the job but. unfor- tunately. I can't, I can tell you. how- ever that it s worth your time to try to come up with one becausen if you're successful you'll have something that can lead to a lot of pnDfit and an early retirement. ing correctly. I have to assume that the question is academic — interest- ing, but not vital. The LED activity indicator is a nice thing to have, but we'll both agree that it's a lot better to have the drive working and the LED messed up than having it the other way around. The reason for the problem is not with the drive but with the IDE con- troller card. The people who made the card in your computer or the circuitry on the motherboard if your computer has a built-in IDE control- ler, cheaped-out when they de- signed the circuit. For some reason, the IDE standard isn't quite as "standard" as some of the eariier hard'disk encoding schemes such as MFM. RLL or even SCSI The hard-disk activity LED is usu- ally triggered by decoding several of the control lines connected to the cable. The exact method varies from card manufacturer to card manufacturer, but it's generally some combination of read, write, control lines are used for the first drive. If you put a meter on that pin and access yoursecond drive, you1l see that the pin becomes active. The manufacturer should have used an OR gate Cor a reststor-combina- tion equivalent) when the card was designed. You can do it yourself by tying pin 39 to the LED connector with a resistor of about 1000 ohms. One side of the LED is connected to 5 volts and the other can be the output of a gate or a node on a resistor network. You want to con- nect the 1K resistor from pin 39 of the IDE connector to the pin of the LED that's not connected to 5 volts. Since you probably don't have sche- matics for the controller card, it s a good idea to use a small diode such as a 1 N91 4 to isolate pin 39 from the LED. Since you have to take your computer apart to do that, you have to figure out if the final result is worth the effort. Should you decide to do it. you might consider using a second LED (triggered by pin 39) as an indication that the second drive is active. R^E WARC '92 continued from page 40 WARC-92*s notable statistics WARC -92 was attended by more than 1400 delegates from 127 countries, and there were several hundred obsei-vers from 31 regional and international organizations- The conference produced six million pages of text weighing 28 tons. There were two all-night sessions on the last two days of the con- ference» and when ihe con- ference concluded, most of the participants weren't clear about what decisions had been made, particularly in the sound- broadcasting satellite senice, BSS. A total of 81 declarations were made at the end of the con- ference. A declaration is a state- ment by a countrys delegation that is appended to the Final Acts of the Conference, calling attention to an issue of par- ticular concern to that delega- tion. Perhaps the most telling declaration was entered by the French Delegation; it set the tone for the conclusion of WARC-92. It expressed reserva* tions about the number and complexity of the texts adopted within the short time of WARC-92, and it was concerned about possible interpretations which would not conform with the final consensus of the con- ference. [Editor's Note: Stanley Lcinwoll. director of engineering in U.S. for RFE/RL, was a member of the United States Delegation to WARC-92J R-E LETTERS continued from page 15 nine beast whose barking can be- come quite a nuisance. About a year ago t built a magnet- ic field meter that was featured as a kit in Radio-Electronics After completing the unit. I was checking around the house for relatively high sources of EMFs when I noticed that my dog. Sparky, had a very in- tense field surrounding him. I initially thought that was due to a high static charge accumulated from rolling around on the carpet or brushing against the TV screen. I tried dis- charging him to a water pipe and even rubbing him on the carpet, with no measurable effect on the field. Sparky is a very large dog and somewhat hyperactive. I believe that might coincide with his high electrical potential My concerns are with the micro- receiver- resonator module. That is obviously a very low power unit using the dog's own bio-magnettc field as a power source. I am afraid that Sparky s unusually strong mag- netic field could quite possibly inter- fere with, or completely inhibit, the operation of this unit. With it s cost in mind. I would hate to think that it could be damaged or even rendered useless after it's installed. I am hop- ing that you can provide me with a source for detailed specifications concerning power requirements and EMF shielding of this unit. If everything works out okay. Tm planning to use multiple resonators at various locations on Sparky in combination with an extensive train- ing program in hopes of teaching him some very advanced tricks. That might also prove to be the long- awaited edge we need to take the blue ribbon at this summers dog show. Although this might sound far- fetched, I'm even thinking of adding a module to my home-automation system that would allow complete control over Sparky s behavior Thanks for your continued efforts in bringing the latest In innovative, entertaining, and exciting proj- ects — and your best April Fool's kit yet! JOHN SU\DE Hillsdafe, Ml Kudos to the author of "Remote Control For Your Dog*" (Radio- Electronics, April 1992). The best April Fool's article yet. Incidentally, for (hose readers who might be hav- ing trouble with the high price of the actuator module, I went to work right away in nny basement. Tm proud to say that I can make avail- able the same at a price of $4,95 per unit. BYRON HODGES Thank you for the article "Remote Control for Your Dog." It is yet an- other star in Radio-Electronics glittering firmament. However, it seems that Mr Canino failed to real- ize the true potential of his device. The applications need not stop at simple behavior suppression. A dog is an intelligent animal and can be taught very complex behaviors. Why not use the subcutaneous re- ceiver to initiate a behavior, for in- stance, fetching your slippers. Why stop there? Several receivers could be implanted in different locations and their control could be consoli- dated in one transmitter A buzz in the left thigh would make the dog lick-shine your boots, a tickle be- hind the left ear to answer the door, and a tingle in the tail to fetch you a beer from the fridge — all for the fraction of what it would cost for a butier or personal robot. I personally have trained my dog so that at the receipt of my sum- mons he leaps onto a treadmill that provides electrical power for the "Low-Cost Laser Printer" that I built from an article in last year's April issue, Mr Canino failed to address the potential for abuse of this tech- nology For example, what if your dog was kidnapped by a hostile in- telligence agency or an estranged family member who subjected him. unbeknownst to you, to a receiver implant and intensive aversion therap/. He returns seemingly un- harmed, but ready at any moment to receive the tear-yourthroat-out sig- nal from a waiting agent. The last place the secret service would look for a threat to the President would be his dog! I have obtained evidence that this may already be happening to the pets of many high-ranking officials. The implant is small enough to use in all sorts of animals— cats, par- rots, tions. tigers, bears, and even farm animals are no longer above suspicion. This may very well create a totally new arena for military esca- lation among the major world powers. I. for one, will never look at my pet turtle in quite the same way ever again. JAMES SENTMAN Lake Bluff. IL Electronics Paperback Books GREAT PAPERBACKS AT SPECIAL PRICES n Bf»248— TEST EQUIPMENT CON- STRUCTION $S.9S. Details con^ slruclcn of simple, in- expenslwo, but ©x- trdmoly useluJ tesi aqutpmi^nL AF Gen, Test Bench Ampl. Av- cJioMilliTOftmeter, Iran- sislof Tester and si)( tnoro, n CM0S1— CMOS POCKET GUIDE 1 tie.95. Works tike tho TTL Guides but cewfS all Hjfnmonty used CMOS standard devices. Six maior sections. The lirst shoiws Ihe device schematic:. Nexl is a brief descrlptbri of the c&mpoFtont and 1$ bilowed by futi^ operaUng deiaiis. Tl^e fourth secttcw^ lists major appltca- lions, while \h@ Sih and 6lii sections present essentia] data tor ihal device and a Jist of the f&ievent manufaclunara. Tlie final tw sections are a valuablo CTOSs-reference. 1 1 ! 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O SPi&S— INTROOUCTION TO SATE LUTE TV,,.., $9.95. A definmvfl introdudjonto (he Sutjed wnttAn tof the profession^ eogan*er, etoctronics snrhusiast. (Jr others wtio want to know more belbro ihey buy, S ^ lO in. D »P1 90— ADVANCED ELECTRONIC SECURITY PROJECTS S5.95. Ii>dudes a passive infra-FOd dotactor, a fiber-opik: kxjp alaim. computez-lMSdd iklianTts and an unt^ual lomi ot uttrasonk: ir^trndef detector. □ eP235— POWER SELECTOR GUIDE.....$TO.OO. Complete guide lo semtconduc- tor power devices. More than IDOO pow«r handling dijvice^s are rncluded. They are tabulated m alpha- numenc sequency. by technical specs. Includes powe* dwxtes. Thynstofs. Tnacs. Po*of Trarwsiofs and FET's. n epa34— TRANSISTOR SELECTOR GUIDE... ..$10.00. Companion volume to BP?3&. &ook covers more tKan UOO JEDEC, JtS, and brand-specific devices. Also contains tisling by case lype. and electi:onic parameters. 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[ i BP122— AUDIO AMPLIFIER COHSTRUCTIOH t5 J5, Construction details for preamps and power amplifiers up through a IQO^watl CX^-coupled FED amptrliier. n BI>92-CR¥STAL SET CONSTRUCTION,..-.^^, EyCf¥th*ng you need lo krxiw at>Oul buikJing crystal rad«) receivers. ! J 0P4S-PROJECTS IN QfnOELECTHONICS,....$5.50. fndudes ihfrB-nKi detec- tors, transmitlers, modutated light Transmission arxl [phonographic applicattons. i BPaSS-INTERNATlONAL RAD^O STATIONS GUIDE $7.95. Provides the casual li stoned, amateur radio DXer and the professional radk) monitor with an essential reference work designed to guide him or her around than ever more complex radio bands. ELECTRONIC TECHNOLOGY TODAY INC. PO. Box 240. Massapequa Partt, NY 11762-0240 Name Atjdress . City SHJFPING CHARGES IN USAAHD CANADA S0.01 to S5.00 S5.01 tDSIO.OO S2.50 -Slate . RE792 SiO.Oi to 20.00. .. S20 01 to 30 .00 130.01 to 40.00 .. S40,01 to 50.00 ,. 550.01 and above . .S3,50 .S4.50 .S5.50 .S6.50 .S8.00 SORRY Mo orders accepteij oytside of USA & Canada Total price of merchandise . Shipping (see chart) Subtotal Sates Tax (NYS only) , Total Enclosed Number of books ordered CH All payments must be in U.S. imds HARDWARE HACKER Dye-based solar energy, Neo-Geo interface cables, another sad patent story, micro-avionics newsletter, and RGB monitor fundamentals. DON LANCASTER Uh whoops. Back in April (page 65. Fig. 2). one of my last minute "improve- ments" to the PC layout for the sync stripper and universal video inter- face left one extra trace from pin 9 to the SYNC output tine. Sorry about that, if you have already etched your board, just cut that tmy run out. Fig- ure 1 had it cormct. Moral: It is always the things that you thought you triple checked that are certain to return to haunt you. We will see several other possi- ble changes to the sync stripper in just a moment when we look at some new Neo-Geo interface ideas below. An update to the crystal-sta- bilized FM stereo broadcaster cir- cuit that we looked at last months Tve now had a brief chance to check into that new Sony XA7A unit. While it uses pretty much the same circuit we looked at, it seenris more costly kJutzter. and far harder to hack. The BA1404 has a surface mount package. Them are some tight and tiny shields^ and some awkward "3- D'* component arrangements. Sony appears to be getting two channels by pulling its crystal an as- tounding 200 kilohertz in either di- rection. I'd bet its stability isn't as good as in a Pioneer CD-FM-I. Speaking of which, it should be possible to significantly improve the CD-FM-ls range by replacing the SAW filter load used by Q4 v/ilh a simple tapped resonant tank lo- cated outside of the existing shield. That would switch Q4 from class-A over to class-C operation. Some by- passing on R19 could also help, as might lowering its value somewhat. Mora details when I get a chance. Meanwhile, do let me know what you come up with on your own. Patents again The morning mail had yet another sad example of a hardware hacker done in by the patent system. Or more conectty, done in by the out- landish popular myths and all the gross misconceptions surrounding patenting. One more time: Any hardvvBre hacker-based small-scale involvement in the patent system is absolutely certain to result in the net loss of time, energy money, and sanity Your state lottery is a vastfy better Investment. This example involved an Oregon inventor who sent me a copy of his new patent and asked for my help in marketing it. The patent is intended to recover electrical energy from a steam line by impinging the steam onto a piezoelectric generator The patentee admitted he lived in a very "remote area" where all research was difficult. And he did specifically ask me for comments, so here goes. Well it must have been my kind of remote area. There was obviously no telephone available to call the Dialog Information Service, and no postal or UPS service to receive l/M/ reprints. Their local library had to be so small that they had no Uhlrichts Periodicals Dictionary which included the EPRl Electric Power Research Institute Joumai And. of course, no Encyclopedia of Associations which would in- clude the Association of Energy En- gineers with their great conference publications on this type of cogeneration device. I felt the patent was rather weak. I NEED HELP? Phone or write your Hardware Hacker questions directly to: Don Lancaster Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 think I could personally find all kinds of prior art way back in the 1890-1930 time frame. And f do think the idea would be so totally obvious to any "practitioner in the field" that prior art would not even be required to quickly bust this pat- ent. In fact, attempting to defend it could easily lead to a nasty old frivo- lous litigation countersuit. "Outside of that Missus Lincoln, how was the play?" Well. I do not know of any high-power electricity* producing piezo generators. Piezo tends to be grossly inefficient and involves frequencies and imped- ance levels that ane hard to ele- gantly deal with at higher power Piezo transducers tend to have lousy power factors, since they are often very capacitive. The optimum working temperatures are well be- low that of Ir^ steam. Further, we obviously have a heat engine here that has to obey the laws of thermodynamics. The best possible efficiency (called the Camot efficiency) would be rather low. Which is why we don't have too many steam engines these days. And I feel the P-V Cpnessure-volume) diagram for the proposed impinge- ment system would be absurdly far away from the best possible. It is cleariy not adiabatic. I would be quite surprised if the overall electrical recovery efficiency could ever exceed 0.1 percent. Thus. 1 feel this pfDduct would never be able to pay for itself or for the ^ time value of the money used. Let ^ alone recover any useful power. fg So, Td guess my answer on any m marketing of this product would be a "Uh, to whom?" I Now, there are all sorts of exciting 8 steam recovery developments go- ? ing on. They involve bottoming and scavenging cycles and can use ex- otic fluids other than water vapor And th^ are revolutionizing com- mercial electric-power production 75 by sharply rmproving efficiencies. And the pulse-combustion furnace folks are playing lots of neat games in super efficient latent heat (gas to liquid) recovery. So there are bunches of new possible oppor- tunities m this area. Some of them eminently hackable. By the way. one ancient but quite readable book on thermodynamics Is Sanford's Heat Engines, found in the Doubleday Science Series^ No hacker can afford to ignore the fun- dannental laws of thermodynamics. Where to go from here? First and foremost, avoid any and all involve- ments with the patent system in any way shape, or form. Do so re- ligiously. Second, getyourself a fresh copy of 7?ie Case Against Patents, either in my Blatant Opportunist reprints or as our GEnie tutorial PSRT text- file #162 NOPATENTTXT. Rumor has it that this repnnt may also shortly appear in the Whole Earth Review. Third, there is a unique magazine known as Midnight Engineering that NEW FROM DON LANCASTER HARDWARE HACKER STUFF HardwatQ Hackor Raprlnta II or III 24.50 Midnight gngln^arlng Reprlnia I n credl b ie Sec rot M o ney Mac h\m 1 8 J 0 CMOS Copkbook 24.50 TIL Cookbook 24.50 Active Filter Cookbook 19,50 Micro Cooktiook vol I or II X9.5Q Lancastor Classics Library 100.50 Appt^Wrltor Cookbook 10.50 POSTSCRIPT STUFF A»k The Guru Repdnls II or Itl 24.50 LaserWriter Secret^ [lla/Mao/PC) 29.50 FostScrJpl Show fi Tell 39.50 Intro to PostScript VHS Vtdeo 39.50 PostScript Bf^glnner Stuff 39.50 PostSc rtpt Cookbook (Adobe) 1 6^50 PostScript Rer Manual II (Adot>e) 25.50 PostScript Program Design (Adobe) 22.50 T^pe 1 Font Format (Adobe) 15.50 LaserWrit&f Reference (Apple) t9.50 Real World Poetacrlpt (Roth) 22.50 Po^tSof [pt Visual Approach (Smith) 22.SD Thmking in PostScript (l?eld) 22.50 Undsl PS Pgr mmg (Holtzgang) £6.50 Th 0 Who le Wo rks ( a 1 1 Po s IS crip t} 3 4§. 50 BOOK-ON-DEMANO STUFF Book-on-demand resource kit 39-50 GEr^le PSRT sampler (ile/Mac/PC) 39.50 FREE VOICE HELPLINE VISA/WC SYNERGETICS Box 809-RE Thatcher, AZ S5562 (602) 428-4073 CIRCLE 219 OH Ffl EE INFORMATION CARD jELEtTRONIC SURPLUS RESOURCES AU Etectronics Corp, PO Box 567 Van Nuys, CA 91408 (000) 826-5432 CIRCLE 301 ON FREE tNFORMATlOW CARD American Science & Surpius 601 linden Place Evanston, IL 60202 (708) 475-8440 CiRCLE 3QZ ON FREE INFORMATION CARD C & H Sales PO Box 5356 Pasadena, CA 91117 (800) 325-9465 CmCLE 3D3 ON FREE INFORMATION CARD Circuit Specialists PO Box 3047 Scottsdale, AZ 85271 (800) 528-1417 CIRCLE 304 ON FREE INFORMATION CARD Fair Badio Sales PO Box 1105 Lima. OH 45802 (419) 227^6573 CIRCLE 305 ON FREE iNFOflMAtlON CARD Herbach and Rademan 18 Ganai Street Bristol, PA 19007 (215) 788-5583 □RCLE 30§ ON FREE INFORMATION CARD Martin P. Jones & Assoc. PO Box 12685 Lake Park, FL 33403 (407) 848^8236 CtRCLE 307 ON FREE INFORMATION CARD Archie McPhee PO Box 30852 Seallfe, WA 98103 (206) 547-2467 CIRCLE 30a ON FREE INFORMATION CARD R&D Electronics 1224 Prospect Avenue Cleveland, OH 44115 (216) 621-1121 CIRCLE 30§ ON FREE INFORMATION CARD Surplus Center PO Box 82209 Lincoln, NE 68501 (800) 488-3407 CIRCLE 310 ON FREE INFORMATION CARD Surplus Traders PO Box 276 Alburg,VT 05440 (514) 739-9328 CIRCLE 311 ON FREE INFORMATION CARD Specifically supports the small- scale developers, product pro- totypers. and startups. With proven and realistic help. Free samples on request. Inventing, of course, is a highly reprehensible and incurably addic- tive social disease that is simply not talked about in polite company. So, fourth and finally, you might want to join Sonne AA-type support group. A typical example group would be the Zimmer Foundation, associated with the Michigan inventor's Coun- cil. Just be certain that your se- lected group \sn{ a marketing scam in disguise. Another solar breakthrough? Lots of credibility has been newly given to dye methods of solar ener- gy conversion. As we have seen in past issues, certain dye molecules can act as both an antenna and nec- tifier, converting any incoming pho- tons into an electron current. The dye method is potentially very cheap, very efficient, and should end up quite easy to mass-produce. Only tow-cost and low tech materi- als are involved. Do check out the October 24, 1991 issue of Nature (vol. 353 #6346). Especially Thomas Mal- louks Bettering Nature's Solar Cells Con pages 698-699) and also Brian O'Regan and Michael Gratzels A Low-Cost High-Efficien- cy Solar Ceil Based Upon Dye-Sen- sitized Collodial Titanium Dioxide Films Con pages 737-739). Some librarians appear to have lots of trouble finding Nature, possi- bly because it is British, Which is a real mystery, since Nature is re- garded by most of those in the know as the finest and most significant science publications anywhere in the world. Obviously, any magazine that gets up to weekly issue #6346 must be doing something right. If you get any static picking up any Nature copies locally scream and holler and stamp your feet. Or use the address found in our Names & Numbers sidebar Figure 1 shows you the general idea behind any dye-based solar cell. The cell uses liquids and is re- lated to a wet-cell battery. An elec- 1(H1-3()()MH/ Modulars Willi A I'Uturc Incoming solar energy O Transparent glass cover Transparent concfuclor Dye rnolecLile monoEayer A thin but very rough semiconducting layer of titanium dioxfde Bottom conductor Lithiiinn hydroxide or other electrolyte sotution {+) ^■fl^ ^^'^ ? *^ Power load Fia 1— ANOTHER SOLAR BREAKTHROUGH? The dye-based solar method uses a large-area monolayer of individual dye molecules to act as opttcal antennas and rectifiers. An electron "borrowed" f rom the electrolyte by the dye gets its energy level raised by an mcoming photon^ jumps the rectifying semtconductor gap, delivers useful load power, and then returns to the electrolyte. The high-efficiency process is related to the first stage of plant photosynthesis. Alt the materials used are cheap and fairly Jow tech. tfolyie of a lithium salt or something similar is used. The uppermost ter- minal is a conductive metal film un- der a layer of clear glass. The bottom terminal is also a conductive metal film. Onto this film, a very thin and very rough layer of a titanium dioxide semiconductor is deposit- ed. Together they form the metal barrier diode. The semtconductor film is made as HDugh as possible to greatly in- crease its surface area. The present effective areas are in the 2000:1 range. A one-molecule thin monofayer of trimetric ruthenium dye then is deposited on the semi- conductor surface. The single-dye molecules can act as both an antenna and a rectffier. An existing electron in the elec- trolyte solution will have its energy level increased by the incoming op- tical photons. These high-energy electrons jump the semiconductor junction, go through the load deliver- ing useful power, and return via the top electrode, creating a self-rectify- ing and light-induced photocurrent. So far, the actual efficiencies are only slightly better than polystlicon cells. But all of the materials are far cheaper Ctitanium dioxide is used to make while house paint; only small amounts of dye are used). They also lend themselves to larger area, high-volume processing. There are several remarkable sim- ilartties between dye-based solar and plant photosynthesis. In fact, the biggest difference is that dye- based photosynthesis stops with its generated electrons, while plant photosynthesis will go on and use the high-energy electrons to drive the intermediate chemical re ac- tions ^ which can ultimately create sugars, cellulose, and other tasty stuff. Dye-based solar*energy con- version is already more efficient than the most efficient plants known today On the other hand, plants can create and repair themselves. RGB video fundamentals I have recently been working with Dennis Carper of Redmond Cable in interfacing all sorts of video games to all types of leftover sun plus computer monitors. So, I guess it might be a good time to review some of the fundamentals of RGB monitors. The reasons we go to the sepa- rate red-green-blue route in the first place are for picture quality and for picture resolution. Regardless of how much trouble you go to. it is simply not possible to gtomp onto the antenna terminals of an ordinary TV set and display anything even renjotely near what is needed as a bare minimum for all of today's color Square ' Waves, Ail- Around Value. Choosing reliiibit;, long-iisiing ascillostopt prohes is no longer a prtrfjIeoL Select from 10 modular kits with interchEmgeable lips and inieiface ct^nneaioas: mm Suindard lOOMHz to the Profejisionai 200-300.ViH?, including an RF Deteaor prol^e kil Perfonmncc? YoulxiXl XlO ancf switchal)le attenuatioas with 1- l6ns rise tinies and 6-60pF input irtijiedi nces to nmch up with your^ mast demanding uses, h And, readily replaee-al^le parts will assure long senice life. They're av^iilable now ' You'll get square waves We're iMaking Technology Easier To Live With. I with vour Cat! F.\X CT %vnir tcxLiy lor xtmv frw Ektimnk Test Avc&/nnies CalaA^ ITT Pomona 11ic\V<)rld kiidtT In Test AacJisorius 1500 E. Nin!h Su^e). P.O. Box 2767 Pomona, CA91769. {7H^ 469-2900 FAX (714) 62&^33U, 1 m 3 77 CIRCLE 101 OH FREE INF ORMATtON CARD computer displays or pnemium ar< cade video games. The needed bandwldths and scan rates are sim- ply not there. Unlike broadcast signals (such as NTSC. PAL or SECAM). there are no universal standards being used for RGB monitors. If it has three separate video lines on it, it is an RGB system. Fferiod. Thus, you will have to be very careful about what your video source and your video monitor are capable of before you try to connect them. The simplest RGB system uses "TTL" monitors. It does not accept video as such. Instead, it receives digitaf logic signals that tum its red, green, and blue beams entirely off or on. Thus you can get only eight possible colors. All eight of which are always Fully saturated. Some TTL monitors include a fourth bfightrress line that gives you a choice of "full" or "half"" bright, in- creasing the apparent color total to sixteen. Instead, on a //near RGB monitor, all shades of all colors are possible. Linear monitors need much more in the areas of video amplification and linearization (or gamma correction) circuits. Obviously, linear monitors are required for "real" video from a cable or broadcast source, or when- ever yoi#eed a very wide range of hue and saturation values. Most linear monitors are not too fussy over accepting interlaced scans » used on standard TV, or the noninterlaced scans, as must be used on most data displays. But linear monitors are extremely fussy about their horizontal scan rates. Ordinary TV uses the hori- zontal scan rate of 15,735 kilohertz for color or 15.750 kilohertz for black and white. Most computer scan rates are double that, up in the 32 -kilohertz range. And premium systems can have scan rates of 80 kilohertz or higher Unless your monitor is carefully designed to be a multisyncing type, it will accept only a ^ry limited hori- zontal scan rate range. Thus, there is no vvayyou could use an ordinary bruadcasl RGB monitor to display a Mac or VGA output. It flat out can not operate at the higher scan rates. One of the ruder surprises to Ap- ple llgs people downgrading to a Mac LC is that their old color monitor will no longer work. Their llgs monitor is a tsroadcast'Only style, while those LC video scan rates are up in the 30* kilohertz range. Fortunately a simple jumper- ing option (which we saw a few col- umns back) lets the LC use an ordinary and cheaper VGA monitor Thus* you have to be sure that your intended RGB monitor is capa- ble of accepting the horizontal scan rates provided by your video source. Some combinations simply will not work. A ftna! major consideration is the Ashtech 1170 KiJerRoad Sunnyvale, CA 94086 (408) 524-1400 CtRCtE 312 ON FREE INFORMATION GARO Dialog 3460 Hillview Avenue Ralo Alto. CA 94304 (415) 858-2700 CIRCLE 313 ON FREE INFORMATION CARD GEnie 401 North Washington Street Rockville, MO 20850 (800) 638-9636 CIRCLE 314 ON FREE INFORMATION CARD KepfO 630 Axmintster Drive Fenton, MO 63026 (800) 325-3878 CfRCLE 315 ON FREE INFORMATION CARO Lighting Dimensions 135 Fifth Avenue New York, NY 10010 (212) 677*5997 CIRCLE 316 ON FREE INFORMATION CARD Maxtm 120 San Gabriel Drive Sunnyvale, CA 94086 (408) 737 7600 CIRCLE 3ir ON FREE INFORMATION CARO Micro-Aylontcs Newsletter 42418 Valley Road Drexel Hill. PA 19026 (215) 259-6430 CIRCLE 31 S ON FREE INFORMATION CARD Midnight Engineering 111 E Drake Road Ste 7041 Ft Collins, CO 80525 (303) 491-9092 CIRCLE 319 ON FREE rNFORMATTON CARD monitor's resolution. The fBSolution is set by the video bandwidth and the pitch of the color bars or dots on the screen . Images will smear if you try to view them on any monitor whose resolution is too low for the intended application. The results can end up as a cause for slight eyestrain to being totally unviewa- ble. So, a second rule: Make abso- futely certain that you test and use any monitor for its intended pur- pose before you actually pay for it. Your video lines could be high im- pedance cables if the runs are shortn or terminated ones (usually Nature ^^^I^^^H 65 eieecker Street ^^^H New York, NY 10012 (212) 477-9628 CIRCLE 320 ON FREE INFORMATfON CARD OKI Semiconductor 785 North Mary Avenue Sunnyvale. CA 94086 (408) 720-1900 CIRCLE 321 ON FREE INFORWATION CARD Redmond Cable 17371-A1 NE 67th Court ^ Redmond. WA 98052 m (206) 882-2009 CIRCLE 322 ON FREE INFORMATION CARP Society Optical Engineering PO Box 10 Betlingham, WA 98227 (206) 676-3290 CIRCLE 323 ON FREE INFORMATION CARO Techniks, Inc 45 J. Ringo Road Ringoes, NJ 08551 CIRCLE 324 ON FREE INFORMATION CARD UMI 300 North Zeeb Road Ann Arbor. Ml 48106 (800) 521-3044 CIRCLE 3:K oh free INFORMATION CARO Whole Earth Review 27 Gate Five Road Sausalito, CA 94965 (415) 332^1716 CtRCLE 326 ON FREE INFORMATION CARD Zimmer Foundation 1683 Plymouth Road Ann Arbor, Ml 48105 (313) 663-8000 CmCLE 327 ON FREE mFORMATlON CARD 0.1 pF Weak or linear cofnposite sync input I — V\^— * 470K 0.1 pF SYNC out (nomial) JUL o SYNC out (rare) I FiG. a— THIS SYNC AMPLIFIER can take "'linear" or "weak" RGB composite sync signals and make them CMOS- and/or TTL*compallble. It also gtves you an optional and rarely needed active-high sync output. 75 ohms) for longer distances, A fair amount of power is required to properly drive a terminated video cable. Maxim is one good source for video drivers. Video cables are best made either as fuWy shielded, or. at the least, as twisted pairs. If any separate gnDunds are provided, they should be used as th^ were intended. If your video source has any DC offset present (such as the emitter* follower outputs of a Super Ninten- do), then you must provide for a capacitor coupling between the source and the monitor Very large capacitors are recommended, at least 220 microfarads or more. But they might already be built in, so check first. There are several synchronizing options used in RGB systems. Some systems tack sync signals onto the green channel and later strip them off. But most systems have separate sync lineCs) that de- liver horizontal, vertical, or com- posite sync signals. To further confuse matters, sync lines can be smaller one-volt signals at analog levels, or they can be TTL- or CMOS-compatible. Others can be at TIL levels, but end up too small for CMOS and too weak for TTL. We saw a Super Nintendo workaround for this last month with a simple 680-ohm resistor to ground. Typical sync lines are active-low, meaning that the sync tSps are at ground. But a few Cespeclally earlier Commodore products) demand an active-high composite sync. Figure 2 shows you how to use several inverters to amplify low-level sync signals into full CMOS and TTL compatibility giving you a choice of either active- low or active- high sync tips. The first stage can be a biased inverter amplifier having a gain of twenty or more. The sec* ond inverter further cleans up the nov/-digital waveform, while the third and fourth stages act as inver- ters or drivers. If you try that linear amplifier stunt with other CMOS gates or inver* ters. be sure to use "single stage" unbuffered CUB) versions: other buffered ones might have too much gain and could osciflate. More de- tails in my CMOS Cookbook. Our sync separator and universal video interface from the April col- umn is easily modified to provide suitable sync amplification for the Neo-Geo or Super Nintendo. Sound is dealt with separately in an RGB system. Sometimes, there will be no sound at all. One clue here is the absence of any volume con- trol. Radfo Shack makes a neat little $1! lab amplifier that can sit in for you. Other options are monophonic sound, stereo sound, or a multiplexed stereo sound accepting R + L and R - L inputs. Super Nin- tendo uses a multiplexed sound output. If you forget to demultiplex, one channel will sound monophonic. and the other might sound awfully Earn Your B.S. Degree in ELECTRONICS or COMPUTERS By Studying at Home Grantham College of Engineering, now in our 42nd year, is highly ex- perienced in **distance educations- teaching by correspondence — through primed materials, computer materials, fax^ and phone. No commuting to class. Study at your own pace, while continuing on your present job. Learn from easy-to- understand but complete and thorough lesson materials, with additional help from our instructors. Our Computer B.S. Degree Pro- gram Includes courses in BASIC, PASCAL and C languages — as well as Assembly Language, MS DOS, CADD, Robotics, and much more. Our Electronics B.S. Degree Pro- gram includes courses in Solid-State Circuit Analysis and Design, Control SystemSj Analog/ Digital Communica- tions, Microwave England much more. An important part of being pre- pared to move up is holding the right college degree, and the absolutely neces- sary part is knowing your field. Grantham can help you both ways — to learn more and to earn your degree in the process. Write or phone for our catalog. Toll free, N800-955-2527, or see mailing address below. free t m Accredited b> the Accrediling CominUsion of the NationiJ Home Study Council GRANTHAM College of Engineering Grantham College Road Slidell, LA 70460 a z I 79 8 BLUE VIDEO For linear RGB monitor use, One volt peak-tO'peak gets irttsrnatty capacitor coupled. /RGB SYNC For linear RGB momtof use. Active lowcombinGd vertical and horizonta! sync putses, 1 volt capacitor coupfeci source is not CMOSnTTL compatable and may need amplificalEon, Neo-Geo AV/oui | rear panel female pT\3/ RED ViDEO For linear RGB monitor use. One volt peak'to-peak gets internally capacitor coupted- r- 1 MONO SOUND NTSC VIDEO The monophonlc sound output appears on this pin, One voJt peak is suitable Jor amplifiers but not headphones. Use'separaie shielded cable- Use standard DiN-8 mate connector Platn old NTSC cornposite video appears on this line. The sync tips are at ground. One voR peak to peak into a 750 load. Internally capacitor coupled. GREEN VIDEO A limited amount of >5 votta suppjy powor rr*ay ba drav/n out ot this pin tor sync amplifiers, Limit current to 50 mjJSiamperes and use thorough bypassing. GROUND For linear RGB monilor tise. One volt peak-to-peak gets internally capacitor coupled. Used for all cable shields, video return, and any sync amplifier grounding. FIG, 3— THE NEO^GEO AV-OUT rear connector rias both NTSC and RGB output pins available. Here are the key detalts. tinny and just plain "wrong," To de- multiplex properly, you add the two signals together to get the right channel and subtract them to get the left one. Regardless of your sound sys- tern, totatty shielded audio cables are a must^ Ideally, they should be totally separate from all your video cables, due to the strong *1ium" and "buzz" induced by vertical rate signals. So, what can you interface to what? Use your oscilloscope to view all the normal outputs of your video source run in its intended way. Then do the same for the "normar' inputs to the monitor Some hints: To tell if a source is capacitor-coupfed, briefly connect a 470-ohm resistor between it and ground or +5 volts. If the scope display bounces around and slowly drifts back, you are AC-capacitor coupled. If it stays in the initial posi- tion Cor possibly gets slightly small- er), then you are DC coupled. Be sure to take note any fixed offset voltage. To determine your source imped- ance, note that any resistive load equal to your source impedance will drop your output signal level to one half of the open-circuit value. NeO'Geo interface ideas Sorry, but our renowned experts (the munchkin division of Special Editions) were not at all impressed with the new Neo-Ceo game sys- tem. Their preerence for Super Nin- tendo was totally overwhelming, and I will certainly defer to their ex- pertise. But, if you happen to like the Neo-Geo system. Fig. 3 shows you the rear A/V output interface connector pmouts. There are several interesting In- terface options here. Present are the usual NTSC composite video on pin 3, a ground on pin 2, and a + 5'V0lt supply on pin 4, Vou could use that supply for such low-current needs as modulators or sync ampli- fiers. For RGB use, there is a red line on pin 6. a green line on pin 5, and a blue line on pin 8. Those are capacitor-coupled video with a 70- ohm source impedance. Their RGB active-low sync line appears on pin 7. It is also in the form of capacitor-coupled video at a one-volt amplitude. Thus, the sync line is not presently TTL/CMOS logic compatible, and you might need the sync amplifier of Fig, 2. Figure 4 shows you a baseline RGB interface for the Neo-Geo. The connector is a standard DIN-8 that is Radio Sliack stock. As with our previous Super Nintendo inter- face, stock and custom cables, con- nectors, and any and all individual parts are obtainable through Redmond Cable. Surplus resources As our resource sidebar for this month. I decided I would gather to- gether what I feel are only the best of the very best in hacker surplus stores. These are the ones I have used consistently over the years and can personally recommend. The best surplus store anywhere, of course, is Jerry co, which has re- cently become American Science & Surplus, ft is strong in elec- tromechanical parts and unusual materials. For genuine World War II vintage surplus, Fair Radio Sales is the pre- eminent place to go. For heavier iron stuff, especially motors, step- pers, or hydraulics, try either C&H Sales or Burdens Surplus Center. And for the best prices on a wide variety of components, try Surplus Traders. Several other outfits I have found useful include Herbacti and Rademan (infrared people detec- tors), Marlin Jones (power supplies and steppers), Circuit Specialists (for harder- to- find hacker integrated circuits). Time Line (solid-state imaging chips), and either ^A// £/ec- tnonics or RStD Electronics (gener- ally good electronic buys). Finally, for totally outlandish plain old weird stuff, Archie McPhee is it, claws down. Where else can you get a three-foot rubber iguana? For our contest this month, just tell me about your favorite surplus or any other hacker-friendly and rea- sync amplrffer frorn figure two £ O CO UJ 6 o /SYNC i7j--^\;^-W^A^M^^ (Y) /SYNC GND ©~r — ^^Kz) GREEN (s) — aZZ BLUE ©— ifc: RED (i)— SOUND > < >-0 GREEN D-{?) RED t > AUDIO INPUT FIG. 4— TYPICAL NEO-GEO RGB INTERFACE connections. The details and plnouts vary with your choice of monitor. The sync amplifier shown might or might not be needed. Custom cables and individual parts are available from Redmond Cable, sonably priced source of unusual goodies. There will be several of my Incredible SecfBt Money MBchine U book prizes, plus an all-expense- paid (FOB Thatcher AZ) Unaja quest for two going to the best of all If possible, mclude a catalog or put nne on their mailing list. Be sure to send your written entries directly to me here at Synergetics rather than to Radio-Electrontcs. New tech lit The Ash tech folks now offer some really great and reasonably priced ($100) four-day courses on those GPS navigation systems* be- sides offering free notes. From OKI Semiconductor, some speech application notes on the sol- id-state speech-synthesis chips. The Micro-Avionics Newsletter is a brand new and sonely needed Ja- bor*of-love hacker publication. It focuses on the remote controls, navigation, autopilot mg, and the television links used on low end and amateur radio-controlled R/C mod- els, and other aerial platforms. Sam- ple issues are $5. Another very interesting maga- zine is Lighting Dimensions, a sfick and well-done publication intended for a readership of stage, theater, television, and rock-concert lighting specialists. It s been a while since ! men- tioned the Society for Optical Engi- neering. Their freebie SPIE Tech- nical Publications lists all sorts of unique books and reprints on such goodies as solid-state gyros, high- speed photography, robot vision, lasers, liquid crystals, and even on binary optics. There are several exciting new developments in hacker printed cir- cuits these days. The Kepro folks now offer a new How to make printed circuit boards booklet, A product called PCBTF-1000 is a brand new transfer film for their dr- rect*toner nnethod, newly available by way of Teclmiks Incorporated. And I've just posted my share- ware printed-circuit layout package over to CEnie PSRT as our fife #401 PRNCRCTGPS. Plus our summary tutorial on new hacker printed-cir- cuit techniques as file #419 NUTS3.PS. You will also find lots of wavelet info, caller- ID news, and unique tech tutorials over on PSRT. Your aver- age downloading costs are around 21 cents each. If you are at all interested in the PostScript language. ! stock the blue book tutorial from Adobe; my own LaserWriter Secrets book/disk combo whose insider secrets apply to most printers; and 7jf?e Whole Works, one each of everything worthwhile by all of the major PostScript authors, at an unbeat- able price. As usual, we Ve gathered many of the resources mentioned together into the Names & Numbers or the Surplus Resources sidebars. Be sure to check these out before using our helpline. R-E DIGITAL VIDEO STABILIZER ELIMINATES ALL VIDEO COPYGUARDS While watching rant- al movies, you will notice annoying pe- riodic color darken- ing, color shift, unwanted lines, ffashing or jagged edges. This is caused by the copy protection jamming signals embedded in the video tape, such as Macrovision copy prolectEon, the DIGriAL VIDEO STASI- UZER RX]] COMPLETELY EUMINATES ALL COPY PROTEOnONS AND JAM- MING SIGNALS AND BRINGS YOU CRYSTAL CLEAR PICTURES. 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And since up 1o 9S%o(allVCR and Camcorder malfunctions _ are due to a slmpfe mechanical or ftli>_ctro; mechanic al tslifurB, yoLT nead not spend months or even years of complicated study li>efore starting paidf professional service werfcl Let Vlejo^s Training Program show you how! 1-800-537-0589 or mail coupon to E (Gieck iiippiopnalc box) □ VCR Repair □ Camcorder Repair J Advanced VCK Repair J Fas Machine Repair Name Address C ity/Slate _ mm li Is CIRCLE 111 ON FREE INFORMATION CARD hkviw Kt'ini*U?0 antral 3610 S2e.95 ROBOT BUILDER'^ BONANZA V9 INE\Pl?*StVI a. 37§S 529,95 1^ ind Testing fm Ova Speaker Syslia ELECTHONiCS I 3374 P Softmvtr CourvEs as 2 26e3P Sottco'ifflr 314S S39.9S OSCILLOSCOPE QJBCH'fiqNIC IC CIRCUITS wrm 36^7P $19. as Select any 5 books J°fy \Nher\ you join the Electronics Book Club"*" (values up to $15575) 1938 1«0,0D Micrix«iMputcrs ELECTRONIC POWER SUPPLIES ^. ^9 S27.9S AUDIO EQUIPMENT 2B6TP SI 8.95 Softcovar Troubleshooting & Repairing ± VCRsm ^ SECOND t&nEON ^tF^ 3632 S18.95 3777 S32-95 Counts as 2 As a member of the Eiectronics Book Club » . . . . . you'll enjoy receiving Club bulletins every 3-4 weeks containing exciting offers on the latest books in the field at savings of up to 50% off of regular publishers' prices. If you want the Main Selection do nothirig and it wiil be shipped automatically, ff you want anothef book, or no book at all, simply return the Refrfy Form to us by tfie date specified You'll have at teast 10 days to decide Your only obligation is to pur- chase 3 more books during the next 12 months, after which you may cancel your membership at any tima Afl books ai* 3iat 3f/¥ ) shows how Windows creates a "virtual" PC through the use of several layers of device drives, and (c) shows the Windows NT model, which will bring compatibility with all major UWIK derivatives and mainframe operating systems. for the sake of better performance applications long ago developed the habtt of communicating directly with device drivers, ihe BIOS, and even the hardware foundation. Doing so gained short-term performance benefits, but has created a morass of compatibility issues lhat. to this day, haunt every PC manufacturer, software developer, and end user. For several reasons it would be nice to sever the direct connections between applications and the un- derlying hardware. Doing so would give developers the potential to de- velop device-independent applica- tions that would run on multiple hardware platforms- It would give users a wider variety of choices in making hardware purchase deci- sions. It would give hardware ven- dors freedom to innovate, which wouidn in turn, inspire developers to develop more sophisticated ap- plications. That would, in turn, ulti- mately benefit end users. Enter Windows. And a clever new marketing strategy from the guys in Redmond, Washington. The virtual PC When the industry made the tran- sition from CP/M to DOS. several products allowed users to run CP/ M applications right on their PCs. There were hardware products that amounted to complete CP/M en- gines on expansion cards, emu- lators that created an 8080 processor and the CP/M operating system in software, and (with 8088- compatible V20"s from NEC), emu* lators that ran ihe CPU in an 8080- compatible mode and emulated CP/M under DOS. (In fact some of those software emulators are still available.) As a class, emulators were slow, quirky, and buggy, but they allowed users to run their old software and make a fairly smooth transition to DOS. Running lhat kind of emulator put a "virtual" CP/M machine inside the PC. Ever smce Intel introduced the 386, we've been putting multi- ple 'virtual" DOS sessions on the PC. DESQview and OmniViewdid it for us in a nongraphical environ - ment- Windows 3.0 and higher does it m a graphical environment. So does OS/2 2.0. Windows 3.0 popularized the vir* tual PC with its 386 Enhanced Mode, which does a good job with the video system by emufating text and srmpfe graphics modes. Win- dows 3,1 extends the concept with an optional 32*bit disk, access mode for ST*506-compatible disk controllers. The next version of Win- dows Wfill extend the concept even farther, perhaps to include emula- tion of alt hardware subsystems. (Well come back to that idea in a moment,) OS/2, which has aineady taken the DOS virtualization con- cept further than Windows, also provides the user comprehensive and reliable video and DOS file sys- tem emulation services. Microsoft outlined its vision of the virtual PC, shown in Fig. 1-6, last spring at a conference to inspire hardware vendors to start building multimedia features into the next generation of PCs, Clf all goes well, the fruits of these efforts will start appearing this coming fall) Note in the figure that both DOS and Win- dows applications are completely insulated from the underlying hard- ware. That architecture will make it possible to run identical applica- tions on totally dissimilar CPU s. Mi- crosoft s initial targets include Intel Xae and MIPS R3000/R4Q0O RISC chips. Full cross-platform Windows support won't happen until Win- dows NT CNew Technology) is re- leased, possibly as early as 1993, Nevertheless. the seeds are there now, as evidenced by the in- creasingly reliable DOS sessions in Windows 3.1. Ironically, Windows is often pan- ned for being slow, especially com- pared with the Macintosh- The response has always been that whereas the Mac had very few hard- ware variations (e.g.. display adapt- ers) to contend with, Windows had to be designed in a general enough manner to run on continually evolv- ing systems from a multitude of ven- dors. And lhat made it slow. Now. however. Microsoft's marketing has skillfully turned that "weakness* into a strength. Its not that Win- ADVANCE YOUR ELECTRONIC INTERESTS WTTH A NEW SUBSCRIPTION TO: THE SPEOCOM JOURNAL! Getting your FCC Amateur Radio Li* cense is easier than ever before (NO*CGDE requirement - see R.E, April 91 tssue, pages 27-28). SCj is an 80-page per issue HAM RADIO magazine that covers ALL the spe* cialized modes. Mo^ refunded. Send for Ff^EE facu now. MAIL COUPON TODAY! commatiD pnoDucTions "5 s FCC LICENSE TRAINING, Dept. 90 P.O. &OJ( 2Sa4/San Franclseo, CA 94135 Pleas* njBh FUEE details immediately f NAUE ADORED , CITV .8WE_ 1 I I I I 91 dows IS slow because it has to sup- port such a wide variety of hardware. Windows is powerful, scalable, and adaptable because it can run on all that hardware — plus new platforms bamly a glimmer in the eyes of the designers, Russian dolls Take a good look at Fig. Now draw a box around it, and label the box "OS/2 2.0" (which as we speak does "contain" both DOS and Windows). Now draw a box around that, and label rt "AIX" CIBM s UNIX dialect for its RS/6000 workstations). CAcEualfy you could replace AIX by offerings ffom Dig- ital. HR and others, all of which are based on OSF/1, and all of which will be compliant with the IEEE's POSIX specJ Draw a box anDund that and label it "Taligenf (the joint operating-system company set up by IBM and Apple). To be sure, the last few boxes are speculative — but not by much. Even Windows NT will have a POSfX-compliant Applica- tion Programming Interface (API), as shown in Fig. 1-c, CFor historical fun, draw a small box inside the one labeled MS-DOS. That box repre- sents the CP/M file calls and data structures still present in DOS aPter more than ten years,) At the beginning of this harangue. I said that Microsoft has issued a challenge to the hardware manufac- turers. The challenge can be stated simply: Innovate! Build exciting new capabilities into your systems to at- tract new users, and get present users to upgrade. Windows vast memory space, extendibitity. and ability to vrrtualJze underlying hard- wane together provide an environ- ment in which it is safe to innovate. That s in stark contrast to the DOS years, in which any significant hard- ware innovation was risky to de- velop and expensive to support. Now, under Windows (and the same applies to OS/2), innovations can be accommodated and integrated into the environment This fell wre will start seeing the first wave of X86 personal com put- ers wrth innovative built-in multi- media capabilities, particularly in the area of sound. We'll also see rapid advances in miniaturized machines. If you thought the first ten years were exciting, hold on to your pants— -you ain't seen nothin" yet, 1 can't wait! They're off! As expected. IBM unwrapped OS/2 2,0 on March 31. and Micro- soft released Windows 31a week later Microsoft has gathered a tre- mendous amount of market energy behind its efforts: IBM has so far played it much cooler Big Blue re- leased OS/2 with weak support for everything but standard devices (VGA video and 81-506 compatible hard drives): Windows comes with built-in support for a wide range of devices. OS/2 requires 18-36 megabytes of disk space, and will not work with disk-compression util- ities (e.g.. Stacker). Windows re- quires about 9 megabytes and will work with Stacker and the like, Win- dows has extensive support for run- ning DOS and Windows applica- tions, but not for OS/2 applications. However, compelling native OS/2 applications are stfll rare. Initial tests indicate that OS/2 s Windows sup- port is nowhere near the "better Windows than Windows" that IBM has been aiming for IBM promises to release a much wider range of devfce drivers over the next few months » and is report- edly evaluating the Stacker tech- nology to reduce disk^space re- quirements. Meanwhile. Microsoft will continue to add momentum. New X86's The good news is that Intel has finally released several models of its clock-speed doublers. The bad news is that the technology is not quite as universal as we had hoped. These chips use a phase-locked loop (PLU to run inlennally at twice the speed of the clock signal fed into the device. So a machine with a 25 -MHz bus would run the CPU at 50 MHz. 33 would go to 66. 50 would go to 100 - . . maybe. The problem is that the initial wave of x2 chips are only for 486SX motherboards with "vacancy" sockets, not regular 486DX's. Intel is planning to release x 2 486DXs eventually Cpossibly by the end of the year), but not as user upgrades. It appears that there are several dif- ficulties, including problems with heat dissipation and BIOS incom- patibilities due to liming loops writ- ten around specific clock rates. This means that the 486DX2 might not be an end-user upgrade. Even if it is, don't expect twice the perform- ance; Intel claims an average in- crease of 70%. Initial list pricing will probably be in the $600 range. Intel also plans to release the 586 by the end of the yean we hope to run a detailed technical description of it when it is released. Meanwhile, IBM has developed a few speed-multiplying tricks of its own. You might recall the 386SLC processor discussed here in the past. The 386SLC is a souped-up 386SX that achieves about 80% better performance than a plain 3B6SX running at the same speed. Now IBM says it will release, by the end of the year, a Irne of 486-based devices that runs not only twice as fast as the bus clock, but three, four, and even five times as fest. Running the pnDcessor faster than the bus clock doesn't make much dif- ference if the processor ends up \rt@iting on slower memory devices, so look for large on-chip caches. For years there were persistent rumors that Intel would release a 16- bit 386 that would plug into a 286 socket. No such luck, but Cyrix has done something similar The Texas- based firm, known for X87 math coprocessor clones (and bitter legal disputes with Intel) has released several CPU's that claim to provide 486 performance at 386 prices — and that fit in 386 sockets. One. the Cx486SLC. fits in a 3a6SX socket, but is compatible with the 486SX. The other fits in a regular 32-bit 386 socket, and is also compatible with the 4B6SX. The Cynx CPUs have small caches (1K vs. 8K in all Intel 486 s to date), and do not support burst-mode memory access. None- theless, published reports indicate preliminary findings of 75% perfor- mance increases over 386SX s njn- ntng at the same clock speed, probably due to a singfe-instruction- per-clock-cycle execution unit. A!- though pin-compatible with the 386 devices, th^ will not be user up- grades. Both part name and performance data suggest a per- haps coincidental kinship with IBM's enhanced CPU. R-E BUYER'S MART FOR SALE RESTRICTED lechnica! in^ormatJon: Electronic surveEliance, schemalics. iocksnnrthing, coveri sciences, hacking, etc. Huge selection. Free brochures. MENTOR'2, Drawer 1549, Asbury Park, m 07712, CABLE TV converters: Jerrold. Oak, Scientific Atlantic, Zeaith & many others. 'New MTS" stereo add-on: mute d volume, ideal for 400 and 450 ownersf 1 (800) 826-7623, Amex. Visa. M C ac- cepted. 8 & B IMC, 4030 Beau-D-Rue Drive, Eagan, m 65122. CLASSIFIED AD ORDER FORM To run youf own classJUed *d, pui one word on ea^h of I he linet below ind »f)d thEi foffn itong with youi check to: Radio-Electrontcs Classified Ads^ 500-B Bi-County Souievard, Farmingdale, NY 11735 PLEASE INDICATE in whicli category of classified advenising you wish your ad to appear For s papa I hoadmgs. there is a surcharge of $25.00. i } Plans/Kits ( ) Business Opportunities ( ) For Sale ( ) Education Instruction ( ) Wanted ( ) Satellite Television ( ) . ^ ^ Special Category: $25.00 PLEASE PRINT EACH WORD SEPARATELY. lU BLOCK LETTERS, (No refunds or credits for typesetting errors can be niade unless you ciearly print or type your copy,) Rates indicated are for standard style classified ads onfy See below for additional charges for special ads Minimym: 15 words. 1 2 3 4 5 6 7 8 9 to 11 12 13 14 15 ($46.50) 16 ($49.60) 17 ($52.70) 18{S55.80) 19(S58.90) 20 ($62.00) 21 ($65.10) Z2 (S68.20) 33 (371.30) 24 [S74 .40) 25 [S77.50) 26 ($80.60) 27 ($83.70) 28 ($86.80) 29 ($89.90) 30 ES93.00) 31 ($96.10) 32 ($99.20) 33 (3102.30} 34 ($105.40) 35 ($108.50) We accept Master Card and Visa for payment of orders, if you wish to us© yout credit card to pay for your ad fiU jn the tcJIowir^ additbnat information (Sorry^ no telephony orders can 0€ accepted ): Card Numtror Expiration Oaie PleasG Print Name Signature IF YOU USE A BOX NUMBER YOU MUST INCLUDE YOUR PERMANEf*T ADDRESS AND PHONE NUMBER FOR OUR RLES. ADS StiBMITTED WtTHOUT THIS m FORMATION WILL NOT BE ACCEPtea CLASSIFIED COMMEflClAL RATE: (Icr firms or indivjdu%ils often™ commeroai pioducls or services} S3 to per word prepaid (no charge for ztp code)... MINIMUM 15 WORDS, 5% discount for same ad in 6 issues; 10% discount for same ad in Vi issues within one year Jf prepaid. NON- COMMERCIAL RATE: [for individuals who want lo buy or seiJ a personal item) S2.50 per word prepaid., .n-o minimum. ONLY FIRST WORD AND NAME set m bold caps at no OKlra charge. Additional t)o3d face (nol avaittiblCf as all caps} 55 e p^r word additional. Enlire ad sn boldface. S3.70 per word. TINT SCREEN BEHIND ENTIRE AD: S3.85pfir word. TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD: $4 50 per word EXPANDED TYPE AD: S4 JO per word prepaid. Entire ad in bofdfaco. S5.60 per word. TINT SCREEN BEHIND ENTIR E EXPANDED TYPE AD: $b.9Q per wx]fd. TINT SCREEN BEHIND ENTtRE EXPANDED TiPB AD PLUS ALL SOLD FACE AD: SG.SO per word. DISPLAY ADS: F ■ 2/* — S410 OO; 2" v 2VV—S8 20.00; 3 ^ 2Vi"— S1330 00. General Information: Frequency ratos and preo^^ymcni dificounts are available ALL COPY SUBJECT TO PUBLtSHERS APPROVAL. ADVERTISEMENTS USING PO. BOX ADDRESS WILL NOT BE ACCEPTED UNTIL ADVERTISER SUPPLIES PUBLISHER WITH PERMANENT ADDRESS AND PHONE NUMBER. Copy lo t>e m our hands on the 5th of the third month preceding the date the issue. (i e., Aug. issue copy must bo received by May Sxhi When normal dosmq dale fatis on Salurday, Sunday or Holiday issue closes on preceding wofl<(ng day. Send for the classified orochure. Circto Numbef 49 on the Free Informatiori Card TUBESt new, up to 90% off. SASE, KtRBY, 293 West Carmei Ori^^. CarmeL IN 46032. T.V, notcfi filters, phone recording equipment, bno- chure Sl.OG. MICRO THlnc. Bo^ 63 6025. Mar- gate, FL 33063. (305) 752-9202. TUBES: "oldest." latest." Parts, schematics. SASE for lisis. STEINMETZ, 7519 Maplewood Ave., R.E.. Hammond. IN 46324. LIFETIME Quality Microwave TV Antennas WiatlESS CMU - ERS - MMDS ^ Amaleuf TV yUra HlB^ CaIi ^Odbj^l * Tuneable 1.9 la 21 Ghi. * SS'C^iannef Dish System St99.95 * 36-ChanrM3J D^sh System S149.95 * SO-Charwie! Oi&h Syst&m S 124.95 PHILUPS TECH ELECTRONICS P.O. Boi 8533 * Sct^tt^alu. Al 05252 {Bii2) 947-77110 |S3 DO Credii all phone orttarsj SPEAKER repair All makes — modefs Stereo professional. Kits available. Refoaming Sifl.OO. ATLANTA AUDIO LABS. 1 (600) 56B-6971. ENGINEERING software and hartJ ware, PC/ MSDOS. Circuit design and drawing, PCB layout, FFT analysis. Matliematics, Circuit analysis, etc. Data acquisition, generation, I/O PCB's, etc. Gail or write for free catalog. (614) 491-0832. BSOFT SOFTWARE, INC., 444 Cotton Rd., Colum&us, OH 43207. CABLE TV Equipment. Most type available. Special: Oak M35B S3 a 95. No catalog. COO or- ders only. 1 (800) B22'9955. GABLE TV DESCRAMBLERS ^CONVERTERS* and ACCESSORIES. SAVEMONEY. nnM'T RENT! PANASONIC, JERROLD, OAK, PIONEER, SCIENTIFIC ATLANTA AND MORE. LOWEST PRICES. FREE CATALOG. CABLE READY COMPANY (800)234-1006 FIBER optics kits. Experimenters S24.50. Datalink w/PCB $36.25. HILL ELECTRONICS. Box 47103. PtToentx, A2 65068-7103. CLOCK, 1-32MH2 variable square wavo gener- ator. Request specs, price, TROLEX, 1292 Moarns Rd„ Warminster, PA 18974. CB RADIO OWNERS! We specialize in a wide variety of technical mformation, parts and sen/Sees for CB radios. 10-Meter and FM conversion kits, repair books, plans, higli-performance accessaries. Thousands of satisfied customers since 19761 Catalog $2, CBC INTERNATIONAL P.O. BOX 31500RE, PHOENIX, AZ 85046 JO I 93 THE ELECTRONIC GOUDMINE thm Oaclnnlc M I, AS tfftiE, Fwi LftS n^rt m net f*- JUNCLCl BmD KIT IKIANITT AXAItM KIT wl^m ^ \tf^ iji a/, Lett ^ tj^ b lM 7/ C6240 S6« ZKEXPEKSIVE GEKSER Ortrfls tsr- fMtJ iTL? 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Call Toll Free 1-800-258-1134 C.O.D. M & G Electronics, inc. 301 Westminister Street Providence, Rl. 02903 WIRELESS CABLE RECEIVERS 1.3 TO 2 J GHz » CH PAnABOUC DISH SrSTEi^f H 30 CH ROD mmm system vm go 30CHCRYSiAlC0Nm0l(l0SySrEUl29J 95 SUN MICflOfWAVE litTL. IHi; lEHD SViMFOFl fHOENJX , * OFri E31 mi mi) W VLllEQ PPDQUCTS 80CS2-Basrc microcontroiler board. Basic rnter- preter, 32K HAM, 16K Eprom, Eprom programmer, RS232. expansion connector Bare board with manual p sctiemaiics S22.9S. 80C 52- Basic micro- processor chip S25.9S. Assembled and tested $124.95, PRO LOGIC DESIGKS, PO Box 19026, Baltimons, MP 21204. JERROLD, Tocom and Zenith "test" Cflip3- Fully activates unit S50.00. Cable de- scfamblers from $40.00. Orders t (BOO) 452-7090. Information (310) 867-0061. FREE CATALOG FAMOUS 'TIRESTIK'^ BRAND QB ANTEHHAS AND ACCESSORIES, QUALITY PRODUCTS FOR THE SERIOUS CB'er. SINCE 1962 FIRESTIK ANTENWA COMPANY 2614 EAST ADAMS PHOENIX, ARIZONA 85034 TOCOM'Jerrold Impulse-Scientific Atlanta Gonvcrteis, tv*'o year warfantSes, also test mod- ules tor yourconvertofS. Contact NATIOMAL CA- BLE, (219) 935-4128 futl details. TEST- Aids for resting units in lull service mode. Starcom VH, S40.00; Starcom VI, S30.00: Star- corn OPBB S50.00; Pioneer, S75.00; Tocom VIP 5503 '5507. S25,00; S. A. calt; Zentth, S25.00; N.E. ENGINEERING, (617) 770-3830. CABLE equipment... wholesale only. Starcom 7 test ki[5 $18.00. New tags irom S25.00. New converters from S55.00. SA DP Pans trom S4S.00. Starcom 6 factory Trl^bl combos from S99.00..., in quantity to the trade 1 (800) 866-2232. RECErVING TUBES OVEB300Q TYPES IN STOCK* Also iiard'to-find transformers, capaci- tors and parts lor tube equipment Send $2 00 tor our 32 page aWog. ANTIQUE ELECTRONIC SUPPLY 6221 S. Maple Ave.'Tempe, AZ 85283*60M20'5411 CABLE test Chips S A 8550. S-A 8500 — 310, 311, 320. 321 (Specify) — $33.95. S-A 8530/338 — $69.95, Tocom 5503/07 VfP — 533.95. TELE- CODE, PO Box 6426' RE, Yuma, AZ 85366-6426. OSCILLOSCOPE 50 MHz. Hewlett-Packard, sol- id State calibrated, manual $290.00. 1 (000) 835-8335 X-159, CABLE cof^verters. all brands in stock at un- believable prices, example RTC-56 at $69.00 ea. in lots of 5. SVL 4040 DIC S59.00 ea, in Ids of 5, Zenith and Tocom test chips 329.00 ea. in lots of 5. We now carry the PTD phono tap detector al S69.00 ea. with quantity discounts available. MOUNT HQOD ELECTRONICS. 206-260^0107. CABLE TV, Zenith, Tocom. Oak. Hamlin, Jerrold. Pioneer at discount prices. Tocom and Zenith test chips 5 (a S29.00 ea. S.A.C., 1-800-622-3799. M- F 7AM-3PM P.S.T l^A^D, GENERAL mobile radfost CB's scan- ners, radar detectors^ auto alarms, marine transceivers catalog S2.00f Rays, Box 14862RE, R. Worth. TX 76117-QB62. SECRET cable de scramblers. Build your own descrambier for less than Si 2. 00 in seven easy steps, Complele instructions $10. 00. Radio Shack parts list and free descramblfng methods that cost nothing to try included. HARRY WHITE, PO Box 1790O. Baytown, TX 77520. SELLING test Chips for Zenith, S A. and Jerrold. also lumed-on boxes at best prices. Buying raw boxes. Cajlj05-425*437fl. LOW cost logic analyzer — A must for compa- nies and serious hobbyists: 8 digital inputs, sam- pling rale from 50 nsec to 1 msec Connects to PC or compatiblo via RS 232, Only $250,00 US, For info: OPENTEK. PO Box 71, SoreL Quebec. Can- ada. J3P 2T6. ASSi^^SLY services. We quote and assemble printed circuit boards. Competitive cost and quall- ly TEXAN A, (512) 572-3361, CABLE TV. all make and modal converters- desc ramblers In stock, low tow prices, testing chips for Tocom and Zenith S29.00 ea. All products carry a full warranty. We ship C.O.D. Now stocking the P.T.D-1 phone tap detoctor $69^00 ea. Catalog and orders calt, KABL£ KONNECTION (702) 433-6959, No Nevada sales. DESCRAMBLERS, converters, Z-TAC S199.00 ea. 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