BUILD A PC-BASED TEST BENCH! TECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVICE BUILD THIS ROBDT "BUG" Lt'j? Liiiu till* s;iuiL'ti^si Ll-o-L'Ii a tat imLii it VIDEO AMPLIFIERS HARD-DISK DRIVE STANDARDS BUILD A SOLID-STATE THERMOSTAT rxxsxxxx CflK-KI 75045SHRR5i65MQ93 S2.95 U.S. S3.75 CAN GERNSBACK XX. CRQ j □6 18 NOM 93 RE We Only Skimped OnThe Price. Introducing The Fluke Series 10 — From $69.- Aclual sfze: Eas/ Id carry, easy to use Hml V Oiefc^ for fast accurate checks m power sources and supplies, set vt>ur meief on V Chsk— ^tet itdotherest VCfiek will determine contmuity/ohms: if voltage is present it v^ill autamtjc^lfy change modes to measure AC or DC volts, whichever is detected. For rBost initial iroybleshDoting checks. Here's the only setting you need to makg. y: Made in the USA by RuVe. ! Hit same rugged refiabiliiy that's made us the v/orld leader tn digital multimeters. Count on hard-worl^irg high peflofmance— and a two-year warranty to back it up. Large » easy-to-read display: 40QQ count digital readout Audible Continuity: To perform fast continuity checks, jusl listen for the beep: no need to watch the display. CmCLE 121 OH FHEE O^FOfUiATION CARD //ekv/ M in/Max record witfi relative time stamp and Continuity Capture": Makes intermittent problems easier to lind. f^ecofds highs and lows— and lime stamps" when they occuned. In cominurty mode, opens or shorts as bnei as 25G ^s are captured and disptayed. Capacitance: Autorangmg Irom .001 tiF to 9999 }iF. Wo need lo caiiy a dedicated capacitance meter. For high perlormance at Fluke's lowest price, get your hands on the new Series 10. Stop tiy your local Fluke distribulor and leel what a powerful difference the right mulbmeier makes— at the right price For a free pmduct brochure of the name of your nearest distributor, call 1-80D-87-FLU1tE Assist Oofle Te$t Sleep TwD-yeit warraivty lit PCriiD999f |iF 1 $V bisc at votts 0 9% Dastc dtim5 accuracy f3flconlintiity 0<0(3eTe$i Sleep Mode Twe year warranty VChrt " IfiaVaj nca&fig CcRTtftuiity Casnure™ CamctUncf 4000 couni i!igrai djfpta^f 0.9S b3%tc lie vQ^s accuracy 1 9V baste 3C vtiM 0.9% Eu^k: crimt accirrac/ fast cqniinulty Sle«o H«K]e Two-yeaf warrsniy SuggesiedU S. hit {(rice The New Series 10* A Small Price For A Fluke. F L V K E A NVn P H J L I r T ft K T M ALLIANCE 0199t JofmFluitMrg Co Jnc PiK^ms^ftK^lmi sobiictiactiar>g» Aam 00130 June 1992 Vol. 63 No. 6 33 BUILD THIS ROBOT BUG A fun — and inexpensive^ — robot project. Roger Soiintag and Dennis Chaney 53 ELECTRONIC THERMOSTAT Replace mechanical units for under $20f Rodney A. Kreuter 57 CLASSIC VIDEO AMPS REVISITED Mature amps still have lots of life for new video and RF circuits. Edgardo Perez 39 PC BASED TEST BENCH In this first of a series, learn how to build an interface card. Steve Wolfe 63 THE INSIDE STORY ON HARD-DISK STANDARDS A look at today's competing disk-drive standards. Byron Miller 6 VIDEO NEWS What's new in this fast- changing field. David Lachenbruch 16 EQUIPMENT REPORT Multidyne TS-S-MTS TV test signal generator. 69 HARDWARE HACKER FM stereo broadcasters, and more. Don Lancaster 76 AUDIO UPDATE Testing the testers. Larry Klein 84 COMPUTER CONNECTIONS Windows 3,1 and OS/2 2.0 Jeff Holt2man PC-BASED TEST BENCH t«i mm *rr*r «rtic«H PAGE 39 THE INSIDE STORY i*^ ON HARD-DtSK STANDARDS r. ',v>rM, d^-JOAHTJi. M*** , ....■l'.,,«Kr» lt«f»C«ff fMbrV PAGE 63 98 Advertising and Sales Offices 98 Advertising Index 12 Ask R-E 14 Letters 85 Buyer's Mart 28 New Lit 22 New Products 4 What's News i P % 9 m 3 ■3. t ON THE COVER S3 I c 9 o LiJ 6 cd aUILDA Pt^aASEO nST BENCHM □ If you're looking for a robot to serve you drinks, balance your checkbook, and cook your meals, dream on! If you're lookmg to learn about robotics by building a simple, inexpensive, and fun project, check out our Robot Bug. The free-roaming robot can sense and avoid obstacles to find a path through its environ- ment. It has two switches — similar to an insect's antennas — that re- spond to a touch by causing the robot to stop, back up, and turn away from that side. Turn to page 33 for the details. THE JULY ISSUE GOES ON SALE JUNE 2. BUILD A STEREO TRANSMITTER Use your portable CD player in your car with this easy-to- build device, PC BASED FREQUEIMCY COUNTER AND CAPACITANCE METER Our series continues with instructions for these low-cost, hrgh-quality PC- based test instruments, BUILD THE CRANKING AMP ESTIMATOR This high-tech device will let you know the condition of your car's battery. WORKING WITH OPTOCOUFLERS Put optocouplers to use in your designs — including transistor- and SCR/ Triac-output devices. As a service to rpaders, RADlO-ELECTftOMECS publishes sveilebre p^ans or information relating to newsworthy products. tacKritC|:Lte£ scientific end lechnolo'gical d^velopmiinTs. Because of po&s-ibl^ v^ar^ances in ihe quafity jiind condrt^on of rr^Aterials end vrorkm^nshrp used fay readers. FLADIO-ELECTRONICS disciaims any rssponsibitity for th^ %ah and proper fundJoning of reader-built projects based upon or from pEansor informaeion published intliis niagazin«. Since ^ame of Llti^ equ^prrient and circuitry described iin RADlD-ELECTRONiCS may relate to or be covorvd by U^S. patents. RAOiO-ELECTRONlCS dtscfaimsany Ifabilrty for the mfringemeniof s-uch patents by the malting, using, or seriing of any such e^iuiprnent or circuitry, and auggests that anyone interesled io sue IS projects consult a patent attorney. RAOlO-ELECTftONtCS. (ISSN O033-7862) June 1992. Published monthly by Gernsbatk Publications. Inc., SOO B Bi County Boulevard, Farniingdalo, NY fl735. Second-Class Po&tnge paid at Farmrngd^alo, NY and fidditional mailing offices. Second- Class nnail registration No. authorized at Toronto, Cnnada. One-yenr subscription mte U.SA and possessions SI7,97. Canada $2S.5S (includes G.S.T. Canadian Goods and Services Tax ^gistraition No. Rl25l€€230}, all other countries S2G.07. All subscription ordors payabTe m U S A, funds only, via international i>ostaE money order Of check drawn on a U S.A. bank. SingFe copies $2.95. 1992 by Gornsback Publications, Inc. All rights reflerved. Printed in U.SJ^. POSTMASTER: Ploaso send addrssfl chitngss to RADIO ELECTRONICS, Subscription Dept., Box 55115. Bouldor, CO B032t-51]5 A stamped seCf- addressed envelope enust accompany all submitted manuscripts and/or artwork or photograpbs if their return is desired should they be rejected. We di:sclaim any re3(K3 Fentont editor Marc Spiwak, associate editor Meil Settle Ft associate editor Teri ScadutOi assistant editor Jeffrey K. HoJtzman coitiputef editor Robert Grossblatt, circitits editor Larry Klein, audio editor David Lachenbruch contributing: editor Don Lancaster contributing editor Kathy T«nnxh editorial assistant ART DEPARTMENT Andre Duzant, art director injaa Lee, M lustra tor Russell C. Truelfton, ilkist^'ator 1 PRODUCTION DEPARTMENT Ruby M. Yee, production director Karen S. Brown advertising production Marcella Amoroso pro d u ctf on a^s i sta nt Lisa Rachnwitx editorial production CIRCULATION DEPARTMENT Jacqueline P< Che^seboro clrcolation director Wendy Alanko circulation analyst Theresa Lombardo circutatton assistant MIchoie TorrillOi reprint bookstoriAT WITH etM.T IN tOQC IH£A«0AT, DfiCODER DR[VERS9 rmj. ALPHA CHAAACnRS m TWO UlOEl»fllOCMT CLOCKS USE^ A£UUSIAllf FftfOUO«CY ft MJTT CYCLES ■ BHCAOBCUItthSOS PT PnOTQ-TTPE AREA TWO i^nvEn oorntmoH Mi^cs iMv«) m 4 DATA BIT SMTOCS ■ ItOUEHTAin P\jm 0UTTOM 5WTTCH (SPUn ■ 4 L£D CMSPLAYS wIC DRIVERS ■ POWER SUPPLV: WALL PlUO^ TYPE. UJ^ LtSTED ■ UOLTAae REO^S VOLTS, SHORT OR. OVERLOAD PROTECT ■ HOOK-UP WIRES ■ COMPACT CARRVINO CASE ■ INSTRUCTION MANUAL FOR BEOINNER TO ADVANCED USERS MADE WfTHPmD£ m THE i/SA FRBECOMPREHENSfVE TEACHER^STU DEfCr LAB MANUAL KELVIN Laptop Digital Trainer ONLY $99 95 Stock No. 840460 WALLTRANSFORMERS ■breadboards WALL TRANSFORMER STOCK MD fTf 22O069 ty DC ^ mA 2200£8 i7VP0MQ>inA MALE JACK 370040 M mm Malo COMPONENTS Sioch Mo. ^ypi •o-.Ts ecu 600021 5S5 TIMER. ...*.20i^ GOO029 556 ouAL Tiinn * .40 ia 600039 LM566 PLL » m 6000 1 fi 74 1 C OP AUP .30 600026 1 458 oP- auf _. * J5 t ^ 630041 2N2222 MSt. 6303B3 PN2222 *.08r* S00023 7305 vcL.TAQE ma^ .36 1 4 SILICON CONTROLLED RECTIFIER tStmillar to GtL CipQCl] A,Q AMP. 10Q t^V 600014 '.89ea *,79(A5Cf. 65^:^5 MO 100 SSSC* Nfi Pill C^taat . - Tt3i^C05t 660093 0 500 * 4.^ 660037 0 840 * 5.** 6$(K}9a 2 1380 660100 4 2390 ■■■■ ■*22.*^ WIRE ^^^Wv JUUIPEH KIT /.£f»^^p- ■ 3303S9 140 Piece S^-r....* 4.^* 330250 350 Piece Set .... * 7.^' FLUKE 7^ S ^in^H BEST BUY NEW Scrtcs n FLUKE 70 » 63 FLUKE73s*««ii ,. » 89 FLUKE75s^i«ii *127 FLUKE 77 stn^u . .^ *149 FLUKE 79 s*rt«ii »169 FLUKE 83 '21 9 FLUKE 85 '259 FLUKE 87 w^n.^. '289 FLUKE 66 ALiroMOTPvr >367 FLUKE 68 ^LjTo«m«t =423 FLUKE 45 '599 FLUKE 12 * 83 SPECiAl SPECIAL RED LED As Low Ab JUMBO LED TITPE . Till. Sfwn: 2600201^ ^.06«*iiib *.05m 260077 Own VOB » itMK * ,Q7 n 260026 Y»Da^*. OS Ml DD* *.07«j LED HOLDER lO^ T 1 14 SIZE. BLACK $toch Ho. *.10f* W-4.50cB P r o ^ ^ c I Speaker r.foiw, 1 WfTt 59 e P f Q i e c r BUZZER 3 ■ 9 Vott DC. BO db S40LESALE PfUCED ITEMS. OVER 10,000 rTEMS m STOCK ELECTRONIC COMPGflEKT^ ft TtCHNOLCKlY ACTtVmES Vl^A i UASTERCARD ACCEPTED 120 MINIMUM ORDER MmiMUM FREIGHT S5 KEL VIN Established 1945 10 HUB DRIVE MELVILLE, MY 11747 (800) 645-9212 (516) 756-1750 (516) 756-1 763/FAX to P J} 9 m to 3 CLRCL£ 190 ON FREE INFORHATION CABQ WHAT'S NEWS A review of the latest happenings in etectronics. High-brightness green laser A 52'Watl green laser beam gen- erated by researchers at the GE Research and Development Center in Schenectady, NY, more than dou- bles the previously published bright^ ness record for green light pro- duced with solid-state lasers. As used in optical physics, "bright- ness" refers to both power — the watts of photon energy put out by the beam— and beam quality — a measure of the beam's diameter and how much it diverges or spreads out. To produce the high-brightness green beam, the GE researchers passed a 16- watt beam from a com- mercially available solid-state laser through a telescope and other op- tical elements, and then fed it into a specially built neodymium-doped yt- tnum-aluminum*garnet (Nd:YAG) face- pumped laser. That process amplified the beam to 92 watts while retaining the good beam quali- ty. The 92 -wait beam was then passed thrDugh a focusing lens and fed into a crystal of lithium triborate that acted as "frequency doubter** GE SCIENTISTS HAVE GENERATED A 52-WATT GREEN LASER BEAM, more than doubling the previously published brightness record for this wavelength of light produced with solid-state lasers. 1990 1997 DIP 41% so 22% 0IP3% SIP 12% SO 36% MCW4% CC12% ccurs PGA 11% OTHER TS% KEY: SO: SMALL OtJILINE WCKAEE OPDUALrff-LlNERftCKAGE StP: SINGLE tH LINE WCK^GE PGA: PIN-GRID ARRAY CC: CHIP CARRIER MCM: MULTICHIP MODULE SOURCE: MIRC FIG. 1— The changing world market of IC component packaging Is eKpected to change markedly between 1990 and 1997, Percentages shown indicate revenues by type of package. and halved the beam s wavelength to 532 nanonneters. That produced the 52 -watt green beam in combina- tion with an invisibfe infrared beam. The two beams were passed through a dispersing prism to sepa- rate them. The research is part of GE's efforts to demonstrate new applica- tions for its face-pumped laser tech- nology, which is currently used in high speed, high-precision metal cutting and dritling at GEs aircraft- engine manufacturing plants. The green beam, alone or in combina* tion with infrared beams, is well ab* sorbed by certain polymeric com- posites and might be suited for cutting and drilling them. Because seawater is essentially transparent to a green beam, the laser might be used In submarines for underwater detection and commonications. With additional frequency con- versions, the green beams can be shifted to wavelengths in the ultra- violet and deep ultraviolet regions that are used in laser surgery and other medical applications, without significant power loss. At present, only excimer lasers can appmach such applications. New IC packaging According to a study recently re- leased by Market fnteffigence, strong growth in the IC component market — from $50 billion in 1991 to more than $106 billion in 1997— will be largely due to new packaging technologies. Surface-mount tech- nology CSMT) surpassed through- hole technology as the leading elec- tronic systems manufacturing tech- nology for new designs in 1991 . The shift from through-hole technology to other packaging technologies will be fueled by increased operating speeds and the need for higher pin counts. As world consumption of dual-in- line packaged (DIP) IC's falls from 41% in 1990 to less than 3% by 1997, other technologies will fill the gap (Fig. IX There is a clear trend toward specialized packaging by in- dividual iC and application type. With the fastest growing packaging technologies expected to be small- outline CSO) packaging, multichlp modules CMCM), and quad flat packs CQFP). The SO package is expected to gain the largest indus- try segment, rising from 22% in 1990 to 36% in 1997. R-E Ybu Can AiWAYS Spot IhE IteHNEUN IMD DOESNl Use ItKHIX. If you're sending technicians and FSEs into the field with equipment other than Teldronix, don't be surprised to discover some unusual tools in their seiviceldts. Signal flares, for instance On the other hand, portable test gear from Tek gets technicians to the root of ^ the problem long before the problem gets to them. Everything from osdllosoopes and spedmm analyzers to handheld DMMs. As a result, your customers will be bad on their feet I happy for that Not to mention a whole lot nicer to ■ in whatll seem like no time at all They'll be f work with. For your employees' sake, get in touch with a Tektronix representative today. Or keep an eye peeled for signs of distress. TALK ID 1IK/1-8DD-42G-22DD Tektronix y^isX and Measurement (13W-ia8149 CopyfigW^ 1591, !5klr(siii«.lnc CIRCLE 1 B2 ON FREE INFORMATION CARD Whafs new in the fast-changing video industry. DAVID LACHENDRUCH • TV and X-rays, Those of yoy who are at least 40 years old may remember the Great X-Ray Scare of the 1960s. Articles about the pos- sibility of severe radiatiorr exposure of TV viewers were widely pub- fished, and specific data on rats bred tr^ the vtcinity of network broad- casts allegedly showed mutations. Supermarkets sprouted "X-ray de- tectiort kits" to tell consumers whether their TV's were leaking ex- cessive amounts of radiation. Congress got in on the act and passed the nobly- titled "Radiation Control for Health and Safety Act of 1968/* Among other things, that law was intended to limit radiation from TV sets to below the level of back- ground radiation — certainly an ad- mirable goal — and let parents permit their offspring to view TV with complete assurance that even if it would endanger their impres- sionable brains, it wouldn*t hurt their bones and other vitals. The U.S. Public Health Service promulgated rules to save the Amen ican people from X-ray zapping by color TV. Basically, those involved the use of special high-voltage hold- down circuits in TV sets to keep power supplies below the danger level, the addition of more shielding in picture tubes, and the develop- ment of testing pn^cedures to make sure that no radiation developed within the TV sets. Among those test procedures were factory tests with all user and servicer controls set to produce maximum radiation. AC line voltage at 130 volts, and simulated failure of any component that could possibly cause excessive radiation. In addition, dealers and dis- tributors were required to keep the names and addresses of TV- set pur- chasers for the "useful life" of the set. Alnnost immediately after the ra- diation rules went into effect, the TV industry v^nt to solid-state circuits, eliminating the power tube that was classified as a major source of radia- tion. Despite the switch to solid stale and the heavily leaded glass in picture tubes, the regulations weren't changed. Ten years ago. the Public Health Service proposed eliminating many of the unnecess- ary feguiations, but nothing ever happened. When we asked, nobody at the Public Health Service could re- member the last time a consumer TV set was found to be radiating above the strict minimum. Never theless. the tentacles of the law reached out last year and nabbed a manufacturer — not for permitting excess radiation, but because of what the Public Health Service called improper test procedures. It impounded 30,000 sets made by that manufacturer. The manufac- turer held up another 130,000 sets until everything v^s cleared up. los- ing most of the major Christmas selling season of 1991. Not one of the 160.000 sets was found to be radiating, but ... the laws the law, and inspectors visiting the factory found that the company wasn't fol- lowing the right test procedures. Asked the reason for the over* reaction, a Public Health Service of- ficial involved admitted candidly that it was because of the widespread criticism of the Food and Drug Ad* ministration for laxness in enforcing its regulations on testing drugs and such devices as silicon breast im- plants. Partly as a result of the ridiculous crackdown on the TV manufacturer, the EIA is now seek- ing a revision of the government s X- ray regulations for TV sets to avoid futum problems. • lnterac:ttve TV. Hewlett-Pack- ard is the latest American data-pro- cessing name to say it will have a go at the TV industry. HP has an- nounced that it will make home in- teractive terminals for the TV Answer two-way television system. TV Answer might roughly be de- scribed as the video version of Pro- digy. Unlike many proposed pay- per-view systems. TV Answer isn't designed to charge the consumer more for using his or her TV, but it is intended to provide home shopping, educational, and polling services, including participation in game shows and the like. The FCC recently allocated spec- trum space to Interactive Video and Data Services tlVDS) at the re- quest of TV Answer. TV Answer has a deal with Hughes Network Sys- tems to install "very small aperture terminals * CVSAT's) for transmis- sion to satellites in a cellular-type network. TV Answer expects to be- gin service about a year from now. if the FCC acts on its promise to choose the first allocations by lot- tery by the end of the year HP says that its home terminals will cost about $700 at the start — "lower than the first VCR or the first CD player" — but concedes that prices could "decay rapidly" • Better, cheaper LCD*s. Can Amenca solve the liquid-crystal dis- play logjam? One company. In Focus Systems of Beaverton, OR. is betting that it can. In Focus says that it has developed a passive ma- trix LCD system that it believes can solve the problems posed by active matrix systems — ^low yields and high costs. In Focus is pushing a system called 'Active Addressing," which it says solves the problems of passive matrix systems without the problems of going to active matrix. The system, in effect, takes the complexity out of the display and puts it in the electronic addressing system. Although In Focus products currently are designed for the com- mercial and industrial markets — particularly, computing — ^the com- pany s new technology, not yet in production, could result in a major breakthrough tor such video de- vices as flat- pane I TV sets and proj- ection TV's. R-E Now, You Can Eavesdrop On The Worid. Introducing the new Drake R8 Communicalions Receiver. It's world class, world band radio, made-in the U*S.A- From Perth to the Persian Gulf, Moscow to Mozambique, local or global, you hear events as they happen with amazing clarity. Since 1943, Drake has been setting the standards in electronic communications, . , and then rising them. Today, there's no better shortwave receiver than the Drake R8, Out-Of -This- World Performance* The new Drake R8 has more standard features than other shortwave radios* You get wide frequency range (100 KHz to 30,000 KHz), coverage of all world and local bands, and excellent dynamic range. But you also get important features you won't find on receivers costing hundreds of dollars more. A muld-voltage power supply. Pre-amp and attenuator. Five filter bandwidths and synchronous detector* Dual mode noise blanker and passband offset, Non- volatile 100 channel memory. All designed to give you the b^ reception with the least distortion. Down-To-Earth Design. The ergonomic design of the R8 gives you real ease of operation. You have convenient keypad entry, with large, legible controls. The face is bold. Uncluttered. And the liquid crystal display (LCD) is backlighted for easy reading. Tiry The R8, • . At Our Risk. If youVe not impressed by Drake's quality, performance and ease of operation* return the R8 Receiver within 15 days and we'll refund your money in full, less our original shipping charge. For more information, or to order, call TOLJUFREE, 1-800-9-DRAKE-l . Telephone orders may be placed on a major credit card. S979.00 (Shipping and handling $10 in continental U-S. Ohio residents add 6»/2% tax.) Call TOLL-FREE, 1-800-9-DRAKE-l today. You can't lose. DRAKE b In touch with the world. RX. Drake Company • RO. Box 3006 ■ Miajnksburg, Ohio 45342 U.S, A, CIRCLE 176 ON FREE iNFOfiHATlOM CARD If Youtwe Serious About a Fkiture in Electronics, Ensure that Future with the Best Educational Ife'aining Available. Lf you wane to learn about electron- :s, and earn a good rncome wrth that nowledge then CJE is your best ducaiional vaJue CIE s reputation as the world ?ader in home study electronics is ased solely on the success of our raduates. And we've earned that sputation with an unconditional ommitmcnt to provide our students .'ith the very best electronicy ^aining. Just ask ny of the * raduates of ■ t^i ^ :^ / i^e Cleveland B ^--^t '^m W ' istFtute of H t ^ ledronics m^^^ /ho are /orNing rn irgh-paying osttions with erospace, omputer ledicalp u to motive nd communi- ation firms hroughout the ^orld. They" II teN you success didn t ome easy... but it did comc^.. -thanks o CIE. And today, a career in elec- ronics offers more oppK^rtunities and greater rewards than ever before. HE'S COMMnTED TO BEING THE BEST....JN ONE \REA,.„ELECTRONJCS. ;JE isn t another be-everything-to- ? very body school- We teach only one ubject and we believe we re the best it what we do. Also, CJE is accredited )y the National Home Study Council. \nd with more than a 1,000 gradu- =ites each year, we're the largest iome study schooJ specraJIzing exclusively in electronics. CIE has 3een training ca ree rnn in ded students ike yourself for nearly 60 years and ve're the best at our subject ..... iLECTRONICS BECAUSE ITS THE DNLY SUBJECT WE TEACH! CIE PROVIDES YOU WITH A LEARNING METHOD SO GOOD, IT'S PATENTED. CiE's Auto- prog rammed Jessons are a proven learning method for building valuable electronics career skills* Each lesson is designed to take you step>by^ step and principle-by-principle. And while iiil CIE lessons are designed for independent study, CIE's instructors are personally available to assist you with just a toil- free calL The result is practical training.,, the kind of expeh^ ence you can put to work in today's marketplace. LEARN BY DOING„.WrTH STATEOF- THE.ART FACILJTJES AND EQUIPMENT. In 196% CIE pioneered the first Electronics Labora- tory course and in 1 9S4, the first Mircoprocessor Laboratory course. Today, no other home study school can match CIE s stale-of-the^art equip- ment and training* And all your laboratory equip mem, books, and lessons are included in your tuition. It s ail yours to use while you study at home and for on -the -job after graduation. PERSONAUZED TRAINING,,, TO MATCH YOUR BACKGROUND. While some of our students have a working knowledge of electronics others are just starting out. That's why we've developed twelve career courses and an AJKS. Degree program to choose from. So, even if your not sure which electronics career is best for you, CIE can get you started with WHY CHOOSE CIE FOf? YOUR TRAINING? " 150.000 successful graduates from every country around the world* ■ Only CIE rewards you for fast study, CIE offers an Associate Degree program based on actual study lime used. The faster you complete your degree the less your overall tuition. ■ State-of-the-art lahoratofy equipment is yours to keep and it comes assembled, ready for hands^n experiments. ■ Approved for educational benefits under the G.L Bill for veterans and other eligible persons. ■ Upon graduation^ CIE offers free preparation to pass the Certified Electronics Technician Exams. core fessons applicable to all areas of electronics. And every CIE course you take earns you credit towards comple- tion of your Associate in Applied Science Degree. So you can work toward your degree in stages or as fast as you wish. In faa, ClE is the only school that actually rQw^\rds you for fast study, which can save you thousands of dollars. SEND TODAY FOR YOUR CJE COURSE CATALOG AND WE LL SEND YOU A FREE 24 PAGE CIE ELECTRONICS SYMBOL HANDBOOKl □ YES! i want to get started. Send me my CIE school catalog includ- ing details about the Associate Degree Program. (For your convenience, CIE will have a representative contact you - there Is no obligation. f AE39 Name; Address:. City , State: Zip: .Age: Pnofie No. f ) Check tjoit for G.l. Bulletin Beneftti G Veteran ' j Actrve Duty ////Si CLEVELAND \ ^ CLEVELAND INSTITUTE OF ELECTRONICS 1 776 Easr 1 7lh Street CfGv eland, Ohro 44114 £2161 73 1-9400 ASK R E Write to Ask R-E, Radio-Bectronics, 500-8 Bi-County B!vd, Farmingdale, NY 11735 FIG. 1— A VIDEO WAVEFORM is an ejctmmely complex signal. It you would like to know how your local cable company does their scrambling, take a few scope photos of the scrambled signal or make some sketches of it, and send them fn to us. TV SCRAMBLE fve been tinkering with video signals, and Tm impressed at just how complex a video signal is. rm amazed that cable com- panies can "scramble" and ^'de- scramble*' the signal, I under- stand that each cable system has its own scrambling method. What exactly do they do to the video signal, and how can I de- termine what scrambling meth- od my cable company uses? — G- Fischer, Deppee, NY The fact tiiat a video waveform is an extremeiy complex signal is ex^ actly what makes scrambling possi- ble. All the cable companies have to do is mess up just one part of the signal for Ifie picture to become un- viewable. Descrambling circuitry lo- cated in thie box provided by your cable company is then used to re- store the original signaL rd love to be able to tell you ex- actly what your cable company is doing, but there are many different ways to scramble video. The meth- ods used by cable companies are constantly changing in order to keep one step ahead of the "illegal" descramblers that always show up. In general, most scrambling methods involve some manipulation of the control portion on each line of video. And since the major player is the horizontal-sync signal Csee Fig, 1), that's usually the one that gets messed up. If you take away the horizontal -sync signal, the TV wori*t ^ be able to tell where each line ends. S When that happens h the horizontal ^ flyback in the TV will freewheel, and ^ you'll most likely see the entire hori- g zontal interval weaving down the E center of your TV screen with the % left part of the picture on the right □ side of the screen and the right part k of the picture on the left. J Sometimes the picture portion of the video sjgnal is inverted, so you'll see a negative image or> the screen — or at least that s what you 12 would see if they didn't also mess up the horizontal sync. To make matters even worse, the current trend in scrambling video is to do different combinations of these things on each frame of video. The information needed to decode the next frame of video is usually buried in one of the off- screen video lines present in the vertical interval. We don't know just how many different methods are used by cable companies to scramble video, but we*d like to find out. We encourage all readers to take a few photos of the scrambled signal as it appears on an oscilloscope, or make some sketches of it, and send them in to us. If you know what scrambling method is being used, make a note of it. If you don't, we'll try to figure out what they're doing and get back to you with the answer eO-HERTZ HUM I live in an apartment and have a fairly elaborate audio system with speakers in every room. Recently, I moved the amplifiers to another part of the living room and since then Tve been plagued with high levels of six- ty-cycle hum. Is there anything I can do to gel rid of the inter- ference short of moving all the equipment back to where I origi- nally had it?— B. Meredith, New York, NY The problem of sixty-cycle hum is always hard to solve but the first thing you have to do is find out ex- actly whene it s coming from and. as soon as you know that, you can start to deal with it. Until you know the source of the hum. anything you try to do is wasted effort. Start by shorting out the inputs of your equipment, beginning with the power amps and working back to the tape decks, tumtables, and so on down the line. If the hum disap- pears when a particular input has been shorted, disconnect whatever is feeding that input and see if the hum disappears. If it does, you've got a grounding problem in either the cabfe or the equipment feeding that input. If the hum remains, you've got a problem with the input or power supply circuitry in that piece of equipment, and that's where you should begin your search. This wham-bam method of hum detection is great for locating faulty components, but it's also possible that all your stuff is m perfect con- dition and you're simply the victim of the friendly folks from your local power company. Unless you live deep in a cave, on the top of a re- mote mountain, or on an unin- habited moon of Neptune, you're spending your days surrounded by a continued on page 15 ELECTRONICS FKOIECTS As a member of the Electronics Book Club * . . , . . you'll enjoy receiving Club bulletins every 3-4 weeks containing exciting offers on Ihe latest books in ihe field at savings of up to 50% off of regular publishers* prices, Youll always have at least 10 days to make your decision. If you want the Main Selection do nothing and tt will be shipped auto- matically- If you want another book, or no book at all simply r^urn the Reply Form to us by the date specrfied. Your only obligation is to purchase 3 rrore t>ooks during the next 12 months, after which you may cancel your membership at any time. It coupon is fms^ing. wftlt to: Soolc dub. BluB F%idgff Sttrnmlt. PA \7ZM6W ^ELECTRONICS ^BOOK CLUB-^ Blue Ridge Symmit. PA 17294-0610 Please accept my membership in the Electronics Book Club and so nd the 5 t^ooks listed below billing me S4 95 plus shipping/handling and applicable sales lax. tf not satisfied for any reason, I may relurn the books wllliln 10 days and have my member- ship cancelled, I agree to purchase 3 more books at regular Club prices during the next 12 moaihs and may resign any lime thereafter. Cod« iitimbers of my 5 se1eciion« for $4.95 P I m Nzme Address City, . Oftfit valid lof HitA TTwnbers only, tubfaa ra wacnpnasKm Dy ESC. ApplNianiri autud* Erie u.S nrKj CtnaUM -m^l r«c«rv« sp«t;ial Drd^ringi inglructtofiB. C&nttlt rmi$l arvn \n U S- Fynd9. Ail bocki tf* har^covnr unlftsi orh^rwrs^ nfnad. .State ZJp 13 your most compfete and comprehensive source for the finest electronics hooks LETTERS Write to Letters. Radio-Electronics, SOO-B BhCounty Blvd. Farmingdale^ NY 11735 MONITOR TEST CORRECTIONS Some errors appeared in our "Monitor Tester"* article CRadio Electronics. January 1992X First, the two Schottky diodes in Fig, 1 CD2 and D3) were shown backward. Second, the input connection to IC1-C Cpin 5) should jump two lines to the left to the "PSEUDO 3D EGA2" line instead of being con- nected to ICS pin t2. Third, the inter- section dot at J2 pin 1 should be removed — as it was shown, rt wrongly grounded to output of ICl- d. And last, resistor R14 should be removed from the parts list. SEEfNG THE LIGHT IVe been reading your great mag- azine for decades, and it's still as fascinating today as the day I dis- covered it. Recently, something happened that I feel must be shared with the other readers of Radio- Elect ronics. Back at Christmas time a friend and I were standing in the light-bulb aisle of Builders Square talking about the merits of different types of light bulbs. All of a sudden, with- out warning, he started telling me about the surge of power a light bufb uses to warm up, and how he leaves his lights on so that he doesn't waste electricity turning them on and off. I've heard that insane notion before, but this guy launches satel- lites into orbit for a living. I was ab- solutely flabbergasted that an actual rocket scienttst believed an old wife s tale^like that, § Well, I asked him to explain, and ^ he told me that the filannent of a cold ^ light bulb had a resistance close to zero, and therefore was effectively a E short circuit when power was first ^ applied. I replied that, while that g might be true, the warm-up period is 6 so short that it couldn't possibly pull *S more current than even a second of ^ operation, let alone the minutes and possibly hours he was talking about. He disagreed, and, after all. he is an 14 engineer) So, forget the opinions. Here's an actual measurement. 1 stoked up my trusty Macintosh and set up my analog-to-digital converter to mea- sure the current of a 100-watt GE soft white bulb Cin my desk lamp) at 22.000 samples per second. Any- thing that was so short as to fall in between the sannples would cer- tainly not affect a power meter When first turned on. a 100-watt bulb pulls about 165 watts, but rapidly falls off to a nominal 100 watts in less than %o second. In fact, it falls to less than 150 watts in just ^60 second. That makes the average wattage for the first second only 1 03 watts, but by the end of the next second, the wattage has been stabilized at 100 watts for^eo of a second. My friend the rocket scientist told me in the iight-bulb aisle that he leaves his lights on to the tune of 100 watts per second to save 3 watts for one second. In other words, he wastes 30 times more power in each extra second he leaves his lights on than were used to start them up. One extra minute's operation would consume 1800 times the power to turn them on, and an hours would amount to a whopping 108.000 times the power to warm them up. No wonder it costs so much to run the space program! If I were to figure in the inertia and internal friction of the power meter, Tm sure I would find that it would undemead so short (and small) a change in power reducing even those 3'watts. I wonder how I could measure that*? By the way, the same friend once told me that if you leave a car bat- tery sitting on a concrete floor over- night it will go dead! But I've never actually checked on that. In Itght of all this. I have actually checked for the existence of satellites, and they afB up there — amazingi STEPHEN A. SCHLEICK Livonia, Mi IN HOT PURSUIT OF TV TRIVIA If Ephrim Zimbalist Jr did indeed sit on his chief's desk and make conference calls around the country in 1958, as alleged in the "Speaker Mate^' article (Radio-Elec- tronics, January 1992). then he did so in the company of Roscoe. Rex, and Gerald Lloyd Kookson III Thus, he was not in the role of of FBI agent Lewis Erskin, but in the role of chief private investigator Stuart Bailey on 77 Sunset Strip. The FBI aired its first episode on September 19. 1965, Im not a TV- trivia buff, but it would have been pretty difficult to stage chase scenes and traffic jams with about 500 identical 1965 Ford LTD s, as the director often did, when the program's sponsor was still making Edsels. "Kookie, lend me your comb!" Snap. snap. MICHAEL W, TOLAND Dover NH TRULY A TESLA COIL In fBSponse to the letter titled 'True Tesla Coil?" that appeared in the January issue. I vrould like to point out that the Solid-State Tesla Coil in question (Radio-Elec- tronics, September 1991) /s a true Tesla coil. I refer you to Tesla's lec* ture that was delivered before the Franklin Institute in February 1893, The text can be found in the book The Inventions, Researches, and Writings of Nikola Tesla by Thomas Commerford Martin Ct894X That book is available in repnnt On page 344. Fig. 184 shows a generatordriving two different coils. One coil looks like a so-called Oudin configuration, and the other coil is directly connected with a single wire. The Solid-State Tesla Coil works on exactly the same principle that Tesla used to describe that fig- ure! The generator in the diagram could, of course, be any source of alternating current. Tesla was lim* ited to mechanical generators and capacitive discharges as sources for his alternating currents. 1 called my Tesia co\\ "solid-state" because it produces the same results that TesIa s coil produced, using his methods but introducing solid-state electronics. Figures 180 and 181 from the same lecture also show his use of direct coupling. In fact, TesIa made many diagrams and wrote many de- scriptions on "open" circuits or those powered with "single wires." TesIa understood resonant phe- nomena very well and i doubt that one could say the same for Oudin. TesIa has priority on direct coup- ling — or any other kind of coup- ling — not Oudin. DUANEA. BYUUND HAMFEST ALERT? The Zero Beaters Amateur Radio Club will hold its 30th annua! ham- fest on Sunday July 19, 1992 at the Bernie H. Hillerman Park (Wash- ington Fairgrounds) in Washington. Missouri, from 6 AM to 3 PM. Theng will be a flea market C$4-a-space parking fee for the flea-market), seminars, dealer displays, non-ham displays, and refreshments, VE exams will be given on a walk-in basis starting at 10 AM; bring your original license and a photocopy. Parking and admission are free. Talk in: 147.240 and 44.900 repeaters. CRAIG BRUNE, NOMFD Hamfest Chairman Dutzow, MO FUSE FIX Some errors appeared in our Electronic Fuse article (Radio- Electronics. December, 1991). Pushbutton switch S3 and LED1 were shown incorrectly in Figures 1 and 2: S3 should normally be closed, and LED1 should be re- versed. Also, the left side of R9 in Fig. 2 should be connected to the positive side of C5. ASK R E continued from psge 12 huge sixty-cycle electromagnetic field — and there's nothing you can do about it, short of packing up and moving into a cave. The better your gear fs. the more sensitive its inputs are, and, unfor- tunately, the better suited it is to picking up induced sixty-cycle hum fnDm the power lines running in the walls of your apartment. Short of spending big bucks on transformers and other equipment, you should try shielding the cables in your system with aluminum foil. Just wrap them all individually and then try ground- ing the foil. Sometimes it works bet- ter if the foil is left unconnected to anything and other times it seems to be more effective when the foil is tied to a solid ground at one or both ends. Try both methods and see which one works out best for you. 1 know this doesn't seem very sci- entific but it usuafly works. If you find some other easy and inexpen- sive way to solve the problem. I'd like to hear from you since a lot of people have exactly the same trou- ble. A lot of folks would be mighty happy if you did. Remember what they say: Build a better mousetrap and you'll catch a better mouse. continued on page 78 Electronics Workbench The electronics lab in a computer Powerful software to build and simulate analog and digital circuits. ® Building md testing circuits is fast and easy with Electronics WorkJmich. Just dick-and^irag wth a mouse to add parts, run wires, and adjust instruments. The traces on the simulated instruments are the same as you'd get on real equipment Blecironia Workhendi really k an electronics fab in a computer. It's ideal for learning about electronics, experimenting, and prototyping circuits. ""Etecironics Workbench is pretty amazing^ -jerry P&umelk^PhM., iiifoWorU DOS Professional Version - $299 Madnlosh Version - $199 Eiedrontcs WoHthmich Includes: • Amtio^ Module wilh passive and acUve compnents including innsistor^, diodes, and op^amps; a fujiction generator^ an osdHoscope, a mulUmeterr and a Bode plotten • Digital Moduk with gates, flip-ftops, adders, a wofd genmtor, a log?c analy*zer, and a unique bgic converter and simpUfier (416) 361-0333 Interactive Image Technologies Ltd. 908 Niagara Falls Boulevard North Tofiawandaf M 14120 2060 Fax (416)368-5799 T fficfi irt in m dotUr?. OUtt viild in Lhe USA, xnd Ouadl OtCrf* Matinmh Version (i nior»diroflK only. AB tradflnarfcj i«.lh«' pttrptny oi thtJr rfspt cUve ovrten. r * tt CtRCLE 196 OH FREE INFORMATION CARD EQUIPMENT REPORTS Multidyne TS-8-MTS TV test-signal generator. 3 "c & lij 6 16 Track down TV v/deo and audio probiems quickly with the T5'8'MTS test- signal generator. anClE 10 ON wnEE INFOflUATION CARD Troubleshooting modem TVs and computer monitors is usually tricky business. Sometimes an experienced trou- bteshooter can diagnose problems without using any special test equipment, but usually he needs the right tools for the job. The right tool for repairing or aligning video equip- ment is the TS-8'MTS test-signal generator from Multidyne Elec- tronics. Inc. (12 Frost Creek Drive. Locust Valley. NY 11560. Phone 1-800-4-TV'TEST). It can generate eight different video test signals as well MIS stereo audio signals. The TS-8-MTS has a composite video output on a BNC connector as well as an RF audio/video output that is switch-selectable between channels 3 and 4. An RGB colorfaar output is available on a 9-pin D con- nector for testing computer monitors. Using a video-select pushbutton you can switch the BNC and RF outputs between eight dif* ferent video test patterns. Eight LED's indicate which pattern is se- lected. A switched horizontal or ver- tical trigger pulse is output on a BNC connector for triggering an os- cilloscope. All controls and outputs are b- cated on the front panel of the unit so it s easy to use on your test bench, Housed in a sturdy metal case, the unit measures about 12 x 6x3 inches. Video modes The video section of the TS-B* MTS produces 8 digitally generated test signals. When the unit is first powered up. it outputs an SMPTE colort^ar signal, which is split up, top to bottom, into three different gnDups of color bars. The test signal is used to check video gain, setup, hue* and saturation. Three black or gray bars on the bottom right of the screen make up the plage portion of the signal which is used to adjust the brightness of the picture. That is done by making the first two bars blend into each other If all three bars are visible, the pictune is too bright: if none of the three bars is visible, the picture is too dark. Next is the multiburst signal where the video display is a series of vertical black and white bars ranging from thick to thin, left to right. The signal is used to check the video frequency response of a TV or VCR. The signal itself con- tains six sine-wave bursts that all have the same amplitude when ini- tially generated. To check the fre- quency response of a TV, you would feed the signal into the TV and pick up the signal inside the set at a point just before it reaches the screen; the sine-wave bursts should still have the same amplitude when seen on an oscilloscope after the TV has processed the stgnaL The frequency response of a VCR can also be checked with this signal. All you do is record the signal on the VCR and check the output signal on an oscilloscope when playing back the tape. The Crosshatch, or convergence signal is next. The display is a grid with a dot in the center of each square. The signal is used to check and align the red, green, and blue color guns in a TV. When the grid- and-dot images from the three color guns are perfectly overiapped. the picture is fully converged. The grid can also be used to check vertical linearity. The horizontal bars should be equally spaced; crowding at ei- ther the top or bottom of the screen indicates a problem. The NTC7 signal, or pulse-and- bar mode shov^ vertical blocks and bars on the screen. The test signal is used to measure short-time, line time, and field-time luminance dis- tortions. The distortions can be seen on an oscilloscope as ringing, under-shoots, over-shoots, and tilt of various parts of the signal after it has been pnDcessed. The stair-step signal consists of five steps in luminance from 0 to 100 IRE which is seen on a video display as a gray scale of five ver- tical bars. (IRE is the picture bright- ness level: 0 is black and 100 is whiteJ The signal is used with an oscilloscope to measure luminance nonlinearities. The modulated stair-step signal is used to measure differential gain and phase. Differential gain is pres- ent when the chrcima or color gain is affected by the luminance or black and white gain. Differential phase is present when chroma, color phase, or tint are affected by the luminance or black and white gain. The mea- surement can only be made with a video vector scope having differen- tial gain and phase measuring ca- pabilities. The red- fie Id signal creates an en- tire video display of red to check for moire, color purity, and noise. The black burst signal can be used to measure color burst and setup am- plitude. Audio In addition to video signals, the TS-8-MTS can generate an MTS stereo audio signal. Audio is pres- ent at the RF output and a separate phono-plug output. The audio can continued on page 88 The new Tektronix 224 is as powerful as they come. And goes! 1 With this new 6D fAHi digital oscilloscope, Tektronix takes handheld performance to an even higher plane! The 224 packs more power per pound than any other pfodiict and — with ils on-board rechargeable batteries — goes wherever duly calls. With ils exclusive IsolatedChanner architecture, you can make two- channel floating measurements without the risk ol shock or damage to delicate electronics. Such standards as Tek^s sharp, bright CRT, rapid update rate and wide viewing angle make measuring tast and efficienl. And tt\e 224's familiar front panel and fully automatai features teep it simple. You gel advanced capabilities like video line triggering and 10 MSfe digitizing p^ channel lor excellent single-shot perlormance, plt^ tirrE- correlated single-shot waveforrns for w/ comparison. With CAT2flO software you can even control the 224 over phone lines from halfway round tts mt\6. Call 1-800-426-2200 Ext. 83 to get the full story. We ll show you more of &ie 224 — and ways it's giving bench performance wingsi Ctjpyrioht rO 1992, Taktroni^t, tnc. All ngtits rsservfd, Tektronix /^sl and Measuremont CIRCLE 92 ON FflEE INFORMATION CARD No other tramin[_ to troubleshooi computers Only NRI walks you through the step-by-step assembly of a powerful 386sx computer system you train with and keep — giving you the hands- on experience you need to work with, troubleshoot, and service today's most widely used computer systems. Only NRI gives you everything you need to start a money-making career, even a business of your own, in computer service. No doubl about it: The best way to Icam to service computers is to actually build a siateof4hc*art computer from the keyboard on up. Only NRI, the leader m career-building at homc clectn^nics uaining for more than 75 years, gives you that kind of practical, real-world computer servicing experience. Indeed* no other training — in school, im the job, anywhere — shows you how to troubleshoot and service computers like NRI. 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What s more, you now go on to install and test a powerful 40 meg IDli hard disk drive — today^s most*wanted computer periph- eral— included in your course to DIAGNOSTIC HARDWARE AND SOFTWARE R A C E R pIiiK-in UiaKitosiic card and QukkTccK mrni^ drivicn s<>ftwiire, botU fftjtn iHtra-Xp ^ivc yiKJ hoiiilvfjii cxpcrlcnLC willi tixtay s DISCOVERY LAB r4>mfi1c(c hrradhoarding >>^tm Circuits, dijunnst- ^dl^pillf fauUs LESSONS Clc^T, lllmllliEinJ K'XO build your undci^unding fif Ciiniputcn^ step by slt'p MONITOR lligii-reM>tulJiort. luinK^iiVt I r 1TL Eiuin^Hrlinjiiiic- RWHiitor with t\k and *wivcl OiOfTAL LOGIC PROBE SimptLTics analyzjng dtgiul circuit opcntkHi DlGfTAL MULTIMETER ProfraakwHl icM iosinmicnt for qukk and cftsy Eiiesurcmeni& SOFTWAflE Tr^ ^ith MS-DOS, CVW-BAMC. and papulaj- applit-aticift* MfrA-afr QujckTech QtiickTech dramaticuUy increase your com- puter s data stonge capacity' while giving you lightning- quick data access. But that*s not all! 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You'll use your Ultra-X Quickl cch diagnostic softT^^are to test the system KAM and such peripheral adapters as parallel printer ports, serial communications ports, video adapters, and floppy and hard disk drives. YouUl go on to use your R.A.C.E.R. diagnostic card, also fn>m 1 Iltra-X, to identify^ individual defective RAM chips, locate interfacing problems, imd pinpoint defective support chips. This ingenious diagnostic package is just one more way School of Electronics McCir.vvv Cts «h%ij4T nanga «Matui F^ngi *B«nch Tvpe «D«iaHo!{} «D«ift ^Fe) Ft^H^n aManual Range • CivKi VC* Ch*a wLth LCD FG«02 ■{152 kr To GP_103_. 1BV- \QA GP 235 L lev 1,0A 30V Ct.bA 2« 5} <5o*dStar Prcsclsion Co^Ltd TEL r3i ■ i ■ J ^ 1 ■ t FAX . tl T0> 9J 1 6227 handheld or hot-air deso- Iderlng tools. According to Air-Vac. all leads will be evenly heated — even on multilayer PC boards. This featufe eliminates the need for reheating and desolder- ing individual missed joints. The user of the PCBRM-t2 Is first in- CiRCLE IS ON FREE INFORMAirON CARD structed to select the prop- er "flow well" and match- ing hole-cleaning "hood" (corresponding to the lead pattern) before setting the temperature, flow rate, and cycle time. The PC board is then inserted into the unit s carrier arms with the com- ponent to be removed posi- tioned over the ffow welL When all solder joints are molten, the component can be lifted from the board and the holes can be cleaned of solder by a low- pressure air jet. A replace- ment component can be immediately inserted and soldered. Custom flow wells are available for se- lective tinning, soldering and desoldering of double- sided PC boards and sub- assemblies. The PCBRM-f2 solder reflow module is list priced at $7300 —Air-Vac Engi- neering Company, Inc.. 100 Gulf Street, Milford, CT 064 60; Phone: 203*874-2541 ; Fax; 203-783' 1383. 8- OR 16-BIT VGA CARD. JDR Microdevices' VGA card should attract com- puter owners planning to CIRCLE mOH FBEE BJFOnUATTOH CAflO upgrade their present sys- tems rn the future. They wil! be pleased to know that this VGA card can be transferred to a faster sys* tems- Capable of operating in efther 8- or 16-bit nnodes. the card can upgrade IBM compatible computers based on 8088 MPU as well as those with the 286. 386, and 486 MPU s. Ac- cording to JDR Micro- devices, advanced ASIC technology permitted them to minimize the number on- board components while providing the features found only in more expen- sive cards. This VGA card supports video monitor resolutions of 800 x 600 and 640 x 480 in 16 col- ors, and 320 x 200 in 256 CIRCLE 19 ON FREE INFORMATION CARD colors. It provides auto- mode switching for VGA. EGA, CGA. MDA. and HGC. and it supports both analog and multisync monitors. Software drivers for Windows 3.0, Auto- CAD, Lotus 1-2-3, GEM, Ventura Publisher, and other programs are in- cluded in the purchase price. The VGA Card costs $49 95.— JDR Micro- devices. 2233 Samaritan Drive. San Jose, CA 95124; Phone: 800-538-5003; Fax: 408-559-0250. ONE-PIECE TEST CENTER. Four of the most commonly used pieces of test equip- ment are combined in the Tenma Test Center. Model 72-710. The test center contains a 2-MHz sweep function generator, a 100- MHz frequency counter, a triple-output power supply, and a full-function auto- ranging digital multimeter. The frequency counter can stand in as a precision dis- play for the sweep gener- CmCLl 20 ON FREE INFORMATION CARD ator or it can be a stand- alone frequency counter The power supply has three outputs. The first output provides variable voltage and current CO to 5 volts DC and 0 to 0.5 annps). It has a three-digit LCD display that can be switched for voltage or current readout. The second and third outputs have fixed voltages of 5 volts DC at 2 amps and 15 volts DC at 1 amp. respec- tively. The Modef 72-710 has a one-year limited war- ranty and the purchase price includes test leads and an owner's manual The Tesf Center 72-7f0 is list priced at $399.99.— MCM Electronics, 650 Con- gnsss Park Drive, Center- ville, OH 45459-4072; Tel: 800-543-4330. SURFACE-MOUNT INDUC- TORS, These miniature in- ductors are designed for automatic surface-mount assembly. The RL25t5 Se- ries inductors from Renco Electronics Feature molded plastic packages. Said to be impervious to moisture, they are suitable for solder- ing with either vapor-phase or infrared soldering sys- tems. The series includes 35 standard values ranging from 0.15 \iH to tOO jjlH with DC current ratings of 70 to 610 miHiamps. These i-if=imEi3 instruments Top engineering needs top equipment Our line of high quality measuring instruments offers a full range of outstanding features and unbeata- ble price/performance standards. 1939 Plaza Real 20 Lumber Road BLDG. # 2 OCEANSIDE. CA 92056 ROSLYN, NEW YORK 11576 Phone 1619) 630-4080 Phone (5161 484-7121 Telefax (619J 630-6507 Telefax (516) 404-7170 CmCL£ 200 ON Fn£E INFORMATlOrt CAflO CIRCLE 21 Orsf FREE INFORMATION CARD inductors can be used as filters and as components in filter networks. The oper- ating temperature range of the inductors is - 2b°C to + 80=C. The RL2515 inductors can be supplied on tape and feel or in bulk quan- tities. They are priced at 25 cents each in 2500-piece quantittBs^ — ^Renco EIbc- tronics Inc., 60 Jefryn Blvd, East, DeerP^rk, NY 11729: Phone: 516'586'5566. PC-BUS POWER MONITOR CARD. Intended for com* puter-service personnel. Winteks PC-Bus Power Monitor Card can detect power disturbances and identify substandard power supplies in PC» AT. and EISA computers. Pack* CIRClf 22 ON FREE INFORMATION CARD aged on an ISA short card, the power monitor can be plugged into an expansion slot. It then checks to con- firm that all four supplies are within specifications, delects the presence of glitches or dropouts, and displays the tnformation on an LED display. Many inter- mittent operation problems that appear to be caused by memory or disk faults are actualty power supply problems. The PC-Bus Power Monitor Card is a handy tool for identifying or ruling out power-related pn^blems in the field. Ac- cording ioWintek, the Power Monitor Card is per- mits faster and easier power supply checking than a digital voltmeter or oscilloscope, especially when the faults are inter- mittent. By detecting a de- teriorating power supply, system errors and cata- strophic failures can be avoided. The standard card pro- vides a real-lime indication of power quality and its memory stores momentary out-of-tolerance events. The enhanced version of the card includes an audi- ble alarm and separate monitonng circuits to spot intermittent trouble with the system clock and dy- namic-memory refresh sig- nal The basic and enhanced PC-Bus Power Monitor Cards cost $195 and $249. respectively— Win- teck Corporation, 1801 South Street. Lafayette. IN 47904-2993; Phone: 800'742'6809: Fax: 317-448^4823- l&Q MODULATOR. This modulator is intended for radar and communications applications. Mini-Circuits' MfQA'TOML t&Q Modu- lator offer s -38dBc car- rier and sideband rejection. Its third- harmonic supprBS* sion is - 48dBc and its fifth harmonic rejection is "64dBc. This SO-ohm de- vice operates over 66 to 73 MHz frequency range in both local oscillator and RF applications. It offers 10±1dBm local oscillator power over a -55 to lOO'^C temperature span. CIRCLE 23 ON FREE INFORMATION CARD Conversion loss is spec- ified at 5.1 dB. The modu- lator is housed in an EMI- shielded case that mea- sures 0 8 X 0.31 xO.4 inch. The MpA'ZOML modu- lator is priced at $49,95 in quantities of 1 to 9. — Mini- Circuits, PO. Box 350166, Brooklyn, NY 11235; Phone: 718-934-4500: Fax: 7l8-332'466t. ANTI-THEFT VHF/UHF AN- TENNA. A prominent exler nal antenna on an auto- mobile alerts thieves to the presence of expensive transceiver equipment within your car and attracts vandals. 7?)eStea/f/i anten- na frum ;*Com is an inter- nal antenna that disguises the presence of expensive transceivers in your car and offers no temptations for roving vandals. The anten- na is made as a 0.003 inch thick etched copper ser- pentine on a gray shaded polymide substrate that measures 3.5 X 3.5 inches. CIRCLE 24 ON EREE INFORAUTION CARD Its gray color permits it to blend almost invisibly be- hind the anti-glare band on the upper surface of an au- tomobile windshield. Ac- cording to /•Com. this inside-mounted antenna does not reduce trans* cerver performance. The etched'copper antenna is multipolarized to provide high gain regardless of sig* nal pol3ri2ation. That fea* ture ensures good recep- tion in rural as well as urban locations, and it provides a steady signal in your car when it is moving. Because 7??e Stealth antenna could pass for a decal, it is also available with an optional printed warning symbol as a further deterrent to thiev- es. The antenna is said to have a fow standing^wave ratio over its specified fre- quency band, and it does not require adjustment or tuning. The Stealth is adheres to the inside of a windshield with the adhesive on its backing: no drilling, clips or suction cups are neces- sary. Because the antenna is mounted inside a vehicle, it is protected from the ele- ments and need not be re- moved or retracted when entering garages with low- clearance entrances or car washes. Standard and high- power models of The Stealth are available for mid-band operation at 146, 220. and 440 MHz. Stan- dard models ane rated for 50 watts of input power, and high-power models are rated for 1 10 watts. Sixteen feet of RG 58/U coaxial ca- ble is included with each antenna. The standard Stealth An- tenna is priced at $59.95 and the high-power version is priced at $69.95.— jeCom. Box 194, Ben Lo- mand. CA 95005: Tel: 408-335-9120: Fax; 408^335-9121. R-E sSSfFunctionT ave. mported instj:umen Ultravariable Pulse Generator '0.5 to 5MHz •Run, Triggered, Gate, Singie-Shot •Independent width and space controls •Variable 50i2 output Model 4001 SI 99.95 Audio/Sv;eep Generator •Slne/SquareH'fiangle •1Hz to 100kHz •Variable DC offset •Sweepable 100:1 Model 2001 SI 78.50 2MHz Sweep Function Generator •0,2Hzto2[i/IHz V. • Duty-cycle, symmetry controls ^ •50£} output ^\ •VCO input ^ Model 2002 S219.95 Digitally Synthesized Generator ^ | ^ •DC to 1.6MHz ^^'^ * * •Trigger, Sweep, Burst Hop and Gate modes • Inlemaf/Extema! Sweep ^ ^ • Sine, Square, Triangle, Ramps •Optional RS-485 communications port •16 programmable memories Model 2003 S499.95 Compare the specifications and the prices of these four instruments with the competition. Then compare the labels. Global's say "Proudly Made in U.S.A.". Designed and manufactured in our Connecticut factory with the value and quality that Global is known for. The competitors, they look alike because they are. Different names on the front. The same label on the back. "Made in Taiwan". With Global you'll get a Good Buy, and can say Good-bye to imports. ^Can't Wait? Call...1 -800-572-1 028 GLOBAL SPECIALTIES 70 Fulton Terrace New Haven, CT 06512 - - FAX 468H}060 Spccefcalnfiii subject ta cKange ^tr>mit f\otc£r m 27 anCLE ^M ON FREE W FORMATION CARD NEW LIT Use The Free Information Card for fast response. OS I o 2a BOB GROSSBLATT'S GUIDE TO CREATIVE CIRCUIT DE- SIGN; by Robert Grossblatl TAB Books, Division of McGraw-Hill Inc., Blue Ridge Summit, PA 17294-0850; Phone: 1-800-822-8138; S17.95. If you read Radio-Elec* Ironies regularly, then you're familiar with Bob Grossblatfs columns and occasional feature stories. If you write to Radio* Electronics occasionally to request help with circuit- design problems, then you're one of the people credited with providing in* spiration for this book. CREATIVE CIRCUIT DESIGN CIRCLE 40 ON FRte INFORMATION CARD In its pages, Bob Grossbfatt explains how to minimize your chances of running into such glitches- — and how to work your way out of those that do arise — by following his common-sense approach to the design process. Working under the princi* pte that the primary cause of such problems is not lack of knowledge but a poor design methods he presents a systematic ap- proach that can be followed when prototyping any elec- tronic circuit. To take your idea from concept to work- ing project, the author ex- plains, you must think it through and outline it in a notebook before you get into detailed planning (list* ing design criteria, choos- ing components, calculate component values, identi- fying alternatives, and set- ting operating parameters). Then you're ready to create block diag rams for your de- sign. To keep from getting bogged down along the way, he continually empha- sizes the importance of keeping an open mind about making changes in theoriginal design, and per- severing until you have a finished product, even if it s not as perfect as you would like. Construction details for dozens of basic circuit "modules*' that can be combined to form more complex — and quite use- ful — projects are pre- sented, including a multi- voltage bench power sup- ply, an audio preamplifier and amplifier, a fully buff- ered, 64 K RAM system, a programmable home-con- trol center, a VCR sync sta- bilizer a battery back-up circuit with automatic switch-over, and a micro- processor-based waveform generator. Information on where to find components and technical literature, and how to set up an effi- cient workbench is in- cluded. To keep things from getting too heavy, troubleshooting hints, de- sign tips and tricks^ and Bob Grossblatt*s own adages are included. Com- ments tike "First make it work, then make it neat/' 'People make more nnis* takes than electrons." and "Versatility breeds com- plexity" are liberally sprin- kled throughout the text. HF/IF SIGNAL PROCESSING HANDBOOK; fmm Mmi-Cir- cuits, P,0, Box 350166. Brooklyn. NY 11235; Phone: 718-934-4500; Fax: 718-332-4661; free. Aimed at design engi- neers, this 718-page hand- book is loaded with prac- tical articles, answers to frequently asked ques- tions, definitions of terms* convenient selection guides, and handy con- version charts. The com- prehensive reference also includes hundreds of pages of fully detailed. CIRCLE 39 ON FREE INFORMATION CARD computer-automated per- formance data (CARD) specifications, and perfor- mance curves to eliminate guesswork during the de* sign pn^cess. Components covered include frequency mixers, power splitter/ combiners, amplifiers, l&O modulators and demod* ulators. phase detectors. RF transformers, filters, switches, directional cou- piers, and attenuators, HAWK PROGRAMMABLE ON-OFF CONTROLLERS/IN- DICATORS; from Simpson Electric Company, 853 Dun- dee Avenue, Elgin, IL 60120-3090; Phone: 708*697-2260; Fax: 708-697-2272. Simpson's recently intro- duced Hawk series of dig- ital on-off controllers and indicators is featured in this CIRCLE 38 ON FR£E INF0R.KUT10N CARD 32-page, full-color catalog. Designed for start, stop, or limit control of a wide range of process variables, the controllers have broad ap- plications in electrical, chemical, petrochemical, and other process indus- tries. Models are available for AC and DC voltage cur- rent. 4-20-mA DC. 1-5V DC resistance. S-wine po- tentiometer, frequency, and tachometer Crpm) in- puts. Also featured are models for 2-. 3-, or 4-wrne RID inputs and J. K. R, or S thermocouples. Each Hawk series model is neat- ly packaged in a compact % DIN case. The catalog provides descriptions, technical notes, complete specifications, a glossary of terms, available ac- cessories, and ordering in- formation. AUTOCAD FOR ELEC- TRONICS; A TUTORIAL; hy Thomas Tumilty. Prentice Halt, Englewood Cliffs. NJ 07632; Phone: 201-592-2000; $43.00. By demonstrating the step*by-step development of manufacturing drawings for a quad power supply and a multiwave function generator, this book — and the included diskette — show readers how to de- sign electronics products 48HOUR ELENCO & HITACHI PRODUCTS c.Sr'Z'A^ AT DISCOUNT PRICES .-woTSiu^^, nitacni k5u series (P0rta*>(» Reat titne Dtg^i^l Storage QscinDS£tip#$) VC-6023 - 20MK2, 20MS/S Si .695 VC-602* - S0MH2, 20MS/S Si .995 VC'6025 ' 50MHI. SOMS^s S2.195 CaD ' Can ■ S0MH2, 20MS/S 50MHI. SOMS^S VC-6045 ■ t OOMK;. 40MS/S _ VC-SMS ' tOOMHz. TOOMS/s SPECIAL BUY V*212 ' 20MHz Scope $409 ni«astir»ni«nts Thosa scofies eubffl fnor@ TOCufal«. SMCft rufKtxm^ M tiaidcopy via a pmner iniifiace ancr 25MHz Elenco Oscilloscope Hifachi Portoble Scopes DC to SOWlHi. 2-Chcinnel, DC olfie! (unc- lioo. Alternate mogfiffief fuficiion V 525 - CRT Readout. Curs&r Mcas S995 V-S23 - Delajred Sweop S975 V 522 ' Basic Model S875 V-422 - 40MH: S775 V-223 ■ 20MH3 delayed swoep, $695 V-222 ■ 20MH: deluxe $Q25 HITACHI COMPACT SERIES SCOPES Tra s&fw p'ovoes many n«w Sunctiom juct as CAT HeadcuL O^w m<«ui»ni»ig^pA-toeSrt06SA«6SJg,l^ outincy C!f rv*T0S5}. SwMSCfli* Aitfonnm, D»ti|>d V-660 - fiOMHz. DuaT Trace S1J49 V-665A- 60MH2, DT. *^/cyr£or SK345 V'1060- lOOMHi. Dual Trace SK395 V'1065A ^ lOOMHi, DT. w/cursor Si .649 V-108S * lOOMHi. OT. w/cofsqr Si. 995 V^noOA - lOOMHz. Quad Tfsce S2.t95 V-ttSD^ 150MH2. Quad Trace S2.695 $349 S-1325 • Dual Traces • imV Sensitivity • 6'CRT - X-y Operation * TV Sync • (2) 1 X, 1 0x Probes included Al wPOfm irvctuds ptdbQ^, sclifirTvatcs. optFSiof s manual an iCQpn Cati ty irrrrfl tew conplietfl ^pocrfcalicns on ihffsa met Elenco 40MHz Dual Trace Goodio 5495 ^""^ ll340 • High luminance 6" CRT » imv Sonsitiviiy * 10KV Acceleration Voiiage • 9ns flrso Time • X-Y Oporation • Includes (2) 1x. IOk Probes 3 Y^at {2 yrs few Eienco soop*s} wcfW wido warranty C3n p^ns & E^t. Many acMSMfrtS avaiiabia lor all Hetacnj many Gi+^f fine osoiiascopes ijt^ lOx Scupo Probes: P-1 45MHI »17,95. P-2 lOOMHi S21.95 PRICE BREAKTHRU 20MHz DigitQt Storog^ Oscilloscope *Atiii1[50''Qi[;i!al Scope • word pfif channel momory DS203 * \ OMS/s sam p I i rata * Slato of an Technology $ 775 • Includes probes 60 MHz Delay Sweep $775 Digitoi Copocttonce Meter flSa CM-tSSOB $58.95 Zff B cortrot Casr Big l-Oi5;3iir Ojgitql LCR Meter SI 25 0'15V^ 1A {or4ia 30V @ 1 A} and IV # AM/FM Transistor Radio Kit with Training Course McdClAHFMlOS $26.95 U Trar^stsEors « S Diodv^i True RMS 4 11 Digit Multlmetef M-700T $135 DC Accuracy mm Freq Cfl^uRitfr Da!ii Hold GF-dQ1& Function Generator with Freq, Counter $249 TSane, Square. Tniinipiic- PuFie. Ramp. .2 loSMH: Frflq Couniur 1 ■ tOEi^H: GF-aOIS wilhoul Fieq. Meter $179 Function Genera ior BIOS S28,95 *;iv*s horn IHf 10 iMHi AM of FM czpaaiiity Leorn to Build and Program Computers with this Kit Mocfei UM-aooo Wide Band Signal Generators $129.00 IAoq-Mmw ItMW NClW TOUIO RAM, ttmLtf ifWtMnn language K IfiU PC . SG'SOOO $129 riefl or llWt Va*'a£* t^F c-tput 80^9500 w' Oigilal Otaptay £ 1 SO MHi buFIMn Counler S243 LASER KITS Build ^QLjr Qwrt laser. Tins great kil mciudcs aiJ parts nocdod lo bir.'d a class 'I \^^C't Sale to use, ouipyt isuncj&f one mrHiwail. Kit includes a ne*f He-Ne i 12S dia i 5 75" Eong laser luDo, Cemes ^lEh bmlding mstrudic^ns. scnomaiic and all parts Model LK-1 $79.95 Specifications LK-i: 1 np ut volt age 1 2 VOC <§> 1 25 amp OutpLJl voUage 2 3KV @ 3 4 5MA Trigger voliag© 6 SKV Las^r powct t rrullrwaU Las^ tube ty|>e rt&Uum - n&m Laser JutJo sue 1 1 25" dia x S.7S" long Mirror & Motor Kit TtiisuiwjueiBi j^omsyoytopri^e^ ^se-^caiifi^s on ineceifngflmais Vowciwise itw failvni liy vv|«g tne speed oA re motofs Tne ka tsffm vamfim wii 2 iwMoii, 2 tm stflaot mors, 2 fmriar t)i^^ ModeUM-1 $19.95 WE WILL NOT BE UNDERSOLD UPS SHIPPIf^G: 4S STATES 5S IL RES 7.S% TAX ($3 min $10 max) OTHERS CALL C&S SALES INC. 1245 ROSEWOOO. D££RFIELO, IL 60015 FAX: 70S^520*(I085 • [708) 541^0710 15 DAY IVIONEY BACK GUARANTEE 2 YEAR WARRANTY WRITE FOR FREE CATALOG Pa Cn SUBJECT C^'ANCE 29 CIRCLE 1D9 OK FREE tHFORMATION CAf^O GOLD COMDITIONER St PRESERVATIVE Solid 6o/rf Profedion forAudiOf Video & Cmpufer tquipment • Protects GoM Surfaces & Base Metals! • Improves Conductivity! • Reduces Intermittent Corinectton Failures! • Foims Protective Coating^ « Reduces Wear & At^rasKHi! - Reduces Arciftg & R¥\l LABOflATOR:El'i 16744 West Bei^iardo Dr. Rancho SemardQ. CA 92127 1904 (619}45L-17B9 FAX: (6191 451-2799 CtRCLE 50 OH FREE INFORUATlOfI CARD QUALITY TV & VCR PARTS SEMICOND U CTO R S 2Sai72B STKQOBO Sl6.9Sea 250869 lo/up $i,99ea STK4273 Sa95ea(10mln) 2SDl39a 2SD1426 STR30120 $3.95fla REPLACEMENT FLYBACKS 154-074E GOLDSTAR $19.95ea 154-mOA GOLDSTAR $19.95ea FCC1415AL SAMSUNG $19.95ea 3214003 EMERSON $Z4,50ea TLF14423F PANASONIC $29.95ea ILF14530F PANASONIC S29.96ea 2434391 HITACHI $34.^ 164113 RCA S3.50ea(10min) NPLY0111GEZZ SHARP S10.95ea NPLYOOOeCEZZ REPLACEMErJT SZ^a l43'CW2tm)iM00 REPUCEJAENT S4.^a POPULAR PARTS S26A TRIPLER $a95ea 4*1164-031600 SANYO RF Sl7.95ea MODULATOR 100W50V RADIAL 20/for$10.00 47W'250V RADIAL 10/for$5.50 lOOOM.^OOV SNAP'IN 5/for$12.50 47IVl'50V RADIAL 10/for$4,50 bSaiEiFaROMICs' 975JAYMOR ROAD SOUTHAMPTON PA 18966 CALLTOLLFREE 1^00*628*1118 FAX# 215*364-8554 'mm CIRCLE 37 ON FREE INFORMATION CARD from scratch using Auto- CAD. The text also demon- strates how a computer system works in the course of the product s de- velopment, how Auto- CAD's commands are used, the technique for transfating a hand-drawn sketch into a complete schematic/wiring diagram* and how to lay out a simple printed-crrcuit board. It also covers mechanical and electrical assembly meth- ods, why components must be oriented m specif- ic ways, universal drawing standards, etc. Practice exercises permit readers to improve their skills in di- mensioning, text styies, and isometnc and thme di- mensional drawing. Con- centrating on the baste commands that am used in all versions of AutoCAD, the book provids a knowl- edge of the fundamental concepts of computer- aided design and a founda- tion in AutoCAD from which the reader can go on to master more complex commands. BSOFT SOFTWARE ENGI- NEERING TOOLS CATALOG #5; from BSOFT Software Inc., 444 Coltoo Road, Co- lumbus, OH 43207-3902; Phone: 614-491'0832; Fax: 614-497-9971; free. BSOFTs latest catalog offers low-cost, stand- alone engineering pro- grams and hardware de- signed for engineers, tech- nicians, and hobbyists using IBM*PCs or com- patibles. Included are pro- grams for drawing sche- matics, simulating logic- contnDl circuits* FFT analy* sis, and circuit analysts. CAD programs for struc- tural analysis, designing electronic circuits, and PC- board layout are also of- fered, along with PC bus board products for control and data acquisition. The 26-page booklet contains CIRCLE 36 ON FREE INFORMATION CARD product descriptions* dis- play printouts of sche- matics and waveforms, and ordering information. SURFACE MOUNT &IC TEST ACCESSORIES; from ITT Pomona ElectronlGS, 1500 East Ninth Street, RO. Box 2767, Pomona, CA 91769; Plione: 714-469-2900; Fax: 714^629-3317; free. Highlighted in this 14- page catalog are Pomona s complete lines of SMT/IC test accessories, kits* and .A p * CIRCLE 3S ON FREE INFORMATION CARD probe sets. The booklet features DIP/SOIC* PLCC. QFR and SMD MicnDtest clips and assemblies, mini- ature pincer and hooked test clips, standard hooked test clips, alligator test clips, coax cable assem- blies, test lead kits, adapt- ers, breakouts, and inter- faces. Fifteen major prod* uct categories are pre- sented. f|«C CIRCLE S9 ON FREE INFORMATION CARD Electronics Paperback Books GREAT PAPERBACKS AT SPECIAL PRICES BP24e-TEST EQUIPlytENT CON- STRUCTIOM oxponsive, but ax^ tromoly uselut test cqLiipmont. AF Gen, Toat Bench Afnpl, Au- dio Mity-rtjtlmeter. Tran- ststof Tester and sji BP26r— HOW TO use OSCIILO^ SCOPES AND OTMEfl TEST EQUIP- MENT ..... Ma^^- toring I ho oscrlloscopt; is notroaiiy too dtflcult This book OMipildins a^ll Iho standard controls and luncttons Olher e , tioirmm coveted indude wor tj t cessors. speiimg dvclaefS. graph »C3 pro^rains. desklop pubishing. daiatuses, spiBadsheets and ut^ BPa47-MORE ADVANCED MIDI PflOJECTS_S£w9SJ Cw^ts mfMod ate a MiDt indicator. THRU box. meftfc uni. code genei atot. peas«d alarms and an unuwil fcym of t^ tmmik. intnidet de4eciot i I BP23S— POWER SELECTOR GUIDE SI 0.00. Complela guide lo sefmconduc- tof power devices Moce than tlXKl power handling devices are iinctuiled They are 1iit>ulaled in alpha-numeric set^uoncy. by ischntoal specs Includes power diodes. Thyristors, Tnacs. Power Transistors arKl FETs I ' 8 P2U— TRANSISTOR SELECTOR GUIDE...>Hl10m Companion volume to BP2^ Book covers more than 1400 JEOEC. JIS. and brand-specitic devices Also oonla^B itstcig by case type, a^ etectiiorHC parameters Inchjdes Darisng^ iraniisiors. hh^-'M0ita9e devices, hfgtvcurrenf dewes. Nqh pCNwef devices — iWtt-UJlTRlX BOARD PROJECTS SS.SO. H« are 20 usefi^ cnuds mat can be b&Mn on a rrsni -m^% boarc !ti^ is pusi 24 holes try ten GO<3per4oil i&ipS BP 11 7— PRACTICAL ELECT RONtC BUILDING BLOCKS— Book n,...IS7S. QsoiyAors. Ttfne#3. Noise Gefter ators. Rectif»atii. Comparators, Triggers anti mm ] BPIM^NTRO TO $9000 ASSEMBLY LANGUAGE (6.^. 6S000 is a ijreat new b^eed of micropfocessof Program rrur^g m assemtUy t^ngua^e increases l^he running peed ol you^ programs Here S wti^it you rieed lO know BP173_ELECTR0NIC CIRCUITS FOR THE COMPUTER CONTROL OF ROBOTS ^...^ 57.50. Dain ar^ dfcuiIs tor inlorlacmg the compute^ to thit* robot s motofS and sensors □ BP239— GETTING THE MOST Fm>U YOUR bases o* ana^ and dtgstal rmeters Methods ot transistors. Uiynslors, resistors, capa^ots and oiher $5.*5,CowrB mtng includes and pa&srve devices. n BP97— IC PROJECTS FOR B£G1NNERS..,.JSJ<}. Power S^ipfios, ratte ar^a audto cvruits,. oso&jdors> brnefs, swiiicl>^. and more. ltyDucantaeasoidenng«on you can bu]^ devces. □ eP37— 50 PROJECTS USING RELAYS, SCR S A TRTACS.....S5.50 Budd pn- onty indoors. 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BP2SS— INTERNATIONAL RADIO STATIONS GUIDE Provides tho casual hstened, .im.iltjuT radio DXer and the profcssHinal radio morutor virjlhan ei5fntial leference work desi'gned to 1 1 Tir >■ rr H.or arouml than qvor more ELECTRONIC HCHNOLOGY lOOAY INC. PO- Box 240, Massapequa Parit, HY 11762-0240 SHIPPING CHARGES IN USA AND CANADA Address . -State . RE692 SO m to S5 00 S5 01 toSlODO.. S10,01 10 30.00. S20.01 10 30.00 . . S30.01 to 40,00 . , S40 01 tc 50.00 . , S50-01 ar\d abo^e , 52 50 saso .S4.50 .55.50 .$6,50 .S8.00 SORRY No orders accepted outside ol USA 5 Canada Total pride of merthano^sc Stitppmg (see ctisrt) $mmi Sales Tax (NVSonty) . Total Encloseil Number of books ordered n All pavmenis must be in U.S. funds A C K THE PARTS Mlcromlnl Toggle Swiiehes. Retr- a&ility at tow cost Rated 3 A at ! 25 VAC. Vi-'-dm. slem. SPST. *274.624 . , 2.39 SPOT. #274-525 - 2.39 DPOT. *274-626 in f1) TO*220 Heat Sink. Idoal far PC boatd use #276-1 B9c (3)i TOO Mounting Hardwifi^ Com- p[m k\l. #275-1371 99« TO -220 Wtg. Kit. *276*1373 fiK mum h«at tTanstei: #276-1372 1.59 Try Our Exclusive Postage-Free Parts "Hotline" Your Radio Shack store stocks ovor IQOO tlecironlc components, ana another 15,000 Items am available ia&t irom our Specfai-Ofder warehouse. Selicllon incltidoi. ICs, iransistors and diodes, lubes, cryslals, phono cartridges and styti, aU aorifi of accessories, SAMS ' service manuals ^irid MUCH morQ. Vou pay no pos!ag&— we send your order direct to your nearby Radio Shnck {%) Portable Shortwave Antenna. DX grabber* Clips to portable's rod an^ renna 23 ft w^re (^rernfim siores on pockei-SJze reel j273-1374 . . 8. 95 (2) Dial Cofd RepatT Kit. Radio Shack exclusive? Inciudes six feel of High^ strength tJu^ cortJ and three tensior^ springs 2 74 -435 . 99C (3) 3" BrusHle^ 12V0C Fan. Exclusive^ Bmshless design and DC opefdtiofi make it a great chokre for cooiifig moD'te eiiu^pmetit and orcwils that are sensitTve to hum ot noise. 27 CFM a-rftow. * 373 '243 . . . 14.95 (4> UL*(lecoofli2«d Pow«f TranafoTfner, Exdiisiv^t 120VAC prjmary Center-tapped secondary provides 12VAC at 1 2A '273-1352 , . . 5,99 (1) DoublO'Shielded, 4 Conduc* tor Cable. For da (a or audio T?ie best? 30 n •278-777 7.95 (2} CoMed Mme Cable. Replace CB. ham. manne radio cords, 4 cor^ Ft. BNC-t&-BHa «27B-9&4.S.»f rC Inserter/Extractor Kit. Why risk bending of breaking pins on expensive chips? This kit makes il easy to install and remove any DIP - siyfe IC from 6 10 40 pins, Both tools are groundable to prevent siatac ■zaps". #276*1561 6.95 UL-Llated DVM. f^icronta' makes electronics testing a snap! Autoranging, Vz** LCD digils^ bar graph to spot peaks, data hold lo freeze display, continuity sounder, diode^check. #22-ia6 69.9S PC/XT Experimenter's Circuit Card. Tnis premium-quality prototyping board lits a computer's XT axpansion bus connector Features durabte epoxy glass construction and plated-lhrough holes on standard 0.100" centers. Accepts 0-sub connector sliown at right. 3''/BXlOVt»jx Via". #276-1598 , , 29 J5 Right^Angle D-Sub 25 Female Connector. Ideal for use with PC/ XT circuit card at lelt. Radio Shack also slocl^s a big selection of D-sub and lDC4ype connectors for com- puter hookups. #2764504 . . 2.49 Sine* 1971 Radio Shack h»i Oevn 1h« piflce to obtain up-lD-d«ti electronic parts ^^PSBdHMsB M ^^Sm^^mK ^tmij^g #0^^ ai well as quality toois/lftit equipment and accessor >e?ftnowpnpn.Ne.ij1y 7000 ^ ■H^n^SvrV »fVC£ WZT locallcjo* Are to f#rv* r «Hi - NO BODY C Oil PARES M mm^Sl^Tm^^i Pros IBP; u^anc^mqJltt» Stt» titm titan ^ldo^tMp^m^^^ Q? SPKR1 SI FIG. 5— PARTS-PLACEMENT DIAGRAM, Install LED3 and LED4 bent forward like headlights. MECHANICAL PARTS LIST • Metal chassis plate> approx. 3!^ inches wide (after the sides are benl up at W angles) x 3V2 inches tong, drilled to accommodate all other hardware • Two DC motors with shaft pulleys • Two front wheels (the kit uses two plastic knobs, V/i-inch outside diameter, with V4*inch shaft hole) • Two nylon or metal wheel sleeves. V^- inch outside diameter, Vfe-inch inside di- ameter, ^i/ie-tnch long • Two nyfon bushings, ^/a-inch outside diameter, y4-inch inside diameter. Vs- inch thick • Two 1-inch wheel screws with a nut and washer for each • One %-inch diameter roller bat! with hole drilled through the diameter • One roller-ball axle screw with two nuts and two washers • One ^i/i6-inch threaded hex standoff for the roller-bail assembly, cross-driNed on the bottom end • One mounting screw for roller-ball standoff • Two spring- wire antennas'feelers • Two antenna posts • Two iyi6^lnch threaded tiex standoffs and mounting screws for the PC board • Rubber pads and adhesive- backed fell for the two battery holders • Two rubber bands Note: The following Items are avail- able from The Electronic Goldmine, PO Box 5408, Scottsdale, AZ 85261 (602) 451-9495: (Add $3.50 shipping/ handltng) • Complete robot kit (C6466, bat- teries not lnclyded>—$39J5 • PC board only— $10.00 band stays in place. If the rubber band comes off you must align the wheel by bending the chassis slightly. Run the motor again to see if the rubber band stays on. If it stays on, reverse the batter>^ leads and check it again— you may have to readjust the wheel. (Never bend the chassis where the motors are attached and do not put any stress on the motors as they may come lose from their mounting,) When you finish aligning the right wheel, repeat the process for the left wheel. Two metal standoffs are in- stalled on top of the chassis using bolts and washers through the bottom of the chas- sis. The bolts go up through the chassis, through the standoffs, through the PC board, and the board held down with the nuts as shown. But first we have to build the PC board. Electronic assembly Assemble the circuit board as shown in Fig. 5. Watch the po- larity of the IC's, electrolytic ca- pacitors, and diodes. Note that the leads of LED3 and LED4 should be bent at 90'' angles so that they look Hke headlights when mounted on the board. Us a good idea to insulate the exposed portions of the head- light LED's, Install SPKRl as shown. DO NOT attempt to re- move the capacitor soldered across the speaker terminals; the leads of the capacitor are used to connect the speaker to the board. Now install feeler wires as shown in Fig. 6. Each feeler is made from a length of spring wire, bent as shown in Fig. 6. Fit the straight portion of the left feeler wire at the point ^ shown until it is flush with the g board. Bend the other end S around and insert it into the .f§ other hole as shown and solder ^ that end. Repeat those steps for §^ the right feeler wire. m Now make two feeler posts by S bending wire as shown in Fig. 6. | After bending, solder the posts g to the board in place over the feelers. Adjust the straight part of each feeler wire so that its centered under the post. Mak- 37 ing sure the feeler is not touch- ing the post, soJdcr the straight end of the feeler to the board. The feelers must not touch any part of the posts after they re soldered in place; reheat the so!* der If necessary to reposition the feelers. Check the operation of the feeler by pushing on the circular part^ — the straight part of the feeler should hit the post. Figure 7 shows the finished robot. Solder the battery-holder wires and the motor wires to the points shown in Fig. 5. Make sure SI is in the "ofr position and put four "AA" batteries in the holders. Hold the robot in your hand so that the wheels can spin freely* and turn on the power. Both wheels should be turning in the forward direc- tion. If either wheel is turning in the wrong direction youll liave to reverse the leads going to that motor Set RIB and R19 fully clock- wise and set R20 fully coun- terclockwise. With the motors running, bump the left anten- na; LEDl should light and the left wheel should reverse direc- tion for a short period of time {LED2 wiil also light for just a second). Now bump the right antenna; LED2 should light up and the right wheel should change direction. Bump both antennas; LEDl and LED2 should light up and both wheels should change direction. Final assembly Install felt strips on the solder side of the PC board where the battery packs will come in con- tact with it. Lay the battery holders (wMth batteries in- stalled) into chassis with the wires coming out on top near the motors. Set the board onto the standoffs and secure it with one nut on each standoff. Do not overtighten the nuts. Operatiiig tips Find a large area and turn on the robot. The robot works best on a smooth, hard lloor. It does not work well on carpeting, ce- ment, dirt, or asphalt. The back up time delay should alw^a^'s be much shorter than either the left or right time delays- if the left or right delay is really long, the robot will make loops and other strange movements. In small spaces all time delays should be kept short and in larger spaces longer t ime delays work better Make sure that the obstacles the robot encounters are solid all the way down to the floor. When the rubber bands get dirty from prolonged use, they will begin to slip. Replace I he m whenever necessary^ r-e A PC IS THE PERFECT THING to use to accumulate, ma- nipulate, plot, and store the results of an experl- ment. PC-based test equipment has an advan- tage over traditional in- struments: since various instruments share the same PC, the money that would normally be spent duplicating the display, keyboard, etc.. can be saved. That's the idea be- hind tliis series of arti- cles. Well build a number of PC -based test i ns t ru- men ts, including a ca- pacitance meter, a 100- MHz frequency counter, a logic !C tester/identifier and an oscilloscope. We'll start this month with an interface card. The search for the per- fect PC interface begins with the serial port. Un- fortunately, the serial port is loo slow for trans- ferring large quant it les of data needed to control and monitor test equip- ment. Another pos- sibility is the parallel port which can transfer 8 bits in 500 nanoseconds (best case)* Unfortunately the parallel port is not truly bidirectional- A couple of handshake lines can be used as data inputs, but that means converting fast parallel data into slower serial data. Also, several data lines would have to be sacrificed so that they could be used as address lines. Another possible solution would be to connect a circuit directly to the compute r*s ex- pansion bus. That would be very fast and easy to program, but it would require giving up an expansion slot every time you added another device, Whats needed Is a general- purpose, fully bidirectional par- allel port that can select and drive different peripherals all connected to a single generic ribbon cable. That Is all con- tained In the IIOOO Data Inter- face that well build this month. The 1 1 000 can address up to 256 peripheral devices, all con- PC-BASED TEST BENCH In this series of articles we ll be building various PC- controlled test equipment— but first we need a universal interface card. an address DIP switch. As far as software goes, well use BASIC due to it's broad popularity but al- most any other language can be used. Sending a byte Refer to Fig. 1 for the following example. When the BASIC Instruction, ■^OUT 768,85" Is ex- ecuted, the byte *'85'* (0101010!) is sent to ad- I dress '768 ' (where the 1 1000 resides). The PC ex- pansion bus address lines As^A9 are attached to the card-address block, along wit h the ADDRESS ENABLE (AEN) line, which indicates that the addr ess da ta is valid, and the wiute (wi^) line, which indicates that an *'out" was performed. If the AEN and mi lines are low (logic 0) and the ad- dress lines match the DIP switch settings* an 8-bit magnitude comparator In the card-address block changes state fgoes low). That tells the 11000 that the CPU ha s selec ted it. The PC's WHITE pulse, in conjunction with the pulse from the block. STEVE WOLFE nected in parallel, using 25-con- ductor ribbon cable. The 1 1000 is simple to program; an "out" or "write" command sends a byte, and an **in" or "read" com- mand receives a b3rte. IIOOO operation Eacli card in a PC has its own address. That is necessary to ensure that information intend- ed for a certain card is received only by that card, and to ensure that only one card can place data on the bus at a time. Typ- ically, the 11000 is set to address 768 (liex 300}— an address that IBM left available for prototyp- ing. The IIOOO can be re-ad- dressed as needed by changing ENABLE card-address causes the address latch to store the address, and the data latch to store the PC bus data. AL that point, the IIOOO is finished using the expan- sion bus, and it places the data, address, and send pulse on the interface cable that is going to the peripheral. The SENn pulse is sent along as confirmation that the data and address infor- mation is valid. Approximately 750 nanoseconds later, the IIOOO sends a 500-nanosecond peripheral write pulse. By the time the write pulse reaches the peripheral, the data, address, and SEND pulses have linlshed any ringing associated with par- allel interfacing. Additionally each of the signals mentioned are terminated and buffered on the IIOOO and at the peripheral. That defeats any error and noise [reflection, bounce, and RG. I^noco BLOCK DIAGRAM. This intedaee will let your PC communkate with Ihe test equipment weli be working on in future erticles. crosstalk) problems commonly associated with parallel data Iransfen The peripheral re- sponds to the WKiTE pulse by storing the data byte (no-D?) within the location dictated by the address inrormation (ao-a4) that it received. Receiving a byte For the following example, we will execute the line of BASIC: A=iNP(768) : A = IN P(768) : PRINT A. When the address ENABLB (aen) and the PCs read im>) lines are low, the card-ad- dress section once again goes low; and the send and address inrormation is sent to the pe- ripheral. A READ pulse is sen t to the peripheral 500 nanosec- onds la ten which causes the pe- ripheral to send the data back to the 1 1000. The data from the pe- ripheral is stored in the 11000 250 nanoseconds later The sec- ond input statement moves the data from the 1 1000 to the varia- ble (A). Finally, the byte is dis- played on the PCs monitor Control register enable The 1 1000 has the ability to talk to 32 locations within 256 peripheral devices. That tre- mendous flexibility is accom- plished through the use of the control register When the 11000 is set to a base address of 768, it is actually active from 768 to 799, and covers 32 addressable bytes. If we say that the variable "bas" is equal to 768, then one HOOD can cover bas + 0 (7681 to bas + 31 (799K Within the 1 1000, bas + 31 has been de- coded to a single line. In other words, when an "out" is sent to bas + 31, the cren line goes low. When the cren line goes low, any peripheral attached enters a comparator mode. While in that mode, each peripheral compares the information on the data bus with it's own hard- wired identification byte. If they match, that peripheral will at- tach itself to the data bus. In a peripheral where the bytes do not match, that peripheral will ignore or disconnect itself from the data bus. Once a peripheral has been called, it continues to be connected to the data bus until another bas + 31 activates a different peripheral. Suppose peripheral 1 is an A/ D converter with a unit address of 0 and peripheral 2 is a capaci- tance meter with a unit address of 4. An "out bas + 31,0" would select the A/D converter unit. The A/D would not actually do anything other than connect to the bus* After that, outs and ins to addresses between bas + 0 (768) and bas + 30 (798} would cause the A/D peripheral to per- form its Job. An "out bas + 31,4" at this point would remove the A/D converter from the cable and connect the capacitance meter Again, outs and ins in the range bas + 0 to bas + 30 would control the instrument selected. Finally an "out bas + 3L99 ^ would disconnect both of the peripherals from the interface cable. That occurs because there is no device currently con- nected with a hard- wired identi- fication byte of 99, The data bus is eight bits wide, so 256 (2**I different peripherals can be ad- dressed. Leaving bas + 3 1 for ad- dressing different units, 31 a dd r ess es ( 0—3 0 ) re m a i n fo r ac- cessing ICs Within each unit. The total number of locations accessible by one 11000 is 7936 (256x31). Detailed operation Take a look at the timing di- agrams in Figs. 2 and 3 and the schematic in Fig. 4, A 74LS688 8-bit magnitude comparator (ICll compares DIP switch Sis settings to the address present at address lines a5-a9 {PL pins A22-A261, It also checks to see that WR and aen are low. When those conditions are met, ICl pin 19 goes low, telling the 1 1000 that it has been selected by the CPU. Address lines ao-a4 (PI pins A27— A31) are connected to ICIO, a 74LS573 address latch. When pin 19 of ICl goes low. it causes pin 6 of lC2-b (a 74LS86) to go high, latching the address information into ICIO. When PC r ADOflL 1C1 ADDRFSS VALID IC12-4SEHO* WRPtN 121 ADDRESS TO PERfPHERAL M ^ ■ > ■ ■ I nn i<500 nsjf -75011 2000 BS- I ! ! ! I M h M ! 1 M ! IT m- " T^ 500 fls ■{-- ' — " ±i i± FIG. 2—11000 WRITE, or '*out'* 1im^ng sequence. PC ADcm PCRO ICI ADOAESS VALfD IC3^ PIN 6 ICa-4PIH4 ICIS^SEND PWII ICt^bLfU) PIM5_ K^^bRD PIN 12 DATA mm T 1 1 -1 L 1 - r -\ J \- 0 \< 5C 7 I d H - H h F - 20(30 ir r L 1 1 ]a r h -| h n n H r T - 1 ! 1 RG. 3— ilOOO READ, or "fn" timing sequence. the WR and en pulses at the In- puts of IC3~a (a 74LS32) go low, the output of !C3-a does the same. That causes the output of IC2-C to go high and moves [>o^[j7 data from the PC into data latch IC4, Components J C 6 - I C 9 (74HC T22rs) are rising-edge triggered m on os table multi- vibrators (one-shots) triggered by rising pulses. After approxi* mately 500 nanoseconds, the WK and pulses return to their inactive high state and, as a re- sult, the output of lC3'a returns to a high state. The rising edge produced by lC3-a triggers 109- b and IC6-a, The wend pulse, generated by IC9-a. when ANoed with the REND pulse, produces the SEND pulse. The send pulse tells the peripheral that the bus information is valid. The wend and SEND pulses also enable ICIO and 1C4. allowing ao-a4 and D0-D7 onto the peripheral buses* At the same time IC9 b is trig- gered, IC6-a is triggered, pro- ducing a 750-nanosecond delay pulse- As IC6-a times out, it triggers IC6-b. which produces a 500-nanosecond wr pulse that is centered within the 2-(is SEND timing window. The wii and SEND pulses pass through IC13, a 74LS541 line driver/ buffer. The WR pulse is reshaped by R9 and C30 to a waveform more suited to a long cable with inductive reactance. The send pulse Is similarly reshaped by DIP resistor RIO (pins 6 and 11) and 027, During a wr operation, the data lines do-d7 are conditioned by Rll, R16, and C31-C38 on the way to the peripheral device. The address lines at the output of ICIO (ao-a4) are conditioned by RIO and 022-02 6, Th ose address lines and the wend pulse are applied to 101 1, a7 4L5138 demultiplex- er If WKNU is low and the ad- dress is equal to the base address (768) plus thirty one (as discussed earlier), pin 7 of 10 11 goes low producing the cren pulse. 11000 PARTS UST All Sisters are yj-watt, untess otherwise noted. R1, R3, R5— 1000 ohms, 5% R2. R6— 4320 ohms R4— 9090 ohms R7. R&— 20.000 ohms R9— 33 ohms RIO, Rn— 33 ohms, \B*^n DIP resistor R12-R14 — 10,000 ohms, multitum po- tentiometer R15^700 ohms, 10-pin SIP restslor R16— 22tX3 ohms» 10-pin SIP resistor Capacitors C1-C13— 0.15 \lP, 50 volts, monolythic Of polystyrene C14-C21— 105 pF, too volts, dipped mica 022^29—1500 pF. 63 volts, poly- styrene C30— 0.001 jiF, 100 volts, ceramic disc C31-C38— 220 pF 100 votls, ceramic disc C39— 100 |iF 25 volts, efeclroSylic C40-C45— 10 ^lF 35 volts, electrolytic Sein I conductors ICl— 74LS688D B-bit magnitude com- parator IC2— 741S86D quad 2-rnput X OR gat© IC3— 74LS32D quad 2-input OR gate IC4. IC5, IC10-74LS573O octat latch IC6-IC9— 74HCT22ID dual om shot IC11— 74LS13BO demultiplejter IC12— 74LS08D quad 2 input AND gale IC13— 74IS5410 octal buffer Other components ji— Right-angle PC-mount female DB25 connector 81 — 8- position DIP switch Miscettaneous: 11000 PC tK)ard. PC mounting bracket and hardware with DB25 cutout, solder, etc. i CD 9- 9 m S 3 41 * + !_C41 t 5Jr Receiving a byte When receiving a byte. ICl op- erates the same as when it is sending except that the rd line goes low. The address data (ao^a4) is again stored in ICIO, The RD and en pulses go lovv; and as a result lC3-b transit ions low. The PC then reads back the contents of IC5. (The informa- tion read bacic at this point is irrelevant, since information from the peripheral unit has not reached the 1 1000 yet,) As the UD and en pulses end, a ris- ing pulse edge occurs at IC3, That activates lC7-a. IC8-a, and IC9-a. The REND pulse is produced by IC9*a, which, when it passes through IC12-d, becomes send, A 500-nanosecond delay pulse Is produced by IC7-a; as IC7-a times out, it triggers IC7-b, which produces a 1000-nanose- cond rD pulse which is sent to the peripheral unit. (The send pulse and address Information arrived at the peripheral 500 nanoseconds earlier) Upon re- ceiving the RD pulse, the pe- ripheral sends the do-d? data to the 11000 (IC8-a went active at the same time as IC7-a, and pro- duced a delay pulse of 750 nano- seconds). As IC8-a times out. it triggers IC8-b to produce a 500- nanosecond latching pulse. The pulse controls the ijvtlh line of IC5 and stores the information sent by the peripheral during the (still active) 1000-nanose- cond RD pulse, A second identi- cal input statement will now cause lC3-b to go low. That again activates ICS and returns valid data to the PC. 11000 construction To buiid the 11 000 interface, you can either buy a PC board from the source mentioned in the Parts List or make one from the foil patterns weVe provided. Install parts on the board as shown in Fig. 5. You will notice that for many of the capacitors, there are three holes on the board, with two of them elec- trically the same. Those two holes are for mounting capaci- tors of different slices. Use the pair of holes that best fit the ca- pacitors you use. Figure 6 shows a completed card. ft: f 3m3 »7 » i IG7 m X CIS + * ^ 1C8 4 * * « » 1 ) ■■ IC3 * «— R5— • •! ^ . n ::z^:zr*j.,fe 3 ' IC11 SI 1 t i f X R15 )■ 1C ■1 P— m : / ' I C fllUIIMUIIIMtiilll .C44 RG- 5— INSTALL PARTS AS SHOWN HERE. For many of the capacitors mere are tiirei mounting holes to accommodate diffetent-slzed capacttors. UJ EE 44 FIG, e^OMPLETED INTERFACE CARD. This is installed in one of your PCs expan- sion slots. The front end Any IlOOO'Compatible pe- ripheral must contain an inter- face sectfon to control the flow of data and clean up any noisy pulses. We'll call this interlace section the "front end." The front end will be nearly identical for each 1 1000- compatible pe- ripheral showcased in this se- ries of articles. Each peripheral will contain its own front end. which will be included on the main PC board. Although we will not be discussing any of the PC peripherals this month, lets go over the operation of the front end now. As shown in Fig. 7, each front end contains a data termina- tion block and an address and handshake termination block* Tlicse sections are activated by inserting push-on jumpers. If the jumpers are removed, the termination section mil be elec- trically inert. The IIOOO is capa- ble of addressing up to 256 [2**) TO mU FROM, THE n 000 DATA TEHMrNAIIOrj SEHD. CREK ADDRESS AMD | HANDSHAKE TERMirJATlOM \ ADDRESS LINES r PEflPHERAL K . ADDRESS - I COMPARATOR 1- DATA WR+CREN ADDRESS AND HANDSHAKE BUFFER mi flmiRECTIOfJAL OAIA REGISTER [DATA WR, RD. SEND ADDRESS LINES fA0-A4) TO REMAJKDER OFPERlPHEaAL RG. 7— ANY 11000-COMPAT18LE PERIPHERAL mysl contain an interface section to control the flow of data and clean up any noisy pulses. Ttiis front end wili be nearly Identical for all of Ihe periptierals. COMPONENT SIDE of the ItOOO interface board. peripherals. The DB-25 con- nectors on the rear of each pe- ripheral are simply connected in parallel with one another Itr- mination of tlie data bus must occur at the most distant point on the bus and only at that point. If more than one pe- ripheral were terminated at the same place, the termination im- pedance and its location would be altered, thus distorting the performance of the front ends. After passing the active or in- active termination section, the data bus is attached to the Pe- ripheral Address Comparator (PAC) and the Bidirectional Data Register (BDR), The PAC is responsible for activating a pe- ripheral called by chen as pre- viously described. Each pe- ripherals PAC section contains its own unique address. If, dur- ing an active cren pulse, the data on the bus matches the PAC address* the PAC section produces a low boakd bnaule handshake (bfcn). That signal and its complement (ben) con- nect the remainder of the pe- ripheral to the data bus and handshake lines (ro, wk, etc). The BDR is now capable of passing data to, and receiving data from, the main peripheral circuitry. The BDR is controlled by iu>, SEND, and bkn. Those lines tell the BDR the direction of data movement as well as the timing of that movement. After passing the active or inactive termination section, the ad- dress and handshake signals enter the address and hand- shake buffer The signals are rounded by the termination sec- lions to minimize crosstalk and other noise associated with fast rise and fall times. The address J3 9- 9' m S 3 45 _eij C13i 220pF 15 009909 6 6 6 6 i OS Iff m 4 DO J_I1L e 02 o 6 ? 9 CI !4 .11 7D 7ilS4«f m BO A7 A1 m AG 66 H2 BS A3 B3 A4 n B4 P(nPK£RAL (SEE CHAim 12 4>ia la +12 4>12 20 QNO/KEV 21 nm BMP CHEN C9 4 SEND +5V I c2o-m O AOtBE SS cow IGUFUTIOJI ncioi K3 5 ^ ii *5V AOOR ^5V 4 noo4 -12V RG. 8— FRONT-END SCHEMATIC. Each front end con lams a da la termination block 4^ and an address and handshake termination b^ock that use push*on jumpers. SOLDER SIDE of the IIDOO interlace board. and handshake buffer restores the original fast rise and fall times of the signais. Sending a byte When describing software -re- lated functions, well again use BASIC due its wide popularity and well assume the following initial conditions: • The base address of the 1 1000 Is 768 (hex 300), • The front end of the pe- ripheral has not been selected. • The address of the peripheral is 4, Refer to the front-end sche- matic in Fig, 8 and the following source code: 10 BAS = 76S 20 OUT BAS + 3L4 30 OUTBAS-H2J70 Line 10 in that example as- signs the address ' 768" to the variable "has." Line 20 causes the si:nd and cren pulses at IC6 pins 8 and 9 to go low (refer to the timing diagrams in Figs. 2 and 3). If the shorting blocks have been installed at header J2, then the rd. wh, address, SEND, and cRKN lines are all ter- minated. Line driver 1C6 re- stores the original wave shape of any signals fed to it . The sknd and CREN pulses exit ICS at pins 12 and IL [f the shorting blocks have been installed at Jl, then the data lines do-d7 are termi- nated. Either way the data is fed to the input of latch ICl; IC3 is inactive at this time. At a time 750 nanoseconds later, the wr pulse enters iC5-a where it is reshaped. It is combined with the cleansed cren pulse by 1C4- d to produce the wn cren pulse. The WR CREN pulse latches the data (a binarj^ 4) into ICl. The FRONT-END PARTS LIST ' Resistors R1— 33 ohms, t6-pin DIP resistor R2— 2200 ohms, 10-pin SIP msislor R3— lOOO ohms, lO^pin SIP resistor Capacitors C1-C7--0.15 |tR 50 volts, monolythic or poiystyrene G8^1. C20-C28— 1500 pR 63 volts, polystyrene I C1 2-01 &— 220 pF, 100 volts, ceramic disc Semiconductors ICl— 74LS573D octal latch . \C2—7AlSmBD 8-bil magnilude com- parator IC3— 74LS245D octal transceiver (C4— 74LS02D quad 2'inpiJt NOR gate IG5, IC6— octal buffer IC7— 74LS08D quad 2-input AND gate Ottier components Ji— 16-pin male header J2— 18-pin mate header J3^Right -angle PC-mount mate DB25 connector Miscetlaneous: 17 shorting blocks (for J1 and J2), solder, etc. Note; The following Items are avail- able from T5W Electronics Corp*^ 275& N, University Drive, Suite 16Bp Sunrise, FL 33322 (305) 748-3387: * 11000 kit^65.00 * HOOD PC board only— S35.00 * 11000* assembled and tested — S77.00 m 6-foot interface cable {DB-IS-B}— SI 2.95 Add S3.00 S&H for each order. Send check or money order only. binary 4 appears at the output of !C1 and, subsequently, at the input of IC2, an 8-blt magnL- lude comparator The magni- tude comparator (IC2) com- pares the byte fed into it from ICl with its hardwired address (see the IC2 address-configura- tion chart contained in Fig, 8), If the two bytes match, pin 19 of IC2 goes low (benI, bEn is then combined with send by fC4-b to produce the output enable control line signal toll used by !C3, which transfers all the data to and from the peripheral. When Wn is high. IC3 fs Inac- tive, The DEN line (ben*s compli- ment) is produced at IC4-C and enables or disables the chip-se- lect section in the peripheral cir- cuitry The HEN and ben lines are the primary lines that determine whether a peripheral on the bus is active or dormant. The direc- tion pin on IC3 (niu) is con- trolled by the rd pulse. The ^ pulse is high during a WTite op- 1 ^-^^''W**'- %mmmm O I Your Ticket To Over 28,000 technicians heve gained odmii- Tance wo r Ed Wide as certified professionals. Let your ticket start opaning daors for you. ISCET offers Jouraevman oertjficatior^ if* ConsufTver Electronics, Industrial, Medical, Communications, Radar, Computt^r and Video. For more irt format ion, contact the International Society of Certified Electro^ nic* Techmcians, 2708 West Berry Street. Fort Worth, TX 76109; (317) 92V9101. Name _ Add rets ^ City State .2ip. I _S€nd material abotJi ISCET and becommg certified. Send one "Stuiiv Guide for The Efi* Associate Level CET Test Y closed is $10 (inc. postage). Over 750,000 readers of earlier odttians of The Forrest Mims Engineer's Notebook iigretf— nobody knows practiced IC applicatLons like Forres! Mims! This no%vly- n^visc!j)ly voltages, and signal wavefonns— so you can qiitckly duplicateeacti circuit. There^s also pracUciil in- formal ion on construction meth- ods, troubleshooting, and inter- (acl ng d i ff ercnl \C fam iUes, 1 f you work with ICs you gotta gel this , book! Only 51 if. 95 df bookstores orelecSmntc pan^i dmhts!. Or onhr d/rwct from lii^^hTifxt! Add S3 shipping {S4 \p (^Jiimh. Sa t}ismviit;rv}, Ol ptmiKo add solaic (ax- HighText eration, allowing data to flow f rom the 1 1000 side of IC3 to the peripheral side of ICS, Line 20 in the software exam- ple activates the peripheral by causing BEN to transition low. Line 30 in the software example will not affect ICl or IC2. As ex- plained earlien only an "out" to bas + 31 wiU actirate cren. Line 30 will cause the following se- quence of events: seivd will go low The data (a decimal 170 in this case) will pass through IC3 to the peripheral circuitry. Ad- dress inrormation (a decimal 2 in this case) will pass through ICS to the peripheral circuitry. At a time 750 nanoseconds later, a 500-nanosccond wh pulse will pass through ICS to the peripheral clrcultiry. The ad- dress is decoded by the chip-se- lect circuit in the peripheral and the wr pulse is then routed to the addressed IC. Any "out** to an address between bas + 0 and bas + 30 will initiate the process commanded by line 30* Tbrmiiiation The termination sections are composed of JL C12-C19, R2, J2, C20-C28. and R3. Those sections provide a termination Impedance to ground as well as an R-C time constant. The ter- mination impedance reduces the reflected signal caused by the inductive and resistive properties of Ihe sLx-foot cable. The R-C time constant slows down the rise and fall times of the signal in the cable, thus re- ducing crosstalk. As stated ear- lier, The original transition times are subsequently re- stored. Receiving a byte As we describe how the front end end receives a byte from the 11000 Interface, lets assume the following initial conditions: • The base address of the 11000 Is 768 (hex 300). • The front end of the pe- ripheral has been activated at an earlier time. Next refer to the following source code: 40 A=INP(BASh-3) 50 A=INP(BAS^31 60 PRINT A Lines 10-30 are assumed to have been executed pre\'iously. Therefore, our theoretical pe- ripheral has already been se- lected (activated)- Line 40 pro- duces a read ftinction as described earlien The send pulse goes low. The address lines (AO-A4) function as they did during the wTiie function. At a time 500 nanoseconds la ten a l-\is rd pulse is received by the front end. It is reshaped by IC5-C and lC5-d. The rd pulse passes through lC7-d to IC3 pin L The peripheral side of 1C3 be- comes an octal input while the 1 1000 side of 1C3 becomes an octal output. The RD pulse arrives at the read chip-select section of the peripheral circuitry. The j^d pulse* In conjunction with the address lines, cause the target IC to place its byte onto the bus. The transmitted byte passes through IC3 to the IIOOO where it is latched. A data bus direc* tional delay (DBDD) is provided by IC5-e-IC5-h in combination with lC7-a-lC7-d. The DBDD provides a delay after the read cycle has finished before returning 1C3 to its nor- mal "output" configuration. That prevents IC3*s peripheral side from going into its low- im- pedance state before the !C that was just read is able to de-actl- vate. Line 50 causes the byte latched in the 11000 to be sent to the PC where it is stored under the variable "A." Line 60 prints the value contained In variable "A" on the screen. As mentioned before, theres no separate front end PC board; each peripheral contains its own front end. Next month youll see the front-end parts In- stalled on the first peripheral board we'll work on : the TIOOl. That peripheral contains a 100- MHz frequency counter for dig* ital signals, a period event meter, and a capacitance meter covering 1 picofarad to 10.000 microfarads. Other PC -based test instruments that we will build in future articles, include a logic-lC tester/identifier. and an A/D-D/A peripheral that can also be used as a low-frequency 8-channel digital storage os- cilloscope, R-E eleclronic This solid-state thermostat can replace those old mechanical units — at a cost of less than twenty dollars! RODNEY A, KREUTER THE MEASUREMENT AND CONTROL of temperature is one area in which electronics has had a great impact. From "set back" home thermostats to laboratory controllers with ±0.001-degree accuracy and digital fever ther- mometers, the use of elec- tronics has all but eliminated mechanical systems. Many methods are used for measuring and controlling tem- perature. Including the expan- sion of mercurj' or alcohoK bi- metallic strips, thermistors, silicon sensors, and thermo- couples. Each has its advan- tages and disadvantages. The author was recently asked to design an inexpensive thermostat to replace some old bi-metalllc-type thermostats. The new thermostat had to meet the ± S'^C accuracy of the bi-metalllc strips, have a - 50 to -i-150''C range, and cost less than twenty dollars. A simple solid-state thermostat was the only solution. Whether you're trying to keep a fish-tank temperature to with- in rc, maintain working tem- perature for PC -board etchant. shutdown an overheated ampli- fier, or turn on cooling fans, youll find that this simple solid- state thermostat will do the job. Note that this project is oniy a controller, so you must supply the heater (or cooler), a suitable relay and a temperature-mea- suring device for calibration. Looking around Before anyone decides to de- sign and build something. It pays to have a look around to see whats available on the mar- ket. First there's the Radio- Shack Thermometer/Controller. Tbtal cost (with switches, etc.) is about twenty eight dollars. The temperature range is -40 to + 50°C ( -40 to + 122T), and it has a digital readout and tem- perature memory So far so good — if the lemperature range suits your needs. Maximum measurement speed is once per second. However the real draw- back Is that if the temperature limit is exceeded, the output goes high for one minute; dur- ing that time period the temper- ature is not measured! National Semiconductor has been making a number of temp- erature sensor/controllers for at least 15 years. The LM3911 (-25 to -H85"C) and the LM35 ( - 55 to -f- 150°C) are two exam- ples. They are easy to work with, but they are more difficult to find and ones with a large tem- perature range aren't exactly cheap. Sensors are also made by Lin- ear Technology {the LM134 with a -55 to +125''C range) and Analog Devices (the AD590 wl th a - 55 to 150°C range) as well as dozens of others. The only catch, besides availability is that they are precision sensors meant to measure as well as control temperature. They are also quite expensive. Complete controllers are also made by other companies such as Omega, but the cost Is about the same as a cheap personal computer That is due partly to super accuracy and digital tem- perature readout. J] to O m a 53 Rollin' yotir own When so many people are making temperature sensor/ conlroliers, why build one from scratch? There are two basic reasons: • Commonly available parts can be used. • You can control such param- eters as accuracy and tempera- ture measurement bandwidth. Theory of operation If a constant current is passed through an ordinary sil- icon diode, the voltage across the diode will be a function of temperature. There are more accurate w^ys to measure and control temperature, but at twenty for a dollar you can't beat the price, and control accuracy of ±0,5°C is typical- The actual voltage across the diode with 1 millianip of current passing through it is about 0.75 volt at -50''C and 0.35 volt at ISO^C. That works out to about 2 millivolts per ^C. Although a controller could be made to work at that level, a little ampli- fication makes things much simpler The schematic of the control- ler is shown in Fig. L Trau- slstors Ql and Q2 make up the l-miUiamp constant -current source for the temperature- sensing diode, DL The base- emitter junction of Ql is used to temperature-compcnsate the base-emitter drop of 92, The l.25-volt reference of the LM317 regulator appears across re- sistor R4, keeping the emitter current (and therefore the col- lector current) of 92 constant at about 1 milHamp. The actual amount of current isn't nearly as critical as the fact that the current remains constant. Differential amplifier ICl-a sen'es two purposes. The first is to subtract a DC voltage from the temperature-sensing diode DL Thats necessary so that a DC amplifier can be used to am- plify the signal from Dl without saiuratingi The signal is also in- verted by ICl-a so that an in- crease in temperature produces an increase in voUage, Op-amp ICl-b is configured with a gain of 11 (l+Rll/RlO), That makes the Job of com- parator ICl-d easier. The temperature set point is controlled by resistor R15 and bufTered by ICl-c. Note that by changing the values of R14 and R16 you can restrict the control range, making it easy to vary the set point in very fine steps. Using the values shouTi, control is adjustable from about - 50 to RG. 1 — CQ^^110LLER SCHEMATIC. If a constant-current is applied to a diode (01 in this case), the voltage across the diode witl be a function of temperature. FIG. 2— PARTS-PLACEMENT DIAGRAM. Any methad of construction can be used* but it s best to use a PC board. You can make one from the foil pattern we've pro- vided or buy one from the source men- tioned m the Parts List* FIG. 3— THE TEMPERATURE-SENSING diode can be seaied in a fength of gfass tubing and sealed with RTV siticone. You must use a shielded cabie between the probe and the measuring circuit. + Wilh thai much range, a small nio\'ement of a single- lurn polcnliomctcr will produce a large change in the set point. A ten-turn potentiometer would be a better choice for a large- range thermostat. Table 1 shows recommended values for R14, R15, and R16 for smaller temperature ranges. Comparator ICl-d compares the set-point voltage with the output voltage of tCl-c. If the voUage al TP3 is greater than TP4. the output of the com- parator will be low, thus shut- ting off transistor QS. If more heat is needed, the voltage at TP^ will be less tlian TP4 and the comparator output will go high, turning on 93. Resistors R18 and R19 pro- vide some hysteresis. Providing a small amount of hysteresis in a comparator ensures a smooth transition from one state to the othen Although it limits the ac- curacy somewhat* the benefits far outw^eigh the disadvan- tages. Without hysteresis, the output of the comparator would dither, or oscillate from one state to the other when the in* puts are about equal. Imagine ordering an oil-buining furnace to turn on and off a thousand times a second! The amount of hysteresis can be controlled by resistors R18 and R19, Decreasing Rl 8 will in- crease the hysteresis and cause a greater temperature variation in the controller. For example, using the highest resistance, the temperature window tnight be 0,5^C. At the lowest it tnight be 3'C. The output of Ihe controller can control a conventional or solid-state relay, A solid-state re- lay is preferable since its re- liability is much greater than that of a conventional relay (If you'd like to build your own sol- id-state relay. see Radio-Elcc- trooics. May 1992 J Any relay rated from five to twelve volts will work if you connect it to the positive side of Cl through the appropriate resistor. That re- sistor value can be obtained by dividing the voltage drop re- quired by the current con- sumed by the relay. If a conventional relay is used, a snubbing diode such as a 1N4002 should be used to pro- tect Q3 when the relay turns off. Construction Any method of construction can be used since there is nothing critical about the cir- cuit layout, but it will be easier using a PC board made from the foil pattern we ve provided or one purchased from the source mentioned in the Parts List, Do not substitute another reg- ulator for the LM317. In addi- tion to providing a regulated voltage, the LM317's L25-volt reference is used to operate the constant-current source for di- ode DL Figure 2 shows the parts-placement diagram. TWelve-volts AC can be sup- plied from just about any trans- former since only a fe\v milli- amps are required— not count- ing the relay current. Relay current of up to 100 milliamps can be handled by Q3, The temperature probe can be made of metal or glass. The di- ode is so small that it can be pul into standard glass tubing and sealed with RTV (room- temper- ature vulcanizing) silicone. Coating the diode with RTV sil- 55 TABLE 1— RESISTOR VALUES Temperature Range (Degrees C) R14 R15 R16 -50 to -30 lOK 1K 33011 -30 to -10 9.1 K 1K 1.2K -10 to 15 8.2K IK 2.2K 15 to 35 7.5K IK 3.3K 35 to 55 6,2K IK 4,3K 55 10 75 5.1K IK 5,1 K 75 to 95 4.3K IK 6.2K 95 to 115 3.3K IK 6.6K 115 to 135 2.2K 1K 8.2K 135 to 155 1.2K 1K 9JK Icone might also work although the thermal lime conslanl would probably increase using that method. Yoti must use a shielded cable between the probe and the measuring cir- cuit. Figure 3 is a close-up view of the probe assembly with tlic diode installed in a length of glass- tubing. The printed circuit board Is designed to accept two different trim potent iometcrs, hence the four holes instead of three. If you must adjust the tempera- ture often, you might opt to run wires from the PCB to standard- type potentiometers. Figure 4 shows the author's completed prototype. Itesting You should first test the I- milliamp current source, if the voltage across R4 measures about L2, you^re in business* Placing a milllammeter in series with Dl can confirm that. For the purposes of testing. It's handy to replace Dl v%4ih a IK potentiometer. Since a con- stant current of 1 miUiamp is flowing through the resistor a voltage from 6 to 1 volt can be obtained depending on its set- ting. Of course that range is too much since the diode voltage varies only from about 0.8 vol I at -50°C to about 0,3 volt at -h 150"C, First measure the voltage from pin 3 of ICl to ground. It should be about 0.55 volt. Using the IK potentiometer ad- just TPl for the voltages shown In Table 2. and make sure the TP2 and TP3 voltages agree with Table 2 for each voltage at TPL Next check the temperature set- point range. Measure the volt' age from TP4 to ground; with the potentiometer set at the ex- PARTS LIST All resistors are Vi-watt, 5%, un- less otherwise noted. Rt— 100 ohms R2— 750 ohms R3. Ria R12. R1 7— 10.000 ohms R4— 1200 ohms R5 — 1000 ohms R6, R7, Rl 1—100.000 ohms R&— 1 megohm R9— 56,000 ohms R13— 2200 ohms R14 — 1600 ohms (see text) R15 — 10.000-ohm potentiometer (see text) R16— 330 ohms (see text) R18 — 1-megohm potentiometer Rl 9— 470.000 ohms Capacitors Cl— 470 fiR 25 volts, electrolytic C2, OS— 10 ^lR 16 volts, electrolytic C3— 0.1 Myfar Semiconductors ICl— LM324 quad op-amp IC2— UVi317L voltage regulator Dl. D2— 1N4t48 diode LED1 — light-emitting diode, any color Q1. Q2— 2N3906 PHP transistor Q3— 3N3904 NPN transistor BR1— 50-volt bridge rectifier Miscellaneous: 12- volt AC power supply. PC boardn glass or other similar tube tor temperature probe, RTV cement, wire, solder, etc. Note: The following items are available from Q-Sat, PO Box 110, Boalsburg, PA ie827: • PC board (Temp-PCB)— $7,00 postpaid • All parts (including PC board) except 12-volt trans- former (Temp- KIT)— Si 8.00 postpaid Pennsylvania residents please add 6% sales tax. ireme counterclockwise posi- tion, TP4 should be about 0.31 volt. Clockwise, it should be about 8.88 volts. If the testing works out, you're ready for the real test. With R15 set counterclockwise and the temperature-sensing diode at room temperature, LEDl (and Q3) should be off, llirn R15 slowly clockwise until the LED comes on. Now heat the diode with a soldering iron or match; the LED should go off. If everything is altright» the final step is to calibrate the controller with an accurate temperature- measuring device. n-E RG. 4— THE AUTHOR'S PROTOTVPE. If you wHI need to adjust the temperature often, run wtfes from the PCB to standard-type potentiometers. TABLE 2— TEST-POINT VOLTAGES Approximate Temperature TPl TP2 TP3 CC) 0.300 0.766 8.38 150 0.350 0.717 7,84 0.400 0.665 7.28 0,450 0.616 6.74 0.500 0.566 6.81 50 0.550 0.515 5.63 0.600 0.465 5,08 0,650 0.415 4.54 0.700 0.364 3.97 0.750 0.315 3.43 -50 0.800 0,263 2.87 0.850 0.212 2.31 EDGARDO PEREZ Learn to put mature high performance video amplifiers to work in your latest video and RF circuits. BANDWIDTHS OFTIIE LJ^TEST MONO- lit hie video amp! t Piers have now reached 600 megahertz. That performance has been achieved in differential two-stage video amplifier ICs because of re- cently introduced vertically in- tegrated PNP structures. These new products have pre-empted earlier more mature video amp- lifiers. Including the 592 and 733, from many new designs. Nevertheless, the 592 and 733, introduced in the early 1970s for such applications as tape- or disk-memory read am- plifiers remain versatile devices. Leading-edge video amps in their day they offered typical differential voltage gains of 400 and adjustable pass bands. Moreover neither required fre- quency compensation. The typ- ical bandwidth of the 592 is 90 megahertz while that of the 733 is 120 megahertz. Rise time on the 733 is 2.5 nanoseconds, and tj-pical propagation delay time is 3.6 nanoseconds. Originally developed by Fair- child as the (xA592 and ^^733, the parts were second sourced by IC suppliers including Motorola, National Semicon- ductor, Slgnetics, Tfexas Instru* ments. and VTC Inc. They were redesignated by those manufac- turers with their prefixes such as MC1733. LM592, SE592, TL592, and VA592. After making them for many years Motorola and National Semiconductor recently bowed out. but Signetics, TL and VTC have confirmed that they are still producing one or both of those video amps. Both devices are available in a varietj^ of pack- ages including plastic and ce- ramic DlPs, and metal cans. Although their performance has been superseded by newer video amps, the characteristics of the 592 and 733 remain at- tractive. They might no longer be at the forefront of video am- plificr IC technology but they arc definitely not obsolete! What's more» maturity has brought about a steady decline in pricing. Bargain prices as low as 25 cents apiece have been reported, but you can expect to pay lYom 70 to 90 cents for a plastic-DIP version from your distributor There are slight differences in performance between the 592 which was introduced in about 1974, and the 733 which was introduced a few years lalcn For most of the circuits In this arti- cle the 592 and 733 are pin-for- pin interchangeable. Figure 1 is the schematic of the 592. with an inset showing the circuit dlf* ferences in the 733, (The 592 has two transistors in its first- stage differential amplifier (Ql 1 and Q12) while the 733 hasonlv one (Qll). Designers use both of these video amps in the differential output mode for DC applica- tions, or with AC coupling for single-ended output. In place of external feedback to control gain, the video amps have built- in internal local feedback for op- eration in the open-loop mode only. Because they include only NPN transistors (as shown in Fig. 1), the outputs are always 2.4 to 3.4 volts above ground when both inputs are grounded. I Construction guidelines i You can take advantage of the g low prices for these devices in N your next RF- or video-circuit J design ifyou are willing to follow some basic rules for designing m and building radio- frequency S circuits. So before you start to | build anything, let's take time to g review those guidelines. • Use only passive components that are stable at radio frequen- cies. For example, use only car- 57 INPUT 2 INPUT 1 .4K 2.4K 01 02 son 10K 1.1K 5 03 500 04 7K 7K 09 Q10 OUTPUT 1 "1 OUTPUT 2 300n mn FIG. 1— SCHEMATTC FOR THE S92 with an inset showing the drHerences in the 733. Transfstor Q11 and three related resistors replace transistors Qtt and 012 and two emitter resistors. bon-composKion or non-induc- Lfve metal-nim resistors. For small capacitance values, use only silvered-mica (rather than foil and mica)* ceramic, and my- lar-lilm capacitors. For large ca- pacitance values, use solid or foil tantalum capacitors in place of aluminum electrolytlcs. • Keep ail traces on your PC boards short and wide to mini- mize both stray inductance and stray signal coupling from the input to the output. That pre- caution preserves the system bandwidth and eliminates pos- sible circuit oscillation. • Keep capacitance and re- sistor values as small as possi- ble to minimize all unwanted time constants. High capaci- tance and resistance values could also cause oscillation or reduce bandwidth. This is es- pecially true for feedback re- sistors. The use of resistors with values of less than 2 K is a good point of departure in re- sistor selection. • Use a ground plane to keep return resistances as low as possible. Avoid point-to-point wiring but if you must use that construction technique, be sure to return all ground leads to one and only one point to re- duce the possibility of ground loops. In circuits where large stray noise signals could show up. suitable input shielding is required. • Each power supply lead of the video amplifier should be prop- erly bypassed to ground with a capacitor located as close to the video-amp as possible, A 10- ohm resistor ahead of the ca- pacitor will also help to decoup- le the power supply from the amplifier In addition, if you have a problem decoupling the power supply from the video amp« try a radio-frequency choke (RIfC) in place of the re- sistor, or slide a few ferrite beads on the resistors leads. • Keep the input resistance as low as possible to reduce the effects of input noise currents. Commimications applications Both monolithic video amps will give you access to the emit- ters of their tirst differential am- plifier stages (as shown in Fig, 1) via gain-select pins Gj^^. G^^^. Gj^. and G^iy By placing a vari- able potentiometer betu^een the G and G^ pins (pins 4 and 1 1 on the DIP), you can adjust dif- ferential voltage gain over a range of 250 to 600. With the addition of frequen- cy-dependent components, these IC's can function as v^deo- band active tilters or RF ampli- fiers* Figure 3 illustrates live possible filter configurations. The components are placed across the G^^ and Gu^ pins (4 and 11 on the DIP) for the out- OAIM S£L£CT GAJN^LKJT OtJTPini OUTPUT 2 GAiN SELECT INPUT 2 GAlHSaiCT- GAIN SELECT NC OUTPUT 2 14 iNFtiri NC GAIN SELECT mti SELECT NC OUTPlfT 1 riG. 2— TOP VIEWS OF 592 and 733 packages I {s) metal can and (b) ceramic and plastic DIR o IDt— o ^ XTAL 1^ J L 1 t 1 /J r 1 o- 3211 1 1 41 1 c o — )| 0 1 1 1 ! 1 11 o — — nnnyr^ RG, 3— ACTIVE FILTER using the 733 and 592: (a) crystal {p) notch, (c) band- pass, (d) high-pass and, (e) low-pass. J2 _ BNC FIG, 4^A 4.5nHHi AMPLIFIER based on the 592 video amp. OUTPUT 1 RG, S^A GENERAL PURPOSE PREAMPUFIER based on eittier the 592 or 733 video amps. J— i -5V FIG^ 6— FREQUENCY COUNTER based on either the 592 or 733 video amps. pui responses. ^ 9 of ^92 converts the In Fig, 4, the addition of a 4,5- circuit into an audio intermedi- MHz ceramic filter between pins ate-frequency amplifier that is sultabie for use with TV signals. Many variations are possible. You could also place passive fil- ters on the input, output, and gain-control pins for even better signal rejection and separation. The 592. like the 733. per- mits you to control gain with an external impedance value. How- ever the 733s differential volt- age gain (A^^ti) can be as low as 8 wllh all gain- select pins open, an option not available on the 592. Thus, in a filter applica- tion, the unwanted signal will have a theoretical voltage gain of 20 dB minimum, making the 592 unsuitable for that applica- tion. Howeven the video amps can usually be interchanged with minimal or no modifica* tions to your basic design. Instrumentation applicaticins Because these amplifiers are wide-band devices, they are suitable for use as preamplifiers In meter and oscilloscope cir- cuits. Figure 5 shows a basic general-purpose instrumenta- tion preamplifier that will oper- ate at frequencies down to DC. The preamplifier in Fig, 5 will work with either the 592 or 733, You can set resistor R3 {R,j^t) to meet your requirements up to a maximum of a few hundred ohms. This design Is limited^ howeven by its Inherent low in- put impedance and high output impedance. Figure 6 shows an improve- ment on the circuit in Fig. 5 making it suitable as a pre- amplifier for a frequency coun- ter preamplifier An FET buffer Ql has been placed on the input of the 592 or 733, and the input impedance has been increased to 1 Megohm wllh Rl . Input pro- tection is provided by forward- biased diodes Dl to D4 which prevent input signals from over- driv^ing the amplifier. Diodes D3 and D4 also keep the video- amp's outputs from saturating with increased switching fre- X Z- D5 1N4160 1MEG -ri2pF R2V ion' R22 10U ft20 J2 Hour our -SVTD-7V Fia 8— SECrrON of PREAMPLIRER circuit of Rg. 7 showing additional oulput compensation. *+5VT0 + 7V 1MPUT -6VT0-7V RG. 9— GENERAL PURPOSE OUTPUT ampHfier based on either the 592 or 733 video amps. quency. The FET bufrer has a bandwidth of 100 MHz so it will not restrict the bandwidth of the video amp. For interfacing the pre- amplifier to TTL devices such as those found in a TTL frequency counter the circuit in Fig. G aiso has an oulput buffer and TTL translator made up of Q4, Q5, and a 7414 inverter. Those will operate to 45 MHz witli the gain of the 592 or 733 set to 10. (The gain pins of the 733 are left open.) To obtain measurable gain from the 592, an emitier resistor of the proper value must be placed across the gain- select inputs Gj,^ and (pins 4 and 11 of the DlPl Alter- natively, a IK potentiometer can be adjusted for the desired gain. If you want to design your own oscilloscope, modify the circuit in Fig, 6 to those shown in Figs, 7 or 8, Both are os- cilloscope preamplifier circuits that will operate at frequencies up to 10 MHz. In those pre- amplifiers more elaborate input circuits and gain- switching ar- rangements can produce the standard 1-2-5 calibrated os- cilloscope steps with a range from 10 millivolts per division to 5 volts per division. Figure 7 shows a method for coupling I he preamplifier to an oscilloscopes vertical deflection amplifier for DC measurement without concern for the DC off- set which occurs at the outputs. In that wav; the equal offset at both outputs of the video amp are nulled by the common-mode rejection ratio (CMRR) inherent in the vertical-deflection dif- ferential amplifier. Capacitors C3 to C5 are input- compensa- tion capacitors that can be ad- justed with a square-wave input after the preamplifier has been completed and tested. TVimmer capacitors C14 through C16 compensate a ten-power magni- fication probe so that it will re- spond the same way to all input attenuators. The circuit in Fig. 8 shows a modification of Fig. 7. It permits the video amp to be used in a single-output mode by eliminat- ing the DC offset. A voltage- shifter arrangement around 94 performs that function. With the related components shown, the output of Q4s collector is zero volts. To maintain the bandwidth of the video amp, a bulfer configuration made up of Q5 and Q6 isolates the load from the high impedance of Q4*s collector. The buffer will drive a 50-ohm load to 20 MHz at about 3 volts peak-io-peak* This characteristic makes it possible to couple the pre- amplifier to the front end of an oscilloscope near the at- tenuators so that the vertical amplifier can be driven through a coaxial cable. Before placing either video- amp fC in the circuits of Fig. 6, 7 or 8. adjust the 200-ohm off- set potentiometer (R7, R13. or Ri7, respectively) so that the voltage at the emitter of Q3 {a 2N3904) Is zero. That moves the video-amplifiers output into a "ballpark" operating region. In the frequency-counter pre- amplifier circuit Fig. 6. the off- set potentiometer R7 and the IK trimmer Ri 1 at 94 s emitter will var>' the threshold point of 9^* ^ so both must be adjusted to ob- g tain the best switching speed ^ and bandwidth, !8 For communications pur- jj poses, the circuit shown in Fig. 9: 8 can be modified once again to ^ that shown in Fig. 9. a DC- | to-20-MHz line driver. That type B of general-purpose amplifier | can be a variable-gain video dis- tribution amplifier or even a broad-band local-area network [LAN) line driver, R E 61 GET THE ^TEST ADVANCES IN ELECTRONICS WITH A SUBSCRIPTION TO wtMmncs* HWaHio SHOPPER cduntorl ^^M^ CABLE Find out how (t M^itui BLflUIA A csnvtrtiirnl tn>Liblnhc>ofh» ctifnputtr mof^l^n maiiuiTPioEiini juiAui&mtiisfmL ammsm fhcBWPC Radio-Electronics gives you exciting articles like: • ISDN: The Telephone Network of Tomorrow • The Facts on FAX • A Digilai Phone Lock • How To Design Switching Circuits • E(A~232 A real standard for senal interfacing? • Build a synergy card for your PC • ^386 Power at a 286 price • Build a biofeedback monitor • More on Multiplexing ENJO/ THE WORLD OF ELECTRONICS EACH MONTH! Now you can subscribe to the best elec- tronics magazine. The only one ttiot brings you articles on^^lectronics 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 you1l find helpful, monthly depart- ments such as Video News, Equipment Reports, Hardware Hacker. Audio Update. Drawing Board, Communications Cofner. All designed to give you instruction, tips, arid fun. FOR FASTER SERVICE CALL TODAY 1-800-999-7139 DON'T DELAY SUBSCRIBE TODAY! Just fill out the order card in this magazine and mail it in today. THE INSIDE STORY BYRON MILLER THERE IS A BATTLE RAGING. IT IS A battle to assume the role of stan- dard bearer for the PC hard-disk drive interface. The venerable ST'506 served the PC industiy well during its first decade, but as we move off into the 90 s with increasing reliance on high-per- formance 386, 486, and 586 systems, users demand ever- greater speed, capacity, and ease-of-use. Three technologies — ESDI, IDE, and SCSI— are vying to be- come the next standard- But how does a person choose among them? In this article we will examine the basic ideas and history behind each, compare and contrast their strengths and weaknesses, and point out situations where each would be useful. Backgi'ouxid Because each of the three new drive-interface standards repre- sents, tn some way, a response to the ST-506, let's begin with a little history and background on that standard. Properly speaking, the ST-506 was the model number iifi^ ^ ON HARD-DISK STANDARDS Decisions^ decisions^ decisions. Here we sort out the differences between today's competing disk drive standards. of a hard-disk drive that Sea- gate Technology Introduced in 1980. The capacity of that drive was a whopping five megabytes! Several years later, Seagate in- troduced a 10-megabyte mon- ster (the ST-412) with a similar electrical interface, and a new feature called buffered seeking that allowed the drive to "col- lect" sequential seek com- mands and then move the read/ write head across the surface of the disk in one quick, smooth motion. These drives recorded data on the disk platters using modified frequency modulation (MFM). The combination of recording method and electrical interface limited the maximum rate at which data could be transferred to and from the drive to five megabits per second (5 Mbps). By encoding the data on the drive in the run-length limited (RLL) format, designers could increase data transfer rate by 50% to 7,5 Mbps; capacity also Increased by 50%, The market continued to de- mand greater performance, so by spring of 1983, an ad hoc committee formed and pro- duced the first draft of a specifi- cation for a new drive interface, what later became known as the Enhanced Small Device Inter- face (ESDI]. By 1986, ESDI be- came a proposed ANSI stan- dard, and early in 1990, it became officially recognized as ANSI X3. 170- 1990, Development of the Intel- ligent Drive Electronics (IDE) interface began in 1984 when Compaq got together with West- ern Digital to develop an ST-506 controller that mounted directly on a hard-disk drive. The follow- ing year Compaq worked with Imprimis (now a part of Sea- gate) to integrate Western Dig- ital circuitry on a Wren disk 1 I J} 9- 9 m s a 63 Si c T3 a: 64 drive. Soon Compaq shipped the first PC with an IDE drive: other manufacturers followed suit shortly thereafter The ap* peal of IDE is that it eliminates one PC board and most of the Interface electronics required between a system bus and a hard disk, thereby sign ifican Ely lowering cost. Today IDE has pretty much displaced ST-506 as the standard drive Interface for desktop PCs. The Small Computer System Interface (SCSI) traces back to the Shugart Associates System Interface (SASIK which was de- veloped by the same company (Shugart Associates) and the same designer (Al Shugart] that developed the ST-506, In fact, Shugart developed SASi around the same time as the original ST-506. From the beginning, the SASI interface was designed to be more general than the spe- cialized interfaces heretofore developed for personal comput- er peripherals. Rather than using specialized signals to control various low-level hard* ware functions. SASI/SCSI in- cluded from the beginning a general-purpose 8-bit parallel bus and several control signals- The hope was (and still is) that a general-purpose bus would at- tract designers of various types of peripherals, SASI supported several im- portant features, including daisy-chaining drives and issu- ing high-level commands via a command block. Vendors quickly adopted SASI and be- gan to add features and func- tionality e,g,, support for Write Once Read Many (WORM) drives and other t>pes of devices. Sim* llarly vendors Increased the maximum number of devices from two to seven. They also added the ability to service sev- eral devices at once. After some evolution* the SASI interface be- came so popular that In 1986 the X3T9,2 ANSI working group adopted it as standard ANSI X3, 131-1986. or SCSI-1 for short. An enhanced version. SCSI-2, was finalized in 1990; it provides for wider bus widths and other performance-en- hancing features. With that background in mind, let's now look at each type of interface in more detail. ESDI basics ESDI is a disk-controller in- terface that is like an enhanced ST-506. For one. ESDI uses a similar cable and connector scheme: a 34-conductor control cable that is daisy-chained from drive to drive, and a separate 20-€onductor data cable for each drive. ESDI controllers typically support only two driv- es, even though the specifica- tion allows a maximum of seven. The signals on ESDI and ST-506 cables are similar but by no means Identical, so you can- not run an ESDI drive on an ST-506 controller nor an ST-506 drive on an ESDI con- troller Electrically, all signals arc TTL compatible: the max- imum length of an ESDI drive cable is nine feet, l^ble 1 com- pares signals from both of those systems. Another similarity between ESDI and ST-506 Is that ESDI is a device- level interface. In other words, its control signals direct low-level actions such as select- ing a drive head and moving it to a desired track on the disk. As well see. SCSI and IDE de- vices contain high-level inter- faces in which the operating system issues commands like, "Give me a block of data, as quickly as you can, and don t bother me with the details!'* The biggest difference be- tween ESDI and ST-506 drives Is the data transfer rate, which for basic ESDI drives runs at twice the ST-506 rate (10 Mbps), and which reaches its max- imum at 24 Mbps, As for disk formal. ESDI driv- es typically put about 34 sectors on a track (versus 17 for a stan- dard ST-506 drive), and they run with a 1:1 interleave. In operation on a PC, most ESDI controllers emulate stan- dard ST-506 controllers (e.g., the ubiquitous WD 1003), so no additional software drivers are required. IDE drives also emu- late the WDlOOa, but SCSI driv- es always require external software drivers. IDE The IDE interface strongly re- sembles the AT I/O expansion bus, as shown in T^ble 2. There are some important differences, and there is some inconsistency in the way different manufac- turers use some signals. For ex- ample, lOREADY can appear on pin 21, 27, or both, depending on the disk drive manufacturer Many new system boards con- tain a built-in IDE interface, so TABLE 1— ESDI AND ST-506 SIGNALS ESDI Signal ST*5a6 Signal Pin No. Head select Reserved 2 Head select Head select 4 Wrile gate Write gale 6 Confjg/status data Seek complete e Xfer Ack Track 0 10 Attention Write FauH 12 Head select Head select 14 Sector Pin 7 on data cable 16 Head select Head select 18 Index index 20 Ready Ready 22 Xfer reqoest Step 24 Drive sefect Drive select 26 Drive select Drive select 28 Drive select Drive select 30 Read gage Drive select 32 Command data OirecHon in 34 TABLE 2— IDE AT 1/0 BUS SIGNALS IDE sional AT I/O sional Dfk«u^ ri n tin n CS1FX- N/A I/O CS3FX N/A Chrp select for ST-506 compatible I/O DA0-DA2 SA0-SA2 Drive address bus lines DASP N/A Drive Active I Drive one percent DDO^DDIS SD0-SD15 Drive data bus DIOR^ -lOR Drive f/Q read DIOW- -lOW Drive 1/Q write DMACK- "DACKx DMAWQ acknowledge DMARQ DRQx DMA request INTRO IRQ14 Drive interrupt I0CS16- -i/ocsie Drive 16-bit I/O lOROY lOCHROY I/O channel ready PDIAG- ISI/A Passed diagnostics RESED- RESET Reset; on AT bus is opposite polarity. SPSYNC N/A Spindle sync. Produces clock for slave drives. there's no need to waste an ex- pansion sJot on a disk conLroI- ier Inexpensive IDE adapter cards arc also available for older systems. If you're not buying a preconfigured system, you must ensure compatibtUty between your intended controller and drivc(s). Electrically, an IDE drive connects to the controller with a 40-Gonductor ribbon ca- ble. Like ESDI, the IDE interface emulates a standard IBM hard- disk controller, and an IDE drive masquerades as one with a cor- responding value in the host system*s BIOS drive table. In- ternally an IDE drive typically has 34 sectors per track, al- though translation can make it appear to have 17, to match a BIOS table value. In addition, IDE drives usually operate at a 1:1 Interleave. You cannot change interleave, perform a low-level format, or run low-level disk utilities, for example the Norton Utility Calibrate. The controller electronics re- side at standard disk-drive I/O port addresses (1F0-1F7 and 3F0-3F7), and respond to all standard commands (formal track* read sector, write sec ton etc), as well as enhanced com- mands that allow more efficient operation. For example, com- mands C4 and C5 aUow the sys- tem to read and write multiple sectors, respectively However, most AT BlOS's do not yet sup- port the enhanced disk-drive commands. The IDE interface has evolved rapidly since 1984, occasionally with different vendors creating incompatible enhancements. Hence, in 1988 a Common Ac- cess Method (CAM) committee formed to define standards. By spring of 1989, the committee had produced a draft of an AT Attachment (ATA) interface standard. That document has evolved quite a bit over the years, and it is now well on its way to becoming an ANSI stan- dard, by way of the X3T9,2 working group. Like the ST-506, the IDE stan- dard allows a maximum of two devices on its shared bus. Drive 0 functions as the master, and drive 1 as the slave. Maximum cable length is only 18 inches, so the drives must be situated close together, SCSI SCSI is an intelligent system- level interface that, in theory, can connect through a common parallel 8-bit bus a variety of de- vice, including disk drives, op- tical scanners, printers, tape drives, network adapters, and various types of optical drives. It is an unfortunate fact of life that in practice, you'd probably end up installing a different SCSI host adapter for each type of de- vice in your system. (My main system currently has three SCSI adapters: hard disk. CD-ROM. and Bernoulii Box, — Editor) And it Is difScult if not impossi- ble to use a SCSI device intend- ed for one system (e,g,, a DOS- based PC) on another {e,g,» a Macintosh] system. The SCSI bus consists of eight data bits, a parity bit, nine TABLE 3^SCSI BUS SIGNALS Slgnal(s) Explanation DBO-7 8-brt bidirectional parallel data bus DBP Data bus parity line (optional) ATN Attention, used to send message to target when it lias control of the bus BSY Busy indicates that the bus is unavailable for use ACK Acknowledge, used by initiator for handshaking RST Reset, used to inrtiate a bus free phase MSG Driven by target to indicate that current transfer is a message SEL Used by initiator to setect target before command execution. Also used by target to reconnect when the reseleclion phase is implemented. C/D Control/Data, used during information transfer phases to transfer commands, status, messages, and data over the bus. REQ Request by target during information transfer phases. Handshakes with ACK to envelop data. I/O Input/Output determines direction of transfer during information transfer phases. controi Unes, and a line for ter- minator power^ as shown In 1^- ble 3. The bus can be driven with either single-ended or diT- ferential line drivers. In both cases, the bus has a total of 50 lines, A single-ended system al- ternates grounds with signals: in a differential system/ even and odd pins form differential signal pairs. Maximum cable length is six meters for single- ended and 25 meters for dif- ferential systems, SCSI devices on PCs and Macintoshes usu- aliy follow the single-ended standard. A host device issues a com- mand to a SCSI device via a 6- byte command descriptor block, which specifies an op code, a logical unit number and block address, a length control byte, and a control byte. The control byte has a feature that allows multiple SCSI com- FOR MORE INFORMATION For more mformation on disk -drive technologies, see these excelleni arti- des (pyblistied in Byto magazine): "The Evoluiion of ESDI.' June 1990: The IDE Hard Disk Drive inlerface," March 1991: 'The SCSI Bus. P^rt 1/ February 1990; 'The SCSI Bus, F^rt 2,;' March 1990. For detailed technical informalion on ANSI standards and technical commit- tee, contact the American National Standards Institute, 1430 Broadway. New York, NY 10018. (212) 642-4900. For printed copies of ANSI specifica- tions, contact Gfohal Engineering Docu- monts, 2605 McGaw Avenue, In/lne, CA 92714, (800) 854-7179, (714) 261-1455. Eleclronic copies (including working draJts) of SCSI and many related stan- dards are avaifabie from the SCSI BBS. (316) 636-8700. 300-9600 bps. 8N1, For producJ information, contact Con- ner Peripherals Inc. 2221 Oid Oakland Road. San Jose. CA 95131; Mtcropolis Corp. 21211 Nordhoff Street Chaisworth, CA 91311: Seagate Technology Inc. 920 Disk Drive Scotts Valley CA 95066^544.— Editor mands to be sent in a singie block. Every SCSI command re* turns a stains byte, each bit of which has a specific meaning (good, busy* elclL Most devices currently on the market adhere to the SCSI-1 standards. However many neu^ devices conform to SCSI-2, which offers much greater po- tential performance. Whereas SCSI-1 allows a maximum of 4 million transfers per second » SCSI-2 allows 10. In addition, SCSI-2 increases maximum bus width from the 8-bit SCSI-1 standard to an optional 16 or 32 bits. The X3T9.2 committee completed the SCSI-2 specifica- tion in August 1990: after edi- torial polishing* it should be published sometime in 1992, (The committee has also begun work on another standard, SCSl-3.— Edifor) SCSI can communicate with several different devices simul- taneously For example, an SCSI host can disconnect from a tar- get device after issuing a com- mand, connect to a different target device, give it a com- mand, disconnect from it. and then reconnect back to the orig- inal device. By contrast, IDE op- erates in a master/slave mode in which the interface can issue only a single command at a time. To use an SCSI device in a PC requires BIOS -level software drivers, tspically added through adapter-based EPROM or a de- vice driver loaded at boot time. The Macintosh has a built-in SCSI Manager SCSI compatibility is still a problem. Although electrically identical, SCSI peripherals from different vendors may be dissimilar In other words, an SCSI drive from vendor A may work fine with a given SCSI adapter, wliile an SCSI drive from vendor B does not. That is due to variations in interpreta- tion and implementation of the SCSI command set. Hundreds of commands are available, some of which work differently with different types of devices. For example, one form of the write command can be used for writing to a Direct Access De- vice (DAD) and another for a Se- quential Access Device (SAD I One vendor can interpret a disk drive as a DAD where another would interpret it as a SAD. Sending a SAD write command to a DAD device will not work. In response to that dilemma, the CAM committee has defined a standard subset of SCSI com- mands that performs basic functions (read, write, etc.). The resulting eleven commands are known as the Common Com- mand Set (CCS), and are part of the SCSI-2 standard. Compare and contrast Like ST-506, ESDI is an unin- telligent device-level interface that transfers data serially from drive to controller, which com- piles serial bits into 8-, 16-, or 32-bit chunks of data and pre- sents them to the host. IDE and SCSI devices, by contrast, build up data b>ies on the drive and present them to the system in 8-, 16-, or 32-bit chunks. The advantages are several; less-ex- pensive controllers and adapt- ers, less cabling required, more reliable performance, and high- er performance, IDE drives (even with an adapter, if required) tj^ically cost less than SCSI and ESDI drives of comparable capacity and performance. However, a given system can hold a max- imum of two IDE drives, where- as seven SCSI devices can be handled directly, and the- oretically thousands Indirectly ESDI controllers typically allow only two drives, and there is no pretense of supporting other types of devices. Both IDE and SCSI drives suf- fer from various types of com- patibility problems that make system integration trickier than it should be. Recommendations Selecting a drive interface de- pends on your performance needs, capacity needs, budget, and future system migration plans. If cost is the main deter- minant, youll probably want to go with IDE, If performance is paramount. ESDI or SCSI will be your choice. Remember that performance you don't need right now may become neces- sary in the future. Sometimes a little added expense turns out to be a good investment. If you need a really large drive, ESDI or SCSI will also be required. 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B as i t tel e [ihon e 1 1 se cou- pled with the user's understanding that someone may be listening or a'Cording vital data and information greatly reduces the opportunity for others to purliiin mca n i ngfti I i n form at ion . CLAGGK L\C. P.O. Box 4099 ' FaniiingdaJe. NY 11755 VW^M' ru^ili my c' nf %\w ( JtLiiiitTMiirv-rillJimx' IVLimiqiit'^ Vid^ii VMS C^N^^iic U>f ji ictul ktvHt III sS5.<)^ nch . \:i I lit tlijAftio onlrtnl _ Atiumnt t*r paymcni S Sjk * 141 (S V S. iKiIy) Eapfrr Hair / All iMyiUPfti* fn WS h- fiifldv Cjiudkufts MM » I «J y^f VHS Tlic professional discussions seen on the TV screen in yt^ur home rc-vcals how to detect and disable wiretaps, midget radio-frnjucncy tmnsmrtters, and (Jther bugs, plus when to use disinformation to confuse the unu^inted listener, and the K^chnique of voicc scrambling telephone communications. In fact, do you know how to Utok for a bug, where to look for a bug^ and what to do when you find ii^ Dugs tjf a ver)' small size arc easy to build and they can be placed quickly in a matter of seconds, in any object or nxim, Ibday you may h;ive used a telephone handset that was hugged. It pnibably contained three bugs. Cine was a phony bug to f(K>l yuu into lx;lieving you found a bug and secured the telephone. Tlie sec- ond bug placates the investigator when he finds the real thing! And the third bug is found tmly by the professional, wiio continued to search just in case there were more bugs. The professional ts not without his ttx)ls. S(x*cial equipment lias been de- signed so chat the professional can sweep a r(M>m so that he can detect voice-acti- vated (VOX) and remote -activated bugs. Some m viewing the video tape in the pri- vacy of his home. After you review the video cart:fully and understand its con- tents « you have taken the first important step in either acquiring professional help with your sur^'eillance pmblems, or you may %"ery well consider a carcxT as a coun- tersurvciilance professional. The Dollars You Save ^obtain [he information contained in the video VHS cassette, you would attend a professional seminar costing $350*750 and possibly pay hunda^tls of dollars moa' if you had to travel to a distant city to attend. Now, for only $^9.95 (plus $4.00 P&H) you can view Coantersnr- tic ilia rice Techniques at home and rake refresher views often. To obtain your cojiy, complete the cou prGnce (Apple) 19.50 Real World Postscript (Roth) 22.50 POSI Sc r rpl V i s u 3l A p p r 0 ftCh (Smllh} 22. SO Tllknkiftg in PostScript |Rejd) 22.50 U nd St PS P g rmm g (No Itigang} 25. 50 The Wh ote Works ( atl Po stScripl ) 349. S0 SOOK-ON DEMAND STUFF Book-on-demand resource kit 39. SO GEnle PSftT sampler (Ile/Mac/PC) 39.50 Fft€E VOICE HELPLmE VISA/MC going to grant the true believers that sonfiething weird was in fact going on, then Ockham s razor reduces it NEED HELP? Phone or wrile your Hardware Hacker questions directly to: Don Lancaster Synergetfos Box 809 Thatcher, AZ 85552 (602) 428-4073 Brookstone 127 Vose Farm Road Peterborough. NH 03460 (603) 924-9541 CIRCLE 3D1 ON FREE INF OFIMATION CARD Harriet Carter Slumps Road North Wayles, PA 19455 (215) 361-5151 CIRCU 302 on FHEEiNFOflUATlON CARD Comb Corp 720 Anderson Avenue St Cloud, MN 56395 (800) 522-3035 CIRCLE 303 ON FREE INFORMATION CAHD Crutclifield 1 Crutdifield Park Charlottesville. VA 22906 (BOO) 336-5566 CIRCLE 304 ON FREE tNFORMATtON CARD DAK 8200 Remmet Avenue Canoga Park, OA 91304 (800) DAK-0800 CIRCLE 305 ON FREE INFORMATION CARD Damark Box 29900 Minneapolis, MN 55429 (800) 723-9000 CIRCLE 306 ON FREE INFORMATION CARD 47th Street Photo 36 East 19th Street New York, NY 10003 (800) 221-7774 CIRCLE 307 ON FREE INFORMATION CAHD Harbor Freight 3491 Mission Oaks Blvd Camarillo. CA 93011 (800) 423-2567 CIRCLE 30a ON FREE INFORMATION CARD Hello Direct 140 Great Oaks Blvd San Jose. OA 95119 (800) Hl-HELLO CIRCLE 309 ON FREE INFORMATION CARD down to "sparks may lengthen bat- tery fife/* That might bear further looking into as a hacker topic. An ordinary flashlight cell does not yiekJ all of its chemical energy v^henever it "runs down," Clearly, if so much as a tiny scrap of the zinc case remains, then recoverable chemical energy might still remain — at least in theory. In- stead, a cei! will polarize and thus raise its series resistance to the J&R Music World 59-50 Queens-Midtown Express Maspeth, NY 11378 1800} 221-8180 CIRCLE 310 ON FREE INFORMATION CARD Micro-Mark 340 Snyder Avenue Berkeley Heights. NJ 07922 (800) 225-1066 CIRCLE 311 ON FREE INFORMATION CARD Northern Hydraulics PC Box 1499 Bumsville, MN 55337 (800) 533-5545 CtRCLE 312 ON FREE INFORMATION CARD Porter Camera Box 628 Cedar Falls. lA 50613 (800) 553-2001 CIRCLE 313 ON FREE INFORMATION CARD Quill PO Box 50-050 Ontario. CA 91761 (714) 988-3200 CIRCLE 314 ON FREE INFORMATION CARD Real Goods 966 Mazzoni Street Ukiah,CA95482 (800) 762-7325 CIRCLE 315 ON FREE INFORMATION CARD Tandy Leather 1400 Evenrtan Parkway Ft Worth, TX 76140 (817) 551-9770 CII^CLE 316 ON FREE INFORMATION CARD Taylor Gifts 355 East Conestoga Road PA 19087 (215) 789-7007 CIRCLE 317 ON FREE INFORMATION CARD JC Whitney 1917*19 Archer Avenue Chicago, IL 60680 (312) 431-6102 CIRCLE 31 B ON FREE INFORMATION CARD DYS AND OTHER RESOURCES SYNERGETICS BOK S09-RE Thatcher, AZ 85552 (60a} 428-4073 CmCLE Bl ON FREE INFORMATIONt CARD point where it can no longer deliver useful power What if you recycle a fraction of the power back into the cell as a high-current pulse? Lets say we put in ten amps for ten mifliseconds per second for every continuous one amp out. Could that partially delay the increase of cell resistance by slowing down the polarization pro- cess? Or maybe just warm the eel! up to a more optimum power deliv- ery point? Note that electfoplaters do this all the lime. They occasionally reverse the plating process and pur- posely unplate for a while. That im- proves the smoothness, and does other good things to the finish. The obvious questions to ask here are "Does energy recycling help us at all?." "What are the op- timum recycle pulse strengths and best duty cycles?," "Does any higher frequency AC help?." and. of course. "Even if all these effects do significantly improve life, are the economics there?"' Let s have your thoughts on this. Cell energy recycling does look like a reasonable and legitimate re- search topic. But as a warning, if you're going to experiment, keep your target carbon-zinc cells in a suitable 'bomb shelter/" And be cangful. Microcontrollers. The breakeven point between using and not using a CPU and RAM-ROM-l/0 architec- ture in any hacker project was passed a decade ago. Ockham's razor says that it s now ridiculously faster, cheaper, and far better to in- clude a microprocessor these days, rather than foolishly trying to leave one out. Yet. I gel all of these strange calls for projects that require such things as keyboards, displays, fancy tim- ing, strange sensors, and minu- scule markets. All of which could be done insanely faster and cheaper by first making a model with a $30 Commodore 64 from a yard sale and then, if really needed, working out a one- or two-chip RAM-ROM-1/ O solution. Besides lots of really great micro- controller projects found right here in Radio-Electronics. you1l find lots of others over in Steve Ciarcia s Circuit Cellar hk. And I do offer my NAMES AND NUMBERS Analog Devices One Technology Way Nonfood, MA 02062 (617) 329-4700 CIRCLE 319 ON FREE INFORMATION CARO Avery Dennison 818 Oak Park Road Covina, OA 91724 (818) 915-3851 CtRCLE 320 ON FREE INFORMATION CARD GEnle 401 North Washington Street Rockville. MD 20850 (800) 638-9636 CIRCUE 321 ON FREE INFORMATION CARD Intel 1000 Business Center Drive Mount Prospect, IL 60056 (800) 548-4725 CIRCLE 322 ON FREE INFORMATION CARD Kleerdex PC Box 3248 Aiken, SC 29801 (800) 325^3133 aRCLE 323 ON FREE INFORMAHON CARD Pioneer Box 1720 Long Beach, CA 90801 (213) 835-6177 CIRCLE 324 ON FREE INFORMATION CARD Redmond Cable 17371-Al NE 67th Court Redmond, WA 98052 (206) 882-2009 CIRCLE 32$ ON FREE INFORMATION CARD Rohnn Box 19681^631 Irvine, CA 92713 (714) 855-0819 CIRCLE 326 ON FREE INFORMATION CARD Snaptron 1714 Topaz Drive Loveland, CO 80537 (303) 663-2820 aRCLE 327 ON FREE rNFORMATlON CARD Sony 9 West 57th Street, 43rd R New York, NY 10019 (212) 371-5800 CIRCLE 328 ON FREE INFORMATION CARD Synergetics Box 809 Thatcher, AZ 85552 (602) 428-4073 CIRCLE 329 ON FREE INFORMATION CARD WSI 47280 Kato Road Fremont, CA 94538 (800) TEAM-WSl CIRCLE 330 ON FREE INFORMATION CARD Micro Cookbook land Micro Cook- tMDok 11 that can get you started on nnany of the fundamentals. Wireless broadcasters One of the less pleasant recent hacker surprises is that most low- cost FM winsless broadcaster cir- cuits flat out will no longer work. Older analog FM radios could be tuned anywhere across the entire band and had a very strong AFC or automatic frequency contml circuit that would lock onto a non-standard signal and track it anywhere. But nearly all of todays digitally syn- thesized FM receivers Cespecialiy most car radios) absolutely demand that the transmitted signal be pre- cisely locked onto one of the FM broadcast channels. Designing any high-quality FM transmitter that is both ultra-stabJe and able to be rapidfy and linearly frequency modulated gets tricky fast because you are asking for a circuit that both will and will not change its frequency. The **tech- nically correct" high-end solution is to use an indirect circuit known as the frdquency lock hop. The aver- age output frequency from your transmitter gets divided down with a counter and compared against a crystal reference. An error signal is then derived phase-lock-toop style and used with varactor diodes to continuously force your transmitter back onto the connect frequency Hams have long chosen a simpler technique called crystal pulling. Your average crystal is slightly sen- sitive to reactive loading tn a circuit. The rule of thumb is that you can pull a plain old crystal around one-tenth percent But crystal pulling ts usu- ally highly nonlinear. To pick up enough deviation, hams would start off with a low-fre- quency crystal and then multiply up into their final 145 megahertz — or whatever frequency range- Typtcal hams rarely concern themselves with any wide-deviation bn^adcast- quality audio. In fact, they are not allowed to do so. Apparently both Sony and Roneerhave figured out how to lin- early pull a special third-overtone HF crystal to directly let you do a full CD-qualtty FM stereo transmitter that is precisely locked onto the cor- rect frequency. Sony s product is called the XA-7A, and Pioneer's is the CD-FM-1, While the intended use of those units is to let you con* veniently add a CD player to your car radio, either one will apparently make up most of the critical circuitry for an excellent and very high-quali- ty FM stereo wireless broadcaster Dealer cost for the units is in the $42 range, and they seem to be easy and fun to hack. They offer both on-channel lock and near- broadcast quality We will look at the P/o/?eer CD-FM-1 here. Obvious uses for a short-range FM broadcaster include "Ptease buy my house" messages for dnve- bys; baby sitting or handicapped monitoring; and cord-free audio for a teacher, a public speaker, or a vid- eo actor But there are also zillions of non-obvious uses, including such things as getting data onto or off of a rotating shaft, and short-range rocket telemetry. Limited-range and limited-power FM broadcasters are now generally allowed by the FCC. while the more powerful units have to meet specific licensing and certain type-approval requirements. More details on get- ting and meeting FCC specs appear in our Hardware Hacker III reprints. Both the unmodified Sony and Roneer seem to have been created with full FCC compliance code in mind. I could also see several wired or semi-wireless broadcaster applica* tions that might use twin lead to route high-quality audio all over your plant or whatever With wires, you could easily go several hundred feet without running afoul of FCC speci- fications* all the while avoiding the hum and noise problems of using "real" audio. And a whole new world of point-of-sight iight-modufated FM data links is also newly opened up In their intended use. you unplug your car radio antenna, plug in the CD-FM-1 , and then reconnect your antenna, A DIN-S connector goes to your CD player and the usual red wire goes to your + 12-volt battery. When your CD is turned on. its audio appears at 88,1 on your FM dial AJl other stations are muted. That quickly and conveniently lets you use your existing car audio sys- tem without needing anything fancy Len iudio input 1 Preemphasis FM reactance Buffer and Stereo rriux gen and drtvf r mod/osciiiaior tr^-'^pass (filer tCl. XI 01. 02 Dl, 03. X2 Ci. BPFl Hlqhi audio input +T2 vdc input i Svvitchable 1,4 volt dc Changeover Pft-regulaior PosHegulatof relay drtver 0S,Q6JC2 QB 07. D4 Ata anicU input RG. 2— MOST LOW'EHD FM WIRELESS BROADCASTERS simply will no longer work because nearly aU the newer synthesized ri^eivers now tfemantf precisely on-channel stations. The Pioneer CD-FM-1 (block diagram shown here) generates exact-frequen- cy stereo FM signals. The CD*FM-1 is easily made wlreless- in the way of rework or switches. A block diagram of this matchbox- sized module appears In Fig, 2. while an approximate and un- official schematic is shown in Fig. 3. Because of the surface-mount parts used, certain component values are based only on my estimates. The exact circuit shown also might not be fully accurate. At first glance, the circuit seems deceptively simple. But if you flip the board over, you'll find nearly a dozen more surface-mount semi- conductors on the foli side. It is ob- vious that bunches of time and effort went into the design. As with any circuit you usually want to start off with your power distribution. The twelve volts from the car battery turned off and on by an auxiliary CAUX) logic signal The power is applied only when your CD is to be used. The power switching is via input-switching field-effect transistor Q5 and series power driv- er 06^ Driver Q6 is followed by a two-volt regulator IC2. which in turn is followed by a dynamic regulator or capacitar^ce multiplier at Q8, The post-regulator will obviously intro- duce a temperature drift that might or might not be intentional Several refinements in the supply switching include Zener diode D2 to prevent turn-on with a weak battery or during cranking. The network R27-C30 gives a slight tumoff delay to eliminate clicks or thumps. Except for that switchover relay the nest of the circuit runs on the dynamically regulated 1,4-volt sup- ply Theoretically, a single AA cell could be used instead. The heart of the circuit is the great Rohm BA-1404 FM stereo broadcaster chip that we have looked at in the Hardware Hacker H reprints. Only this time, the internal RF transmitter circuitry is not used and gets very carefully deactivated. A 38-kH2 signal CXI) is needed to modulate the incoming audio and to create the 19-kHz pilot signal. Con- trol VRl adjusts your balance, and VR2 sets the 19-kilohertz pilot level The multiplexed audio output is added to the pilot and routed to a combination driver and pre- emphasis network via and Q2. The amount of high-frequency pre- emphasis is adjusted by TCI . The linear and broadband "crystal puller" is an interesting reactance modulator scheme using a pair of varactor diodes at Dl. A simplified circuit of the modulator appears in Fig. 4. What you've got is a crystal in series with the parallel resonant cir- cuit "A," which is, in turn, in series with a second resonant circuit "B/' Tank 'A" is tuned well below the crystal's parallel resonance and will normally appear as a high inductivB reactance. Tank "B" is tuned above the crystal parallel resonance and will appear as a capacitive reac- tance. In the absence of any audio 9 =lrom +1,4 volt rogyiatect supply OB 2.2 tiH LI R1 LEFT 12K AUDIO ©-VM- INPUT GROUND 0Hl RIGHT AUDIO INPUT LAMP AUX to C0I radio t amp In +t . 4 vdc .22u C24 From 12 V battefy WARNING: Ba sur? to current llnitt the AUX Input wflh an eternal 1 K reslitor! Fia 0— APPROXIMATE SCHEMATIC of the Ptoneer CD-FM-1. WhHe Inlended as a CD- aijcllchto*car*fad[o adaptor, this module can easily become a highly stable and on- channe! FM stereo wireless broadcaster. Applying * 12 votts to the AUX Input acti- vates the module. modulation, the reactances will can- cel, and the series combination of the crystal and the two tanks be- comes a high-impedance open cir- cuit. Those varactor diodes act as electnonicalty variable capacitances that raise or lower the tank frequen- cies. On positive modulation swings, both tanks fncmase their resonant frequencies; on negative swings frequencies decrease. The final result is a reactance fre- quency modulator whose resonant frequency is set by the crystal but it is rapidfy shif table either way by the multiplexed audio. Usually a fre- quency change varies as the squafB root of a capacitance change. But. because a pa/rof varactor diode ca- pacitors is changing, the resonant frequency changes linearly Yiilh the modulation input. At any rate, 0^ is a P/erce- style oscillator that can oscillate at the frequency determined by the high- est impedance sum of the crystal's third overtone resonance and the reactance modulator tanks. A fine- quency of 88 J megahertz is used in my particular sample, with a firial trim grven by TC2, The fundamental crystal frequen- cy is way down at 29.7 megahertz, but the oscillator tries its best to run at 8SA. The resultant waveform thus has some uneven subharmonic lumps- It IS very important to keep the loading on any FM oscillator con- stant, especially when using an overtone crystal. So, a buffer and driver transistor follows at QA. That in turn drives a special bandpass filter (probably a surface acoustical wave, or a SAW device) to eliminate any subharmonics and out- of- band harmonics. Only the crystals third overtone at a frequency of 88.1 MHz is allowed through the filter Even with the attenuation through the bandpass filter, the output signal is still too strong to directly couple into an FM receiver's antenna, so it is further attenuated by R20 and Recall that the supply power is turned on only when you want to listen to your CD player When the 1 .4-volt DC supply voltage is pres- ent, relay-driver QA and spike-sup- pressor D4 pull in the relay, connecting the RF-converted CD audio directly to your auto-radio an- ^ tenna input. At the same time the i antenna is disconnected to prevent g any back radiation or unintentional N broadcasting. You do. of course, ^ also have to pushbutton select 88.1 | MHz on your car radio to listen to ^ the CD audio. | Once again, this description is for 3. the FM-CD-1. 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The third overtone PARALLEL RESONANCE of the crystal is at the desired FM channel frequency. TANK A resonates ABOVE the crystal's frequency and appears as a high INDUCTIVE reactance. TANK B resonates BELOW the cry stars frequency and appears as a high CAPACITIVE reactance. The AUDIO MODULATION uses a pair of VARACTOR DIODES to vaiy these capacitors. FIG, 4^SIMFyFIED SCHEMATIC of the linear reactance modulator. Hacking the CD-FM-1 In the absence of a CD player, the CD-FI^-1 can be acti\^teci by con- necting the Aux input to the +12- volt supply. Your left and right audio inputs are normally at "line" level; additional gain will be needed for most microphones. Any and all aud- io connections must be shielded. The antenna changeover relay might be optionally defeated by shorting R23, Supply current is 30 milliamps with the relay active and 17 miliiamps with it defeated. An- other four n^illiamps can be saved by disconnecting the aux input and shorting the collector to emitter on Q6. Nearly another milliamp can be saved by removing R22. The re- maining power needed by the " useful" part of the circuit is then L4 volts at eleven milliamps, or something around fifteen milliwatts. With those power reductions, you could probably substitute an ordi- nary 9-volt transistor battery for your 12-volt supply But be sure to turn the power off when you are not using the transmitter. Theoretically you might want to replace the dynamic regulator 08 and substitute a single AA cell in- stead, A bypass capacitor or two would afso be a good idea if you try that. One way or another, though, you can easily get the circuit down into the mtllipower range but not the micropower range. A possible antenna takeoff point for any low-level direct-broadcasting experiments seems to be the col- lector of O^- Figure 5 shows how to route a 30-inch antenna wire through a gnommet in the case. ! got a 50'foot useful range with a good car radio that way. Be sure to insu- late the wfre tip to prevent possible shorting of the DC supply or damaging of the filter A far cleaner but weaker takeoff point would be the pin -4 filter output. While the BA1404 supply voltage can be raised as high as 3 volts, doing so may change the perfor- mance of the reactance modulator The best way to increase the range is to improve the antenna on your receiver Be sure to connect a good receiving antenna and discon- nect any cable connections. Experi- ment with the antenna orientation: vertical might be best for car radios and horizontal might work out better for a home hi-ft. The range can also be improved by placing a ground plane, such as a grounded cookie sheet Cor prefera- bly something bigger), under your transmitter That could give you a hemi pattern with double field strength. A directional receiving antenna^ such as a correctty cut Yagi. can also dramatically improve your range. Note that lower power plus good antenna matching and orientation will give you vastly more range than will htgh power and poor or im- properly aligned antennas. CIRCLE 2Q3 OH FREE INFORMATION CARD While there rs that extra booster amplifier remaining unused in the BA1404, it might be tricky to access and still have it remain stable. An external boost circuit could also be built using a 2N918 transistor or something similar That would best be done in a separately shielded and a properly decoupled box. Do not. under any arcumstances, at- tempt to amplify the unhltered out- put. Doing so will create unaccepta- bly strong outband signals es- pecially at 29.7 megahertz. What can you get away with in the way of increased power? Any boost at all gets you into a legal gray area. But. as a practical matter if your DC input power to your boost stage is under 50 milliwatts, and if nobody complains, and if your total useful range ts well under a hundred feet, and if you use the transmitter your self rather than selling it to some- one else, you can probably get away without any serious problems or hassles. On the other hand, using one of these as a predriver to broadcast heavy metal to your entire college campus is a very big no-no. Another contest or two This CD-FM-t is one of the most hackable projects to come down the pike in a long, long time. For here we have all oF the compact and millipower core circuitry needed for one very high-quality and quite sta- ble FM stereo Cor mono) broad- caster all in one place and ready to go — with the nasty stuff fully debug- ged. And one that works with syn- thesized auto receivers. For our first contest this month, just tell me about a new or unusual use for a short-range and high-quali- ty FM stereo or a mono wireless transmitter Or show me a variation on the circuits we just looked at. There will be all of those usual incredibie Secret Money Machine it book prizes going to the dozen or so best entries. In addition there will be an all -expense paid (FOB Thatcher AZ) tinaja quest for two going to the very best of alL Be sure to send your written en- tries directly to me here at Synergetics per the help box. rather than on over to Radio-Elec- tronics editorial. Thirty inch vtrtical vvire II II new V Z Z i RG. S— AN ANTENNA CAN BE ADDED as shown to the CD-FM-1 for your initial short-range FM broadcasting experi- ments. Be sure to fnsufate the far end of your coupling gimmick. Experiment to get the hest length and orientation, DYS resources I thought we'd do something a tad unusual for our resource sidebar this month. There's a group of di* rect-mail outfits that I will call DYS, short fof DistfBSsed Vuppy Surplus. All these folks specialize mostly in overpriced toys for the non-tech- nical types. But every once in a while, an electronic gem or iwo shows up at a really unbeatable price. Or a useful tooL Or a great idea. An example or two- Those "meals m minutes " food vacuum- packaging machines seemed to bomb out as a Yuppy prize. Their intended use was to package sin- gle-portion leftovers so they can be frozen, boiled, or nuked. And they are great for just that. But at $29 each via DYS, they also make very effective software and book vac- uum-packing machines. Be sure to get the type that has the little elec- tric pump with it. Plain ofd Baggies work just fine with them. Those automated bread ma- chines also bombed at retaiL This happened because far too many femates viewed them as an outright threat and they throw both the ma- chine and whoever gave it to them out of their houses. So 1 got one via DYS. Around here these days, any bnead that is even twenty minutes old is considered "stale/* and even the birds won t touch it. You do have to be selective. For instance, a CPM computer is pretty much worthless at any price, as rs any laser printer that does not speak real PostScnpt or for that matter any teletext receiver with no teletext to receive. My three favorite DYS sources are Dale, Comb, and Damark. But every once in a white, a good solu- tion to a technical problem can even be found rn such unlikely sources as Taylor Gifts or Harriet Carter. I thought I had a lot more of these DYS catalogs than I could hnd at column deadline time. Is JSM still around? They invented DYS in the first place. How about the Sharper image folks? So why don I you tell me about the rest of them? As a second contest, just tell me about any non-obvious direct-mail resource that can be used to get ideas and solve hacking and other technical problems. Include a sam- ple copy if you are able to, I've also added a great heaping bunch of other unusual drrect^maif sources to our sidebar While sev- eral of these are clearly not DYS. they do offer very interesting and very useful catalogs. And every hacker should definitely know about them. New tech lit From Analog Devices, the fat new Data Book Voiume tO on their ana- fog integrated circuits. From WSt, there's a new Programmable Pe- ripherals Design and Applications Handbook that includes lots of free demo software. From InteL you can get their new PLD shell Plus pro- grammable logic design and its su- pervision software. It is free on a professional request. Assorted free samples of Kydex thermoplastic sheets are obtainable from Kleerdex, This stuff looks great for custom thermoformed cases and enclosures. There s lots of colors, thicknesses, and surface finishes. And free tactile dome key- switch samples are available through Snaptron. Finally* Avery De- nnison now has test- fixture samples of their FasTape UHA super-strong clear adhesives. A reminder that I still have lots of book-on-demand bound reprint continued on page 88 AUDIO UPDATE Testing the testers: Another exceptional paper from the 31st AES convention LARRY KLEIN Conventtonaf listening tests have always been problem* aticat for dedicated au- drophiles. By "conventional." I mean tests posing as scientific with such nnethods as double-blind tech- niques, careful controls, statistical analysis, and instant switching with precise level equalization. The edi- tors of The Absolute Sound. Ster- eopNte, and other non-mainstream audio publications believe that those techniques obscure the sound quality differences that they hear so easily when listenmg under relaxed conditions. i.e.> where an audio component is listened to for hours, days, or even weeks to evalu- ate its sound quality, and then its sound is compared to that of a refer- ence component under similar lis* tening conditions. If quality dif- ferences heard during this long- term audiophile testing fail to ap- pear under the tightly controlled "quick-switch" procedures, then, in their view, the purportedly rigorous scientific procedures (espoused by people such as myself) must be somehow flawed and thus terribly misleading. Incidentally, it's worth pointing out that the contention between the two opposing camps seldom Is re- duced to determining which of two amplifiers sounds better Instead, the argument is usually about whether properiy operating modem ^ amplifiers sound alike or different. ^ If. as claimed by most au- § diophiles. carefully performed ^ switching tests based on double- ^ blind techniques fin which neither § the tester nor the listener know the S identity of the components being o compared) are of dubious value, its "g important that those involved in ^ new-product and new- technology evaluations know that their tools are flawed„ David L. Clark. ofABX fame. 76 discusses these matters and more in the Audio Engineering Society preprint. Ten Years of ABX Testing IDavid L. Clark (3167 K-Dl About ten years ago, David Clark and his associates invented the ABX switch, a sophisticated com- ponent that enables a listener to do double blind listening evaluations without the need for a second or third party to handle the random switching involved. The ABX switch automatically charts a listener s judgment about whether compo- nent A or B is the same as X, which might be A or B in a given trial se- nes. At the end of the test series, the number of correct decisions is given. When it became available. Clari< and his associates thought that the ABX comparator would be a power- ful tool for determining, once and for all. whether small differences in components such as power ampli- fiers are audible and commonly heard- However, the debate raged on as though the ABX device were never invented. When the ABX comparator confirmed that au- diophile listeners consistently fail to identify components on a basis of sounds that they thought they heard, the audiophiles were not em- barrassed. Most convinced them- selves that they heard those differences clearly under normal, not test, listening conditions. Audiophiles offered tvsro explana- tions for their failure to discern acoustic differences during ABX testing: CI) The switching relays and connectors used in the ABX switch intnDduce artifacts that somehow mask the differences, and C2) short- term, quick-switched listening does not permit differences that are read- ily apparent on typical long-term au- diophile testing. In other words, the stress induced by a rigorous test de-sensitizes the listener and im- pairs his ability to hear differences that are apparent under more relax- ed circumstances, Clark set out to test the reality of the explanations and excuses. Two audiophile societies participated: The Audiophile Society CTAS). con- sisting mostly of true believers in high-end audio equipment and Clark's group, the Southeastern Michigan Woofer and Tweeter Marching Society (SMWTMS) who tended to be rationalists. The test consisted of the inser- tion/non-insertion of a black box non-linear circuit that injected 2.5% harmonic distortion into the signal path. Two sets of tests were planned for each group. One em- ployed the ABX switch for the typ- ical quick-swjtch procedures pre- ferred by the "scientific" audio group, while the other called for the long-term listening preferred by the high-end, everything-sounds-dif- ferent crowd. As might have been predicted, the "golden ears" of the TAB group refused to have the signal passed through the ABX comparator and instead used a much slower man- ually plugged 16*trial comparison test with a very expensive high-end system familiar to most of them. The SMWTMS group listened in an unfamiliar room to an unfamiliar sound system. Double-bfincJ black boxes The second part of the test at- tempted to set up the long-term, relaxed listening situation favored by high -end audiophiles. Ten sealed black boxes were distributed dou- ble-blind to at least 16 members of each group. Half of the boxes con- tained the distortion circuit; the others were simply bypass circuits. Participants were instructed to patch their black boxes into the tape loops of their home pneamplifters and listen for as long as rtecessary to decide whether or not the black box was neutral. No one in either group was able to distinguish the distorting box from the non-distortmg box reliably (n long-term listening on a home system. Moreover, no one in the TAS group could identify reliably the distorting black box in the manually patched series of relatively quick tri- als. However, with the ABX com- parator, the SMWTMS group was able to differentiate between the distorting and non-distorting black boxes within 45 minutes. And they went on to perform just as well with the black box at even lower distor- tion levels! This, to my mind, constitutes an ultimate rebuttal to those who claim that long-term listening is required for detecting differences, and that instant switching with boxes such as the ABX comparator somehow masks acoustic differences, To re- peat: the Audiophtle Society failed to detect the 2.5% total harmonic distortion (THD) under its preferred listening conditions. By contrast, the SMWTMS group, using the ABX switch, detected the distortion quickly and, later, at even lower lev- els. Those who have been involved with ABX testing agree that the rea- son for the high sensitivity of the ABX procedure is the ease and speed of the comparison, which en- ables one to focus on the detection task. Dependence on one's memo- ry of what one thinks one heard — interrupted by juggling cables white switching components— obviously does not make for reliability in eval- uating components, despite au- diophile claims to the contrary. Final note People I consider to be fuzzy- minded, non-technical elitists are not the only ones who believe that rigorous double-blind testing obscures small audible differences under non-test conditions. When Clark was chairman of an AES Workshop on Esoteric Audio in 1988. he asked the audience to indi- cate by a show of hands whether they believed that different modern gain-matched power amplifiers sounded different from each other Clt was assumed that all of the ampli- fiers would measure up well in con- ventional testing, and be operated within their ratings J Approximately 70% of the AES audience indicated that they thought the amplifiers would proba- bly sound different! Along with Clark. 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NO EXPENSIVE INSTRUMENTS: Home study course shows you how to make good money in VCR repair. An amazing fact: you can do more than four out of five VCR repairs with ordinary tools and basic fix-it proce- dures. Our home study pro- gram shows you how. Learn all of the systems, mechanisms, and parts of almost all brands of VCRs, With no expensive instru- ments. Ab complicated elec- tronics. No fancy workshop. The step'by-step texts and close personal attention from your instructor make learning easy. Texts, course materials, and tool kit are sent to your home. Graduate ready to make up to $50.00 or more per hour in your own spare-time or full-time business. Send today for your free career tiool(tel. Or call 800-223-4542 Name Address. City.. . Stale - Zjp_ The School of VCR Repair 2245 Perimeter Park, Dept. VG342, Atlanta, Georgia 30341 ASK R E continued from page 15 ANALOG SWITCH LOSS rm building a circuit that uses a 4066 CMOS analog switch to select between various audio sources. Everything works fine but I notice that there's some loss in signal level through the switch. According to the data books, a closed 4066 switch acts tike a 75-ohm resistor and, since that is a characteristic of the IC, rd guess there's no way around it. Or is there? — W, Mer- edith, Elkins, WV Analog svsrilches are neat devices that allow digital circuits to control the flow of analog signals. When these IC s first appeared on the mar- ket they were immediate hits. But youVe right, there is an internal loss. While there's no way to pop the cover off the fC and do a bit of cre- ative microsurgery to cut down the signal loss, there are some more conventional alternatives that can help. After alL the losses are due to routing signals through transistors as opposed to mechanical con- tacts. The most obvious answer is to put a simple amplifier after the switch* which is what I would do if faced with your problem. A one- transistor or op-amp circuit doesn*t cost much nor does it take a lot of board space. An added benefit is that you'll be able to adjust the over- all gain to any level you wanL And since you're dealing with audio, it's not much of a job to tailor the amp's characteristics to match whatever equipment the circuit has to feed. If you're not using all the switches in the IC. there s no reason why you can't use two or more switches in paralleL The apparent resistance will drop in the standard jieciprocaf- addition pattern used for calculating the equivalent resistance of parallel resistors. You can never reduce the resistance to zero but you might be able to get it down low enough to make the problem unimportant. Your last alternative is to use a different IC. Some of the more ex- pensive analog swritches designed for video and other high-frequency applications have a lower inherBnl OmCLE lit ON FR£E FORMATION CARD R'E Engineering Admart MIDI PROJECTS BP182— MTDf interfdcing enables any so equipped instalments, fegardless of me man- ufactyrer. \q be easily connected together and used as a system with easy computer control o1 these music systems. Combine a computer and some MIDI instruments and you can have what is virtually a pfog rammable orcheslra. To order your copy send plus S2.5D for shipping in the U.S. to Electronic Technolugy Tnday Inc. , P.O, Box 240. Massapequa Park, NY It7e2-[I240. Rates: Ads are IV^'xiW. One insertion each. Six insertions S950 each. Twelve insertions S9Z5 each. Closing date same as regular f?te card. Send order wilti remittance to Engineering Admart, Radio-Eleclrcnics Magazine, 500*B Bi-County Btvd.. Farmingdale, NY 11735. Direct teleplione inquiries to Arline Rshman, area code-1'5l6-293-30fl0. 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WPT PUBLICATIONS 7015N.E. 61sl Ave. Vancouver WA 98661 Phone (206) 750-9933 Dept. 50 ClfK:LE m ON fBBB INFORUATION CAfID aRQLE tea on free information carp WU'REIHROWING n ALL AWAY. 1-800-CALL-EDF signal loss but they're much harder to gel in single quantities. A less expensive and more available choice would be something like the 4016. the father of the 4066. That earlier chip has a higher internal re- sistance (about 300 ohms), but does a better job of preventing sig- nal leakage. Anyone who stocks the 4066 would probably stock the 4016 as wefL FM ANTENNA Tm having a lot of trouble get- ting good FM reception in my home. No matter what kind of antenna I try or where I put it in the room, the reception is garbled and distorted* I live only a few mtles from the main trans- mitting antenna so I know it's not a problem with the level of the signal. Tm thinking of get- ting one of those devices Tve seen advertised that turn my electrical wiring into an anten- na. Do they really work? — L, Lasky, New York, NY 1 thought those phony baloney contraptions disappeared along with more important things like the Rosicnjcians CAMORC everyone) and White Cloverine Brand Salve, The answer is a definite no. Few things in life are for sure but the fact that those antennas are a waste of time is something you can bet on. The reason you're gettmg such terrible reception is because of mul- tipath reception. The signal fnDm the transmitter bounces around off the metal in buildings and you're getting several delayed versions of the same signal. If you had the same problem with TV reception you'd be talking about ghosting. And the way to solve the problem is to follow the same n3ute you would with ghost- ing: increase the signal strength. I've seen lots of devices that pur- port to eliminate multipalh FM re- ception but I've never run across one that delivered what was prom- ised in the ads. The bottom line is that if you have excessive signal re- flection and the reflections are strong enough, you're going to have poor reception. FM antenna ampli- fiers — the ones that go in front of the antenna inputs — can solve problems caused by a weak signal but they can't do anything with nnu)^ tipath reception. As they say, gar- bage in. garbage out. Until someone out there can show me otherwise, all you can do is try to get cable FM service, or put your antenna somewhere that it has a clear shot at the transmitter's an- tenna. That would be out a nearby window if you're up high enough, or out on the roof if you're not. R-E i P 3] a. o' m 79 3 PROnSSIONAL BOOKS JnlV ^9 Take any when you join the ELECTRONICS ENGINEERS' BOOK CLUB 5258 $28.95 Thii book ofTm up-to-date imtruciioflts tor troubleshooiing and repuruig ftll major br^.v i>r equipment wjih huncfreds of djagiams, ii.pccs, and ixihcmatk'Jt, Covers TVs, VClLs. 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If you prefer another selection, or no !te lection at alt. stmpty indiotic your chtiicc on tbe reply f-4 wcclm, «aJ f wiJl hmv M kau tO to m^ieaim. U I wa£i die }.\^ &^x£iDn. I axd tbi t»«}ur^. e miHtttiifptdmma^xai- \y. If f Witt ■ diflercn book at bouk ii alt 1 t>i]t aatity ihe Cluh by rcursiaf tfie eifii |inrrid- cd- 1 airee if» purchaw ju^ 3 imwe Kkctiora. ii rcgukr club pneoi wiiMs the m%t 2 ytirt anJ may mipi inyiimc [fKiiuhcr □ Plevc dskrse my □ VISA O MastvrCimt Q Afnerkwi Expccii § g. 9 m Addnu . Ciiy must 3cc..n.pan Offer nvlvl Lqr acv gg s^ ff- 1^} , wJlfeei H M AppLk-uA aduJe be L'.S uid Cjula vdl jas 83 COMPUTER CONNECTIONS Windows 3.1, OS/2 2.0 JEFF HOLTZMAN S? P g t3 84 Windows 3,1 is destined to be an extremely popular upgrade to MicnDsoft s ai- ready popular graphical operating environment. It is an incfementaJ up- grade that fixes many small prob- lems and adds several significant new features. 1 wish Microsoft had gone further with some things, but there is enough new and improved here to capture a heck of a lot of user interest (and dollars). This re- port is based on the "final" beta C3.1.061d. shown in Fig. t); some features might vary slightly in the finished product (due out by the time you read this). Win31 contains five major areas of improvement: higher reliability. Object Linking and Embedding COLE), the TrueType font system, a new File Manager with "drag-n- drop" file managGment, and lots of small user- interface enhancements. Let s discuss each in turn. Improved reliability is first on the minds of many (including yours truly). Put simply. Win31 is not as robust 33 OS/2, but it s better than Win30. When a program crashes, it usuaIFy brings up a dialog box stat- ing whens the fault occorred. and allows you to terminate the applica- tion without rebooting or corrupting Windows internal memory-man- agement scheme. I say usualfy be- cause (at least in the beta), it s still not 100% reliable. A related feature is Ctrl Att-De- lete trapping: You can't simply re- boot at any time. If you press Ctrl- Alt-Delete, a text-mode screen pops up advising you to press the key combination again if you really want to reboot, to press Escifyou*d realty rather not reboot, or press En- ter to terminate the current applica- tion. The purpose of the latter is to terminate hung applications. If an application hangs, you can "reset" just that session and return to Win- dows, CDESQview has had that fea- ture for years; it s about time Windows got it as weW) CbecMMjd SNfftt/a M^jetnate H^t^^ lAktt^ Biixz 1 M j 1 S 1 3: view Dpbon? Help PriffI Maniyer RG. 1— WINDOWS 3J contains improved reltabfltty, object finkmg and enfibeddlng, and lots of small improvements that together add itp to another run-away success for Microsoft. OLE Object Linking and Embedding COLE) provides the most interesting and far-ranging enhancements to Windows. Recent versions of vari- ous Windows applications CExceL WinWord. Ami, PowerPoint) have been getting smarter and smarter about how they integrate data from other applications. For example, you might want to include an Excel worksheet in a budget statement, or include an Excel graph of data coliected as part of a school report. In the ofd way of doing things, you would leave a big hole in your docu- ment* print the worksheet or graph separately then paste the printout physicaify into the document. Savvy Windows users have* for several years, eliminated the physical cut and paste, instead doing so thn^ugh the Windows clipboard. However, doing so has limitations. What if the Excel data changes? Then you must delete the version in the docunnent and **paste*' in a new one. A better way is to set up a "link" between the Excel data and the word-processor document. The Imk allows you to work on both docu- ment and data separately, perhaps with separate users performing dif- ferent tasks. The word processor watches over the link; when it de- tects new or changed data, it up- dates the document with a new copy of the spreadsheet. An embedded object is quite dif- ferent* and there is much confusion floating anDund about this point. An embedded object exists onfy in the main document, not in a separate file. That means that only one user can gel at an embedded object at a time. Let's back up a couple of steps. What does Microsoft mean by the term object? In the Windows scheme of things, an object is a chunk of data. It could be a cell in a sprEadsheel. a range in a spreadsheet, or the entire spreadsheet. It could be a para- graph of text or a whole docunaent. It could be a bit-mapped image ere* ated rn a paint program. It could be a sound file containing voice annota- tions to a document. The point is that it could be just about anything: the "document'' containing such an object does not need to know how to display it or print it. Object linking and embedding doesn't happen in a vacuum; ap- plications must be '"OLE-aware/' There are two types of OLE-aware applications: OLE servers, which provide objects that can be linked to or embedded in other docunnents. and OLE clients, which can accept objects supplied by an OLE server. A given application can be a client, a server, or both. In Win31. Paint- Brush and the Sound Recorder (only available with multimedia hard- wane) are OLE servers: CardFile and Write are OLE clients. Current ver- sions of Excel and Word for Win- dows can function in both roles. (The next version of Word is rumored to have extensive built-in OLE capabilities J Whereas a linked object exists in a separate file, an embedded object exists only in the primary file. You edit an embedded object by double- clicking on it. which causes the cor- responding application to load with that data. After you edit the data, you close the second application, which inserts an updated copy of the object in the document. What about applications (DOS pnDgrams. for example) that are not (and may never be) OLE-aware? Wjn31 includes a special prx^gram called the Object Packager What it does is link an application and its data file to an icon that you embed in an OLE client. The type of applica- tion and data is irrelevant: all that appears m the OLE document is the icon. To access the "packaged" data^ you double-click the icon. Win- dows then executes the corre- sponding application. The iconic representation has some interesting ramifications. Hard-copy and on-line versions of OLE documents differ The hard- copy version will contain only the iconic representation, not the actual data. The irony is that the on-line version will be richer than the hard- cof^ version, not the other way around- The implication is that you'll need a computer to get at all the information contained in the OLE document. As computer hardware continues its evolution toward rich, standardized multimedia ca- pabilities, this will become the rule rather than the exception. The whole OLE procedure is awk- ward, time-consuming, and distract- ing. In the current way of doing things, a whole new application launches in a separate window that takes you out of the context of your document. Ideally, when you se- lected an embedded object, the menus and tool palettes of the cur- rent application would change to re- flect available capabilities. Then you would have the feeling that it was your document that mattered, not the computer applications used to create it. OLE represents the first cut at that type of transparent edit- ing capability, TrueType Microsoft s answer to Adobe Type Manager (as well as similar products from BitStream and others) is called TrueType. TT pro- vides built-in device-independent scalable fonts. Device* independent means that, within the resolution of the device, fonts will appear identi- cal on any supported video display or printer With font support built into the operating system, docu- ments can easily be ported among different machines without loss of fonmatting information. Win31 includes four typefaces corresponding to Helvetica, Times. Couner, and Synitx>l These fonts are rendered quickly and are quite good looking; Adobe might be in for trouble on that count. Professional desktop publishers will likely still prefer ATM and Adobe Type 1 FbstScript fonts, but run-of-the-mill users probably won't care whats under the hood as long as it works. And even in this beta, it does. IVe already seen lots of public-domain TT typefaces floating around on the telecommunications services. WtnSIs ability to work with both TrueType and PostScript Type 1 fonts was unclear as of this writing. Get a reading of in three seconds for as hwas$MM pt^tBtmbk powef supply wiith buiH in (SPIBr No more wasting time twisting, turning, or hveaking knobs. Get- ting quick, accurate readings is pushbutton easy with any of American Reliance's progrom- mabte power supplies (PPS), Today's technotogy makes PPS ovoiobte at he same cast of a standard linear power suppfy. Why not move up lo ttre eose of use, occuracy ond convenience do PPS? As Q special offer, wtth the purchase of any PPS, you may also pufchose the fulhfeatuie 4000 count Auto-Range DMM (3010) for $SBM wtth a two year warranty! Thof's a legular $149.00 value. Each unrt comes with a free tiial offer. If after 15 day$, you ore not satisfed with the performance of our PPS, simply return it - no questions osked. fw a full refund. However, you hove the option to purchase the DMM for just $79.00. EITHER WAY YOU WIH! MODEL ! SPECIi^lCAlJOhiS USERPRCE 1322 SINGLE 32V/2A $396.00 1302A SINGLE 30V/2.5A S595.00 1326 32V/3A OR 16V/6A S895.00 107 10 SINGLE TV/lOA 3895.00 2322 DUAL32V/2A ! S996.00 1603 SINGLE 60V/3A $1J95.00 FOR DETAILS, CALLi 800S54''9B3B AMERICAN RELIANCE INC TIL (liaj 575-51 10 FAX: (818) 57S-O801 aRCLE 17a ON FREE INFORMATION CARD It s important to understand that TrueType is no substitute for PostScript. PostScript is a robust language for describing both fonts and complex page layouts: True- Type covers only the font portion. Microsoft has a related technology. Tryelmage, that attempts to make up for the deftciency. However, few laser-printer manufacturers and even fewer application programs support either Tmelmage or True- Type. The point is that PostScript is well-supported, hence is likely to be with us for a long time. Other improvements File manager is incrementally faster and easier to use- Using the fvlultiple Document Interface (MDI), It allows you to open multiple win- dows into various drives, and then to copy and move files among them. Drag-n-drop allows you to select a file from the file manager then drag it to another application to move, copyn or print the file. Moving and coining work fairly wel!; the print feature Is not so elegant. For exann- ple. if you drag FILE.TXT to the Print Manager, it tn turn launches NOTE- PAD.EXE. which does the actual printing. You can drop the file fcon on either the minimized PrintMan icon, or on the open PrintMan win- dow. The idea behind this capability is great, but the implementation is awkward. If I drag something to the printer icon, I just want it to start printing while I go on about my busi- ness. Instead, the dnopped-on ap- plication takes over the screen and keyboard until printing is done. For this capabifity to work smoothly ap- plications vendors are going to have to cooperate, i.e., provide DDE-ac- cessible print modules that do their thing in the background, without dis- turbing the user FileMan also pro- vides a **backdoor'^ capability for adding new functions: already there are shareware packages that do so, FileMan is much better than in pre- vious incarnations, but I would have a hard time giving up the Norton Desktop for Windows. As with Microsoft's recent re- lease of Word for Windows 2.0, there are lots of small userinterface improvements that together add up to a much more pleasant computing experience. To name a few. Prog- Man and FileMan save settings much quicker when exiting; high- speed support for many super- VGA cards is built-in; full mouse support for DOS apps running in a window; faster switching among applica- tions; a large colfection of applica- tion icons: built-in screen savers: built-in multimedia support; built-in tutorial on Windows operations: a Startup group in ProgMan (the visu- al equivalent of the LOAD- and RUN= lines in WIN.INI): better support for COM3 and COM4 se- rial I/O; variable size fonts for win- dowed DOS sessions. In prior versions of Windows, you could press Alt-Tab to cycle through all open applications. Win31 in- cludes a "smart" version in which you press and hold Aft: subsequent presses of Tab cycle through a win- PLUGViniTO THE WEATHER! The ^3-10 Windstaiion roof- top ^ven^or plugs dirfctly iim the PC Game Pnru It sends you immetliaie mta5i]remefitsof your local weal her pat lerns. Wind speed, direction and gust vaJue data are continuous I v displayed. 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When you neach the one you want, release Tab and you switch to it. Simple but elegant. VVin31 includes an updated ver- sion of Micmsoffs disk caching pro- gram SmartDrv. SmartDrv 4.0 hooks in at the DOS level, hence is able to cache more types of de- vices. The program now includes the ability to cache both reads and writes. In addition, the final version should have its own Ctri-Alt'Delete trap which will help ensure that cached writes actually are written to disk before the system resets. In conclusion. Win31 sports many small improvements and several in* dicators of great things to come, Windows is still not perfect, but it's a whole lot belter. The detailed atten- tion paid to improved user interac- tion echoes similar improvements in the recent release of Word for Win- dows 2,0. This type of user focus is what would-be competitors had better pay attention to. OS/2 2.0 update Flash: I just neceived beta version 6.304, which now allows Windows and OS/2 windows on the screen simultaneously. My initial impres- sion is highly favorBble. Choosing between OS/2 and Windows is no longer as easy as it once was. More next lime. Multimedia update As soon as things settle down on the system software front, I will get back to my promise to provide an in- depth look at CompuAdd s multi- media upgrade kit. which puts a CD-ROM. sound card, and optional AM/FM and TV tuners in your PC. You ve gotta see it to believe it! R-E "i>f guess: The rompuier never f^aes de ifi Spare time, prt^l^oy 5 u perienca naeded! No costly schooL No commuting to class. The Original Home- Study course prepaid you for the "FCC Comtnercial Ratlio- telephone Li cense" This valuable I ice use is your professional "ticket" to thousands of cxcilipg jobs in Communications. Radio- TV. Microwave. Maritime. Radar. Avionics and more... even Start your own business! 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We specialize in a wide variety ot technical informatroa parts and semces for CB radios. 10-Meter and FM conversion kits, repair books, plans, high-performance accessories, Thousands of salisffed customers si r^ce 1576' Caialog S2. CBC INTERNATIONAL RO. BOX 31500RE, PHOENJX, AZ 85046 60C52'Sasfc mECftKontroller board. Basic inter- pretor, 32KRAM, 16K Eprom^ Eprom programmer, RS232h expansion connector Bare board with manual, schematics S0C52-Basjc micro- processor chip $25.95. Assembled and lesled $124,95. PROLOGIC DESIGNS, PO Box 19026, Baltimore, MD 21204. JHRFIOLD, Tocqm and Zenith "test" chips. Fully activates unit. SSO.OQ. Cable de^ scramblers from $40.00. Orders 1 (BOD) 452-7090. informatron (310) 667-OOat. CLOCK, 1-32MH^ variable square wave gener- ator. Request specs, price. TRDLEX, 1292 Mearns Rd.. Wfeinrtinsier. PA 18974. Quafitv Microwavo TV Antennas WIRELESS CABLE - IF7S - MMDS ATiatCUl TV UI1T3 Hii^h tiin £DdE)f^) » Tirnv^:!]:]!: T 9 to 2.7 GFrl. • 55 -Cha nnG I D; sh SysJ-^m S 1 ^9.95 • 36-Chann&l D^sh SySlem S 1 4 9.95 • JO-Channel Oish Sysiem Si 24.95 » Vj,:;; ,', rr 'i;i! •■■.Ti : ! !' i ■:':-.:''i iLiing Availafilf PHILLIPS'TECH ElECinOHECS Oisn Sf%\€m P.O. Box P1533 . Sc[>tt5id.ilft, AZ 852S2 UFCTIUE i^eZI 947-77 DO 1 00 Cet^iEit All phcne OrilCf FIBER optics kits, E^tperlmenlers £24.50 Dalalink w/PCB $36.25, HILL ELECTRONICS, Box 47103. Phoenix, AZ 05068-7103. TOCOM-Jeirotd Impulse-Scientific Attanta Converters, two year warranties, also test mod* utes for your converters. Contact NATIONAL C A- BLE, (219) 935'412B full detaijs. HIGH voltage rectJtiers! 6KV-$4.50; 10KV-$11,00; 14KV-S13,00: t6KV'Sl6.00. AIJ 1 amp. $3.00 shipping per order. SMI, Box 5SG0-A, Ukeland, FL 33807, (813) 646-7925, FREE catalog. Great software $1.50 per disk. Write: FESTUS MASAI, PC Box 1036, DeKalb. IL 60T15 ^^^^ SEMCORE test equipment, parts and manuals. DON JACKSON, 255 Wofth Rainey Lane. Cave City. AR 72521. (501) 283-6236. ANTIQUE RADIO CLASSIFIED Free Sample! /^^^^^%] A n liq u e R adio's \^^^ kiMOi \& Largest Circulation Monthly. [iPy^ j Articles, Ads & Classifieds. 6-MQnth Trial: $15. 1-Yr: $27 ($40-1st Class). A.R.C., P.O. Box B02-L9. Carlisle, MA 01741 FREE cahfe descrambCers. 2 free M-35B when you buy 8 at $29.00 ea, 1 free Tocom when you buy 4 (rt^ $105.00 ea, 1 free RTC- 56 when you buy 4 (« S99.00 ea, 1 free SA3-6or FTB when you buy 9 {&■ $59.00 ea. Others in stock. C.O.D, OK. MOUNT HOOD, (206) 260-0107. DESC RAMBLERS Oak. Jerrold, Zenith, Tocom, Hamlin. Lowest prices, best warranty C.O.D. OK. Same day shipping, quantity discounts S.A.C*, 1 (800) 622-3799 M-F 7-3 RS T. T^ST-AJds for testing units In fuH service mode, Sfarcom Vit. $40 00; Starcom VI, S30 00; Star- com DPBB, S50.00; Pioneer, $75.00; Tocom VtP 5503.5507, $25.00: SA. call; Zenith, $25,00; N.E. ENGINEERING, (617) 770-3830. BUVING cable boxes, any quantity. Also selling test lum ons. Call 6-11 PM EST (305) 425-4378. BATTERIES. Huge savings on Ni-cad. alkaline and hard to find batleries. Custom made battery packs to your specifications. Camcorder B/C electric model, cordless phone and other bat- teries, Caialog $2,00. B&J, PO Box 1833. Snohomish, WA 9B29V1833. CABLE TV descramblers converters. Whole- sale price club. Nobody beats our pricesi All majOf brands. Money-back guarantee. COD cred- it card orders — CABLE ONE 1 {800} 669-530^. Sorry no California sales CABLE equipment... whofesafe only. Starcom 7 tost kits $1B.£WJ. New tags from $25.00, New converters from 348,00, Stun guns (rem $20,00. Starcom 6 factory Tri-bi combos from $99*00 ... in quantity to the trade 1 (800) 866-2232. PLANS AND KITS FASCINATING electronic devices! Dajerst Lasers! Transmilters! Detectors! Free energy! Teslal Kits assembled! Catalog S4.00 (re fund a- ble) QUANTUM RESEARCH, 17919-77 Ave,, Edmonton. AS. T5T 2S1 HOBBY/broadcasting/HAM/CB/surveillance transmitters, amplifiers, cabie TV, sdence, bugs, other great projects! Catalog Si .00, PANAXtS, Box 130-F6, Paradise, CA 95967. REMOTE CONTROL KEYCHAIN Compkic w.'mJnI-trsnsmitle* FuUy assembled inclU'ding p[nn* :. 10 build your own out 0 fl'amni Ouanljty discounts svailablflf; ^ryjt Ghaclt.Vlsa or M.h;; piClH.bfD Add $ 3 shipping^ VISITECT INC. Sax lilSfl. fremont Ca. 945^ (510)651-1425 Fax (510) 651-8454 PCB and schematic CAD, S195.00 IBM EGACGA Multilayer, rubberband, autovia, NC drill, laser, dot matrix, pEotler, library, Gerber. AUTOSCENE, 10565 Bluebird St„ Minneapolis. MN 55433. (612) 757-6564 free defTto disk. DESC RAMBLER Kits, Complete cable kitS44 95 Complete saielfFte kit S49.95. Add S5.00 shippfng. Free brochure. No New York sales, SUMMIT f^E* Box 469, Bronx, NY 104 65, SURVEILLANCE transmitter kits lune from 65 to 305 MHz. Mains powered tJuplex, telephone, room, combination tele phone -room . Catalog with Popular Communjcatlons, Popular Elec- tronics ar^d Radto- Electron ICS book reviews of **Electronic Eavesdropping EquJpmei>t De- sign/' $2.00. SHEFFIELD ELECTRONICS, PO Box 377785 -C. Chicago. IL 60637-7785 DESCRAMSLtNG. New secret manual. Build your own do scramblers for cable and subscrip- tion TV Instructions, schematics forSSAVI, gated sync, Sinewave, (HBO, Cinemax. Showtime, UHF. Adult) $12.95. $2.00 postage, CABLE- TRON ICS. Box 305O2R. Bethesda, MD 20824 LEAD ppijr\\#p&uiid kit Htiich rvTnom lead ■ » 1^ vDcaJs bDfn standard stefeo records, €D'%, tapes or fU bro*tfeai$s S^g along with Ih* teclqgreund ffli^ic A I i> ^ ""V component VUOALS Adcfitbnal lit iw*fb to _ „ ypyr vcie*. th*n niim it vitti fnuiic cai] or write Pro-ttiMrfiibtod boanft wiftble. for free In fo Weedef Ttchnolc^jies, 14773 Und- CS13] 444-22/a seyFW i l,*t. OrBb. Ohia 4515*. ETCH PCB's yourself, no chemicals, easy, choaa full instructions, S2,00. SASE, NICKMAP, PO Box 593, Howell NJ 07731-0593, DEFEAT videotape anti-copy. PCB PAL inslruc- tions $16,50 w/PH. NORM HOGAflTH. 955 NW Qgden, Bend, OR 9770L HAMD held digital recorder announeer. New technotogy porrtiits permanent slorago o1 persor^- al reoof dings and messages, Plans S9. 9 5 Kit S49.95. Send check or morwy ordcT to CD&M, 303 Nortrrwoods Drive, Baliground. OA 30107. TELEPHONE Profectsr Automatic recorder inter- face-S7.00, disable extension plnwi«s*S7.00. phorie ltf\e bcsng used ind}cat0f-S74M], Meet ex- terYsion phonos'S7.00. FM telephone Iransm li- ter- S7 00 Detailed pSans mdude film positive (or makirkQ yout own prmted orcuit board! Free cata- log! TEGHNOTES, Box 2308. SeaJ Beacfv, CA 90740-1308, BUILD your own stereo! Complete plans and schematics lor amplilters. passive active crossovers. Z-butfers. LED meters, speakers, and more. Send SH.9S to BT ELECTRONICS. 424 7th Ave. S,, Brookings, SO 57006. (605) 692-7B57. CREDIT card encoding standard explairred in plain English. Illustrative examples included, send esc, Box 1S41. AJexandna. VA 22314. VHF-fM amplifier plans 7SllOMKz. 1 5-25 watts. S8.95: PROGRESSIVE CONCEPTS, t313 Mon*i Grand Ave.. #291, Walnut. CA 91789. CAM PALE RT backpackable perimeter alarm kit S3995 ^$3 00 Send stamp info PROTECTION CONCEPTS* 340 Toriance Ave., Vestal. NY 13850. FREE CATALOG! 1-800-648-7938 JERROLD HAMLtN OAK ETC CABLE TV ■ ■]=^iH:yiVM:il=l:kl • Sf>6cia{ Deatef Pricss.' • Compare our Low Rmi! RricBs! • Guarameed Prices & Warmntms! • OrtfefS Shipped fmmeaiat&ty^ REPUBLIC CABLE PHODUCT^, INC g 40S0 Paradise Rd, #15. Dept RE£t2 PT/I 3 Las Vegas. NV 69109 For afl other information (702) 362-9026 BUGGED? Telephone tapfjed? Find out fast! Free catalog ol fantastic counter-surveillancQ equip- ment^ STUDIO quafiiy FM broadcast transinrtter. Dig- itally synthesized, crystal conlro^fed unit. Uses three sialo d the an chips, Can be sol up to 400m W. Transmitter kit Si 50 .00. 4 wall booster Kit $60.00. Sten^O processor kit St 50 00. Send che- que or money order to WAVEMACH COMHUNh CATIONS, 0)0-2261 LaKoshoro Blvd. Wesl^ Etobicoke, Oniario. MeV-3Xl. UNIQUE kits* Send for free caiaiog LNS TECH^ NOLOGIES, 20993 Foothill Blvd . Soiie 307R. Hayvward, CA 94541-1511. SATELLITE TV SATELLITE TV — Do it yoursetl systems, up- grades, parts Major bfar^ds discounted 40^«-e0%. we il beat evefyone^ price. UIH INC^ can Larry (609) 596-0656. DESCRAMBLERS [ MAKE THE CONNECnOH NU-TEK ELBCmONI CABLE TV EQUIPMENT SI ORIIKR TOIJ. 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Poflad ptBta span with inlovaf cr«sovsfr Fradutt^cy re^poTLSti aO-fiOO Hz. 5Q watts RMS, c^fi b& mounlfid almcs] anywhere, Froquency naponse: SK-20KH/ 97ifi iw/lM Pow^ tisndboa. SO wans RMS. «hn used with a O rrucrtitarecl cap.icitor SoM in pairs Nel weightr 1/2 lb #RH-265-267 $24" $22^ 12 Ga. Speaker Wire Extra largo ^auge spcakfif wif& lor ■m\h very high powdr storM systoms arwJ for \ae m eKtretT«Jy tariq c^tilanjns Otfer2&y strands d 36 ga, wtre fjlfa thick, dear PVC jroulation Pteaw onttt in multlfilleii olSfnt surround 2* dual voiciicoit ti-= 45 Fraquency respon,'^.: 45^KHi Seosrtiwty 96.69 iW/tM. VAS^ 3.73 OJ h . QTSs .33a &6CtSW32l/FB m wcighr: 9 lbs. #RH-294-130 SI 39^ S128^ (4-up) 8 Ga. In-Une Fuse Holder SchTvsrEiivilY: M wans m-iitmum powaf handkiQ eapabiltty. 7 dB t W/1 M._ Dimonsions; Note dtf^iensKJTB 9*"{W) X ia^L). #RH-30CM3Q Suq List Parts sss^ $79«i nAde, Tte phones. Sxlion cup gnp mounls on. mside olcar. Never have your cni vandaiiied again Anlonru comes wdli 9 l«t of HG-Se with TNC connector. 3 dS sm the U S A {i'9t fRMTO^ High Voltage Cap Kit This dS prtCd i*4 contains a selecboA pi 2SC. 330, arrurciiasod ir>dividuallv- Mijighl: 1 lb #RH-020-9S0 $14 Each 340 E. First SL, Dayton, Ohio 45402 Local: 1-513-222-0173 FAX: 513-222-4644 •S30 00 rrwiimtjm oriler ' We accept MasftHcard, Visa, Discover, nnd C. O, D, orders- • 24 hoyf ehippuig • ShipflingdWOa': UPS chart role %\ 00 (S3 50 minimum chai^* J ' ■ Hcxjfs S30am - 7 <» pm EST Jiptonday ' Foda r ^ 00 am ■ 5 00 pm GahjrUay. M«i onior o^lomcKS. pioase coi tof shipping osi^naio on orders enceed n q S las. ' Fofei^ destnalion Gfiianwfi please seaidSSOOUS hnlt tor catalog postage - ' FREE CATALOG CALL TOLL FREE 1-800-338-0531 i 31 Q. rri 3 ^ 91 CIRCLE QH FR££ INFORUATtQN CARD AMAZING ^ ELECTRONIC ^ PRODUCTS and KITS fieinember those Martan Space Ships \n HG Wetis WaroftheWortds? MYSTERY Levitating Device Objects float on air and move lo \hB touch, De(tes gravity r Amaiing gift, conversatton piece, magic Irkk of gru^l scientific project. AHT1K EasyAsB'y KtlPlan s|\9.50 3lyltL£ FM Wireless Microphone! Crystal clear, ultra- sensitiva pickup transmits voices. sourKlS 10 any FW radio. For security, monitoring children, invalids. Be the local DJ! MVP1 PlMns $7,W MVP1K Kit/Plans.... . , . . . $ 39.50 3 MILE Telephone Transmitter! AutomathcalFy transmits 2 sides ol phorte convafisation to any FM radto. Tunabte, easy-assembly PC board Operates only when phone is in use. VWPM7 Plans $7.00 VWPMK7 KitiRans W9.S0 TV & FM Joker/Jammer Pocket size device tots you remotely dfErupl TV or radio reoeptfon. Great gag I Discretion required. Easy-build electronic kil. EJK1KM_. . . . $19.50 100,000 V - 20' Range Intimidation Device! Electronic module, may be snctosed for handheld, portable, or fixed uses. rrM2 Pfan9 {cred^tab^o to kit] 510.00 fTM2K Kit & Plan s $4950 READY-TO-USE, AUTOMATIC Phone Recording ^0 Cornpfete with extended play tape recorde/ £ l\m interface swtch. Autom.ai3cally records both sides of conversation Check Locai Laws on Proper Usel Ready to Use System. TAP20X System $149.50 INFORMATION UNLIMITED DeptRE-4 Box 716, Amherst NH 03031 Phone 603-6734730 FAX 603-672-5406 MC, VISA, coo, Check Accepted. ADO $5 S&H. X^Ofder hy Msjf, or by 24 Hr Order Phone: 900-221-1705 Laser Pen Pen si;ed laser, great lor movi&s, drive- ins, pointer. Ready to yse. wilJi ba ns. LA PH1 Laisef Pen . $149,50 Pocket Laser Kit 3mw or Sfnw kits, with sotid state 670nm d^ode. Caution, Class tlia item. VRUKM 3mw Laser Ktl . . . $99.50 VRL5KH 5mw User Kit.. $119.50 MOflE Laser Kits! LAS1KM Imw Laser. 632nrTt, HeNe Easy to Build Kit ... $69.50 LAS4KM 3mw Version . Kit S99.50 LATOS Low Cost KeNe Laser Tube! ,5mw Tube & Plans . . only $24.50 OiJier parts available separateiy, Great Low Bud g et Scie nce Pr oject! Shocker Force Field ^Vehicle Electrifier Make hand shock balk, shock wands electrify objects, charge capacitors. GreaJ pay back br those wise guysf 5HK1KM Easy-Assembly Kit $24.50 CATALOG! with many more items! FREE with order, or send $t PiH FREE catalog — Lowest prices wortdwicfe. Satis- faction guarantee on everything sold — systems, upgrades, pads, all major brands factory tresh and warrantied. SKYVtSION* 1012 Frontier, Fer- gus Falls, m 56537. 1 (80O) 334-6455. Outside DS (218)739-5231, SATE LUTE -Cable descrambling secrets-sur- veillance transmitters: Send S2.00 lor catalog. COMMUhtiCATtONS EMGINEEBING, 76 Boule- vard. Hudson Falls. NY 12839. CAHl.H T\ l)i-:.S( KAMItl.KKS BEST BUYS BEST SERVICE aULLET PROOF TV TESTED WANT TO BUY; TOCOU, SA &A9D.DPV7Z12 I^ubL be niBionibts prlcoi CaLal v S^nd (1 CO TO; BBctronka™ mCi S0.12lnl DiiUri Wanted 1 800-835-2330 92 CABLE TV OESCriAMBLERS THE IVSDBT ADVAISJCED TECHNOLOGY IN CABLE EQUIPMENT • BA^ aAPCl • JERRDLD •PIONEER • TDt:aM • HAIWLIN • ZENITH • SOENTtFlC ATLANTA • OAK FOR DLTT OF THIS WORLD PRiCIES CALL WORLDWIDE CABLE 1 800-77S-3S33 FREE CATALOG AVAILABLE 1291 A POWERLIh£ ROAD, aJFTE 109 PDMPANO BEACH, FL 33069 fs/C / COO/ VEA Nq Bnnda Sales SECRET cable desc ram bier. Build your own de- scrambler for tess than Si 1.00, in seven easy steps. Radio Shack parts list included. Also free descrambling mettiods that cost nothtng to try! Send SI 0.00 to LOUIE WHITE, 2 Mad in, BaytOWn. TX 77520. VtOEOCIPHER lit descramblinjg manual. Sche- matics, video, and audio. Explains DES^ Eprom, Clone Master, 3Musketeer^ Pay-per-view (HBO. Cinemax. Showtime, Adult, etc) 316,9S, S2.00 postage. Schematics for Videocypher Plus. S20.00. Schematrcs tof Videocypher032p $15.00. Collection of software to copy arid alter Eprom codes, $25.00. CABLETRONICS, Box 30S02R. Bethesda, MO 20824. BUSINESS OPPORTUNITIES YOUR own radio station! Licensed 'unlicensed AM. FM, TV, cable. Information $1 00. BROAD- CASTING, Box 1 30- FG. Paradise, OA 95967. LET the government finance your smafi business. Grants/loans to $500,000. Free recorded mos- sage: jiQi) 449-8600, (KSI). MONEYMAKERS I Easyl One man CRT rebuild- ing machinery S6,900 GO rebuilt, $15,900.00 new. CRT, 1EJQ9 Louise. Crystafake. IL 60014. (815) 459-0666. Fax (815) 477^7013, PAY TV AND SATEILITE DESCRAMBLING AIL NEW IMZEOtTtON ALL NEW 1993 fdiiiori upd^tt Oft atlifl. *iKtes5 ana sileRite run-ons. ciftuits. iMjIleJi, bags. B- Mjc, b'ackipTwis t^iMies New VCPkjs f ijiss. Oui (HJSt yet !991 Efliiron. £15 % each MDS HanijbcicrSt KJ » SjttHiie Systtms uiv^cr S600 SI? 95 A-iv 3*?3 9f) or b'ti'^ 35. Scsifntiliiig Nms Vejr One (154 Qaq«)5.'-iV: -. ■■ y.^'-'- '■^---■■■■j V-*-.V--:^!Yt249S.'yf S^mpk Kcramblini;} Hews, 1552 Hartel Ave., BultalD, NY. 14216. Vcfice.'FaMTie) B74-208a EASY work! Excellent pa^E AssembEe products at homo. Call toll free 1 (300) 467-5566 Ext. 5192. MAKE SSS! Become an American electronics dealer! Profit opportunities since 1965. Call SCOTT PRUETT. 1 (BOO) 872-1373. HOME assembly work avallabiet Guaranteed easy money! Free details! HOMEWORK-fl, Box 520, Danville, NH 03619. MAKE $75,000.00 to $250,000.00 yearly or more fixing IBM color monitors. 1^0 investment, start doing it from your homo (a telephone required), fntormation. USA. Canada $2.00 cash for bro- chure, other countnes Si 0.00 US funds. RAN- DALL DISPLAY, Box 2168-R, Van NuyS. CA 91404 USA. Fax (816) 9&0 7803. SATELLITE TV NAME mmm at 50% discount This FHEE 24 page Consumer ^v^'m Gulcfe im all about Satellite TV and lists guaranl€Q{| I owe it prices, 1-8D0-472-8626 . IKTERESTED in import electronic surplus, bar- gains from USA. Write M'ELECTRO^ilCA, 23660 Alcaudete Jaen Spain. Fax 34-53-561143. DESKTOP payphQne(s) — send $2.00 for liter- ature. TEL EVE NO, PO Box 77. Fall River, MA 02724. (508) 675-5474. MAKE money, in your own import-eitport busi- ness! Report S3.00. SMO, Box 7592, Elgin, IL 60121. EDUCATION & INSTRUCTION F.C.C. Commercial General Radiotelephone Ik cense. EJectronics home study. Fast, inexpen- sive! "Free" details. COMMAND, D-176, Box 2e24, San Francisco. CA 94126. ELECTRONIC engineering. 8 volumes com* plete. $109.95. No prior knowledge required Free brochure, BANNER TECHNICAL BOOKS, 1203 Grant Avenue, Rockford, IL 61103. MAKE a thing... make a living... Study tndustrlat Design Technology and bring your ideas to life. Learn to problem-solve, sketch, render and de- sign. Develop models, create prosthetic appli- ances. 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Eeich output can sink up to 2^0 mA ^auioH^availatite 2 BNG confHctws p^ avaitat>ie aitd ufioonimitied shell coftncctcd to ground 79 99 39 99 75 99 37,99 &B.39 3.V19 • The total desigri workst.TlpDfi - tndudin^ expanded mstrumeniation, br trad board and powef supply. • I deaf for analog. di.giial arKj mrcro- procimor circuits • B logic probe circuits • Function generator- with contJnu&usly valuable s*ze. square, triangle wave lorms, plus TTL pul^ • Triple power supply otter* tijt&d 5 VDC *upp»y plus 2 variabUj outputs - -5 - VDC and -5' 15 VDC • STTLconiiMiajleL£OindicaiQn.£mli^ • PulScri • AudA eiperanentaiioii SjpeaiAf ■ Mu]t»p>« feattires 111 one comptete ti^ irtstTLEm^n saves hundirv?d» dt doOais r«eM f C-f itKtnnthial umts • Unitnuted tiMune guarantfte orr bvead- boftrd Boditets • FlitdDC«utpui *S VOC @ 1 .0 amp. rippta - 5 ifi V • Vartabl* DC Oittpul "5 - to MS VOC @ 0 5 if mp. rJpple - 5mV DESCRiPTlort 1 - IK .1 lOK and yncommFtted 0 ?S W . % u Bftadboaning area ^JCK^COmiTtEtte^ tie povnij 1 1 5" lo«g M ifi" wKJe jt 6 5" higti Input 3 ftirt; AC hrtO input (117 V. 60 Hz lyp'cal) Weight PB503 1-9 10-24 2St ?99,99 234 99 IDC BENCH ASSEMBLY PRESS COLLIMATIIIG PEN laseh diode modulc Trw P^fVj}« PV^jOS' 1 < tor i 01 A bo* pOwe* £Cp» 1-9 lO-t« 2^ STOCK £eTii±Kf co'^ltii^g Of ■ l*ter ICk3lit«kH»& comacbon 10 1 DC poii«r ti«Phr Duiigh pnt-sst b produce j par^ Mm. 1h« focal 1«ngSft mMv t» Bdjiiitied t0 tocuii Sturdy, tmiilli and s*11'C0R- tainod. irttLDMt3$tftai»tT!0)M3n [jcwice CMU^ncd Tar a wide ranae rH aifpllcnliDna 004" 'di^rri. x long STOCK. < DE^RJPTION M COLUMATIHG LENS DUAL MODE LASER POINTER barad Aai ad* at 4 haii a^ft f a«^^ r via Rl me ptacs* Oiofla in itia Icm by. bmm ta stock: ' GE:SCR1PTK)N t-S I0k34 aft* Ndw ^niliw laser pc»Dl8r>» only V | LDMtl^ J mW Ltjm Dmdt UeAM I ciMifiKrivr ■ f ^4t' im and ' 'j^v3m 2 oi . 670 rm # laas ■TfW piodicaa a fi flan ' »ach«a, cr^ htir and dni tor |Mi Kmhm rafHMyt 2 AAA fiaflcM iTflKI 17093 15369 i»fl9 iaQ«3 ie;44 iMtt 17099 m»M tf«.4» t?954 K»-Ne TUBES ^ STOCK • OESCfVPmM t.t 10^ ROB0i*IC AHM KIT POWER SUPPLY ■ Inpul 1 l5..'23ilV " Oulpul @ 2 76A STOCK* PRICE £19.99 Ftobgrn tnim ufKC conttrttid lo 5Ciefn.ii BcUQfl movie Toddy. whe^hCFf thvy'ici partorrniig dawmous U»sk.&Hpr pu]]in^ t^ft ts *A fAj^i'O'iat Hit If a9 lasMng yom own hidiq* liiilii PRICE m99 An imcsmant robot thai b!iovs hcrt ' , At ItH (DbOl »mtM an ■pfra-rflfl' baam whicTi (MiacttH o&atacit m tfontnmt ihen «Ml»nafacalfy lumt and cor:- STOClca iMV9t2 PH»C€ $4X99 ORDER LINE — (800) 824-3432 FAX ORDERS — (818) 998-7975 • INTERNATIONAL ORDERS — (818) 341-8833 • TECHNICAL SUPPORT — (818) 341-8833 ^ 13JXS MINIMUM ORDER * tJPS BLUE. 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