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11 48784

$2.50 U.S. $2.95 CANADA FEBRUARY

1 ?88

THE MAGAZINE FOR THE ELECTRONICS ACTIVIST! The _ )0. Power Play ON ! Two power supplies in one 410 OFF NE ; case with digital readout G for voltage or current.

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PIS1110 ERI 11.11 UI/. 711KIS2 PIP :Ia 11 U.rr Isles (OPIMI (On 25717 2101111 1,1t.. INt PICT SPL I I/N/ MII71 kort .,Ad EDITOR p1 177721 11151111101 1.lrt tOt1 L«l;l lit NERI MI 7175 Atli SPL 7772 LONG AL? 191577 A. UTILITIES PRINT mP 1117 17511y~r1 t SERIAI MT N IT,11. bytes ..r1 Put your home computer SPELL Vol 22172 455768 19t.. fetal STARVI I17 112 TIOVE-1 11 IIIIS ...Niel 1. ... 1 .K/TREE YEK 725152 11 3M TIMIIIY011 Ldlri1 in We cover . LETTERS overdrive! POI /PIOC 11.,1.1 - 0111 041 22711 ÈUQIOIE REPLIES 1:16.. GOV.. ACTION the most powerful PERSONAL Ente cow I TYP. I C... =PMdEwa MI ht. I T. - SHIERS ,r packages available. - C rat 110. C.

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71896 48784 8 nformatìon radio is on the air.

Before you hear about Hear Your Hometown Like it on your old radio, hear it You've Never Heard it Before. live on your Just turn it on. As easy to use new Inform- as your AM/FM radio. Instantly, ant Information Radio. you're tuned into real life adven- Whether its an all- points- tures. One touch control lets you bulletin from the State Police, emergency frequencies, select and hold police, fire and the dispatcher for the city's Fire as well as NOAA weather in- emergency broadcasts so you don't Department, an ambulance racing formation channels in all 50 miss a single minute of the action. to the hospital or a National Weath- states. All pre- programmed. This Hear the amazing Information er Service report, the new Inform- new Information Radio utilizes a Radio today. Take it home and be ant from Regency makes you a principle similar to the seek a part of the action tonight!! part of all the action... instantly. and scan feature found on expensive AM/FM radios. Breakthrough Technology. Your information radio l scans Instant Information. the public service .11VT 1 ORM.RNI channels in the area, locates BY REGENCY Informant Information Radio the active signals, locks in and uses a revolutionary new technol- broadcasts all the information Information Radio ogy that allows you to constantly right to you. With revolutionary for Real Life monitor your police, fire and TURBO -SCAN speed! Adventure CIRCLE 10 ON FREE INFORMATION CARD ahn cs Volume 5, No. 2 FEBRUARY 1988

CONSTRUCTION 26 Remote TVRO Dish Positioner -puts the focal point of your satellite dish where you want it for maximum signal strength 31 Maxwell Inductance Bridge -determine the exact value of inductance with this project 35 Power Play -put this power supply on your workbench, and you'll need no other! 4- 40 Wind Witcher- Listen to mother nature's gentle song with this hot -wire sensor electronic chime NRO Dish Positioner-page 26 43 5 x 5 Audio Switch Box -eliminate the rat's nest of interconnecting wires hidden behind your stereo equipment 111j,_,Litate' FEATURES 59 Identifying Unmarked or Obscurely Marked Logic Chips -make use of those otherwise useless logic devices 65 Getting Your FCC Radio -telephone License -what you need to know to Maxwell Inductance Bridge-page 31 legally get your own license 69 E -Z Math -Scientific Notation and Unit Conversions: clearing up milli, micro, kilo, Meg, etc. with powers aim. ,. J .. - 11 I l J ll HANDS -ON REPORTS 4---1-____:),4:i.: 34 Date Calculation Software -gives the day of the week that a particular Power Play-page 35 date has fallen, or will fall, on 49 Utility Software -Utilities are what make newcomers to personal computing appear like old hackers 61 Bytesize Calc -an on- screen calculator for those times when all the frills aren't needed SPECIAL COLUMNS 74 Ellis On Antique Radio -Firing up the Crosley 50 76 Circuit Circus- Produce the most -basic building -block circuits from inexpensive op -amps Wind Witcher-fie 40 78 Carr On Ham Radio -Why's my dial all scrunched up while yours isn't? 80 Friedman On Computers -lt takes no space to tick away the time 84 Wels' Think Tank -What to do with number two? 87 Saxon On Scanners -A scanner with a flair for the weather 88 Jensen On DX'ing -Say goodbye to that 1987 calendar DEPARTMENTS x 5 Audio Switch Box -page 43 2 Editorial -The HOE PC give -away; the votes have been tallied and the winner rewarded 4 Letter Box -where readers get involved and make things happen 8 New Product Showcase -where you'll find stocking -stuffers for the technically oriented 17 Bookshelf -take a look what's new in easy -to -read electronic reference and data books 37 FactCards -the component data and applications at your fingertips 63 Free Information Card -why waste time ?; let the manufacturer clue you in

Saxon On Scanners-page 87 1 L

Volume 5, No. 2 The Magazine for the Electronics Activist! February 1988

Larry Steckler, EHF. CET Editor -In -Chief 8 Publisher Art Kleiman, editorial director Julian S. Martin, KA2GUN, editor Robert A. Young, associate editor The winner is.... Herb Friedman, W2ZLF. associate editor ...Walter W. Schopp of Livermore, John J. Yacono, associate editor California for his construction article Brian C. Fenton, associate editor Carl Laron, WB' SLR. associate editor "Digi -lyzer IC Tester" that appeared in Byron G. Wels, is2AVB, associate editor the August, 1987 issue of Hands -on M. Harvey Gernsback, contributing editor Electronics. The Digi -lyzer offers Doris Kelly, assistant editor rapid IC checking of most logic -type Teri Scaduto, editorial assistant IC's available to the experimenter. Schopp's Digi-Iyzer Ruby M. Yee, production director Karen S. Tucker, production manager For those of you who do not recall, I ran a contest for the best Robert A. W. Lowndes, editorial article published in this magazine in 1987. The prize is an IBM associate compatible computer, which we have shipped to the winner and Marcella Amoroso, production assistant he is probably playing with it now. Jacqueline P. Cheeseboro, circulation director Arline R. Fishman, advertising director Lets do it again.... BUSINESS AND EDITORIAL OFFICES Gernsback Publications. Inc. ...and offer another computer. Why a computer? You have seen 500 -B BI -County Boulevard the advertisements, especially those on television, that say that Farmingdale, NY 11735. 516 293 -3000 report writing for is school and office simpler and has improved President: Larry Steckler the potential of the individual using a computer. This is also true Vice -president: Cathy Steckler for the professional and amateur writer. Word processing programs, spelling checkers, thesaurus, and other writing aids such NATIONAL ADVERTISING SALES (For Advertising Inquiries Only) as simple desk -top publishing programs are must items for Joe Shere MIDWEST/PACIFIC writers today. 1507 Bonnie Doone Terrace Corona Del Mar. CA 92625 714 760 -8697 So get busy.... The Paths Group ...and start producing those exciting manuscripts about features 310 Madison Ave. Suite 1804 and projects that are related to our exciting hobby. The topics New York. NY 10017 712- 953 -2121 come easy. For example, there are topics on shortwave listening, project building, scientific developments, amateur radio, computers and software, scanners, television, satellites, odd -ball .,omposition by Cover photography by Mates Graphics Herb Friedman semiconductors....I could go on and on. But, if I do, and go beyond this editorial page, I'll be entering the contest. AIA ') Start writing today.... ® Hanson Electronics, (ISSN 0703.29881 Published monthly by ...and I'll Gernsback Publications. Inc 500-B Bi-County Boulevard. Farm maybe be announcing your name next year in the tngdale. NY 11735 Second-Class postage paid at Farmingdale, NY and at additional mailing offices One-year. twelve issues subscrip- February issue. You can make it so if you begin today! bon rate U S and possessions $28 00 Canada $33 00. all other countries $35 50 Subscription orders payable to U S funds only International Postal Money Order or check drawn on a U S bank U S single copy pone $2 50 c 1988 by Gernsback Publications. Inc All rights reserved Trademark registered in U S and Canada Ponied to U 5 A

Postmaster Please send address changes to Hands -On Elec- tronics, Subscnphon Dept PO Bo. 338 Mount Morris IL 61050.9932

A stamped sell addressed envelope must accompany all submitted manuscripts and or artwork or photographs d their return is desired should they be rejected We disclaim any responsibility for the loss or damage of manuscripts and or artwork or photographs while in Julian S. Martin, KA2GUN our possession or otherwise As a service to readers Hands-on Electronics publishes available Editor plans or information relating to newsworthy products techniques and scientific and technological developments Becatse of possible variances in the quality and condition of materials and work- manship used by readers. Hands -on Electronics dI,claims any responsibility for the sale and proper functioning of readenbuill projects based upon or from plans or information published in this maoa,ne

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Hands -on Electronics, 500B Bi- County Boulevard, Farmingdale, New York 11735

No Critic Here work if the green lead is connected to the Washed Out I subscribe to a number magazines, collector of QI and the white lead to I own and operate a self-service car- ranging from Consumer Reports to Sci- ground. wash, out of which I get much enjoy- ence (the journal of the American Acad- The ASA setting for some of the the ment. A few months ago, after my dollar emy for the Advancement of Science). switch positions are also wrong. The bill changer was broken into, I decided Frankly. Hands -on Electronics is turn- positions for R8Rl3 should correspond that it was time for a steel plate over the ing out to be one of the ones I most enjoy to ASA settings of 64, 100, 125, 200, changer and a burglar alarm to boot. receiving. I just got the November issue 400, and 800, respectively. According Looking through some of your older and for some reason decided to write and to the Parts List, the values of R12 R14 magazines, I decided on the Dick -Smith say, "You people are doing a great job." should be 10K, 5K, and 5K, respec- alarm (featured on pages 62-65, of the Beautiful and extremely useful maga- tively. Also, the value of R6 (27K) is not January/February, 1986 issue). zine, more like an investment than a given on the schematic diagram. I purchased the kit from Dick -Smith subscription. Shouldn't the power switch (mis- and built a 12 -Volt DC power supply -R.A., Otter Rock. OR takenly labeled Si and not S2) be be- from Radio Shack parts. It worked great tween the battery (drawn as a capacitor) on the bench! After all of the guts were Thanks for the kind words of praise. and the rest of the circuit? mounted in a box and the installation There is something wrong with your let- I made all the above changes in the complete inside the pump house it ter. though: it's all praise. We at Hands - circuit and got it to work fine, so I think doesn't work properly. I have tried sev- on Electronics want complaints too. the answer to all my questions is "yes." eral basic fixes, but being the novice that We are in a wonderful situation here; Thanks for giving me a project to cover I am, I still can't get my act together. we get to distribute information on our both my hobbies. When the unit is switched on it trig- hobby. Almost all of us here are hob - -S.S., Idleburg, PA gers itself 50% of the time. Dick -Smith byists just like you, and we want to pro - recommends that a 331LF or 471.LF ca- duce a magazine that we would spend You're more than welcome, and you pacitor be soldered across the supply rail our own hard-earned bucks for. Many are correct in all you say. Just so our of the 555 timer to prevent this, well -it readers like yourself tell us we do just other readers know what we're talking helped some, but not completely. that, but complain a little more and about, here's a revised schematic with Another problem (or maybe part of maybe are can out -do ourselves! all the corrections. Thanks for the help. the first problem) is that fluorescent light

Idle Hands I was wondering if you had some kind NC GRN of project that I could build with my e hands like the one the man is doing in 01 02 the enclosed picture. I need that kind of a training, not just book. Books do help, sub

I q but 1 need some projects too. If you can C1 help me with this it would help me more 10 S1 in the field of electronics. RESET -D. B.. Los Angeles, CA

The photo you sent us was from one of BASE R7 R6 R9 R 0 R 1 R12 R13 our advertisements. You know how to DIAGRAMS R2 25K 425K _1 25K 25K 25K 410K 45K tR14 5K write us so why are you holding out? 2 7K

Subscribe. Look at this issue, it's loaded eÇc 125 with projects: nulf said. 100 O 200 6 2 0400 O1 o 800 2 N 697 Picture Perfect 0 0 1000 s q y R6 S3 In the November issue, concerning R3 27K ASA the article on the Flashmate, the mini- dVsub 200ft S2 O PO WER ature output transformer has one lead 02 M1 O that is not connected. Not the NC lead 0 -50 81 MA OC R5 R4 but the one below it. Where does it go 1 5 1 2 2K 2000 to? Further. doesn't the polarity of the transformer matter'! I found the unit will

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¡I OKMACHINÉMEWC INC. ONTERSILAD x 1) DRAM 150NS $5.7011; $39.95I9 ESDCWINDUSTRESÁMDEKGRE. ` VISA Fv 256K (262,144 EAC. INC. J. W. MILLER AAVID ENG NEI 4GAR YAGEO J. W. MILLER LUXO I Firsts ARIES PLESSEY - E F. JOHNSON *ATLANTIC SEMICONDUC' ^ FactoryEY 3C CHEMICALS p - - I INTEGRATED CIRCUITS 1 A N T A 1 UM CAPACITORS I 400 WOO we r r 37 cMDS - SOLDER TAIL ' t 4.00 Ñ DIP SOCKETS , - -. llll =11 - . éi .r . .. . ánCwrc á I S2 4 46 37 22

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6 CABLE EQUIPMENT PRICES SLASHED WHILE YOU weir.

Call Aunt Matilda at racmc CaMs Cs.. c.. and get a pleasant surprise: Instant price cuts even on our own cut -to- the -bone prices! Here's how: Just supply her (or one of our other operators) with anybody else's published prices (even wholesale, if you're a dealer) for the unit you want: and if their price beats our published price, we'll match v it -or even beat it! Simple as that. Of course, you'll have to look far and wide to beat our prices (see below) and we're betting that Aunt Matilda will seldom need her "little hatchet" and can partake of her cherished afternoon nap. Which is fine with us -she makes us nervous with that thing! (Not to mention our competition!)

Check our prices on scientific Atlanta Units!

1 1 10 OR 10 OR ITEM ITEM UNIT MORE UNIT MORE RCA 36 Channel Converter (Ch 3 output only) 2900 1800 MIn,code(N -12) .. 8900 5800 Panasonic Wireless Converter lour best buyl 8800 6900 Minicode (N -12) with Van Sync 9900 6200 400 or 450 Converter (manual tine tune) 8800 6900 Mlnicode VanSync with Auto On -Off 14500 10500 Jerrold 400 Combo 169 00 119 00 Econocode (minicode substitute) 69 00 42 00 Jerrold 400 Rand Remote Control 2900 1800 Econocode with VanSync 79 00 46 00 'Jerrold 450 Combo 19900 13900 MLD- 1200 -3 (Ch 3 output) 9900 5800 *Jerrold 450 Hand Remote Control 2900 1800 'MLD -1200 -2(Ch 2 output) 9900 5800 Jerrold SB- Add -On 8900 5800 Zenith SSAVI Cable Ready 17500 125.00 1400 Jerrold SB- Add -On with Tnnlode 9900 7000 Interterence Filters (Ch 3 only) . 2400 M -35 B Combo and (Ch 3 output only) 9900 7000 'Eagle P0-3 Desc rambler (Ch 3 output only) 11900 6500 M -35 B Combo unit with VanSync 10900 7500 'Scientific Atlanta Add-on Replacement Descrambler 119.00 7500

Output Price TOTAL Item CHECK US OUT -WE'LL Quantity Channel Each PRICE MEET OR BEAT THE OTHER'S ADVERTISED WHOLESALE OR RETAIL PRICES!

MasterCard VISA SUBTOTAL Californ a Penal Code #593 -0 forbids us from Shipping Add shipping any cable descrambling unit to anyone $300 per unit In residing the state of California COD 8 Credit Prices subject to change without notice Cards -Add 5% Pacific Cable Co., Inc. PLEASE PRINT TOTAL 73251/2 Reseda Blvd., Dept. H -02 Name - Reseda, CA 91335 Address - __ _ City State Zip Phone Number ( (818) 716 -5914 (818) 716 -5140 _ _

Cashier's Check : ' Money Order L : COD C Visa C Mastercard NO COLLECT CALLS! Acct R Exp Date

IMPORTANT When ordering, please have Signature the make and model number of the equipment YOU MUST SIGN AND RETURN FOR OUR RECORDS, used in your area -Thank you! DECLARATION OF AUTHORIZED USE - I, the undersigned. do hereby declare under penalty of perjury that all products purchased. now and In the future. will only be used on cable TV systems with proper *Call for availability authorization from local officials or cable company officials In accordance with all applicable federal and state laws. FEDERAL AND VARIOUS STATE LAWS PROVIDE FOR SUBSTANTIAL CRIMNAL AND CIVIL Prices subject to change without notice PENALTIES FOR UNAUTHORIZED USE.

a registered trademark Instruments Corp Dated _ Signed Jerrold is or General - 7 D DIEM

Radio Catalog hand tools, are just some of the products MFJ Enterprises. Inc.. will send you featured in this issue free their latest 24 -page Amateur Radio The wide selection of products is aug- Catalog that has over a hundred products! mented with an easy ordering system, dis- In it you'll find the most reliable and counted pricing, and same -day shipment affordable antenna tuners, filters, keyers, policy. packet radio controllers, computer inter- To receive your free, full -color copy, faces, dummy loads, antenna switches, plus a complementary year's subscrip- speaker wattmeters. noise bridges, anten- tion. Write to: Contact East, P.O. Box na bridges, antenna current probes, tun- 786, North Andover, MA 01845; Tel. ing indicators, antennas, converters, am- 617/682 -2000. plifiers, preselectors, a microphone equalizer, code practice oscillators, fre- Audio/Video Preamp From dBx quency standard, clocks, Morse code tu- The CXI Audio /Video Preamplifier can tor program. computer products, video control up to nine different audio and vid- products, power strips, RFI chokes and eo sources including a television monitor- many other unique and useful accessories CIRCLE 74 ON FREE INFORMATION CARD receiver, VCR, VDP, FM /AM tuner, CD that are available only from MFJ. player, two audio recorders, and turnta- ranges are 0 -5 Amps DC, 0 -15 Amps DC, bles with MM and MC cartridges. Three and 0 -30 Amps DC. The meters are rated variations of digitally-processed audio A for 80, 250, and 500 Watts. ambience, plus high -separation Fro Logic The retail price for the APM -70W is Dolby Surround Sound, are other major $29.30. For more information contact: DI features. Products, Inc.. 95 E. Main St., Hunt- ington, NY 11743.

Technical Supplies Contact East's latest catalog contains many new and innovative items for ser- MINCIRCLE 57 ON FREE INFORMATION CARD vice engineers, manufacturing engineers. CIRCLE 85 ON FREE INFORMATION CARD technicians, and electronic hobbyists. A A single knob selects any source for To get your free copy call toll -free full selection of test instruments, the latest recording by any of the three possible 800/647 -1800 or 601/323 -5869 or write in static and contamination protection, in- recorders. That feature simplifies dubbing MFJ Enterprises, Inc.. P.O. Box 494, spection aids, data and telecommunica- between two audio tape decks or two Mississippi State, MS 39762. tion equipment. electronic adhesives, VCRs. Outputs are provided for a video soldering supplies. Contact East's line of monitor and also for front and rear audio VolVAmp /Watt Meters tool kits and a section devoted to precision channels. Named the Model APN1 -70J k Series of The volume control consists of ganged, analog panel meters. they perform the .....k., Supplies tor Ebe.k." ,.,,. precision -stepped variable resistors that functions of three separate meters. The maintain less than I dB channel difference APM -70W meters are capable of reading contact east over the entire operating range. Sub -level DC Volts. Amps, and Watts off of a single Sams day shipment! controls permit separate adjustment of dial face. The meters are constructed with both center and rear channels. two separate meter movements within the The bass control can be switched to To Ordor, Call 617.602 -2000 same case thereby allowing continuous operate at either of two turnover frequen- and independent readings of DC voltage cies, 120 and 300 Hz. The 120 -Hz posi- and current. tion, is also ideal for bringing up the low Where the volt and ammeter needles end of smaller loudspeakers. The 300 -Hz intersect. DC power consumption can be position is useful for room equalization. read directly off the calibrated dial face, The CXI's treble control also offers a greatly simplifying the simultaneous choice of two modes. The unique tilt monitoring of all power-load parameters. mode, introduces a gentle upward or Panel space requirements are mini- downward tilt to the entire frequency mized considerably by using only one spectrum above 200 Hz. The downward meter in place of three. Meter size is 2'/4- tilt counteracts the overly bright sound of in. with a behind- the -panel depth of only some CDs and speakers. A second treble

7/x -in. All three APM -70W models mea- control mode boosts or attenuates fre- sure 0 to 30VDC. Current measuring CIRCLE 60 ON FREE INFORMATION CARD quencies above 4 kHz. can even earn your Associate in Applied Science Degree in Elec- tronics Engineering Technology. Of course, you set your own pace, and, if you ever have questions or problems, our instructors are only a toll -free phone call away. e first step is yours. To find out more, mail in the coupon below. Or, if you prefer, call toll -fiee 1-800-321-2155 (in Ohio, 1-800-523-9109). We'll send you a copy of CIE's school catalog and a complete package of enrollment information. For your convenience, we'll try to have a representative contact you CIE MAKES THE WORLD to answer your questions. OF ELECTRONICS YOURS. Today's world is the world of elec- 4K RAM Microprocessor Training tronics. But to be a part of it, you Laboratory, for example, trains you to need the right kind of training, the work with a broad range of com- kind you get from CIE, the kind that puters in a way that working with a can take you to a fast growing career single, stock computer simply can't. in business, medicine, science, government, aerospace, trsonalized communications, and more. raining. cialized You learn best with flexible training. training, so we let you choose from You learn best from a specialist, a broad range of courses. You start and that's CIE. We're the leader with what you know, a little or a in teaching electronics through lot, and you go wherever you want, independent study, we teach only as far as you want. With CIE, you electronics and we've been doing AHO-75 it for over 50 years. You can put that experience to work for you Cleveland Institute of Electronics just like more than 25,000 CIE i CIE 1776 East 17th St., Cleveland, Ohio 44114 students are currently doing YES: I want to get started. Send me my CIE school catalog including details about the Associate Degree Program. I am most interested in: all around the world. computer repair television /high fidelity service telecommunications medical electronics actical robotics /automation broadcast engineering training. other Print Name You learn best with practical training, Address Apt. so CIE's Auto -Programmed® lessons are designed to take you step -by-step, City State Zip principle -by-principle. You also get Age Area Code /Phone No. valuable hands -on experience at every Check box for G.I. Bulletin on Educational Benefits TODAY! stage with sophisticated electronics Veteran Active Duty MAIL tools CE-designed for teaching. Our CIRCLE 11 ON FREE INFORMATION CARD 11 AMAZING NEW PRODUCTS SHOWCASE SCIENTIFIC & ELECTRONIC A soundstage control allows the listener to blend the front stereo channels PRODUCTS until mono is achieved. Turning the con- PLANS-NM Yourself -AIR Parts Available In Stock trol the other way adds varying amounts of LC7-BURNING CUTTING CO, LASER S 20.00 RUM-PORTABLE LASER RAY PISTOL 20.00 L R and R L difference signals to the TCC1 -3 SEPARATE TESLA COIL front channels, increasing the apparent PLANS TO 1 5 MEV 2000 1600 width of the stage. GRA1- GRAVITY GENERATOR 10.00 EML1- ELECTRO MAGNET COIL GUWLAUNCHER _...._.. 6.00 The dBx CXI preamp provides four dif- KITS ferent digitally processed surround sound MFT1K-FM VOICE TRANSMITTER 3 MI RANGE 49 50 modes; Dolby Surround with Pro Logic VWPM5K- TELEPHONE TRANSMITTER 3 MI RANGE 39.50 BTC2X -250A0 VOLT 10-14' SPARK TESLA COIL 199.50 and three ambience modes, each individ- LHC2K- SIMULATED MULTICOLOR LASER 39.50 CIRCLE 59 ON FREE INFORMATION CARD BLS1K- 108.000 WATT BLASTER DEFENSE DEVICE Ce350 ually engineered for the highest possible ITM1K- 100.088 VOLT 20' AFFECTIVE performance. ther passive or active arming. Passive RANGE INTIMIDATOR 69 50 PSP4K -TIME VARIANT SOCKK WAVE PISTOL 5950 The CXI audio-video preamplifier will arming allows the driver to activate the PTGIK- SPECTACULAR PLASMA TORNADO GENERATOR 149.5U be sold through the select network of dBx security system automatically by shutting MVPIK SEE IN DARK KIT 199 50 dealers at a suggested retail price of off the ignition; when the ignition is ASSEMBLED $1,500. For more information contact turned on again, the system automatically PG70H- MULTICOLORED VARIABLE MODE PLASMA GLOBE "7" 199 50 dBx, at P.O. Box 1000, Newton, MA is deactivated. For the driver who prefers BTCIO- 50.000 VOLT -WORLD'S SMALLEST TESLA COL 44.50 02195. to arm the system manually, the PAS -250 161140-1MW HeNe VISIBLE RED LASER GUN 199 50 also offers active arming. TAT20 AUTO TELEPHONE RECORDING DEVICE 2450 GPV18 -SEE IN TOTAL DARKNESS IR VIEWER 349 50 Second Skin Keyboard Protectors Both models incorporate two types of LISTI O- SNOOPER PHONE INFINITY TRANSMITTER 169.50 IPOTO-INVISIBLE PAIN FIELD GENERATOR- The Second Skin is a highly flexible sensors: shock and current. The shock MULTI MODE 74.50 ultra -thin, transparent membrane that sensor triggers the alarm when the car is CATALOG CONTAINING DESCRIPTIONS OF ABOVE PLUS protects your keyboard from damage due physically jarred; the current sensor sets HUNDREDS MORE AVAILABLE FOR S1.000R INCLUDED FREE WITH ALL ABOVE ORDERS. to dirt, dust, liquids, and other environ- off the alarm when electrical devices in PLEASE INCLUDE $3 00 PH ON ALL KITS AND PRODUCTS mental contaminants. the car are activated (e.g. the dome light, PLANS ARE POSTAGE PAID. SEND CHECK, MO, VISA, MC IN US FUNDS glove box light or trunk light). Pin switch- INFORMATION UNLIMITED es in the hood and trunk also trigger the alarm either hatch is lifted when the P.O. BOX 716DEPT. HO AMHERST. NH 03031 if system is armed. Under active arming, the PAS -250 features starter /fuel pump lockout, which prevents engine start-up. The system includes adjustable entry delay, which enables the driver to set the amount of time to enter the car before the CIRCLE 80 ON FREE INFORMATION CARD alarm is activated. That can be set for anytime between one and 20 seconds. Some of its features are: it won't inter- Exit delay (the time allowed to exit the fere with keying ease or sensitivity; it vehicle after arming the alarm) is fixed at eliminates downtime due to costly key- 30 seconds. EARN YOUR board cleaning; the transparent plastic The PAS -250 features an LED status film allows clear visibility of all keyboard indicator which enables the driver to set B.S.E.E. key markings; each model is manufac- the amount of time to enter the car before tured to exactly match the contours of the alarm is activated. It can be set for DEGREE ' your specific keyboard; it resists abrasion, anytime between one and 20 seconds. THROUGH HOME STUDY tearing, and cracking; self-adhesive areas Exit delay, or the time allowed to exit the for easy and quick attachment; 22 models vehicle after arming the alarm, is fixed at Our New and Highly Effective Advanced-Place- ment Program for experienced Electronic Tech- available with more to be released soon; 30 seconds. nicians grants credit for previous Schooling and and custom tooling is available. The PAS -250 features an LED indicator Professional Experience, and can greatly re- The suggested retail is $24.95 and is which can be mounted on the dashboard time required to Program duce the complete and available through the Tech- cessories net- door. When system reach graduation. No residence schooling re- or the is armed, the quired for qualified Electronic Technicians. work of dealers and distributors. For more light blinks to let the driver-and any Through this Special Program you can pull all of information contact Tech- cessories, 3421 possible intruders -know the security the loose ends of your electronics background Helena Drive, Lake Worth, FL 33461; system is activated. together and earn your B.S.E.E. Degree. Up- grade your status and pay to the Engineering Tel . 305/439 -0909. The alarm cycle for both systems lasts Level. Advance Rapidly! Many finish in 12 30 seconds, unless intrusion continues. If months or less. Students and graduates in all 50 Mobile Security System activated, the 120 -dB electronic siren States and throughout the World. Established Over 40 Years! Write for free Descriptive Lit- The PAS -250 offers protection with an sounds and the parking lights flash. The erature. ultrasonic sensor system that blankets the security system is automatically rearmed interior of a car with inaudible sound after the alarm shuts off. OOK'S INSTITUT waves. If an intruder breaks into the car The PAS -250 includes complete wir- the force is interrupted, immediately ing, harness and installation hardware and OF ELECTRONICS ENGINEERING field activating the PAS -250's I2 -dB, very comes with a one -year warranty. 347 RAYMOND ROAD loud, electronic siren. For more information on the product cI P.O. BOX 20345 JACKSON. MISSISSIPPI 39209 The PAS -250 incorporates several lev- write to Pioneer Electronics Inc., P.O. els of protection. The system features ei- Box 1720, Long Beach, CA 90901 -1720. CIRCLE 7 ON FREE INFORMATION CARD 12 Temperature Controller An adjustable temperature controller for soldering irons, woodburning tools, and other devices with heating elements where variable temperatures are desired is available from Hot Tools, Inc. The Hot Tool Dial -Temp Controller is compatible with any soldering iron, woodburning tool, or other device which uses a heating element from 15 to 1600 watts. Simply plug the device into the the controller into any CIRCLE 62 ON FREE INFORMATION CARD controller, plug CIRCLE 68 ON FREE INFORMATION CARD 110 -VAC outlet, and set the dial anywhere between low to high as desired. diodes and transistors; identifying and The Spirig 3S -Watch combines ele- avoiding safety hazards; measuring volt- gance and permanent on -hand availability age in high -resistance circuits; using 70- of antistatic protection. The watch and series features like the audible continuity wriststrap are made of a durable special test and Autorange; Touch Hold and plastic. The electrical contact to the Range Hold; testing the meter's internal wearers skin is made by a stainless steel fuse; interpreting meter range and other inlay within the wriststrap to guarantee displays. 1(0ß/ reliable contact. The watch can be The U.S. list price for 70 Series Solu- entirely washed with a detergent to re- tions is $225. For more information, con- move any traces of grease or other contact John Fluke Mfg. Co., Inc., P.O. Box taminants which could interfere with WA 98206; Tel. contact. The coiled cord is connected to CIRCLE 78 ON FREE INFORMATION CARD C9090, Everett, 800/443 -5853. the wriststrap by a detachable snap con- Incorporating a grounded 3 -prong plug tact with a megohm resistor incorporated and plug receptacle, the Hot Tool Dial - Antistatic Wristwatch within the mold. Cord contacts of other to Temp has a I5 -A capacity. Applications Ordinary antistatic protection wrist- systems like 3M or Somco do connect include electronics assembly, carving, bands have one big disadvantage: they are the 3S- Watch. feathering, and soft shadowing with a not always on -hand when they are needed The 3S -Watch is available in a gents woodburning tool, laboratory instruments to handle some sensitive components or and a ladies model and price including the and hot plates, stained glass and crafts. assemblies. coiled cord is $59.50. The Hot Tool Dial -Temp Controller sells for $27.50. For more information contact: Hot Tools Inc., 24 Tioga Way, P.O. Box 615, Marblehead, MA 01945; LINE ZAPPER II 1 Tel. 617/639 -1000. VIDEO TAPE COPY PROTECTION GOT YOU DOWN? Course for DMM Use STABILIZE YOUR PICTURE Here's a video training product de- WITH THE signed to maximize the usefulness and Employers LINE ZAPPER II safety of Fluke's 70 Series of handheld digital multimeters (DMMs). The product, titled "70 series Solu- Willing workers available the tions," is intended for industrial or voca- The Line Zapper II stops flashing, brightness changes, jumping, and jittering now at as little as 'Vs caused by the Macro-Mess. Just connect in the direct video line between two VCR's tional training applications. In addition to your usual cost. or between a VCR and a monitor. the I5- minute video tape, it includes nu- This is your chance This unit works like a video watchdog, and when it sees an interfering signal it to get help you've zaps it, giving you a normal, clean signal at its output. merous classroom tools such as overhead needed, but thought you The complete kit is only 559.95 plus $4.00 shipping (not recommended for the transparencies, a 100 -page Instructors couldn't afford. beginner). Available assembled and tested at 599.95 ea. plus $4.00 shipping and comes with 1 year warranty. Guide, and 25 Student Workbooks. No business too large or too small. Call your The training emphasizes "hands -on" private industry council exercises. A minimal amount of theory is or write National DECODE NEARLY ANY SINGLE LEVEL GATED PULSE SIGNAL presented. Instead, examples of how to Alliance of Business, PO. Box 7207, This new circuit works with Hamlin, Sylvania, Eagle, and Jerrold (not for tri- make a wide variety of basic measure- Washington, D.C. 20044 mode) systems. Decodes In -band, Out -band, AM or FM reference signal (must be ments accurately and safely are given by used with a downconverter). 40 page gated pulse theory booklet demonstration. Many of the unique fea- 515.00 (IPFD -1P), PC board tures of the 70 Series DMMs are also 515.95 (IPFD -1B) or complete educational kit including book, PC explained. board, case and parts (IPFD -IK) Subject matter includes: AC and DC only 547.00 plus 54.00 shipping. mak- Voltages and how to measure them; A Public Sow* al A ins PWiuem , ing sinewave (RMS), non -sine wave, and Please allow 6 weeks for delivery. composite voltage measurements; current Canadian orders please add 52.00 extra for shipping. MC and Visa and how to measure it; resistance and how accepted. to measure it; preventing damage to the ELEPHANT ELECTRONICS meter or circuit during test; why a meter P.O. BOX 41865 indicates in- circuit resistance that is dif- PHOENIX, AZ 85080 ferent than what's indicated by the resistor (602) 581 -1973 color code; testing and troubleshooting of 13 For further information write to Solder Absorbing Technology Inc., 144 Oakland Street, Springfield, MA 01108; Tel. 800/628 -8862.

Data Generator Someone saw the great need for a versatile tool for testing printers, CRT's, modems, and designed and manufactured the data generator, model 232DG. The CIRCLE 70 ON FREE INFORMATION CARD data generator outputs ASCII data in various combinations of line length, baud The units utilize a gas -filled discharge rate, parity, number of stop bits, and word element, and a secondary stage to provide length. the output may inhibit via Data CIRCLE 82 ON FREE INFORMATION CARD double protection to the equipment. The Terminal Ready (pin 20), or Request to units restore themselves time and time Send (pin 4), or by X -on and X -off. The Also, an optional AC power supply is again for repeated use. status of Clear to Send (pin 5), Data Set available that could be utilized to replace The "High -Tech Arrestors" divert un- Ready (pin 6), and Carrier Detect (pin 8) the battery. wanted surges (such as lightning) away all may be controlled by using the various The Model 232DG RS -232 data gener- from the equipment to a safe ground. switches. ator retails for $199.95 and the Model Rated up to 2000 watts for transmitters, The B &B data generator in the ASCII 232PS Optional AC Power Supply for they are available with UHF, BNC and N mode produces all of the printable ASCII $14.95. type connectors. Prices for the units start characters including space; a 2716 prom is For more info write: B &B Electronics at $29.95. For more information contact used to store those characters and may be Mfg. Co., 1500 Boyce Memorial Drive, Spi -Ro Manufacturing, Inc., P.O. Box reprogrammed for custom test patterns or P.O. Box 1040, Ottawa, IL 61340; Tel. 1538, Hendersonville, NC 28793. used for sending messages. 815/434 -0846. The unit in the U -U -Mode outputs the Epson Printer Buffer letter U constantly. That is a square wave Surge Arrestor Image Technology Inc. now offers an at one -half the selected baud rate and rep- These High -Tech Arrestors protect inexpensive, large- capacity print buffer resents a good worst -case test. The Output transmitters, transceivers, receivers, base that mounts inside your Epson printer. Switch will allow you to output data on stations, etc., from any harmful damage The buffer allows you to transfer data to pin 2 or pin 3. The 232DG uses a 9 -volt caused by lightning surges, transients, the printer at computer speed and get back battery (not included with data generator). etc. to work immediately while the printer operates at its own pace. It's much more economical than buying a faster printer to W *QUALITY PARTS *DISCOUNT PRICES * FAST SHIPPING SEfp FOA increase productivity. 98rcÇE OG... 1LL ELECTROAICS CORR 48 PAGES' ECTROi-, CORR A defense BLACK LIGHT sj _ , 1mA METER r against cancel' ASSEMBLY - Modutec 0 -1 mA signal strength meter with HLM logo. can be C(x)kled up Complete, functioningr`? 1/4" X 1 3/4" X 7/8" deep. in your kitchen. assembly includes ballast, on -off switch CATO MET -2 $2.00 each power cord, sockets and F4T5 -BL blacklight. Mounted on a 7 1/8" X 3 1/8" metal plate. Use VIC 20 MOTHERBOARD for special effects lighting or erasing EPROMS. ATE BLTA 10.0 There is evidence that SWITCHING POWER SUPPLY diet and cancer arc related. Follow these modifications Compact, well in regulated switching power your daily diet to reduce supply designed to power Texas Instruments 26 IC's including 6502A and 6560. Not chances of getting cancer computer equipment. guaranteed but great for replacement CIRCLE 53 ON FREE INFORMATION CARD I. Eat more high -fiber foods INPUT: 14 -25 vac 0 1 amp parts or experimentation. such as fruits vegetables OUTPUT: 12 vdc 0 350 me. CAT vim_sn tison and and whole-grain cereals. 5 vdc 0 1.2 amp Some benefits: works Ep- -5 vdc p 200 ma. XEON FLASH TUBE 2. Include dark green and it just like SIZE: 4 3/4" square. 3/4" X 1/8" dia. deep yellow fruits and vegeta- son's optional buffer but has much more CATE PS -30 $3.50 each CATI FLT-1 2 for $1.00 bles rich in vitamins A and C. capacity and costs less; it simply plugs THIRD LED S MINI 3. Include cabbage, broccoli, brussels sprouts, kohlrabi and TAIL Jumbo T 1 -3/ TELEPHONE no LIGHT 4 BUTTON cauliflower. inside your printer, wires or controls (5 mm) S.P.S.T. COUPLING Sleek RED momentary. 4. Be moderate in consump- required; it works automatically every high -tech TRANSFORMER tion of salt-cured, smoked. and CATI LED - 1 Push to make. time you print, one board provides 64K, lamp 10 for $1.50 CATE MPB -1 nitrite -cured foods. Stuns 600 ohms assembly. Cut down on total fat in- 128K, 256K or 512K (300 + pages); it fits 10 for $3.25 TTCP -8 C.T. 5. Could be GREEN to take from animal sources and NI 600 ohms used as a CATI LED -2 -CAD CHÁ GER/ fats and oils. most Epson dot -matrix parallel printers; it third C.T. P.C. auto 10 for 82.00 TESTER 6. Avoid obesity is warranted year; is tail emegency board mount. for one full It always light, Will charge most warning light, or YELLOW 3/4" X 5/8" 7. Bc moderate in consump- expandable to 512K. every size Ni -Cad :.ccrcn tion of alcoholic beverages. special- effects lamp. CATE LED -3 X 3/4" battery available. CATE Red reflective lens 10 for $2.00 TCTXS The unit comes as three different kits: CATE UNCC -N 615.00 $2.50 is 2 3/4" X 5 1/2" OK bytes for $109.00 (you furnish the is mounted on a 4" TWO PIECE RECHARGEABLE NI-CMS BATTERIES No one faces high pedestal with HOLDERS cancer alone. chips); with 256K at $133 (in- AAA SIZE 1.25V 1801nAH $2.25 DRAM up -down swivel ad- FOR óaéD jrMNIVGN CANON $OQTY ABOVE AA SIZE 1.25V 500mAh $2.00 justment. Includes 1..E.D.S cludes 8 256K RAM chips); or 512K for AA WITH SOLDER TABS $2.20 12 V replaceable bulb CATE BLED C SIZE 1.2V 1200mAH $4.25 $157 (includes 16 256K RAM chips). 10 for 65c SUB-C SIZE SOLDER TABS $4.25 CATO TLB $3.95 100 more contact: Image each for $5.00 O SIZE 1.2V 1200mAH $4.25 6-v-) For information Technology, Inc., 8150 S. Akron St., pv.,m0 u. ,Tro TOLL FREE ORDERS OUR NEW ADDRESS IS: Suite 405, Englewood, CO 80112; 800 -826-5432 CAI, P.O. BOX 567 r . INFO (818) 904 -0524 t Te1.303/799 -6433. FAX - (818) VAN NUYS, CA 91408 781 -2653 I °:,KSUFFICIENT p v SNIPPING 14 CIRCLE 5 ON FREE INFORMATION CARD Multi- function CD Player Each ring is made of a rubber -like com- New functions differentiate the Revox pound, and attaches to the back side of Signature CD player. Those include a Pre- any CD with an easy -to -use centering de- Free vious mode which allows the previously vice. Using centrifugal force, the ring Famous hi-tech played track to be repeated; an Index con- flattens the rotating disc. That in turn re- atalog trol that provides direct numerical access duces rotational flutter and allows the to indices on a CD via the remote control, laser to read more bits of information. and remote /direct level control of the Sig- The rings sell for $19.95 for a package A very special nature's variable level output. of 15, and are available through the Sims guide to what The commemorative Signature CD distributors. For more information write the exciting world player features 16-bit quadruple oversam- to: Sims Vibration Dynamics, 2797 152nd of computer and pling and a large LCD panel which con- Avenue, N.E., Redmond. WA 98052. electronics kit - stantly keep users informed of the CD building can Iron players' operating status. Industrial Soldering do for you. Designated the New SA-8 Series, these lightweight production - irons are slim, The informative Heathkit Catalog shows heat quality irons. With a silicone- rubber you more than 450 exciting electronic prod- guard allowing the grip to remain at a ucts that will challenge, instruct, and enter- constant low temperature, the SA-8 series tain you. You'll find countless kits that you make a definite statement in quality and can build and enjoy, from computers and comfort. robots to color Maximum operator control and ac- tv's and a variety of CIRCLE 76 ON FREE INFORMATION CARD curacy is achieved by the short distance home products. And each is backed The limited edition Signature CD play- from grip to soldering surface which by our years of speeds up the soldering process. The short er can be random -access programmed experience and re- -41111114110,7 with up to 19 selections for playback in heat -up time and efficient temperature our promise, any desired sequence. Sections of a spe- covery assure the operator of quick and "We won't let cific musical selection can be played at easy handling of all the usual soldering you fail" will, with fast access and search time from applications. Start up from Pause is any starting point. IBM -PC just 0.6 seconds. Compatible Expandable Three newly -developed large -scale in- Computers tegrated circuits (SAA 7210, SAA 7220, TDA 1541) are responsible for all demod- HERO' 2000 en- Educational ulation, error correction, basic and Robot and hanced interpolation, digital and phase - Courseware linear filtering, as well as I6-bit digital -to- analog conversion. New adaptive error correction selects the best error correction strategy (from 60 CIRCLE 84 ON FREE INFORMATION CARD possibilities) to greatly improve performance on dirty or damaged discs. The irons offer: highly accurate tem- Suggested list price is $1,600 including perature stability which prevents damage remote control module. For additional in- to boards and components, quick heat up formation contact: Revox Hi Fi Products, time with rapid temperature recovery, sil- Studer Revox America Inc., 1425 Elm icone rubber heat guard which provides Hill Pike, Nashville, TN 37210. operator comfort and a positive grip for safety, long -life corrosion -resistant tip, grounded tip for CMOS safe soldering. The SA-8 Series solder irons have a maximum equivalent rating of 30, 40 and 50 watts. All irons have a three wire grounded power cord. Prices start as low as $24.95. For more information contact: O.K. In- dustries Inc., 4 Executive Plaza, Yonkers. NY 10701; Tel. 800/523 -0667 or Send NOW fort 914/969 -6800 (in New York). over A your FREE 7 Heathkit Catalog. Send to: Heath Company. Dept.107 -612 Benton Harbor. Michigan 49022

Name

CIRCLE 51 ON FREE INFORMATION CARD Address CD Rings What is it? The Sims CD Ring is an City State Zip A subsidiary of Zenith Electronics Corporation CL -784R3 inexpensive and ingenious means of producing cleaner and harmonically fuller Heathkit' sound from all CD players. Heath Company L J15 CIRCLE 13 ON FREE INFORMATION CARD BUILD -IT BOOKS Metal Detector The 1225 -X is Fisher's answer to many FOR EXPERIMENTERS requests for a lower-priced detector with Mod* rrr Vy a' BP106- MODERNOP- top performance 1225 Protects and no frills. The -X AMP PROJECTS .... goes just as deep and rejects trash just as 55.00. Wide range of build - it projects that use op- well as the higher priced 1235 -X. In fact amps. Easy to build board it's almost equal to the $500 1265 -X layouts provided for most. A variety of projects of all model, but it doesn't have a lot of extra CIRCLE 73 ON FREE INFORMATION CARD kinds are included. features. For example the 1225 -X doesn't See have built -in recharge circuitry, dual dis- and copying a WIAW RTTY bulletin on crimination modes nor is it convertible to 40 meters with the push of a button. #223- PROJECTS a body mount. It is however, a silent run- A Signal command causes the Pack -Kit USING THE CA3130 .... 55.00. 50 different ways to ning, slow- motion VLF-discriminator to determine current RTTY, ASCII, or put this op -amp to work in- with a no- motion pinpoint mode and the AMTOR mode for the signal the amateur cluding audio. RF. test equipment, household and ability to work well in mineralized soil. is listening to. It also presets baud rate, miscellaneous protects. mode, and will invert the signal if necessary. All the user does is type "OK." No special software is required to operate the HK-232 Pack -Kit TNC. It can be 4 BP44 -IC 555 PROJ- ECTS.... 55.95. Included used with any modem communication are basic and general timer package you may already have or an op- circuits. automobile and model railroad circuits. tional program written specifically for the alarms and noise makers. HK-232 and a Heathkit/Zenith PC or PC- as well as a section on 556. compatible computer. It connects to a ter- 558. and 559 timers. minal or computer through a standard RS -232 serial port at baud rates from 300 .0CNIOS t .nasa. to 9600. #224 -50 CMOS IC The retail price for the 232 is $279.95. PROJECTS .... $5.25. CIRCLE 65 ON FREE INFORMATION CARD These IC's are suitable for For more information about the HK -232 an extraordinary range of The 1225 -X has only two knobs and a Mutli -Mode TNC, write to Heath Corn - applications. This book shows you just how much push button, weighs only 3. I pounds and pany, Dept. 150 -945, Benton Harbor, MI you can do with them. like all Fisher "X" detectors, is backed by 49022. In Canada, write to Heath Compa- a Five Year Limited Warranty. Suggested ny, 1020 Islington Ave., Dept. 3100, list price is $299.95. For a free 1225 -X Toronto, Ontario, M8Z 5Z3. S.cond Book« CMOS IC spec sheet, write: Fisher Research Labo- Proj.cts 4 BP59 -2ND BOOK OF ratory, Dept. HOE. 1005 I Street, Los CMOS IC PROJECTS... . VHF Antenna Tuners 55.00. Still more ways to Banos. CA 93635. MFJ Enterprises, Inc. is introducing use these versatile devices. VHF None of these protects over- two dual band antenna tuners that lap those in book #224. Terminal Node Controller cover both the 144 -MHz and the new The pair make a wonderful The Heatlikit HK -232 Pack -Kit Multi - Novice 220 -MHz bands. They both han- circuit reference set. Mode TNC kit is a hard working addition dle 300 watts PEP and match a wide range to an expanding Amateur Radio line. It's of impedances for coax -fed antennas. MAW ideally suited for Novice Amateur Radio Both are built into rugged all- aluminum BP84- DIGITAL IC PROJECTS .... 55.25. Operators who now have digital priv- cabinets and are painted eggshell white Both simple and more ad ileges, for amateurs already involved in with a black top. vaned projects to help the Packet Radio who desire a product with The MFJ -921 has a built -in reader develop a knowl- SWR/Watt- edge of the workings of digi- multi -mode capabilities, or for amateurs meter, measures 9 x 2 x 3 -in. and retails tal circuits. A number of interested in Packet, a new mode. for $69.95. board layouts are included The Pack -Kit TNC takes the challenge out of getting into RTTY, lets users run CW at speeds from 5 to 99 words -per- MAIL TO Electronic Technology Today Inc. minute and works on AMTOR, ASCII, PO. Box 2.1i, HF, Massapequa Park. NY 11762 -0240 and VHF Packet. It can even decode Weather Facsimile SHIPPING CHARGES IN USA & CANADA an $0.01 to $5.00.... $1.00 $30.01 to 40.00... $4.75 pictures onto Epson -compatible $5.01 to $10.00 ...$1.75 $40.01 to 50.00...$5.75 printer. The Multi -Mode TNC works $10.01 to 20.00...$2.75 $50.01 and above $7.00 Packet error-free in both HF (300 baud) $20.01 to 30.00...$3.75 and VHF (1200 baud or up to 9600 baud OUTSIDE USA & CANADA with an external modem). Multiply Shipping 2 for mail by sea Adding the HK -232 to a radio and com- CIRCLE 55 ON FREE INFORMATION CARD Multiply Shipping by 4 for air mail Total price of merchandise $ puter lets the amateur get on the air in The MFJ -920 measures a compact 4 -1/2 Shipping (see chart) S every mode. It connects to the radio's PTT x 3 -in. and retails for $49.95 Subtotal $ line, speaker output and microphone in- Both the MFJ -921 and the MFJ -920 Sales Tax (NYS only) $ put for interchangeable VHF and HF op- come with a one year unconditional war- Total Enclosed $ eration. The same connections work for ranty. Name all other modes including CW. For additional information contact MFJ at P.O. Address Amateurs can connect both their HF Enterprises, Inc., Box 494, Mis- and VHF rigs at the same time which sissippi State, MS 39762; Tel. 800/ City State Zip allows switching between VHF Packet 647 -1800 or 601/323 -5869. L. J 16 IBM PC Shareware: PC -File. most current versions of the programs, PC- Write. PC -Talk and IBM PC the complete, printed documentation, SHAREWARE and the right to acquire updates of the ExpressCalc PCFItE, PC -WRIT} R. PC -TALK AND programs free or at reduced cost. This By John Ottensmann FXPRESSCALC As the prices ut personal computing user- supported software offers an af- systems fall, more and more people are fordable alternative to high -priced com- discovering just how useful microcom- mercial programs. puters are -at work, at school, and at Four programs have emerged for use home. But the PC itself is just the be- on IBM PCs and compatibles, which ginning. In order for personal comput- together constitute a low -cost, compre- ers to be able to perform useful work, CIRCLE 98 ON FREE INFORMATION CARD hensive set of software tools that will they must first be equipped with soft- fered to the public free of cost -users fill most of the needs of the average ware -such as programs for word proc- are actually encouraged to take copies computer user: essing or data management. However, of the programs and share them with PC- File -a database manager for in- unlike the prices for microcomputers, others. If users like the programs, they formation storage and retrieval; PC- the cost of software is high -and ris- are asked to send voluntary contribu- Write-a word -processing program that ing. tions to the programs'developers. In ex- is quick and responsive, allowing easy This book describes a software con- change for these very modest contribu- text editing and flexible formatting; PC- cept called shareware. Shareware is of- tions, users are entitled to copies of the Talk-a communications program that

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HO -11 CIRCLE 9 ON FREE INFORMATION CARD 0 17 OPPORTUNITY enables the PC to interact with remote computers, such as electronic bulletin boards; and ExpressCalc -an electronic WITHOUT RISK. spreadsheet program for data analysis. Those high -quality programs are covered in detail in four separate chapters, The biggest improvement in and a fifth chapter addresses using the 40 years has made U.S. Savings programs as an integrated package. The Bonds an ideal investment. PC -DOS operating system for IBM PCs A variable interest rate lets is also discussed, and an opening chap- you share in rates offered by ter provides a general background on CIRCLE 77 ON FREE INFORMATION CARD today's securities market. No limit user -supported software, with complete on how much you might earn. information on how to obtain these use- Learn how to create customized What makes this improved ful programs. The book also includes Xywrite features that enable you to Bond ideal is that you're protected an index for easy reference and many change startup and help files, the printer by a guaranteed minimum. And if detailed illustrations. file, and the keyboard. You'll also find the Bond is held to maturity, you'll With this much -needed addition to an entire chapter on programming double your money. the surprisingly scarce documentation Xywrite and four chapters on printing Take another look at this currently available, everyone can tap techniques. opportunity without risk. into this economic and attractive source Using ZyWrite Ill covers everything of microcomputer software. you need to know for complete ZyWrite IBM PC Shareware: PC -File, PC- mastery. Take; Write, PC -Talk and ExpressCalc con- The book contains 374 pages. cost- _? tains 256 pages, and costs $15.60 in ing $ 1 7.95 from Osbourne/McGraw - Stock `BGS paperback from Tab Books Inc., Blue Hill, 2600 10th St., Berkeley, CA Ridge Summit, PA 17214; Tel. 717/794- 94710; Tel. 415/548 -2805. ifAmerica. 2191. The Robot Builder's Bonanza: 99 A public service of this publication Using Xywrite III Inexpensive Robotics Projects CI and The Advertising Council. By John Sladek By Gordon McComb From beginning steps to advanced ap- A unique collection of tested and prov- plications, Using Xywrite III quickly en project modules that can be mixed and Motion Control & brings you up to speed on ZyQuest's matched to create a wide range of highly Data Acquisition word processing software for the IBM intelligent and workable robot creatures. on your IBM PC orApple I I and all compatibles PC and PC- compatibles. Operating in- Probably no other area of electronics structions for both XyWrite II and generates more enthusiasm and interest XyWrite III are thoroughly described. in hobbyists than does personal robot- Begin with basic writing, editing, for- ics -and it is no wonder. Building a matting, and printing. As you work through sample applications and exer- Smart 2 Axis Motion Controller. For many cises, Sladek discusses such sophisti- of motors & encoders. New I.C. (from HP) allows changes & monitoring on the fly. Optically cated features as: windows, footnotes, isolated W /SOFTWARE $450. indexing, mail merge, math functions, Four Axis Stepper Driver. With SOFTWARE & motor for instant automatiioon. $95. column formats and programming char- Fast ts gain, 650 4 $220. rComP ete Scoppe hardwae & SOFT acter sets. WARE $500. Also: 12 Bit ND, Relay Driver, Real Time Clock Circuit developers Project Book $25. Circuit Development & Education CIRCLE 98 ON FREE INFORMATION CARD Build your own applications working circuits. robot from a collection cf in- Chips can con- animate solenoids, wires, motors, and nect directly to assorted electronic odds and ends can cable. be a thrilling experience. But-until Order our now ProjectBook and -most books on designing and build- disk with 10 chap- ing a robot have concentrated on mak- ters of circuit interfacing and SOFTWARE. ing just one model automation, with very How do you do it? Use our Local Applications little leeway for individual creativity. Bus, LAB 40.One host adapter ($95. ) supports up to 8 boards, like those above, on a 50 ft. This book is different. Gordon ribbon cable. McComb, writing in a clear, lively style, Please call (415) 755 -1978 for f ree literature takes a "cookbook" approach to build- (omputer óñtinuum "Another computer malfunction!" ing robots. That is, readers will build 75 Southgate Ave.. Suite 6 each "ingredient" separately, which they Daly City. CA 94015 (415) 755 -1978 18 VOnly NRI gives you a 27" high -resolution stereo color TV you build to prepare you for today's video servicing careers.

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Inside Your TV The Heath /Zenith 27" TV has all the features that allow you to set up today your complete home video center of the future. Flat screen, square corners, and a black matrix to produce dark, rich colors ... even a powerful remote control center that Become one of America's most sought - kets that are just starting to boom. gives you total command of video and audio after technicians ... put your talents Here is your chance to become a fully qualified professional the way tens of operating modes. and spare time to work for you in the thousands have trained with NRI. NRI has purposely designed your train- "explosive- growth" world of home ing around equipment that has the same entertainment electronics. Totally Integrated high -tech circuitry you'll encounter in com- Hands -On Training mercial equipment. That means your train- Train in state -of- the -art video /audio serving is real -world training. icing and become a fully qualified service Since NRI training is built around "learn professional the uniquely successful NRI by doing," right from the start you con- Your NRI Training way. It's hands-on training, at home ... duct important experiments and tests with Has Another Special Element your professional digital multimeter. You designed around the latest electronic equip- built into your NRI training is the the remarkable NRI Discovery Lab Also ment you build and keep as part of your assemble enormous experience of our development and perform a complete range of demon- training. instructors. Their long - strations and experiments in the process. specialists and The High -Tech Revolution proven training skills and personal guidance come to you on a one -to -one basis. in the Home Is Just Starting Always available for consultation and help, Sweeping changes are taking place in our these instructors ensure your success both homes, changes brought about by the during your training and after graduation. phenomenal growth of home entertainment electronics. Already available are high res- Step Into the Future Today olution TV, TVs with stereo sound, simul- The richest reward gained from your NRI taneous multi -channel viewing, projection Video /Audio training is a firm grip on the N Camcorders, 8 mm video cassettes, and future. Now is the time to act. Send the compact disc players. post -paid card to us today. You will receive And the revolution has spread to the busi- our 100 -page catalog free. It's a fascinat- ness sector as tens of thousands of coming explanation of our training methods panies are purchasing expensive high-tech and materials. (If someone has used the video equipment used for employee train- card, write to us at the address below.) ing, data storage. even video conferencing. Join the Future or Be Left Behind Today the consumer electronics industry ArM, School of Electronics represents a whopping $26 billion oppor- NRTs conuniuuent to you goes beyond pro- McGraw -Hill Continuing tunity for the new breed of consumer viding you with equipment appropriate to Education Center electronics technician. the latest technology. Best of all, we ensure that in the learning process you acquire the 3939 Wisconsin Avenue, NW :viol Today's consumer electronics revolution very skills that will make you a professional is creating huge servicing and repair mar- service technician on the job. Washington, DC 20016 I Í 21 BOOKSHELF Technicians, may then mix and match to create their Get Serious own unique projects. The 99 different About Your robot components described in this ingenious guide can be combined in an Profession almost endless variety of intelligent and workable robots of all shapes, sizes,

Being a certified electronics techni- and abilities. Rolling robots, talking ro- cian lets people know that you are bots, robots that vacuum, serve drinks, a professional in your field. It tells teach the kids, protect the house against them that you are serious about your CIRCLE 98 ON FREE INFORMATION CARD work and can perform up to CET fire or intruders, anything is possible standards. using these projects and a little imagi- nisms, and input/output. The final chap- nation. Now you can order the "Study ters rounds out the text with a discussion Guide for the Associate -Level CET Projects are geared to beginning and of computer networks, first defining Test" from the International Society intermediate hobbyists, and include sche- them, and then introducing possible to- of Certified Electronics Technicians. matics, parts lists, diagrams, and de- pologies, the ISO It includes material covering the OSI reference model, most often missed questions on the tailed instructions for constructing each physical transmission, protocols, and Associate CET exam. 8h" x 11 ", of the essential building blocks of the routing. paperback, 60 pages. typical personal robot: the body and A great reference for the computer frame; power and locomotion; append- professional who needs a quick review For More Information Contact ages; eyes, ears, and mouth; naviga- of a particular topic, the book covers ISCET, 2708 W Berry, Fort Worth, TX tors; and electronic control. How they the 76109. 18171 921 9101 spectrum of computers -micros to are all put together is up to the reader, mainframes -explaining architectural fea- NAME but McComb has included four com- tures like pipelineing and associative ADDRESS_ plete designs, as well as several alter- stores. And discussions are not restricted CITY STATE natives. And there are complete lists to a particular processor. To make the ZIP of sources for electronic and mechani- book as flexible and widely useful as copies @ 5514 $1 postage.) cal parts, lists of tools and equipment, possible, examples illustrating each of send matenal about ISCET a handy guide for matching up TTLs the principles are drawn from a variety and becoming certified. and ICs, a bolt and drill bit chart, and of computers. And student -tested review computer program listings for additional questions at the close of each chapter control switches for the finished droids. ensure that readers will gain a good grasp This is a fascinating guide for lay of the material. readers that emphasizes fun while it Highlights include: Basic Concepts teaches the basic principles of robotics. of Computer Systems, Digital Logic and And it is a practical guide for hobbyists Integrated Circuits, Peripherals, File that enables them to create inexpensive, Store, Numbers and Character Codes, custom designed, intelligent robots at Memory, Machine Codes and Address- home. ing Techniques, The Central Process- The Robot Builder's Bonanza: 99 In- ing Unit (CPU), Interrupts, Data Trans- expensive Robotics Projects contains 336 fer, Computer Systems, Data Transmis- pages at $14.60 in paperback from Tab sion, Communication Protocols, and Net- Books Inc., P.O. Box 40, Blue Ridge work Types. Summit. PA 17214; Tel. 717/794- Computer Architecture and Commu- 2191. nications has 288 pages costing $16.60 paperback. Computer Architecture and It is available from Tab Communications Books Inc., P.O. Box 40, Blue Ridge By Neil Willis Summit, PA 17214; Tel. 717/794- 2191. Technical managers, computer science students, and all other advanced begin- Turbo Prolog Primer ners will find this book, based on the By Dan Shafer author's successful course material, to This is an introductory text for both be an quality overview of computer ar- new and experienced programmers who chitecture and communications. Begin- want to explore the power of Prolog ning with a general introduction, Neil and expand their knowledge of artifi- Willis first defines the basic concepts cial intelligence and expert systems. of computer systems: processors, mem- Written by Dan Shafer, this 350 - ory, peripherals, backing store, logic page primer introduces the language of gates, and communications. Then the artificial intelligence -and examines the structure of a simple processor system new Version 1.1 of Turbo Prolog. It is explained, covering file store, ma- carefully examines the elements of the chine codes, the CPU, interrupt mecha- language, including how programming

22 CIRCLE 6 ON FREE INFORMATION CARD explained in the book is Intelligent As- check single words or entire documents. sistant, Q & A's natural language inter- Readers will learn how to use each of face. Intelligent Assistant allows Q & Q & A's modules- Write, Report, File, A users to issue commands or ask ques- Utilities, and the Intelligent Assistant. tions in plain English, rather than in Bolocan leads readers through each code. Another feature readers will learn feature, beginning with the most basic how to use is Q & A's programming information needed by novices, such language, which enables users to write as creating and editing a database. Top- short programs that will execute lengthy ics for intermediate readers are next ad- commands at a single keystroke. Q & dressed, such as generating reports and CIRCLE 95 ON FREE INFORMATION CARD A also includes a word processor, ideal modifying a database structure. Finally, in Turbo Prolog differs from program- for generating mailing labels and form advanced topics are introduced, such ming in other, more traditional languages letters, and a spelling checker, that will as developing macro programs, merg- such as Pascal or C. Prolog Toolbox, detailing how its routines can be helpful in developing programs. 'our Career in ELECTRONICS or COMPUTERS Topics covered include: getting to know Turbo Prolog, the Turbo Prolog Put Professional Knowledge and a Grantham College of Engineering is Editor, the structure of a Turbo Prolog a specialized institution catering to Program, making logical connections, :OLLEGE DEGREE mature individuals who are employed creating a full Turbo Prolog Program, in your Technical Career through in electronics and allied fields such as arithmetic and structures in Turbo computers. These fields are so enor- Prolog, strings and type conversion, HOME _a mous that advancement opportunity screens and windows, sound and graph- is always present. Promotions and ics, databases in Turbo Prolog, control- BTU DY natural turn -over make desirable posi- ling the program flow, and compiler tions available to those who are pre- directives. pared to move up! No. 22615, Turbo Prolog Primer, Advancement in your career is made Revised Edition, retails for $19.95 and easier and more certain by ( I) superior is available at bookstores, electronics (MI knowledge and (2) documentation of distributors or direct from the publisher that knowledge both of which are SAMS, 4300 W. 62nd Street, Indian- - obtainable through Grantham distance apolis, IN 46268; tel. 317/298 -5400. No commuting to class. Study at your NHSC. own pace, while you continue on education, fully accredited by O & A Simplified your present job. Learn from easy-to- Grantham's home study (distance ed- By David Bolocan understand lessons, with help from ucation) programs leading to the Q & A is the first successful software your instructors when you need it. package to use artificial intelligence tech- Grantham offers two B.S. degree pro- B. S. DEGREE niques in a database. A bestseller on grams - one with major emphasis in may fill an important need for you. Softsel's Hot List, this trend- setting soft- ELECTRONICS and the other with These are comprehensive correspond- ware has caused major changes in the major emphasis in COMPUTERS. ence programs in which you first review database industry. Now, David Bolo - Either program can be completed by some things you already know, in can, author of many bestselling com- correspondence (also known as "dis- preparation for the studies that come puter guides, including Lotus 1 -2 -3 Sim- tance education"), NHSC accredited. later. Some previous knowledge in plified-2nd Edition, , has written the The sooner you get started, the sooner electronics is presumed, but is thor- complete how -to guide for learning ver- you can be ready to benefit from greater oughly reviewed in depth, so as to give sions 1 and 2 of Q & A. knowledge and your B.S. degree. you a thorough foundation for the Among the many features of Q & A Our free catalog gives full details of level of studies you have not previously both degree programs. For your copy undertaken. Even though some stu- of the free catalog write to the address dents hold associate degrees before en- shown below, or phone (213) 493 -4422 rolling, an A. S. Degree is awarded (no collect calls); ask for Catalog H -2 along the way toward the B. S. Degree. For full information, write for Catalog il -? Grantham College of Engineering 10570 Humbolt Street P. 0. Box 539 "Hey, kid can 1 interest you in some eighth -grade software ?" Los Alamitos, California 90720

23 TV, RADIO ing File and Write documents, and im- PC and Macintosh desktop publishing COMMUNICATIONS porting and exporting data. Practical ap- systems, and a careful evaluation of ap- BP91- -INTRO TO RA- plications are included throughout the plications for desktop publishing and DIO DXING .... $5.00. Ev- book to help illustrate each topic. Those typesetting. erythA t you need to know about radio DXing and how include a mailing list, general ledger, The Illustrated Handbook of Desk- you can get into this fas- and a property database. cinating hobby area. top Publishing and Typesetting has 784 All commands and functions are pre- pages costing $29.45 paperback. $49.95 sented clearly, with complete and con- hardbound. It's available from Tab Pro- cise MtamatlaW explanations, and numerous exam- fessional Reference Books Inc., P.O. Rodle Stations ples. There is even a glossary terms Box Guido of 40, Blue Ridge Summit, PA 17214; BP155 -INTL RADIO and a complete index. Readers will be Tel. 717/794 -2191. STATIONS GUIDE .... $6.95. New edition lists sta- able to begin using Q & A almost im- tion site. country, frequency. mediately, and will understand every Computer Power Requirements ERP provides for thou- By Mark Waller sands of short wave radio command, function, and module thor- stations. Nine sections oughly, with the expert instruction found In 200 pages, the author presents an cover a variety of broadcast in sery ces. in this comprehensive guide. -depth discussion of power regulation Q & A Simplified contains 368 pages problems and solutions for mini, main- 4 BP105- ANTENNA frame, PROJECTS .... $5.00. for $18.60 paperback from Tab Books and microcomputers. Practical antenna designs Field engineers, technicians, and com- including active. loop. and Inc., P.O. Box 40, Blue Ridge Sum- ferrite types that are simple mit, PA 17214; Tel. 717/795 -2191. puter repair professionals will welcome and inexpensive to build. this thorough reference addressing how yet perform well Also included are antenna ac- The Illustrated Handbook to use the proper electrical power. The cessories. of Desktop Publishing book addresses the issue of power regu- 25 Simple and Typesetting lation not only as it is related to micro- Amateur Band BP125- SIMPLE AMA- Acnals By Michael L. Kleper computers, but minis and mainframes TEUR BAND ANTENNAS - Now, computerized .... $5.00. Shows how to typesetting ex- as well, and how power regulators can build 25 antennas starting pert Michael Kleper has produced more best be implemented to provide "clean with a simple dipole and working on up to beam. tri- than 700 pages of concise, practical, power" for all systems. angle and even a mini and comprehensive analysis and how - rhombic to information that cover the scope of

this innovative technology. l,wn wtrr BP132 SHORT- 4 -25 Writing in a clear, nontechnical style, f lut trKatdnr WAVE BROADCAST AN- 11r4u i rrment s TENNAS. . . . $5.00. Good Kleper gives practical, detailed infor- antennas can be inexpensive. Here's 25 different mation on the mechanics of typesetting ones ranging from a simple and graphic reproduction, important dipole. through helical designs to a multi-band um- trade practices and terminology, and the brella personal computer hardware and software products currently available. He 25 5,,npte Indoor aml Wundur also provides invaluable guidance in lay- BP136 -25 INDOOR enan. AND WINDOW ANTEN- out and design -essential elements in CIRCLE 95 ON FREE INFORMATION CARD NAS .... 55.00. It you can put up a conventional the full realization of desktop publish- antenna because of where ing's huge potential. Topics covered include: utility power, you live. one of these 25 de- inside the signs is likely to solve your building, lightning, static, and problem and deliver great noise, grounding, personal computers reception. and office electronic equipment, tran- sient suppression, isolation and distri-

MAIL TO Electronic Technology Today Inc. bution, voltage regulation, M -G sets, P0. Box 240 rups, and UPS, batteries for UPS sys- Massapequa Park. NY 11762 -0240 tems and PC power. SHIPPING CHARGES IN USA 8 CANADA No. 22561, Computer Electrical $0.01 to $5.00 ... $1.00 $30.01 to 40.00... $4.75 $5.01 to $10.00 ...$1.75 $40.01 to 50.00...$5.75 Power Requirements retails for $19.95 $10.01 to 20.00 $2.75 $50.01 and above $7.00 and is available at bookstores, electron-

$20.01 to 30.00 . $3.75 CIRCLE 98 ON FREE INFORMATION CARD ics distributors or direct from the pub- OUTSIDE USA & CANADA Topics fully covered in this huge book lisher, Multiply Shipping by 2 for sea mail SAMS, 4300 West 62nd Street, Multiply Shipping by 4 for air mail include preparing professional- quality Indianapolis, IN 46268. Tel. 800/428 - Total price of merchandise $ newsletters and reports, using comput- SAMS. Shipping (see chart) $ Subtotal $ erized input workstations for commer- Sales Tax (NYS only) S cial phototypesetting, what to expect Turbo C Programming for the IBM Total Enclosed $ in terms of printing quality, cost sav- By Robert Lafore ings over traditional Name printing methods, This tutorial contains 608 pages of necessary equipment, printing terminol- information, Address examples, exercises, and ogy, sources of further information, up- questions and answers for beginning and Lty State Zip to-date product reviews, including IBM (Continued on page 89)

24 The Electronic Industries Association /Consumer Electronics Group has recently completed the first in a series of videocassette training tapes. EIAICEG ANNOUNCES COMPLETION OF NEW "BASIC CAR AUDIO INSTALLATION" VIDEO TAPE

If you are thinking of "cashing in" on the prof- tion facility, covering basic as well as specialized its in the ever growing car audio service business, tools needed for the installation business. the troubleshooting -service -installation -and This informative videotape is also an excellent removal of car audio products is a large, non -com- aid to the electronics technician in that it gives petitive profit center for your service facility. This the correct procedure for removing and replacing thirty minute video introduces you to the ever "any" car radio from the dashboard of any car increasing complex world of car stereo installa- and shows the installer's, salesperson's and cus- tion. It guides the new installer or owner in the tomer's role in the installation and sale of car correct layout and design of a car stereo installa- audio products.

KEY TOPICS COVERED for installing car audio IN THIS VIDEO equipment. The design and layout of The technical resources a car stereo installa- available for information tion center. about specific types of Basic and specialized vehicles, dashboard dis- tools needed for car audio mantling, speaker sizes and installation work. antenna locations. Safety in the shop. Speaker wiring types How to treat the cus- found in the automobile. tomer's car, from pre- instal- Common and floating lation checkout to demon- ground systems -how strating to the customer to differentiate. Proper the completed job. wiring procedures used The proper procedure in the car.

The cost of the videocassette is $30.00. Use the order form below to order yours now! Send to: EIA /CEG, Department PS, P.O. Box 19100, Washington, D.C. 20036

Basic Car Audio Installation Quantity Amount Ibtal Enclosed Videocassette $30.00 each

VHS BETA [

Name Title Firm Address City State Zip r REMOTE TVRO DISH POSITIONER

Remote- positioning satellite dishes are costly, but you can take an inexpensive immobile unit and convert it By Sam Allen

WHEN I BOUGHT A RING -MOUNT DISH ANTENNA, I an ordin .iy TV antenna rotator. The directions given here are was attracted by the low price, ease of setup. and for a Wilson dish, but most other ring mount dishes are portability. I thought that I could live with the similar. manual positioning. since the programming I wanted was all on one satellite. But once I started watching satellite TV, I Getting Stated found programs all over the Clarke Belt that I wanted to First, disconnect the dish from the ring at the pivot ears. To watch. After a few late night trips out to the dish to move it to do this, remove the upper pin from the elevation strut and the a new satellite, I decided that a remote positioner was a two bolts that attach Vie dish to the ring. necessity. To avoid making modifications to the rotator, I chose to The design I finally came up with uses readily available make the attachment points as much like a standard TV parts and is easy to bolt together. The heart of the positioner is antenna mast as possible You'll need two pieces of I -in. square aluminum tubing about 16 -n. long, see part B in Fig. I (letters refer to part labels on plans.) You can get it from a local shop that repairs RV's and campers. You could also salvage some from an old TV antenna with a square boom. as long as it is heavy-duty enough. Flatten the ends of the square tubing in a vice and bend 90 degrees. Make the bends so that the right angle ends will slip between the ears on the dish or ring. Drill holes in the flat ears on the square tubing. Line up the holes with the holes in the ears on the dish or ring. Now bolt one piece of square tubing to the ring and one to the dish. The tubing should he placed on the dish so that one flat face is resting against the rear of the dish edge.

Clamping the Ro~ator Next cut a piece of I-1/4-in. dia. antenna mast or EMT 6-in. long for use as section C. Attach that piece of mast to the square tubing on the ring. I used a "U" bolt clamp, part E, salvaged from an old TV antenna. You can buy a similar one from Radio Shack ( #15 -826). The one I used has a steel reinforcement to keep the aluminum tubing from crushing as the bolts are tightened. The Radio Shack version lacks that feature, so you may want to add some large washers. Center The dish will rotate like crazy with a rotator tecause the clamp on on section B and drill holes through the square most rotators swing nora than 364 degrees. That is more than tubing for ends of the "U" clamp. Another "U" clamp is enough to cover the fill horizon plus. used on the dish. Attach it to the square tubing in exactly the 26 o PIVOT EARS DISH

FEBRUARY 1987

1" SQUARE TUBING

MAST 1 -1/4" DIA. 19" LONG

"U" BOLT CLAMP Fig. 1 -The leters in this assembles 0 diagram are st.pl'ied or reference purposes only; they dD not indicate the order of assembly Also, they are not used to indicate irdividua parts ROTATOR (note that there are two part B's and two part E's). You should of course 0 attach the least cumbersome parts "U" BOLT CLAMP together first. Imagire trying to mount the dish and rotor assembles onto the ring as a complete u it after MAST 1 -1/4" DIA. 6" LONG putting them together. You may like to try putting the. "U" bclts through 1" SQUARE TUBING their proper holes and attaching their nuts first, sliding the pieces of tubing into positiDn arlterwarc.

RING

PIVOT EARS

same way except that the holes are also drilled through the edge of the dish.

Dish Attachment Another piece of 1-1/4-in. dia. TV- antenna mast D is attached to the dish as section D. On the Wilson dish there is a bolt hole about 14 -in. from the edge that is used for a brace on the feedhorn arm. The mast should be about 19 -in. long so that it will reach that hole and still have 5 -in. protruding from the edge of the dish to attach the rotator. Flatten the end of the mast and drill a hole so that it can be bolted to the dish with the feedhorn arm brace bolt. Next make a slight bend in the mast at a point about 8 -in. from the other end. The bend should be about 30 degrees. To check the angle, temporarily bolt it in place on the dish Attaching the TV antenna rotator to tie. dish is simplified with the "U" clamp. Place a long straight board across the by using a standard TV- antenna mast and clamps. front edge of the dish at the top and bottom. The end of the mast that extends past the edge of the dish should be parallel not long enough. you can huy a longer one at any local with that board; if it's not. remove the mast and adjust the hardware store. bend. When the angle is correct, bolt the mast permanently to the dish. The ends of the "U" clamp should extend through to Using Bearings the front of the dish. That will clamp the square tubing and A bearing at the top of the dish where it attaches to the mast tightly to the dish. If the bolt supplied with the clamp is elevation strut (see Fig. 2) is needed for the dish to rotate. A 27 PLASTIC BOX

O5O0KS2 DISH POT

O CABLE CLAMP

HANDY v..fiG BOX MOUNTING EARS Fig. 2 -This view of the caster assembly is what you would see if you sat on the ground near the ring to look up at the elevation strut. The cable clamp should be positioned to allow easy access to its adjustment screws. You will tighten them only after the dishes extreme position has been reached in order to calibrate the 500K BOX COVER potentiometer (J). If the caster mount is too large for a comfortable fit on the elevation strut, try padding the OSTEEL space by placing washers on both sides STRAPS of the strut. Do the same if there is any space between the handybox and mounting ears. The steel strap for the OCASTER microswitch can be bent afterward to (WHEEL REMOVED) position the cutoff switch.

OMICRO SWITCH ELEVATION STRUT

ball -bearing furniture caster (denoted part F) is used for that purpose. The bearing is important to the operation of the system, so don't skimp here; buy a quality caster with a ball bearing swivel. Also look for one that has a nut on the wheel axle. The wheel is not used, so it's easier to remove it if the axle can be unscrewed. Remove the wheel and bolt the caster to the bottom of an electrical outlet box, part G. Get the type known as a handy box; it is about 2 -in. wide x 4 -in. high x I- 3/4 -in. deep; it doesn't have any cable clamps, and it has a knockout in the maph. center of each end. About half way up the sides of the box figt drill Vi-in. dia. holes that will line up with the holes in the !t? ears on the top of the dish. Be sure to drill the holes in a solid section of the box, not one of the knockouts. The rotator clamps to a short piece of 1- 1/4-in. Box Attachment diameter mast. The mast is attached to a piece of sgL.are tubing with a "U" clamp. The ends of the square tubing are Place the box over the ears with the caster and facing down flattened and beat to fit between the ears on the ring attach it with bolts. If the box is wider than the spacing of the mount. ears, use washers to fill the space between the inside of the box and the mounting ear. Use the same number of washers Rotator /Dish Alignment on each side so that the box will be centered. Use a separate Loosen the rotator clamps on the dish mast slightly so that bolt for each side. You can reach inside the box with an open - the dish can be turned by hand. Move the dish to the extreme end wrench to tighten the bolt. east and west positions while watching the caster to make Clamp the rotator, A, to the small section of mast, C, on sure that the bearing is opperating correctly and nothing the ring. Put the mast, D, attached to the dish into the top of interferes with the movement of the dish. While the clamps the rotator and temporarily tighten the clamps. The elevation are still loose on the dish mast, use the control to rotate the strut fits into the caster, F, in place of the wheel. Attach it by rotor to the extreme west position. running a bolt through the axle holes in the caster and through Hold the dish to keep it from turning too far. Now rotate the the hole in the top of the strut. dish to the extreme west position and tighten the clamps.

28 limit, that isn't a big problem. A more elegant solution might be to run another conductor to the control switch to allow you to reverse the dish after it has reached the limit.

Satellite Position Originally I planned to use the indicator on the rotator control to locate the satellites, but I found that it just wasn't accurate enough. I solved that problem by adding a 500K- ohm potentiometer, J. to the upper -bearing assembly on the dish to sense the dish position. Use a potentiometer with a long shaft and mount it in a plastic weatherproof box (K). A piece of steel strap, I, about I0 -in. long is used to hold the it stationary. You can buy steel strap with pre- punched holes at most hardware stores. Drill a hole in the end of the strap or use a pre- punched hole and place it on the potentiometer shaft before the nut, Another piece of square tubing is bent to fit put the nut on the potentiometer and tighten it. Remove between the ears on the dish. A 19' long section of mast is then attached to the square tubing with a "U" bolt clamp. The the top knockout in the handy box. Install cable clamp H in mast is bent :o about 30 degrees 5" up from the end. the hole. Put the shaft of the pot in the clamp, but leave the clamp loose for now. Bend the steel strap until it can be Cutoff Switch attached to the elevation strut. Use sheet metal screws to I started using the system at this point, but as I used it, I attach it. You can even use the same screws that attach the found that it needed further refinement. The rotator is de- limit switch. signed to turn a full 360 degrees; however, the dish would be ruined if it rotated that much. To stop the rotator, install a 500KS2P0T IN HANDY BOX limit switch made from a microswitch (part L) mounted on a PLASTIC BOX steel strap (section I). Solder wires to the common and NC BALL BEARING CASTER terminals. Attach the switch to the strap with small machine screws. Weatherproof the switch with heat -shrink tubing, east tape or silicon chalk. Rotate the dish to the extreme LIMIT position and place the strap on the elevation strut so that the SWITCH switch touches the back of the dish. Drill holes in the strut DISH and attach the strap with sheet metal screws. The strap can be bent to make minor adjustments of the limit switch position. I wired the switch in series with one of the wires to the rotator; the only problem with this simple solution is that it disables the rotator until you manually move the dish awa from the switch. Since I rarely run the dish all the way to tht.

PARTS LIST FOR THE REMOTE POSITIONER A -TV antenna rotator (Radio Shack #15 -1225) B -1 -in. square aluminum tubing, two pieces 16-in. long C-1 -'/4-in. Dia. steel mast, 6-in. long. (Radio Shack ROTATOR #15-842) D-1 -1/4-in. Dia. steel mast, 19-in. long. (Radio Shack RING, #15-842) E-"U" bolt clamp, two required. (Radio Shack #15-826) F- Furniture caster with ball bearing swivel G -Electrical outlet box, (Handy Box) H- Cab!e clamp for Handy Box I -Steel strap, two required, one 10 -in. long, one 2- in. long J-500K -ohm potentiometer ( -Plastic box (Radio Shack #270 -220) L- Microswitch SPDT, lever type with roller (Radio Shack #275-017) Fig. 3-After assembly, the positioning fun begins. The ADDITIONAL PARTS AND MATERIALS first thing you'll need to adjust is the elevation. Try to get it back to the angle it was originally in. 6- Hex -head bolts 1 -in. long.'/4 -In. Dia., 20 nuts and lock washers 2- pan -head, sheet metal screws Y2 -in. long #8 type; 2 round -head machine screws 1 -in. long with 2 -56 Adusting the Pot nuts; Cable for rotator and position indicator: OHM Attach an ohmmeter to the potentiometer and adjust the pot meter tape, heat -shrink tubing, silicon caulk, wire, etc. until it. reads zero; that is usually slightly before the shaft

29 This interior view of the controller shows how the DPDT switch was added. The light colored round assembly on tie right is the original control switch.

The upper bearing assembly is made from an electrical needed to position a satellite dish. I added a spring octlet box and a furniture caster with the wheel removed. return, the box shown here uses internal cable clamps. bu center off DPDT switch and found that I could better control e4erience showed that a "-fandy Box" with knockouts fcr an the movement better. external clamp would make installing the position sensing The dish is set up almost the same way it was before pct easier. The plastic box at the top of the assemb y modification. Before starting to aim the dish, use the control hcuses the pot. The shaft is Inserted in a cable clamp 3n to position it in the Handy Box. and the perforates steel strap holds the pot the center so that it lines up with the ring as it stationary while the dish rotates_ did originally. Instead of aiming at a particular satellite, aim the dish due south. Adjust the elevation to the proper angle for your latitude. A local dealer can tell you that angle. The angle mark on the dish may be a little off after the modification, so if you can, find out how much correction the scale needs. Initial setup will be easiest if you can see the TV from the dish. Put the TV in a window or bring it outside. Put the receiver on scan and move the rotator control until you see indications of a signal, then switch off the scan and tune in the transponder. Jog the control back and forth slightly until you get the best signal, then readjust the elevation angle for strongest signal. Now use the control to move the dish to other satellites. If you can get a few satellites that are close to the first one but not the ones farther away, the dish probably isn't aligned due south. Rotate the ring a small amount and try again. If you get even fewer satellites, rotate the ring in the opposite direction. Once you are getting a signal from most of the satellites, you can fine tune the position. Use the control to rotate the dish to Satcom F3R. Adjust the elevation until you get the best signal. Next position the A m croswitch is used as an eastern- direction limit switch. dish on Satcom F4, readjust the When the dish reaches the extreme east positior the switch elevation angle; note the old open the rotator switch. The bu It -in limit of the rotator angle and the new angle. Now set the elevation half way is ised for the extreme west. between the two previous angles. Turn the ring about 1/4-in. to get the best signal. Next move the dish back to Satcom F3R. stops. Setting the pot with the ohmmeter will enable you to Make a note of the present elevation, then adjust to see if the read the dish position from the beginning of the arc without a signal can be improved. If the signal was already at its dead spot. Rotate the dish to the extreme west position. Now strongest, leave the dish at that setting. If you had to readjust tighten the cable clamp onto the shaft of the pot. As the dish the angle, then return to Satcom F4 and repeat the process rotates, the pot should remain stationary and the shaft rotates until you are satisfied with the adjustment. With the dish with the dish. properly positioned, you should be able to find all of the Run a two-conductor cable from the pot into the house. satellites from horizon to horizon. It may take awhile to get The simplest way to read the dish position is to connect the the dish positioned correctly the first time, but once you have leads from the pot to an ohmmeter. Make a note of the ohm the technique figured out, it's not too hard to set it up in reading for each satellite. Turn off the meter after the dish is several other locations. positioned to save on batteries. Of course you could design a If you will be using the dish in the same location repeat- lot more sophisticated readout if you like. It could be a digital edly, you can place stakes in the ground to line up with marks display or a meter with the satellite positions simply marked on the ring. That way you can be set up in a few minutes. on the face. You will be able to enjoy many hours in front of the family tube pulling in those long range signals. A few seconds The Controller adjusting the rotator is all it takes. Enjoy your hobby and The controller I used wasn't designed for the fine control happy planetary viewing.

30 BUILD A MAXWELL INDUCTANCE BRIDGE Those inductors of yours need never mystify you again. With this project you can know their exact value.

By C Hall

are DHERE IS A SIMI'I.I., INEXPENSIVE INSTRUMENT YOU CAN become equal when the components of the bridge ad- build to measure those unmarked RF chokes, torroids, audio justed so their values satisfy the following two equations: practically chokes, and power-supply filter chokes that are LD = RARCCB given away at electronics flea markets. It reads values directly, without mathematical calculations, from 500 micro- To calculate the "Q" calibration points for RB you can use henries to 90 henries. To make it work you'll need a 1,000 the following equation: Hertz sinewave oscillator to energize the bridge, and a pair of Q = wCeRe the null that occurs when the bridge headphones to listen for However, no calculations are necessary to determine LD you haven't got a 1 kHz oscillator, don't worry is balanced. If and Q if we chose our parts wisely. there are plans for one following. How it Works Electrical Theory ligure I shows a schematic of the basic Maxwell bridge as voltage dividers, each The bridge may be thought of two circuit. The LE/RD leg of the bridge is the unknown inductor oscillator, with the headphones being connected across the being measured, and its internal DC resistance. Resistors RA the outputs of the voltage dividers connected between two and R(. are variable and calibrated directly in inductance; RA 1). voltage divider is made up of RA, RB, and (see Fig. One is varied in steps by a range switch, and Rc is a calibrated consists of Rc, RD, and LD. In CB; the other voltage divider potentiometer. Resistor RB is variable and can be calibrated the headphones, the voltage and order for a null to occur in directly in values of Q (quality factor), provided the oscillator voltage divider must be phase angle at the output of one frequency remains fixed at some specified value. and phase angle at the output of exactly equal to the voltage When the unknown inductor is connected to the bridge as voltages and phase angles the other voltage divider. Those shown, RA, RB, and Rc are adjusted until the audio oscillator's tone in the headphones dips to a null and cannot be heard. The bridge is then said to be balanced. The inductance value is read from the dials of RA and Rc, and the Q of the inductor is read from the dial of RB. From the previous equations, we see that balancing the bridge is independent of frequency, so the exact frequency of the audio oscillator is of no particular concern, except that it AUDIO has to be in the audible range of the ear so you can hear it in OSCILLATOR the headphones, but you have to know what the frequency is if you want to calibrate RB with values of Q. The value of CB is selected to be compatible with the resistance values of the bridge and the range of inductance to be measured, according to the equations for balance. The exact value of CB affects the accuracy of the bridge, so you don't want to use a 0.1 -µF capacitor that has a -20 to + 80% tolerance, or guaranteed minimum value (GMV) tolerance. Try to get a capacitor having a tolerance of ±.10% or less. Fig.1 -The maxwell bridge has been around for a long long For more information on bridges, see Electronics Mea- time, but it's more than adequate for inexpensive inductance measurements. Its accuracy is up there too. surements, by F.E. Terman and J.M. Pettit, pages 69-73. 31 PARTS LIST FOR THE INDUCTANCE BRIDGE Resistors (All fixed resistors are 1/4-watt, 1% precision metal -film units.) R1 -10 -ohm R2- 100 -ohm R3 -1000 -ohm R4- 10,000 -ohm R5- 100,000 -ohm R6- 500,000 -ohm potentiometer (audio taper preferred) R7- 10.000 -ohm potentiometer. linear taper The binding posts in the upper left -hand corner of the ADDITIONAL PARTS AND MATERIALS Inductance Bridge are used to connect the inductor under 5 -WVDC. capacitor, with 10% or better test to the circuit. You can use simple alligator clips to tolerance test inductors in circuits as long as you take their accompanying components into account. J1 -Phono jack J2 -Phone jack J3, J4 -5 -way binding posts S1- Rotary switch, 1 pole, 12 position (Radio Shack 275 -1385) Plastic box enclosure 6 3-3/16x 1-7/e inches, knob for switch, dials (2 required).

oscillator waveform is a fairly good sinewave. The amplitude of the sinewave should be on the order of five to ten volts peak -to -peak. Jack J2 is the phone jack for the headphones, which may be either high- or low- impedance type. Jacks J3 and J4 are 5 -way binding posts to which the inductor to be measured is connected. The I% resistors are available from Radio Shack in a kit of 50 resistors. Resistor R7 is a 10,000-ohm linear-taper potentiometer. Resistor R6 should be a 500,000 -ohm audio -taper potentiometer; linear taper will work, but it's not as easy to adjust at low Q values. All the components for the bridge can fit onto the back If you can't get a 500K unit, use a I MEG, not a lower value; cover Note that all the switch positions for S1 are not used. You may fill them with other resistors to extend the if R6 is too low, you can't get a null with high -Q inductors. units range or to place capacitors in parallel with C1. Capacitor CI should be as near to 0. I -µF as possible. Ideally, if you have access to a commercial digital capacitance meter, you should select a capacitor whose value is within I% of 0.1 -RF. I settled for one that was marked for 5% tolerance. R7 All the parts are mounted in a Radio Shack plastic case 10K measuring 6 x 3 -3/6 x 1-7/ii inches. the dials, which are cali- J1 LINEAR PHONES 1000 Hz CCW brated for L and Q, am from available WW II surplus military OSCILLATOR J2 equipment. INPUT Calibration

J30 -' Lo Calibration of the L and Q dials is with an ohmmeter; a s digital type give INDUCTOR will the most accurate calibration, but an

UNDER analog type may be used. Table 1 shows the calibration < i TEST

J4 Q Table 1- RESISTOR CALIBRATION VALUES

RB R

OHMS O OHMS L OHMS L Fig. 2 -This ingenious little device doesn't need a power 0 0 500 .5 7000 7 supply, only a 1kHz sinewave source. The toughest parts to 1.6K 1 1000 1 8000 8 get are the precision resistors, available all over. 4.8K 3 2000 2 9000 9 16K 10 3000 3 9500 9.5 Selecting the Parts 48K 30 4000 4 160K 100 5000 5 Figure 2 is a schematic of my version of the Maxwell 320K 200 6000 6 bridge. Resistors RB and Rc are denoted as R6 and R7 respectively. Capacitor CB is marked as CI, and SI (the range marking required On the dials versus thl resistance setting of switch) allows you to select different values of RA from RI the pot for each marking. Connect the ohmmeter across the through R5. pot, adjust the pot until the ohmmeter reads the desired value, RCA phono jack, JI, receives the output of a 1000 Hz then mark the pot's dial according to Table I. Mark the sinewave oscillator. You can't get a good null unless the (Continued on page 94) 32 76 a^ ,qe ;y , 5 Me, , W ' , I M 1 9 5 ) 1 T) ],1STT ) ,T` 29 30 0 f ` 96 , 0 I7O 70 9 1 76 7Ó ne'1 `1 ' g 1 W * 1 6 t! 79 5 1 . ,OS' . _ ,` ,' x ÿ Didra lçl0Nrthàji, 1YV^ , ó Armist'.y f T ° Mdjdq 30 I 15 and' eVérfi, 12 `tWfëtlééñT Iasahstadlyl 4th thirweät4W°" 0 1 ,3 T S ]2 191 9 w y . S 'b) I ), ,:,;',;',2,,n::;$'2529 S 6 )0 _. ... , f 5. _ ,. `S :6 1:e T9 ,911 ,q TO 5 , 5 9` 1 ,1 , T l f 1, Decem-- W T ) S I1S w , W 1 6 1 S 6 S,6 I w s e 7 ,911 5 , f 5 . 6 '. ,S T ; $y'.lamès Tärt;hinskt

very IT ALL STARTED, AS MANY COMPUTER PROGRAMS D(), has the BASIC language. Memory requirements are with a simple question. In this case the question, which came small so this software does not offer any problems. from a trivia game, was: On what day of the week was the There is only one restriction on the dates that this program Declaration of Independence signed? If there were a comput- can deal with (remember, I said almost never): they must fall a very, very, er handy at the time I might have gotten it right. With DATE - in or after the year 1590 A.D. Unless you have CAL.BAS I'll never again get that type of question wrong. very old grand aunt, the software shouldn't cause you any Well, almost never. headaches. DATE -CAL.BAS (which is short for Date Calculations) is a BASIC program that performs two types of calculations. Operation it First, you can use it to determine the number of days between Table 1 is a printout of DATE -CAL.BAS. Type into your any two dates. The second feature allows you to determine the computer and save it to disk by executing the save command: day of the week that any given date has fallen on or will fall After typing RUN to start executing the program, you on. should see the main menu appear. Here you can select which type of calculation you would like to perform. By keying I, Programming Considerations you can obtain the days between two dates; or by keying 2, Although the program is designed for the IBM PC series of the day of the week for a given date. computers, it is easily modifiable to run on any machine that If you select the first option, number of days between

Table 1 -Date Calculation

100 DATE CALCULATIONS 450 PRINT : PRINT 460 PRINT "THERE ARE " ;V2 - V1 ;" DAYS BETWEEN THESE ": 110 ' BY JAMES E. TARCHINSKI PRINT "TWO DATES. ( " ;(V21- VI) / 365.25" YEARS.)" 120 ' 130 FOR I = I TO 7 READ DS(I) NEXT 470 PRINT : PRINT PRINT 140 DATA SUNDAY, MONDAY ,TUESDAY,WEDNESDAY,THURSDAY, 480 PRINT "PRESS ANY KEY... "; = FRIDAY, SATURDAY 481 AS= INKEY$ : IF A$ "" THEN 481 490 GOTO 160 150 '

7 : 500 160 WIDTH 80 : KEY OFF : COLOR CLS 170 COLOR 6 PRINT "DATE CALCULATIONS PROGRAM" : COLOR 7 510 ' 520 ' * ** INPUT DATE 180 PRINT : PRINT 190 PRINT "WOULD YOU LIRE TO CALCULATE... PRINT 530 ' 200 PRINT "1) NUMBER OF DAYS BETWEEN TWO DATES ": 540 CLS 7 PRINT 550 COLOR 6 : PRINT QS: COLOR 210 PRINT "2) THE DAY OF THE WEEK FOR A GIVEN ": 560 PPINT PRINT "USE THE FORM: PRINT " DATE ": PRINT 570 "DATE: " ;M,D.Y 220 PRINT YOUR CHOICE ('RETURN' TO EXIT): "; 580 INPUT FLAG = 0: PRINT 230 INPUT 590 600 IF M < 0 OR M , 12 OR D < 0 THEN FLAG = 1 240 IF AS = "" THEN CLS : END (7):: 610 IF (M = 4 OR M = 6 OR M = 9 OR M = 11) AND 250 IF AS < "1" OR AS ' "2" THEN PRINT CHRS GOTO 230 D . 30 THEN FLAG = 1 620 IF (M = I OR M = 3 OP M = 5 OR M = 7 OR 260 IF AS = "1" THEN GOTO 390 M = 8 OR M = 10 OR M = 121 AND D ' 31 THEN FLAG = 1 270 630 IF M = 2 AND D , 29 THEN FLAG = 1 280 ' * ** DAY CALCULATION * ** 640 IF FLAG < I 0 THEN PRINT "INVALED MONTH /DAY 290 QS = "PLEASE ENTER THE DATE:" 560 300 GOSUB 520 SPECIFICATION. ": GOTO 650 IF M = 2 AND D = 29 AND Y < , 4 * INT (Y 310 DW - V - 7 * ( INT (V / 7)) THEN PRINT Y ;" IS NOT A LE 320 IF DW = 0 THEN DW = 7 AP YEAR! ": GOTO 560 330 PRINT : PRINT 660 IF Y < 1590 THEN PRINT "ALL DATES MUST BE 340 PRINT "THIS DATE IS ON A: " ;DS(DW) ; "." 350 LOCATE 22: PRINT "PRESS ANY KEY... "; AFTER THE YEAR 1590. ": GOTO 560

351 670 ' 351 A$ =INKEYS : IF AS = "" THEN 360 GOTO 160 680 ' CALCULATE 'V' 370 690 ' 380 700 IF M , 2 THEN GOTO 730 V = * Y D 31 * (M - 1) INT 390 ' * ** NUMBER OF DAYS * ** 710 365

400 ((Y - 1) / 4) - INT (.75 * I INT (tY - l, " 410 QS = "PLEASE ENTER THE FIRST DATE: 720 GOTO 740 420 GOSUB 520:01 = V 730 V = 365 * Y D 31 * (M - 11 - INT

" , INT (Y 503) 1!, 430 Qs = "PLEASE ENTER THE SECOND DATE: (.4 M 2.3) INT (Y / 4) - INT :.75 440 GOSUB 520:02 = V 740 RETURN

33 TABLE 1- EXPLANATION OF THE BASIC PROGRAM

Line No. Function(s) 100-150 Initialize the program 160-270 Main Menu -select program option, either (1) days between dates, or (2) day -of- the -week calculations 280-380 Perform selection (2), day -of- the -week calculations 390-510 Perform selection (1), days between dates calculations 520-740 Subroutine to enter date and calculate 'V', the number of days from a given reference date 550 -560 Print screen title 570 -580 Enter date 590-640 Check entered date to make certain it is valid, if not (i.e. if FLAG -1), an error message is printed on line #640 650 Check for leap -year 660 Check to be certain that the date entered is after A.D. 1590 (this program is not valid before 1590). 670 -740 Calculates 'V', the number of days between the entered date and a given reference date.

dates, the software will prompt you to enter two dates. Be pled" Moon landing and the day when astronauts from Ap- sure to enter them with the earliest date first, or the program ollo II actually set down on the Sea of Tranquility. will produce a negative answer. Also, be sure to enter them in If you select the second option (2) of the main menu, the the format shown on the screen: day of the week for a given date, the program will prompt you MM,DD,YYYY to enter a date. After doing this, the computer will then 06,27,1929 produce the answer on the screen. As a check, you may want If you don't enter the dates correctly, the screen will either to enter December 7, 1941 (12,7,1941) which, of course, fell direct you to do it again (correctly), or the program may on a Sunday. crash. Table 2 offers a group breakdown of the BASIC program's To check this part of the program enter the dates May 26, logical steps. Refer to it should you have troubles after input- 1961 (5,26,1961) and July 20, 1969 (7,20,1969). The comput- ting. er should return an answer of 2977 days. That is the length of Incidentally, for those of you who play trivia games, July time between President Kennedy's speech calling fora "peo- 4, 1776, fell on a Thursday.

MACHINE TALK By Walt Philips

..ta, "I don't know about you, but I'm AL ready for a hot -lube recess." "It replaced ten men, but it took twenty technicians to install it." iteggi

"It started out as a pocket calculator, and then it sort of got out of hand." "It's amazing what we can do with one arm."

34 POWER PLAY

Once you've put this power supply on your workbench, you'll need no other!

By Sidney E. Buck

['ANYONE WHO IS INTO ELECTRONICS, WHETHER FOR FUN have a "universal" power supply, you still have to hook up an or for profit, is sure to have several low- current power sup- ammeter to monitor current, which means breaking the cir- plies, outputting various voltages, lying around the test cuit to keep track of the load current. And things are further bench. How many small bench power- supplies do you have? complicated if, like most other hobbyists. you only have one (I have five, only one of which outputs up to I ampere of meter -a multimeter (either digital or analog: it really current.) doesn't matter). To simplify the bench setup, a digital display Having grown weary of switching power supplies each was incorporated into the Power Play, enabling you to check time that a different voltage or current level was needed, I voltage and current (without breaking the circuit) levels. decided to put together a supply that could output from zero to around twenty-five volts and provide up to one ampere of Keep it Simple current, plus supply a sprit: of negative voltage whenever The Power Play is a rather simple circuit built around needed. commonly available components, as revealed by the sche- What's that...you say already have a power supply that can matic diagram shown in Fig. I. The heart of the circuit is the handle all of your power-supply needs? Big deal! Even if you power-supply section (precisely two power supplies). based on ordinary 3- terminal regulators -two 7805 5 -volt regulators and an LM3I7 positive adjustable regulator. Two of the regulators (UI and U2) supply outboard power for testing and experimenting. The LM317 adjustable regulator is continually variable from 1.2 to 30 volts (as measured between 0 -30V and GND), meaning that it is necessary to provide a little squirt of negative voltage to force the adjustable output to the zero level. That's accomplished by feeding the output of U2 through D3 and D4, for a two -diode voltage drop (about 1.4 V), which, when fed through D2 to the output of UI, cancels out the regulators "idling" voltage. The other half of the outboard power -testing power supply (U2) has its positive output connected as ground. with what would normally he the ground return line used as the negative -voltage output. In other words, U2's output is used as a positive ground. and the negative output of BR2 fed through as a negative voltage. The level between the positive (GND) and the -5 / -IO terminals is clamped to 5 -volt (without respect to the regulator's configuration). printed The author chose to assemble the circuit on -circuit The third regulator (U3) provides power tier the display board. But, since this is suppose to be a junkbox circuit, power supply (consisting of U3, a use whatever material (PC board or perfboard (either the elements. The display's plain Jane, or copper -clad type) -you have on hand. 7805, 5 -volt regulator fed from a .5 -A bridge rectifier) is nothing more than your basic 3- terminal regulator circuit. Its single -pole, double -throw switches which would otherwise regulated output is filtered by CIO (a 2200 -µF capacitor) and have to be set individually, each section doing a different job. fed to U4 (a CA3I62E AD converter), U5 (a CA316IE 7- segment decoder /driver) and finally, the display units, Putting It Together DISPI -DISP3. The author chose to assemble the circuit on printed- circuit The output of UI, sampled across R3 (a I -ohm resistor), is board. But, since this is suppose to be a junkbox circuit, use fed to the input of the A/D converter U4 at pins 10 and 11. The whatever material -PC board or perfboard (either the plain voltage across a 1 -ohm resistor is a direct measure of the Jane. or copper-clad pre- etched type) -you have on hand. current through the device. SI, a 4 -pole, double -throw And so, no etching pattern is shown because of the certainty switch, is used to alternate the meter readings between volt- that your parts are of different shapes and sizes- besides, age and current. If a four-pole, double -throw switch bothers designing a power supply means doing it yourself. That's you, just consider that the alternative is using four separate where the fun is!

117VAC F1 S3I N p .5A D1 BR' 1N4002 1.5A R3 in U1 LM317T O 0.30V Ti. D2 G R1 1 N4002 22052 Cl C2 C4 2200 ^ 1

` C3 P.2 T10 .."* 5K

O GNO BR2 03 04 .5A 1N4002 1N4002 U2 7805

G T2' R4 (p 12V S2 o C5 + C6 3300 tono ---o P - T1

D5 12V 4115.1V ZENER O 5/ 10V

B 7 5A

U3 7805

r. C7 010

500 1

+ CB 33 SR5 Stour 14 12 16 DISP2 DISP3

113 O O Q si S1-B S1 A 3 b R6 f R1 4 lt 1K 50K U4 2 10 I U5 d CA3162E MSD 11 CA3161E NSD LSD C9 4- 9 e 10 1'. 2 15

10 16 R 14 10K 13 7 6 I LHDP (25 O Q VN S1-D J R9 3300

Fig. 1 -Power Play is a rather simple circuit wilt around commonly available components. At its heart is the power - supply section (actually two power supplies), cased on ordinary 3- terminal regulators -two 78C5 5 -volt regulators and a LM317 positive adjustable regulator. Two of the regulators (U1 and U2) supply outboard power for testing and experimenting. The third regulator (U3) provides power for the system's display elements.

36 Low Power Monostable a ds 61 IIKS-, FactCard 4047: Astable Multivibrator

APPLICATIONS Frequency discriminators Timing circuits Here are Time -delay applications Envelope detection Frequency multiplication your free Frequency division

ABSOLUTE MAXIMUM RATINGS -0.5 to +18VDc FactCards! VDD DC Supply Voltage -I I r,l ml rl VIN Input Voltage - 0.5 to V00 + 0.5Vpç Ts Storage Temperature Range - 65 to +150°G FEATURES Po Package Dissipation 500 mW Introducing Hands -On- Wide supply voltage range 3.0V to 15V T1 Lead Temperature (Soldering, 10 seconds) 260°C 0.45VDD (typ.) A High noise immunity Electronics FactCards. Low power TTL fan out of 2 driving 74L Each issue, Hands -On- compatibility or 1 driving 74LS SPECIAL FEATURES RECOMMENDED OPERATING CONDITIONS will 3 3 to 15VDc Electronics" present Low power consumption: special CMOS oscillator config- VDD DC Supply Voltage new FactCards, each deal- uration VIN Input Voltage 0 to VDDVDc Monostable (one -shot) or astable (free-running) opera- T Operating Temperature Range ing with one of a variety of tion CD4047BM - 55 °C to + 125°C electronics topics. Some True and complemented buffered outputs CD4047BC - 40 °C to + 85 °C Only one external R and C required will deal with electronics basics, some will deal with discrete components, some 4051 will deal with IC's, and 62 Ili]ttcnge FactCard 4052 Analog Multiplexer Demultiplexer some will deal with circuits 4530

I and 1 1 9 applications. 1 11 1 10 1 12 111 116 15 14 13 12 16 115 114 113 11 All will contain the type of A 8 C information electronics hob- 1N/OUT CD4051BM IN- CD40538M byists need, but sometimes IN/OUT IN/OUT IN/OUT Vn' OUT/IN Vy must search to find. With by bx cy c cx 4 OUT /IN 7 INH VEE IN

FactCards, you can find that 6 18 I1 12 13 14 15 16 17 18 11 12 13 14 15 16 17 information in a hurry. 116 115 114 113 112 111 110 19

OD ABSOLUTE MAXIMUM RATINGS OUT /IN VDD DC Supply Voltage - 0.5Vdc to + 18Vdc IN /OUT IN /OUT CD4052BM,. Input Voltage - 0.5Vdc to VDD + 0.5Vdc IN /OUT IN /OUTJ VIN OUT /IN Ts Storage Temperature Range - 65° to + 150°C - V V Po Package Dissipation 500mW OY-. .6.::.,....3.1..-.-; .Y.- IIL . .E T1 Lead Temperature (soldering, 10 seconds) 260 °C 1 12 13 ,14 15 T6 7 8 Clip your FEATURES CONDITIONS Wide range of diggital and analog signal levels: digital RECOMMENDED OPERATING 3.15V, analog to 15Vp. VDD DC Supply Voltage + 5Vdc to +15Vdc Vdc Low "ON" resistance: 80f I (typ.) over entire 15Vp.p signal - VIN Input Voltage OV to VDD Range cards, input range for VDÓ VEE =15V TA Operating Temperature High "OFF" resistance: channel leakage of .10 pA (typ.) 4051 BM/4052BM/4053BM - 55°C to + 125 °C - 40°C to + 85°C save them, at VDD- VEE =10V 4051BC/4052BC/4053BC and start A/D Converter 63 EasicatiK°r FactCard ICL7126.31/2-Digit FEATURES 1 40 building +V 0 2 39 Guaranteed zero reading for 0 Volts input on all scales D1 OS 38 True polarity at zero for precise null detection 3 OSC3 Ci 37 1 A typical input current your 4 al TEST True differential input and reference 5 36 components re- Al (UNITS) REF Direct LCD display drive -no external 6 35 quired. F1 REF 34 Pin compatible with the ICL7106 FactCards G1 +C REF Low noise -less than 150,V p -p 8 33 El -C REF On -chip clock and reference 9 32 Low power dissipation guaranteed less than 1mW 02 COMMON 10 ICL7126 31 No additional active circuits required library C2 IN HI Evaluation Kit available (ICL7126EV /KIT) 11 30 82 IN LO 8,000 hours typical 9 Volt battery life (TENS) 29 2 A2 A/Z ABSOLUTE MAXIMUM RATINGS 13 28 today! F2 BUFF 14 27 Supply Voltage (V' to V 15V E2 INT 15 26 Analog Input Voltage (either input) (Note 1) .... V to V - D3 -V Reference Input Voltage (either input) V to V 16 25 83 G2 (TEN'S) Clock Input TEST to V 17 11005) 24 F3 C3 Power Dissipation 18 23 Ceramic Package 1000mW E3 (100'S) A3 800mW 19 22 Plastic Package AM (1000) G3 Operating Temperature 0 °C to + 70 °C El¢Ctrlonlcsn 20 21 to + 160 °C POL (MINUS) BP Storage Temperature - 65 °C Lead Temperature (Soldering. 60 sec) 300 °C Power Low Monostable 4:2=3^ FactCard 4047' Astable Multivibrator

STMC ELECTRICAL CHARACTERISTCS For new CONDITIONS A A Tit iffr UNITS ideas in ISTIC (11)9.) : ISTIC Vo 'r p (Typ.) () A Vll (V) YI (V) Quiescent Device - 0,5 5 0 02 but Volta( e: - 0.5 5 0 electronics 10 Current. - 0.10 0.02 iï Low-Level - C.1C ! 10 0 Ice 4:ax. - 3,15 15 0.02 Vo, Mac - C.15 15 0 - 3,20 20 0.04 uut Voltáe _ 0,5 5 5 V read Output Low 0.4 0.5 5 1 3.10 10 10 t= H gh-Leve. (Sink) Curren' 0.5 3,10' 10 2.6 3,15 15 15 VD..., Min. - . Nin 1 5 3,15 15 6.8 Radio- Inpit Low 0.5,4.5 - 5 - 4.6 0,5 5 - 1 mA P CVcltag.. Voltags, 1,9 - 10 - 25 0,5 5 -3.2 L.el, V,i Max :.5 13.5 - 15 - Electronics 9.5 3,10 10 -26 a Max rInpU HO 0.5,4.5 - 5 - 13.5 3,15 15 6.8 Voltaga. 1,9 - 10 krrent - V,f, Min. .5 13.5 15 ),18 18 105 - - During t « - -.:e.` the next 12 4051 -a dsón 4052: Analog Multiplexere months 62 FactCard Demultiplexer 4530 Radio -Electronics" ELECTFICAL CHARACTERISTICS will carry up -to -the :L_ ' CON S UNITS minute articles on: CHARAC- hobby computers Units . TERISTIC " i 25Ct - solid -state technology (TYP.) Iiilliiiiillill 11111 TV games Video Quiescent Device 5 0 04 .Ct-annel color TV stereo Current. sup 10 0 04 -: age Curran: test equipment 1,-A Max_ 15 0 04 radio 0 0 10 -001 radar detectors 20 0 08 0 0 15 _001 industrial electronics ON Resistance 0 0 20 -001 nA servicing O>= V Vo- Channels 0 0 10 - 0.01 TV- radio- stereo 0 0 5 470 - experimenter (Common 0 0 15 - 0.01 Ro., Max . 0 0 10 180 it - circuits IN) Max. 0 0 20 - 0.01 exceptional 0 0 15 125 - t C,. construction 0 ON Resistance :11340F..1 30 projects o 0 5 10

N Ror+ 0 0 10 10 il ."..','D40.2 'B Don't take a CD4Ci°3 chance on missing even one issue. Subscribe now and save!

a ds sn ICL7126 . 31/2-Digit /VD Converter ladle c iw FactCard Electronics ELECTRICAL- CHARACTERISTICS Cattlñèt» `1Sip ' Dnlb CtiracMY4Jcs Conditions TIP Unlb Input V. =0 OV - 000.0 Dignal Wading 2av Raading Vti 0 C.2 n9 RH Sade = Oft 3 C- -A<70°C 2COOmV Scale Facto- Vir, = 99.0mV 1 VW =VREF 999,'000 Digital Ftöadrrtg 7C<-<70'C VME= =100mV =re Env' -VN= +Viu -0.2 Couns Supply Cunt Jw=0 50 I. =200.0mV :Note 51 Linearity Full Scale= 1:0.2 C«,rts Analcg 2ia5Kft 200mV COMMON DeMen or Fel Scale - Voltage NEW IDEAS AND 2.OQìV 3os Supply INNOVATIONS IN R Vcw = -1 V, 50 ON TCoeff of Mk() Detween 60 ELECTRONICS Vi. =0V FLiI Scale - CiavtMON w SppBiy 200.DmV u The newest ideas and Pk-Pk Segment J -toV - 5 Noise (Pk - P,< Vi. =0V 18 µV Dore VSltage 9V innovations in Ft/I Scale electronics appear in - Pk -Pk J- toV - 5 200.0rriV Backplane -9V Radio -Electronics`, V1.0-0V 1 pA Drtre V7nage Keep up -to -date! =2.@ Input Subscribe Today! PARTS LIST FOR THE POWER PLAY

SEMICONDUCTORS R5- 100,000 -ohm BR1- 1.5 -A. 100 -PIV fullwave bridge rectifier R6 -1000 -ohm 1% BR2, BR3-.5 -A, 100 -Ply, fullwave bridge rectifier (or R7 -- 50,000 -ohm trimmer poteniometer four 1N4002 rectifier diodes) R8- 10,000 -ohm trimmer potentiometer 330 -ohm D1 D4- 1N4002 1 -A, 100 -PIV, rectifier diode R9- D5-5.1 -volt Zener diode CAPACITORS DISP1 DISP3 -7- segment common -anode LED displays C1- 2200 -1F, 50 -WVDC electrolytic 01- 03- 2N3906 general -purpose PNP silicon 35 -WVDC tantalum transistor C3, C9 -10 -µF 35 -WVDC electrolytic U1- LM317T positive adjustable regulator. integrated C4, C6, C10 -1 -p.F, 35 -WVDC tantalum circuit C5- 1000 -µF. 16 -WVDC electrolytic U2, U3 -7805 positive, 5 -volt fixed regulator, integrated C7- 500 -µF. 16 -WVDC electrolytic circuit C8- 0.33 -µF. 16 -WVDC tantalum digitial (A D) converter, U4- CA3162E anolog -to- ADDITIONAL PARTS AND MATERIALS integrated circuit (Jameco Electronics) U5- CA316E 7- segment decoder driver, integrated F1 -0.5 -A fuse, type 3AG circuit S1 -4PDT toggle switch (Dick Smith Electronics) S2 -SPDT toggle switch RESISTORS S3 -SPST toggle switch (All resistors are 1/4-watt, 5% units, unless otherwise T1 -32 -volt. 1 -A secondary, stepdown transformer noted.) T2 -Dual 12 -volt, 180 -mA secondary. stepdown R1-220-ohm transformer (Digi -Key) Printed -circuit or perfboard R2- 5000 -ohm potentiometer materials, enclosure, IC sockets, fuse holder, line cord, R3-1 -ohm, 2 -watt spacers, dry- transfer letters numbers. wire, solder. R4-330 -ohm hardware, etc.

We'll look at the assembly in terms ul perlboard con- switch in the %oltage position. Power it up (with a 5 wit struction. Start by tentatively arranging the major parts in an supply) and short pins 10 and ll of U4 together. All three orderly manner following the flow of the schematic as much digits and the decimal point should light. as possible. Install sockets for the IC's on the board, and If not, check all the usual things again -polarity of the bad place a dot next to pin 1 of each socket. Marking pin I helps to diodes and capacitors, solder bridges, bad solder joints, keep down confusion when wiring. Now, following the sche- wiring, and flux residue, all of which can make things go matic diagram in Fig. I. begin installing the support compo- haywire. When all displays light, adjust R7 until you get a nents one at a time, and connecting them at the proper points reading of zero point zero, which may be a little touchy. as you go along. When soldering, keep in mind that semicon- Then connect a separate power supply to the system ductors are thermally sensitive; too much heat and they'll positive and ground outputs, along with a voltmeter of good self-destruct. accuracy, and adjust R8 until the readout matches the stan- Once all of the circuit -board assembly is completed, pre- dard. Use a voltage of 15 to 20 volts for calibration. That's all pare the enclosure that is to house Power Play. Keep in mind there is to it until everything is all buttoned up when you may that the LED display board, potentiometer R2, three jacks, need to tweak R7 and R8 again. and three switches will be mounted on the front panel. All of Before leaving you to your own devices, a couple of words the parts will require a certain amount of clearance, so mount of caution may be in order. First, take special care to properly the taller items such as radial electrolytic capacitors and insulate, separate, and isolate the incoming AC line voltage. voltage regulators with heat sinks in the rear. It can be very dangerous. Don't fail to install a .5 -A fuse in In addition, it will be necessary to build a display board if the transformers' primary circuit. Also, remember that heat you don't have a suitable multiplexed display tucked away in sinks are necessary especially on UI, which needs a fairly your parts bin. When both boards are complete, check out the large one. voltmeter by placing all of the Si contacts that apply to the Having gone to all that trouble, it seems a shame not to doll it up a little with Dry- Transfer Lettering. Another idea that may prove to be highly gratifying is the use of one of Radio Shack's "new" super bright LED's for a pilot light. When hooked up to the voltmeter's 5 -volts supply bus along with a 330 -ohm current- limiting resistor, it really is bright.

3 o 0 0 ON V all of the assembly is completed. and the circuit board Orr Once MEG mounted securly within its enclosure. the project can be greatly enhanced through the application of Dry Transfer and controls. SION Lettering to indicate various switches 4.4

39 WIND WITCHER

Listen to mother natures gentle song with this hot -wire sensor electronic chime.

By Charles D. Rakes

MOTHER NATURE'S MUSICAL SYMPHONY IS WRITTEN IN much lesser degree than either tungsten or platinum, which her gentle breezes and gale force winds to be lost forever in are the best materials to use. Don't take out a loan to purchase time, but that need not be the case if you build our motionless the material yet, because you can have a ready -made hot wire Wind Witcher to decode and play Mother's soothing melodies as she drifts by. I'm sure that you have had, at one time or

another, a wind chime that clattered away as the breezes blew HOT PIEZO by, that rendered a wind- WIRE motion melody of sorts. And, if TWEETER SENSOR Murphy's law prevails at your abode as he does at ours, the good sounding chimes usually end up on the ground in pieces AIR =LOW after the first spring storm blows through. ENVELOPE DE-ECTOR Chiming in Our Wind Witcher does not use any fragile, free- swinging objects to produce it's own unusual music, but operates on the seldom utilized effect of cooling a heated wire by moving CONSTANT air and measuring the resistance or voltage change across it CURRENT to SUPPLY indicate the strength of flow. Most any heated conductor will display the effect, but to a

D.C. D.C. TO POWER ALL SUPPLY CI RCUITS Fig. 1 -The action of the Wind Witcher is simple. Power is supplied to the bulb element by a constant -current source so the variation in its resistance can be measured as voltage. The varying voltage is then amplified and sent to an envelope detector that averages the AC signal. The average signal controls a VCO which then outputs to the tweeter. 117VAC 40 for less than a buck. A #53 incandescent indicator lamp will voltage. In this way, Q3 will follow any swings in voltage, do just fine with a simple modification. That's to break the effectively limiting current flow to a specific value. The glass bulb without getting cut or destroying the filament in a constant -current source also provides protection against a siegle blow. More about that later. high -current burnout when power is first applied. The varying voltage across II is then fed to UI -a via C3, How it Works R2, and R16. The signal is amplified there x 200 and fed to Take a gander at the witcher's block diagram in Fig. I, and the envelope circuit which is a voltage doubler composed of you will begin to see how the circuit sings when the wind D2, D3, C4, and CS. blows. A two opamp voltage -controled oscillator is composed of As the air moves over the sensor, it's resistance varies, due UI -b, UI -c, and their supporting components. It is fed the to the cooling effect of the breeze. Since the sensor is feed by voltage across CS which controls it's oscillating frequency, a constant -current source, as the sensors resistance varies, which is fed to the piezo tweeter SPKRI. the voltage across it varies also. That alternating voltage is fed to a low- frequency amplifier where it is boosted up. The Building Your Own output is fed to a circuit that produces a low- frequency The complete circuit is built on a 4x4- ' / -in. piece of varying voltage in step with the air currents passing over the perfboard, with a comer cut -out to clear the power trans- sensor. former, see photo. A 2 -7/R x 5 -% x 5- %K -in- plastic cabinet A voltage- controled oscillator takes hold of the detector's houses the components with the sensor and tweeter mounted output and sings along with the varying voltage and a piezo on the top of the case, and the sensitivity control and power tweeter conveys the music to the outside world. switch on the front panel. Neither the circuit or the mechanical layout is critical so The Circuit build to suit, but keep the sensor protected and located at a The circuit's energy appetite is provided for by a twelve - high point on the enclosure for the best performance. If you volt regulated power supply (see Fig. 2). The bridge provides want to copy our model just follow the layout shown in the full -wave rectification which the input capacitor, CI, then photos and wire to match the circuit in Fig. 2. smooths out for the regulators use. A constant -current source has its output controled by tak- Breaking the bulb ing the constant voltage that would appear at the junction of The glass bulb or. a #53 lamp can be removed in the Rl and D1, and applying it to Q2. Transistor Q2 then biases following manner. Wrap a tissue loosely around the glass and Q3 with a current developed from the differe .e in v' ige place the covered bulb between the jaws of a small bench between the reference voltage at it's base -in' s collector vise. Carefully crank the vise inward until you hear the glass

11 D2 R7 J R11K 2N3904 470K IN U2 OUT BR1 7612

VC C2 + 22(1 12 Cl 7C 14 U1-a 1/4 MC3411P 500 TD1 1N4734 1316 10 i 10K 11

R15 R3 R6 1VIEG 33052 33052 118 220K C7 680pF 4 R11 I( 470K C6 .47 C4 _L- U1-c W D2 10 #1. 1 MC3461P 1N914 i 4 r

R13 3 R9 100K 1DN914 R10 100K ^ 220K

R14 1MEG R12 15K SPKR1 01 2N3904

Fig. 2 -Don't let the paralleled resistors 3R6 throw you. They are paralleled so teat you can adj JS". the total value of the r resistance by snipping one out of the circuit. 41 PARTS LIST FOR THE WIND WITCHER SEMICONDUCTORS D1-1N4734 5.6 -volt zener diode D2,D3 -1N914 silicon diode 01,02- 2N3904 NPN general purpose transistor Q3-2N3055 NPN power transistor U1- MC3401 P quad -op -amp U2-7812 12-volt regulator CAPACITORS C1- 500 -p.F, 25-WVDC electrolytic C2- 220 -1.1F, 25-WVDC electrolytic C3-47 -µF, 25 -WVDC electrolytic Here's a close -up view of the bulb filament. Notice that the C4,C5- 10 -µF, 25 -WVDC electrolytic film container cap is secured by the bayonet socket hardware. C6-47 -µF, 100 -WVDC mylar Make sure you remove all the little fragments of glass. C7- 680 -pF ceramic disc RESISTORS implode. Position the tissue over a waste basket let and the (All fixed resistors are 1/4-watt units except where noted.) tissue and glass pieces fall into it. Inspect the filament for R1, R2- 1,000 1/2-watt resistor damage. If it's okay place in a safe location until you are R3 R6-330 -ohm ready to put it in place. R7, R11-470,000 -ohm A bayonet lamp holder is mounted in the lid of a 35mm R8, R10- 220,000 -ohm plastic film container on the top of the cabinet with 6 -32 R9, R13- 100,000 -ohm hardware. The tubular section of the film holder is perforated, R12- 15,000 -ohm R14, 1- Megohm near the closed end, with six 3/s -inch holes evenly spaced at R15- R16- 10,000 potentiometer about 1/2-in. from the end, to allow the breezes to pass through. Don't worry about being perfect in making holes, as ADDITIONAL PARTS AND MATERIALS any close attempt will do just fine. BR1 -1 -A, 100 -volt, full -wave, bridge rectifier I1 -#53 bayonet lamp, (see text) SPKR1 -2 -in. Piezo tweeter (Radio Shack 40 -1383) S1 -SPST mini toggle switch T1 -117 to 12.6 -volt, 1.2 -A transformer 2-7/8x5-%1x5-'/8-in. instrument case, Radio Shack #270 -250, power cord, perfboard, knob, 35 -mm film case, etc.

of the regulator, U2, should be near 12- volts. The voltage at pin number 10 of U I should be about 6- volts. If those voltages check out OK then proceed on to setting the constant current level for the sensor. Set your VOM to DC on the 100 -mA range. Connect the Note that the power transistor is upside down. that is to positive lead to the plus 12 -volt supply and the negative lead facilitate mounting the leads on the top of the board. to the collectors of Q2 and Q3. If the current reading is between 50 and 60 mA the circuit is ready for the #53 Locate the tweeter near the back and in the center of the top modified lamp to be placed in it's socket, but if the current of the cabinet and cut a hole to just clear the back extension of value falls below or above the set limits, proceed to correct the speaker. Use the speaker as a template and drill the four the current setting. mounting holes for 6 -32 hardware, and mount it in place. If the current is too high, remove one of the 330 -ohm The perfboard holding the circuit components is mounted resistors, R3 R6, and recheck the current flow. Parallel a to the bottom of the cabinet with 6 -32 hardware and sup- higher value resistor, say a 470 -ohm and see if the new current ported with four %a -in. plastic spacers. The 12 -volt trans- value falls within the 50 to 60 mA range. If the current former is mounted in the corner with 6 -32 hardware. A power happens to be too low with the four 330 -ohm resistors in cord connects to the transformer and SI and passes through a place, try paralleling the foursome with a higher value re- rubber grommet on the back panel to the outside world. sistor to obtain the desired current flow. Rummage through the junk box and pull out the resistor supply if necessary to hit Making Her Sing on the right resistor combination. Don't place the #53 lamp in the socket until the following With the #53 bulb in the socket, place the protective film preliminary tests are completed. Look the circuit over for any case over it and set the witcher in an area where a slight breeze wiring errors or poor solder joints, and if it looks good plug is blowing. Turn the gain pot, RI6 to it's minimum resistance the witcher in and turn the power on. value and the Witcher should respond with a musical sound. Check the DC voltage at the plus side of Cl, it should be Set the gain control to suit the amount of breeze or wind that's somewhere between 15 and 20 volts. The voltage at the output passing over the sensor. Enjoy. 42 5x5 AUDIO SWITCH BOX Switch the connections between audio components without touching a single wire with this homebrew accessory.

By Sam Allen

F YOU'VE EVER HAD TO SORT THROUGH A RAT'S NEST OF PARTS LIST get the right plug and jack combination to make cables to FOR THE a device through your stereo a recording, or to play 5 x 5 AUDIO SWITCH BOX amplifier, you'll appreciate the 5 x 5 Audio Switch Box. The Switch Box provides a convenient means by which to switch SEMICONDUCTORS LED1 1 3/4 (RS #276 -041) jumbo red light- emitting between 5 inputs and outputs in any combination, and fea- -T diode tures a built -in stereo headphone amplifier that allows you to U1, U2-LM386 (RS #276 -1731) 4 -watt audio power any the outputs. monitor of amplifier, integrated circuit The Switch Box was designed to help in making musical demo tapes through a setup similar to the one shown in Fig. 1. RESISTORS (All resistors are 1.'2-watt, 5% units, unless otherwise However, it might just as easily be used in the home -stereo noted.) 2), or in practically any system setup (like that shown in Fig. R1- 100,0000 -ohm audio -taper potentiometer system where needed. (RS #271 -1732) was de- Although the Switch Box's monitor amplifier R2, R3- 10.000 -ohm signed to be used with a mini stereo headset, it is capable of R4, R5- 10-ohm driving a standard headset or 8 -ohm speakers. (But don't R6, R7- 100.000 -ohm expect hi- fidelity audio; it's adequate for monitoring.) R8 R17- 2200 -ohm the -in monitor is most apparent in The advantage of built CAPACITORS 1 reel -to -reel to cas- the Fig. setup. If you're dubbing from Cl, C2- 220µF, 16 -WVDC electrolytic sette, and there is an equalizer and reverb in the line, you can C3, C4- 0.047µF. 50 -WVDC compare the raw output of the reel -to -reel with that of the C5, C6- 4.7µF, 50 -WVDC non -polarized electrolytic equalizer or reverb simply by switching the monitor-select C7 -0.1µF, 50 -WVDC ceramic disc switch. ADDITIONAL PARTS AND MATERIALS of the The schematic diagram in Fig. 3 shows one channel J1 J20 -8- position, RCA phono -jack board (RS Switch Box; for stereo operation, two such circuits (tied to 274 -370) the same set of dual -gang 6- position switches). To make J21- Miniature 3- conductor, closed- circuit jack (RS construction as easy as possible, the Switch Box is designed 274 -250) around commonly available components; all of them may be S1 S6-2 -pole. 6- position rotary switch (RS 275 -1386) purchased at a Radio Shack or just about any well -stocked S7- Single -pole, single -throw (SPST) pushbutton on parts supplier. Although wiring the jacks and switches is off switch (RS 275 -1565) Experimenters board (RS 276 -195) 8 -pin IC sockets time -consuming, it is not difficult, making the project one 276 -170), PCB standoffs (RS (RS 276 -1995), 9 -volt battery connector (RS 270 -325), that anyone can tackle regardless of his or her level of skill. 9 -volt battery holder (RS 270 -326). knobs (RS 274 -415), 3'/,s x 81/4 x 6'/8 enclosure (RS #270 -274), dry- trans- Construction fer labels (RS 270-201). two- conductor shielded cable Begin construction by preparing the case. A metal case is (RS #278 -1276), hook -up wire, solder, hardware. etc. important for shielding, so if you substitute another case, 43 0 0 1= 1 ED 0 00 0 0 0 0 o 0 0 Q IC 00 REVERB DECK

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Fig. 1 -This hook -up diagram illustrates how the Switch Box can be used in dubbing operations. The equalizer and reverb can be placed in line with any combination of tape decks.

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LINE INPUT FROM OEVICE LINE OUTPUT FROM DEVICE Fig. 2 -The Switch Box can also be used to route signals from various stereophonic components to the amplifier or to other pieces of equipment in the system. allowing you to use all of the capabilities of your system without changing the cables.

make sure that it's large enough to accommodate the switches the (prototype. Note that all inputs are positioned at the top. and jacks and that the entire enclosure is metal. while all outputs are at the bottom. (Again, all dimensions Figure 4 shows the front -panel layout used in the author's are given in inches.) Drill holes (both fore and aft) for the prototype of the Switch Box. (All dimensions are given in panel- mounted components. inches.) You can either lay out your circuit panel in a similar The case is then covered with a protective plastic film: with arrangement or try something more to your liking. Figure 5 the film in place, the hole positions are center- punched to shows how the input /output rear-panel jacks were laid out in keep the bit reasonably stable during drilling. It's a good idea 44 R17,2.2K the and jack J1 may be used to label switch . . . locations. R15,2.2K J2 1M Qo R13,2.2K Ah J3 OQ l_ The Panel- Mounted Components > the and rear -panel drill- R11,2.2K J4 Once front- ing is complete, mount three eight -po- J5: 11=1.1.11 t_,1 sition (six four-position or 12 two - R9 position) phono -jack boards to the rear ) O Q 2.2K O . 0 0 O O _A R panel, using sheet -metal screws. It's MONITOR J6 OK for the ground terminal of the jacks case, but the center O to touch the metal if terminal touches, remove the board and enlarge the hole with a file.

With the rear panel out of the way,

R6 turn your attention to the front -panel 100K TO RIGHT CHANNEL switches. The switch knobs should be Cl J21 mounted as close to the front panel as 220 SPKR'HEADPHONE possible, meaning that the excess shaft length of each switch must be cut off. The least nerve -wracking way to ac- complish that is to clamp the waste end of the shaft to your bench and, with a hacksaw, cut off the excess. After the excess has been cut away, Fig. 3 -To keep the schematic diagram simple, only the left channel is shown; if shown, a 5/6 washer over the the right channel would be the mirror image of the left. place -inch threaded shaft, loosely mount the SELECT 5 x 5 AUDIO SWITCH BOX POWER DRILL 3/8 3 switches, and make sure that the knobs DRILL 3/8 SOURCE i 1 245 are close to the front panel. 2 3 4 . 3 4 2 4 2 3. 2 With the case complete, you are 1 5 1 5 5 1 1 14 /DRILL 1/4 ready to begin putting together the elec- OFF OFF OFFS;,, OFF DRILL 3/16 tronics. I Begin with the switches. Each 1 -1/2 OUTPUT 1/8 switch has 12 termminals around the 1/211 outside and two in the center. Turn the .4- -10- switch counterclockwise until it stops 1 1/4 1/2 3/4 1.1/8 1 1!8 1-1/8 1-1/8 1-1/8 to determine the first terminal of each, which will serve as the off position; NOTE: ALL DIMENSIONS IN INCHES is made to Fig. 4- Before you begin drilling holes for the front -panel mounted components, it is therefore no connection advisable that you first lay your pattern out on a sheet of paper. Then when satisfied with those terminals. Bend them slightly to the arrangment, tape the pattern to the front panel, center- punch the panel, and drill to mark their locations. Next turn the your heart's content. switch shaft one click in the clockwise direction, which will be input I; one more click and you're at the input -2 position, and so on. Remember that the selectors are double -pole, six -position -O O Q-1Ò © -OO -OO ® ® -tò-- swithes; one terminal (pole) is for the _0-0-® left channel and.the other for the right. 6 0-0-0-0 o- For convenience, the author arranged the switches so that all of the left terminals were on top and the right terminals on the bottom. To make it (next to) the and the 17 17 1-1/8 1 1!8 17 e17 impossible to connect input 1 17 1717 17 17 2 37. 32 32 Si 32 32 37 32 32 output of the same device together, no

connection is made to position 1 of SI; NOTE: ALL DIMENSIONS IN INCHES ALL HOLES 3/8 INCH position 2 of S2, and so forth. Fig. 5 -The rear -panel layout is made extremely simple through the use of 8- position Next run jumpers from switch to double, or quad boards on RCA jacks. However, if you already have the single, switch to connect all of the left- channel hand, by all means use them. one end extending about 3 inches over postion I terminals, and another to con- the edge of the bench. After drilling, nect all of the right -channel position 1 to use some sort of solid backing for the remove rough edges and the protective terminals together. After which, con- panel while drilling. One way to film from the case. And then rub -on nect all of the position 2 terminals to- provide a solid backing is to clamp a lettering may be used to label the switch gether in the same manner, continuing piece of 2 X 4 to your workbench, with and jack locations. until all of the terminals are properly connected. 45 This photo shows how the rear jacks are labeled.

Place the IC socket for U1 so that pin 1 is in hole E -17. Pin 1 on U2 should be in the hole corresponding to F -8.

Test -fit the switches and other components in the case before proceeding with construction. Washers on the switch shafts will allow the knobs to be placed closer to the front. Next insert the capacitors in the locations indicated in the text: check their placement and oriention before solder ng.

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Insert the parts from the top of the board. Clip the leads to length and bend them over against the foil then solder them in place. When several parts are in close proximity. solder all of the leads at once to avoid closing off a hole with solder before the part is inserted. Insert the resistors into the holes listed in the directions.

Switch S3 lines up with the input terminals on the circuit cables should be long enough to reach from the switches on board. Solder two -inch lengths of wire to all eight active the front panel to the jacks on the back panel. Attach the two terminals of S3. Also solder wires to the position 3 terminals center conductors to the two center terminals on the switches; of switch S4 since the number-three input is not connected to one terminal for the left channel and the other for the right. S3. They'll be connected to the circuit later. Solder short pieces of insulated wire to the shield of each Next cut five pieces of shielded, two -conductor cable. The cable and insulate the connection with tape or heat -shrinka- should be about two inches long. The ground lead connects to hole X -3, the left channel to A-3 and the right to A-5. Solder short. insulated wires to LEDI and insulate the connections with tubing. Attach the anode lead to the circuit board at A-1 and the cathode at X -I. Attach 3 -inch leads for the power switch to the circuit board at H -2 and J -1. The components can now be mounted in the case. Attach the PC standoffs to the case but leave the PC board unattached for now. Place the volume control and the switches in their holes and secure the nuts. Push the LED into its hole in the front panel; it should fit tightly to stay in place. If the LED is loose in its hole, use a little glue to secure it. Put the headphone jack in place on the front panel and secure it. The power switch pushes in from the front of the panel and is secured with a nut on the back. After it is in place, connect it to the circuit board. Solder a three -inch long lead to the "Y" ground bus on the circuit board. Scratch the paint from a Clamping the switches together like this makes it easy to area on the bottom the case and solder the ground connect all of the jumpers between the terminals. Space small of them about the same distance as they will be on the front lead to the case at that point. That ensures a good ground panel so that the leads will be the correct length. connection to the case providing shielding from outside noise. Attach the battery holder to the case with a small machine screw and a nut. Place the nut on the bottom and cut the screw off flush with the nut. Now connect the shielded cables from the circuit board and the switches to the jacks on the rear panel. The cable from switch number I connects to output jack I (left and right), switch number two to number two output and so forth. The cables from the circuit board attach to the input jacks in as follows: left input jack J1 to position J -47 and right input jack to J -46; L2 to J -44 and R2 to J -43; L3 to J -4I and R3 to

0 3 2 HEADPHONE JACK TERMINAL LAYOUT

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Before installing the switches and circuit board, solder the leads from the switches into the holes listed in the text. RIGHT SPKR ble tubing. Connect all of the shield wires together and then LEFT SPKR. solder a short lead from them to the X ground bus on the circuit board. Now connect the leads already soldered to switches S3 and S4 to the circuit board: left- channel. position I (LI) connects to the circuit board at position A -47 and right -channel posi- X-3 A -3 A5 tion 1 (R 1) to A-46; L2 to A-44 and R2 to A-43; L3 to A-41 and Fig. Headphone -jack wiring diagrams. The upper drawing R4 to A -37; L5 to A-35 and R5 to 6- R3 to A-40; L4 to A-38 and shows the terminals layout for the jack specified in the A-34. Solder two leads to the center terminals of the monitor - Parts List; if another type is used, terminals may differ. select switch and connect the left- channel lead to hole A -23 on the circuit board and the right to A-22. J -40; L4 to J -38 and R4 to J -37; L5 to J -35 and R5 to J -34. Attach two -inch lengths of wire from volume control RI to When attaching the cables to the jacks. twist the shield the circuit board. With the control placed so that the terminals wires into two leads and attach them to the two ground are on the left side as viewed from the front, the top two terminals. terminals are the ground terminals; connect them together Connect the cable from the headphone jack to the two and use one lead to attach to hole X -17 on the circuit board. speaker terminals on the rear panel. The two jacks above the Connect the center terminal for the left channel to hole A -I9 speaker jacks are unused. and the right channel to A-18. Snap in a 9 volt battery and the unit is ready to test. The bottom terminal for the left channel attaches to hole A-2I and the right channel to A-20. Wire the headphone jack Circuit Board Assembly as shown in Fig. 6. Use a piece of shielded cable long enough The author's prototype was built on a pre- etched board to reach from the front panel to the rear-panel jacks for the (available from Radio Shack) on which each hole is identified speaker output. The leads that attach to the circuit board by a row letter and a position number. Fig. 6 shows the parts 47 VOLUME CONTROL HEADPHONE TO S1-S5 LED r--- Cr EEND " + - GND L R GND R L R L R L 5 4 3 2 1 O O 0p00 0 0 oq 00 çp 00 R L R LI RL RL RL 1 10 15 25

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5 20

3 INPUT JACKS Fig. 7 -This diagram shows the position of the parts as viewed from the top of the board. Refer to the directions for circuit -board construction for the exact grid number for each lead.

layout of the circuit board as viewed from the top. The and GND shield XX to Y-44; L3 to J -41, R3 to J-40, and GND following instructions give the location of each part on the shield XX to Y-41; L4 to J-38, R4 to J -37, and GND shield circuit board. When you insert the component, clip and bend XX to Y-38; L5 to J -35, R5 to J -34, and GND shield XX to the lead over to mechanically hold the part in place; then Y-35. solder with a low- wattage iron. Where several parts are close 7. When all soldering is complete, install the IC's in their together, you may want to wait until all of the leads are in sockets. Be sure to line up pin I correctly; the two IC's are place before soldering, so you won't have any trouble insert- oriented with pin 1 on opposite sides of the board. ing adjacent components. I. Mount the IC sockets on the board (see Fig. 7). The first Operation socket is mounted so that pin I is in hole F-8. The second Various audio components are connected to the Audio socket is turned around so that pin I is on the other half of the Switch Box through shielded cables. The output of the device board in hole E-17. connects to the input of the Switch Box, whose output (in 2. Jumpers are used on the top surface of the board to turn) connects to the input of another audio device. Switching connect some of the traces. Bare wire can be used for the can be accomplished with or without power turned on, be- short jumpers but insulated wire should be for longer runs or cause power is needed to operate the monitor only. Battery whenever one jumper crosses another. Keep the jumpers power is used to avoid any possibility of introducing hum into short and run them as directly as possible. Install jumpers between the following pairs of holes: J-25 to Y-25; J -9 to Y-9; J -11 to Y-I1; A-14 to X -14; I -1 to 1 -15; H -15 to B -10; C -11 to E -6, G -14 to F-6; F -5 to E-3; F -18 to E -18; H -10 to J-19. 3. Mount the capacitors, referring to the Parts List for their values. Be sure to observe polarity where indicated. Install the capacitors in the following pairs of holes: Cl between C -6 and C -5; C5 between I -19 and H -18; C2 between + H -6 and H -5; C6 between D -15 and D -19; C3 between H -14 and F-13; C7 between H -1 and Y-2; C4 between D -Il and E -13. 4. Mount the resistors in the following pairs of holes: RI between D -1 and G -1; RIO between D -37 and G -37; R2 between G -10 and Y-10; RH between D -38 and G -38; R3 between C -15 and X -15; R12 between D -40 and G -40; R4 The completed project ready for testing. between A-13 and X -8; R13 between D -41 and G -41; R5 between J -13 and Y-17; R14 between D -43 and G -43; R6 the circuit. For limited use, the battery lasts a long time. But between B -20 and B -22; R15 between D -44 and G -44; R7 if desired, a power supply could replace the battery. Just be between E -21 and E -23; R16 between D -46 and G -46; R8 sure that the power supply is well shielded and filtered. between D -34 and G -34; R17 between D -47 and G -47; R9 As an initial check, turn all of the output switches to OFF between D -35 and G -35. and the monitor power ON. Turn on all of the devices con- 5. Connect the battery clip with the positive lead to J -2 and nected to the box and set them for some type of output (play a the negative lead to Y-I. tape, turn on the FM tuner, etc.). Now turn the monitor -select 6. Cut five 4 -inch lengths of two conductor shielded cable switch to each of the different settings. You should hear the and attach them to the circuit board as follows: LI to J -47, RI output of the selected device in the headphones. Next try to J -46, and GND shield XX to Y-47; L2 to J -44, R2 to J -43, recording from one device to a tape deck. 48 .1111SMM I1114. 1v.. 1 D K. III« nN1N M.. I.1, 211111 w4« ...1 I,«+IW N 1411 1RMM11+C« 4411

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IF YOU'RE INTO APPLICATIONS-ORIENTED PERSONAL COMPUTING the printer off the line, or it can be a complex program rather than technical hacking, or if you're a newcomer that literally restores disk -based data that you acciden- to personal computing with an IBM PC or XT "clone," tally erased. A utility can be software obtained free -of- or a compatible machine, there's a good chance that you're charge from bulletin board services (which are called finding life in the fast lane bewildering at the very least; BBSs), included free with magazines, sold in stores as totally confusing at the very worst. Either way, you get an individual program or as part of a collection of pro- neither the pleasure nor the power of personal computers. grams, or made available as shareware. Obviously, share- There are several reasons for that situation, chief among ware takes some explaining. them being that many PC /XT clones are really dealer- Often, the costs for advertising a particular program assembled, using components from many different manu- would prove greater than the gross sales, so the author facturers, each with it's own individual operating man- makes the basic program available free through bulletin ual; and except for a few mimeographed pages provided boards. If you like the program and want registration so by the dealer, nothing ties it all into a system, or gives a you can get enhancements, or if you want a decent man- really good explanation of how to use the supplied soft- ual instead of the brief READ.ME file that comes with the ware (if any is supplied). program, you send the author a stipulated- usually On the other hand, a complete, brand -name system, modest -fee. such as an IBM or an ATT, comes with manuals that are Some top -quality software and utilities, such as the comprehensible only to the true computer hacker. Oh, famous communications program MITE and the equally you'll get the gear to work all right, but often you'll be famous random database utility SEEKEASY, are avail- doing things the hard way, and asking yourself, "Does able as shareware. We'll talk about some of them personal computing have to be all this difficult ?" You later on. will see that the answer is, "No!" Where Is It? Utils Taking first things first, let's look at how a directory The art of personal computing isn't difficult at all if you utility known as D.COM can simplify finding disk files. use software widely known as utilities, which is usually Even if you use a floppy, you can end up with enough files shortened to utils. Utilities are -easy -to -use programs that to flow off the bottom of the screen when listed by the get around problems and hangups of the computer hard- DIR command. If you have a hard disk it can be even ware, the supplied software, or "store bought" programs. worse. Of course PC -MSDOS does try to make things A utility can be a short routine that simply advances easier by giving you the DIR /P command (see Fig. 1), the paper in your computer without your having to take which presents a screen full of directory entries at a time. .17TH (OM 627 3 -17 -86 2: 46M

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Fig. 1 -This is how your directory listing will look when Fig. 2- Here's the same directory as in Fig. 1 but using you enter DIR P. Only part of the directly is available. the DIR, W command. Time, date, and size have been stripped. If you count down to the fifth line in Fig. 1, you'll see the pre, my hard disk contains several subdirectories that might cue from the previous screen display that says to strike a contain text files. Once, months after it was written, I had key to see more entries. You'll also note that the listing to locate a letter written to the IRS. I had no idea which isn't sorted, and that the PRESS and PS subdirectories are of many subdirectories it might be in. Since I use the intermixed with the regular files. extension .LET only for very important, or libelous letters, To make a directory somewhat easier to read, PC- I got the chase going with SFIND.COM. MSDOS provides the DIR/A/ command illustrated in Fig. As shown in Fig. 6, I entered SFIND *.LET which meant 2. DIR/W strips out the date, time and size information find all files with the .LET extension in my hard disk. from each listing so the display can be compacted into Within seconds it had found the only two files with the five columns. Unfortunately, the listings stil I aren't sorted, .LET extension: IRS.LET in the \ LARRY subdirectory, and and the subdirectories are still intermixed: They're the TELNASTY.LET in the \ TEXT subdirectory. listings without extensions, such as COMCOR, SAFETY, Since I knew I was really looking for a letter to the IRWIN, etc. Internal Revenue Service, as shown in Fig. 6 I could have Now look at Fig. 3, the same directory as displayed used the " ?" wildcard and entered SFIND ? ??? LET, which by the utility program D.COM (available via many BBSs). as you can see in Fig. 6 will quickly find the file in the Firstly, the subdirectory clutter is gone -no subdirectory \ LARRY subdirectory. is listed. Next, and more important, the disk files are sorted Why did I use four wildcards ( ? ? ? ?) for a file with only alphabetically, which makes it much easier to locate a three characters. Because there might have been more particular file. And the size of each file is shown; which than one IRS file, perhaps IRS1, IRS2, IRS3, etc. The corn - is often a specifically desired bit of information. puter can usually find what you are looking for up to the limit specified, but not necessarily more than specified. The Bigger, the Easier If I had entered SFIND ?? ?.LET it would not locate IRS1.LET Now you might say, "Big deal! So D.COM puts every- (which has four characters before the dot). The general thing in column form." That was a simple illustration. rule for wildcards is to specify more than you need, al- Look at Fig. 4, a DIR/W of a subdirectory of one program though some utility programs are very fussy and will only with many overlay files. Compare the DIR/W listing with give a precise wildcard match: e.g., four wildcards will that of Fig. 5, a D.COM of the same subdirectory. Which match only four characters. would you rather work with? Several variations of D.COM are available, such as Don't Get Burned DDIR.EXE, DDIR.COM, etc. Most are similar except they Another outstanding freebie utility came with a disk are limited to two, possibly three columns of data, with supplied with the premier issue of Computer Shopper's overflow listings held for another screen display. D.COM PC -Clone Magazine. This one resolved something that's uses four columns and can display files 80 on one screen. been a pain in the tractor-feed since I got my first printer back in '79. The utility, called BLANK3.COM, has two Dumping It In separate functions, which are shown on the screen when Another convenient utility for just about everyone is the program initializes (Fig. 7). Firstly (and this seems to SFIND.COM, which came as a freebie in a disk magazine have been its original purpose) it blanks the screen if a called UPTIME. In the game of hockey, one team will try key has not been depressed for three minutes. The display to clear the puck by dumping it across the Blue Line; returns the instant any key is touched. then everyone chases the puck. Getting the chase going Supposedly, the screen image will burn in if left on is called "Dumping it in." Well, a there's "Dump it in" permanently. While I have seen it happen on an oscillo- when it comes to locating a files on hard disk. For exam- scope, only once have I seen a burn -in on a computer 50 Directory of disk E: E \PRESS>dir'o 1DII .CON 13772 E has no Intel ATTB .COM 627 Volvae in drive E \PRESS AUTOIXEC,MK 265 Directory of AUTOIXEC.IAT 264 - STARTUP BAT STARTUP 811 STARTUP 802 BACKUP .8_1125888 PRESS IXE COMM IAT STMIAII SHP STARTUP 883 STARTUP 184 1L1863 . COM 628 MAIM SHP F08S1 FSZ FOIFTS1 FIM STANDARD SDR PATTICON SHP CLIIMIT .cal 1249 IAH FIC 106DERS1 1IC IORDEBSI BM 1081[151 17792 8011701 MUM FORME COMMAND .COM ASC HS ASC H4 ASC H3 ASC Hb C0MF1G .SYS 105 SCR TXT ASC ?IMPRESS ASC ?IMPRESS PIT IEVILLE riff COI 2222 82 ASC Hl D FIT WESTER FNT OFFICE FMI HAMPTON FIT TRI186E DPATH .COM 16384 SCIIIE Flit FIT EDITOR FMI III PM 11% UTOPIA FIT COMPUTER FMI SMALLCAP DRIVER .SYS PIN LRISI8 PM I RM_PRO [8506 -FX PAN 061 -82 866 TOSHIBA PIN PAINT .TMB 13% -111 PM STAAGDI PIN C_ITOH PAN 011 8ITS800L.COM 6197 011 -STI PAN IDS PRM O1P2166 PIN AYOLASEI PM IATA880) PIN DMP165 PIN IMP120 PIN C8M6 . D([ 16246 MI UP PS IAT PS SFIND .COM 2518 118116 PIN DMP488 PRN SET IUSIMESS SNP TRAVEL SHP TRAVEL SDI SPOOL .BAT 28 GIAPHIC2 SNP GRAPHIC2 SDR SHP STATLINE.COM 189 BUSINESS SDI CUSTOM SDI CUSTOM WIZ .COM 32896 68 Filets) 2688968 bytes free XTCLOCK .COM 1224 C NIESS> Era. 8 Files. 164,484 (7,983,184) Used. 2,681,968

Fig. Compare this display with the one in Fig. 5. Both Fig. 3 -The D.COM utility is what directory users want -a 4- subdirectory. Which one do you prefer? file listing (up to 80 per screen) void of date, time, etc. are of the same monitor. Someone running a BBS had set the monitor's brightness and contrast controls to maximum. Since the Directory of disk E screen display rarely changed, after several weeks of the .FIM 168 0l1-IM .PM 478 TOSHIBA 6061E851. IIC 28688 FONTS] PM 495 a day the image actually burned in. 948 011-STI 181 555 same display 24 hours 1011E1514Ni 176 F041151 .FSZ TIIEL SII 2176 MUM 2 PATTICON. SHP 2432 TINJEL IORPERS1. NUN 128 F0IFS1 .SHP 75111 80518(SS.SIR 1928 GAAPHIC2.S811 2256 PRESS .IXE 64964 T111181E PII 6788 888% 'IMPRESS ASC 35971 UTOPIA No Printer Blues IUSINESS.SHP 69285 CMPHIC2.SHP PIP 3186 945 'IMPRESS 11826 WESTER is an automatic COMPUTER. FIT 5868 HI ASC PIT FTT 3762 The second feature of BLANK3.COM CONFIG .1AT 26 82 .RSC 1811 PS . MI 85

83 .ASC 846 PS . MT 53 printer form -feed, and that's the one I consider a real CUSTOM .SUI 32 CUSTOM .SNP 1154 84 ASC 1381 SCI .TXT 1971 winner. I would be very wealthy if I had a dime for every C_ITOH PM 387 115 .RSC 913 SCRIBE .8168 12524 set off alignment. DATAP60D.PIN 368 86 .RSC 691 SR .UP 27 time I started a print with the paper DLVILLE FIT 18574 14118808 FIR 5598 SMALLCAP. ENT 1858 Normally, that comes about when you make a screen DM8165 PM 586 III PM 368 STMM61.S16 1952 the OMP116 PIN 998 IIM_PRO .PIN 368 STMMII. SHP 78394 when . 359 print (SHIFT- PRTSC) and simply tear the paper off 888126 PIN 986 IDS . PM 617 STA10D1 PM printer stops. Or maybe it's from a word processor or 8P2116 PRN 498 IYOLASEI. PM 479 STArrUP .811 999 DMMM . PIN 541 L0150 .881 433 STARTUP .812 5% database that stops the printer cold after the last charac- EDITOR .FMI 1266 IRIN .SH? 8448 STAIIU? .813 1111 EPSON-fX. PIN 361 OFFICE .FMB 5558 STARTUP .811 1115 ter. Whatever, I either forget to realign the paper or to set FOIRSI .FIC 3926 OKI -82 .PM 524 STARTUP MT 124 back on line. With BLANK3.COM those prob- the printer t \PRESS)_ 66 Files. 561,754 17,983,111) Used. 2,688,961 fr«. lems are eliminated. At any time, from DOS, or from inside a program, the paper will automatically form -feed or complete a form - Fig. 5-If you picked this screen display over the one in I ALT -F. It's a really outstanding conven- feed when press Fig. 4, D.COM is the directory -listing utility for you! ience that cannot be fully appreciated until its used. Normally, the best way to handle BLANK3.COM is to make it part of your AUTOEXEC, because it doesn't seem to interfere with any programs (so far). The program cre- E vrfind .let ates the screen display shown in Fig. 4 to let you know 12 -28 -87 it's active. SFind Version 1.12-X, Searching drive [: for (99999999 LETI

Save My Baby! IRS. LET - [ALAINY\ Perhaps the most dreaded command in personal corn - TELMSTY. LET - t: \TFXT\ puting is the accidental file or disk delete. Most of us at 2 Filets) found

one time or other has inadvertently and stupidly issued E: )ef ind 9999 let Contrary to a DEL *.* for the wrong disk or subdirectory. SFind Version 1.82 -0, 82 -28-87 common belief, neither the inadvertent DEL *.* or even Searching drive E: for I ?? ?? .L1Tl a FORMAT of a hard disk is irrevocable, at least for the PC-compatibles. Some other computers have their files IRS. LET - E:\LARNY\ go belly -up when accidentally formatted and nothing can 1 Filets) found save them. E \>_ Both freeware (via BBS) and store -bought utilities are available that will recover a deleted file if it hasn't been written over. That is because the DEL command doesn't actually erase the data. Instead, it changes the first char- Fig. 6 -The author looked through several subdirectories to acter of the directory listing and frees the file's space in uncover the letter he needed by typing SFIND ? ?? ?.LET.

51 /IrreNNl IIb Mb Tltw Kag..

POS %11811 .ClO 2511 83i18/1987 15:38:18 *0S N rTATLINE.COM 119 82/16/1986 17:33:11 Xy rTAMTUP .IAN 166 88/0S/1987 15:58:89 ICY ,MINT THE 6969 89/28/1987 22 OS 89 XY IEEE .80 15421 89/27/1987 12.88.83 XY rTIL .TXT 1% 89/29/1987 88:3388 XV t rUTOFXEC.IAT 264 89/29/1987 88:33 85

A>e

E>Ilanh3

Alt -F will send a for.feed to your printer.

Fig. 7 -The display tells the story. BLANK.COM darkens the Fig. 8 -Mace is a nice word when it restore files that are screen in three minutes and can formfeed your printer. belly -up because you responded yes to an DEL command. the FAT (File Allocation Table). We usually simplify Solving Fragmentation the explanation of the DEL process and simply say As you know, when you write to a disk the DOS that the directory listing is eliminated, and if the com- finds fragments of unused disk space and spreads the puter can't find a filename in the directory it can't data over the fragments. The more writing and deleting find the file. you do the greater the fragmentation. It takes time for a head to move from fragment to fragment when reading What is Restoration the data. Unfragmenting (repacking) re- writes fragmented As a general rule, you can figure out what the first data into segments that are read in order by DOS. (That's character should be if you know all the other characters. technical- hacker stuff we won't get into at this time.) The An undelete utility will list the files and allow you to speed -up in accessing data can range as high as 50 %, restore the correct first character, thereby undeleting the depending on the specific data and the degree of previous file. (Of course, the FAT is also restored.) However, it fragmentation. must be done before you write anything to the disk, be- As a general rule, the process of unfragmenting also cause the space used by a deleted disk file is "free." A repacks the entire disk so that all files are pushed as close write can use the space, and even though you restore the as possible, with the empty segments together after the directory's filename, there's no longer a matching file used segments. That process not only speeds up the reads, on the disk; you'll see bits and pieces of other files- it keeps the most recent writes unfragmented. Figure 9 whatever used the space. The utility will usually tell you shows the screen display of disk utilization after MACE if a file can be saved. For example, the highlight in Fig. has unfragmented and repacked a disk. Notice that only 8 shows the file to be undeleted, but the display shows a single cluster on the seventh line down is unused; it is the file is probably erased, meaning its disk area has been from a file that was erased after the disk was repacked. used for some other file. Undelete software generally works well on text files. Locking Out a Cluster I would not want to bet the farm that it will restore a A side benefit to untragmenting and packing is that program -a .COM or an .EXE file. More often than not, defective and "weak" disk clusters that might have devel- at least in my experience, .COM and .EXE files will not oped are locked out, much in the way a conventional be properly restored. format locks out defective sectors. As shown in Fig. 10, which is a MACE display from Restoration Plus my WordStar 4- equipped computer, unfragmenting once As a general rule, free undelete utilities do only that saved me from losing Wordstar's spelling checker. Ac- function. When they are part of a commercially -sold util- cess to the spelling checker was getting more difficult ity, such as MACE + , the undelete is only one of many and read errors were becoming more frequent. So I did utilities. For example, MACE + can recover files from a a repack, hoping the utility could read the weak data, hard disk that has been accidentally reformatted. The because it will try 10 times before it quits. Sure enough, latest version of MACE even has a special FORMAT utility on the fifth try it read the data, repacked the sectors, and for computers that normally destroys data if acciden- then locked out the defective cluster forever. tally formatted; the special FORMAT command is com- Figure 10 shows how the lock -out recently appeared patible with other formatting software, but doesn't when I ran a periodic MACE test on the hard disk. On the destroy data. second line down, near the right, one cluster has a faint Another outstanding MACE utility un fragments and X mark, meaning it is locked out. It can never be used. repacks a hard disk, which can substantially speed up Mace saved the cluster's data and moved it to a good disk access. cluster during the repack. You can also see the fragmen-

52 J JV ......

grg

- ssed, = free, X = lockedont

for this foret, each 0, , X equals 1 clusterlsl, or 16 sectorlsl. Files P = Position sensitive Diagnosis ended at 8:89:56 Elagaed tine 8 hours 4 minutes 4 secods suss any key to meters to emem.

Fig. 10- Defective and "weak" disk clusters are locked out Fig. 9 -Mace can fragrement and repack a disk for better way FORMAT.COM locks out defective sectors. memory utilization and give a graphic of what was done. by Mace the tatioll (dark clusters) caused by erasing text files. If it gets much worse I'll unfragment the data so it more closely

resembles the display shown in Fig. 9. E>ATTR l+Sl -S1 ( +H1 -H1 l+h -Il ldrive:llpathlfileums Syntax ATTI f +pl-RI Archive System Hilden leal -Only Hide the Files E> E> Getting back to freebie software again, a classic favor- E>ATTR .CON your software is 111110 CON Arc Sys Nid A -0 ite when others will be handling IIMDOS CON Arc Sys Hid R -0 ATTR.COM, available from many bulletin boards. lDl R. COft ASTI CON ATTR.COM (attrib) is similar to the PC -MSDOS ATTRIB CLRINIT.COM Arc 1-0 only it's more useful. As shown in Fig. 11, COMIAND. COf1 Arc command, D. CON ATTR.COM can display whether a file is archive, system, DPATH CON PRTSPOOL.COM hidden, or read -only. It also allows you to change any SFIND C0M its Further in Fig. 11 you see STATLINE cal function to opposite. down Y12 CaM the attributes for the files in my computer's root directory. XTCLOCR. CON Arc I -0 ILANI3.COM Note the famous IBMIO.COM and IBMDOS.COM files Arc which are usually not shown during a DIR. ATTR.COM note only shows you all the files, but their attributes. Note that IBMIO.COM and IBMDOS.COM are also system files, hidden -meaning they won't be listed by a DIR command, and they are read -only. Fig. 11- ATTR.COM is more useful than MSDOS ATTRIB. It can a is system, hidden, or read -only. Notice that I have used ATTR.COM to set CLKINIT.COM say when file archive, and XTCLOCK.COM to R -O (read -only). These are the programs used to set my computer's automatic date and it seemed that substituting software for time stamp, and F \>VEREC THAN ou - YORDPROC iETTERS r a different clock module -which drove my autoexec'ed UGHINE REPLIES boot -up crazy-was the highlight practical joke of some 60VRNNNT ACTION PERSONAL people who had access to my computer. By setting the L:: read try as they might, they could neither - SPIEAD TAXES FEDERAL filessn to -only, L STATE CITY delete nor substitute other software for my computer's - IOHLINC - VACATION 1986 clock. 1987 1988 Also, I have some text files which are no one's busi- - HOME ness, but my own. By making them hidden files they don't - AUTO

RECORDS HOME , I I there I appear on any listing, yet since know they're IMrROUs DEDUCT can access them through my word processor. L NONDEDUC IIUSINESS FAMILY NANCY BBS CELIA More From LAIR Another favorite utility from a BBS is VTREE.COM which I- 11E11 is very useful when moving between subdirectories. I'll just give you an illustration of what it can do when a disk has so many subdirectories you can't keep track of what went where. Fig. 12 -Look at the display when you type VTREE and If you have ever used the DOS command TREE to lo- you'll know what subdirectories you have and where they are.

53 Statistics

TINT DUS 1111 H Ileh Usage 1 SISIMSY 5111 -111 r Blob Usage 1 3I 815152 PRO 2111 11 User files BMITIIY SUP -111 2 Hidden files COMMAND COO 25307 2600968 bytes left TUT SU -1I1 20 User files DICI SPL 110161 946176 bytes used N AWl-Ill 2600968 bytes left MEW EDITOR EKE 173728 10584064 bytes total YS1 SUI-111 221184 bytes uses HERB BAR 7775 MALI PUF-1ll 18584064 bytes total HERB SPL 7772 KY SUF111 LONG HLP 199933 M_sry Ibap as IDIR 43772 Memory ruge 11 PRINT TOP 9123 475872 bytes left ATTR 627 475872 bytes left SERIAL BAT 18 179188 bytes used AUTOEXEC 265 179488 bytes used SPELL OUR 22432 655360 bytes total AUTOTXEC 264 655360 bytes total STARTUP INI 162 BACKUP 25088 TIQUE -1 HF 11915 Irr Today Is 444 BLANK3 628 Telay Is /aa AFRO SYR 325952 Saturday the 3rd CLKINIT 1249 Saturday the 3rd WORD COMMAND OUR 22784 8 SI 16pm 17792 8:50: IIA

ills Compose

Quble - Camarillo, Ca. Licensed by Bourbaki. Inc Icl 1983. 1984 He Licensed by lourbaki, Inc Icl 1983. 1984

Fig. 13 -1 DIR lets you select the XY subdirectory from one Fig. 14 -Press enter key (Fig. 13) and the XY subdirectory of the formatted on your hard disk. Now press ENTER. is displayed. The highlight is positioned to run XyWrite.

cate a subdirectory you have learned that the eye must LINE.COM, usually available from a BBS. STATLINE cre- be quicker than the hand, because the listing flows right ates a 25th line with indicators for the condition of the out the top of the screen. On the other hand, VTREE.COM three "guess me" keys. produces a screen display such as the one in Fig. 12, Figure 15 shows a typical STATLINE display as it ap- which shows precisely how the various subdirectories pears when running a program. The "up arrow" symbol are interconnected and interrelated. If VTREE can't find means the CAPS LOCK is set; the tic-tac -toe symbol means the the subdirectory you're looking for, you probably have NUM LOCK is set so the numeric keypad functions as a cursor made a gross error in creating your subdirectories. control; the up -down arrow means the SCROLL LOCK is set. The program isn't entirely perfect. Some word proces- And the Kitchen Sink sors, such as Xywrite, provide their own screen display BBS utilities usually provide only a few functions. Store - for the "guess me" keys so the STATLINE display is redun- bought utilities usually throw in the kitchen sink in order dant, or it simply freezes on the screen. to justify their expense. One of the oldies, but still good- Other software, or certain parts of the software, will, ies, is something called 1 DIR, meaning "wonder." (Isn't as shown in Fig. 16, display as much of the first line as it that clever ?) 1 DIR is a file management utility that allows can after the three STATLINE symbols. That is particularly the user to handle files in batches: You can tag and erase true for a DIR. But it's a minor inconvenience you adjust a string of files, copy them, etc. As shown in Fig. 13, to very quickly. In most instances, the STATLINE display 1 DIR also throws in gobs of data. First, it sorts both the is very useful, and avoids keyboarding a string of 4's and subdirectories and the files; then it provides as much 8's when all you want to do is move the cursor to the left data as your mind can take without exploding. You get or right. the date and time, memory usage, and the disk usage for Take note that spillover of the first line to the statline the particular subdirectory at which you have only pointed. applies only to TTL monochrome display, not to a CGA The toggle and set -up data are self -explanatory. display. When the CGA monitor adapter is driving a com- In Fig. 13 we have elected to view the XY ( Xywrite) posite mono, composite color, or RGB color display, the subdirectory. When we press the ENTER key the XY subdi- statline contains only the three "guess me" symbols -not rectory is selected and the screen shifts to a display. Fig. part of the first line. 14, that shows the XY subdirectory files, and the highlight is positioned to run the editor program. Notice from Fig. How They Got Bigger 14 that the disk usage has changed. It shows 14 user files, Regardless how complex or intricate it might be, any- the total number of files in the XY subdirectory. one can write a program for personal computers. At least As shown by the boxed functions running across the that's the way it's told after someone else has made the bottom of the screen, you can preset the computer to do breakthrough. Until VisiCalc there was no spreadsheet almost anything to the file that's pointed at. for personal computers. After VisiCalc, everyone was an expert at writing spreadsheet software. One wonders if

An Extra Line of Data there would ever have been a SuperCalc or Lotus 1 -2 -3 If you have one of the original PCs, you have probably if there were no VisiCalc. cursed the sadist who designed the keyboard. Not for it's Similarly, we might still be plodding along with the layout, but because there's no light, or indicator of any older WordStar instead of the modern Xywrite had there kind, to tell you when the CAN LOCK is on, whether the NUM been no Electric Pencil to show how word processors LOCK key has set up the numeric pad for cursor control, really should work. or whether the SCROLL LOCK is set. As for database software for personal computers, early The solution to IBM's omissions is software cal led STAT- versions were so complex only the programmers who

54 UPS SONNY I:It3>QyY I ert IMF --Search knite: liceeeee NeH Fner.a Llneen Nevi Fried...

SILICE - ALTEMATIVI TO UPS 01 SPACE-AGI LILIVIM rDIIOL WINS - This is "SELI[ASY " CALL 714-999-6512 - 24-NI 1ILIV.

Correlatioe Systems 81 lockielhoree Seal Rancho Palos Verdes, Calif. 98274 12131 833-3462

Typo what yew wi.h to find, tie. pre.. NTtl. Pres. jul LIITTI te /brlre ap Type what yo. wish to find, thee p ORII. fret. jest LIREZ te Shipley op te edit to IN Item' Pres. ESCAPE (twice/ for lode Select, CONTNL -I (twice) te edit to IN items. Pre.. ESCAPE (twice) for Iode Select, CI8TIOL -I (tidal or (trial te It delete ally Item, abet, COIfTNL -T for herlcepy, or delete ally items eleve, COIRIOL -T for lardcopy, COATNL 4 CpRNL -8 (wla) 4 pit

111 111 BPS

a SEEKEASY display is to the Fig. 15 -The up -arrow means that CAPS LOCK is set: #, for Fig. 16. The first line of at top and bottom. the num lock; and the up -down arrow is for scroll lock. right of the STATLINE symbols. See UPS wrote them had any idea what was going on until dBase Il came along (which was really an intricate programming language that was brilliantly promoted and advertised). Of course dBase III + came along and made us all database experts. Regardless of the kind of software, no one knew what to do until someone else had developed the key to how Posse eve of the f.11eme9: it could be done. Then everyone became an instant "ex- (1) Prime 1: I0S/011 te991e was noth- (I) Prime 1: IOS/ON toggle pert," uttered their "Aha's," and claimed there (S) la tots Live( nth 1 toggle word processor, data- (C) Cool gire 011 29s ten ing to writing a good spreadsheet, (F) molt ON s11 base, communications package, or whatever. (ESC) Dnt Neu Utilities also needed pathfinders for the "experts" that Enter choice: 1p were to follow. Until Peter Norton showed how easy it was to restore deleted files, one had to be a 12th- degree ,h,,.ohl 1eC, 1904 Kura Iltterficet fmisrat.9 etrnm I. r black -belt in computer- hacking to understand how to use INI(r :; (9: (At' the "public domain" undelete software. Similarly with :l: : 001 I 0119a 11: 03 I Oi14ey! l 1 ILI::Airv: such programs as SFIND.COM, which was covered earlier. Before SFIND, one had to be at least a 10th -degree black -belt hacker to locate files. And to find specific text, even IBM's own SFIND filter (which came with PC -DOS) Fig. 17- RUNCPM has been initialized here. The user toggles was incomprehensible to the average user. either drive A: or B:, between the DOS and CP M formats. But once the breakthrough for a particular kind of software was developed, it became possible -and relatively cheap -to provide both simplified and complex version,' of utility- software packages.

Heavyweights Iestrrirod Ver. 1.111 SNlasdf l'reviously, we covered several free or low -cost, easy - MAIN 1111111 to- obtain utilities. This time out we'll look at some real erl - File Services F2 - Nish Service. heavyweight utility software: the kind of stuff you should F3 - Calce(ator use your F4 - Typewriter get into only after you really understand how to Fs - I'o Option. computer. It's not the kind of software recom- F6 - k. a Program personal F7 - Reset [.ecete Path mended for real beginners and newcomers to personal re - Printer o.tpel kdirsctio. r9 - Spool Oneee Mai.te.a.ce computing, because it can literally reduce you to tears it FIB- ASCII Tall. [SC- Snit lest f you don't know the ins -and -outs of how your computer 6 52p SATUIMY OCT 11,1987 uses paths, directories, subdirectories, and the general way in which disks interchange information and filenames. Loevrlaht (c) 1985 [lite Solwarc

Jeff CP, M Again? We'll lead off with a utility for those of you might have started out in personal computing with a CP /M computer and have so much "good stuff" on CP /M disks that you Fig. 18 -Using Best Friend you can set the options for printer. COM1:, and COM2:. and slave the printer.

55 lestrr feel VI AICII T/LI IC) I Irte >Allwre

1 N 57 39 111 1. B 8/ 8 117 93 16b A6 185 19 I 214 CC 223 It 242 rz

1 87 II SI 30 115 129 81 0 118 94 167 186 IA 255 CI . 224 Ee 243 F3 2 12 S9 31 116 e 131 82 o 349 95 168 88 187 11 216 CC . 225 El 2/1 F1 3 13 W 3C 117 i 131 83 G 158 % 169 188 IC 217 Cr f 226 12 245 05 1 1/ 61 31 111 A 132 84 ù 151 97 171 AA 189 11 I 218 N I 227 13 246 F6 5 IS 62 31 119 e 133 85 ISZ 98 171 AI 190 IE } 259 II C 228 L1 217 F7 6 N 63 IT Ill L 134 86 0 153 99 172 AC 191 IF 211 12 e 229 ES 248 F8 7 c 135 17 N N 121 87 u 151 % 173 Al 192 CI 211 D3 Y 230 E6 249 F9 0 6 136 88 C N 65 11 122 155 91 17/ AC 193 Cl s 212 D1 t 231 E7 251 FA 9 e 137 89 L I9 66 /2 123 156 9C 175 Ar 194 C2 r 213 DS 1 232 E8 251 FI 11 e 138 BA M 67 43 121 / 157 91 176 N 19S C3 214 DI / 233 C9 252 FC II II 139 81 I 61 41 125 158 91 177 I1 1% C1 215 D7 I 234 EA 253 FD 12 BC i 118 BC 69 45 126 j 159 9F 178 12 197 CS 216 DB i 235 CI 254 FE 13 111 81 r II 71 16 127 165 Al 179 n 1% C6 217 D9 236 EC 255 FF 11 0 1/2 81 II 71 17 161 Al IN 11 199 C7 L 218 DA . 237 ED IS IF 113 83 6 162 A2 72 48 101 K 2111 C8 219 DI I 238 IF 16 11 I 111 98 163 73 49 83 102 16 211 C9 228 DC n 239 EE 17 11 . 115 91 6 161 84 74 M 183 17 252 CA r 221 II : 210 FI cri.;.-Nr: S -IT 121 CI511ARIIS A D71 128 CIM IACTEIS - IRON 30 IAIA rIEAu

Fig. 19 -Best Friend offers an ASCII table mode. The most Fig. 20-ASCII codes used for the cute faces, the male and common characters are shown in the first screen image above. female symbols, etc., can be found in this display.

can't get rid of the old CP /M workhorse. Or maybe you're drive A: for DOS, and drive B: for the CP /M format. attending a school that built their computer labs seven Now we can run any way we want. We can actually years ago and still haven't gotten around to upgrading run a DOS version of a program, and read and write to to the mainstream computer for virtually all business use: a DOS disk in A:, or read and write in a CP /M format on the IBM -compatible. B:. Better still, we can actually run a CP /M program on For those in the CP /M bind, the utility of choice should B: and save its files in CP /M format on B: or in a DOS be RUNCPM. To explain: There are several utilities that format on A:. Or, we can run either a DOS or CP /M pro- allow CP /M files to be copied to PC -MSDOS disks. Unfor- gram and intermix the data reads and writes. tunately, the only value in doing so is to "save" text or We can also simultaneously toggle both drives so the data files to be run under PC -MSDOS versions of the computer can be instantly switched back and forth be- CP /M software; you cannot run a CP /M program on an tween the DOS and CP /M modes. IBM -compatible. Well, that's not entirely true. There are As you can see from Fig. 17, you can even format a utilities that allow IBM -type computers, which have 8088 disk for CP /M, configure a specific CP /M system, and turn CPUs, to emulate CP /M running on an 8080 or Z80 CPU. on the 25th status line: the line that shows which drive Problem is, the emulators are so slow they are often more is toggled for what system. difficult to use than simply doing nothing. On the other hand, RUNCPM is intended for use with Stepping Back what is known as a V20 CPU. In very basic terms, a V20 One word of caution, however. Although it is claimed is a special version of the 8088 that also contains the that the V20 will run all DOS software, in actual fact 8080 instruction set (op code). For those IBM-compatible some of the lesser -known software used undocumented computers that have been upgraded with the V20 CPU, features of the 8088, which were eliminated in the V20. the RUNCPM software permits the computer to actually After all, if the features weren't supposed to be used there run an 8080 -based CP /M program in true CP/M-not emu- was no reason to keep them. Unfortunately, some pro- lated. You can also run both PC -DOS and CP /M disks at grammers gamble that undocumented features will al- the same time. For example, if your home computer is ways be available, a gamble they often lose. It is quite an IBM clone but you're still using an Osborne down at possible that if you substitute a V20 for an 8088 CPU the shop, you could do your shop database in a CP /M some of your software-most likely a utility-won't run. version of dBase lI, and then take the disks home and run We have not found a single instance where major soft- them directly in your IBM clone under the exact same ware won't run on a V20, because they always use only CP /M version of dBase 11 that you use at the shop! the documented CPU features. (Using undocumented CPU features is often successful, but it is a sign of poor Using CPM Stuff programming.) Figure 17, the main menu of RUNCPM, should give you a good idea of the kind of magic you can expect from Your Best Friend E the utility. First, you initialize RUNCPM to the particular Best Friend is a kitchen sink utility in that it contains Q kind of CP /M disk you will be using. In Fig. 17, as shown almost everything having to do with file manipulation, wby the bottom line on the screen, you'll note that we and even throws in a "scientific calculator" having an w have initialized RUNCPM for the disk format used by on- screen "paper tape." ó Osborne's Model 2 and Executive computers. Also note Figure 18 shows Best Friend's main menu. There's prob- that ó the menu allows the user to toggle either drive A: ably stuff there you have never seen before, such as I/O z or B: between the DOS and CP /M formats. As shown on options, which allows the user to set all the printer op- z the bottom line of the screen display, we have selected tions and the COM1: and COM2: configurations at one 56 lestlriend It.i /ILI IIN16n (C/Elite Software f®DIA E TE3l7 HI/f PAM 111 A - Ito, files V - Vie. file KIM ON 15964 AIC C - Cory file W - Where's file L I GWNRI MI - - LIE011RA NF 16312 ARC I - 6.1.t. filet X X -pert mode S LIGNN1fl TXT 15964 ARC L - Execute file Y - Attr change 8010 SAN 2963 ARC F - Fi./ file Z - Set verify NONCE

1 - 11010 TXT 6511 MC G - Dish spice Nove f i lee NANCY IAN 1139 AIC N - extended li, / - Sort dir 1115114864 IASIC

NANCY NOL 1137 AIC 1 - invoke pros - Sel Patter. F1-d

NANCY It 913 ARC L - Loy diskNir - Time I late 13 F2-l.

TEL8ASTY LET 127 ARC N - lode change . -Toe file It F3 -t,.

ÚTIL INI 16634 ARC F - Set path - - Unto, file 1 F1-ys

VT IL TXT 19172 ARC Q - spool Isere - List to, or F5 -sly

LIT L_AI Nr 19338 AIC maintenance unto, f i les ®1 F6-3ly I - lena.. file ESC-0401T KEY 17 LOC

S - Spool file IIGI - letsrn FB-1M T - filename to -- F9-L8 Tog hie

U - Unto, file application FI-ea I -QUIT Nove c. key rwr to hurt/ fil with arras keys a d pr... desired c miad

Fig. 21 -The Command Summary column on the screen lists the Fig. 22 -Best Friend's calculator pops -up in the lower functions available for file maneuvering by Best Friend. right corner. The FI Flo keys trigger scientific functions. time. Then there's a typewriter mode that makes your printer function almost the same as one of the new memory typewriters; and there's even an ASCII table mode, which is shown in Figs. 19 and 20.

If you need to know the ASCII codes that create the Se 93: regular ASCII characters, the cute faces, the international male and female symbols, musical notes, and even a small Monopoly house, you'll find their ASCII code in the first table (Fig. 19). If you need the ASCII codes for 1AS1 foreign characters, Greek and math symbols, even IBM FT-.' F2-l. graphics so you can used them in a word -processed docu- 13-1- F1-y' ment, you'll find them in the second ASCII table (Fig. r5-.4, 20). 16-Ny F7-L000 But Best Friend's real power is in disk -file manipula- 1e-1C 19-LN tion, as shown in Fig. 21. The functions shown in the r6-e ELP INF19+7. COMMAND SUMMARY column gives you a good idea I -QUIT of the extensive file manipulation that's available. There', even a Find File, which is similar to, but not as flexible as our old friend SFIND.COM. Fig. 23- Graphic paper -tape of Best Friend's calculator Figure It Out comes out of the top like a conventional desk -top job. Most unusual, and impressive, is Best Friend's calculator, which, as shown in Fig. 22, comes up in the lower a screen. The screen display closely right corner of blank .. I5zh Wiz resembles a small scientific calculator (note the scientific Custo.izatioalnstal lotion Program functions on the F1 F10 keys). As shown in Fig. 23, a Set Disk Wiz Special Print Code Nenn flows out the top, much as it would from "paper tape," The original Disk Wit Printer Cole Men, is pre- i.itializd for a. Epson a conventional calculator having a built -in paper -tape or code coplihle printer This Mery is displayed Gelas, .plated with each nos entry yu make to change asy item on it printer. In the illustration, the "tape" shows both multipli- I name Coles Coles I Name Codes cation (at the top -indicated by the * symbol) and addi- 12,B,v8,8 27,87,1,1,1 r 2L73,I,V1 functions operate only within the cal- 2 27,61,8,8,8 15,27,63,14 C 27,73,14,1 tion. The scientific 7 27,52,8,1,8 27,88,27,81,1 N 27,65,12,27,51 1 27,53,8,11,8 culator's window, although answers are printed on the 27,69,8,8,1 I 27,65,9,27,56 S 15,8,8,8,8 27,784,84 3 27,65,5,27,56 6 27,98,8,1,8 "tape." 27.15í1/8,8 R Other 7 27,87,I,1,8 27,15,8,8,8

Tu changea Neu Disk Wiz L.try press the I for it or DISCI to Exit this Page'_ Another heavyweight, though A low -cost, utility program, is Disk Wiz, which is basically a memory- resident, kitchen -sink, file- transfer utility with the usual extras such as a typewriter mode, an ASCII chart, even a background color control. But my favorite part is direct output of printer - control commands while running any program-that's Fig. 24 -Disk Wiz programs 19 printer -control codes. A the biggie. 20th is a wide card that the user can compose when needed.

57 Drive Access R Utilities. VI. DB - Disk Wis - Disk SEEDEISV Verso. S A, Jul, 1987 Walker Memphis, c 1986 Coeputer Creations, 3538 Me., 111 38111 Correlation Systems codes: ((ESC) to exil/ if Ixhio Gorse Mad. Reecho Palos Verdes. Printer CA 98271 ,213, 831 -3st: d 9. :cpwryht 19N. 19K. 1987 1y Correlation I FF 5. Cd 1111Sd I IIIM N. Systems All 6 LPI Ibshts leier: ei 2 leset 6. Cd - 8. WS- E IDI - I. I LPI a a SeekEasy is user supported ) PILI 7. Lop I. Sep F Ital. J. Slip software ore eec d to distribute copies of Seeltasy 4 ILI - 8. Ex - C. imp - G. Ital- I. Other If you find SeelEasv sefwl. PLEASE SUPPORT IT by reyistersns Code?:_ Send $38 N. your name and address the disk (5 os for.at -1'4- or 3 -1'2 "I to Correlation Systems Calif customers .3. tales :ac VISA/MC 0 L - send card number. eupiration dte. and signature

If you use SeelEasy please resister holstered users receive a printed I. the most current ,.,iteited copy of SeeIEesy. telephone support for Seeklsy, and proept notificatiee of epgrdes See the SEEKIEAD ME file for more information.

Oriel instructions Si I od somethise. Just type it (close is usually good esos b) them press [NM ! -mss ESCAPE novice/ for Mode Select. or press CONTAOL-I (trice/ to Vitt

Fig. 25-Once the codes are entered into Disk Wiz, the Fig. 26 -For a fee Seekeasy otters registration, printed screen will display only the functions, not the codes. manual, recent version, telephone support. and upgrades.

As shown in Fig. 24, Disk Wiz allows 19 printer - control codes to be user -programmed. A 20th position is a wild card that the user can compose when needed. As you can see, the program comes configured for the 34 P5 I SEEIEA.t .. most commonly used Epson printer codes, but the user eurth Results

Ee'IMRI)A A POWERFUL ALGORITHMIC ENCORING TECHNIQUE can set them for any function for any printer, and any EMPLOYED IN THE CALATI),

MANUALS - haply Dictionary') function can accept up to five control codes. Of CORNIER The 2.8 ICI CACE IS TO SEE WHAT LVEMO8E [LSE HAS SEEN MI Once the codes are. entered via a THINK WHAT NO ONE ELSE HAS configuration pro- THOUGR - Albert Ssent- Gyorgyi gram, the printer -control operating screen will appear TMC DI IIGENCC ILTNCEN GENIUS AND STUPIDITY IS THAT GENIUS HAS ITS LIMITS - as shown in Fig. 25. Notice that only the functions, not a.A.

PATIENCE MAD TIME DO MORE their actual codes are displayed. Also notice that the func- THAN STRENGTH 01 PASSION - Jun Dr La Fontaine

IF FATE SENDS YOU A LEMON, USE IT TO tions in Fig. 25 are not the same as the functions shown MAKE LQIOHIE - Lawrence (loch in Fig. 24. I have changed several Epson codes to IBM Type what you wish to find, then p ENTER Press Just ENTER to display up printer lc 188 is Press codes. For example, the Epson codes D and E ESCAPE (twice? for Mode Select, CONTROL-E (twice: to edit or delete uy items shown in Fig. 24 have been changed in Fig. 25 to turn above. CONTROL-T for hardcopy, CONTROL-8 (twice: to 'wit on my printer's IBM graphics character emulation. Like- wise, the Epson J code, which provides 14 lines per inch, has been changed so my IBM printer will do a Skip (perfo- ration skip) when listing BASIC programs.

Fig. 27 -By inputting the letters "ENCRY," Seekeasy sought How to Do It what the user was looking for. Seekeasy provided the five quotes. To send a code to a the printer you simply enter the appropriate number or letter in response to the screen or by direct copy from users. As shown in Fig. 26 (Seekeasy's cue "Code." You can enter several codes, because the opening display) the user is informed that for a modest screen cue appears after each code is selected. When the fee he can register to obtain a printed manual, get the ENTER Of RETURN key is pressed all the codes are immedi- most -recent version of the program, telephone support, ately sent to the printer, even if you're running a program. and notification of upgrades. For example, let's assume your word processor makes Seekeasy creates a database that is really limited only no provision for easily entering an italics or microtype by the capacity of the disk system. Each entry consists printer code; no problem! At the point in the text that you of two lines of randomly entered information. To locate want to switch to italics you embed the STOP PRINT command any data the user simply keyboards whatever he or she in the text, use Disk Wiz to send the italics printer code, can remember. In just a few seconds -and I have never resume printing (which will be in italics), have the printer taken more than 10 seconds regardless of the type or size stop when you want to return to standard printing, and of my disk system or database -Seekeasy will dig out all z use Disk Wiz to a RESET o send printer control code. Or, you the data that has any resemblance to the entered search rz could send a microtype code, even combine several codes, characters. such as bold /italics (Near w /NLQ Letter Quality). For example, I have a database of quotations I occasion- ally like to use in letters, speeches, and even articles.

Find Anything I ó Recently, needed something on encryption, which I knew ch Finally, we come to an unusually powerful shareware was in the database, but I had no idea how it was filed. database Seekeasy. To refresh á utility called your mem- So as shown in Fig. 27, I simply keyboarded the letters x ory, shareware is provided free of charge on bulletin boards (Continued on page 92) 58 By W. Schopp `CIi00SI1YG it the RIGHT LOGIC CHIP The chips are stacked against you if you don't understand the difference in the capabilities of various logic IC groups!

ften, when putting together some contraption from a ment. Speed is traded off for less power consumption and the magazine article, or an electronics -hobby project various trade -offs that resulted were regular TTL, high -speed O hook, it's difficult to determine if you're using the TTL, and low -power TTL. right component: For instance, the circuit might call for an Then along came the Schottky devices which added Schot- inverter at a particular point. Simple....any 'ol inverter will tky TTL, low -power Schottky TTL, and advanced low -power do, right? Wrong! Haven't you ever wondered why there are Schottky TTL to the groups. Schottky devices are faster than so many different inverters available? Well it's because dif- regular TTL, and require far less power. Speed is one of the ferent inverters have various capabilities; for example, one specifications used to subdivide chips. might be a high -speed type, while another might be endowed with low -power capabilities. Operating Speed Those cryptic code letters on integrated circuits are impor- The speed of a gate is defined as the propagation time. tant; and if they are ignored, you could have some very Simply stated, it is the time that it takes for the output to unpleasant surprises. For instance, take this scenario: You've change after the input has changed. That time is designated in finally finished designing your whatsit and now you're ready nanoseconds. (A nanosecond is defined as one billionth of a to build it. The next step is to select the chips that you are second.) going to use. You pick up your chip catalog and there are a Admittedly, a nanosecond is a very short period, but it is half a dozen versions for every chip you need. still the factor that limits the upper operating frequency of the Do you pick the one that costs the least, or the one that has particular chip. The power capability of the chip determines the highest speed? Or maybe you should use CMOS. Select- how many other gate inputs can be tied to one gate output ing the correct chip type for your particular application is a without drawing excessive current. If too many gates are tied decision that can only be made logically if you know the to one output, the output will drop below a usable value. advantages and limitations of the various types. It also determines the final power -supply current required for the particular circuit, which could be an important factor Different Strokes in your design criteria. The term used for describing how "Ihc two largest TTL families -and often the easiest to many inputs can be tied to the output of a single gate is called obtain -are the 5400 and 7400 types. There are over two the fan -out. Low-power TTL chips are not capable of driving hundred and fifty different chips in each of those families. more than one high -power chip reliably, and are limited to The main difference in the two families are their specified driving only two regular TTL logic inputs. It can be seen that operating -temperature range. For the 5400 type, the operat- the designer can receive some nasty surprises when logic - ing- temperature range is specified as 0 degrees to 70 degrees chip types are mixed. centigrade. The specified temperature range for the 7400 type The CMOS family usually does not present any problems is -55 degrees to 125 degrees centigrade. Both types are with fan -outs as long as they are fanned out to other CMOS usually well within the temperature limits of any equipment inputs. The rule of thumb is no more than 50 CMOS inputs the experimenter might build, so the choice between the two tied to one CMOS output. Since CMOS logic operates quite families may not be an important factor. well at the same voltage as TTL logic, and since some logic Now that we have distinguished between the two main functions are only available on one type or the other, it is families, we see that they are subdivided into more groups, inevitable that the logic types will eventually be mixed in the which are classified by speed and power ratings. With TTL, same circuit. increasing the speed results in an increased current require- Problems can arise when mixing the two logic types if the 59 fan -out limits arc not observed. The fan -out capabilities of often capable of frequencies of better than 50 -MHz. A little various chip types are given in Table I. The table allows you more care must be taken in using CMOS "A "- series chips to determine how many inputs of one chip type you can drive over TTL, but it is not beyond the capabilities of the beginner. with the output from another type of chip. If you live in an area where the air is extremely dry, static The frequency range of the CMOS is quite adequate for charges can be developed that will destroy the chip by just many applications. and power requirements make it ideal picking it up. Your particular geographical area may require where minimum battery current drain is required. There are you to use grounded wrist-straps and floor pads when work- two different series of CMOS logic chips (designated by an ing with the "A" series chip. That problem has largely been "A" or "B" after the part number). and a recently developed eliminated by buffering in the "B" series. high -speed type. Now that we have briefly covered some of the good and bad The A and B types are identical in operation. but do have a features about the different types, learning how to read the subtle difference. The "A" following the part number indi- various designations seem to be the next order of business. cates that that particular chip is not buffered. They can cause some abominable problems (which we won't go into at this Reading the Markings time). Needless to say. the "B" type is a better choice and it is When we are looking at TTL chips, the first two numbers hoped that one day, all of the CMOS chips will be of the "B" (54 or 74) designates the chip series. The letter or letters type. following the series number indicate the sub-family. The The "B" type has a buffered output, improving its letter H stands for hi- speed. The letter L indicates low -power risetime, while making the output drive between the various while S means that the chip is a regular Schottky device. The chips identical. The third type is constructed using silicon on letters LS stand for low-power Schottky, while ALS means sapphire, which improves the propagation time. They are advanced low-power Schottky. There are others, but those types cover most circuit requirements. TABLE 1- FAN -OUT TTL CHIPS COMPARISONS The numbers following the letters indicate the type function of the chip. At Outpid Regular Low -Power High -Speec Schottky Low -Power TTL TTL TTL Schottky the last count, those numbers started at From: TTL Inputs Inputs Inputs Inputs Inputs Inputs 00 and ran as high as 670 with a lot of Regular numbers missing between them. If the 10 40 6 6 20 50 TTL numbers follow the series number 17 with- Low -Power out any letters, it designates a regular or 2 10 1 1 5 50 TTL standard TTL chip. Any letters follow- High -Speed ing the function numbers pertain to the 12 40 10 10 40 50 TTL package type and /or military specifica- Schottky tions. Those designations are not that 12 40 10 10 40 50 TTL important for the beginner, since the Low -Power plastic encapsulations (that we've 5 20 4 4 10 50 Schottky TTL grown used to) always cost less than the

CMOS '/2 ' 1/2 1 1 50 ceramic version of the same chip. High -Speed Choosing the correct chip for your 2 10 1 1 CMOS 5 50 own particular application is just a matter of determining your frequency and 'Two gates can be paralled to drive 1 input. power requirements. Table 2 compares TABLE TYPICAL 2- VALUES FOR TTL CHIPS CORE PARISONS the speeds and power ratings of the vari- Propagation Series Output Gate Freq. Operating ous integrated- circuit chip types. That Time Tye Number Current Input Range Voltage chart can help to determine which chip (Nanoseconds) (mA) Current (MHz) (VDC) I to use in your design. It's obvious that a Regular 5400 10 16 high -speed TTL chip works well in a TTL 7400 1.6 µA 35 5 low -speed circuit, but a slower chip may LowPower 54L00 33 not perform in a circuit that calls for TTL 74L00 3.6 .18 µA 3 5 high -frequency response. High -Speed 54H00 You wouldn't want to use high -speed TTL 74H00 6 20 2µA 50 5 TTL logic with its high -current require- Regular 54S00 ments to design a low- frequency circuit Schottky 74S00 3 20 2µA 120 5 that will operate for months on a small Low -Power 54LS00 10 battery. You will also want to avoid fan- Schottky 74LS00 8 .4 µA 45 5 ning too many gates from a low-power Advanced 54ALSOO output. Those are only a few of the Low -Power 5 4 20 µA 5 74ALSOO 30 1 pitfalls that can be avoided you're Schottky -and sure to run into others. Knowing the CD4000 60 .8 5 pA 5 5 CMOS various chip variations can help you MC14000 25 2 15 pA 15 15 pick the right chip and, we hope, avoid High -Speed 74HC4000 the design problems before they hap- 8 8 1 µA 30 -50 2 -6 1 CMOS pen.

60 111111/111111t+f SIM 11111/1111111111111111111111111ti/ 1111111iti1111111111ti61ttil

Calculator A Handy Pop-Up Calculator for Basic Mathematical Functions Byte Sizé ,. .r. A SOFTWARE 4nwv,re//////// k,.,xtn Irnvmart.,nal. : 1 STUDIOS ...... BYTESIZE CALCULATOR

A handy, memory- resident, pop -up, calculator program for basic mathematical applications on IBM and MS -DOS machines

CIRCLE 75 ON FREE INFORMATION CARD

a or the DONE DAY I WANTED TO CHECK MATH ifornia for introducing the ByteSize Cal- Calculator is inserted into drive the accounting department used to waste culator. The program provides an on- program has been copied to a hard disk, my salary. In particular, I wanted to sum screen calculator that is a full- function, type CALC (CALC B for monochrome the deductions and subtract them from the printing calculator with memory display screens) at the DOS prompt (A:, etc.) total gross income. Simple? I thought so and no high -order math settings. Its fea- ByteSize Calculator is now on the screen. and as I picked up a pocket calculator from an tures include: add, subtract, multiply, and Press any key to get past the title plate engineer's desk. I couldn't sum two plus divide; add to, or subtract from, displayed you're ready to run ByteSize Calculator. two to ring up four. My engineer friend memory; square root; make a printed tape said that the calculator was a programma- of calculations; and display results in ev- Memory Resident ble type set to operate on Laplace trans- eryday decimals or hex, binary, or octal Loading ByteSize Calculator as a forms for four -dimensional vector analy- notation. memory- resident program requires 49K sis. I ended up in the accounting The software is designed to be an alter- of RAM -a very small price to pay. Other and department using a vintage 1965 adding native to expensive, difficult to learn, and programs can be loaded in memory machine with tape readout. That was more often difficult to use, programs. ByteSize run while the software lies dormant in my speed. Calculator can run as a stand -alone pro- memory, but it is executable at any time When calculators were first introduced, gram or it may be accessed as memory- even from within another program. they were basically adding-machine types resident and thus, pop -up when needed, To load ByteSize Calculator into with almost no frills. Today, a pocket - even when another application is being RAM, type CALC R (with a monochrome calculator operator has to keep the manual run. screen type CALC B R) and press ENTER. handy because of the many add -on fea- To bring Calculator to the screen type Aix- tures. The features came about during the Getting Started K. When the title screen appears, press past two decades, because of the state -of- All you require is a machine that is an any key -you're up and running! the -art improvements and marketing tech- IBM PC, XT, AT, or MS -DOS compati- niques demanded more and more features ble computer that uses either IBM DOS or Using the Calculator as the price fell through the floor. MS -DOS. It'll work with a one 5 -1/4-in. If you know an thing about cal- Thus the scene was set for calculator disk -drive system, or two disk drives, or culators, you can start experimenting with software for personal computers. A host one disk drive with a multi- megabyte ByteSize Calculator once the program is of calculator programs popped-up in the hard -disk drive. Copy ByteSize Cal- on the screen. The operands are + -, *. /, last ten years that could count the spots on culator onto a diskette and store the origi- M, S. and SQ which stand for add, minus. memory, subtract a newt as it Laplaced my transform. nal diskette in a safe, storage bin at room multiply, divide, add to Sometimes, the simple things are what we temperature. It's a good idea to write - from memory, and square root. It does not need and you can't find them. protect the original. matter where the operand is placed. For My thanks to Software Studios in Cal- After a diskette containing ByteSize example, typing *8 and ENTER or 8* and

61 Here's what you see on the monitor's .:9.ii0+ screen (left) after adding 39 and subtracting 7, multiplying by 8. -7. i t:- dividing 4. and taking the square

8 . 00 * root. Imagine what you see is a paper 4.11(1/ tape spooling from an office -type, desk -top calculator. The listings at S C? the top indicate the numbers keyboarded and the operand in effect to the right. The total appears near the bottom. At the very bottom of the tape are prompts that you need to operate ByteSize Calculator. In fact, once the program is on the screen, you can toss away the owner's manual. The first prompt shown is Dfi which sets the number of decimal places. You can select any value from 0 to 9; the default is 2 assuming that most 8. Ou additions will be for dollar values. Should you want a printout of your calculations. the P key toggles the Set < ;: D11 >ec i mal printer in and out. Where the decimal Set ec lea l <:C; >lear Entry setting indication was previously. (Meer tetry there now appears THE emory+ Memor y - either PRINTER (Memory; (Memo Recall Memory IS ON or THE PRINTER IS OFF toggle information. At right is a DOS Clear Memory printout using the SHIFT and Parse Clear Memory otal <::F':: :.rinter keys. For more information on ByteSize Calculator No. 75 otal «>rteter ::ALT: +K Blink In /Out circle on the Free Information Card. (ALT)+11 lliek le/Ont

EN I ER will have the sanie el teet -the pre- the ESC key when operated as a stand- (suggested retail price). Mail orders vious total will be multiplied by 8. If no alone program. If Calculator is memory- should be sent to Software Studios, 8516 operand is used, the previous operand is resident, press the ALT and K keys simulta- Sugarbush, Suite 104, Annandale, VA used. If there is no previous operand neously to exit the program. Pressing the 22003. Include $5.00 for shipping costs. (when first starting or after a total), addi- ESC key will purge the resident -memory Software Studios can be reached by tele- tion is assumed. program from RAM. In some programs phone: 703/978 -23239. For more infor- To add the total on the screen to the you will not be able to use the Esc key to mation via Hands -on Electronics, circle Calculator's memory, press the M key and rid the resident memory or Calculator di- No. 75 on the Free Information Card. then the ENTER key. To subtract, use the S rectly. A message will come up which and ENTER keys. To recall the number in reads, "CANNOT EXIT NOW." Appar- memory, type RM and ENTER. To clear ently, that is a blocking device that pre- memory, type CM and ENTER. vents loss of resident memory to other To repeat an entry, press ENTER. To stored programs or the introduction of a clear the calculations, press C and ENTER. disastrous glitch. You must return to the To clear the current entry, press C and E DOS prompt to remove ByteSize Cal- and then ENTER. To take the square root of culator from RAM. the total, type SQ and then ENTER. One unusual feature is the opportunity Putting It to Work to display the total in notation other than I he last few paragraphs are all you need decimal. To read out in hexadecimal, oc- to know to successfully operate ByteSize tal or binary, press H, D, or B, respec- Calculator -you can throw away the user tively. you have no If need to use that manual in CALC.DOC, because you now +11VUUV11pVV1100VV11 feature, ignore it. Some software pro- know it all. If you set up your path state- grammers will find that they will be living ments correctly, pressing the ALT and K Set lear CE Entry and out. If you don't know how to set up a emory+ ~~Memory- Recall Memory Print Out sub -directory and path statements, refer to Clear Memory You can have your printer provide a the user's manual. Follow the directions otal~~

rinter hard readout for your calculations up -to- and then cast the manual aside. ape Program the- minute each time you press the ENTER After the first time into the program, key. To toggle the printer on and off, press the title screen will not reappear and the the P and ENTER keys. That option prints program goes direct to the image of the One of the features of ByteSize Calc each entry as the ENTER key is pressed. In calculator's tape. Part of the tape image ulator is the ability to obtain binary. hex. and octal numbers from order to get a print -out total, press T and contains a prompt -key directory, hereby a decimal numbers. The screen print- ENTER. You can also press the SHIFT and clever operator can surmise the operating out shows the decimal number 399.555 Purse keys at the same time. The unused procedure without further reference to the converted to an eleven -place binary portions of the screen display will print user manual. number. Check the results using pen- out zeros. ByteSize Calculator is available from cil and paper. You'll get to appre To get out of ByteSize Calculator press computer and software outlets for $19.95 ciate this time -saving feature.

62 DEVERY RADIO AND RADAR TECHNICIAN WANTS TO OWN A Second Class FCC General Radiotelephone Operator Li- cense; a First Class license would be all right, too. Just GETTING YOUR mention the very title to a tech (with or without class distinc- tion) and watch his eyes roll, and then listen as he talks about his potential for increased earnings if he had it. Oh yes, even FCC LICENSE today with technical school diplomas, associate degrees from junior colleges, and even engineering degrees from the big institutions, all electronic wizards dream of holding an FCC Here's everything you need to pass license. Apparently the prestige, the mystique, and the pride the FCC examination and get your who the test to receive the coveted still ring true for those pass FCC General Radiotelephone Operator FCC General Radiotelephone Operator License (GROL). Every tech, at one time or another, has the experience of License going to some social event or gathering, meeting other electronic enthusiasts, and pretty soon the conversation comes By Jon Gordon around to the question, "Gee, do you have your FCC license?" Wouldn't it be great to say, "Sure I have it." Then the guy smiles broadly, because everyone recognizes the FCC need the GROL license to certify that the equipment you test ticket as the very top; moreover, when you get your license and install does indeed meet the FCC standards for emission you're automatically accepted as someone who know his type, power output, carrier frequency tolerance, etc. Without stuff. the GROL license you are not qualified to make such a determination. (That's an interesting point -you are not Climbing the Ladder qualified even though you may be very knowledgeable and In today's increasingly competitive job market every proficient.) feather in your cap is to your own benefit. The FCC license carries with it government certification saying you are recog- Getting Started nized as legally and technically competent to install, main- Changes in technology and FCC rules have made previous tain and repair marine, land mobile, aviation and public radio examinations for the Commission's General Radiotelephone stations. It's this legal authorization and government stamp of Operator License obsolete. As a result, the commission has approval that sets the FCC license apart from all other tech- revised all future GROL examinations to include certain nical certificates. marine radio subjects and omit outdated questions. There are many obstacles to overcome on your way to Preparation for the GROL examination should include passing the FCC test. As someone who just passed the review of materials contained in commercially available GROL, I'm going to tell you my secrets (that is, hard work study guides. The FCC does not certify schools or review and dedication) so you too can pass the examination. Every- study manuals. Consequently, the FCC will not recommend a thing you need to know to get started on that road to success, particular school or publication. The review material should I've put down on the following pages. All the little frustrating include information that covers both the GROL and the mistakes that discourage so many techs and prevent them Marine Radio Operator Permit. Anyone who uses prepara- from reaching their goal, you can now breeze right through. tion materials provided by any FCC Field Office should study The study materials you will need, the FCC rules and regula- both Bulletins FO -32 and FO -33. The commercial license tions, the different types of test questions you will encounter, examination policy is outlined in Bulletin FO -4, and the FCC and finally taking and passing the examination. I will walk examination schedule is also available upon request. you through it all so that you'll know what to expect in the examination room and can be better prepared to pass the FCC Study Manuals examination. Adequate preparation for any examination is the key to passing. There are several commercially available study GROL Requirements guides, and since the study guide will be your main focal The General Radiotelephone Operator License is required point to success, it's important to select the one that's right for for persons responsible for internal repairs, maintenance, and you. Walk into any large book store or library and at least one adjustment of FCC -licensed radiotelephone transmitters in or maybe two different study guides will be on display. If you the Aviation, Maritime, and International Fixed Public -Ra- have the opportunity to compare them you'll find they're dio Services. It is also required for the operation of Maritime organized differently and the scope and depth of technical Land Radio transmitters operating with more than 1500 -watts information contained in them will vary widely. I visited a peak -envelope power, and Maritime Mobile Ship and Aero- shopping mall and checked out two book stores. Between nautical transmitters with more than 1000 -watts of peak - those stores and the public library I selected Milton Ka- envelope power. The GROL is normally valid for the lifetime ufman's: Radio Operator's License Q & A Manual, Tenth of the operator. Edition. To be eligible for this license, you must: 1 be a legal My reasons for selecting Kaufman's manual were many resident of (eligible for employment in) the United States; 2 fold. First, there seems to be much more in -depth technical be able to receive and transmit spoken messages in English; information then in the other books I have seen on the same and 3 pass a written examination covering basic radio law, topic, and the author included a lot of schematic diagrams for operating procedures, and basic electronics. illustrating his technical points. For example, let's say you want to repair and maintain two - For most of the FCC topic questions he had a straighttor- way communications equipment in the aviation industry. You ward answer and then elaborated further with a technical 65 This is the study guide I used to pass 'the GROL. There are several other RA010 guides available, you be the judge as to what's best for you. You can get this one OPERATOR' from Hayden Books, 4300 West 62nd Street, Indianapolis, IN 46258, Book No. LICENSE 040666. Tel. 800 428 -3602. 516.95.

~~MANUALran HMI bu,O1M WIIMINppYO!NYC. 1.111101, 1AYMIR("I"M~~

~~FCC recommended the Marine Radiotelephone is available from Radio Technical Commission for Maritime Service, P.O. Box 19087, Washington, DC 20036, S7.95.~~

discussion. I found the learning approach to be the easiest for The Bulletins me to understand and follow. I also found the technical FCC Bulletin FO -33, January 1987, has all the information discussion to be helpful as background information, so that I you will need in order to answer questions encompassing could better understand other reference sources that I have. elements I and 2. According to the FCC, elements I and 2 The FCC rules and regulations for the GROL examination require knowledge of the following: Marine Radiotelephone may contain as many as 15 to 20 R & R questions alone. Operator Permit; basic marine radio law and basic marine Kaufman takes the confusion out of the new FCC license radio operating practice. Provisions of laws, treaties and structure with a book preface of the most commonly asked regulations with which every radio operator in the maritime questions, and of course he supplies the answers. The Q & A radio services should be familiar. Radio operating procedures manual has a number of other useful items like a list of FCC Field Offices and their addresses, a guide to troubleshooting and analyzing FCC exam -type circuits, and a complete FCC TABLE 1 -FCC FIELD OFFICES AND PHONE NUMBERS sample examination. Lastly, the 531 page manual is in its Office Number tenth edition, and I figured any book in its tenth edition must be doing something right. I will further review Milton Ka- ALASKA, Anchorage 907/243 -2153 ARIZONA, Douglas 602/364 -8414 ufman's Q & A Manual as the article continues. CALIFORNIA, San Diego 619/293 -5478 CALIFORNIA, Livermore 415/447 -3614 Radiotelephone Handbook CALIFORNIA, Long Beach 213/426 -4451 The FCC recommends that you obtain the Marine Radi- CALIFORNIA, San Francisco 415/556 -7701 COLORADO, otelephone Users Handbook. The text explains and describes Denver 303/236 -8026 FLORIDA, Ft. Lauderdale 305/473 -9845 in detail the proper readiotelephone operating procedures and FLORIDA, Miami 305/350 -5542 also contains a complete list of the VHF Marine Channels, GEORGIA, Atlanta 404/347 -3084 U.S. Coast Guard Stations.and Public Coast Stations. This is GEORGIA, Powder Springs 404/943 -5420 a great little book and gives you all the marine VHF Channel HAWAII, Walpahu 808/677 -3318 ILLINOIS, Chicago 312/353 -0195 frequencies and their uses; it's loaded with radio operating LOUISIANA, New Orleans 504/589 -2095 procedures like how to make a distress call, how to place a MAINE, Belfast 207/338 -4088 ship to shore telephone call, and procedures for calling ship MARYLAND, Baltimore 301/962 -2728 to ship, etc. Anyone who owns a pleasure boat should have MARYLAND, Columbia 301/725-3474 this handbook. MASSACHUSETTS, Boston 617/223 -6609 MICHIGAN, Allegan 616/673 -2063 MICHIGAN, Farmington Hills 313/226 -6078 Getting Information MINNESOTA, St. Paul 612/725 -7810 When you call the FCC Field Office, ask for the General MISSOURI, Kansas 816/926 -5111 Class Exam Application Form 756 and Exam Schedule, also NEBRASKA, Grand Island 308/382 -4296 NEW YORK, Buffalo 716/846 -4511 ask for Bulletins FO -32, FO -33, FO -4 and any public notices NEW YORK, New York 212/620 -3437 concerning the GROL. There is no fee for any of the FCC OREGON, Portland 503/221 -4114 bulletins or forms, and there is no GROL application fee. PENNSYLVANIA, Philadelphia 215/752 -1323 Form 756 can also be used to apply for a renewal when PUERTO RICO, San Juan 809/753 -4567 TEXAS, Dallas 214/767 -5690 necessary, replacement of a lost or mutilated license, and for TEXAS, Houston 713- 229 -2748 a verification card, when necessary. TEXAS, Kingsville 512/592 -2531 Typical examination dates vary slightly from year to year. VIRGINIA, Norfolk 804/441 -6472 Contact the FCC Field Office nearest you for an official WASHINGTON, Ferndale 206/354 -4892 schedule. WASHINGTON, Seattle 206/764 -3324

66 and practices generally followed or required in communicat- answer since the question only asks about DC current. and an ing by radiotelephone in the maritime radio services. ampere meter measures only DC current. FCC Bulletin FO -32, April 1983. is slightly outdated but As you can see you have to watch out for trick questions it's all the FCC has to offer. It's just a list of study questions which have more than one right answer; you are then required without answers, and they're identical to the study questions to select the best answer or the most correct answer. Another with answers in Kaufman's Q & A Manual. According to the trick question is where all the answers seem wrong and you FCC, element 3 requires knowledge of the following: Gener- have to select the one that appears most nearly correct. Those al Radiotelephone, all of elements I and 2 stated above plus can drive you crazy. Your best defense against trick questions technical matters including fundamentals of electronics tech- is a thorough knowledge of the facts. nology, and maintenance techniques as necessary for repair Many of the test questions require a mathematical answer. and maintenance of radio transmitters and receivers. at least you can then calculate a precise number. But watch out, they'll trick you in the way the question is worded or the More Stuff way the schematic is drawn. Very often I'll redraw the given If your electronic tech skills are a bit rusty or you're really schematic into a form which is more familiar to me. Take for starting from scratch and would like additional study mate- example test question, Q2 following; I'd redraw Fig. IA into rial, then try Command Productions. FCC License Training, schematic Fig. 1B which looks easier to solve. That sometime Dept. 90, P.O. Box 2223, San Francisco, CA 94126. $169.95 takes a considerable amount of time, but if you get the right They advertise in Radio Electronics magazine all the time. I answer then it's well worth the effort. Since there's no exam- sent them a request for more information on their product and ination time limit, you can take as long as you like to I received a well organized brochure which described their complete the test. FCC study approach. It included teaching audio tapes, sample FCC test questions, and a large study manual with a CI problems. separate pamphlet for calculating FCC -type math X xo The brochure looks good. If you can afford it and you are well motivated, then it might be worth your while. C2 Lastly, in Table I we include a list of FCC Field Offices and 2 c2 C4 phone numbers to help you get started. If you don't live 1 c4 their 1 1 near one that's listed, then you've got a problem. Some C3 people end up with a long plane ride and expensive hotel T 43 accommodations. Y Test Questions A B FCC questions are the multiple- choice type, none All Q2: What is the total capacitance between points X and Y? require a written, essay, or verbal response. You might think a. 1.43 p.F that multiple- choice questions are usually the easiest to an- b. 0.70 µF swer; but you can be sure that the FCC is not going to make c. 2.1 p.F your life easy while your sweating -out their test questions. d. 8.0 RF Every question has 5 possible answers labeled a,b, c, d, and e. 6.0 p F e. The questions themselves are usually straightforward, but the answers are typically thought -provoking and downright The correct answer to Q2 is b, 0.7 RF. Capacitor C4 is tricky. The correct answer is never so obvious that it appears drawn on a slant to confuse you. Towards the end of the test to jump right out of the page, tap you on the shoulder and say, after three hours have passed and you're getting tired, you lunch. That's when they'll "Here 1 am." I was surprised because I was depending on at want to finish up and break for least five or so give -me questions to help me through the test, throw a schematic like that in question Q2 at you, and but there really were no easy questions. It seemed that every because you're tired you'll rush through it and get it wrong. question had answers with curve balls thrown in, and believe Don't fall into that trap. If you find yourself rushing through me they were hard to hit. Take for example test question QI, a the questions, stop for a few seconds and take a deep breath seemingly easy question: and stretch your arms out, that may help you get a second wind, so to speak. What do you measure DC current with?

a. VOM R1 R1 b. DMM 1552 1552 c. VTVM d. Current Probe 01 02 30V 30V R2 e. Ampere Meter i 3052 R2 R3 Obviously you know that a VOM can measure DC current. I 3052 5012 I and so can a VTVM; those are usually multi -meters which voltage, current, ohms, etc. so answers a, b. and can measure A B c seem possible. Answer d current probe usually needs to be connected to some kind of meter which they don't mention. Q3. Find the approximate voltage drop across RI. I've used a current probe to measure really heavy currents in a a. 15 volts thick wire by sensing the strength of the self induced magnet- b. 20 volts ic field generated around the wire. Answer e is the best c. 10 volts 67 d. 5 volts 2 x IF+ Incoming frequency = 121.4 MHz. e. None of the above You can check that by subtracting the image frequency from The correct answer to Q3 is c, IO volts. It's plain to see in the the LO: test question they're trying to test your knowledge about 121.4 MHz-110.7 MHz = 10.7MHz diodes and voltage divider circuits. Diode, D2, is reverse biased and can be considered an open circuit; while diode, and the IF frequency is the same. DI, is forward biased and, since the question asks for an In Kaufman's Q & A manual he provides a typical FCC approximate voltage, we'll consider it a short circuit. Nor- practice examination which is structured to cover all the vital mally the forward voltage drop across a silicon diode is about topics of each element. The test questions are geared to the 0.7 volts. The given schematic in Fig. 2A can be redrafted text so if you're confused, you can turn back and review the into the schematic in Fig. IB which is a simple voltage material, then try the test question again. The practice exam divider circuit. One you could probably solve with your eyes questions are excellent and I wish there were more of them. closed. Very often I would think I knew a topic until I was quizzed, then I'd realize I needed more review.

Extra Q &A's While using the manual as a study guide you'll find that after the required FCC Q &A's is a section where additional Q &A's and new material has been added. As Kaufman puts it, the added material has been included to acquaint students RATIO DISCRIMINATOR with the current state of the electronics art. It is felt that the added material contains subject matter that may be required of students who have obtained a GROL and are seeking employment. AUDI[) AMP Additionally, the added material contains valuable infor- ( mation for future reference. He goes on to say that the new "added" questions do not in Q4: A standard FM broadcast receiver is tuned to 100MHz, appear any current FCC docu- ment. However, the general the local oscillator frequency is above the incoming signal, topics for the questions do appear in an FCC what is the image frequency? topical outline (not yet officially in force). a. 121.4 MHz I personally found that the added material was vital in b. 110.7 MHz passing the exam. The FCC has not officially said, for example, that c. 100 MHz you need to know op -amps, but, you better know d. 10.7 MHz them because they were on my test and were also in Ka- e. 20.4 MHz ufman's added Q &A's. Another such exam question I had was on varactors. A varactor is a diode that acts as a variable A superheterodyne receiver is subject to image inter- capacitor. It is normally reversed biased creating a capaci- ference. FM broadcast receivers have an IF (intermediate tance that varies with applied voltage and is used as a tuning frequency) of 10.7 MHz. Although this information is not element in, for example, TV sets using varactor tuning. The given, you're expected to know that to answer the question. FCC does not require you to know varactors according to There are two frequencies that will give the same IF dif- their outdated exam study guide Bulletin FO -32, however, ference frequency for a given local oscillator frequency, these Kaufman in his added Q &A sections addressed varactors and are, one lower and one higher than the local oscillator. The many other types of present -day diodes. In fact I can honestly LO (local oscillator) is given as above the incoming frequen- say that Kaufman's added Q &A's were as equally important cy which means the LO equals 110.7 MHz. The image as the FCC -required questions and answers to pass the exam. frequency in this case equals: Tubes Too The FCC has certainly updated their examinations, and Col At (- UN, i tNE Kaufman has kept up. How about another example? I worked UNITED STATES OF AMERICA really hard on electronic tube theory, like triodes, pentodes, I FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIOTELEPHONE and cold cathode voltage regulators, etc., but almost all my OPERATOR LICENSE (General Radiotelephone Certificate) questions were on transistors. The ironic part is the one tube question I did get was not from the required FCC topic EndWe.ment Neme questions, but, you guessed it, from Kaufman's additional JC) i,...f SNP Radar NÁlìIAN A. GI Q &A section. How many of you know what acquadag is? °aÖ015/54 08/03/87ät" Well, if you study Kaufman's manual you'll know and then L..: you too can pass the examination. Acquadag coating is on the Lü Othef Rr-y:n 524 forward portion of the CRT glass envelope and is electrically {See attachment! INVALID IF 'ACME connected to the accelerating anode potential. The acquadag THAN ONF BLU!. MARKED assists in the electron beam acceleration; and additionally, ÿF F C)VEr+: when secondary electrons bounce off the screen due to electron -beam bombardment, they are picked up by the acquadag Here's my pride and joy all nice and new before cutting. It may look like a small piece of paper, but it can help your career in a and returned to the power supply. big way. It may be worth your while. (Continued on page 90) 68 Scientific Notation and Unit Conversions By Louis E. Frenzel, Jr.

~~Tired of writing out zeros? Getting confused with milli, micro, kilo, meg, etc.? This month we'll clear it all up with powers.~~

['MOST OF THE ELECTRONICS MATH YOU WILL DO IS IN will constantly be working with very large and very small solving standard formulas with values related to your applica- numbers. tion. You will plug in the values, do the math, and arrive at Further, you will be converting the values from one unit to the data you require. The numerical values of the parameters another. That process is relatively easy when you use a math used in the formulas will be expressed in the appropriate basic technique known as scientific notation. In this article, we units such as volts, amperes, ohms, farads, henries, hertz, introduce you to scientific notation and show you how to use etc. Because of the very wide range of electronic values, you it in converting between units.

Scientific Notation they are much easier to deal with. Operations such as addi- In electronics, we work with very large and very small tion, subtraction, multiplication, and division are faster be- numbers and everything in between. For example, most satel- cause you are working with small values. The operations with lites transmit and receive on frequencies in the C band, 4 to 6 the powers of ten are separate from the other values. GHz ( gigahertz). A frequency of 6 GHz means 6,000,000,000 Hz or six billion hertz per second. Using such Working with Exponents a number in a formula is a problem. It takes time to write all A power of ten is the number ten with an exponent. The those zeros, and it is very easy to make a mistake. exponent, as you know, is the number at the upper right. All it Another example are capacitor values. Capacitor values really tells you is how many times to multiply ten by itself. are expressed in farads (F). A farad is a huge value, so most For example, 102 means to multiply two tens together, or capacitors have values only a fraction of that. A typical value 102 = 10x10 =100. might be 100 pF (picofarads) or .0000000001 F. Such decimal fractions are also a problem to work with for the same reasons The value of 105 is simply mentioned above. On top of that, keeping track of the deci- 10 x 10 x 10 x 10 x 10=100,000. mal point after a math operation is a nuisance. Another problem with such large and small numbers is that Table 1 shows all the values up to 101 °. Note the two special most ordinary calculators won't handle them. A typical cal- cases 10° and 10'. Any number with an exponent of zero is culator has an 8 -digit display. So, how do you enter or display simply I. A number with an exponent of 1 is just the number. a number with 9, 10 or more digits? So, 101 is simply 10. The solution to those problems is to use scientific notation. Scientific notation is just a special way of writing large and TABLE POWERS OF 10 small numbers. Any number is divided into two parts: 1- 1. A number between I and IO multiplied by 100 =1 2. A power of ten. 101 =10 Our frequency of 6 GHz or 6,000,000,000 would be ex- 102 =100 pressed as: 103 =1000 10° =10000 6 x 109 105 = 100000 106 = 1000000 Our capacitance of .0000000001 F would be expressed as: 107 = 10000000 108 = 100000000 1X10-10 100 = 1000000000 1010= 10000000000 Once numbers are expressed in scientific notation form, 69 The exponent also tells you where to put the decimal point. 3. Find the reciprocals of the following. In the expression 102, the 2 says to write two zeros after a I of a) 10-2= MO. The expression 105 says to write a I followed by 5 zeros. b) 106 Easy, huh? = c) 1/(5 x 10-3) = Negative Exponents d) 1/(4 x 107) _ There are also negative exponents such as 10-22. When you see a negative exponent, it means that the number is a fraction, or less than one. Remember, 100 is I. so when the Converting Standard to Scientific exponent goes negative, the value drops below one. A number in standard form looks like this: The expression I0-1 is the same as 1/101 or 1/10. Of course, 7,520,000 you can get the decimal value by dividing the numerator by the denomenator or I divided by 10, which is .1. If no decimal point is shown, it is assumed to be directly to the right of the right -most digit. TABLE 2- NEGATIVE POWERS OF 10 7,520,000.000

10-1 =1/10=.1 We can add zeros after the decimal point without affecting the 10-2 =1/100=.01 value. Now we want to put that number into scientific nota- 10-3 =1/1000=.001 tion. Here's what you do: 10-4 =1 /1 0000 = .0001 1. Convert the number to some value between I and 10 by 10-5 =1 /100000 = .00001 10-6 =1 /1000000 = .000001 moving the decimal point left, so that it is just to the right of 10-2 =1 /10000000 = .0000001 the left -most or most significant digit. 10-8 =1 /1 00000000 = .00000001 10-9 =1 1000000000 = .000000001 7.520000

10-10 =1 , 10000000000 = .0000000001 The number 7.52 is between 1 and 10. Note that you had to 1 0-1 1 =1 /100000000000 = .00000000001 10-12 = 1 /1000000000000 = .000000000001 move the decimal point over six places. 2. Multiply the number by the appropriate power of 10. The exponent is a number equal to the number of places you To remove the minus sign on the exponent, just divide I by the expression without the minus sign. Thus 10-2 is the sane moved the decimal point or:

as 1/102 1 or /100. Converting to decimal form you get .01. 7.52 x 106 Table 2 gives all the equivalent values through 10-122. There is one handy procedure you should learn. We can If you moved the decimal point to the left, the exponent is call it the reciprocal trick. The reciprocal of a number is just positive. This procedure the number divided into 1. The reciprocal of the number N is also works with decimal fractions. Take the I/N. The reciprocal of 2 is: value:

~~1/2 =.5 .000036~~

The reciprocal of the reciprocal of the number N is just N, or First, move the decimal point right to create a number between I and 10, or I /(1 /N) =N 00003.6 Using those relationships, you can simplify the handling of powers of ten. Here's how. Then multiply by the correct power of 10. Again, the number The reciprocal of a power of ten is just the power of ten with of places you moved the decimal point gives you the exponent the exponent sign changed. Here are some examples: value. 1/10; =I0-' 3.6 x 10-5 I /105= 105 In this case, since you moved the decimal point to the right. I/4 x 108=.25x 10 -8 the exponent is negative. 1/8 x 10-6= .125 x 106

Reciprocals are found in many electronic formulas. You can get rid of them with this trick. Practice Problems 4 and 5 OK, before we go on, try this yourself. Convert the following numbers to scientific notation:

Practice Problems 1 -3 4. 910,000,000 Just to be sure you've got the idea, work the practice 5. .00000000825 problems below. Do NOT look at Tables I and 2. 1. Convert the following expressions to their normal form: a) 103= Converting Back b) 10`'= Often you will need to go the other way, or change your scientific notation values back into standard form. It is pretty 2. Convert the following to decimal fractions: easy to do. Here's how. a) 10-6= 1. Look at the exponent and move the decimal point the b) 10 -12 = number of places indicated. 70 a) Move it left if the exponent is minus. multiplying by 10-2 (10-4 X 10-2 = 10-6). Now you have to b) Move it right if the exponent is positive. divide the numerical value by 10-2 to keep the total value the 2. Add zeros to the right or left as needed to fill the digit same. places. 2.9/10-2= 2.9/.01 = 290 For example: The new expression is 5.027 x 104 is 5.0270. or 50,270 290 x 10-6 Add any extra zeros on to the right if you need to. Here we Or, you could say, if you increase the numerical value of a added one. negative exponent by 2, you have to move the decimal point Another example: on the number 2 places to the right. The whole idea of this process is to change the decimal 1.9 x 10-5 is points location without changing the actual value represented .00001.9 or .000019 by the expression. Add as many zeros as needed. Another way to look at the procedure is just multiply the two parts of the expression. First, replace the power of 10 part Practice Problems 8 and 9 with its value from Tables 1 or 2, then multiply. Thus: Try these tor practice:

~~5.027 x 104= 8. 8.3 x 105 5.027 x 10000= 50270 Express the numerical part as a value between 100 and 1000. or 9. 1.5 x 10-5 1.9 x 10-5 = Express the exponent as 10-; 1.9 x .00001= .000019~~

Practice Problems 6 and 7 Doing Math Here's a couple more for you to try. Convert from scientific Now let's see how we can perform all the basic math notation to standard form. operations using numbers in scientific notation form. As it 6. 9.5 x 10' turns out, most operations will be either multiplication or 7. 3.303 x 10-9 division. Here's what you do: 1. Simply multiply or divide the numerical values as you normally would. 2. Then add or subtract the exponents to get the new correct Changing the Format power of 10. The standard way to present scientific notation numbers is a) Add exponents if multiplying. to write the value as a number between I and 10 multiplied by b) Subtract exponents if dividing. a power of 10. But there are times when you will want to 3. Convert the new number back to scientific notation. change that. For example, you may want to show the number Here's an example of multiplication. in thousands or as a fraction. Or you may want the exponent to be a specific value. The resulting numbers will still be in (6.4 x 103)(3.1 x 102) scientific notation, but not in standard format. Here are 6.4 x 3.1 =19.84 several examples to show how it is done. 10'x102 =105 Assume you have the number The product is: 4.7 x 10; 19.84 x 105 You want the numerical value to be between IO and 100 Note that the numerical value is larger than ten so we convert by the appropriate power of 10. To do this, multi- multiplied it to scientific notation. ply 4.7 by 10 to get 47. Since you multiplied the number by 10, you have to divide the power of 10 part by 10 or 1.984 x 10' x 105 103/10=102 To get to a single power of 10 again, just add exponents since you are multiplying. The new expression is 1.984 x 106 47x1022 Here's how division works. Another way to look at that is that you moved the decimal point on the number one place to the right. As a result, you (3.2 x 106)1(8.0 x 102) have reduce the exponent by one. In either case, the value to First, divide the numerical values or didn't change, just its form. Here's another example. You have the number 3.2/8.0= .4

~~2.9 X 10 -4 Then subtract exponents.~~

~~You want the power of IO to be 10-6. That is equivalent to 106/102 = 106-2 =104~~

~~71 The new value is: Or,~~

.4 x 104 1/4 x 10-8= 2 x 10-4 To put it in correct scientific -notation form, move the If the exponent is not even, then simply move the decimal decimal point to create a number between I and 10: point one place to the right (or left) on the numerical value 4.0x10-'x104 and adjust the exponent accordingly. Now add exponents: V3.6 x 10-5 =V.36x 101x 10-5= V.36x 10-4 =.6x 10-2 =6.0x 10-3 4.0x104-1= 4.0x103 Or, you could have moved the decimal point the other way. Adding a positive and a negative number is the same as taking It doesn't matter as the result is the same: their difference and using the sign of the larger. x Here's a more complex problem with both multiplication V3.6 10-5= V36 x 10-1x 10-5 = and division as well as some negative exponents: V36 x 10-6=6.0 x 10-3

(4.5 x 10-3)(6.8 x 105)/(7.2 x 10-4) First, do the multiplication in the denomenator. Practice Problems 12 and 13 Try these yourself to ensure you understand the concept. 4.5x6.8 =30.6 U. (2.2 x 10-4)2 Add the exponents: 13. 1/5.8 x 107 10-3x105 = 105-3 =102 The product is: Addition and Subtraction It's not likely that you'll need to add or subtract numbers in 30.6x 102 =3.06x 10' x 102 =3.06x 103 scientific notation form. But here's how to do it. Now the problem is: Remember, when adding or subtracting decimal fractions you had to line up the decimal points first? To add 12.36 (3.06 x 103)47.2 x 10-4) and .0178 you did this: Dividing the numerical values first gives: 12.36 3.06/7.2 = .425 or 4.25 x 10-1 + .0178 Then subtract the exponents: 12.3778 103 X 10-4=103-4=103+4 =107 You did the same thing to subtract. For example, 105.9 less The new value is: 2.348 is: 4.25X10-1x107= 4.25x106 105.900 - 2.348

Practice Problems 10 and 11 103.552 The only way to master this is to get some hands -on To add experience. Try these problems: and subtract numbers in scientific notation, you have to do the same thing. You do that by adjusting the 10. (1.2 x -3)(4.5 x 10-6)/(7.8 x 10-9) numerical value of one number until the exponents on the 11. (3.5 x 107)49 x 10')(2.4 x 106) powers of 10 are equal. The problem below illustrates that: (4.9 x 103) + (7.5 x 104) Let's make both powers of 10 have exponents of 3. Squares and Square Roots (4.9 x 103) + (75. x l03) Squares and square roots are also common operations. Now, Squaring a number is just multiplying it by itself. Therefore, all you do is add the numerical values and attach the same power 10. you can use the multiplication procedure described above. A of short-cut is to just multiply the numerical value by itself, then 79.9 x 103 double the exponent value. For example: Readjust to scientific notation: (8.8 X 10-4)2= 8.8 X 8.8 x 10-8= x 77.44 x 10-8= 7.744x 101x 10-8 = 7.99 104 7.744 x 10-7 Here's a subtraction problem. (3.1 x 10-5)-(8.2 x 10-7) To take the square root of a number in scientific notation Let's use 10-7. form, the exponent has to be an even number. If it is, just take the square root of the numerical value, then halve the expo- 3.1 x 10-5= 310x 10-7 nent value. (310 x 10-7)-(8.2 x 10-7) = 1/9x106 =3X103 301.8 x 10-' 72 You can use the current value in that form, but normally if the value is less than one ampere. then we use milli or micro Practice Problems 14 and 15 amperes instead. Let's use milliamperes here. Since milli is Do these for some experience: one thousandth, then our power of 10 should be 10-3. As a 14. (2.7 x 105) +(5.6x 104) result, we have to readjust the decimal point on the numerical 15. (3.1 x 10-2)(8.7 x 10-3) value. 1.25x10 -2= 12.5x10-;

Now, we can drop the I0 -' and simply say that the current is Units and Powers 12.5 milliamperes or 12.5 mA. You get the idea? Each electrical characteristic is expressed or measured in What if you go the opposite way and want to calculate the special units. For example, current is measured in amperes. resistance given the values of voltage and current. Let's use You are probably familiar with most electrical units, but the the values above. V = 5 volts and I = 12.5 mA. What is the most common ones are summarized in Table 3. resistance? R= V/I= 5/12.5 =.4 ohms TABLE 3- COMMON ELECTRICAL UNITS Ooops! The value is supposed to be 400 ohms. What hap- Electrical Unit Abbreviation pened'? The answer is that all values used in electronic for- Characteristic mulas must be in basic units, not in sub- (smaller) units or Volts V Voltage super- (larger) units. We used 12.5 mA in the formula. That Current Amperes A value. To Resistance Ohms tt has to be expressed in amperes (A) to get the right Impedance Ohms It do this we use scientific (or engineering) notation: Power Watts W Capacitance Farads F 12.5 mA =12.5 x 10-3 A Inductance Henries H R= 5/(12.5 x 10-') =400 ohms Keep this important fact in mind: Use only bask electrical learned earlier, very large and very small values are As you units in formulas, not sub or super units! common. So, scientific notation is commonly used to express these values. However, it is common practice to use certain multiples or submultiples of those units. For example, the More Examples terms milli, micro, nano, and pico are used to represent very Now, let's take some more examples. You are given a value small values while kilo, mega, and giga are used to represent of 268 mV. To get scientific notation, all you do is replace the very large values. Here's what each of these terms mean: mV with 10-3.

milli =one thousandth =1/1000 = .001 =10-; 268 x 10 -3 micro = one millionth =1/1,000,000 = .000001 =10-6 nano = one billionth =1 /1,000,000,000 = .000000001 =10-9 Then convert to a number between I and 111. or pico = one trillionth =1/1,000,000,000,000= . 2.68 x 10-1 volt 000000000001=10-12 Let's take another example. The voltage (V) across a load than a unit. Those are called sub units since they are smaller is 12 volts. The load current (I) is 40 microamperes. What is kilo =one thousand = 1000 =103 the load power (P)? mega = one million = 1,000,000 =106 P =VxI giga =one billion =1,000,000,000=109 P =12 x (40 x 10-6) Those are called super units since they are larger than a basic Note what we did in writing out the current. We have to use unit. Numbers expressed using sub or super units are said to amperes in the formula. not microamperes. Since the subunit he in engineering notation. is microamperes, we multiplied the value by 10-6 since micro Here are some typical examples: means one millionth. That gives the units in amperes. The A millivolt is one thousandth of a volt (abbreviation mV). resulting power is: A microampere is one millionth of an ampere (abbreviation RA). 480 x 10 -6 watts A picofarad is one trillionth of a farad (abbreviation pF). We can drop the 10-6 and just say 480 microwatts (mW). A kilowatt is one thousand watts (abbreviation I KW). What about resistor values? Large values such as 47,000 A megohm is one million ohms (abbreviation I M). and 2,200,000 ohms are common. In that case, we can use A gigahertz is one billion hertz or cycles per second the kilo or mega prefixes. A kilo prefix means 103 so we (abbreviation GHz). divide the value by 1000 to get kilo units. The above prefixes can be attached to any unit to express a very large or very small value. 47,000/1,000 =47 kilohms or 47K ohms To express 2,200,000 in megohms, we divide by 106 or Unit Conversions 1,000,000. Let's look at some examples of how units are converted. megohm or 2.2 M If the voltage applied to a circuit is 5 volts and the resis- 2,200,000/1,000,000 =2.2 tance is 400 ohms, the current according to Ohm's law is: Or, you can go the opposite direction. A value of 3.6K I= V/R= 5/400 =.0125 A =1.25x 10-2 A (Continued on page 92) 73 By Marc Ellis

~~ON ANTIQUE RADIO~~

~~Firing up the,Crosley 50~~

THOSE OF YOU WHO READ LAST The tickler coil is the basis for the re- month's column will need no introduction generative circuit. When placed in close to the little one -tube set pictured on these proximity to the tuning coil, it feeds some pages. For those who haven't, it's a of the signal from the tube's plate circuit Crosley Model 50, a bottom -of-the -line back to the grid. The signal, now ampli- broadcast receiver of the mid 192O's. fied, reappears at the plate. Now some of "Low -end" set though it was, it still cost the reamplified signal is again fed back to fourteen and a half 1920's dollars (minus the grid, amplified further, and so on. tube, earphones and batteries). That was The continuous feedback and re- no mean sum. amplification process makes for a very Last month we explored the circuitry of sensitive receiver. But if the coils are the model 50 and took a close look at placed too close together, the set breaks some of its interesting components. This into oscillation. Maximum amplification month we're going to power up the set, is achieved with the coils just far enough connect it to a good antenna and ground, apart so that oscillation does not take and find out what we can hear. But before place. we do, you might want to look over the For a more- detailed discussion of the set's schematic diagram (shown in Fig. Crosley's circuitry, refer back to last I) -which supplements the pictorial di- month's column. Right now, what we Powering up the little set required only agram presented in last month's column. want to do is find out what happens when three 9 -volt transistor radio batteries wired the set is connected to a good antenna and in series and a D -size flashlight cell. Circuitry Review ground, headphones, and a source of Refer to Fig. I. The Model 50's single power. The headphones that I selected were a tube is connected in a simple regenerative pair of 2000 -ohm Trimms that are about circuit. Notice the two coils labeled Preparing for the Tryout the same vintage as the set. The antenna TUNING COIL and TICKLER COIL. The tun- Powering up the set means providing a and ground are the ones currently in use at ing coil forms part of the tuned circuit that I -1 -volt battery (the "A" battery) to light my ham station: an end -fed wire about selects the frequency of the station to be the filament of the WD -I2 tube, and a 22- 100 -feet long and a 10 -foot section of cop- received. It is tapped so that varying 1 -volt battery (the "B" battery) to supply per pipe driven into the Earth for most of amounts of inductance can be switched in plate voltage. When the set was new, the its length. series with the tuning capacitor. The- "A" battery of choice would have been a oretically, each position of the tap switch large, "telephone style" dry cell. The Moment of Truth gives the variable capacitor a different Though still available today, those cells Connecting all of that to the little tuning range. are prohibitively expensive. So I chose Crosley, I put on the phones and slowly ANT instead an ordinary D -type flashlight advanced the filament rheostat. WD -12's cell -which wouldn't last nearly as long aren't exactly easy to come by, and I as the "telephone style" cell. But, for the didn't want to feed the tube any more relatively brief time period required for filament voltage than it needed to do its TUNING testing, it would work just as well. job. As the battery became more ex- CAPACITOR The "B" battery was a different type of hausted, the filament rheostat be wo i2 could problem. You can't drop down to the cor- advanced to a higher setting -which is ner radio store anymore and buy a 22 -V2- why the set manufacturer provided it. COIL WITH volt battery. Some specialty stores do car- Soon, the WD -12 began to TAPS FILAMENT filament RHEOSTAT ry such batteries for older, tube -type hear- glow and I began to hear stations in the TICKLER ing aids. But they are quite small in size, phones. But before operating the set for COIL have a short life span and GND -you guessed any length of time, I wanted to drop the it -are a little on the expensive side. "B" voltage to the correct value. No The solution was to wire three 9-volt sense making the tube draw too much transistor batteries in series. The resultant plate current, thereby shortening its life. 27 volts could be dropped down to the By trial and error, I found that a series o o correct 221 -volt value by means of a se- resistor of about 4700 ohms would drop PHONES PHONES A B ries resistor. Though the transistor bat- the 27 volts supplied by the battery to the teries would be short -lived in this 22 -1/2-volts required by the tube, Now I Fig. 1 -This schematic diagram of the application, they are inexpensive and was free to operate the set secure in the Crosley 50 shows the extreme readily available very simplicity of its design. -two strong decid- knowledge that the tube was being oper- ing factors. ated as conservatively as possible. Evaluating Performance

lire first set Ira Lure I explored was the operation oI' the regeneration control. This is a knob that varies the distance between the tuning and tickler coils. Pull- ing it out brings the coils closer together. increasing plate -to -grid feedback: push- ing it in does the opposite.

I expected to notice a pronounced increase in sensitivity with the coils adjusted so that the set was just on the point of oscillation. Stations came in readily. and signal strength remained constant. regardless of the position of the coils. Per- haps the stations that I was listening to Ready for the listening test: Batteries, headset, antenna and ground are were strong a scnsitivit\ effect to connected and a logbook is handy to note stations heard too for be apparent. With the coils almost touching, sound would become garbled and "watery" sounding. That. I assume. indicated the onset of oscillation. By the way, if you should be experimenting with a regenerative receiver hooked up to an outside antenna. don't leave the set in an oscillating mode lòr more than a few seconds. When it oscil- lates. your receiver becomes a miniature transmitter that can radiate a signal for miles -possibly interfering with \arious radio services. My next project was to run some frequency- calibration curves on the set. wanted to determine what frequencies the numbers on the tuning dial corresponded to for each of the five tap positions. To do

that. I tuned in as many stations as I could in each tap position -verifying the fre- The Crosley 50's tuning dial is at left, and the filament rheostat at the right. quency of each station by tuning it in on a The regeneration -control knob is located directly above the tap switch. The plate - voltage dropping resistor can be seen in the upper right land comer. modern receiver with a good dial scale. The graph shown in Fig. 2 summarizes 11n my results. Tap I Ion which I was only able to pick up one station). Tap 4. and

100 Tap 3 might just as %1 ell have been left off the set. Taps 2 and 5 do an excel lent job of covering the entire broadcast band. I've 90 listened to many vintage radios through vintage earphones -hut most of the sets 80 were multiple -tube setups with a reason- able amount of output power. At the normal volume levels used when there's 70 power to spare. the earphone sound tends to be harsh and tinny. 60 But when there's just a couple of milli - watts of power going to the phones. things 50 sound quite different. The little metal di- aphragms are barely vibrating and your ears are alert to catch every sound. Under 40 those conditions, the reproduction has no trace of tininess and sounds are pure and 30 clear. In fact. you'd be amazed at how well you can hear at that minimal- volume 20 level. Try it some time and let me hear about your experiences! Well once again we've run out of space 10 for the month. But betbre signing off. a little reminder: We welcome tips. ques- o tions. and comments related to the an- 500 60U 700 800 900 1000 1200 1300 1400 1500 1600 1700 1160 tique -radio hobby. Write to Marc Ellis. RECEIVED FREQUENCY (kHz) -B Bi- Fig. 2 -This graph shows relationship between dia" readings and received C/o Hands-on Electronics. 5(X) frequencies for various tap switch positions. Counts Blvd.. Farmingdale. NY 11735. By Charles D. Rakes

~~L J D 1g0~~

~~Produce the most basic building -block circuits from inexpensive op -amps~~

THIS MON rH'S CIRCUS STARTS OUT BY decrease rapidly as the frequency in- C3 showing how easy it is to turn a low-cost creases. Resistors, RI and R2 cut the sup- 47 +V IC into a number of basic building -block ply voltage in half to provide a bias circuits. that can stand alone, or be used voltage to the positive input of the op -amp as an important functioning block in a (U1) through R3. That automatically sets R3 TEXT) future project. In fact I find it worth while the output voltage to one -half that of the 10K to keep a similar set of building blocks on power source, to allow an even up -and- Rl C2 the bench ready to use in testing a new (SEE TEXT) down output swing. zz project idea. Such an approach won't By removing the R and C components solve all of your project needs (to think so from the circuit, a DC Voltage Follower is 1 OUTPUT would be absurd), but when any of the produced (as shown in Fig. 2) that makes 11 LM324 blocks can be used, it can certainly speed an excellent buffer stage to operate be- up the process of designing, building, and tween a high- output impedance DC cir- checking new circuits. cuit, and a driver or output stage. The recipe: Take a popular, low -cost IC One of the most useful building -block Fig. 3-The gain of the Inverting Amplifier its input (in this his case the LM324 quad op -amp), circuits that an op -amp can provide is the -with impedance set by the value of R1 and gain set add a few support components, shake gin- fixed gain AC amplifier. By selecting the by the combination of R1 and R2- gerly, and presto!- you've got four basic value of two resistors its gain and input can be preset to almost any value building -block circuits to play with. Ac- impedance set can be to any value. from 1 to over 100. tually, unless you live on the yellow brick road, the more predictable route to take is and the circuit's voltage gain is set by the to duplicate the following circuits. combination of RI and R2 by using the following simple formula: Voltage Follower R2 /RI = gain. Figure I shows an AC Voltage -Follower Oc built around just one of the op-amps con- OUTPUT For example; If the input impedance tained in a single LM324. The high input needs to match the ouput of a 1000 -ohm impedance of the Voltage -Follower circuit dynamic microphone and a voltage gain makes it an ideal electronic matching de- Fig. 2 -By removing the R and C of 100 is required, then RI would be 1000 - vice to connect between high and low components from the Fig. 1 circuit, ohms and R2 would be 100,000 ohms. impedance circuits. you are left with a DC Voltage With a fixed input impedance of 1000 - The circuit's voltage gain is one, and Follower, which makes an excellent ohms, the gain can be set to 10 by simply the frequency response is nearly flat from buffer stage to operated between a changing R2 to 10,000 ohms; to 50,000 high output impedance DC 10 Hz to 40 kHz. Above 40 kHz, the gains circuit, ohms for a gain of 50; and to 200,000 and a driver or output stage. ohms for a +5 -16V circuit gain of 200. PARTS LIST FOR R1 R2 PARTS LIST FOR THE 10K 10K THE VOLTAGE FOLLOWER INVERTING AMPLIFIER

100 -WVDC mylar C1- .1 -µF, 100 -WVDC mylar capacitor capacitor C2- .22 -µF, 100 -WVDC mylar C2- .22 -11F, 100 -WVDC mylar capacitor capacitor R1, R2- 10,000 -ohm, '/4 -watt C3-47 µF, 25 -WVDC electrolytic resistor capacitor 111111111 R3- 1- Megohm, 1/4 -watt resistor R1, R2 -See text 11 LM324 OUTPUT U1 -LM324 op -amp integrated R3, R4- 10,000 -ohm, 1/4-watt circuit resistor IC socket, perfboard, etc. U1 -LM324 op -amp integrated circuit Fig. 1 -The Voltage Follower, cir- Inverting Amplifier cuit built around an LM324 quad op- IC socket, perfboard, etc. "Ille block circuit (of Fig. 1) can be built amp integrated circuit, has a high as an inverting or input impedance, a voltage gain of noninverting amplifier The maximum obtainable gain that a one, and a frequency response that stage with the gain preset to almost any single op -amp stage can offer is deter- is nearly flat from 10 Hz to 40 value from I to over 100. The Inverting mined and limited by several internal de- kHz -above which gains decreases Amplifier circuit is shown in Fig. 3. The sign factors -including the amp's open - rapidly as the frequency increases. input impedance is set by the value of RI, loop gain figure and the amplifier's inter- 76 LIST FOR nal frequency- compensation network. inverting configuration. So if the circuit is PARTS Just remember, that as the gain goes up general -purpose in nature, you can use the THE SOUAREWAVE the frequency response goes down. And simpler inverting formula for both. GENERATOR when used in a general- purpose audio am- 100 -WVDC mylar plifier, a maximum gain -per -stage of 100 Squarewave Generator capacitor would be a good value to shoot for with [he Squarewave Generator, shown in C2- .1 -p.F, 100 -WVDC mylar the LM324. Fig. 5, is another handy-dandy building capacitor block that can be a real helpmate in the R1, R2- 10,000- ohm, 1/4-watt Buffer Amplifier design and evaluation of new circuits. The resistor A noninverting Buffer-Amplifier cir- oscillator can be tuned, with the compo- R3, R4-1000 -ohm, 1/4-watt resistor cuit is shown in Fig. 4. The main nent values given from about 1.5 kHz to R5 -2200 -ohm, 1/4-watt resistor difference between the previous circuit over 4 kHz. And with new values for CI R6- 25,000 -ohm potentiometer and this one is that the output remains in and R6, it can cover the frequency range U1 -LM324 op -amp integrated phase with the input signal. A number of of 1 Hz to over IO kHz. circuit active filters (such as the XMl Electronic R4 +6- 6V IC socket, perfboard knob, etc. Crossover featured in the November 1987 1K issue of HOE), oscillators, and other spe- PARTS LIST FOR THE in R2 cial function circuits require that -phase 10K INSTRUMENTATION AMPLIFIER signal relationship. C1- .1 -µF, 100 -WVDC mylar The method used in selecting the gain R3 1K C2 capacitor C4 1 47 R1- 1000-ohm, 1/4-watt resistor Cl + +v (-° OUTPUT R2- 10,00012, 1/4-watt resistor 01 S1- Single -pole 4- position switch R3 R4 FLI1 U1 -LM324 op -amp integrated 10K 10K R6 25K circuit IC socket, perfboard, wire, terminals, etc. Fig. 5 -The Squarewave Generator's C3 in this case is to a I -volt level. can be varied from .22 output frequency With SI in position I, the circuit gain is . about 1.5 kHz to over 4 kHz (with only I, but with the voltage follower cir- the component values given).

~~AC IN~~

~~AC sr 4 Fig. -The Buffer Amplifier differs INPUT from the Inverting Amplifier in that the ) Buffers output waveform is a carbon - copy of the input signal.~~

~~PARTS LIST FOR THE BUFFER AMPLIFIER~~

C1- .1 -µF, 100 -WVDC mylar capacitor Fig. 6-The Instrumentation Amplifier -built from the previous building C2,C3- .22 -µF, 100 -WVDC mylar blocks -is ideally suited for mating with an oscilloscope or an capacitor AC voltmeter for checking low -level audio signals. C4- 47 -µF, 25 -WVDC electrolytic capacitor The simplest way to vary the frequency cuit the loading effect on the monitored R1, R2-See text range of the Squarewave Generator, is to circuit is at a minimum. In position 2 the R3, R4- 10,000 -ohm, 1/4-watt change the value of Cl. gain is times 10. resistor Start with block amp #1 and build it to U1 -LM324 op -amp integrated Instrumentation Amplifier match the circuit shown in Fig. I, using circuit What would this little gathering of the component values given. The remain- IC socket perfboard, etc. useful circuits be if we left out the Instru- ing three block amplifiers are identical resistor values for the noninverting con- mentation Amplifier -which, coinciden- and are constructed to match the circuit in figuration is different than the one used for tally, can be made by stringing four of the Fig. 3, using the component values given the inverting type, and it goes like this: above building blocks together (Fig. 6). for Fig. 3, with the exception of the values The Instrumentation Amplifier is ideal- of RI and R2 which are taken from the RI + R2 /RI = gain. ly suited for mating with an oscilloscope parts list for Fig. 6. Connect the four amps With the same resistor values, as used in or an AC voltmeter for checking low -level together. the Inverting Amplifier, the gain is: audio signals. If a I- millivolt wiggle on Remember that the largest building your scope looks like a mini snake, then started out one block at a time, so give the 1000 + 100,000 /1000 = 101, build this amplifier and boost the snake's building block design approach a go and which is very close to the gain of the size to that of a Loch Ness monster, which see what you come up with.

~~77 By Joseph J. Carr, K4IPV~~

~~RA\ D] AIN HA M RADIO~~

~~Why is my receiver dial all scrunched up....while yours is not?~~

HAVE YOU EVER NOTICED THAT SOME note that 1610 /550 and 2065/1005 not /FminF are radio- receiver dials are linear, while Lmax/Cmin - Finax the same number! That is, 2.93 does not others are not? Some receiver dials are For example, the AM broadcast band on equal 2.06, which means that a radio with equally spaced for equal frequency dif- most radios runs from 550 to 1610 kHz. a single -knob tuner will not track between ferences, while others have the calibration The frequency ratio for AM is therefore the RF-tuned circuit and the LO -tuned points spread out at one end and all 1610/550, or 2.93:1. The standard capaci- circuit. scrunched up at the other. Let's find out tor used in those AM sets (and most gen- why that happens. eral-coverage SW sets, as well) has a Coming Together Most radio receivers are tuned by an maximum capacitance of 365 -pF, so the Fortunately, there is an answer to the inductor -capacitor (LC) tank circuit minimum value is found (as shown in problem. Figure 3 shows three variations such as Fig. 1. The resonant frequency is equation III in Fig 1) by re- arranging the of the LO -tuned circuit designed to im- determined by the values of inductance equation. Working the arithmetic would prove tracking with the RF circuit. In Fig. and capacitance in the circuit, according show a required minimum capacitance of 3A, we see the use of a small variable to the formula in the figure. We can tune 42.5 -pF capacitor (Ce) in series with the main tun- the radio by varying either L or C. Most In addition to the inherent non -linearity ing capacitor (C2). That small capacitor is table -model radios (including most shor- of the tuning process, we also have to deal called a padder. We can also connect a wave receivers) use a variable capacitor as with tracking error. Modem radios are small capacitance in parallel with C2, in the main tuning control, while both AM built on the superheterodyne principle which case the small cap is called a trim- and FM auto radios usually use a variable (see Fig. 2) in which the desired signal mer (C, in Fig. 3B). In either case, the inductor. (RF) is mixed ( "heterodyned ") with a tracking-error profiles are about the same, The main problem causing the local oscillator, LO, signal. The output of but of opposite sense. The best kind of "scrunching effect" is seen by evaluating the mixer contains the following frequen- tracking (Fig. 3C) combines CI, and C, in the equation for resonance (see Fig. 1) to cies: RF; LO; LO + RF; and LO-RE the same circuit. see what happens when either inductance Some modern sets have a slightly dif- (L) or capacitance (C) are varied. Note RF ferent dial -linearity problem if they use that a squareroot symbol appears in the variable- capacitance diodes (varactors) equation. That fact alone tells us that the Cl instead of mechanical IF capacitors. Figure frequency change is not linear with re- 4A shows the simplist varactor-tuned LC spect to L or C change. circuit. The capacitance that is needed to In fact, if you are upon your math, you resonate the inductor is the junction ca- might recognize that the curve will be a pacitance of diode Dl (i.e., Ci). The junc- "parabola." The max/min frequency ratio tion capacitor is varied by a DC tuning - is the square of the mar /min capacitance voltage, Cv. Capacitor Cl is used to block ratio: the DC tuning -voltage in order to keep it from being shorted to ground through the Fig. 2 -In addition to the inherent non - inductor. If Cl is very much larger than Cí linearity of the tuning process, there is also tracking error to deal with. Modern the diode capacitance, then Cl does not radios are built on the superheterodyne affect the resonant frequency very much. principle in which the desired signal In varactor -tuned receivers, the main I. RESONANCE: F = t (RF) is mixed ( "heterodyned ") with dial is hooked to a potentiometer that (in 2/N/LC a local oscillator (LO) signal. turn) is connected to a regulated DC voltage. Unfortunately, the C vs. V curve is II. RATIO: CMAX ( FMAX 2 A tuned circuit picks off either the sum very non -linear. That problem is partially CMIN MIN or difference of RF and W, and calls it the overcome by connecting two varactor di- intermediate frequency (IF). It is the IF odes back -to in III CMAX -back as shown Fig. 4B. CMIN that receives most of the radio's amplifica- FMAX 2 tion and bandpass filtering. Straightening the Dial FMIN The superhet (as it is called) is spec- If you look at your AM car radio, you Fig. 1 -Most radio receivers are tuned tacularly successful, but there is a prob- might notice that the dial tuning is nearly by an LC tank circuit, with the resonant lem or two. Let's consider a frequency determined by the values of standard AM linear. In other words, the distance on the band receiver with inductance and capacitance. Most table - the usual 455 -kHz IF dial for equal frequency differences are model radios (including most shorwave section. The RF section tunes from 550 to the same across the dial. How do they do receivers) use variable capacitors as 1610 -kHz, so the LO must tune (RF + IF) it? Other radio receivers also have linear the main tuning control, while AM and frequencies from 1005 kHz to 2065 kHz. tuning. Let's see what tricks are used in FM auto radios use a variable inductor. Remember our earlier discussion? Then those sets.

~~78 FREQUENCY PLATE TRACKING ERROR PROFILE MIN. MID MAX~~

SHAFT C2 STRAIGHT -LINE STRAIGHT -LINE CAPACITANCE FREQUENCY A A B Fig. 6 -The shape of the rotor plates of the tuning capacitor determines the linearity. By far the most common form is the straight -line capacitance type shown in "A;" with a more expensive, and less common, form of variable capacitor -the B straight -line frequency type-see "B."

rite core of the inductor (Fig. 7) is moved in and out of the coil form to change the inductance. If the coil windings are even- 1® ly spaced (as in Fig. 7A), then we have the C2 same problem as before- except that it is

C T T straight -line inductance. But if the coil is pitch wound (see Fig. 7B), on the other Fig. 3 -Here are three variations of the LO -tuned circuit designed to improve hand, we can linearize the dial scale rela- tracking with the RF circuit: "A" uses a small variable capacitor (Cp) in tively easily. series with the main tuning capacitor (C2); in "B," a small trimmer capacitance In the pitch -wound coil equal changes in parallel with C2. The LO -tuned circuit in "C" offers (Ce) is connected of core position cause different changes of the tracking -error profile by combining Cp and Ce in the same circuit. inductance. In a resonant circuit, Most radios use a one -to -three section Figure 6 shows the end view of two however, that inductance non- linearity variable capacitor (Fig. 5) to tune the res- forms of rotor plates. By far the most turns into straight -line frequehcy. onant circuits. Each variable capacitor common form is the straight -line capaci- consists of a set of fixed stator plates insu- tance type shown in Fig. 6A. When we COIL WINDINGS EVENLY SPACED lated from-but parallel and meshed to- graph capacitance vs. shaft rotation, we gether with -the movable rotor plates. get a straight line. But that also results in COIL FORM /CORE The total capacitance is determined by the dial scrunching because of the squareroot mentioned earlier. area of the plates facing each other. As the problem TUNING shaft rotates, the rotor plates become A more expensive, and less common, STUB more or less meshed with the stator form of variable capacitor is the straight - EVENLY WOUND plates, and capacitance changes. The line frequency type shown if Fig. 6B. By shape of the rotor plates sets the linearity. making the shape of the rotor plate as COIL WINDINGS UNEVENLY SPACED shown, the change in capacitance with shaft rotation becomes non- linear. but the frequency of the resonant circuit is then linearized. TUNING L1 AV Car radios use a different method. In STUB order to make manual. mechanical push- PITCH WOUND buttons easier to design, car-radio tuning vary circuits vary the inductance rather than Fig. 7- Car -radio tuning circuits the inductance rather than the capaci- the capacitance. In those radios, the fer- tance. If the coil windings are evenly spaced (as in "A "), we have the same A REAR CONTACT SPRING problem as before-except that it is BEARING straight -line inductance. But if the ROTOR PLATES coil is pitch wound ( "B "), we can linearize the dial scale. I` A L1 AV Bandspreading Once upon a time. all general -coverage shortwave receivers of any quality (and STATOR most Of low quality I had two tuning dials: PLATES main tuning and hundspreud. The main B tuning dial was scrunched up on one end INSULATORS Fig. 4 -Some modern sets use variable - and spread out on the other. The hand - three - capacitance diodes (varactors) instead Fig. 5 -Most radios use a one- to spread dial. on the other hand. was rela- capacitor to tune the of mechanical capacitors. A simple section variable tively linear. Actually. if you measured varactor -tuned LC circuit is shown in resonant circuits. Each variable with a fine rule or micrometer. you would "A." The non -linearity of varacitor- capacitor consists of a set of fixed both dials were non -linear, but tuned circuits is partially overcome stator plates insulated from -but find that by connecting two varactor diodes parallel and meshed together with - the bandspread dial was much better than back -to -back as shown in "B." the movable rotor plates. (Continued on purge 98)

~~79 By Herb Friedman D J i 1_ ON COMPUTERS It takes no space to tick away the time~~

DONE DAY I REALIZED THAT MY IBM /PC than three extra: slots; and because the XT had had it. Its five slots could no longer had 640K of RAM on the motherboard, I accommodate my assortment of "must wouldn't have to use up a slot for memory have" adapters. Since one slot was expansion. needed for the disk controller, another for My rapture with the XT-clone lasted a Paradise monitor adapter that provided exactly one day. The dual Paradise compatible IBM -type monochrome and monitor, the floppy and hard disk control- graphics monitor adapters in a single slot, lers, the parallel and serial adapters left and a third slot was used for the hard -disk over from my first PC, an internal controller, under the best of circum- modem, and my mouse adapter used up stances. I would be juggling cards to ac- seven of the eight slots. A clock/calendar commodate 5I2K of memory, two serial adapter used up the final slot, leaving no ports, a parallel printer port, a joystick room for anything else. port, an Apple /IBM converter, and any- Something had to go because I needed The SMT clock calendar is actually assem- thing else that came down the pike. at least one slot for an IBM /Apple -Macin- bled inside a 28 -pin ROM socket that It seemed I was always playing musical tosh converter, and it looked like the clock plugs directly into an empty ROM socket slots with PC, but I my knew the game was the most likely candidate for banish- on an XT-clone motherboard. If necessary, was up when I actually wore out a slot. ment. But I like a full -time clock/calendar another ROM can be mounted piggyback Adding an expansion unit was out of the that keeps track of the time and date: I on the clock module. question because it costs almost as much truly detest entering the time and date as an XT-clone computer, and several when booting up, particularly because my AUTOEXEC to enter the time and date. adapters that I use won't work in an ex- AUTOEXEC.BAT file does so much I can pansion box. walk away and prepare a sandwich before The Zero -Slot Option So it was time to move up to an 8 -slot the computer is ready for use. The last Fortunately, I discovered the No-Slot XT- clone, which actually gave me more thing I wanted to do was interrupt the Clock from SMT (Systems Manufacturing Technology); one of those cute, worth- while ideas that never seems to get the attention it truly deserves. Basically, instead of using a slot- mounted card to provide the clock /calendar hardware, SMT (as shown in Fig. 1) built a real -time clock/calendar into a CMOS IC, then installed the IC along with two miniature lithium power-backup batteries in a 28- pin ROM socket that fits both IBM /XT/ AT and Apple compatibles. I simply don't have time nor the space to discuss all the computer models, so we'll simply cover the XT-the most popular computer of all, and the one that I use. (Keep in mind that the SMT clock works with the 8088, V20, 8086, 80186, and V30 microprocessors.) If you look at an XT's motherboard, you'll find several empty 28 -pin ROM sockets. You can plug the SMT No -Slot Clock into any empty socket. And if for some reason you don't have an empty socket, simply remove one ROM, install the SMT clock, and then re- install the ROM piggy -back on the SMT clock. If there is some reason why you can't piggyback a ROM, you can install the clock/ Here's how the clock module looks when installed in the last empty ROM socket calendar module on certain daughter - on an XT motherboard. Note the empty ROM socket just right of the module. (Continued on page 95) CoMASTER THE NEW ELECTRONICS WITH McGRAW- HILL'S

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THINK TANK ll What to do with number two? +9V DOKAY. SO \Y1l 'I.NI IN AN IDEA ¡OH I III length of insulated wire and an alligator Think Tank, and in the due course of time, clip to the outer connector, a small nail or you got your copy of the Fips Book. Now solid wire lead as the inner, or probe lead you've got another idea, and you'd like to connector. To change functions, simply send it in, but you don't want another unplug the one and plug in the other. copy of the Fips book. What do you do? Well, you could simply forget about it, R5 3.3MEG depriving your fellow readers of the benefit of your thinking. But we've been doing a little thinking about it. (we do think once in awhile -it's good exercise for the brain as long as you don't overdo it). If you'd like to submit another idea, by all means do so, but make sure that you mention in your cover letter that you already have the Fips book. We'll send you a different book (of our choice. of course) that, as an electronics hobbyist. you're sure to value. So sharpen up that pencil, put on the thinking cap. put your shoulder to the D2 HEP wheel, your ear to the ground, your eye on R0052 the ball, and your nose to the grindstone. And then let's see if you can work in that Fig. 2 -This simple light- triggered position! B circuit can be configured to be used by the visually impaired as a light- sensor Here are this month's winners. Thanks Fig. 1 -SCR1 is latched into conduction or, for technical- minded individuals, it a bunch fellows: the Fips books are all on when the output of the 555 oscillator can be used as a simple continuity tester. the way! timer goes high. Once energized, SCR1 continues to conduct until the current through it (principle current) is brought If you want to change the sensitivity. Latched Touch Switch below the holding- current level (IH) simply reverse the collector and emitter Ibis conlcnicnt Latched Touch Switch by pressing the reset switch (S1). leads of the phototransistor. Nothing here should find a lot of application for any is "cast in concrete" and you should feel electronics hobbyist. As it's configured reset switch can be replaced by a couple of free to experiment with values and parts (See Fig. IA.). touching the touch -pad pennies, as well. That would, of course, designations. -Frank Pascoe, Saskatoon, causes the output of the 555 (U I) at pin 3 increase the price, but only by two cents! Saskatchewan, Canada. to be high. That high. fed though DI, Pete, because you really sent in TWO di- Good going Frank. This is just the sort triggers SCR! into conduction, energiz- agrams, I'm sending you two books. And of project we're looking for, but short of ing the load. The load circuit can be a low - if you're inclined to do so, by all means, simply sounding to advise the presence of current buzzer, a Piezo buzzer, an LED or please do it again. light, I wonder if using a powerful flash- whatever. light might not cause the alarm to go off Once energized. SCRI continues to Hear The Light? when an object reflects light to this unit? conduct until the current through it (prin- This simple light- triggered circuit can That way, it could advise the visually im- ciple current) is brought below the hold- be configured to perform two functions: It paired of the presence of objects in their ing- current level (IH) pressing the reset can be used by the visually impaired as a path. switch (SI). light -sensor or, for technical-minded indi- Now if you want to control a I I7V AC viduals, it can be used as a simple con- Signal Injector device, such as a TV set, you can add the tinuity tester. Jim Thompson, of Greenville, NC. sub -assembly shown in Fig. IA. Just As can be seen by Fig. 2, the circuit is writes to say that Every technician needs a make sure the relay contacts are properly small enough to be built on perfboard small, portable signal source in the audio - rated for the anticipated load current. And using point -to -point wiring, and housed RF range. The circuit shown in Fig. 3 can one other thing of interest-for the touch in a dime coin tube. The sensor, Q3, (a put out signals from about 2 kHz to RF in pad. I use an ordinary, copper, US pen- FPT-I00 phototransistor) should be the broadcast band, with output levels ny! -Peter E. Hughes. Eden Prairie. mounted in a plastic mini -plug shell, running from a few millivolts to about MN. using the open end for light access. eight volts peak -to -peak. Actually, you Okay Pete. The only additional sugges- To change to unit to a continuity tester, can use the circuit to check out AM- tion I might make is that probably the simply prepare a second mini -plug with a broadcast receivers by signal injection 84 TO TO TOUCH STATIC PLATE LASH

~~R1 ¡ L. 220121 kH7 U1 R2 555 ", RED1RED 4.71(1 TIMER (FAIL) o O PROBE 8V PP R3 C2 33012 .1 8 -0 r COMMON~~

Ula B1 Fig. 3 -The Signal Injector can put out signals from about 2 kHz up to the R2 1 -21458 9V RF range, with levels running from a few millivolts to about eight volts. 100K U1b from the antenna right to the speaker terminals. The Injector consists of a single 555 oscillator /timer (U I ) connected as an astable multivibrator. It puts out a squarewave with a fundamental frequency of about 2 R1 1K kHz with harmonics that are modulated at LED2`;f 2 kHz, and the harmonics go well into the GREEN broadcast band. Power is provided by a 9- (PASS) volt transistor -radio battery. Nothing special is required in the de- I sign or assembly; use wiring just good Fig. 5 -In the Leash Tester circuit, Q1 and soldering practices. A length of wire and Q2 form a Darlington amplifier. The (about I0- inches long) with an alligator high current gain of the Darlington clip on one end is used for the common Fig. 4 -This simple amplifier circuit causes an increased voltage across R1. lead. A modified VOM test probe cut to a can be used with small radios, tape recorders. length of two inches including the probe is record players, or Jell wired his tester in a small experi- as a PA amplifier. For long- lasting used as the signal- carrying lead, which menter's box using a metal plate (made power. use a six -volt lantern battery; was from a peanut can) to close a (normally - cemented to the plastic box. or if lightweight portability is desired. open, It was shortly after Jim built the unit use a nine -volt transistor -radio battery. momentary- contact) pushbutton that he had the opportunity to put it to an switch, SI. When SI is depressed, firing unusual application. In a new house under up the circuit. while simultaneously construction, the sheetrock crew inadver- small a speaker. youll blow the cone checking the static leash. Since the circuit tently covered an outlet box. He then con- across the room! Anyway. thanks Myron. is on only momentarily. the battery will nected the injector at the circuit breaker and give yourself a pat on the back. Your last a good, long time. and with a small, portable AM broadcast copy of the Fips book is on the way! To calibrate the circuit, power it up with receiver, was able to get his first cut in the no contact to QI's base. Rotate R2 until sheetrock within four inches of the hidden Leash Tester the green light comes on, then turn R2 outlet box! Jeffrey Muslin, of Cudahy. WI came up back a hair past the point where the red Super, Jim. And guess what YOU have with this one, and we think it's as neces- LED comes on. That's all there is to it. coming in the mail! sary as a static leash! But let's begin at the While none of the components are crit- beginning. What's a static leash? Why it's ical, be sure to use 1/2-watt or higher rated Cheapie Amp one of those conductive wrist straps that resistors for R3 and R4. Myron Hilton of Union. ME came connects the human body to ground. so Thanks to you too, Jeff. A tip of the hat across with a quick -and -dirty amplifier static charges in and around the shop and a Fips book. with more applications than you could won't blow all your CMOS devices. The shake a stick at just in case you're into tester gives you an at- a- glance indication Time-Delay Touch Switch stick- shaking. Among other things. My- of how good (or bad) your wrist strap is. I'd like to thank W. Knight, of Renton, ron recommends it for small radios, tape Turn your attention to Fig. 5. As you WA for his submission on the Time -Delay recorders, record players, or its use as a can see, QI and Q2 form a Darlington Touch Switch, and at the same time ask PA amplifier. (See Fig. 4.) amplifier. whose bias current comes from that on future submissions, he also Another interesting aspect of the circuit V + , passing through the (good) static provide us with his first name! We're not is that nothing seems critical in building leash, your hand. the touch plate, and into all that formal around here. Matter-of- the circuit; almost any components that QI's base. The high current gain of the fact. when people call me "Mr. Wels," I you may have lying around the shop Darlington causes an increase in the volt- always tell 'em that "Mr. Wels is my fa- should do the trick. And if you want long - age across RI . U I is a dual op -amp config- ther-I'm "Byron." lasting power, use a six -volt lantern bat- ured as a comparator whose threshold is What we actually have here, is a very- tery; or if lightweight portability is desir- set by R2. When the voltage at Q2's emit- clever idea for a burglar alarm system. ed, use a nine -volt transistor-radio battery. ter is below the threshold voltage (open And it appears that the circuit will work According to Myron, the only really crit- circuit). the op -amp's outputs go low - with almost any system. Take a look at the ical point is the loudspeaker, which ought causing the red (FAIL) LEDI to light. circuit in Fig. 6. Built around a 555 os- to have at least a five -watt capacity. When Q2's emitter is above the threshold cillator/timer (which provides a 10 -sec- Myron, that little wing -ding must (closed circuit), the op -amp's outputs go ond delay) and a handful of support really kick out. Betcha that if you use too high; the green (PASS) LED2 comes on. components. the Time -Delay Touch 85 TO +12V ALARM NC O O R1 ;R3 51051 '2.7MEG O ONC Oc LEO1 O

LOOP U 1 a D2 D1 1/4 MC14584 1N4004 1N4004 +1 SCR1 12V 2N5060 G R4 R6 K 24K 9052 R2 UI 114 MC14584 2 -7MEG D3 ARM 1N4004 S1 13 12 11 10 C2 102 Ul-c 1'4 MC14584 04 1N4004 ATTACH TRIGGER WIRE TO THE LATCH Fig. 7 -This Burglar Alarm, built around the MC14584 Hex Schmitt trigger, NUT & BOLT detects intrusions through a series loop of normally -closed switches.

ISOLATE LATCH make up the entry -delay circuit, and relay with a 5 -volt coil. Radio Shack sells FROM METAL LEDI is used to monitor the status of the a similar relay a 12 STRUCTURE with -volt coil and with sense loop. Diode DI keeps LEDI from it, you could eliminate resistor R6. Fig. 6- The Time -Delay Touch Switch, charging CI when the loop is broken. Thanks Gordon, it's an extremely inter- built around a 555 oscillator timer Ulc, R2 and C2 form the exit delay cir- as (which provides a 10- second delay) and esting circuit well as being quite func- a handful of support components, cuit. SI is closed to disarm (silence) the tional. protects your valuables by stopping the alarm. The alarm is armed when SI is Well, that brings us to the end of an- would -be intruder before he can opened and C2 has charged. other column, and starts me to collecting actually enter a protected area. Normally, the circuit is disarmed by the schematics for the next one. Re- closing SI, which keeps C2 discharged. member, we don't just want clear, easy-to- Switch protects your valuables by stop- The output of Ulc will be high. keeping read schematics, we also want complete ping the would -be intruder before he can SCRI in the triggered state. The output of descriptions-that means, all compo- actually enter a protected area. The circuit Uld is low, sinking base- current away nents clearly labeled (parts numbers, and is connected to a door with a large latch - from QI, and keeping the relay in the values), the circuit's theory of operation the latch serving as the touch- switch con- deenergized state. The entrance delay cir- (I'm a stickler for knowing how things tact. If the latch itself is mounted to a cuit will have no effect in that mode. The work) and not just a here it is, put it metal structure. the latch must be iso- LED will still indicate the open or closed together and watch it work sort of expla- lated. status of the protective loop. nation-of the circuits as well. And He didn't want the system to be too To arm the circuit. check LEDI to please, make sure you have the right to obvious. so he uses a five- second delay on make certain that all the switches in the send in the schematics. Don't just copy the output of the 555 timer, which will sense loop are secured, then open SI. 'em out of some book, especially if that cause an intruder to assume that some- You'll have close to 20 seconds to leave book is copyrighted! If you have been thing (or somebody) else triggered the the premises. Following the time delay the procrastinating, get to work. Your copy of alarm. output of U lc goes low, removing the trig- the Fips book is here, waiting for you. While the circuit itself is straightfor- ger voltage from SCRI. The SCR con- Send your material to By Wels, Wels' ward and has no fancy curlicues, it is tinues conducting because of anode Think Tank, Hands -On Electronics standard: no claim is made for its novelty current from the LED. The output of Uld Magazine 500 -B BiCounty Blvd, Farm- other than the application, which we also goes high. removing the current sink ingdale, NY 11735. found to be exceedingly unique. Thanks from Ql. If you got out in time and the again Mr. Knight. and do hit us with an- loop is still keeping CI discharged. Ulb other' Your Fips hook is on the way. provides the current sink to QI, keeping the alarm silent. Another Burglar Alarm Should the protective loop be broken. Gordon Reeder. of Greensboro. NC, SCRI falls out of conduction and CI be- sent in an unusual burglar alarm sche- gins to charge. After a 20- second period, matic. which is shown in Fig. 7. The cir- the threshold of Ula will be reached. The cuit is built around a pair of delay timers output of Ulb goes high. removing cur- based on an MCI4584 Hex Schmitt trig- rent sink from the base of Ql. Base current ger. Among other things. it features 12- through R5 causes QI to conduct, activat- volt DC operation. low standby- current ing the relay and providing power to the draw, entrance and exit delays. and an SIREN terminals. At any time following or uncommitted pair of output contacts. during the entrance delay is triggered, SI Intrusion is detected by a series loop of can be closed to disarm or silence the normally- closed switches labelled Loop. alarm. A key switch. SI, is the only required No type number is given for Ql, which control. A bell or siren can be connected depends on the relay you elect to use. at the output terminals. UTA, R3. and CI Gordon used a 2N2222 and a small DIP "I only smoke when I'm angry:'"

~~86 By Marc Saxon~~

~~ON SCANNERS~~

~~A scanner with a flair for the weather~~

01 NEVER FORGOT IT: "WHETHER IT'S Inc., 7707 records St., Indianapolis, IN Ye Olde Mail Sack cold or whether it's hot, we must have 46226; or circle 88 on the Free Informa- to kick things off this month is a report weather, whether or not!" Miss Grundy, tion Card. that one of our readers-Charlie Cotter- my Third Grade teacher made our class man, KA8OQF, of Dayton, OH -re- repeat it in unison every time there was a Quick Fix ceived a nifty QSL card. Charlie's rainy or snowy day. Maybe that's why, to The idea of an "instant weather" chan- attractive card displays a vehicle (possibly this day, I'm always trying to find out the nel designed into a scanner may be new, his own) engaged in what appears to be a latest weather information. but sharp scanner owners have long road rally or similar activity. We're always Perhaps that's why I was so pleased to known how to jury-rig that feature into just happy to receive QSL's and shack photos see that someone finally got around to about any programmable scanner. I'll be from our readers. adding an instant -weather- information happy to share that how -to information Maybe you'll send us yours soon. capability to a full -featured scanner. And with you. Just be sure that you include a Manny Esposito of Tallahassee, FL that's just part of what the Regency self-addressed, stamped envelope. wrote to tell us about a local fellow who R-1080 scanner has to offer. Many scanners have their first channel was recently arrested in connection with The R -1080 features 30- channel recep- position set aside for use as the priority burglaries of almost a dozen area dry- tion covering the most popular scanner channel. When the unit's priority feature cleaning shops. The police said that when frequency ranges: 30 to 50 MHz; 144 to is activated, the scanner will sample the the burglars wanted time for their dirty 174 MHz, and 440 to 512 MHz. The man- frequency every few seconds when it is work, they monitored a police radio to ufacturer gets the scanning show on the either searching or scanning. If you pro- make certain that the neighborhood of- road by thoughtfully pre -programming gram your local NOAA weather station's ficers were occupied on assignments. into the memory all sorts of popular na- frequency into that channel slot, then The oddball twist to the whole thing tionwide public- safety frequencies. Of place that channel on LOCKOUT, whenever was that the man arrested worked for the course, you have the option of replacing you press the key that activates your scan- Florida Department of Law Enforcement! any or all of those frequencies with those ner's priority feature, your scanner drops The police never said why he always se- of your own selection. whatever it was doing, and instantly lected dry cleaning establishments. May- Reprogramming can quickly and easily brings you the weather station's transmis- be he found it pressing work. be accomplished by means of the front - sions. To resume the scanner's other ac- From California we hear from Bob H. panel keypad. It's as easy as using a push- tivities, simply deactivate the priority who says that many federal buildings and button telephone -and the data being en- feature. Until I learned that trick, I had installations have uniformed security po- tered reads out on a dual -level vacuum never used that feature at all! (Continued on page 95) fluorescent display. Still, the notion that its the unit can be removed from factory The R- 1080 -featuring sealed carton, plugged in, and it starts to 30- channel reception, receive, is tantalizing. front -panel By touching a single front -panel but- programming, a weather - ton, the R-1080 instantaneously goes into information search a WEATHER -INFORMATION SEARCH mode. mode, priority channel. The weather-information search mode lockouts, fast slow scan speeds. and memory rapidly locates an active NOAA VHF - backup (no battery channel in order to weather information needed) -comes bring you the current weather readings complete with power and forecasts. That's an interesting feature cord and telescoping that isn't usually included in scanners, antenna. at a suggested and we liked the concept. retail price of $199.95. Of course, the set also has the standard For more information on scanner features, too; priority channel, the R -1080. contact lockouts, fast/slow scan speeds, memory Regency Electronics. Inc., 7707 records St., backup (no battery needed), etc. The vol- Indianapolis, IN 46226: squelch controls aren't knobs, ume and or circle 88 on the Free they're the slide types. Information Card. The Regency R-1080 comes complete with a power cord and a telescoping antenna, and its suggested retail price is CARD $199.95. For more information on the CIRCLE 88 ON FREE INFORMATION R-1080, contact Regency Electronics, By Don Jensen

~~ON DX'ING~~

~~Isn't it about time that you discarded that 1987 calendar?~~

HEY, rr's F1i6K1'AKY. SUM:, I INU\\ grams. you've been busy tuning in all those SW One such ham bulletin is the IARN stations during the winter DX season. broadcast, heard twice daily, at 1530 and But, now it's time to take that old 1987 1930 UTC, Monday through Friday, on calendar off the wal I. And while you are at 14,275 kHz. Recently on the IARN bul- it. why not replace last year's model with letin, I listened to an interview with one of one of the really attractive 1988 calendars the network's controllers. There was also that a number of the world's major short- a newscast covering developments in the wave broadcasters send to their loyal lis- world of radio, including a Soviet plan to teners? put an amateur -radio operation in space- My favorite is the one offered each year perhaps even using slow -scan color TV to by Radio Beijing. It's always a beauty. communicate with hams around the Some years Beijing's calendar features globe. Not to mention a feature from the terrific photos of picturesque China. pages of QST, a ham magazine, about Other years. it has been lavishly decorated amateur radio activity during a 1949 natu- with full color illustrations of Chinese art- ral disaster in Ecuador. work. SWL's, as well as hams, are welcomed Radio Nederland, for another, sends into this voluntary- service organization. out an attractive calendar, as do the Voice You can get details by listening in the of Free China from Taiwan and Ger- IARN bulletin. There is no membership many's Deutsche Welle. The Voice of the fee to become a member of TARN. Just Andes, HCJB has handy desk calendars send 90 cents in stamps to the Interna- for members of its audience. There are tional Amateur Radio Network, Belgrade others too. (It can be a tough choice.) Lakes, ME 04918. If you haven't received your 1988 calendar, drop a note to your favorite SW In the Mailbox broadcaster and ask. But, remember This month we'll field a question from there's a little give coupled with the Ramon Fernandez (Puerto Rico) that I gimme -you should at least be a reason- could not fit in last month. But before ably regular listener to the station that getting to that, a reminder to the rest of gives out the "goodies." RADIO "SAN GABRIEL" you that your letters are always welcome. Calle So, why not share your recent loggings Emergency Net General Lanza No. 2001. Teléfono: 321 174 - 355371 with the rest of us. What are you hearing SWL'ing involves broadcasting sta- Casilla 4792 on SW? On what frequency? At what LA PAZ BOLIVIA tions and listeners. of course. It's one -way - time? Or perhaps you, like Ramon, have communication. from them to you; and This little guy with the microphone, in questions or comments about the DX'ing differs from two -way amateur -radio com- traditional Bolivian garb, is the symbol hobby? If so, write to me, Don Jensen, munication-in which licensed hams of Radio San Gabriel in LaPaz. Jensen On DX'ing, Hands -on Elec- communicate with each other, often with- tronics, 500 -B Bi- County Blvd, Farm- in the framework of regularly scheduled And there are some other frequencies and ingdale, NY 11735. Now to this month's networks. hours in the network system as well. query: The International Amateur Radio Net - Hams with important messages can "Is shortwave as common in other parts trork (IARN) is one of those ham nets simply break -in on the TARN frequency to of the world as AM radio (540 to 1600 with a special purpose; to provide world- pass along information. That makes it an kHz) or FM is here?" asks Ramon. wide communications in times of emer- interesting spot for shortwave listeners to The so- called AM band -hobby lis- gency. It has a membership of more than "watch" when an earthquake, flood or teners call it the medium wave (MW) 500 radio amateurs worldwide -and other natural or man -made disaster strikes band -is used for broadcasting around some SWL's. as well. anywhere in the world. the world. In most countries, it is the Several months ago. the network went In addition. some amateur stations also dominant band -though outside of this fulltime; meaning that its 20- meter fre- air regular transmissions of news and in- hemisphere, the "separation" between quency of 14.275 kHz is monitored by a formation that are decidedly one -way in stations is not the 10 -kHz standard com- net controller between 1400 and 2200 nature. Hams call them bulletins. And mon to this hemisphere. For instance, in UTC, weekdays. t r emergency traffic. A except for the fact that they are transmitted Europe, you wouldn't expect AM stations 10 -meter channel. 28.475 kHz. is used for in the single -sideband mode, they sound to fall on frequencies ending in 0, as they an hour or two beginning at 2300 UTC. very much like shortwave broadcast pro- do here.

88 Increasingly, however, FM (especially 1900 UTC with an English identification, BOOKSHELF FM stereo) can be found globally. Even in followed by a program of classical or pop- (Continued from page 24) the more remote parts of lesser -developed ular music. nations, stereo FM is available. And the Belgium -9,675 kHz, Belgian Radio termediate programmers. reason for its popularity abroad is the TV. Listen for "Brussels Calling," with The book is based on Borland's new same as it is here- superior musical re- news and music from 2100 UTC, follow- Turbo C compiler with its powerful inte- production. ing the station's interval signal and identi- grated environment that makes it easy to In those same Third World nations- fication. edit, compile, and run C programs. The South America, parts of Africa and south- East Germany -6,010 kHz, Radio author uses a proven hands -on intensive east Asia -domestic shortwave service is Berlin International can be heard here in approach and begins with the fundamen- very important because of distances be- its English- language transmission at 0200 tals of C programming followed by inter- tween stations and the national audience, UTC with news and commentary. mediate concepts of arrays and pointers, or because of the terrain that separates Greece -7,430 kHz, Voice of Greece. data structures, and the use of the C li- them. In the Andes Mountain valleys, for This station is not difficult to hear in North brary. Advanced topics, such as assembly instance, it is tough for local inhabitants America during the evening hours, until language interfacing using DOS -and to receive MW signals from beyond their about 0350 UTC. It is worth listening to ROM -based routines are addressed, all in immediate area. for its terrific music, even though the pro- And in places like Brazil and Indo- gramming is all Greek to you. nesia, people are accustomed to listening India -11,620 kHz, All India Radio. turbo ( Pn;ramminy to domestic shortwave stations. Those The General Overseas Service of the AIR tirtM IBM countries, for example, each have over has been heard with English news, begin- 150 SW outlets; not as many as medium - ning at 2045 UTC. wave AM stations (to be sure), but a sig- Mongolia -12,015, Ulan Bator's radio nificant number nonetheless. offers English -language programming Our SWL friend Ramon also passes here around 1200. You may well find inter- along the information that the Voice of ference, but it is an interesting catch. America is putting up a repeater station in Netherlands Antilles-21,685 kHz, Puerto Rico, which VOA plans to use to Radio Nederland also makes use of relay relay its broadcasts to the Caribbean, Cen- transmitters outside the home country. tral and South America. The station is You don't find too many SW stations on scheduled to begin transmitting by 1990, that high- frequency band these days. The CIRCLE 95 ON FREE INFORMATION CARD Ramon says. programs are relayed from the island of Bonaire, off the coast of South America. the context of the IBM programming en- Down the Dial You can't find RN's English programs at vironment. Here are some of the shortwave broad- 1830 UTC sign on. Topics covered include: C building cast stations of the world being logged by Peru -4,996 kHz, Radio Andina in blocks, loops, decisions, functions, ar- SWL's in North America recently. As al- Huancayo is offering one of the more con- rays and strings, pointers, keyboard and ways, all frequencies are given in kilo- sistent signals from that South American cursor, structures, unions, and ROM hertz (kHz) and times are referenced to country these days. In the evening hours BIOS, memory and the character display, Universal Time Code /Greenwich Mean (as well as early in the morning around CGA and EGA color graphics, files, Time (UTC /GMT) 0930 UTC), you can hear plenty of the larger programs, and advanced variables. Algeria -9,510 kHz, Radio Algeria typical and exotic melodies of the Peru- Turbo C Programming for the IBM, tends to pop up in unexpected spots in and vian high country. No. 22614, retails for $22.95 and is avail- out of the shortwave bands. This is a fre- South Africa -3,955 kHz, Radio Ori- able at bookstores, electronics dis- quency that has been reported heard at on is one of the home services of the South tributors or direct from the publisher African Broadcasting Corporation, the SAMS, A Division of MacMillan, Inc., ABBREVIATIONS same folks who bring us the Radio RSA 4300 West 62nd Street, Indianapolis, IN external service for listeners abroad. Look 46268; Tel. 800 /428 -SAMS. AIR All India Radio for this one in English around 2330 UTC. AM Amplitude modulation Another home service the is (modulated) of SABC OX'ing Listening to distant called Radio Five, which can be heard on shortwave broadcasts 4,880 kHz around 0330 UTC with music FM Frequency modulation and commercials. (modulated) Venezuela -4,980 kHz, Ecos del HCJB Voice of the Andes Torbes in the city of San Cristobal has IARN International Amateur Radio been logged, all in Spanish, of course, Network with a call -in game show and Latin kHz kiloHertz (1000 Hertz or rhythms around 0000 UTC-call it 2400 cycles) hours if you prefer, it's the same thing MW Medium wave - on RN Radio Nederland this frequency. SABC South African Broadcasting Credits: Norman Bobb, MN; Allan Corporation Courtney, KY; John Tuchscherer, WI; SW Shortwave Daniel Sampson, WI; David Morby, NY; SWL('s) Shortwave listener('s) TV Television Frank Orcutt, CA: Peter Dillon, MD; UTC /GMT Universal Time Code' Kenneht Cobb, ME; Steven Walley, CA; Greenwich Mean Time North American Shortwave Association, "The mouse you'll be working with VOA Voice of America 45 Wildflower Road, Levittown, PA in this class is neither a rodent VOG Voice of Greece 19057 nor an animated cartoon character."

~~89 GET YOUR FCC LICENSE (Continued from page 68)~~

Not for Beginners I've had a lot of electronics courses and I used a Q &A manual as a guide to review all my old notes and books from college. However, if you're a beginner, you'll find Kaufman's Q &A manual tough to follow. To be sure the manual is loaded with descriptive information, but without a solid background form either college or trade school, you're going to have a e The Federal Communications Commission won't let you near a difficult time of it. Passing the GROL examination might be board like this without a license. uncertain for beginners without any technician experience. There's a lot to know and I studied for the exam for well over a phrases as "Come in Steve." year in my spare time. Kaufman's book reads like an encyclo- Once contact is established on channel 16 or 2182 kHz, you pedia so don't expect to assimilate it all by just reading must switch to an appropriate working frequency for further through it once. communications. You may only use channel 16 and 2182 kHz for calling and in emergency situations. The actual communi- R &R's a Must cations should take place on a working frequency, "chit- The importance of knowing FCC rules and regulations and chat" is not permitted. You must choose the correct working radio operating procedures should not be underestimated. channel for the type of communications you wish to engage You could know all the electronics in the world, but without a in; either ship -to -ship, ship -to -coast station, public corre- solid foundation in the R &R's and proper operating pro- spondence, commercial communication, or intership safety cedures, the probability of passing the exam is slim. A on coast guard channel 6, etc. complete R &R listing is available from the FCC, and you may wish to order them directly: International Transcription Taking the Test Service, Inc., FCC Rules and Regulations, Suite 140, 2100 You must Pass a written examination of 100 multiple - M Street, N.W., Washington, DC 20037. Tel. choice type questions covering elements I, 2, and 3. You 202/857 -3800. $20.00 for Domestic R &R, $25.00 for Inter- must answer at least 75 percent of the questions correctly to national R &R. pass the examination. All elements (those being elements 1, 2, and 3) must be passed; there is no partial credit, like Maritime Info passing I and 2, but failing element 3. The 100 question test The following are some of the FCC rules you will need to contains a mix of all three elements and it's your total final know and a sample FCC type exam question. There are two score that counts, 75 and above passes. Should you fail the frequencies which are internationally designated for use by test you must wait at least two months before you're eligible the maritime radiotelephone stations in distress. The medium for another examination. frequency (MF) distress channel is 2182 kHz and the very All FCC field offices publish an exam schedule, you can high frequency (VHF) distress channel is 156.8 MHz (also request that list, which gives the examination dates and final known as VHF marine channel 16). Those are the same two filing date for each exam. The examinations are conducted frequencies which are used for intership call and reply, (FCC quarterly, that is, four times a year. rule 80.369). It is illegal to use selective calling on 2182 kHz Examinations are conducted by appointment only. Contact or 156.8 MHz (channel 16). Selective calling uses code your nearest FCC field office to request an application (form signals that are transmitted so that only a specific receiving 756). The office must receive your completed application by station will receive that transmission. For example, CTCSS the final filing date. There is no application fee. or continuous-tone coded sequelch system is not allowed. A week before the exam date you will receive an Admit- And, except when making a distress call, it is illegal to tance Pass stapled to your original 756 form, on which you transmit a general call on these frequencies; that is, a com- will find all the information you will need like date, time, munication not addressed to a particular station or group of place, examination type -GROL, etc. You may use a regular stations, (FCC rule 80.89). Now lets try test question, Q5. calculator during the test, however, pocket calculators containing programmable Q5: What two frequencies in the maritime mobile service are memories, magnetic card memories, used for distress traffic, and for calling intership communica- or printing calculators are prohibited. Also, bring proper identification, tions before moving to a working channel. like a drivers license, because you must prove that you are the a. 2182 MHz c. 156.8 MHz applicant whose name is written on the Admittance Pass. b. 2182 kHz d. 156.8 kHz The actual examination e. Both b and c procedure is rather straight forward. You're handed the GROL exam and a sheet of scrap The correct answer to question Q5 is (e). That is how you paper for calculating your answers. During my exam which make an intership (ship to ship) call. Turn your radi- started at 8:45 a.m. there were about 50 persons taking the otelephone on and listen on the appropriate distress and exam. The room was very quiet and everyone was anxious to calling frequency, Channel 16 or 2182 kHz, to make sure it's get started. We were all there for one reason, to get our FCC not being used. If it is clear, put your transmitter on the air. license. About 3 -Y2 hours after I started the test, I completed That is usually done by depressing the "push to talk" button the last question. The one terrific aspect of the exam pro- on the microphone. Call the vessel you wish to communicate cedure is they mark your test and tell you on the spot if you with by using its name; then identify your vessel with its passed or failed. I hope everything goes well for you if you name and FCC -assigned call sign. Do not add unnecessary decide to go for your license. Good luck. 90 M.M INCIUaNG N 11-PAGE

THE MAGAZINEectionics FOR THE ELECTRONICS ACTIVIST! TROOPER -PROOF HIDE -AWAY RADAR Build the... DETECTOR SYSTEM Meal being hm..w by tmeeme DIGI -LYZER IC TESTER writ, the sure morns. desk.' Ourckly 0.0, uu. quls110r1able IC's a logic circuit you can contrdt BUILD THE GEE -WHIZ BADGE SM Page 42. Summer you con..rxbn rlrwMr web ocikeslale chase tights Every

~~TV RECEPTION IN MOUNTAINOUS REGIONS IIOw to OR. nASdbn. dlblclion ait imstlsr b Pvb in .IprM Ktbal(a~~

COMPUTERS YOU CAN HAVE THE NEXT TWELVE IS- AND NAM RADIO PLUS- SUES of Hands -on Electronics delivered to Old end new t.cfrolosem romp. The VOX Box pukes a comeback! to add now mid1MwaR ban old hobby your home for only $18.95 saving $11.05 off How made the 4-megabit RAM chip' - they Reintroducing the all-0and leid strength meter the single copy price. d New Unusual chassis IOr the protect builder! lad( illsLs Ibis Iva* Plus much much more' III. IN EVERY ISSUE OF Hands -on Electronics will continue to contain a variety of construction IF YOU'RE THE KIND OF READER that articles to suit every taste. In addition, feature doesn't want to wait, you can order your next articles on electronics fundamentals, test equip- copy of Hands -on Electronics now. Hands -on ment and tools will round out each issue. Of Electronics is crammed full of electronic proj- course, Hands -on Electronics will continue to ects that you won't be able to wait to build for provide new product and literature listings to yourself. You can expect top -notch digital proj- keep you up to date on the latest developments ects, fun -to -play electronic games, valuable in electronic technology. add -on computer projects, BCB and shortwave receivers, photographic /darkroom gadgets, de- GET IN ON THE ACTION! Order your next vices to improve your car's performance, test issue of Hands -on Electronics today. Use the equipment ideas, and more in every issue of convenient order coupon below. Be sure to send Hands -on Electronics. check or money order -no cash! kam Hands -on Electronics SUBSCRIPTION

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91 UTILITY SOFTWARE ones, expensive ones, small ones, large ones, and (Continued from page 58) some that are really full -scale programs in themselves. We don't necessarily recommend any of them for every- ENCRY, figuring that anything on encryption had to one; the whole idea of this special feature was simply to include those letters. (Seekeasy is not case sensitive.) In show the broad range of utilities that are available; the less than the blink of an eyes SEEKEASY provided the kind that take some of the drudgery out of personal five quotes shown in Fig. 27. computing. And most important, examples of the kind Now the first match is rather obvious, because it's of computing power available to the non -hacker, ap- about encryption. But how did the others get there? plications- oriented user. If you have a favorite we've Well, in the second listing the first word, science, has overlooked, please write and tell us so. If it appears to the letters ENC, which is close to ENCRY, so Seekeasy have broad appeal we'll try to cover it the next time we said "that's close enough." do a special section on utilities. Similarly, the third listing has the word difference, again ENC, while the forth listing has patience, again ENC. The fifth listing has the name Lawrence, again ENC. Seekeasy will list up to 100 entries, with the closest match for the entered search word or characters at the top of the list. Sometimes you might wonder how in the heck it finds anything, but it does because it seeks out the closest match possible. For example, if the keyboarded search word is RASPUTIN, in my database of quotes the first one listed will be "FISH AND VISITORS STINK IN THREE DAYS - Benjamin Franklin." Now where does that quote fit the search word RASPUTN? Simple, it's the IN at the end of RASPUTIN. The quote itself has the word "IN," and there's an IN in the word "Franklin." See how hard Seekeasy tries for a match?

~~Summing Up Well, we've given you a smorgasbord of utilities: free "Let's see you shoot the Apple!"~~

E -Z MATH Subtracting the exponents: (Continued from page 73) 1W-7= 10-4 L = 2.23 x 10-4 Henries ohms is 3.6 x I0; = 3600 ohms. The K is replaced with IO' or 1000. A value of 1.5 megohms is 1.5 x 106 or 1,500,000 Coil values are usually given in millihenries (mH) or ohms. The meg is replaced by multiplying by 106 or microhenries (i.H). Let's use p.H here. Micro (II) is one 1.000.000. millionth so the power of 10 must be 10-6. We then adjust the Now consider the formula for computing the inductive numerical value accordingly. reactance (X1) of a coil (L) at a specific frequency (f). L = 2.23 x 10-4= 223 x 10.6 XL =6.28 IL L= 223 p.H

Remember, we must use basic units: reactance in ohms, The formula for computing capacitive reactance is: frequency in Hertz (Hz), and inductance in henries (H). = l/6.28fC Suppose we want to compute the coil value at a given fre- X quency for a desired value of reactance. To do this, we (Continued on page 94) rearrange the formula. Electronic Calculators L = XL/6.28f Electronics math is infinitely faster and easier if you use a calculator. Any standard, inexpensive, four-function (add, Now, what value inductance will give us a reactance of 7K . subtract, multiply, and divide) calculator will do. A square- ohms at a frequency of 5 MHz? First the Xi must be ex- root function is also highly desirable since it is such a com- pressed in ohms, 7K = 7,000 or 7 x 10; ohms. The frequency mon electronic math operation. is 5 MHz or 5 megahertz. That is 5,000,000 or 5 x 106 Hz. The best calculator for electronic calculations is a scientific The computation looks like this: calculator. If you plan to do much electronic math, then by all means get one. Here are the features you should look for: L = 7 x 103/6.28(5 x 106) Scientific notation; Trigonometry functions (sine, cosine, L= 7x103/31.4x106 tangent); Logarithms; Exponentials (XY, 10Y, ex, etc.); Square and square root Even sophisticated calculators with L = 7 x10313.14 x107 these functions are relatively inexpensive. You should be able Dividing the values: to get one for less than $20. It will save you lots of time and make all calculation faster and easier. 7/3.14 = 2.23

9 2 This will be HOW YOU AND THE COMPUTER CAN BE FRIENDS... coming to you Getting Started Programs, Circuit when you Design, Games A/D -D /A Interfacing subscribe to Peripheral Equipment Radio -Electronics ' CONTROL YOUR HOME NEW AUDIO DIMENSIONS FOR YOUR PLEASURE... BY TELEPHONE $2.25 JUNE 1987 R io- Noise -Reduction Devices HELPFUL How to Connect that CONSTRUCTION Extra Add -On ARTICLES... Hi -Fi Accessories Test Equipment New Technology TECHNOLOGY - VIDEO - STEREOrnnïnn. - COMPUTERS - SERVICE Hi -Fi en Accessories Telephone Accessories TV WONDERS FOR YOUR Music Synthesizers FUTURE... Computer Equipment BUILD A Latest Receivers and Automotive Equipment Circuits Intruder Alarms - DIGITAL The Home Entertainment Home E Car DASHBOARD Center Video Accessories Add a tachometer Projection TV to your car - ' Satellite TV Receivers NEWS ON NEW Jack Darr's Monthly TECHNOLOGY Service Clinic Computers NEW LIFE FOR. Service Problems and Microprocessors OLD CAR RADIOS Solutions Satellite TV Convert them to receive shortwave! Teletext REGULAR MONTHLY FEATURES Automotive Electronics BUILD THE R -E ROBOT DESIGNERS NOTEBOOK Speech Synthesizers Adding the control board. by Robert Grossblatt IC Applications HOBBY CORNER by "Doc" Savage, K4SDS FASCINATING FLIP FLOPS STATE -OF-SOLID -STATE "HOW TO DO IT" A circuit cookbook by Bob Scott ARTICLES... WHAT'S NEWS, new Build Your Own products. stereo news PLUS: Projects Designing PC boards and NEW IDEAS, STEREO Make Your Own PC on your computer * Audio Update * Video News PRODUCTS, NEW Boards COMPUTER PRODUCTS Wiring Techniques * New Ideas * Antique Radios FOR HOME/JOB and Soldering and * Satellite TV * New Products MUCH MORE! Desoldering * PC Service * Ask R -E Design and Prototyping

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When you select one of the subscription offers listed on the handy coupon -you'll be assured of having your copy reserved, even if it sells out on the newsstand. Make sure you get all the excitement in every issue of Radio -Electronics, every month, by filling in and mailing your subscripton card today. 93 (Continued from page 92) Practice Problems 16-18 where X, is in ohms, f is in Hz and C is in farads. What is the The following will test all you have learned. reactance of a .I -µF capacitor at 20kHz? 16. Use Ohm's law (I = V /R) to find the current in a circuit First, we convert to basic units: where the voltage is 150 volts and the resistance is 3 .110= .1 x 10-6F and megohms. Express the current in microamperes. 20kHz = 20 x 103 Hz 17. Find the power (P = I222R) in a circuit where:

~~Therefore, I = 70 mA and R =15K ohms.~~

X = 1/6.28(20 x I03)(. I x 10-6) Express the power in watts. X = 1/12.56 x 10-3 18. At what frequency (f) does a tuned circuit resonate with X, = .0796 x 10' an inductance (L) of .0015 p.F? Express the frequency if you X,- = 79.6 ohms can, in kHz.

6. 9500 13. x 103 Answers to Practice Problems 7.62 7. .000000003303 14. 3,26 x 105 1. u) 103=1,000 b) 10-6 8. 830 x 103 15. 2.23 X 10-2 b) 109 = 1,000,000.000 c).2x103 9. .015 x10-3 16. 50µA 2. a) 10-6= .000001 d) .25 x10-7 10. 6.923 x 10-1 17. 73.5 watts b) 10-12 = .000000000001 4. 9.1 x 108 11. 1.62 x 104 18. 29.072 kHz 3. a) 102 5. 8.25 x10-9 12. 4.84 x 10-8

BUILD A MAXWELL INDUCTANCE BRIDGE Connect an inductor to the bridge binding posts and turn the (Continued from page 32) dials, listening for a null. If no null is found, try other settings of the range switch and keep looking for the null. As the null positions of the RANGE switch, SI, as indicated in Figure 2. is approached you will notice that the settings of the L and Q dials interact with each other; keep adjusting first one and Accessories then the other until the deepest null is found. If you don't already have a 10kHz sinewave oscillator, Fig. As the volume of the tone gets less and less, keep increas- 3 shows a schematic of one you can build on a piece of ing the amplitude of the oscillator output so you can pinpoint perforated circuit board. The 1000 -ohm trimpot must be the null better. When finished with the adjustments, multiply adjusted for the best sinewave output, using an oscilloscope. the reading of the L dial times the setting of the range switch You should be able to get about 6 volts peak -to -peak of to find the inductance. For example, if the range switch is set sinewave amplitude at the output before clipping starts. at .01 henry; and the L dial reads 8, the inductance value is A small audio amplifier may be of value between the .08 henry; or 80 milihenries. bridge and the headphones to bring up the volume near the The Q of the inductor is read from the Q dial. Keep in mind null point. Or the reader may wish to install a power amplifier that that is the value of Q at I kHz; Q can have quite a different and loudspeaker to hear the audio tone. If so, be sure to keep value at a much higher or lower frequency. A I -µH RF choke

the amplifier circuit completely isolated from the oscillator might have a Q of 2 at I kHz, but its Q at 1 MHz could be in circuit. If their grounds were common, for example, part of the range of 50 to 100. the bridge would be short- circuited. Expanding the Range Measuring an Inductor The next step in the project is to see if I can get the Maxwell Connect a 1,000 -Hz sinewave oscillator and a pair of bridge to work at higher frequencies and measure inductors headphones to the Maxwell bridge. Adjust the oscillator from one millihenry down into the nanohenry range. If not, amplitude control for a comfortable tone level in the phones. try adding a switch to select from different values of CB. You can expand this project as much as you like to obtain the

OUTPUT range that suits your needs. That's enough inducement for A now, enjoy the building R1 { the project and have fun. 15K 1/2 TL082 C1 7 .01` 3 1/2 TL082 U1-b PARTS LIST AMPLITUDE 4 R5 1 CONTROL FOR THE AUDIO OSCILLATOR 8 6805 U1 -TL082 dual FET opamp (Radio Shack 276 -1715) R2 xC2 R4 15K 01 10K R1, R2-15 -ohm, 1/4-watt, 1% metal film resistor (Radio R3, 1K C3 C4 Shack 271 -309) 1 .:: ..0 R3 -1000 -ohm trimmer potentiometer R4- 10,000 -ohm, audio -taper potentiometer WAVEFORM ADJ S1A S1Bp 11 R5- 680 -ohm, 1/4-watt, 5% resistor =1819 Cl, C2- .01 -µF disc capacitor C3, C4- 10 -p.F, 35 -WVDC electrolytic capacitor S1 -DPDT toggle switch I1 -28 -volt, 40 -mA pilot lamp #1819, (Radio Shack Fig. 3 -This sinewave oscillator will work perfectly with 272 -1119) the inductance bridge. The variation of resistance in 11 Bi, B2-9 -volt alkaline battery with current changes helps the circuit produce clean output.

94 SAXON ON SCANNERS frequencies, known call signs, locations, primary- operations frequency. Listen (Continued from page 87) etc. , is contained in the 6th Edition of The there during any type of severe weather, Top Secret Registry of U.S. Government natural disaster, or major environmental/ lice using two -way radios. Their badges Radio Frequencies. So far as we know, transportation accident. Ed says that and shoulder patches identify them as that large volume (containing details of many hundreds of stations are authorized being from the GSA, and he wonders more than eighty agencies) is the first time on that frequency and sometimes skip re- what that is and why nothing has ever information has been published about the ception brings in Red Cross activities been published concerning the frequen- GSA's communications system. The 192 - from across the nation. cies they use. page book retails for $17.95 (plus $2 Please send along scanner-related Actually, the GSA (General Services postage) from CRB Research, PO Box newspaper clippings, photos, ideas, ques- Administration, a federal agency) oper- 56 -GP, Commack, NY 11725. tions, reception reports, new frequencies, ates nationwide and has a large communi- Ed Mamoulian of Arvada, CO asks that and what- have -you. Our address is: Marc cations system. Among the many duties we remind scanner owners that the Amer- Saxon, Saxon On Scanners, Hands -on of this low- profile agency is guarding ican Red Cross (in all areas) relies heavily Electronics, 500 -B Bi- County Blvd.. about 8,500 federal buildings against upon 47.42 MHz as that organization's Farmingdale, NY 11735. crimes, such as vandalism and theft, riots, terrorism, or attacks upon government officials who work in those buildings. REPRINT Two of the more popular GSA frequen- BOOKSTORE cies are 415.20 and 417.20 MHz, al- ri SP1 Special Projects #1 (Winter 1980) .... $6.00 105 Radio -Electronics back issues (1985). $4.25 though there are many others in the VHF SP4 Special Projects #4 (Summer 1982) .. $6.00 (Jan. 85 not available) and UHF spectrum. A roster of the GSA's SP5 Special Projects #5 (Winter 1983).... $6.00 Write in issues desired SP6 Special Projects #6 (Spring 1983).... $6.00 104 Radio- Electronics back issues (1984)..$5.25 SP7 Special Projects #7 (Summer 1983) .. $6.00 (December 1984 issue is not available) FRIEDMAN ON COMPUTERS SP8 Special Projects #8 (Fall 1983) $6.00 Write in issues desired (Continued from page 80) SP9 Special Projects #9 (Winter 1984) $6.00 El 103 Radio -Electronics back issues (1983)....55.50 SP10 Special Projects #10 (Spring 1984) $6.00 (Jan., Aug., Dec. are not available) 111 Hands -On Electronics #1 $5.00 Write in issues desired manual is very boards. (The supplied E1 112 Hands -On Electronics #2 $5.00 102 Radio -Electronics back issues (1982) . $5.75 thorough on how to get the clock up and Li 113 Hands -On Electronics #3 $5.00 (Jan. is not available) running.) 114 Hands -On Electronics #4 $5.00 Write in issues desired 115 Hands -On Electronics #5 $5.00 153 Etch your own PC boards $3.00 115A Hands -On Electronics #6 $4.50 154 How to Repair VCR's $3.50 Almost a Perpetual Calendar 116A Hands -On Electronics (Jan -Feb '86) $4.50 155 IBM Typewriter to Computer $3.00 The SMT module, whose CMOS mem- 116B Hands -On Electronics (Mar /Apr '86) $4.50 125 Radio -Electronics Annual 1985 $5.95 ory is maintained by the computer's 5 -volt 116C Hands -On Electronics (May /Jun '86) $4.50 126 Radio -Electronics Annual 1986 $4.95 power supply, or internal lithium batteries Cl 1160 Hands -On Electronics (Jul/Aug '86) $4.50 156 How to Make PC Boards $2.00 116E Hands -On Electronics (Sep/Oct '86) $4.50 157 All About Kits $2.00 10 (which have a rated life of more than El 116K Hands -On Electronics (Nov '86) $4.00 150 Electro Importing Co. Catalog (1918) $5.95 years) when the computer is off, provides 1161 Hands -On Electronics (Dec '86) $4.00 159 Low Frequency Receiving Techniques time -keeping information: hundredths of 117 Hands -On Electronics back issues Building and using VLF Antennas $6.00 Ideas - 42 $3.50 seconds, seconds, minutes, hours, day, (1987) $3.75 160 New Circuits Write in issues desired 161 Descrambling (Feb., 1984) $3.00 date, month, and year. 150 TV Descrambler $3.00 162 Build Your Own Satellite TV Receiver $7.00 The date at the end of each month is E1187 Experimenters Handbook $3.95 163 Receiving Satellite TV $7.00 compensated for months with less than 31 152 8 -Ball Satellite TV Antenna $5.00 164 Modern Electrics (April, 1908) $3.00 Players days, and there is an automatic correction 107 Radio -Electronics back issues (1987) $3.25 165 How to Repair CD Disc $5.00 106 Radio -Electronics back issues (1986) $3.75 166 Collected Works of Mohammed Ullyses Fips for leap years. The only thing that it can't Write in issues desired (62 pages, April Fools Collection) $7.50 do automatically is correct for Daylight 187 Designing With ICS $4.00 Savings Time: twice a year you must move To order any of the items indicated above, check off the If you need a copy of an article that is in an issue we the time one hour forward or back. ones you want. Complete the order form below, Include indicate is unavailable you can order it directly from us. your payment, check or money order (DO NOT SEND We charge 50C per page. Indicate the issue (month & CASH), and mail to Hands- on- Electronles, Reprint De- year), pages and article desired. Include payment in Plug -in and Whoops! partment, P.O. Box 4079, Farmingdale, NY 11735. full, plus shipping and handling charge. Make checks The hardware installation of the clock/ Please allow 4 -6 weeks for delivery. payable to Gernsback Publications, Inc. calendar module is finished as soon as the clock snaps into its socket. There are no wires to solder, no jumpers to connect, ARTICLE nothing! Figure 2 shows the SMT clock/ calendar installed in the last ROM socket on an XT-clone motherboard. Notice that PAGES MONTH YEAR there is an empty ROM socket immediately to the right of the clock. @50C each TOTAL PRICE All that you have left to do after install- TOTAL PAGES ing the SMT module is to re- install the MAIL TO: Hands-on- Electronics All payments must be in U.S. funds adapters in their slots and program the Reprint Bookstore, P.O. Box 4079, Farmingdale NY 11735 SHIPPING CHARGES IN USA & CANADA The problem is, re- the clock. installing $0.01 to 55.00 $1.00 $30.01 to 40.00 ....$4.75 SORRY -WE ONLY adapters isn't as easy as it reads. I don't $5.01 to $10.00 $1.75 $40.01 to 50.00 .... $5.75 SHIP TO USA 8 CANADA know about IBM XT's or other XT- $10.01 to 20.00 $2.75 $50.01 and above ... $7.00 clones, but mine does not have enough 520.01 to 30.00 $3.75 Total price of merchandise S clearance above the ROM socket con- Sales Tax (New York State Residents only) S taining the clock/calendar module. Nor- Shipping Charge (see chart) S

mally, the bottom of the adapters just skim Name over the tops of conventional ROM's. Total Enclosed S Address There is no way to seat an adapter if the State Zip H 2-88 (Continued on page 97) City 95 HANDS -ON MARKETPLACE

PLANS /KITS BUILD this five -digit panel meter and square wave PROJECTI(IN- TV...Convert your TV to project 7 generator including an ohms, capacitance and fre- foot picture...Results comparable to $2,500.00 proj- CRYSTAL radio sets, plans, parts, kits. Catalog quency meter. Detailed instructions $2.50. BAG - ectors...Total cost less than $30.00... Plans and 8" $1 00 MIDCO, 660 North Dixie Highway, Hol- NALL ELECTRONICS, 179 May, Fairfield. CT lens $21.95...Illustrated information free. MAC - lywood. FL 33020. 06430. ROCOMA-HF, Washington Crossing, PA 18977. Creditcard orders 24 Hours. (215) 736 -3979. DJ beatmeter you can build. Organize your L.P.s by beats per minute like the pros do to make "mixing" CLASSIFIED AD ORDER FORM faster and and easier. Plans and instructions $2.00. LERCOM, P.O. Box 2274, Sta.1, Kingsville, TX To run your own classified ad, put one word on each of the lines below and send this form along with your check to: 78363. Hands-on- Electronics Classified Ads, 500 -B Bi- County Boulevard, Farmingdale, N.Y. 11735 SAVE money on IBM XT computers. Assemble them yourself! Complete tutorial video tape (VHS) for $17.95. money PLEASE INDICATE in which category of classified advertising you wish your ad to appear. For only Send check or order to B-G- TRONIC, P.O. Box 2231, Bloomfield, NJ 07003. special headings, there is a surcharge of $10.00. ( ) Plans Kits ( ) Business Opportunities ( ) For Sale VOICE disguisers! FM bugs! Telephone transmitters! Phone snoops! More! Catalog ( ) Education/Instruction ( ) Wanted ( ) Satellite Television $1.00 (refunda- ble): XANDI ELECTRONICS, Box 25647, 32J, ( Tempe, AZ 85282. Special Category: $10.00 ELECTRONIC Dowser-Book of theory and complete plans for sensitive Cryptesthesic. Galvanic in- PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS. strument, $10. NOVA SYSTEMS, 11208 -C Iron Oak Trail, Austin. TX 78750. (No refunds or credits for typesetting errors can be made unless you clearly print or type your copy.) Rates indicated are for standard style classified ads only. See below for additional charges for special ads. Minimum: 15 words.

Phone recorder control. Automatically records phone 1 2 3 4 5 conversations When receiver is lifted. Interfaces your phone to any tape recorder Meets all FCC requirements. Guaranteed to work Dealer Inquiries 6 7 8 9 10 Send 529.95 plus $3 shipping and handling welcome. (VISA, MASTERCARD, COD) to: ELECTRONIC DEVICES, 4900 87th Ave. N., Pinellas Park, FL 33565

11 12 13 14 15 ($21.00) CABLE EQUIPMENT 16 ($22.40) 17 ($23.80) 18 ($25.20) 19 ($26.60) 20 ($28.00) CABLEL -TV Secrets -the outlaw publication the cable companies tried to ban. HBO, Movie Chan- nel, Showtime, descramblers, converters, etc. Suppliers list included, $8.95. CABLE FACTS, Box 21 ($29.40) 22 ($20.80) 23 ($32.20) 24 ($33.60) 25 ($35.00) 711 -H, Pataskala, OH 43062.

26 ($36.40) 27 ($37.80) 28 ($39.20) 29 ($40.60) 30 ($42.00) CABLE TV DESCRAMBLERS CABLE TV converters. "NEW" Zenith Flash, Sci- entific Atlanta, Jerrold, Oak, Zenith. Hamlin. Many others. "NEW" VIDEO HOPPER "The Copy Kill- 31 ($43.40) 32 ($44.80) 33 ($46.20) ($47.60) 34 35 ($49.00) er". Visa, M C & Amex 1-800 -826 -7623. B &B INC., 10517 Upton Circle, Bloomington, MN 55431. We accept MasterCard and Visa for payment of orders. If you wish to use your credit card to pay for your ad fill in the following additional information (Sorry, no telephone orders can be accepted.): BUSINESS OPPORTUNITIES HOME assembly. Assemble PC boards for video Card Number Expiration Date accessories. We supply materials. No experience needed. $7.50 per hour. Send self- addressed, stamped envelope, to: MICRON ELECTRONICS, Box 4716, Akron, OH 44310. PRINT NAME SIGNATURE

IF YOU USE A BOX NUMBER YOU MUST INCLUDE YOUR PERMANENT ADDRESS AND PHONE TUBES - 2000 TYPES NUMBER FOR OUR FILES. ADS SUBMITTED WITHOUT THIS INFORMATION WILL NOT BE ACCEPTED. DISCOUNT PRICES! CLASSIFIED COMMERCIAL RATE: (for firms or individuals offering commercial products or services) Early, hard -to-find, and modern tubes $1.40 per word prepaid (no charge for ZIP code)... MINIMUM 15 WORDS. 5% discount for same ad in 6 Also transformers, capacitors and issues within one year; 10% discount for 12 issues within one year if prepaid. NON -COMMERCIAL RATE: parts for tube equipment. Send $2.00 (for individuals who want to buy or sell a personal item) $1.15 per word, prepaid....no minimum. ONLY FIRST for 20 page wholesale catalog. WORD AND NAME set in bold caps at no extra charge. Additional bold face (not available as all caps) 25c per word additional. Entire ad in boldface. $1.70 per word. TINT SCREEN BEHIND ENTIRE AD: $1.75 per ANTIQUE ELECTRONIC SUPPLY word TINT SCREEN BEHIND ENTIRE AD PLUS ALL BOLD FACE AD: $2.05 per word. EXPANDED 688 W. First St. Tempe, AZ 85281.602/894-9503 TYPE AD: $1.85 per word prepaid. Entire ad in boldface. $2.20 per word. TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD: $2.30 per word. TINT SCREEN BEHIND ENTIRE EXPANDED TYPE AD PLUS ALL BOLD FACE AD: $2.70 per word. DISPLAY ADS: 1" 21/4"-$160.00: 2" 21- $320.00; 3" 2' l'- $480.00 General Information: Frequency rates and prepayment discounts are available. ALL COPY SUBJECT TO PUBLISHERS APPROVAL. ADVERTISEMENTS USING P.O. BOX ADDRESS WILL NOT BATTERIES BE ACCEPTED UNTIL ADVERTISER SUPPLIES PUBLISHER WITH PERMANENT ADDRESS AND PHONE NUMBER. Copy to be in our hands on the 18th of the third month preceding the date of issue HARD to find sizes Lithium Gelyte Nicad custom (i.e.; Aug. issue copy must be received by May 18th). When normal closing date falls on Saturday, Paks discount prices: call or write BATTERY TER- Sunday or Holiday, issue closes on preceding work day. Send for the classified brochure. Circle MINAL, 2492 Merrick Road, Bellmore. New York Number 49 on the Free Information Card. 11710. (516) 679 -8600.

96 FOR SALE FRIEDMAN ON COMPUTERS ADVERTISING INDEX (Continued from page 95) PC -XT /AT clone bare PCB, wholesale. INTEGRITY TECHNOLOGY, 105 Serra Way, Suite 230, Milpitas, HANDS -ON ELECTRONICS magazine not any responsibility for CA 95035. does assume clock/module is installed because it's a errors that may appear in the index below. CANADIANS send for free price list. DG ELEC- smidgen higher than a conventional TRONICS, P.O. Box 312, Montreal, P.O. H4A 3P6. Free Information No. Page ROM; and the adapter certainly can't be 2716/58/32132A EPROM programmer. Plans and 6 Sales 22 a ROM piggybacked on two additional projects plus hardware bonus! $2.50 AMC installed if there's plus $1.00 S /H. GALLIUM JUNCTION, 540 -C N.E. 5 All Electronics 14 the clock/calendar. Northgate Way, Ste. 542, Seattle, WA 98125. The thing to do is to use a short, or a Amazing Devices I2 TUBES (radio). New in original cartons. Also many half-size adapter in the slot in front of the used types. Parts, collectables. LSASE for lists. Antique Electronic Supply 96 In DIERS, 4276 -H North 50th Street, Milwaukee, WI socket containing the SMT module. 53216 -1313. I1 CIE II my case, I used the original short serial THE DECODER. A national monthly technical Computer Continuum 18 adapter from my IBM /PC in the slot. If all newsletter covering satellite and cable TV de- 12 your adapters are full size, you'll have to scramblers. $18.00 /year. Sample $2.00. Video - 7 Cook's Institute install the SMT module on one of the Cipher II Manual-$120 pages...$29.95. Oak Orion s Digi-Key 5 Nanual-120 pages...$29.95. Schematics and soft- daughterboards, piggybacking a daugh- ware catalog...$1.00. Satellite and video equipment Elec. Industry Association 25 catalog $2.00. TELECODE, P.O. Box 6426, Yuma. terboard ROM on the clock module. AZ 84364 -0840. Electronic Devices 96 EPROM emulator /programmers. Free info sheet. Electronic Tech. Today CV3, 16, 24 Software Programming SOLICON, 8825 El Matador Dr., Gilroy, CA 95020. 12 Electronics Book Club 3 The clock /calendar nodule is supplied P OCKET knives! Heavy duty utility knife with ten with software for both the IBM- and Ap- blades $12.00 + $1.00 S /H. Free catalog GREENO Elephant Electronics 13 Box 20891, N.Y. NY 10023. ple- compatible computers. The IBM soft- SUPPLY, Col. of Engineering .. 23 - Grantham ware consists of two programs: one to - Heath 15 initialize the clock- meaning it puts the - ISCET 22 date and time into the clock's memory; the 9 MCM Electronics 17 other program sets the computer system's CABLE T.V. the SMT module. McGraw Hill (CED) 83 clock from - Normally, you enter the date and time NRI 21 "BOXES" - from the keyboard into the computer sys- Converters -Descramblers - Pacific Cable 7 tem. When using the SMT clock, the soft- Remote Controls - Accessories Io Regency CV2 ware automatically answers the TIME? * Guaranteed Best Prices * - Seattle FilmWorks CV4 and DATE? queries with the data from the * 1 Year Warranty-- C .O.D's clock/calendar. Actually, that's an * Trans World 97 SMT * Immediate Shipping * - oversimplification. The TIME? and * FREE CATALOG * DATE? entries aren't prompted. The SMT Call or Write. software simply copies the clock/calendar TRAN$-WOf11LD CABLE CO memory. NC 63, Box 531 data into the appropriate Pequot Laker MN 58472 The proper way to handle entering the (218) 543 -41eT1 - 1 date and time is to make the supplied XTCLOCK.COM (set clock) program part of your AUTOEXEC.BAT file. In COMPUTERS that way, the date and time are automatically loaded into the system when the COMMODORE repair. $39.95 for C -64. Oldest/ MOVING? largest authorized repair center in the U.S. Fast computer is first booted. turnaround...."Commodore Diagnostician". A com- If you have ever used a clock/calendar plete diagnostic reference chart for fixing Com- Don't miss a modore computers. Over 4,000 sold. $6.95 plus adapter of any kind, you'll be surprised to postage....HD C -64 power supply $27.95....VISA/ single copy of find that the SMT module doesn't have MC...KASARA MICROSYSTEMS, INC., 31 Murray Hands -on Elec- some kind trimmer adjustment to Hill Drive, Spring Valley, NY 10977, (800) 642-7634, of (800) 248-2983 (outside NY) or (914) 356 -3131. tronics. Give us: ATTACH "zero" (correct) the time. All clock used seem to COMMODORE chips at low prices. Quantity prices LABEL adapters that I've before drift of any two or more: 6510 -$8.95, 6526- $8.95, a few minutes every month unless the 6567- $14.45, 6581- $10.95, 825100- $10.95, Six weeks' notice HERE 901225/226/227 -$9.95 and many, many trimmer is properly adjusted. others...VISA/MC..KASARA MICROSYSTMES, Normally, I prefer to fuss with the trim- INC., 31 Murray Hill Drive, Spring Valley, NY 10977, Your old address mer once or twice because I don't like (800) 642 -7634, (800) 248 -2983 (outside NY) or and zip code (914) 356 -3131. fussing with most clock- setting software -they require too many entries and Your new ad- MASTERCARD AND VISA are now accepted procedures. The SMT clock -which for payment of your advertising. Simply dress and zip doesn't have a trimmer-drifts about a complete the form on the first page of the code L -J minute a month. I don't miss the trimmer Market Center and we will bill. because all it takes is IBM's original TIME entry to correct the SMT clock. does the THIS IS A BOLDFACE EXPANDED -TYPE AD name (please print) The SMT software automatically a WITH A TINT SCREEN. See how it jumps out reset without my answering string of on the page. To order your ad in this format address questions. The SMT clock is priced at $49 calculate the cost at $2.70 per word. at some computer equipment distributors. It can also be purchased direct from SMT city state zip cods (1145 Linda Vista Dr., San Marcos, CA. Mail to: Hands-on Electronics 92069) for $49.00, plus postage and han- SUBSCRIPTION DEPT., P.O. BOX 338, dling. For more information circle No. 52 BUY BONDS Mt. Morris, IL 61054 -9932 on Free Information Card. 97 ANTENNA CARR ON HAM RADIO (Continued lrom page 79)

dial. The reason is that the band - MHz the main 330 MHz 3 -30 ® 23 MHz ®23 MHz 455 kHz spread capacitor tuned a much smaller segment of the spectrum. 8 Figure shows the bandspreaded tun- FLO ing circuit. Inductor LI is the only induc- VFO tor in the circuit. There are, however, CRYSTAL 5.455- several capacitors (Cp and C, are the pad- OSC. 6.455 MHz der and trimmer capacitors used to im- is the main prove tracking). Capacitor CI BANDSWITCHQ Q tuning capacitor, and makes up the major- I1 I1 ity of the capacitance in the circuit. The 00 00 bandspread dial is connected to a smaller T T2TT variable capacitance, C2. A In normal operation, the bandspread capacitor is set to either maximum or minimum capacitance, and a SET mark appears on the dial to indicate that point. C4 The main dial is then set at one end of the MAIN TUNER band of interest, usually to a specific cal- i ibration point marked on the dial. Some- times, an internal or add -on 100 -kHz or B Fig. 9 modern receivers use double- conversion (as shown in "A "). But, by 1000 -kHz crystal calibrator was used to -Many using a circuit like the one shown in "B," we can linearize the dial markings. assist the operator in finding the correct point. In that type of radio, there are two dif- (PLL) controlled, rather than just crystal MAIN DIAL BANDSPREAD DIAL ferent frequencies. The first of those (IFI) controlled. will tune a certain frequency range, such In addition, the VFO is a PLL. The as 2 to 3 -MHz. The LO converts that fre- tuning control is not a capacitor, but rather quency range to 455 -kHz in a manner a digitally- encoded drum (or similar similar to any single -conversion receiver. mechanism) that is varied by the tuning The shortwave frequencies (3 to 30 -MHz) knob. The encoded drum produces a bin- are down -converted to 2 -3 MHz. Thus, all ary word that controls the phase -locked bands have equally- spaced bandspread- loop's divide -by -N converter. ing. Furthermore, by using a circuit like the one shown in Fig. 9B, we can linearize Future Topics the dial markings. In an upcoming column, we'll review a There are several capacitors in Fig. 9B, simple and low-cost station accessory that some of which have functions similar to will allow you to cut through the QRM on Fig. 8-In this bandspreaded, tuning those of other figures. In this case, today's crowded bands. Another upcom- circuit, Lt is coupled with several capac- however, the main tuning capacitor has a ing issue will discuss how to check the itors (Cp and Ct are the padder capacitance range that is only a small per- operation of 2 -meter (and higher band) and trimmer capacitors used to improve centage of the total capacitance used to FM transceivers. tracking). Capacitor Cl makes up the resonate the inductor (LI). If that capaci- As always, you are invited to send your majority of the circuit capacitance. tor is a straight -line frequency type, then tip, suggestion, photos to Joe Carr, linearity is even further improved. K41 PV, at PO Box 1099, Falls Church, On some receivers, the bandspread dial The most modern double or triple -con- VA 22041. was calibrated with the amateur -radio version receivers replace the variable fre- band frequencies. On all other radios, in- quency oscillator (VFO) of Fig. 9A with a cluding the "ham" types, a LOGGING digitally- synthesized oscillator to tune the SCALE (0 to 100) was provided to help same range. The synthesizer uses a phase - relocate specific frequencies or stations. locked loop (PLL) to force the output of a Once the main dial was correctly ad- voltage -controlled oscillator (VCO) to justed, the bandspread dial was used to operate on a fixed multiple of a crystal - tune in stations. controlled reference oscillator. If that ref- At one time ham -band only receivers erence frequency is small enough, then were designed like general-coverage re- we can smoothly tune the entire range. ceivers with one exception. Most of the capacitance in the tuning circuits was in Modem Designs the fixed capacitors and trimmers, while Modern radio receivers used in amateur the "main tuning" control was what receivers, and by shortwave listeners, use would be the bandspread capacitor in gen- digital readouts. Most of those designs are eral- coverage receivers. simply double- conversion receivers similar to the illustration above. The convert- Double Conversion Design er section that down- converts (or in some Many modern receivers are double - designs up- converts) the ham -band signal conversion models, as shown in Fig. 9A. to the "variable IF" is phase- locked loop "Battery's low -got a mini jumper cable ?"

~~98 r 7 Electronics Paperback Books GREAT ELECTRONICS PAPERBACKS FROM ETT~~

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BP125 -25 SIMPLE AMATEUR BAND ANTENNAS $5.00. All are inexpensive BP33-ELECTRONIC CALCULATOR USERS HANDBOOK $5.75. Invaluable 'to build, yet perform well Diodes, beams, triangle and even a mini rhombic book for all calculator owners Tells how to the most your get out of calculator BP128-20 PROGRAMS FOR THE ZX SPECTRUM AND 16K ZX82 $5.75. BP36 -50 CIRCUITS USING GERMANIUM, SILICON 8 ZENER DI- Included with each program is a flow chart and a description of what happens. ODES $5.00. A collection of useful circuits you II want in your library Notes for converting programs for use on other computers are also included.

BP235 -POWER SELECTOR GUIDE $10.00. Complete guide to semiconduc- BP37 -50 PROJECTS USING RELAYS, SCR'S 8 TRIACS $5.00. Build pri- tor power devices More than 1000 power handling devices are included They are ority indicators. light modulators. warning devices, light dimmers and more tabulated in alpha -numeric sequency. by technical specs. Includes power diodes. Thyristors. Macs. Power Transistors and FETS BP39 -50 FET TRANSISTOR PROJECTS $5.50. RF amplifiers. test equipment. tuners. receivers. tone controls. etc BP234- TRANSISTOR SELECTOR GUIDE $10.00. Companion volume to BP235. Book covers more than 1400 JEDEC. JIS. and brand -specific devices Also LED A large contains listing by case type, and electronic parameters. Includes Darlington BP42-SIMPLE CIRCUITS $5.00. selection of simple applications for this simple electronic transistors. high- voltage devices high- current devices. high power devices. component

BP99 -MINI- MATRIX BOARD PROJECTS $5.00. Here are 20 useful circuits BP127 -HOW TO DESIGN ELECTRONIC PROJECTS $5.75. Helps the reader that can be built on a mini-matrix board that is lust 24 holes by ten copper -foil strips. to put projects together from standard circuit blocks with a minimum of trial and error BP157 -HOW TO WRITE ZX SPECTRUM AND SPECTRUM GAMES PRO- A -clear GRAMS $5.95. crystal step -by -step guide to writing your own graphics BP182 -MIDI PROJECTS $6.95. Midi interface permits computer control of games programs musical instruments

BP117- PRACTICAL ELECTRONIC BUILDING BLOCKS-Book 1 $5.75. BP92- CRYSTAL SET CONSTRUCTION $5.00. Everything you need to know Oscillators. Timers, Noise Generators. Rectifiers. Comparators. Triggers and more. about building crystal radio receivers BP184 -INTRO TO 68000 ASSEMBLY LANGUAGE $6.50. The 68000 is a great new breed of microprocessor Programming in assembly language increases BP45- PROJECTS IN OPTOELECTRONICS $5.00. Includes infra -red detectors. modulated light the running speed of your programs. Heres what you need to know. transmitters. transmission and photographic applications

BP179- ELECTRONIC CIRCUITS FOR THE COMPUTER CONTROL OF BP48- ELECTRONIC PROJECTS FOR BEGINNERS $5.00. A wide range of ROBOTS $5.00. Data and circuits for interfcing the computer to the robots easily completed projects for the beginner Includes some no- soldering projects motors and sensors POPULAR BP126 -BASIC 8 PASCAL IN PARALLEL $4.95. Takes these two program- BP49- ELECTRONIC PROJECTS $5.50. Radio. audio. household and test equipment projects are all included ming languages and develops programs in both languages simultaneously.

224-50 CMOS IC PROJECTS $5.25. Includes sections on multivibrators. BP174 -MORE ADVANCED ELECTRONIC MUSIC PROJECTS $6.95. In- amplifiers and oscillators, trigger devices, and special devices. cludes items like flangers, phasers. mini-chorus. percussion synthesizers and more 225-A PRACTICAL INTRODUCTION TO DIGITAL IC'S $4.95. Mainly con- cerned with TTL devices. Includes several simple protects plus a logic circuit test BP56- ELECTRONIC SECURITY DEVICES $5.00. Includes both simple and set and a digital counter timer more sophisticated burglar alarm circuits using light infra -red. and ultrasonics

BP170- INTRODUCTION TO COMPUTER PERIPHERALS $5.95. Shows how BP59- SECOND BOOK OF CMOS IC PROJECTS $5.00. More circuits show- to use a variety of co computer add -ons in as non -technical a way as possible ing CMOS applications Most are of a fairly simple design

227- BEGINNERS GUIDE TO BUILDING ELECTRONIC PROJECTS $5.00. BP72 MICROPROCESSOR How to tackle the practical side of electronics so you can successfully build -A PRIMER $5.00. We start by designing a small electronic projects computer and show how we can overcome its shortcomings

BP169-HOW TO GET YOUR COMPUTER PROGRAMS RUNNING S5.95. BP74- ELECTRONIC MUSIC PROJECTS $5.95. Provides the experimenter Shows how to identify error in program and what to do about them. with a variety of practical circuits including a Fuzz Box. Sustain Unit. Reverberation BP194- MODERN OPTO DEVICE PROJECTS $6.25. Crammed with great Unit. Tremelo Generator and more projects for the experimenter. Includes sections on Fiber optics, passive Infra -Red detectors. plus an assortment of miscellaneous projects BP91 -AN INTRODUCTION TO RADIO DXING $5.00. How you can tune in on those amateur and commercial broadcasts from around the world in the comfort of BP180- ELECTRONIC CIRCUITS FOR THE COMPUTER CONTROL OF your home MODEL RAILROADS $6.25. Its easy to interface home computers to model railroad control The main problem is in interfacing the computer to the system BP94- ELECTRONIC PROJECTS FOR CARS AND BOATS $5.00. Fifteen BPI10 -HOW TO GET YOUR ELECTRONIC PROJECTS WORKING $5.00. simple projects that you can use with your car or boat All are designed to operate How to find and solve the common problems that can occur when building projects from 12 -volt DC supplies

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S5 01 to $10 00 . $1.75 Total price of merchandise $ Name $10 01 to 20 00 . $2.75 $20 01 to 30 00 $3.75 Sales Tax (New York State Residents only) $ Address $30 01 to 40 00 $4.75 Shipping (see chart) $ City State Zip $40 01 to 50 00 $5.75 All payments must Total Enclosed $ . H 288 $50 01 and above $7 00 be in U.S. funds J THE PERFECT 3$mm TRAVEL FILM Prints and Slides from the same roll Introducing the 35mm color film that's designed for travel photography. It's the same film Hollywood producers choose for location shoots all over the world-Kodak's professional 35mm Motion Picture film. Now, Seattle FilmWorks has adapted it for use in your 35mm camera. Its wide exposure latitude is perfect for everyday shots. You can capture special effects, too. Shoot it in bright or low light-at up to 1200 ASA. It's economical to shoot and process. And, Seattle FilmWorks lets you choose prints or slides, or both, from the same roll. Try this remarkable film today! MI- MI -- =- MN --- =- MN MN - -INM ' -` $2 INTRODUCTORY SPECIAL 1:1 RUSH me two 20- exposure rolls of Kodak MP film for my 1 _ 35mm camera. Enclosed is $2 for a 2 -roll starter pack including I I Eastman 5247® and 5294.® 100% Satisfaction Guaranteed. I NAME

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