Popular R I Jim Build a 0011110 Welcome Trick -Or- Treaters Greeter with Spooky Sights and Sounds This Halloween

A HALLOWEEN TREAT FOR TRICK-OR-TREATERS

Oc tober 1996 Popular r i Jim Build a 0011110 Welcome trick -or- treaters greeter with spooky sights and sounds this Halloween

Usiug Digital Panel Meters Learn how to make your next project more accurate and attractive

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AmericanRadioHistory.Com OCTOBER 1996 Popular Electronics Vol 13, No. 10 A GERNSBACK PUBLICATION

C O V E R S T O R Y

31 Build the Goblin Greeter This Halloweer, why not greet trick -or- treaters with a special treat of your own? With the Goblin Greeter installed, every time someone rings your doorbell, he or she will be welcomed to your abode by a spooky, hologram -like phantom and haunting noises. The circuit can also be used indoors to provide your next Halloween party with a frightfully fun host -D. Derek Verner

C O N S T R U C T I O N Page 31 56 Build a Delayed Sweep Adapter This simple, plug -in circuit will increase the capabilities and performance of your scope. For less than $30, the Adapter lets you add a delayed sweep to just about any oscilloscope you choose. That saves you the added cost of buying an oscilloscope with the feature built -in -Skip Campisi

F E A T U R E S

39 Using Digital Panel Meters Page 45 Here are some great applications for digital panel meters that you can use as stand -alone units or as springboards for your own cicuit designs. Once you know how to work with DPMs, you'll be able to increase the accuracy of the next project of yours that requires a display, and give it a more attractive, professional look -Bill Stiles

45 Radio Amateurs Just who are hams and what do they do? There seem to be more than a few misconceptions about the amateur -radio hobby and its practitioners. Learn the truth in this panoramic look at radio amateurs, and see just how easy it is to become a ham yourself -Karl T. Page 56 Thurber, Jr.

POPULAR ELECTRONICS (ISSN 1042. 170-XI Published monthly by Gernsback Publications, Inc. 500 Bi- County Boulevard, Farmingdale, NY 11735. Second - Class postage paid at Farmingdale, NY and at additional mailing offices. One -year, twelve issues, subscription rate U.S and possessions $21.95, Canada $28.84 (includes G.S.T. Canadian Goods and Services Tax Registration No 8125166280), all other countries $29.45. Subscription orders payable in U.S. funds only, International Postal Money Order or check drawn on a U.S. bank. U.S. single copy price $3.50. Copyright 1996 by Gernsback Publications. Inc. All rights reserved. Hands -on Electronics and Gizmo trademarks are registered in U.S and Canada by Gernsback Publications. Inc. Popular Electronics trade- mark is registered in U.S. and Canada by Electronics Technology Today, Inc. and is licensed to Gernsback Publications, Inc. Printed in U.S.A.

Postmaster: Please send address changes to Popular Electronics, Subscription Dept., P.O. Box 338, Mount Morris, IL 61054 -99.32

A stamped self -addressed envelope must accompany all submitted manuscripts and /or artwork or photographs if their return is desired should they be rejected. We disclaim any responsibility for the loss or damage of manuscripts and /or artwork or photographs while in our possession or otherwise.

As a service to readers, Popular Electronics publishes available plans or information relating to newsworthy products, techniques, and scientific and technological developments. Because of possible variances in the quality and condition of materials and workmanship used by readers, Popular Electronics dis- claims any responsibility for the safe and proper functioning of reader -built projects based uponor from plans or information published in this magazine.

AmericanRadioHistory.Com O C T O B E R 1 9 9 6 Popular Electronics

P R O D U C T R E V I E W S Larry Steckler, EHF, CET, editor -in -chief and publisher 8 Hands -On Report EDITORIAL DEPARTMENT Dan Karagiannis, managing Sycom Technologies Total Recall digital voice recorder editor Teri Scaduto, assistant editor Evelyn Rose, editorial assistant 26 Product Test Report Joseph J. Carr, K4IPV, APC Back -UPS Pro 650 uninterruptible power supply contributing editor Marc Ellis, contributing editor Jeffrey K. Holtzman, C O L U M N S contributing editor Don Jensen, contributing editor Charles D. Rakes, 12 Multimedia Watch contributing editor Exploring outer space -Marc Spiwak Marc Saxon, contributing editor Marc Spiwak, contributing editor John Yacono, contributing editor 16 Net Watch Halloween on the Web -Dan Karagiannis PRODUCTION DEPARTMENT Ruby M. Yee, production director Kathy Campbell, 59 Antique Radio production assistant Looks like it's mailbag time! -Marc Ellis ART DEPARTMENT Andre Duzant, art director 61 DX Listening Russell C. Truelson, illustrator Slovak radio on the air -Don Jensen CIRCULATION DEPARTMENT Jacqueline P. Cheeseboro, circulation director 63 Scanner Scene Theresa Lombardo, Entering the computer age -Marc Saxon circulation assistant Michele Torrillo, 64 Think Tank POPULAR ELECTRONICS bookstore Jose wins again -John Yacono BUSINESS AND EDITORIAL OFFICES Gernsback Publications, Inc. 500 Bi- County Blvd. 68 Circuit Circus Farmingdale, NY 11735 Op -amp applications - Charles D. Rakes 1 -516- 293 -3000 FAX:1-516- 293 -3115 President: Larry Steckler 72 Computer Bits SUBSCRIPTION Help tools -Jeff Holtzman CUSTOMER SERVICE/ ORDER ENTRY 1- 800 -827 -0383 74 Ham Radio 7:30 AM - 8:30 PM EST Advertising Sales Offices The folded dipole- Joseph J. Carr listed on page 110

Composition by Mates Graphics D E P A R T M E N T S Cover by Loewy Design Cover Illustration by John Edwards 4 Editorial 406 ABC 6 Letters AUDITED

Since some of the equipment and circuit- 28 New Products ry described in POPULAR ELECTRONICS may relate to or be covered by U S. patents. POPULAR ELECTRONICS dis- 76 Electronics Library claims any liability for the infringement of such patents by the making. using, or 81 selling of such equipment or circuitry, Popular Electronics Market Center and suggests that anyone interested in such projects consult a patent attorney. 118 Advertiser's Index 2 118A Free Information Card

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There's a reason haunted houses are popular attractions at amusement parks like Disney's Magic Kingdom. Children, as well as adults, like to have a little spooky fun every once in a while, and October 31st is the perfect time for it. A This month, Popular Electronics brings you a special By Studying at Home Halloween treat: the Goblin Greeter. It's a neat circuit that will Grantham College of Engineering, provide your trick -or- treating visitors with a hauntingly fun now in our -l6iIi year, is highly experi- show when they ring your doorbell. Imagine their delight when enced in "distance education"- teaching by correspondence- through printed a transparent spook, not unlike one they would see at Disney, materials, computer materials, fax, appears in the doorway, wishes them a "Happy Halloween," modem, and phone. and lets them know candy is on the way. The story begins on No commuting to class. Study at your own pace, while continuing on your page 31. present job. Learn from easy -to- understand but complete and thorough lesson materials, with additional help Also in keeping with the All Hallow's theme, this month's Net from our instructors. Watch focuses on a couple of great Halloween Web sites that Grantham offers three separate distance - you can visit today. Look for it this month on page 16. education programs, leading to the following accredited degrees; (1) The B.S.E.T. with Major Emphasis in Of course, we haven't limited this issue to the spirit of spook- Electronics. (2) The B.S.E.T. with Major Emphasis in iness that fills the month. Those who like to save money on Computers. their workbench equipment will love the Delayed Sweep (3) The B.S.C.S. the Bachelor of Sci- - Adapter, which will make an oscilloscope perform like one ence in Computer Science. An important part of being pre- worth hundreds more. That story begins on page 56, and is pared to move up is holding the right only one of the other electronic goodies we have in this issue. college degree, and the absolutely necessary part is knowing your field. Grantham can help you both ways -to Enjoy! learn more and to earn your degree in the process. Write or phone for our free catalog. Toll free, 1- 800 -955 -2527, or see mailing address below.

Accredited by the Accrediting Commission of the Dan Karagiannis Distance Education and Training Council Managing Editor GRANTHAM College of Engineering Grantham College Road 4 Slidell, LA 70460

AmericanRadioHistory.Com TECHNOLOGY UPDATE

Wireless home video broadcasting breakthrough!

Use 2.4 GHz technology to transmit cable, DSS and VCR signals to any other TV in your home... up to 300 feet away!

WAVECOM Jr., from RF -Link, uses 2.4 GHz technology, circularly polarized transmission, four channels and FM to broadcast stereo audio and video signals with clarity never before available.

If you are like most peo- wavelengths ple, you probably own get smaller. more than one television So where 900 Programming from main TV and subscribe to cable or MHz waves satellite programming. have difficulty But in order to extend passing through that special programming certain surfaces (like chicken wire), waves in Exclusive features. One of WAVECOM's to your other TVs, you the 2.4 GHz frequency range can do so easily. key features is the use of four channels for You can use WAVE- have to run miles of wire In fact, the combination of small wavelength interference -free channel selection, which COM Jr. with your: and /or pay for the addi- size and circular polarization transmission makes it arguably the most superior home Cable TV tional connection. Isn't means that there is virtually no obstacle that video broadcasting system available. In many Camcorder there a better way? WAVECOM Jr. cannot overcome. uses, up to four channels can operate simulta- Computer Watch TV on more It's FM, not AM. WAVECOM Jr. uses FM to neously. This feature can be very useful for It also Digital video disk than one set. New transmit signals, not AM, for the same reasons private and civil surveillance systems. facilitates using your existing camcorder to Laser disc player wireless home video that FM stations are superior to AM stations. monitor babies, children and the elderly with- Network TV broadcasting technology High -gain directional transmitting and receiv- in your home or yard. Powered speakers found in WAVECOM Jr. ing antennas are used, instead of omni anten- RF can trans- nas, to minimize interference from unwanted Last but not least, WAVECOM Jr. provides Satellite (DSS) from -Link of rnultipath stereo sound with independent left and right Security camera mit signals from cable, signals and inherent problems digital satellite system (a phenomenon where transmitted signals audio channels. This enables you to hook up VCR movies (DSS), even a VCR, from a bounce around and create "ghosting "). wireless powered speakers to your CD or cas- 1/ Wireless cable video source (your main sette player. All total, WAVECOM Jr. from RF- Link is the solution to the dilemma posed TV) to other TVs in your home, office or school THE WAVECOM ADVANTAGE without sacrificing picture or sound quality. by modern TV programming options. You can You can even use it to transmit between your TV 2.4 GHz transmission. 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High -gain directional antennas. Tf e ered by a 90 -day manufacturer's warranty. quency, enabling it to deliver consistently antennas on both the transmitter anc WAVECOM Jr. System $199 $16 S &H sharp stereo audio and video signals, through receivers are directional -turn them o the System includes one transmitter and one receiver. walls and ceilings, up to 300 feet away. left or right, aim them upwards or down- Additional receivers $129 $12 S &H wards to a seamless link. 2.4 GHz circular-polarization technology. create Please mention promotional code 1761 -PL -6670. For years, the most advanced wireless prod- Circular polar- ucts have boasted the use of the 900 MHz fre- ization. V /AVECOM For fastest service, call toll -free 24 hours a day quency using linear transmissions. But linear Jr. utilizes circular waves can be blocked by studs or other hid- polarizec waves. 800-992-2966 den barriers within your walls. 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AmericanRadioHistory.Com LETTERS An LM386 Question

USING THE LM386 R5 100K I just read "Build the Guitar Track AUDIO s1 Jammer," by Andrew Singmin in the VOLUME LEDI POWER J3 July 1996 issue of Popular Electron- R6 AUDIO 100K R7 ics. Having recently built three differ- INPUT 81 9V ent circuits using the LM386, I have a

couple of suggestions about it. C5 The circuit (see Fig. 1) might have .1 instability problems, depending on the Ca circuit layout and on varying character- Cl 4 100 .1 istics of different LM386s. Using C8 in C3 1, R i-.1 the circuit places the LM386 in its high - J1 27K 10K C8 gain mode (with a voltage gain of GUITAR J2 INPUT about 200 volts). When C8 is used, a v R1 HEADPHONE 100K C2 10T OUTPUT 100 -1.1F bypass capacitor should be R4 o GUITAR 1000pF connected from pin 7 to ground, with VOLUME 1052 o its positive terminal to pin 7. I also try to place C7 as close as possible to the Fig. 1. The Guitar Track Jammer circuit. LM386. That is a good practice with

any high -gain IC (as is mentioned by Linear Devices Databook, pages 1 -29), those circuits had actually been board Joseph J. Carr on page 52 of the July the optional bypass capacitor was only tested. 1996 issue). required for the higher- powered N -4 Typically, on my board layouts, B.S., CET variant (1000 -mW nominal). As I never using the Singmin PCB, the actual Hillsboro, MO had a need to use the LM386 N -4, pre- positioning of the VCC bypass capaci- ferring instead to use the LM380 (2.5- tor (radial type) is no more than one - watt nominal) for higher -power inch linear distance from pin 6, the Thank you for your letter-which I applications, the extra bypass capacitor VCC terminal. I have also tried locating actually received before the July issue was never seen to be needed. the bypass capacitor as close to pin 6 hit the newsstands over here in Out of curiosity, I added the extra as possible, but have found in reality Canada! bypass capacitor to the LM386 N -1 that there is no difference between the During a professional career in and N -3 designs and found no differ- two options. For design access, I have electronics spanning the better part of ence. So, rather than have an extra thus always "spread out" the layout, 20 years, I have built well over 100 cir- component that performed no real where test probing to the IC pins is cuits using the LM386 audio power IC. function, I have always left it out. My required. In every case, by the way, I used "real" circuit board designs with the LM386 In the current layout (some one -inch National Semiconductor devices - have always used 8 -pin IC sockets laid distance), the stability is excellent. never a generic brand- procured out on perforated board and, more Overall space is dictated by the assem- through industrial electronics supply recently, on my custom -designed uni- bly platform size (in this case 2x2 houses. versal PCB ( "Singmin PCB'). In both inches), so there is no need to cram all I had noticed over many years of cases, the circuits have always been the components into one small area. reading articles in Popular Electron- rock stable. Supply voltages generally For hobby projects, ultimate size ics that LM386 circuits sometimes fea- run at 9 volts. shrinkage is rarely an issue with sim- ture the additional electrolytic capacitor The VCC electrolytic bypass capac- ple, one -IC circuits using through -hole tied to pin 7. Inclusion of that extra itor taken to pin 6, however, is a differ- technology, as final package size is lim- capacitor never made any difference to ent matter. Severe instability occurs ited by the relatively huge mechanical my own circuits. The variants of the without that component. Yet, to my components such as the battery, LM386 that I used were the LM386 N -1 surprise, I have seen many published switches, potentiometers, etc. (325 -mW nominal) and the LM386 N -3 circuits in which that capacitor was The design for the "Guitar Track (700 -mW nominal). According to omitted. As my own circuits critically Jammer" came about as a result of a National Semiconduc -tor's specifica- require that component (it is not an need to pace blues guitar (note -for- 6 tions on the LM386 (Special Purposes option), I wonder sometimes whether note transcriptions) audio tapes (B.B.

AmericanRadioHistory.Com King Blues Master I). The unit provided an ambiance that could not be realized by merely running the instructional tape and a guitar amplifier through their own separate speakers. The combined sound presence is quite remarkable to hear. The high -gain selector capacitor, C8, was included to realize a higher gain in order to mask out (my own) very high ambient noise levels from a nearby furnace/fan. Readers working in a quieter environment could either omit C8 or add a series resistor to reduce the gain if needed. That could work ó " well depending on the type of electric ` w . q uo ,' z+. guitar used -i.e., whether the pick -ups CO . .- 5 ° á.` ó : have high or low signal outputs. I have ' = s ó, F c a _ IO found that Fender Stratocasters Q stock 4.2 k G" h work well even with capacitor C8 left ° T out. [ In fact, several local musicians have 2 Hifiw ..c, x T X N expressed interest in having the com- _ Z. c /_, oo . . . . J ..8 - U N li pleted unit made available to them 4. I.n w . `' + c and the electronics board pre- u ÿ U á v zV /or just f v +ti. 3 t. o o s ' E built. Any readers interested in the n U _r -5 G. , a <= -5 .gb 1 same can write to me at Singmin .5 ti aio-o I Enterprises, 9 Milne Crescent, Kanata, ÑtLI : i - . Ca g á cco Ontario K2K 1H7, Canada or fax 613- 592 -3058 for details. Cla -Dr. Andrew Singmin II= '' 2>G Imo= û Q HAVES & NEEDS 1, á Ñ .O I need a little help identifying a 8 > U piece of equipment that I recently 3 made .4 acquired. The case, of 3/8 -inch -0 c wó aluminum, measures 8.5x3.5X2 inch- CIZ u es. On one end is a socket exactly like o 'c the plug on the computer end of a c ó printer cable (i.e., IBM XT), pins and _ U all. It also has a socket similar to the J _ w threaded type used for cable -TV con- 0:3 V E, Zi nections. 0 C. ~ The box is labeled "Motorola, Inc. C.L. ci Made in USA. Model #51895A. Serial #194DPYN357Y. Tx Power Output - 3W. Pri.pwr. 12vdc, NEG gnd. FCC ID: ABZ89FT5725." Except for capacitors and resistors,

I cannot identify any of the components inside. Any help would be appreciated, even if only an address of the company and branch that could (and would) help. Thanks. MICHAEL E. KELLER 322 South West End Avenue Lancaster, PA 17603 -5043

AmericanRadioHistory.Com Total Recall Voice Recorder

Keep track of your thoughts and appointments with Total Recall, the Digital Recorder and Organizer.

Back in the Stone Age, the first the smallest recorders today can fit in VN911 to 4096 kilobytes for the VN947. form of a reminder was proba- a shirt pocket. Sometimes a recorder Four recording modes allow the bly when a cave dweller is the only effective method of getting VN947 to record 23 minutes of audio placed a pebble on top of a rock down information. At a lecture or pre- at the best possible quality level or much like tying a ribbon around a sentation, it can be very difficult to jot stretch that memory into 47 minutes finger-except that there were no rib- down all the significant points while at the lowest quality level, with two bons. Different pebbles meant dif- keeping up with all that's being said. levels in- between. Recordings are ferent tasks, and many pebbles But tape recorders have limitations. It's easily understood even at the lowest meant there was a lot of work to be often hard to find the beginning or quality level, and the quality can be done. But that method had its down end of a message, or to find a blank set for each message. Messages can sides, and wasn't at all portable. spot in time to record something. And also be easily and individually erased Next came chiseling messages into the worst thing that can happen is to or edited. We looked at model VN911, stone tablets, but that was time con- have a tape self -destruct at the wrong which can record from 6 to 11 minutes suming and hardly portable either. It time. of audio, depending on the quality was very difficult to carry stone tablets chosen. And the truth is, for just simple back and forth from work. The advent Total Recall. The Total Recall digital message taking, even six minutes is of paper and pen was a boon to all, voice recorder and analyzer from pNenty of recording time. Prices start because only lightweight paper Sycom Technologies eliminates all of at $149.95 for the VN911. scrolls had to be lugged around. the hassles of tape recording, retains Total Recall is a 'installer and a little Today, we have endless varieties of all of its good points, and adds fea- slimmer than a cigarette pack. Two gadgets that help us remember. Sure, tures that would be impossible with a AAA batteries power the unit for up to people still write down messages on regular tape recorder. In the past, dig- three months, while an additional paper, but others use tape recorders, ital voice recorders couldn't come lithium button cell maintains clock digital assistants, pagers, hi -tech close to the capacity of magnetic functions when the MA cells are watches, and more. Written mes- tape recorders. But Total Recall breaks dead or removed. Because Total Re- sages are very useful most of the time, the magnetic tape barrier with mod- call contains a digital clock and cal- but it's difficult to write and read mes- els that can record up to 47 minutes of endar, it makes sense that it also has a sages on the go, and nearly impossi- audio without a single moving part. built-in alarm. But what's really neat is ble to do while driving. Four models are available, with in- that you can set both the beeper - Tape recorders have been used for ternal memory capacity ranging type alarm and your own custom 8 years to take down messages, and from 1024 kilobytes for the model voice alarms and reminders. Also, all

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BY MARC SPIWAK TECHNICAL EDITOR Exploring Outer Space WINDOWS MAGAZINE

Recently, I renewed my interest me hungry for more details on the disc details each program, the mis- in the American space race, Apollo program; and wouldn't you sions, the astronauts, the spacecraft,

and the Apollo program in particular. I know it, there's more space informa- and more. You will spend hours dig- actually watched Neil Armstrong take tion on the Internet than you probably ging through this disc. You can get

that first step on the moon, not that I want to know about. Just do a search your own copy of this great reference remember any details-I was about 5 for NASA or Apollo and you're there. source for $49.95, plus $6 shipping years old and my dad woke me to While searching for information on and handling.

watch it. The recent movie "Apollo 13" Apollo 13, I stumbled across a compa- In tracking down the Giant Leap

is what renewed my interest. It's a fan- ny called Imagination Software that CD -ROM, I learned of other space -

tastic film, and it's a true story, which was advertising a CD -ROM called related CD -ROM titles and figured I

makes it even more exciting. I think Giant Leap: The Apollo Chronicles. would take a look at them, too. If you

Ron Howard was snubbed for the This was just what I wanted to see, would like to learn more about the

awards-even if Apollo 13 wasn't the and I figured that our readers might entire history of manned space flight, best movie of the year, how could a also be interested. This disc was put and not just about the Apollo missions, talking -pig movie win for best visual together by a very dedicated two -man check out Space: A Visual History of effects? team. The information content is defi- Manned Space Flight from Sumeria. This one contains highlights of the major American programs including Mercury, Gemini, Apollo, and the present-day space shuttles. Over an hour and a half of QuickTime movies from NASA's public- domain footage is included. You'll also find interactive space timelines and textual support for all of the videos and photos. Full search capability lets you find the topics you're interested in. This one sells for $49.95. Two more space -related CD -ROMs are available from Lunar Eclipse Software. This division of LunaCorp. is going to use profits from CD -ROM sales to help pay for the first privately funded lunar mission in history some time in 1999. (LunaCorp is actually run by people who were involved in the NASA space programs.) The goal is to land a pair of unmanned rovers on the moon some time in 1999. Much of what we learned from the original moon missions can be found on the Welcome to the Planets contains this beautiftd image of Jupiter's Loki volcano erupting in a burst Return to the Moon CD -ROM, which of blue and white light. (Cota'tes.y of the National Space Science Data Center). sells for around $29.95. This disc lets you rediscover the past missions by The Apollo program was the United nitely there, and the quality is very viewing over 500 photos, videos, and

States at its best, and I doubt that we good -and content is always more audio clips. It features a lunar atlas could get there again today -there important than presentation glitter. and a vast data bank of lunar informa- would just be too many people Giant Leap is chock full of information. A Video Show Assistant lets you involved with too much to say about tion on the Apollo program, and pro- put together your own lunar multime- everything. We'd never get it off the vides background information on the dia shows with the material included 12 ground. Anyway, seeing the movie got programs before and after Apollo. The on the disc. You can also try your own

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AmericanRadioHistory.Com recorder lets you capture your own explorations, and you can print out sky charts to help you in your own stargaz- ing. This jam -packed title sells for around $59.95. If you are not sure if you are interested in RedShift 2, but would like to view some of its spectacular images and videos, then you should check out Discover Astronomy, also from Maris. This one lets you take in many of the sights and sounds from RedShift, but without some of the fancier features and at a much lower price of only $14.95. Supposedly, much of Discover Astronomy's content was actually generated using RedShift 2. This is a good, inexpensive way to wet your appetite for astronomy. The Dame Was Loaded is a humorous homage to the 1940's detective movies. You play the role of Scott Anger, wise- cracking private eye. NEW STUFF If spy stuff thrills you and you'd like hand at a lunar landing with the Jupiter, Saturn, Uranus, Neptune, to play the role of a CIA operative try- Moonflight simulator. Pluto; and a collection of small bodies ing to protect the cold war peace, then The lunar missions also taught us a including comets, asteroids, and mete- check out Activision's new live- action lot about planet Earth. It all depends orites. Clicking on any one of these CD -ROM thriller Spycraft: The Great on how you look at it, and you really do photos brings up a collection of images Game. In this game you must unravel get a completely different view of Earth of each object. You can zoom into the an assassination plot that could from space. So, plenty of earthly infor- images, listen to commentary, read the destroy world peace. First you are sent mation is contained on the Mission: definition of underlined words, and so to a CIA training facility to learn how to Planet Earth CD -ROM. This disc lets on. Of the many spectacular images manipulate satellite photos, intercept

you examine photographic images of contained on this disc, I particularly like radio communications, trace bullet tra- earth taken from space during the the image of Jupiter's Loki volcano jectories, and electronically sketch lunar missions. Planet Earth also fea- erupting. suspects. These skills and more are tures the first licensed use of the RedShift 2 from Maris Multimedia is necessary to solve the puzzles that will GeoSphere image. This is a single oriented more around astronomy than block your path. Spycraft has an esti- cloud -free view of Earth put together space flight. It lets you explore the mated retail price of $49.95. from hundreds of individual satellite entire universe from your PC -think of Philips Media is offering another images (you've probably already seen it as a desktop planetarium, but better. live- action spy game, The Dame Was it, although not on your computer). You can view the night sky from any- Loaded. This humorous homage to the These breathtaking images are yours where in the world, and at any time in 1940's detective movies lets the player for only $29.95. history (the sky changes over time). assume the role of wise -cracking pri- The National Space Science Data The program is mathematically based, vate eye Scott Anger. From classy Center (NSSDC) houses the greatest so it can quickly calculate celestial joints to sleazy dives, the name of the collection of space -related data in the positions; and images are then gener- game is to solve the case and stay world. These documents, photos, ated by the program. This disc also alive. Thirty characters and a twisting, tapes, and -you guessed it -CD- allows users to download updates to random story line bring the game to ROMs are available to the public. the program -the appearance of a life. A cool jazz sound track and over NSSDC has an entire catalog of CD- new comet, for example. 40 hours of game play is featured on ROMs, all of them packed with data, The disc is loaded with real images this 2 -disc set. You can bring the '40s documents, images, and more. You and video clips of the most spectacular alive and hone your detecting skills for have to be an astrophysicist to be inter- sights in the heavens. You'll find guid- only $39.99. ested in a lot of the stuff. ed tours of the cosmos, interactive Golfing enthusiasts might want to

I checked out a CD -ROM entitled tutorials, maps of the planets, 2D and check out Aces, Eagles, & Birdies from Welcome to the Planets. This collection 3D animations (how does an eclipse Memorex Software. This Gold Edition of images of the planets within our solar occur ?), and more. There are over set contains three CD titles in one system is available for only $10.00. The 2000 links throughout the disc to package for $29.99. The set includes disc first presents a grid of planet pho- Penguin's Dictionary of Astronomy, Picture Perfect Golf; ESPN Golf: 14 tos: Mercury, Venus, Earth, Mars, also included on the disc. A movie Lower Your Score With Tom Kite-

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Halloween on the Web BY DAN KARAGIANNIS

Well, the ghoulish month has the beginnings of Samhain (which the Horror Movie Poster Archive, Horror rolled around again, and with it pagan feast Halloween is based on). Reference, Atlas, Timeline, Interviews comes my review of some macabre On October 31st, it was believed that from the Cabinet, Tales from the sites that are sure to get you in the the "veil between the worlds" was lift- Internet, Horror Audio Archive, Horror spirit of October 31st. Whether you just ed, and that those from the other side Graphics Archive, Horror in the Movies, want some information on appropriate could come through. People feared Horror in Literature, Newsgroups, Links scary movies to rent for a quiet such a thing, as you might expect, and Around the Web, and Halloween Sites Halloween at home, or would like to for that reason, elements of horror on the Web. Each deserves at least a order a costume for a fright -filled party, were always associated with the holi- brief description here. your Net connection can open up a day. The Horror Movie Poster Archive is whole new world of festive opportuni- In modern times, most of us associ- a large archive of graphics files of (you guessed it) movie posters. What's Netscape - [The Cabinet of Casey - Dr. The Horror Web Pagel great about the images here is that file Edit View Go Bookmarks Qptions Qirectory Window Help they usually are a good size to use as 10 Location: hnp //www.car Mx edu/'caseyh/horrn,/mdex hlml Windows wallpaper (that's convenient because reducing and enlarging images decreases their resolution and makes them less attractive). Not all the images are of "horror" movies, howev-

er. Some drama jpegs are here, and I was glad to see a great scan of the Ghostbusters poster as well. Horror Reference is a neat and searchable link that puts a lot of spooky information at your fingertips. The site claims that the lists are not exhaustive, but rather "a rough guide to the myriad individuals and works that fall within the horror genre." If you know a title of some type of horror, but not its creator, for example, this section of the Cabinet should prove helpful. The Atlas is an amazing, graphical - Whether you like horror all year long or just during Halloween time. ghoulish good- based search feature that lets you ies collected at the Cabinet of Dr. Casey. select a part of the world off a map, or by clicking on a country name. Then, ties. So, dim the lights, put on some ate horror with All Hallows Eve you're presented with folklore and hor- eerie music, and point your Web because we like to feel scared on that ror- fiction -based information on the browser to some of these dark day, not because we have some real area. If the information is of the latter domains on the Web. supernatural dread. So, whether you type, the book or movie that is the like horror for one day a year, or if it source is also listed (often with a link THE CABINET OF happens to be your favorite fictional for more information). DR. CASEY escape (it's definitely mine), you'll Now we come to one of the most If you love Halloween, then want to check out The Cabinet of Dr. interesting features of the Cabinet site, chances are you at least like (if not Casey, which carries the appropriate the Timeline. Here you'll find a graphic love) horror. Like the holiday we're cur- subtitle: The Horror Web Page. representation of a timeline that spans rently focusing on, this dark form of When you first access the site, you from the 13th to the 20th century. Just fantasy, which exists because of our will be presented with a classic, black - click the century of interest to learn enjoyment of a good fright, has been and- white, horror -movie image. how horror evolved during those around for quite some time. In fact, the Scrolling down a bit will reveal several years; interestingly, some of the infor- 16 two "H" words have been linked since excellent links, including the following: mation is on the real -life horror that

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AmericanRadioHistory.Com Netscape - [The Horror Atlas] often a long editorial lead time. That's File Edit View go Bookmarks Options Qiredory Window Help the reason I'm writing this column

.21 localion:ihttp /iwNwa. cat pdxedu/`caseyhJharohnap.fvrdexhtml towards the end of May 1996 and it's [What's New? What's Cool? Narrdbook Net Search] Net Directory Sottwate getting published in the middle of August 1996. However, this "August" issue bears the October cover date. Atlas: That means most of you are now reading about Halloween sites I Ck on a;: cator, r use the 1nde:es below approximately a month or month -and- a -half too early. While that could make it hard to get into the spirit of things, it does have its benefits. An important one of those is that if you order something for Halloween, you can definitely have it before the grim eve. And just what would you order? Well, Halloween Mart might be able to answer that question for you. They a have quite a selection of goodies that _EL.1 Document Done you could sure use if you are going to The Atlas located within the Cabinet of Or Casey lets yon click on an urea of the world to learn attend or host a costume party, or just what dark fiction and folklore conies from there. need to suit up the kids for their evening of trick or treating. Let's take a occured, rather than fiction that was 100 best books, and more online hor- look at the links those ghoulish items created (i.e. the Salem Witch Trials are ror fiction. are organized within: a good example of that). Within each Finally, like any good Web site, Clicking on Adult Costumes pro- century heading you can choose from there are links to other great places. vides you with an extensive list of cos- decades of the time period, making it You can go to horror -related news- tumes, and images of a few of them. possible to really pinpoint an era you'd groups, visit links around the Web that You'll find complete outfits of the heroes like to know about. are of interest to horror fans, and even and villains from the Batman movies, The Interviews from the Cabinet check out sites pertaining to Halloween monsters of horror fame, and much link provides you with html- formatted in particular. more. There's something for just about text interviews with famous horror any price range and interest here. authors. There are also images asso- HALLOWEEN MART The Children's Costumes link will ciated with each. In magazine publishing there's help you find just the right outfits for Tales from the Internet is a collec- Netscape - {Halloween Mart - Costumes, Masks, Props, Body Parts] tion of horror fiction written by various file Edit yiew Do Qookmarks Qpdons Directory Window help Netizens. Although the work seems to be from unpublished authors, who 41 NetsiteT (http accessrrv.comihsloweerJ 0 knows? The next big talent could be hiding here. The next two links are similar in RALLOWEEN structure. The Horror Audio Archive and Horror Graphics Archive contain MART numerous files in .au and .jpg formats, 11í1 i N 1 LR2 'S PREMIER HALLOWEEN COSTUME SITE respectively. Horror in the Movies is definitely the link to check out if you plan on watching some scary movies this year on Halloween. You're sure to find just the right macabre film here to suit your taste. Hopefully you have a well - stocked video store nearby. The Horror in Literature link is for those who also enjoy, or perhaps prefer, the theater of the mind's eye. You'll find excerpts from recent horror nov- Plan on celebrating Halloween in a visual atte' the Halloween Mart can fulfill all your costuming 20 els, authors' bibliographies, horror's needs.

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AmericanRadioHistory.Com Netscapc (Halloween Mart Costumes, Masks, Props, Body Parts( Education? file Edit Yiew Do (3ookmarks Qprions Directory Window Help I !í Retirement? Beck Hon. RtbW F#M ANetsite: (http /Ywww accesxnv com/hatoween/adult htm Peace of Mind? What's New? What's Cod? Handbook Net Search Net Directory Software

You have your reasons.

Browse through our list of Adult Costumes. When you decide to order, click on the "Order Forni" image at the bottom of the page.

"The adult cusnanes )(mud at the Halloween Mart are quite impressive looking. Barman )ctn.c should especially get a kick out of this year's featured selections.

your little ones to wear while searching When you are ready to order, just click for If you the Form. No matter what you're saving candy. think some of adult on Order Online ordering could- costumes are reasonably priced, you'll n't be simpler; you get three options: money for, U.S. Savings definitely be pleased with how much There's a conventional order form,

(or should I say, how little) the chil- which would require you to send in Bonds make sense. They're dren's versions cost. your payment; a Netscape- secure backed by the full faith and Now, I'm sure there are more than a credit -card order form, which lets you few Star Trek fans who read this mag- send your card number and order right credit of the United States. azine. To make shopping easy for indi- HOT SITES They earn interest for up to viduals such as yourselves, and to accommodate the large variety of mer- The Cabinet of Dr. Casey 30 years. And their value is chandise available, the Halloween http://www.cat.pdx.edui-caseyh/ horror/index.html Mart made a separate section at its guaranteed to grow at market - Web site called, appropriately enough, Halloween Mart based rates. Star Trek Costumes. These costumes httpl/www.accessny.com/halloween look very authentic, and shouldn't Ask your employer or banker beam too much cash out of your wallet, over the Net; and most innovative of either. all, a Netscape- secure check order

about saving with If you want a simple and extremely form. I haven't seen the latter any- affordable way to dress up, check out where else on the Net yet, but of U.S','Savings Bonds. the Masks link. Several full -head, high - course, I haven't been everywhere on quality masks are available here. the Net either. Apparently, ordering Or for a recorded message Horror- favorite Pinhead is found here, over the Internet is becoming danger- as well as a President Clinton mask ously convenient. Make sure all your of rate information, current with a moving mouth. pointing and clicking doesn't leave you call 1- 800 -4US -BOND Looking to accent a costume you hopelessly in debt!

bought or are putting together your- Well, that's all for this month. I hope 1 -800- 487 -2663 self? Then you should click on either your Halloween is filled with lots of Props or Body Parts. And, if you are thrills and chills, both online and off. working from scratch, you'll also want Until next month, while you're online, to consider getting one of the useful you can reach me via e-mail at peedi- tomes in the Books section. They con- [email protected]. If you prefer snail -mail, Take Jl1Y Ll1 VS Stock ` tain techniques used in Hollywood by send it to me at Net Watch, Popular SnAmerica 0.BONDS makeup and special- effects experts. Electronics, 500 Bi- County Blvd.,

22 A public service of this magazine And here comes the best part. Farmingdale, NY 11735.

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AmericanRadioHistory.Com PROdUCT TEST REPORT

APC BACK -UPS PRO 650 BY STEPHEN A. BOOTH UN INTERRUPTIBLE POWER SUPPLY

Much is made of the importance ies. When it does switch to auxiliary PowerChute Pro software it worked a of connecting computers and power, it can run a substantial multi- bit too well (see Table 2)-a condition audio /video gear to surge- suppression media PC for 5 to 20 minutes, depend- APC says it will have remedied by the devices. Lightning may strike, but it's ing on the load. time you read this. more likely that any power spikes or Additionally, APC's PowerChute APEL evaluated the BackUPS Pro surges reaching your equipment will Pro software for the BackUPS Pro 650 on its own merits, and in conjunc- come as a result of quirks in the elec- series enables users to program a PC tion with the supplied PowerChute Pro trical utility system. Those jolts might for unattended, safe shutdown and software. This program, formerly an not cause instant damage, but take rebooting, among other automated optional purchase, need not be used their toll cumulatively. tasks such as performance -logging. but is bundled with the UPS. Because of their sensational, if- The software gives the BackUPS Pro As an uninterruptible power supply, lightning- strikes nature, over -voltage series plug- and -play compatibility with the BackUPS Pro 650 performed as situations get most of the ink. But Microsoft's Windows 95 operating sys- advertised. Its user -replaceable, hot - under -voltage conditions -brown -outs tem -and also operates with PCs run- swappable batteries delivered 5.5 min- and black- outs -probably cause more ning Microsoft's Windows 3.1 and utes of power under full -load (410 trouble with computers. An abrupt Windows NT, or IBM's OS /2. watts) and 20 minutes at half- load,(205 power failure will cause you to lose any watts). The system's Automatic Voltage work -in- progress you haven't saved to TEST RESULTS Regulation both trimmed overloads as the PC's memory, and may damage The BackUPS Pro 650 was tested great as 12 percent and boosted under - hard -disk drives or other components. at the Advanced Product Evaluation voltage supplies by the same amount, Brown -outs, meanwhile, are treacher- Laboratory (APEL), an independent to keep a computer coasting comfort- ous. They stress electronics compo- testing facility located in Bethel, ably. In the under -voltage situation, with nents, inducing erratic performance in Connecticut. The unit performed quite line -power as low as 103 -VAC, the the short-term and reducing longevity well, in some cases exceeding the UPS would run the PC indefinitely with- overall. manufacturer's specs (see Table 1). out resorting to batteries. The unit's To protect your work and your PC, Meanwhile, in conjunction with the various diagnostic functions worked the machine should be connected to an uninterruptible power supply (UPS), preferably one with a line- conditioner. The UPS part is literally a battery backup that kicks in immediately to run the PC upon a power failure. How long they back up for depends on the model, but at least long enough for you to save your work and shut off the PC properly. The UPS monitors AC line voltage to E determine when to switch to DC. Those á with line- conditioners supplement the w AC voltage during brown -out periods, thus sparing the PC unwanted stress. o They'll act as a surge- suppressors too, buffering any over -voltage. For this test we selected the Back- a, UPS Pro Model 650 ($419) from ó American Power Convèrsion (APC), Ó because the company's Automatic Voltage Regulation system maintains correct power levels within a given The new American Power Conversion Back -UPS Pm Model 650 can possibly save your PC from 24 range- before resorting to its batter- damage caused by brown -outs.

AmericanRadioHistory.Com TECHNOLOGY UPDATE

Fifteen years of microelectronic research makes conventional antennas a thing of the past! This little box uses your home's electrical wiring to give non -subscribers, cable subscribers and satellite users better TV reception! by David Evans

Technology corner Vntil recently, the only convenient way to guarantee great TV recep- 1. Why don't conventional antennas tion was to have cable installed or work as well as the Spectrum? place an antenna on top of your TV. But who Eandlwidth of TV Signal wants to pay a monthly cable fee just to get 7 2 3 4 5 6 clear reception, or have rabbit -ear antennas When TV sigrals that just don't work on all stations? Some peo- Megahertz are tuned at the Ti ple just aren't interested in subscribing to ca- channel's center fre- ble. Or they may live in an area where they quency, optinun can't get cable and TV -top antennas aren't tuning has bees powerful enough. And what about those peo- achieved. ple who have cable or satellite systems but still s Other anternas can't get certain local stations in clearly? processing circuit. It then processes and sepa- can't offer center fre- Now, thanks to fifteen years of microelec- rates the signal into 12 of the best antenna con- quenrituning like the tronics research, a new device has been devel- figurations. These specially processed signals Spectrym Antenra oped that is so advanced, it actually makes route themselves into 12 separate circuits. The can. They only cff. . conventional antennas a thing of the past. It's Spectrum Antenna includes a 12- position rotary Spectrum system such tuning up tc the called the Spectrum Universal tapping switch, the "Signal Precision tuning edge of the center tr_- Antenna /Tuner. Switch" control, which gathers quency. As a result Advanced technology. Who can use Spectrum? twelve of the best antenna con- Other systems your TV picture Just imagine watching TV and figurations. 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AmericanRadioHistory.Com fine, including the site -wiring fault indi- In most cases, PowerChute Pro firmware in the BackUPS Pro 650 cator (e.g., to detect reversed polarity, worked fine, though APEL found would "sense" adequate voltage, and or a missing safety ground). "bugs" known to APC. For example, signal PowerChute Pro to reboot the When the AC supply dips below the software would occasionally lose PC. Shortly after reboot, and with input 103 volts, the UPS is supposed to communication with UPS when the unchanged at 90 -VAC, the monitoring switch to battery power, and it does. At drop -down menus were stressed by circuitry in the UPS would sense inad- that point, you'd get the requisite warn- repeatedly fast mouse -clicks. That isn't equate power and instruct the software ing beeps and should begin to save normal operating procedure, but it's to reinitiate the five -minute shut -down files, close applications, exit Windows something a novice or nervous PC procedure. and shut down the PC in the orderly user might do. In fact -call it bug num- That pattern repeated itself time fashion demanded by the Microsoft ber two-the fault was discovered only after time, with two test units. Our con- operating system. when a promised feature didn't function cern should be obvious: If the cycling were to go on indefinitely, it seemed TABLE 1 -TEST RESULTS logical that eventually the UPS battery would lack the juice to run the PC for The following test results were furnished by the Advanced Product Evaluation Laboratory, the five minutes programmed for shut- an independent testing facility located in Bethel, CT. The software provided by the man- down- resulting in a hard crash. ufacturer was also evaluated. As it turns out, that would not hap- Brand: American Power Conversion pen. According to APC, the unit's "bat- Model: BackUPS Pro 650 tery depletion protection" would not Price: $419 permit the UPS to start up again once battery voltage dipped below a level TEST APEL DATA MANUFACTURER'S SPEC needed to shut down the PC correctly Maximum Capacity 410 watts 410 watts (in terms of time, about 1 minute and Phase Synchronization In phase In phase 45 seconds). Still, APC concedes the Typical Run -Time (Battery): flaw is real, and began its own tests to Half Load (205W) 20.0 minutes 19 minutes find the cause. Full Load (410W) 5.5 minutes 5 minutes The Voltage Regulation: company informed us that the firmware in the - Boost -Input 103 VAC UPS was signaling "all line Output Voltage +12% (115 VAC) +12% clear" when voltage remained con- Trim -Input 138 VAC stant over a range from 89.3 to 93.3 Output Voltage -12% (121 VAC) -12% VAC. The lab was feeding the box a Battery Output (Full Load): steady 90 volts. According to APC, the (Stepped Sine -Wave) 106 VAC 112 VAC fault was that the firmware's threshold

Recharge Time: 4 hours 1 -5 hours was improperly set at 89.3 volts: The Audible Noise: 38 dB <45 dB unit should not restart until input volt- Audible Alarms: age rises above 93.3 volts. In other On Battery Yes Yes words, the shut -off point and turn -on Low Battery Yes Yes point were virtually the same, so the Overload Yes Yes 650 played yo -yo with PowerChute Pro at 90 VAC. The PowerChute Pro software (a sound -effect whereby the software APC assured us that, as a conse- won't close files -you'd need other beeps every four seconds to indicate quence of APEL's discovery, the firm- applications that automatically save PowerChute Pro is on the job). The ware in its BackUPS Pro units would data. But the APC software will safely software was on the ball, but APC con- be reconfigured immediately to set the shut down the PC's operating sys- cedes the sound -effect wasn't. The turn -on threshold at 93.3 volts. Mean- tem-a great idea for those times "beep" will be dropped from future soft- while, the company does not plan to when you're not around to do the task. ware revisions. recall some 400,000 units already sold. You could, for example, program On the positive side, PowerChute APC's rationale is that prolonged the software to commence shut -down Pro certainly shut down the PC as pro- brown -outs at a constant 90 VAC are within five minutes of battery activation grammed. And it automatically reboot- unlikely. The company states that, usu- and to automatically power -up and ed the PC, when informed by the 650's ally, dips so low are variations of brief reboot the PC when line voltage line- monitoring circuitry that adequate duration -occurring mostly in summer returns to the normal operating range. AC power had been restored. Here's when the compressors in climate -con- It's here that APEL discovered an where APEL discovered a flaw. trol equipment induce motor -loads with interesting "bug" in the system (that When the lab dropped line power to high inrush currents. We were told that discovery was replicated in a second, 90 volts, the software shut down the no existing customers had reported separate test unit by the lab and, sub - PC as programmed. But within sec- problems of the type APEL encoun- 26 sequently, by APC's own engineers). onds of shutdown, the microprocessor tered. Again, the company reiterated

AmericanRadioHistory.Com that the battery- depletion protection in antee against surge damage to pro- the BackUPS Pro, when tected equipment. r used with PowerChute Pro, would not perm t a Considering the fickle nature of utili- You can Build Gadgets! drop -dead situation. ty service, a UPS is a sensible invest- why! So much tor under -voltage prob- ment for anyone who uses a PC. Given Here are 3 reasons

lems. Regarding power surges, APC the corrections to the UPS circuitry that BP345-GETTING states that clamp -down response is APC promises, the BackUPS Pro 650 I-ISTARTED IN PRACTICAL TABLE TEST ELECTRONICS$5.95 2- SOFTWARE If you are looking into launching an exciting The APS BackUPS Pro is bundled with PowerChute Pro software, which consists of hobby activity, this text two software modules. Pwrchute.exe is a monitoring module that communicates to the provides minimum es- UPS via the serial port of an IBM -compatible computer running the Microsoft Windows sentials for the builder and 30 easy -to -build fun (Windows 95; 3.1; or NT) or IBM OS /2 operating system. Winchute.exe is a user interface projects every experi- module that permits the operator to monitor and control the UPS via drop -down menus menter should toy with. Printed -circuit board IBM PC and dialogue boxes on the PC display monitor. APEL used an -compatible 486 designs are included to give your project a pro - running Windows 3.1 to evaluate the following PowerChute Pro menu selections. fessional appearance.

SELECTION RESULTS BP349- Practical Opto- Electronic Self Test: PRACTICAL OPTO- Projects Green on -line LED (flashes); amber on- battery LED (on) Yes ELECTRONIC Power switches to battery (confirmed by scope) Yes PROJECTS $5.95 Green LED on; amber LED off Yes If you shun opto -elec- Power switches back on -line Yes tronic projects for lack of PowerChute software displays self -test status Yes knowledge, this is the book for you. A bit of in- Test UPS Alarm: troductory theory comes Red overload LED (on); red replace- battery LED (on) Yes first and then a number of practical projects UPS beeps Yes which utilize a range of opto devices, from a fil- PowerChute software displays alarm -test status Yes ament bulb to modern infrared sensors and emit- System: ters -all are easy to build. (Daily Shutdown Parameters) Shutdown at user -programmable time Yes Practical Electronic Music Projects BP363- Timely shutdown warning message Yes 1-1 PRACTICAL Re -boot at user -programmable time Yes ELECTRONIC (Shutdown Server Now) MUSIC PROJECTS Shutdown at user- programmable time Yes $5.95 The text contains a good- Logging: ly number of practical Maintains a log of UPS condition Yes music projects most often Erase log and start a new log Yes requested by musicians. Diagnostics: All the projects are relatively low -in -cost to build (Simulate Power Failure) and all use standard, readily -available compo- Green on -line LED (off); amber on- battery LED (on) Yes nents that you can buy. The project categories Power Yes switches to battery (confirmed by scope) are guitar, general music and MIDI. UPS beeps Yes Green LED back (on); amber LED extinguished (off) Yes Power switches back on -line Yes Mail to: PowerChute software displays power status Yes Electronic Technology Today, Inc. Configuration: P.O. Box 240 (UPS Shutdown Parameters) Massapequa Park, NY 11762 -0240 Maximum battery run -time programmable by user Yes" Interval between warning messages programmable by user Yes Shipping Charges in USA & Canada (Communications Parameters) $0.01 to $5.00 $2.00 $30.01 to $40.00 $6.00 Sound Effects No $5.01 10 510.00 $3.00 $40.01 to $50.00 $7.00 $10.01 to $20.00 $4.00 $50.01 and above $8.50 see text $20.01 to $30.00...... $5.00 Sorry, no orders accepted outside of USA and Canada. All payments must be in U.S. funds only. instantaneous when subjected to the warrants your consideration. Number of books ordered. 6000 -volt surge specified by the IEEE - Total price of books $ 587 Category-A test, and that its pro- Shipping (see chart) $ Subtotal . $ tection circuitry can backstop the Sales Tax (NYS only) $ approximately 300 volts that might FOR MORE INFORMATION Total enclosed $ pass through. APEL could not simulate Name American Power Conversion Address so big a jolt, but consider this: APC 132 Fairgrounds Road City State ZIP puts its money where its mouth is with West Kingston, RI 02892 Tel. 800 -800 -4APC LPlease allow 6 -8 weeks for delivery. 27 an impressive $25,000 lifetime guar- J

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DESKTOP VIDEO CAMERA 612 -988 -0055; Fax: 612 -988 -0066; mated street price of $695. For further In response to the quickly growing e -mail: videolabs @flexcam.com. information, contact ViewSonic Corp- video -conferencing market, Video - CIRCLE 70 ON FREE oration, 20480 Business Parkway, INFORMATION CARD Labs' FlexCam, an integrated color Walnut, CA 91789; Tel. 909 -869 -7976 camera and microphone designed for or 800 -888 -8583; Fax: 909 -869 -7958. desktop video and communications, MULTIMEDIA MONITOR CIRCLE 71 ON FREE INFORMATION CARD now offers S -video output and an The ViewSonic 17EA multimedia mon- attractively lower price. itor offers the 17 -inch display (16 -inch The 1,3 -inch, high- resolution CCD diagonal viewing area) that is now the HAND -HELD ORGANIZERS S-video camera and the microphone preferred size for today's varied appli- Rolodex Electronics' Hand -Held are mounted on a slender, 18 -inch cations. The flat, square screen deliv- Organizers offer DataGuardTM, which flexible wand that can be easily adjust- ers a full image display to all four uses a Flash ROM memory chip to ed for precise camera positioning. S- corners. Built -in stereo speakers elimi- guarantee against information loss, video provides a sharper image with nate the need to add external ones. regardless of battery life. The three more vivid colors, whether the camera palm -sized models in the line each is focused at its closest range of 1/4 feature an appointment file and a full - inch or at a distance. The added detail view to -do list accessible by date or allows the FlexCam to be used for event, a programmable schedule applications including quality control, keeper and daily alarm, a 200 -year presentations, teaching, and video - monthly calendar, a 10 -digit calculator, conferencing. and password protection for confidential data. Rolodex's PC -Link software can be used to transfer data between any of the organizers and an IBM -compatible PC. Infrared transfer is used to upload or download data to any Rolodex electronic desktop or telephone organizers with at least 32K memory.

The monitor offers resolutions up to 1280x1024 and has an 85 -Hz refresh rate at 1024x768. It also features a low 0.28mm dot pitch with a maximum refresh rate of 120 Hz for a crisp, picture- perfect display. An Invar Shadow Mask increases beam alignment for improved image quality with fewer color and focus shifts. The ViewSonic 17EA has several advanced features, such as OnViewTM an on- screen control system for customizing screen images. The OnView The FlexCam is available in NTSC menu gives the user the option of The Model EL3132, with 32K or PAL formats and includes industry- adjusting up to 20 different settings DataGuard memory, stores up to 500 standard, line -level audio. The camera including brightness, contrast, size, records with 30 lines of information per is compatible with Apple AV Macintosh and positioning. Other features include file, has a six -line/24- character LCD, computers and all popular digitizing ViewMatchTM color control and an anti- and runs on two AAA batteries. The boards for Apple Macintosh and static /anti -glare screen coating. The 64K Model EL3164 can store up to Microsoft Video for Windows. monitor is compatible with PCs and 1000 records and is powered by a lithi- The FlexCam desktop video cam- Macs and provides Plug & Play + um battery. The Model EL31128 stores era costs $395. For more information, (with a CCD -compatible video card) to as many as 2000 records in its 128K contact VideoLabs, 10925 Bren Road support Windows 95. DataGuard memory. All records can be 28 East, Minneapolis, MN 55343; Tel. The ViewSonic 17EA has an esti- accessed by either name or company.

AmericanRadioHistory.Com The EL3132, EL3164, and proprietary Dynamic StabilizerTM shock denotes continuity with a loud beep. EL31128 organizers have suggested absorber and the company's Side The DMM stores measurements in retail prices of $59.99, $79.99.. and Guard stylus protection system. two ways. Its hold button freezes the $99.99, respectively. For more infor- Designed for DJ and broadcast display. The max button compares the mation, contact Rolodex Corporation, use, the SC35C cartridge is built to newest reading with prior readings, and 245 Secaucus Road, Secaucus, NJ work with tone arms requiring a track- then saves only the larger reading. 07096 -2196; Tel. 201 -348 -3939. ing force of four to five grams. Its sty- CIRCLE 72 ON FREE lus assembly is rigid enough to INFORMATION CARD withstand the punishment inflicted by back -cueing (or "scratching "), yet ARM -BAND TOOL KIT compliant enough to provide excellent Paktek's Tool Pak 4RM puts all the mid- and high- frequency reproduction. tools you need close at hand-just above your hand, in fact. Designed to be worn on your forearm, the toolkit features four expandable Velcro straps that allow it to adjust to a wide range of sizes and fit easily over clothing. You can carry your tools with you, yet have The lightweight meter has a very full freedom to use both hands. narrow housing design, accessory jacks on the top, and a display orienta- The rugged and dependable tion that allows one -handed operation. M44GX and M447X cartridges offer It comes in a padded, zippered, mail - value- oriented performance, while the pouch -style case. M7OBX and M92E provide an eco- The LS33 Fieldpack costs $99. For nomic way to upgrade a turntable. more information, contact Fieldpiece Priced at just $24.95, the M92E fea- Instruments, 231 East Imperial tures a biradial diamond tip, a low Highway, Suite 250, Fullerton, CA tracking force range of 0.75 grams to 92635; Tel. 714- 992 -1239; Fax: 714- The 4RM features two large, flap - 1.5 grams, and universal mounting 992 -6541. covered pockets, each with 20 internal capability, fitting both P -mount and CIRCLE 75 ON FREE 1/2- INFORMATION CARD holders to organize small bits and dri- inch standard tone arm systems. vers. Convenient for left- and right - Suggested retail prices range from handed workers, the 4RM can be worn the M92E's $24.95 to $99.95 for the PROFESSIONAL -CLASS on either arm. Its two pockets are model M111E. For more information, DIGITAL MULTIMETERS accessible from both sides. contact Shure Brothers Inc., 222 Wavetek's Models 2005 and 2015 The 4RM toolkit costs $21.97. For Hartrey Avenue, Evanston, IL 60202. autoranging handheld digital multime- additional information, contact Pakiek, CIRCLE 74 ON FREE ters are aimed at engineers, techni- INFORMATION CARD 7307 82nd St. Ct. SW, Tacoma, WA cians, and plant service personnel 98498; Tel. 800 -258 -8458; Fax: 206- responsible for designing, testing, ser- 589 -1091. STICK -STYLE DIGITAL vicing, repairing, maintaining, and CIRCLE 73 ON FREE MULTIMETER measuring electronics or electrical sig- INFORMATION CARD For about the price of an analog meter, nals. The meters' 4000 -count digital field -service technicians can buy a display with 42- segment analog bar PHONO CARTRIDGES stick -style digital multimeter with 300 - graph is the largest in their class, with For audio purists who prefer their amp AC current clamp, complete with 0.78 -inch high numerals. Measuring music on vinyl, as well as listeners a selection of lead and tip accessories, functions include AC and DC volts and who still enjoy their extensive collec- that comes in a carrying case. amps, resistance, diode test, and con- tions of LPs, Shure offers a line of six The meter included in the Model tinuity check with beeper. Both models phono cartridges. Each comes with a LS33 Fieldpack from Fieldpiece mea- also offer frequency and capacitance diamond -tipped stylus and all neces- sures voltage up to 600 volts AC /200 measuring functions, and the Model sary mounting hardware for use with volts DC with a resolution of 0.1 mV 2015 measures AC in true -RMS mode most 1i2 -inch commercial and con- AC or DC, and resistance up to 20 as well. Special features include man- sumer tone arms. Two models can megohms with a resolution of up to 0.1 ual -mode range lock; max/min data also be used on P -mount tone arm ohm. With the AC current clamp hold, which freezes the reading on the systems. attached, currents to 300 amps AC display for later evaluation; and rela- The top -of- the -line M111E features can be measured with a resolution to tive- compare mode. a heat -treated stylus and a biradial dia- 0.1 amp. A built -in frequency counter The compact, lightweight digital mond tip. It is equipped with Shure's measures up to 40 kHz. The meter continued on page 73 29

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AmericanRadioHistory.Com This Halloween greet trick -or- treaters at your front door with a hologram -like ghost and spooky sounds. BY D. DEREK VERNER

Ehach Halloween, legions of little to the deep reverberating tones of an stage magic. Called Pepper's Ghost, witches, devills, goblins, and organ chord, the phantom slowly the technique was made popular in eir ghouV friends arrive at our fades to invisibility. 1863 by Professor Pepper of London doors to receivetheir annual tribute of Does that sound near? If it does, when new manufacturing processes goodies. Now, while giving candy is you'll definitely want to build the made large sheets of plate glass fea- great, the last day of October is also Goblin Greeter described in this arti- sible. about having a little spooky fun. So this cle. It's a startling project that you can Visitors to Disney's Magic IGngdom year, when your costumed visitors whip up in a couple of evenings with can see a modern version of Pepper's show up with their bags and jack parts from your local hardware store Ghost in the Haunted Mansion attrac- o'lantem pails, why not treat them to a and a few simple electronic circuits. tion, where ghostly dancers waltz show that keeps with the "spirt' of the around a ballroom. Our version re- holiday. How it Works. By now you might be places expensive plate glass with in- Imagine this Halloween scenario: A a bit curious as to how the hologram - terior storm- window material avail- few seconds after ringing your door- like ghost image is generated by the able from most hardware stores. Such bell, your visitors hear an unearthly Goblin Greeter. As shown in Fig. 1, the heat- shrinkable plastic film is not only shriek, and a life- sized, full -color, 3 -D optical illusion is created by means of much cheaper than glass, but is also image of a ghost materializes in front an image reflected from a ghost safer to use, easier to store, and lighter of them. The ghost beckons and, in mannequin hidden from direct view than glass. Also, it is so thin that it does sepulchral tones, bids the visors en- of the visitor. That method is actually not produce the double image that ter; then, with a maniacal laugh, and one of the oldest illusions used in occurs with plate glass. 31

AmericanRadioHistory.Com lamp, 11, which shines on a CdS light- dependent resistor, R3. Those components form an optoisolator whose resistance varies with the intensity of the audio signal and, consequently, the

brightness 11. TRANSPARENT of IMAGE OF GHOST One "leg" of a phase -shifting net- REFLECTOR BLACK CLOTH work is formed by R3, potentiometer (SEE TEXT) R1, and capacitor C2. The second leg of the network is formed by R2 and C3. GHOST MANNEQUIN Capacitor C2, charged to a higher voltage than C3, replenishes C3's charge each time diac D1 triggers, thereby reducing the circuit's hysteresis or "backlash." Those components determine at what point in each half of the AC cycle D1 will trigger triac TRI into conduction. The brighter the lamp, the lower the resistance of R3, and the sooner in each half cycle TRI will conduct. When TRI begins to conduct, a 117 - VAC spotlight plugged into AC- socket SOI will be activated. Therefore, the audio signal will control when the spotlight turns on, and the level of the signal will determine the brightness of the spotlight. Inductor L1 and capacitor C1 are used to reduce radio and television interference. Fig. I. As the spotlight in the room gets brighter, the ghost mannequin's reflection will gradually appear in the reflector. With proper lighting, the effect can be quite spooky! PARTS LIST FOR THE GOBLIN GREETER (TO LIGHT CONTROLLER (Fig. 2) I1' PL1 RIGHT SO1 o, SPEAKER- RESISTORS (TO 0 ' LEVEL 117 -VAC J1 RI- 100,000 -ohm linear taper L1' OUTPUT) SPOTLIGHT) AUDIO potentiometer 100µH IN R2- 15,000 -ohm, 1/4-watt, 5% resistor R3- Cadmium- sulfide light - R1 TRI' dependent resistor (see text) 100K 1 PL2 ADDITIONAL PARTS AND MATERIALS TRI -400 -volt, 6- ampere, triac C2 DI C -Diac (All Electronics type ST2 .1 C3 _ or equivalent) 1 'SEE TEXT C1- 0.01 -p,F, ceramic -disc capacitor C2, C3- 0.1 -pF, metal -film capacitor Fig. 2. Here's the schematic for the Goblin Greeter light- controller circuit. As the L1- 100 -1.tH, 2 -ampere choke coil audio input to JI becomes louder, a spotlight plugged into SOI will consequently glow (see text) brighter. II- Miniature lamp, L5 -volt, 25 -mA (see text) w When the mannequin is in darkness, Circuit Description. The Goblin J1 -Phono jack, 1/4-inch m the visitor sees through the sheet of Greeter is made up of Iwo circuits: a PLI -Phono plug, 1/4-inch into the room beyond. Then, as óplastic light controller and a timer. We'll deal PL2-AC plug, 2- terminal eL the lighting on the mannequin is in- with the timer later on; the light -con- SOI -AC socket, 2- terminal rncreased by the circuit, the figure be- troller schematic is shown in Fig. 2. Perforated board, project enclosure, comes more and more visible. The Power for the circuit is provided from a heat sink (for TRI), AC line cord, brightness the lighting is knob, $ of controlled standard 117 -VAC outlet. small pieces of cork (2), ó by one track of a stereo tape record- Speaker -level audio from the right small plastic tube (see text), speaker 117 er, while the second track contains channel of a tape recorder is fed to wire, -VAC spotlight (see text), wire, solder, hardware, appropriate sound effects, such as the circuit through jack J1. That audio etc. 32 cackles or howls. signal powers a small, low- voltage

AmericanRadioHistory.Com The timer circuit shown in Fig. 3 BT PL1 makes the Greeter's operation ce- 9V the ringing of a door- 1I{ o_o pendent upon s1 bell or actuation of a proximity sensor. POWER SO1 It's monostable cir- a straightforward, (TO TAPE cuit, centered around ICI, a 555. RECORDER) Power for the circuit is supplied by a 9- R1 MEG B1; S1 is switch. volt battery, the power PERIOD Capacitor Cl and the setting of po- J1 (TO D1 tentiometer R1 establish the length of TRIGGER') 1N4001 time RY1 will remain closed when a IC1 1 A R 555 7 -9V trigger signal arrives at pin 2 of ICI. is input J1, That signal, which at can be C2 D2 derived from a number of different 1N4001 sources (doorbell, proximity sensor, T°1 'SEE TEXT etc.), as we'll describe later. With the Fig. 3. By setting this timer circuit, }'ou can have the Goblin Greeter Mt sion last for a values shown in Fig. 3, the maximum predetermined amount of time. timing period is about 25 seconds. To change the maximum timing period, insulated mounting system and ther- replace Cl with a capacitor of dif- PARTS LIST FOR THE mal grease. That precaution is par- ferent value (the value of Cl in micro - GOBLIN GREETER ticularly important if the heat sink is farads multiplied by 1.1 equals the TIMER (Fig. 3) mounted on an aluminum project - maximum time interval in seconds). box cover, as it is in the author's heat - ICI timer, integrated circuit Diodes D1 and D2 protect ICI from -555 sink. Otherwise the unit will present a Dl, D2- 1N4001 silicon rectifier inductive spikes when RY1 operates. shock hazard. diode The varistor, MOV1, serves a similar pur- Go on to connect LI to the circuit. If l- megohm linear taper R1- you're using the 100 inductor pose when the unit is connected to a potentiometer -0 available from RadioShack, note that doorbell circuit. R2- 100,000 -ohm, 1/4-watt, 5% Therefore, if When RY1 is closed, power will be resistor it is limited to 2 amperes. supplied to S01. Therefore, if the tape C1- 22-pF, 35 -WVDC, electrolytic you intend to use a spotlight rated recorder used with the Greeter is left capacitor higher than 150 watts or so, substitute in play mode, and is connected to C2- 0.01 -p.F, ceramic -disc capacitor a choke with a greater current -han- S01, the timer will cause the recorder MOV1 -Metal -oxide varistor dling ability. RY1 -volt, 500 -ohm relay to play when the circuit is activated -7-9 In the light controller, the lamp NE1 -Neon lamp, type NE -2 (e.g. when the doorbell is pressed). chosen for 11 depends on the power J1 -Phono jack,'/ -inch The recorder will then shut off at the output of the recorder's amplifier (re- PLI -AC plug, 2- terminal member, the Greeter uses a speaker - end of the relay timing period. Con- SO1 -AC socket, 2- terminal level output, not a line -level one). The sequently, after the audio is shut off, SI -SPST switch the Greeter's light controller also turns B1-9-volt alkaline battery lowest wattage lamp widely avail- off, making your "ghost" and its sound Perforated board, project enclosure, able is the one stocked by Radio - effects vanish. AC line cord, knob, fiberoptic fiber Shack that matches the specifications (optional, see text), wire, solder, in the Parts List. That lamp should be Circuit Construction. Because hardware, etc. suitable for use with even the ear- layout is not critical, the two circuits phone output of a small cassette re- are simple enough to build using ordi- corder; larger stereo systems can nary perforated board. Before you obtained from All Electronics Corp. drive bigger lamps. Almost any small begin, keep the following in mind: (P.O. Box 567, Van Nuys, CA lamp rated from 1.5 to 6 volts will prob- Warning: Because these are cir- 91408 -0567). ably work, but avoid flashlight bulbs cuits that involve AC electricity, Begin assembling the light control- because they generally require more never touch any of the components ler by mounting the potentiometer, re- current than other small lamps. The or connections when the circuits sistor, and capacitors. Then wire the lamp selected need not reach full are piugged.into an outlet. The jacks connections from those components brightness, as long as its intensity var- on the circuits never connect to AC, to the diac and triac. To use the full ies and it produces enough light to be and are safe to touch from the outside current carrying capacity of the triac, seen. of the enclosures. However, if you plan it is essential that it be provided with Take a small piece of tubing cut on using the circuits while they are adequate heat sinking. Keep the fol- from a marking pen. Mount the lamp open or not enclosed, use an isolation lowing in mind, though: in a piece of cork and insert it into one transformer for safety. Warning: Many (not all) TO -220- side of the tube, as shown in Fig. 4. The components needed for the style triacs have the mounting tab Insert light- dependent -resistor R3 into circuits are all available from Radio - common with one of the main termi- the other side of the tube in the same Shack and other suppliers, except for nals. Check with an ohmmeter to see fashion; almost any CdS light- depen- the diac. That type -ST2 diac can be if this is the case, and, if so, use an dent resistor will work in this applica- 33

AmericanRadioHistory.Com CdS MINIATURE outside the circuit. Complete the AC You will need four, 2- inch -long LIGHT - LAMP DEPENDENT part of the circuit by wiring the shared pieces of/cinch copper tubing and RESISTOR connection of SO1 and NE1 to the line four cast -brass street elbows from the cord leading to PLI. plumbing department as well. Brass Finally, insert ICI into its socket. You elbows are better than copper ones are now ready to mount both circuits because their thicker walls hold a in enclosures. thread better, and their outside diam- The author's prototypes were en- eter matches that of the conduit, closed in project boxes with aluminum making a smooth frame over which covers (available from RadioShack). In the plastic will shrink with no distortion. keeping with the Halloween theme, Figure 5 shows how the frame is as- you should consider painting the sembled. Make it as large as possible covers bright orange and decorating so that no portion of it will be visible CORKS them with cutouts from a gift catalog. from the visitor's point of view. If you Fig. 4. To create the simple opto- In the author's timer circuit, the neon have a roll of plastic of the size de- isolator used in the light controller, lamp was mounted behind the front scribed earlier, cut four pieces of EMT mount the light- dependent resistor (R3) cover to illuminate the eyes of a little conduit to 80 inches in length. A tub- and miniature lamp (II) in a small tube. decorative ghost. You can do the ing cutter makes quick work of the job, same by drilling two holes behind the but a hacksaw and file will work as Lion. If you have a few to choose from, eyes and inserting Iwo Ya -inch lengths well. The pieces will make up a square however, pick one that produces the of fiberoptic fibers. Use a soldering frame as tall as a residential doorway widest resistance range. iron to stick the fiber ends to both sides and wide enough so that the edges Connect J1 to the lamp in your of the cover. won't be seen. homemade optoisolator, and then In both circuits, mount the AC sock- The inside of the EMT conduit has a connect the leads of R3 to the circuit. ets on the outside of the enclosures, weld seam that must be filed away You'll need to manufacture a cable to Make sure you never open one of the with a rattail file, so that the short connect J1 to the tape recorder used. cases when the circuits are plugged lengths of copper tubing can be in- The easiest way to do that is to con- into an outlet. serted (as shown in Fig. 5). Using a nect a phono plug, PL1, to some Once you have the circuitry com- propane torch, tin the ends of the speaker wire. If you're using the unit pleted, it's time to start assembling the copper tubing with plumbing solder. with a stereo, leave the other ends larger parts of the Goblin Greeter that Smear a little soldering paste inside stripped so they can be inserted into make the illusion possible. Let's now the end of a conduit and a brass the speaker connector for the right turn our attention to the reflector. elbow; assemble the three pieces; channel. Otherwise, you'll have to and while applying heat with the splice the leads to the right audio Reflector Construction. Although torch, feed more solder into the joints. track. the frame for the reflector can be While the assembly is still hot, wipe off To complete the light- controller cir- made from wood, a much better job excess solder with a clean rag. cuit, connect AC- socket SOI and AC- can be done using electrical metallic Repeat that procedure for one end plug PL2 to the board. Use an AC line tubing (EMT) sold for use as a wiring of each EMT conduit. The other ends cord of the desired length for the lat- conduit. The latter was used in the au- of the conduits will connect to the nar- ter. We'll deal with how to enclose the thor's prototype, and it worked quite row parts of the brass elbows. Assem- circuit after we discuss assembling the well. The EMT conduit comes in ten - ble those pieces on the floor to make timer. foot lengths and is available from sure they form a flat -plane square. To build the timer circuit, begin by most hardware stores at a nominal Then, drill and tap the holes as shown mounting an IC socket on a piece of cost. Four lengths will be required, in Fig. 5. Screw the pieces together perforated board. Then, make con- and the leftover pieces can be used using 8 -32 screws to complete the nections from the pins to the potenti- as described later for the arms of the frame. ometer, capacitors, varistor, jack, ghost figure. switch, and battery. Check the polar- The shrinkable plastic should be of PARTS AND MATERIALS ity of C1, then go on to mount D1 and the type sold for use with picture win- LIST FOR THE REFLECTOR D2, also making sure they are ori- dows or sliding glass patio doors. In ented properly. the author's Greeter, an 84 -inch by 25- Electrical metallic tubing conduit Install the relay next. As shown in Fig. foot roll was used. That's plenty for sev- (four 10-foot lengths) 3, one of the contact connections will eral years of use. (To keep things sim- Shrinkable plastic window insulation, be directly to an AC line cord leading ple, the following assembly details will 84- inch-wide roll to AC -plug PL1. Make the other con- assume you use a roll of an 84 -inch 1 -inch copper tubing (four two -inch nection to R2, AC- socket S01, and width. If you use a roll of a different pieces) Cast -brass street elbow neon -lamp NEI (which is an NE -2 width, adjust the dimensions given ac- (four) Propane torch, plumbing solder, type). When connecting S01, make cordingly.) Also, buy some of the dou- soldering paste, 8 -32 screws, sure you leave a little wire so it can be ble -sided tape normally used to double -sided tape, flat-black paint, mounted on the enclosure; it ob- adhere the plastic to a door or win- and assorted hardware. 34 viously needs to be accessible from dow casement.

AmericanRadioHistory.Com EMT CONDUIT ered by a sheet to give a more phan- appearance. The simplest way to do it tom -like appearance. Now let's look is to use a stereo cassette recorder at what holds the ghost together un- and a 15- second endless -tape car- 1/2 -INCH der that covering. tridge of the kind sold for use in tele- INCHES COPPER 2- Figure 6 is a photo of the ghost's phone answering machines. TUBING frame. To assemble the figure's arms, For the control track you will need a simply use two leftover pieces of con- line -level audio source. That can be duits. For the hands, attach a pair of an FM tuner, which is an excellent rubber skeleton hands that are avail- source of white noise if it is tuned off - able from most party -supply stores station. Connect the output of the SOLDER JOINTS near Halloween time. Mount both tuner to the right line input of the cas- arms to a piece of wood that mea- sette recorder and connect a micro- BRASS STREET sures approximately 18 x 3 x 2 inches. phone to the left microphone input. ELBOW Attach the arm bar to a pho- Set the right level control to minimum tographic light stand, camera tripod, and the left one to the appropriate or any kind of free -standing, tall, thin level for your voice. Then, speaking in object. Then mount a plastic skull (also your ghostliest voice, record your available from party -supply stores greeting while you adjust the right around Halloween) to the top of the channel recording level to make the assembly. If you are not using a light control -track volume increase then stand, you might have to make some decrease (that will make the ghost

8 -32 SCREW kind of "neck" for the skull to rest upon. appear and disappear). To complete the ghost, cover the Around Halloween time many entire figure with a sheet. If you'd like, stores carry tapes containing all sorts you can make a scythe out of card- of eerie sound effects such as howling EMT CONDUIT board, as shown in the photograph at wind, rattling chains, yowling cats, the beginning. and other spooky sounds. If you can Of course, the aforementioned obtain such a recording, play an ap- Fig. 5. On y one end of each EMT propriate section while you are mak- conduit used in the reflector frame is technique for making a phantom soldered. The other ends connect with guest greeter is not the only one you ing the voice track. screws to the brass elbows, making the can use. There are many other pos- Whatever technique or sounds you frame easy to disassemble. sibilities for creating a ghost of your use, make your recording short - own design. You can make use of one seven seconds is about right. After that When the frame is assembled, give of the many over- the -head masks time, turn both level controls to mini- it a coat of flat -black paint and let it available and a dressmaker's dummy, mum and shut off the recorder. That dry thoroughly. That will make it almost for example. Just be sure to avoid dark will allow an eight- second window so invisible in dim light. colors as they will be hard to light with that the timer, set to fifteen seconds, Apply the double -sided tape sufficient intensity. The covering for will not get out of sync with the tape around the outside edges of the your phantom (whether ifs a sheet or (more on the timer in a moment). frame by peeling off the protective other cloth) should only be white or If you prefer a different greeting backing on one side only. Then, re- off -white for best results. each time the bell is rung, use a lon- move the backing facing out on one Another option you might want to ger endless -loop tape and make as edge of the frame. Cut an 84 -inch consider is to have a live person in many variations as will fit on it. Many square of the shrink film and press one costume who can move in an appro- readers of this magazine will have of the factory -cut edges of the film priate and spooky manner. Lacking a more -sophisticated recording equip- onto the tape; secure the film in one suitable volunteer for this time -con- ment and wlI be able to produce corner first. Then, lifting it off the sur- suming activity, try some simple me- tapes in a more professional manner. face slightly, stretch it taut to the other chanical animation instead. For For example, a line -level mixer can be corner, and press it into place. Repeat example, the figure's beckoning hand used to put together a tape consisting with an adjacent factory -cut edge could be manipulated like a mar- of sound effects, music, and narration. after peeling off more backing paper. ionette with a black thread run to a That can be duplicated onto an end- Do that two more times to fasten the motor -driven crank. Similar tech- less cassette as many times as neces- film to the remaining Iwo edges. Fi- niques can be used to operate the sary. A reel -to -reel recorder can also nally, using a hair dryer on its highest skull's jaw or move other portions of be used for playback by splicing an setting, shrink the film following the the phantom. appropriate length of tape end to manufacturer's instructions. end. Making the Recording. Depending If you'd like to make your voice Building the Ghost. The completed upon the recording equipment you sound more haunting, try using some ghost mannequin used by the author have available, there are many dif- reverb, echo, or a voice -changing mi- in his prototype is shown in the photo ferent ways to prepare the all- impor- crophone. You can also try recording at the beginning of this article. In that tant tape that provides the appropri- at one speed and playing back at photo, the body of the figure is cov- ate sounds and controls the ghost's another. 37

AmericanRadioHistory.Com parts: Using shielded audio cable (to prevent false triggering from stray electrical fields), connect the input (J1) of the timer circuit to the doorbell circuit so that when the bell is rung the timer triggers; you might only need to connect the center conductor, If you find that the timer is triggered even when the bell is not rung, try adding a 0.01 -1.1F capacitor between the center conductor and doorbell wiring. You'll know the timer is triggered if NE1 lights (if you added the fiberoptics as described earlier, that will be easy to determine). Using a stop watch, set the timer to exactly 15 seconds. Plug the recorder into a wall outlet, press play and allow the recording to finish and run for an additional four seconds. At that point, switch the plug on the recorder to the socket on the timer. Then plug the spotlight into the receptacle on the Greeter light controller. Adjust the potentiometer on the controller for the widest range of brightness, and set the right-channel volume control on the recorder for the highest level of brightness. The Goblin Greeter is now ready to use under the normal operating conditions we've looked at so far. How- ever, some readers might have to make a few minor modifications to use the Greeter in their homes. One reason why you might have to modify the unit is if you live in a house or apartment without a storm door. You would then have to set up the Goblin Greeter in a window or, for a Halloween party, in an open doorway to a bedroom. Recall that we men- Fig. 6. Here's what the author's prototype ghost mannequin looks like without the tioned earlier how other triggers to sheet that covers it. You can imitate this design using a photographic -light stand, or the circuit, besides a doorbell, could come up with your own phantom assembly. be used. They would be necessary if you wanted to use the Greeter in a room indoors. A passive infrared prox- Setup and Adjustment. Now you're storm door so you can give some imity detector, a photocell, or even a ready to rig all the Greeter compo- soothing treats to the trick -or-treaters mat switch can serve to trigger the nents together and see the rewards of who witness the phantom. unit whenever anyone approaches. your efforts. Refer back to Fig, 1 for an Arrange a spotlight so that only the If you wont the Greeter to work in- overhead view of how the illusion is set figure is illuminated and no light spills doors at a party, the timer portion can up. Begin by opening the front door onto the wall behind it. A black cloth be eliminated, and the unit can be and fastening the reflector frame to hung behind the figure should ac- controlled by a long tape. Try record- the door jamb with duct tape. Set it to complish that quite nicely. If that is not ing randomly spaced messages that an approximate 45- degree angle as done, the wall or any furniture behind serve to announce various party ac- shown. the figure will also be seen in the re- tivities during the evening. Place the mannequin facing the reflector. The room lighting should be So, whether the Goblin Greeter wel- flector, and back far enough so that it either completely dark, or dim and comes trick-or- treaters or serves as a is not visible from the other side of the shielded from spilling onto the man- ghost host for your holiday activities, storm door. Make sure that easy ac- nequin. we're sure you'll find it can enhance 38 cess can be made to unlatch the Now for the electrical setup of the your Halloween experiences.

AmericanRadioHistory.Com lIll)llll1 Ill_IJJL..l!.l

Here's how to enhance USING the look and performance of your next project DIGITAL that requires a readout. PANEL BY BILL STILES

-, o_i.- ummmiionni METERS _,,,,,,,,, ,,

Several suppliers have recently for DPMs that wil work with the circuits 1.999 -volt range will be called 2- volts, started selling digital panel described in this article (note that the a 19.99 -volt range will be called 20- meters for a lot less than older stock numbers for each DPM are volts, etc. DPMs -around ten dollars for 31/2-digit given at the end of each source list- meters and twenty dollars for 41/2-digit ing). Just what kind of DPMs would Power for a DPM. One problem meters. Now that these are available, those be? To avoid any confusion, let's with most or all of the low- priced DPMs what can you do with them? An ap- give the specifications here of what is that the 9- to 12 -volt DC power sup- it plication that might come to mind is we'll be working with. Because many ply must be "floating," which means to build a multi -range DC voltmeter; of the DPMs available from the should be isolated from both input ter- but even using a ten -dollar DPM, the sources are similar, we'll look at one minals of the DPM. Meters with their total parts cost of such a unit would be common one -a 31/2-digit meter negative power supply terminal con- about equal to the cost of one of the available from Marlin PJones and As- nected to the common voltage input lower- priced digital multimeters on sociates (stock number 6929 -ME): terminal are available, but are three the market, and those also measure The unit's character height is one - to five times as expensive (such as AC, resistance, and current. half inch. It has a maximum DC read- Jewell, Martel, and Modutec DPMs). ways for providing So what is a good use for a DPM? out of 199.9 -millivolts DC, with a three There are three to 12 -volt power supply One use is as a voltage or current position, selectable decimal point. an isolated 9- meter for a power supply, battery Polarity is automatic, and the input for DPMs. The simplest power supply is charger, or other equipment, where impedance is less than 100 a nine -volt battery. Because the cur- better accuracy than an analog megohms. The DPM will run on a 9- to rent drain of most DPMs is less than life will be meter is desired. Another is as part of 12- volt -DC isolated source, and has one milliampere, battery using a battery re- equipment that is either not readily an accuracy of one -half percent. long. However, available or expensive, We will discuss Following the usual practice for dig- quires an extra pole on the power re- both ways of using DPMs. ital -meter ranges, we will refer to the switch, and occasional battery 199.9 -millivolt maximum reading as placement. in DPM Specifications. In the "DPM 200 millivolts. When voltage divider re- The simple power source shown DPM is 39 Suppliers" box, you'll find a few sources sistors are used for higher ranges, a Fig. 1 can be used when the

AmericanRadioHistory.Com the minimum DPM supply for accu- be connected in parallel with C1. rate readout) at the lowest possible

(TO input voltage, with a reasonable input Power -Supply Readout. A DPM 120 VAC DPM MODULE) current. (Using a low value for R1 gives makes an excellent output meter for a a high output voltage at a low input power supply, battery charger, or voltage, but a high input current.) Suit- other similar equipment. The circuit

*SEE TEXT able values of R1 and C2 for use with shown in Fig. 1 can be used to power Fig. I. This simple power source can be three transformers are given in Table 1. the DPM, or the one in Fig. 2 if a con- used with a DPM that's connected to an Note that there are different values stant 9 or 12 volts is available. A volt- AC- powered device. depending on the input voltages; age divider (R1 and R2 in Fig. 3) is used both 12 to 14 volts (automotive) and at the input of the DPM to give the connected to an AC- powered de- nine volts (battery) are shown. An in- desired voltage range. Most DPM vice. Transformer T1 should be a 6.3- put current of 15 to 20 mA is assumed. modules have locations on their cir- volt power type; the smallest current The column for "minimum voltage" is cuit board for such voltage- divider re- rating available will be more than ad- the lowest input voltage for eight volts sistors, which may be marked RB and equate. If you can't find a low- current output. (The Jameco transformers RA on the board. If those resistors are 6.3 -volt transformer, use the center were not tested, but their published located off the DPM board, a jumper tap and one end of the secondary of specifications are identical to those of must be installed, if not already pres- a small 12.6 -volt transformer. the Mouser transformers.) ent, at the RB location on the board.

For either AC- powered or battery - The waveform produced by this cir- In the setup in Fig. 3, a ratio of 9 to 1 powered equipment, the DC -to -DC cuit is not symmetrical, and reversing for R1 and R2 will provide a maximum

power supply shown in Fig. 2 can be the secondary leads of T1 changes reading of 2 volts, with 99 to 1 provid- used. (This circuit is modified from Fig. the output voltage. Both connections ing a maximum of 20 volts, and 999 to

6 of "Voltage Converters" by Ray Mar- should be tried, and the one produc- 1 yielding a maximum of 200 volts. ston, which appeared in Electronics ing the higher voltage should be Resistors R1 and R2 should be one - Now, April 1995.) Transformer T1 is a used. Also, for the 42TL016 and percent or closer tolerance. One -per- 600 -ohm to 600 -ohm unit, with one or 42TM016 transformers, slightly higher cent resistors are available from Digi- both windings center -tapped (Hosfelt output voltage is produced if the Key Corporation (PO. Box 677, Thief Electronics number 56 -297, Jameco winding marked "P" is used as the sec- River Falls, MN 56701 -0677; Tel. 800 - Electronics number 125356 or 105902, ondary in this circuit. Transistor Q1 can DIGI -KEY), Mouser Electronics (12 Em- or Mouser Electronics number 42TL016 be a general -purpose NPN unit. Sev- ery Ave., Randolph, NJ 07869 -1362; or 42TM016 should all work). Zener- eral 2N3904, 2N4401, and MPSA06 Tel. 800 -346- MOUSER), or from many diode D2 prevents the output from units were tried, and all worked fine. If local distributors. (Many "industrial going over 12 volts at higher inputvolt- there is not a bypass or filter capacitor electronics" parts distributors stock ages. Because of the high internal Im- at the DC input source, a 47 -1.1F or one -percent resistors, and will sell pedance of the power supply, a series 100 -11F electrolytic capacitor should them and other parts in small quan- resistor is not needed before D2. tities to individuals.) One -half and Values used for R1 and C2 vary, de- one -tenth percent resistors are man- PARTS LIST FOR THE pending on the transformer used and ufactured, but are very expensive and AC POWER SUPPLY (Fig. 1) the input voltage. The best values can difficult to find in small quantities. be determined by building or bread- Because most 3 -1/2 D1- 1N4001 silicon rectifier diode digit DPMs have boarding the circuit, using a capaci- C1-220 -µF, 16 -WVDC, electrolytic a stated accuracy of one -half per- tor substitution box for C2, and a capacitor cent, using one percent resistors will resistor substitution box or a 100,000 - T1 -120- to 6.3 -volts AC power degrade the accuracy slightly. One ohm potentiometer for R1. (The DPM transformer (see text) way to improve the accuracy is to pur- should be connected to the output.) Perforated board, wire, solder, chase five or ten of each value resistor Values are selected for a minimum hardware, etc. needed. Then measure each of the output voltage of eight volts (about resistors, using a digital multimeter, and select the one nearest the center TABLE 1 of the range of measurements. Transformer Input Minimum R1 C2 It is usually necessary to connect Voltage Voltage two resistors in series for use as either R1 or R2 to obtain the exact ratio. For Hosfelt 12 - 14 9 56K 0.01 -µF Electronics example, for a ratio of nine to one with 56 -297 9 7 18K 0.047 -µF an input resistance of about one megohm, R1 can be 909,000 ohms, Mouser 12 - 14 9 27K 0.022 -..F and 82101,000 ohms (100,000 in series Electronics with 1000). For a lower input resistance 42TL016 9 6.5 12K 0.047 -µF of 200,000 ohms, R1 can be 180,000 Mouser 12 - 14 9 33K 0.022 -µF ohms and R2 can be 20,000 ohms, Electronics both stock values. If a DPM is being 42TM016 40 9 6.5 15K 0,047 -µF used to measure high voltages, note

AmericanRadioHistory.Com used for each decimal -point location. It might be easier to find the correct jumper location by experiment. (TO DPM MODULE) If a DPM output meter is being installed on a variable -voltage power supply with a maximum output over (TO 20 volts, it would be necessary to use a DC 200 -volt range. That would give a SOURCE)' least- significant digit of 0.1 volt. If more accuracy is needed at low voltages, "SEE TEXT there are Iwo solutions: First, use a 4'/2- Fig. 2. This DC -to -DC power supply can be used with either AC- or battery- powered digit DPM. Second, use a range DPM modules. switch, which is shown as S1 in Fig. 4. In that circuit, suitable resistor values are ON- MODULE 909,000 ohms for R1, 90,900 for R2, R1' RESISTOR LOCATIONS' and 10,100 (10,000 in series with 100) (RB) RB RA for R3. The second pole of S1 is used to switch the decimal -point location. VIN (Remember, you might need to experiment to find the correct decimal - point jumpers.) DECIMAL - POINT A DPM can also be used as a DC JUMPERS' ammeter (see Fig. 5). The value of shunt -resistor R1 is calculated with Ohm's Law. For a maximum reading of 2 amperes, R1 should a 0.1- ohm,1- COMMON be watt, 1- percent resistor (obtainable +V - 'SEE TEXT (TO from both Digi -Key and Mouser, listed DPM POWER as "silicone- coated wirewound "). For SUPPLY) a 200 -milliampere range, R1 is 1.0 Fig. 3. A voltage divider (shown here as RI and R2) can be used at the input of a ohm (available in the same type). For DPM module to provide the voltage range. Most DPM modules have locations desired a 20- ampere range, R1 is 0.01 ohm; a on their circuit board for such voltage- divider resistors, which may be marked RB and wire shunt is probably the best way of RA on the board. getting that value. Components R2 and Cl bypass any AC or noise across +VIN Rl.

R1' o l Automobile Voltage Monitor. RANGEE Because a DPM's power supply must

20V O O +VIN R2* S1 -b PARTS LIST FOR THE 200V C1' --O GNP DP1 O DC-TO-DC SUPPLY (Fig. 2) DP2 O- R3* -:, +V DP3 O-- SEMICONDUCTORS o -V Q1- 2N3904 or 2N4401 general- DPM purpose NPN transistor MODULE COMMON D1- 1N4001 silicon rectifier diode D2- 1N4742A 12 -volt Zener diode +V -V 'SEE TEXT (TO DPM CAPACITORS POWER SUPPLY) Cl, C3- O.1 -µF, Mylar or ceramic - Fig. 4. If more DPM accuracy is needed at low voltages, use a range switch (shown disc text here as SI). The second pole of the switch sets the decimal -point location. C2 -Mylar or ceramic -disc (see and Table 1) C4-22 -µF, 16 -WVDC, electrolytic that the maximum voltage with R1 on ing from 0.01 µF to 0.1 µF which by- the DPM circuit board is usually 500 passes any AC or noise on the input for ADDITIONAL PARTS AND volts. Also, the maximum voltage rat- more stable readings. MATERIALS R1 -1/4- or 1/2-watt, 5% resistor (see ing (flash voltage) of 1/4 -watt and %2- Most DPM modules have positions text and Table 1) watt resistors is 150 to 250 volts, requir- for three jumpers, grounding one of TI-600- to 600 -ohm, center- tapped ing R1 to be two or three resistors (of three terminals, which allow the user transformer (see text) in to the approximately equal value) series select the display of decimal Perforated board, wire, solder, for measuring 500 volts. Capacitor Cl point. The instruction sheet is often un- hardware, etc. is a ceramic -disc or Mylar unit, rang- clear as to which jumper position is 41

AmericanRadioHistory.Com automobile voltage monitor. Cost of the regulator is warmer. There is also a the parts is about $25. A 99 -to -1 volt- voltage drop in the wires from the bat- age divider is used at the input of the tery to the instrument panel. If a high DPM. Resistors R2 and R3 can be any load is turned on (such as the head- values with a 99 -to -1 ratio. One suit- lights or the heater/AC blower), the able set of values is 1.0 megohm for R2 voltage at the lighter socket will be and 10,100 ohms for R3 (you'll have to reduced slightly. use a 10,000 -ohm resistor in series with By adding a few parts to the porta- a 100 -ohm one; one million divided ble version of the Automobile Voltage (TO tl by 99 is actually 10101, but 10100 is Monitor, it can do double duty as a CURRENT (TO DPM (see Fig. 7). SOURCE) POWER SUPPLY) close enough). multi -range DC voltmeter 'SEE TEXT Capacitors C5 and C6 bypass The cost of the modification parts is Fig. 5. As shown here, a DPM module electrical noise, which can cause un- low enough ($12 to $15) to make this a can be used as a DC ammeter. stable readings. For portable use in practical way of having an extra dig- more than one car, an input cord with ital DC voltmeter. Components R9 and C6 bypass any AC or noise on the PARTS LIST FOR THE a lighter plug on one end and a coax- DC AMMETER (Fig. Si ial DC power plug on the other (such input. as Radio Shack 270 -1533, 270 -1534, or The use of D3 was suggested by R1-1 -watt, 1% resistor (see text) 270 -032) can be used. Jack J1 should Charles Hansen in a "Letters" column R2- 47,000 -ohm,' -watt, 5% be selected to match the DC power of Electronics Now (October, 1995). He resistor plug on the cord. Test leads attached suggested a low- leakage Zener di- CI- 0.1 -pF, ceramic -disc to a plug that matches J1 will allow ode to protect the DPM in case R8 Perforated board, DPM module, testing at any point in the car elec- opens and a high voltage is mea- wire, solder, hardware, etc. trical system. If the monitor is perma- sured. The author has been unable to nently installed, the input can be locate any Zeners specified as low - be isolated from the voltage it's mea- wired directly to a point in the car that leakage. However, many standard suring, it becomes difficult to use it to is switched on by the ignition switch. Zeners have low enough leakage to measure a vehicle's battery; in other If you are monitoring the voltage of be used for D3. Glass -case diodes in words, you'd need a separate power a car's electrical system, what volt- ratings of 10 to 15 volts (1N4740 to source. A 9 -volt battery could be ages are correct? Many references used, of course, but that would require give a range of 13.8 to 14.8 volts, for a PARTS LIST FOR THE a power switch, which isn't very prac- 12 -volt system with the alternator AUTOMOBILE VOLTAGE tical if the DPM is installed as a perma- charging. Manuals for several GM MONITOR (Fig. 6) nent voltage monitor. Another pos- cars, however, give a range of 13.8 to SEMICONDUCTORS sibility is to use a small 12- volt -coil 15.2 (a Chevrolet mechanic with 25 2N3904 general -purpose NPN relay to turn off the DPM battery when years experience told us that up to Q1- transistor the ignition switch is off, but that would 15.5 volts will not cause any problems). DI- 1N4001 silicon rectifier diode still require occasional battery re- Many voltage regulators are temper- D2- 1N4742A 12 -volt Zener diode placement. ature compensated, and the reading The DC -to -DC supply shown in Fig. 6 will be near the high end of the range RESISTORS RI -%- or 1/2-watt, 5% (see text and is a solution to providing power for an at low temperatures, dropping when Table 1) J1 R2- 1- megohm, 1 -watt, Iß6 (see AUTOMOBILE R2' text) VIN 1 MEG R3- 10,100 -ohm, 1/4-watt, 1% (see Q '44 +VIN text) C5 R3' 100 10.1K DPM CAPACITORS O ONO MODULE Cl, C3, C6- 0.1 -p,F, Mylar or o +v ceramic -disc C2 -Mylar or ceramic -disc (see text o v and Table 1) R1' C4- 22 -ILF, 16 -WVDC, electrolytic C5- 100 4LF, 25 -WVDC, electrolytic Ti- D2 r ADDITIONAL PARTS AND N 1N4742A C3 l o D1 MATERIALS T, ó 1 N4001 T1 --600- to 600 -ohm, center -tapped transformer (see text) 1 T22 11-See text T,. C2' Perforated board, enclosure Q1 (RadioShack number 270-222 or (Et? 'SEE TEXT simi ar), DPM module, input cord (see text), wire, solder, hardware, Fig. 6. This DC -to -DC supply solves the problem of providing power for an etc. 42 automobile voltage monitor.

AmericanRadioHistory.Com -0 S2-a

O o 200mV 2V R4" 4 R9 9.09 MEG 20V DVM 100K o +V1N 200V S2-b St-a o O D3" 't R5 500V-0 12V DP1 o 909K C6 DPM DP2 o 1 7` o GND MODULE (TO DP3 o TEST R6 +V LEADS) 90.9K ---0 -V R7 131 9.09K 9V F-

R8" 1.01K o-' o 1 o S1 -c

D1 D2 J1 1N4001 1N4742A AUTOMOBILE + C3 VIN R2' C5 R1 22 1 MEG 7k 100 T C2" in R3" 10.1K Q1 T 2N3904 'SEE TEXT

Fig. 7. By adding a few parts to the portable version of the Automobile Voltage Monitor (shown in Fig. 6), it can do double duty as a multi -range DC voltmeter.

1N4744) seem to be best, although a GC. A two- position rotary switch could (TO VOLTMETER AND few of them have too much leakage. also be used, it is larger +1V -5V ZENER DIODE but and might Several Zeners with black plastic BEING TESTED)" require a larger enclosure. (On some cases all had too much leakage, as DPMs, the common terminal for the well. So what's the best way to select a R1 decimal point jumpers is not con- R2 Cl Zener? 10 MEG nected to the common input termi- 1 The circuit shown in Fig. 8 can be nal, so S1 -c would go to the common used to test Zener diodes for leakage. 'SEE TEXT terminal for the decimal -point jum- The input voltage is one to five volts. Fig. 8. This circuit can be used to test pers instead of to ground.) Potentiometer R1 can be a 5000-ohm Zener diodes for leakage. Use it with a A 2 -pole, 5- position rotary switch is to 50,000 -ohm unit. Capacitor Cl by- digital voltmeter that has an input used for S2. It should have a high in- passes stray AC pickup, but because resistance of 10 megohms or higher. sulation- voltage rating, because in of the very high circuit impedance the higher ranges nearly all the input the parts should be kept close to- ities, as some will show leakage at voltage is across R4 and its terminals gether, and the negative input termi- only one polarity, and both are impor- on S2. Voltcge ratings for the insula- nal connected to a ground to make tant to allow measurement of positive tion of rotary switches are seldom the circuit more stable. and negative voltages. published, except for switches sold by Use the circuit with a digital volt- Refer back to Fig. 7. The polarity of Mouser Electronics. Their stock meter that has an input resistance of D3 is not important; either polarity will number 10WA125 (2 -pole, 6- position 10 megohms or higher. Adjust R1 for a protect the DPM. Switch S1 is a 3PDT with an adjustable stop) is rated as reading of about 250 millivolts. A low - miniature toggle unit (Circuit Spe- having a wcrking voltage of 300VDC, leakage Zener will not change the cialists number 8405 or GC Electronics and a breakdown voltage of 1000V reading when it is connected to or number 35 -036). Also, 4PDT switches RMS. Their lower- priced switches disconnected from the circuit. The di- are available from Hosfelt Electronics, (10YX025 and 10YD025), which are ode should be tested with both polar- All Electronics, Circuit Specialists, and similar in construction and terminal 43

AmericanRadioHistory.Com PARTS LIST FOR THE 20 IC1 DIGITAL DC VOLTMETER 1205c2 S2-a ON LM317T R5' R6' (Fig. 7) o ADJ 12.40 1350 2000 S1 OFF SEMICONDUCTORS Q1- 2N3904 general- purpose NPN R2 transistor 10K TEST Dl- 1N4001 silicon rectifier diode 02 LEADS SAI* 2N3906 D2- 1N4742A 12 -volt Zener diode R3 D3 -Zener diode (optional, see text) 2 2K + R4 RESISTORS 3.3K (All resistors are 1/4-watt, 1% units, B1 S2-b --o unless otherwise noted.) 9V R1 -1- or' -watt, 5% (see text and LED1' Table 1) R2- 1- megohm (see text) R3- 10,100 -ohm (see text) C5 A S2 -c R4- 9.09 -megohm (see text) 100 R7' R5-909,000 -ohm 180K R6-90,900-ohm R7 -9090 -ohm R8-1010 -ohm (1000-ohm in series with 10 -ohm) +VIN DP1 R9- 100,000 -ohm, '/4- or 1 -watt, 5% 03' O DP2 O CAPACITORS DP3 Cl, C3, C6-0.1- aF, Mylar or GND R8 ceramic -disc D1 o+V 20K DPM C2 or ceramic -disc (see text 1N4001 -Mylar O -V MODULE and Table 1) I.71') N C4- 22 -µF, 16 -WVDC, electrolytic 1 N47Dz42A'11 C5- 100 -u.F, 25 -WVDC, electrolytic g C3 C4 ADDITIONAL PARTS AND II 22T MATERIALS Cl T1 -600- to 600 -ohm, center- tapped C2' transformer 1 (see text) 1M 01 .11-See text 2N3904 R1' 'SEE TEXT Sl -3PDT miniature toggle switch (see text) S2 -2P5T rotary switch (see text) Fig. 9. This direct -reading self-contained Low -Ohms Meter uses the four -wire, B1-9-volt alkaline battery constant-current method of resistance measurement. That eliminates any effect of test - Perforated board, enclosure (Radio lead resistance on measurements. Shack number 270 -222 or similar), DPM Module, input cord (see There is no significant change in the tance measurement is used; each text), binding posts (2), test leads, input resistance when switching test lead is a two- conductor wire such battery snap, wire, solder, ranges. For that reason, this meter as zip cord. The two -wire test leads hardware, etc. makes a good readout for the au- eliminate any effect of test -lead resis- thor's Megohm Tester described in "Ex- tance on the measurement. Contact spacing to switches from most other panded Resistance Ranges for your resistance of the test clips must also suppliers, are rated as having a DMM" (Popular Electronics, De- be eliminated; the contact resistance breakdown voltage of 500VAC for 60 cember 1995). of ordinary plated -steel alligator clips seconds. is too high. Also, their resistance, from For sufficient voltage rating, R4 (9.09 Low -Ohms Meter. The author's Low - the solder lug to the end of the clip, is megohms) must be made up of Ohms Tester (also described in the "Ex- about one milliohm. For a 41/2 -digit smaller -value series- connected re- panded Resistance Ranges for your DPM, the test clips should be Kelvin sistors. In the prototype, four 2.2- DMM" article) can be converted to a Clips (such as Mueller 75K, available megohm, 1/2 -watt, 5% units were used, direct -reading self- contained Low - from Hosfelt Electronics as stock in series with a one -megohm multi - Ohms Meter by adding a DPM and number 52 -75K). The jaws of these turn trimmer potentiometer, such as a the power supply of Fig. 2. The result- clips are insulated from each other, Bourns 3006P or Spectrol 43P To cali- ing configuration is shown in Fig. 9. and you can connect one wire of a brate R4, measure a voltage just un- Using a 31/2 -digit DPM will give a test lead to each jaw. Thus the voltage der 200 millivolts, with S2 in the 200 - lowest reading of 1.0 milliohm, while a measured at the jaws of the clip con- mV position. Then set S2 to the 2 -volt 41/2 -digit DPM will provide a reading nected to the meter will not include range, and adjust the trimmer poten- as low as 0.1 milliohm. The four -wire, any voltage drop at the contact resis- 44 tiometer for the same reading. constant -current method of resis- (Continued om page 79)

AmericanRadioHistory.Com Here's a panorami look at those invol hob

Today, with about 650,000 li- stations from their homes, cars, boats, members were Albert Hyman, Bob censed radio amateurs in the airplanes, and the outdoors. In doing Almy, and Peggy Murray. They called United States, amateurs or so, they make friends around town their station "Hyman-Almy- Murray." "hams" are better known than they and around the world. They commu- Sending the name in code was te- were years ago. But the public knows nicate with each other for fun, in com- dious, so they contracted It to Hy -AI- little of what hams are all about- petitive on- the -air contests, and In Mu, or HYALMU, using the first Iwo let- even though many well -known per - real -life emergencies. ters of each of their last names. sonalities are, or were, amateurs (see Having said all that, have you ever In 1909, confusion resulted be- the "Well -Known Radio Amateurs" wondered why radio amateurs are tween their callsign and signals from box). Fewer still know where the slang known informally as "hams," besides the Mexican ship, Myalmo. So they de- term "ham" comes from, are aware of the formal term "radio amateur"? Just cided to use only the first letter of the hobby's traditions and culture, where does the term come from? Are each name, Identifying their station know about some of the neat tech- hams connoisseur pork tasters? Are as HAM. That was fine, because in the nologies in which hams are involved, they folks who live high off the hog, unregulated, pioneering days of the or understand amateur radio's dis- overacting actors and actresses, non- wireless era, amateur -radio operators tinctive, even impenetrable lingo. professional dabblers, hobbyist ec- picked their own call letters and their Let's talk about these things, shall we? centrics, or what? operating wavelengths. The designation of "ham" never has There's more to the story, reportedly Hams? Amateur radio is the practice been satisfactorily explained; history is found in the Congressional Record. of communicating using the elec- murky enough that we can't precisely The resulting interference between tromagnetic spectrum. Radio ama- trace the word's origin. But we can at amateur and commercial stations teurs operate personal two -way radio least give some clue as to its historical generated heated disputes. The sit- equipment from various locations, no- usage in amateur radio by examining uation came to the attention of Con- tably from their homes and auto- four possibilities for the origin of the gress, which considered legislation to mobiles. Hams are properly called term. limit amateur activity. In 1911, Albert radio amateurs, and the technically Possibility one is that the word Hyman (one of station HAM's oper- precise name for their hobby is the "ham" or "HAM" was applied in 1908 ators) chose the controversial Wireless amateur -radio service. as the callsign of one of the first ama- Regulations Bill as a topic of a thesis at Amateurs, who come from all walks teur wireless stations, operated by the Harvard. An instructor insisted that he of life, operate their two -way radio Harvard Radio Club. The operator- send a copy of the thesis to Senator 45

AmericanRadioHistory.Com the American Radio Relay League (ARRL) Public Information Manager. In a 1993 letter to the editor of Popular Electronics, Steve advanced another possible explanation that considers "ham" to be just short for "Hiram," re- ferring to the ARRL's revered founder, Hiram Percy Maxim, who is known as "The Old Man" of amateur radio. Another explanation suggests that perhaps "ham" is just the shorthand "am," as in amateur. But Steve suggests that, in any case, we apply the science and philosophy rule of Oc- cam's Razor, or parsimony. That rule says that you "do not apply multiple entities without necessity" to conun- drums such as these. In other words, always select the simplest of competing explanations for unknown phe- nomena. Many amateurs enjoy handling message traffic. One of the major vehicles for What do you think? While ifs a little supporting members of the military services is the Military Affiliate Radio System convoluted, the author leans toward (MARS), which operates many networks that encompass separate Army, Navy, and Air possibility one, even if it doesn't quite Force organizations. meet the test of Occam's Razor. How- ever, surely there are other convincing David Walsh, a member of the corn - Radio, or HAM for short, and people hypotheses that one might advance. mittee hearing the bill. Walsh was im- who built and used radios thus came But these hints as to the possible origin pressed with Hyman, and he asked to be known colloquially as HAM radio of the word are interesting and fas- him to appear before his committee. operators. Does that sound plausible? cinating to recount. Hyman described how station HAM Possibility three was suggested by was built, and he decried the fact that Bill Johnston, WB5CBC. He wrote in Amateur Radio's International if the bill were passed, the operators November 1976 to QST and noted Basis. Although they're by definition would have to close down because that in the 1800s, "ham" was slang hobbyists, radio amateurs aren't inter- they couldn't afford the license fees or used by railroad telegraphers to de- lopers in the radio spectrum. Embod- meet other requirements of the bill. In scribe inexperienced telegraph op- ied in international agreements and the debate, station HAM became a erators. The definition of a ham as a the radio rules and regulations of our rallying symbol of amateurs who poor operator probably first ap- own government are definitions of hoped to be saved from the "men- peared in print in G. M. Dodge's clas- the amateur -radio service as a fully ace" of the big commercial stations sic book, The Telegraph Instructor, in authorized user of designated that didn't want meddlesome ama- 1898. The uncomplimentary term car- portions of the electromagnetic teurs messing with the increasingly ried over to the spark era, when radio spectrum. valuable spectrum. When the bill amateurs competed chaotically with According to the radio regulations reached the floor of Congress, each a variety of commercial stations for of the International Telecommunica- speaker talked about "poor little am- given wavelengths. tion Union (ITU), a United Nations ateur station, HAM." National publicity Especially before Congress and the agency headquartered in clearly identified station HAM with ra- IDept, of Commerce (which regulated Switzerland, amateur radio is a bona dio amateurs. Could that be the ex- early radio law under the Radio Act of fide "radiocommunication service." planation? 1912) relegated hams to below 200 Its purpose is self -training, intercom- Well, possibility two is also interest- meters (1500 kHz) -wavelengths that munication, and technical investiga- ing. Dennis Burgoyne, KE8EY, in a De- then were considered practically tion by persons interested in radio cember 1990 letter to the editor of worthless- amateurs were notorious technique solely with a personal aim CompuServe Magazine, suggested for interfering with commercial signals and without any pecuniary (mone- an acronym -based origin. It seems and bringing on complaints about tary) interest. that a popular, early 1900's magazine, jamming. Radio amateurs, who per- Internationally, various frequency Home Amateur Mechanic, featured haps were unfamiliar with the uncom- bands are allocated to the amateur - articles on do- it-yourself projects. In plimentary meaning of the term radio service; unlike broadcasting sta- one issue, an article described the ra- "ham," happily picked it up and ap- tions, no specific frequencies are as- dio, a newfangled device you could plied it to themselves. A reasonable signed to them. This considerable build at home that might enable you explanation? flexibility makes it possible for radio to converse with other owners. The Finally, here's possibility four: Several amateurs to communicate with all home-built radio came to be referred catch -all possible origins are sug- areas of the world at different times of 46 to as the "Home Amateur Mechanic" gested by Steve Mansfield, NIMZA, day and night. Amateurs worldwide

AmericanRadioHistory.Com The FCC's amateur rules are found have to meet internationally - WELL -KNOWN RADIO agreed AMATEURS in Part 97, Title 47, of the Code of on requirements. Radio amateurs AND THEIR CALLSIGNS Federal Regulations, referred to sim- aren't CBers; while both hobbies let ply as the "Part 97 regs." The FCC rules their members communicate with flesh out the details of just why there is other hobbyists, the similarity stops Amateur radio truly is a hobby that has something for almost everyone, an J an amateur -radio service-one with- there. CBers (at least in the U.S.) do not people of all ages, colors, religions, an J out a strictly economic purpose. The have to meet any technical stan- economic status are bitten by the "h an rules emphasize the voluntary, non- dards and don't have to be licensed radio bug." Radio amateurs include re- commercial nature of the amateur - personally or have their stations regis- tirees, students, young people, mechanics, technicians, homemakers, radio service; the amateur's ability to tered with the government. doctors, engineers, pilots -just aboLt contribute to the advancement of the There also are many misconcep- anyone you can think of, in all walks of radio art in both the communication tions about hams. Such misconcep- life. and the technical phases; the ability tions may well discourage potential Some famous people are radio ama- to enhance international goodwill; amateurs from a license teurs, although most are just averags obtaining people who enjoy making new friends and the expansion of the reservoir of and participating in the hobby. These around the world. Listed here, in alpha- trained operators, technicians, and include the misconceptions that you betical order, are some well -known pe- electronics experts available to the have to learn Morse code to get any sonalities, past and present, who were, nation. kind of amateur license; you have to or are, active amateur -radio enthus- asts: Some real responsibility is laid on be an electronics expert to pass the amateurs. By the nature of their free written exams; ham radio equipment Guitarist Chet Atkins, WA4CZD use of the spectrum, radio amateurs is overly Astronaut Ken Cameron, KB5AWP complicated and pro- Broadcast Newsman Walter generally are expected to serve the hibitively expensive; hams always in- Cronkite, KB2GSD public in times of need, such as during terfere with their neighbors' radios Astronaut Owen Garriott, W5LFL natural disasters. In fact, the Part 97 and TV sets; and hams must keep vo- Entertainer Arthur Godfrey, K4LIB regs state that a primary responsibility luminous records for FCC and various Senator Barry Goldwater, K7UGA Air Force General Francis "Butch' of the amateur service is to render other types of government bu- Griswold, KODWC public service communications to the reaucrats. Presidential offspring and formes general public. Importantly, radio All those statements are miscon- ARRL President Herbert Hoover, Jr-, amateurs, being licensed by the gov- ceptions: They simply are false. You W6ZH ernment, are expected to be a disci- don't need to know Morse for the King Hussein of Jordan, JY1 Air Force General Curtis Le May, plined and self -regulating service. Techniciar license, you don't have to W6EZV be an electronics whiz to pass the CBS News President Bill Leonard Clearing Away Misconceptions. As tests, ham equipment isn't all that W2SKE we've said, the amateur -service rules complicated or expensive, few hams Entertainer Ronnie Milsap, WB4KCG Husband -and -wife Astronaut team stress personal aims and non- pecuni- interfere with others' electronic equip- Steve Nagel, N5RAW, and Linda God- ary interest. While that means that ra- ment, and you don't even have to win, N5RAX dio amateurs are hobbyists, they are keep an on -the -air operating log of Broadcast Newsman Roy Neaé licensed by their governments and your contcc;s. (Hinkel), K6DUE' Entertainer Donnie Osmond, ex KA7EVD Entertainer Alvino Rey, W6UK Astronaut Dick Rutan. KB6LQS can exchange messages by voice, Morse telegraphy, television, radio - teletype (RTTY), radio facsimile (FAX), satellite, and a bevy of sophisticated digital modes.

Closer to Home. In the United States, the Federal Communications Com- mission (FCC) regulates the amateur - radio service, and you need a license to operate (we'll deal with how to get a license later on). The service offers a unique opportunity for training, inter- communications, and technical in- vestigation for qualified people interested in radio-once again, to those with a personal aim and without pecuniary interest. Amateurs may de- "Certificate chasers" or "wallpaper collectors" seek awards from a variety of sign, construct, modify, and repair organizations. One is the 10 -10 International Net organization, which focuses on 10 their own equipment. meters. A 10 -10 hamfest booth is shown here. 47

AmericanRadioHistory.Com What Do Hama Do? Now that we traffic, offering public -service com- ing contact verification cards (QSLs) know just what radio amateurs are, munications in emergencies, socializ- as the final step in documenting their we're free to wonder if they really do ing (with eyeball -to- eyeball contact), QSOs or contacts. Consequently, sim- more than just "talk on their radios." and much more. So, then, just what do ply getting on the air and commu- While most amateurs do, in fact, talk a hams do? Let's take a look at some 17 nicating with other amateurs by good deal using their radio equip- of those facets in detail. Among other voice, Morse code, and computers is ment, there also are many diverse things, radio amateurs: the basic goal of most people who (and fun) "cultural aspects" of ama- 1. Communicate and Operate: As study to obtain an amateur -radio li- teur radio besides yakking into an we will see shortly, there are many cense. open mike things that radio amateurs do. But the 2. Offer Public and Community You'll find the multifaceted aspects most basic activity that almost all Service: The concept of service to the of amateur radio include competitive hams participate in is ordinary, two - public is one of the justifications for contesting, certificate chasing (earn- way, on- the -air operating -which isn't amateur radio's existence in a spec- ing operating awards), "rag chewing" broadcasting to the public, but com- trum that's increasingly crowded and (engaging in ordinary conversation), municating with other radio ama- valuable. The public has come to ex- experimenting and building equip- teurs. pect amateur -radio operators to fill in ment, chasing DX (amateurs in distant Most hams like to communicate, to when the communications chips go foreign countries), handling message "Work" other stations, offen exchang- down, or when private and govern- mental communications are over- VOLUNTEER EXAMINER COORDINATORS whelmed, as they often are during There are 16 volunteer examiner coor- ARRL /VEC and the W5YI -VEC, in- natural disasters and other devastat- (VEC) dinator groups authorized by the cluded in the listing, below. Note the ing emergencies. The government Federal Communications Commission multiple day (D) and night (N) tele- and the public alike consider ama- (FCC), although some of these groups phone numbers listed for some VECs; are small and offer only infrequent ex- many of them are individual volunteer teur -radio operators to be valuable amination opportunities. The two main members' home telephone numbers. community resources. VEC groups operating nationally are the Amateurs were early supporters of American Radio Relay League and The Milwaukee Radio Amateurs Civil Defense (CD). CD burst onto the VEC Club, Inc. scene around 1950, once the public 225 Main Street P.O. Box 25707 realized that the Russians had "the Newington, CT 06111 Milwaukee, WI 53225 bomb." By 1952 amateurs by the thou- Tel. 860 -594 -0300 Tel. 414 -466 -4267 sands had volunteered their stations Anchorage Amateur Radio Club Mountain Amateur Radio Club to emergency communications un- 2628 Turnagain Parkway P.O. Box 10 FCC Anchorage, AK 99517 Burlington, WV 26710 der the -sanctioned Radio Ama- Tel. 907 - 786-8121 (D), Tel. 304 -289 -3576 or teur Civil Emergency Service (RACES). 907- 243 -2221 (N), 301 -724 -0674 RACES still exists as a special type of 907- 276 -5121, or volunteer amateur -radio operation. 907- 274 -5546 PHD Amateur Radio Association, Inc. Today it's sponsored by FEMA, the Central Alabama VEC, Inc. P.O. Box 11 Federal Emergency Management 1215 Dale Dr. S.E. Liberty, MO 64068 -0011 Agency, and it focuses on civil pre- Huntsville, AL 35801 Tel. 816- 781 -7313 Tel. 205- 536 -3904 paredness for local, regional, and na- Sandarc -VEC tional civil emergencies. Golden Empire Amateur Radio P.O. Box 2446 Public- service Society La Mesa, CA 91943 -2446 communications P.O. Box 508 Tel. 619 -465 -3926 take many forms today. Hams offen Chico, CA 95927 provide communications for acci- Sunnyvale VEC Amateur Radio Club Greater Los Angeles Amateur Radio PO. Box 60307 dents and hazards, brush and forest Group Sunnyvale, CA 94088 -0307 fires, earthquakes and volcanic erup- 9737 Noble Ave. Tel. 408-255-9000 tions, floods, hurricanes, weather Sepulveda, CA 91343 spotting and alerts, tornado warnings, Tel. 818-R92 -2068 or Triad Emergency Amateur Radio 805 -822 -1473 Club winter storm alerts, and more. Ama- 3504 Stonehurst Pl. teurs also participate in public -ser- Jefferson Amateur Radio Club High Point, NC 27265 vice events such as parades, sports P.O. Box 24368 Tel. 910 -841 -7576 New Orleans, LA 70184 -4368 events, festivals, fairs, exhibits, and Tel. 504- 737 -2315 Western Carolinas Amateur Radio special local events. Such "non- Society VEC threatening events" help amateurs Koolau Amateur Radio Club 5833 Clinton Hwy. 45-529 Nakuluai St. Suite 203 build communications skills that may Kaneohe, HI 96744 Knoxville, TN 37912 -2500 be put to good use when disaster Tel. 808- 235-4132 Tel. 615 -688 -7771 really strikes a blow. Laurel Amateur Radio Club, Inc. WSYI -VEC 3. Handle Message Traffic: Close- P.O. Box 3039 P.O. Box 565101 ly related to emergency communica- Laurel, MD 20709 -0039 Dallas, TX 75356 -5101 tions is another aspect of public Tel. 301 -572 -5124 (D), Tel. 817- 461 -6443 service, It's message 301 -317 -7819 (N), or 301 -588 -3924 or traffic han- 48 dling developing expertise in han-

AmericanRadioHistory.Com dling routine messages. While on the surface "third party" traffic handling for others may not seem glamorous or important, it's good experience for handling serious, life- and -death messages during disasters and other emergencies. While real -time digital communications, especially packet radio and AMTOR (AMateur Teleprinting Over Radio), have changed somewhat the nature of traffic handling, much message traffic still is passed using traditional modes, Morse code, and voice. Most amateur messages are handled through formally organized traffic networks, such as the ARRL's National Traf- fic System (NTS), which consists of over 500 amateur nets. Messages are handled by net members checking in to place mes- If you find it difficult or impossible to operate ham gear effectively from a crowded sages Into the system, or to take out apartment or condo location, you may want to seriously consider equipping a vehicle messages for delivery in one's local with a radio setup. area. Such messages directed to members of the general public usually are delivered by telephone. 4. Chow fM Rag: It's no sin for you to be a rag chewer -to talk at length about the ordinary things non -amateurs talk about, such as the weather, sports, politics, and other "In good taste" topics. While extended rag chewing is considered by some amateurs to be "yakking" that wastes valuable spectrum space, "chewing the rag" Is a valid technique in the use of amateur radio in the hobbyist sense: It encourages friendly QSOs of more substance than today's all- too -fre- quent "hello -good -bye" type of contact. Rag chewing is such a sufficiently valid purpose That the ARRL even of- Hamfests and radio flea markets are popular amateur activities. The core activity of fers an operating award, the Rag many hamfests is their flea market or swap meet area where amateurs buy, sell, and Chewers' Club (RCC). Because of Its swap old and new equipment and parts. ease of attainment, It's often the first operating award new operators seek. ment, and exchanging QSL cards with ference-offen very tricky and diffi- To obtain the RCC award, all you have those stations. Most hams agree that cult when a truly "rare one" suddenly to do is rag chew on -the -air for at DXing, especially on the long -haul HF emerges on a crowded ham band. least a half -hour, and request the bands, is one of the most satisfying Many DXers get the ultimate thrill award from the ARRL (you don't have and rewarding aspects of amateur out of becoming DX themselves: par - to be a member). radio -and it's also one of the most ticipating in a "DXpedition" to some 5. Work DX: Working DX, con- avidly pursued aspects of the hobby. remote, rarely worked, highly desir- tacting other amateurs in distant (or If you want to successfully work DX able location. Actually being the rarely contacted) foreign countries, is on HE precision techniques are in- much -sought-after foreign DX strikes one of the oldest ham pursuits. Even in volved, especially when running QRP the fancy of many, although planning these days of easy worldwide Internet, (low power) with simple antennas and anc preparing DXpeditions is difficult, satellite, and telephone communica- no- frills, basic equipment. There's also time -consuming, and expensive. Too, tions, there still is something magical a premium on good DX etiquette that many of the "choice" (read "remote and thrilling about communicating should always be exercised in pursu- and rare ") locations are dangerous to with stations halfway around the ing DX QSOs, so as not to cause other visit and operate from, either due to earth, using your own radio equip- operators undue frustration and inter- physical conditions (rocky reefs, 49

AmericanRadioHistory.Com 8. Tinker and Experiment: Once you overcome the hurdle of obtaining your amateur-radio license, you can elect to be an "appliance operator" if you so choose. Although historically radio amateurs have been known for their technical skills, often building at least some of their equipment, there's nothing that says that you must do so-the choice is yours. But many amateurs, even those who don't have any special electronics skills, enjoy tin- kering and experimenting with their antennas, equipment, and ham - shack accessories -anything but leaving well enough alone. With today's technologically sophisticated radio equipment, it may no longer be practical for you to build major pieces of gear, such as a re- Communicating through amateur -radio satellites, which are akin to orbiting signal ceiver, transmitter, or transceiver. But repeaters, is one of the "hot" areas in amateur radio, one that holds much promise for you can build smaller items (such as the future. Here amateurs at a hamfest demonstrate operating techniques and accessories of various kinds). Most procedures. major amateur journals are chock full of realistic construction projects, storms, lack of water, etc.) or unstable cialized awards, issued by the ARRL many of them geared to the elec- political realities (banditry, insurrec- and other organizations. These tronics beginner using simple tools. tion, and the like). But, as many DX awards cover an amazing variety of 9. Operate Using Low Power hounds will tell you, these obstacles feats and accomplishments, such as (QRP): Why operate QRP that is, use are just part of the challenge of being contacting a given number of U.S. low power, especially if you don't a true DXer. counties, Swiss cantons, Russian have to do so? Isn't it something like 6. Seek Operating Awards: The oblasts, or members of the award's competing in the prize ring with one pursuit of amateur operating awards sponsoring organization. hand tied behind your back? Possibly is a major part of what many hams do. 7.. Compete in Contests: Many ra- so, but many hams enjoy the added To them, just working or communicat- dio amateurs are very competitive in- challenge. Some of the advantages ing with certain stations or classes of dividuals who simply like to win at 'Plea- power" operators find, in addi- stations isn't sufficiently satisfying. whatever they do, hobbies included; tion to the basic challenge factor, in- They're motivated to document their they're referred to as contesters. An clude minimum expense, small operating skills in various categories amateur radio contest is a competi- equipment size and weight, easier by seeking paper awards, trophies, tive operating event -much like a emergency and portable operation, and plaques. sporting event-held between rivals practical long -term battery life, If you're a "certificate chaser" or over a predetermined operating and -not the least -a significant "Wallpaper collector," you seek a vari- period. For a hobby, however, the scoring advantage in many radio ety of awards from American, foreign, main goal of contests is (or at least contests. and international organizations, should be) that the participants enjoy On the flip side, you may find that clubs, and publishers. Probably the themselves, and at the same time commercial QRP equipment selec- most sought -after award in amateur help to advance the radio art and tion is limited, and available equip- radio is that of the ARRL's DX Century increase their expertise. ment often is not only low in power but Club (DXCC), essentially for docu- There are countless contest classi- also is primitive in terms of features. mented communication with radio fications. You'll find domestic contests, Too, voice communications are more amateurs in at least 100 different in which the objective is to work as difficult using QRI? meaning that CW countries. Many special classifica- many stations as possible, such as the (Morse code) and some digital tions, variants, and "endorsements" ARRL's Sweepstakes (SS); VHF /UHF con- modes are the more practical modes. are available for this highly coveted tests, focusing on the bands above 50 QRPers are a hardy band, and to and respected DX award. MHz, such as the ARRL's VHF QSO Par- cater to them there's a special interest There also are awards for such di- ties and the CQ Magazine VHF WPX group, the QRP Amateur Radio Club verse activities as code proficiency, Contest; beginner- oriented contests, International, Inc. (QRP ARCI), whose working all states (WAS) and con- such as the ARRL's Novice Roundup; motto is "power is no substitute for tinents (WAC), VHF /UHF operating and numerous specialized or lo- skill." The club, founded in 1961, has as (VHF /UHF Century Club, or VUCC), calized competitions, most of which its purpose the joining together of working all radio zones (WAZ) and call - require you to work members of a those amateurs who enjoy running 50 sign prefixes (WPX), and many spe- particular group. low power. The organization encour-

AmericanRadioHistory.Com ages QRP by means of various awcrds Prosigns are special telegraphic ex- three -day affair held in the spring, programs, activities, and contests. The pression and procedure symbols, one that draws some 30,000 atten- QRP ARCI also publishes The QRP such as SK (end of transmission) and K dees each year. Quarterly newsletter and holds reg- (go ahead) that have been word -sav- You'll find that hamfests indeed are ular on- the -air QSO parties. ing shortcuts at least since the earliest popular eyeball -to- eyeball activities. 10. Enjoy their Hamshacks: All am- days of wireless. The voice -equivalent The main activity at most is the radio ateurs, regardless of how elaborate prowords clear, break, over, affir- flea market or swap meet area where their radio stations may be, have their mative, negative, and roger are self - people buy, sell, and swap radio gear located in their "radio explanatory. However, contrary to equipment, parts, and components. hamshack." Early shipboard installa- popular belief and classic war movie They also include a variety of educa- tions and shore stations tended to be usage, "roger" simply means "I have tional activities with beginner sessions, located in isolated radio rooms or received your last transmission cor- technical seminars, and operating buildings, and for good reason. That rectly," but doesn't mean "yes" or "af- presentations being featured. was because the noisy spark transmit- firmative." Best of all, many hamfests feature ters produced an ear -shattering The Q -Code is a three- letter series supervised on -site amateur radio ex- crash every time the key was de- of shortcut codes that has been in use aminations. Volunteer Examiners pressed, disturbing all within earshot. at least since 1912. The Q -code was (VEs) -amateurs who volunteer their If the early spark -rig amateur wasn't designed to overcome language services as test-givers--are certified banished to a distant outbuildirg, barriers by ship operators as they by the Federal Communications cabin, or detached structure, he was communicated among themselves Commission (FCC) to administer all at least relegated to space behind and with shore stations. Most of the classes of amateur radio licensing the basement furnace or to an attic original codes still are in use today. exams (more on testing later). enclave where he wouldn't disturb Some of the more popular Q -codes 13. Act as "Eimers ": Beginning ra- the family. Today, however, you'll find favored by hams include QTH (loca- dio amateurs always have looked to modern, silently efficient amateur station), QRM (interference), QSL (ac- more experienced operators, or tions housed in almost every con- knowledgment of receipt), QSO " Eimers" (as we call them today), to ceivable spot in the home. But, even if (contact), and QST (calling all radio provide guidance and help. In the that spot is the most luxurious and amateurs). early days of amateur radio, most comfortable part of your home, it's still 12. Socialize at Hamfests and grizzled "old timers" gladly accepted called the hamshack-and that holds Swap Meets: A hamfest is a grand that responsibility, helping youngsters true even if the spot is really in your meeting of radio amateurs, ranging eager to get their licenses by setting boat, airplane, or automobile. from small get -togethers to major ra- good examples of proper operating 11. Talk a Funny Language: Just dio conventions. But the term covers a practice and providing Morse -code about every profession (and most lot of ground. Some are small, attract- and technical assistance. The begin- hobbies) has its own distinctive and ing only a few hundred visitors. Others ner usually was able to get help with a sometimes impenetrable jargon. Am- attract tens of thousands of atten- low- budget project when it was ateur radio is no exception: There's no dees, such as the Dayton Hamvention, needed. end to "hamspeak" buzzwords. Most which really is a hamfest event that's in In those days, if you were an ama- of those have their origin in the need a class all by itself. The largest U.S. am- teur or prospective amateur, you ex- to create a shorthand to simplify ateur radio convention by far is a perienced a special bonding and Morse transmissions, one that could have the same meaning regardless of operators' languages. The geness Greetings From One of the CO Gang! and usage of this vernacular is interesting, so let's unscramble some of the ANTENNAS & ACCESSORIES EDITOR lingo. The popular general call or attention signal made by amateurs, CQ, originated with 19th century tele- W8FX graph systems. It originally meant that Karl T. Thurber, Jr. all telegraph offices should be ready SERVING THE 289 Poplar Dr., Milibrook, AL 36054 ACTIVE to receive a message. Today, CQ HAM CO Zone 4 Elmore County SINCE 1945 means that you're inviting anyone who hears you to reply to your call. CONFIRMING 2 WAY OSO PSE OSL TNX The term 73 "ties the ribbons on" o' CALL DATE UTC BAND MODE RST RIG, PWR., ANT. ends a contact, or QSO. It still is a pop- DAY MONTH YEAH ular, all- purpose amateur salutation, in particular meaning best regards or -bye. A 73 -like feminine varia- good A W4MPY Gill tion is 88. The term means "love and kisses" and is used between amateurs For many radio amateurs, exchanging a QSL (verification) card is the final courtesy of of the opposite sex. a two -way contact. Shown here is the author's personal QSL card, 51

AmericanRadioHistory.Com FOR MORE INFORMATION specialized amateur radiosport for French Guiana, set for September VHF and UHF operators is radio direc- 1996. More information is available 10-10 international Net, Inc. tion finding, or RDFing (sometimes from the Radio Amateur Satellite Cor- 643 N. 98th St. #142 known as hidden -transmitter hunting, poration (AMSAT). Omaha, NE 68114 fox hunting, or bunny hunting). In RDF- 16. Communicate Digitally: Ama- Amoco Corporation ing, someone hides a radio transmit- teur radio is more exciting than ever, 224 East Second Street ter in an inconspicuous place and the due mostly to the effects of digital - Mineola, NY 11501 radiosport participants each try to be based operating modes. Today's Dsyton Hamvention the first to find the hidden transmitter. hamshack typically is equipped with P.O. Box 964 Such contests can be very competi- a PC and takes advantage of several Dayton, OH 45401 -0964 tive and popular group events at ra- state -of- the -art communications Gordon West Radio School /Radio dio club outings and at hamfests. techniques. Amateur Calibook You'll find RDFing to be both an art Indeed, a host of digital -based P.O. Box 2013 Lakewood, NJ 08701 and a science. There's a serious side to technologies has caused amateur - RDFing that relates to improving your radio hamshacks to change tremen- HAL Communications Corp. skill at finding transmitters that are en- dously, and the is accelerating. 1201 W. Kenyon Road pace P.O. Box 365 gaged in illegal practices, such as We're now halfway through the de- Urbana, IL 61801 jamming repeaters or unlicensed in- cade in which digitized, comput- Hambrew Magazine truders (often using stolen trans- erized amateur -radio communica- P.O. Box 260083 ceivers) on the ham bands. tions takes off and positions the hobby Lakewood, CO 80226 -0083 15. Communicate via Satellites: to thrive and grow in the next century. HighText Publications, Inc. So far, we've mostly covered activities Packet radio took amateur radio by 125 N. Acacia Avenue hams traditionally have enjoyed. Now, storm in the 1980s. It's a high- speed, Suite 110 it's time to look to the future. Commu- frequency -space efficient mode that Solana Beach, CA 92075 nicating through amateur -radio sat- lets you digitally send, receive, store, Kantronics ellites, which are akin to orbiting signal and forward messages. Ifs similar to 1202 East 23rd Street repeaters, is one of the current "hot," RTTY, but packet data is sent at a Lawrence, KS 66046 -5006 growing high -tech areas in amateur much higher speed, and in a "con- Media Mentors, Inc. radio. nected" (telephone -like), nearly inter- P.O. Box 131646 Since 1961, when the first Orbiting ference -free, error -checking, and Staten Island, NY 10313 -0006 Satellite Carrying Amateur Radio (OS- networked fashion, especially on QRP Amateur Radio Club CAR) was launched, amateurs have VHF /UHF international Mike Bryce, WB8VGE communicated via satellite over But digital radio is more than just 2225 Mayflower N.W. thousands of miles using very high fre- packet. Several related ARQ (auto- Massilon, OH 44647 quencies (VHF) and ultra high fre- matic repeat request) modes are Radio Amateur Satellite Corporation quencies (UHF), wavelengths tradi- popular on HF where packet reliability P.O. Box 27 tionally used for short distances. Today leaves something to be desired. AMa- Washington, DC 20044 you can make international QSOs via teur Teleprinting Over Radio (AMTOR) Tiare Publications satellites, using relatively simple is an error -checking mode that mini- P.O. Box 493 equipment. mizes interference (QRM), fading Lake Geneva, WI 53147 A new era in long- distance ama- (QSB), and static (QRN). VIS Study Guides teur communications dawned in The German -developed Packet 119 Comanche Drive 1983, when the first Phase 3 satellite, Teleprinting Over Radio fills a void in PO, Box 17377 OSCAR 10, was launched. But today digital communications; PacTOR has Hattiesburg, MS 39404 there is only one major amateur -radio been likened to an enhanced AMTOR The WSYI Group, Inc. satellite, OSCAR 13, that's capable of that combines the best features of P.O. Box 565101 providing consistently reliable inter- AMTOR with HF packet radio. And then Dallas, TX 75356 -5101 continental amateur communica- there's the highly efficient CLOVER were treated fraternally. Unfor- tions. Unfortunately, it soon will plunge mode, named after its clover -like . tunately, as the hobby has grown into the atmosphere and be de- wave pattern; popularized by HAL much larger and become "more pro- stroyed. Communications, it's becoming a fessional" over the years, at least The under -construction Phase 3D popular mode on HF. Ditto for G -TOR, some of this camaraderie has evapo- satellite, a replacement for OSCAR 13, a high- throughput HF system de- rated. But there still are Elmers out is the largest and most advanced am- veloped by Kantronics. á there to help you get started; you just ateur satellite ever built. It's aimed Today, the heart of many digitally rn have to look harder to find them at squarely at reducing the cost and equipped hamshacks has evolved ° radio clubs, at hamfests, and on the complexity of satellite -capable ama- from the relatively simple TNC (termi- ñ air. You can continue the tradition: If teur stations, plus adding new fre- nal node controller) required by someone mentors you as an Elmer, quency and data choices. The launch packet to a new -generation multi - O when you become experienced, you of Phase 3D is to be aboard the Euro- mode data controller that lets you use should become an Elmer for others. pean Space Agency's (ESA's) Ariane 5 up to a dozen or so digital modes of 52 14. Radio Direction -Find: A rather vehicle from the ESA complex in (Continued on page 104)

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AmericanRadioHistory.Com BUILD A DELAYED SWEEP ADAPTER

Add more versatility to your oscilloscope with this simple and inexpensive plug -in adapter.

BY SKIP CAMPISI

If you're like a lot of other hobbyists oscilloscope's trigger input jack in the cilloscope, whose channel -1 output is out there, chances are you have a external trigger mode. about 25 millivolts per vertical division limited budget for test equipment. With the delay set on the Adapter of the signal display. Assuming a nor- Therefore, if you recently bought an for slightly less than the waveform's mal display of about six divisions, the oscilloscope you probably couldn't time period, the sweep will trigger be- level control provides a range of justify that extra two- or three -hundred fore the next cycle, thus allowing you -* 150 millivolts. You can easily change dollars for a unit with built -in delayed to see the leading edge of a pulse that range to suit your scope output sweep. But how often since that pur- waveform. The leading edge area by adjusting the ratio of R3 (15,000 chase have you needed to look at the may then be expanded by increasing ohms) to R4 (470 ohms); however, leading edge of a narrow, low duty- the scope's sweep speed, while ad- maintain the ratio of R5 (100,000 cycle pulse, at high sweep rates? Or justing the delay on the Adapter to ohms) to R4 (470 ohms) for proper perhaps you have needed to expand maintain the position of the trace. Of hysteresis. Resistor R1 (51 ohms) "termi- a waveform to look for a "suspected" course, any part of any waveform can nates" the 50 -ohm cable from the oscillation, but just couldn't stabilize be viewed and expanded in a similar channel -1 output jack. the trace. fashion. A 7473 TTL dual J/K flip -flop, IC2, is Thanks to the current trend in os- Built as described, the Delayed configured in its toggle mode to di- cilloscope designs, most scopes are Sweep Adapter will perform as well as vide the input frequency by Iwo. That now equipped with a channel -1 out - if you had spent two- to three -hun- ensures that IC3, a 74121 TTL monosta- put jack, which provides a "sample" of dred extra on your scope. However, it ble multivibrator, will function accu- the channel -1 input waveform. The will only cost you twenty to thirty dol- rately over the input waveform's full jack is normally a BNC connector lo- lars to build! time period. The pulse output from IC3 cated on the rear scope panel, and is is coupled to the trigger -input jack of designed to drive a standard 50 -ohm Circuit Description. The schematic your oscilloscope, and the "slope" is cable. Because the input signal is at- for the Delayed Sweep Adapter is selected via S2 to match the slope tenuated via the scope controls, no shown in Fig. 1. Power for the circuit is selected on your oscilloscope. other attenuators are necessary for provided by a dual -polarity, 5 -volt Potentiometer R9 allows fine posi- external instruments. That makes de- supply, which we'll deal with a little tioning of the trace, and potentiome- signing add -on instruments much sim- later on. ter R7 allows the output pulse width pler. An LM360 high -speed comparator selected to be multiplied by a factor One such add -on, which will solve (IC1) with complementary TTL outputs of " x 1" to over " x 2.5." Switch S1 lets the problems just presented, is the is at the heart of the circuit. A trigger - you select the desired pulse width by

Delayed Sweep Adapter described in level control, potentiometer R2, allows switching in C8 through C13, in a 1 -2 -5 this article. It is essentially a monosta- the Adapter to trigger on any part of sequence. Although the schematic ble multivibrator that is triggered via the waveform being displayed. only indicates six switch positions for the "sample" at the channel -1 output. With the values shown, the circuit clarity, more can be added if desired. 56 The Adapter output is then fed to your functions well with a Hitachi V -212 os- The Adapter circuit was designed to

AmericanRadioHistory.Com PARTS LIST FOR THE F16 J1 +5V C2 10K +5V DELAYED SWEEP ADAPTER IN 1 (Fig. 1)

)1I C3 SEMICONDUCTORS

7 ICI -LM360 high-speed comparator, +v integrated circuit R2 IC2 TTL dual J/K flip -flop, 10K -7473 integrated circuit LEVEL F13 K CR IC3 TTL monostable R1 -150mV- 15K CR -74121 510 +150mV ßD multivibrator, integrated circuit C5 ) C4 1 RESISTORS 1 a )II+ (All fixed resistors are 1/4-watt, 5% 1C2 R4 R5 units.) 7473 -5V 4700 7. 100K RI -51 -ohm R2- 10,000 -ohm linear taper

14 potentiometer, panel -mount +5V R3- 15,000-ohm C6 I+ Al 1C3 R4-470 ohm 4 C7.1 I A2 74121 R5- 100,000-ohm T R/f_ R6-10,000-ohm F17 GO O 5 linear taper 25K c R7- 25,000 -ohm 6 potentiometer, panel -mount -4 MULT 10 xl -x2.6 r r R8- 13,000 -ohm C13 R9- 2500 -ohm linear taper f ; 500µs potentiometer, panel -mount 200gs C12 CAPACITORS -4 .02 F18 CI, C5, C6 -µF, solid tantalum r -I 13K S 010Ogs S1 50µs C11 C2-C4, C7- O.1 -p,F, ceramic -disc DELAY O I 01 C8 0.001 -RF, ceramic -disc (see S2 20µ N o- text) SLOPE O C10 logs C9- 0.002 -uF, ceramic -disc (see J2 005 text) OUT C8 F19 C9 C10- 0.005 -p.F, ceramic -disc (see 2.5K 001 .002 r4 FINE ADJ text) ClI- 0.01 -uF, ceramic -disc (see text) C12- 0.02 -uF, ceramic -disc (see Fig. I. Here's the schematic for the Delayed Sweep Adapter. With the values shown for text) C8 -C13, the delay range is 10 -µs to 500 -µs, but that can be changed or expanded C13-O.05 -uF ceramic -disc (see quite easily. text) ADDITIONAL PARTS AND operate on an external ± 5-volt, 100 - that the polarized capacitors are ori- MATERIALS milliamp power supply, to avoid 60 -Hz ented properly. Next, solder short, J1, J2 -BNC jack, panel mount Sl rotary switch pickup in the unit. A schematic di- insulated wire leads to accommo- -IPI2T S2 -SPDT miniature toggle switch agram of the supply is shown in Fig. 2. date connections to the potentiome- Perforated board, aluminum Transformer T1 steps down the volt- ters, switch S1, and jacks, which will be enclosure. BNC cables, IC age from an AC outlet to about 12 mounted to the enclosure. (Switch S2 sockets, control knobs, coaxial volts. That AC is then rectified by BR1 will also be mounted to the cabinet, cable, wire, solder, hardware, etc. and fed to a +5 -volt regulator (ICI) but shielded cable must be used to and a -5 -volt regulator (IC2) to pro- connect it, as we'll mention in a mo- you'd like to be able to disconnect the vide a true bipolar supply. ment). Adapter, you might want to consider The enclosure used for the author's adding a power jack to the Adapter Construction. The author's pro- prototype was an aluminum cabinet at this time. Make sure it's a 3- contact totype for the Delayed Sweep Adapt- measuring 15/8 x 21/8 x 81/2 inches, jack to accommodate the + 5 -volt, er was built on perforated board but you can use any suitable shielded -5 -volt, and ground connections. using point -to -point wiring, but you case. Mount J1 on one end and J2 at Mount the circuit board inside the can use any suitable method of proj- the other end. The potentiometers enclosure, near S1, and make the ect building that you prefer. Begin as- and switches can be arranged on the connections from the wire leads to sembly by mounting sockets for the face of the cabinet; make sure S2 is the panel- mounted components. Sol- three ICs. located close to J2. der resistor R1 directly onto J1. Con- Wire the fixed resistors (except for If you plan on building the power nect J2 to S2, then use two coaxial R1) and capacitors (except for supply for use only with the Adapter, cables (with one end of each shield C8 -C13) to the IC sockets, using short you can leave an opening to run grounded) to connect the switch ter- leads for their connections. Be sure power leads through. However, if minals to pins 1 and 6 on IC3. 57

AmericanRadioHistory.Com T1 r shielded cable is connected to a - IC1 1 matching 3- contact plug. 781-05 C.T. 1_ +I

1 1

1 1 G Operation. Using standard BNC -ter- Cl 1+ C3 R1 I I 330 1.8K minated cables (RG -174 RG L_ - -I .1 or -58), BR1 connect J1 to the channel -1 s- output 50PIV C2 + jack on your oscilloscope, and J2 to 1A LED1j 330 1. ACON the trigger -input jack your G 1 on scope. Then power up the Adapter. 102 117 VAC With your scope set up for internal 791.05 S1 -a S1 -b triggering, apply the signal- to -be-

ON tested to your scope's channel -1 in- -5V O 0 OFF put, displaying one cycle at about six vertical divisions of height. Note the GND O approximate time period of the sig- LED2 R2 DC ON nal. Set up the Adapter in the follow- 'SEE TEXT 1.8K +5V 0 ing manner: Find the position of R9 that yields Fig. 2. If you don't have a bipolar 5 -volt supply, build this simple circuit to power -up accurate time -delay indications (that your Adapter. will most likely be the center of rota- tion) and leave it set there. Set S1 and Mount C8 through C13 (and any R7 to the approximate signal time PARTS LIST FOR THE other range capacitors you plan on period you would like. Then set S2 to ± 5-VOLT POWER SUPPLY using) directly from the appropriate match the slope (Fig. 2) setting on your os- terminals on S1 to a bit of stiff wire, cilloscope. (Note: Reversing the set- which should connect to R9 and pin SEMICONDUCTORS ting of S2 will give you a normal, non - 11 of IC3, keeping those leads as short IC1 -78L05 +5 -volt regulator, delayed display.) as possible. When choosing capaci- integrated circuit Now switch the oscilloscope's trig- tors for C8 -C13, keep in mind that the IC2-79L05 -5 -volt regulator, ger source to the external setting, and circuit shows a range of 10 microse- integrated circuit adjust R2 on the Adapter for a stable conds through 50 microseconds of BR1 -1- ampere, 50 -PIV bridge trace. Rotate R7 back and forth; note delay. However, you may select any rectifier how the waveform trigger point can Light- emitting range you desire or expand the LEDI- diode, red be moved to any location on the LED2- Light- emitting diode, yellow range. It's possible to expand the trace. Select the section of the trace range because the switch used for S1 ADDITIONAL PARTS AND to be expanded, and move it to the is a 12- position unit, and only six posi- MATERIALS left side of the CRT screen by adjusting RI, R2 -1800 -ohm, %a -watt, 5% tions are used as shown in Fig. 1. R7. Reset S1 if needed. You may now resistor Here's how to choose appropriate increase the scope's sweep speed to Cl, C2- 330 I6 -WVDC, range capacitors: As the range pro- -4 expand the section desired, adjusting electrolytic capacitor gresses in a 1 -2 -5 fashion, so do the C3, C4- 0.1 -µF ceramic -disc R9 as needed to maintain position on capacitor values. As indicated on the capacitor the screen. schematic, C8 (0.001 µF) equals 10 µs, T1 -120- to I2.6 -VAC, 0.2- ampere, That method can be used on any C9 (0.002 ILE) equals 20 µs, 010 (0.005 center-tapped transformer type of waveform: pulse, sine, square, µF) equals 50 Rs, C11 (0.01 µF) equals SI -DPDT miniature toggle switch triangle, etc., whether unipolar or bi- 100 µs, and so on. If, for instance, you Perforated board, enclosure, wire, polar. The only limits to the expansion desire ranges of 1, 2, and 5 microse- solder, hardware, etc. of the trace are the scope's available conds, the values to use would be 100 trace intensity, and the "jitters" in the pE 200 pE and 500 pF. If you desire knobs on the control shafts, and close display caused by unequal cycle ranges of 1, 2, and 5 milliseconds, the up the cabinet. times in the signal itself. values would be 0.1 µE 0.2 µE and 0.5 Build the power supply on a piece µF. (The capacitance is equal to the of perforated board as well. Connect delay divided by 10,000.) Use high - the components as shown in the quality capacitors for timing stability. schematic, making sure to match all To complete assembly, insert the ICs the indicated polarities. Mount the into their sockets. Before you close up transformer in an enclosure, and then the enclosure, calibrate R7 as follows: connect the board to it. Be sure to The x 1 position should be equal to 0 close the supply case before you plug ohms, x 1.5 should equal 7150 ohms, the circuit in. x 2 should be 14,300 ohms, and so on. The supply can be connected to Mark and label your cabinet appro- the Adapter with a 2- conductor priately. Double -check all of your wir- shielded cable. If you mounted a jack And this is where Herb makes things - 58 ing and interconnects, install control to the Adapter, make sure the lumps of solder, bits of chips...

AmericanRadioHistory.Com Looks Like It's Mailbag Time! BY MARC ELLIS

My plans for this month were to communications receivers and the 8.6:1 -close enough! move right along with the Star Bogen LS -330 PA amplifier. Filament transformers aren't exact-

Roamer restoration-until I took a look Joseph R. Veltri (249 Kingwood ly designed for hi -fi response, but then at my rather full "in" box. It seems like Street, Morgantown, WV 26505) is neither are small audio transformers. (where does the time go ?) we haven't looking for information on a one -tube And the filament transformer's power published any reader mail for about RCA Radiola. He can't read the model rating (6.3x1.2 =7.56 watts) was more four months. There are many rather number. Anyone want to correspond than enough to handle the audio interesting letters, so let's dive right in! with Joe about this rare set? power developed by the little set. Bill Dr. S. Sadik (7321 Harps Mill Road, says that the substitute transformer HAVES AND NEEDS Raleigh, NC 27615 -5418) needs a worked out quite well. Robert D. Laszlo (11287 Wildwood schematic and service information for Dr., Osceola, IN 46561 -9371) would a circa -1929 Thomas Edison, Inc. KEEPING CAPS like construction information and a (Orange, NJ) Receiver Unit Type 7R AUTHENTIC LOOKING parts source for a simple "cat's and its accompanying power unit Larry Scalph (Tacoma, WA) won't whisker" crystal set. His wife is a first- (Type 7P). John H. Rodriguez (123 turn on a long- unused vintage radio grade teacher, and he'd like to build Colonel's Lane, Weymouth, MA 02189 without replacing all electrolytic and one for her class. or call collect at 617- 331 -4874) would paper capacitors. But he likes to keep like a repair source for a two -speed the caps looking authentic, so he hysteresis motor. mounts the replacements inside the Dave Eley (17294 58th Avenue, shells of the originals. After removing Surrey, BC, Canada V3S 1K8) is still each old capacitor and cleaning it with looking for a Miller coil to complete his alcohol, he slits the shell lengthwise Theremin (see the May 1996 column). with a razor blade and removes it from

I didn't help him much by getting the around the "insides." Using wire ties, number of the coil wrong. What he he fastens the shell into its original needs is a Miller #695, not a #6905. cylindrical shape and coats the inside Dave also, quite reasonably, blames with fast -set epoxy. me for misprinting the Theremin Enthusiasts Club International's e-mail address. However, just to make sure

I'm not getting soft in my old age, I checked his original letter. Sorry, Dave, that last boo -boo is yours! Anyway, you can e-mail the Theremin Enthusiasts (do Barry Eso) at beso @cln.etc.bc.ca.

Larry Scalph's beautiful Zenith 85463 is shown SUBSTITUTE OUTPUT installed in its cabinet. TRANSFORMER Needing a 2500 -ohm primary /8- Here's the under -chassis view of Laos In addition to the Webster-Chicago ohm secondary output transformer in a restored Zenith 8S463. The capacitor shells arc wire recorder (Model 180 -1) and 10- hurry, reader Bill Stiles' (Hillsboro, MO) original but they have new capacitors inside. inch Sentinel black- and -white TV gaze fell upon a 6.3 -volt 1.2 -amp fila- (Model IU- 415 -CV) mentioned in our ment transformer in his junk box. Next, he removes the ties, inserts May issue, Craig Sellen (RR -1 58 -B Calculating the impedance ratio of the the new capacitor (metallized -film caps Box 1038, Waymart, PA 18472 -1038) required transformer (312:1), he took are used for their small physical size) is now offering a 3KP4 CRT as used in square roots to determine the needed and seals the ends with hot glue. "Off - Pilot pre -war and wartime experimen- turns ratio (17.7:1). In a power trans- white" glue sticks are best because tal TV sets. Interested? Make an offer! former, turns ratio is equal to voltage their color is similar to that of the origi- Craig is also looking for schematics For ratio, so the 117 -volt to 6.3 -volt fila- nal wax. Larry finishes the job by run- the Panasonic RF -4800 or RF -4900 ment transformer had a turns ratio of ning the hot end of his glue gun over 59

AmericanRadioHistory.Com the slit in the shell- camouflaging the the house was quiet, he could listen to slit by melting some of the original wax the programs from across the room. over it. Capacitors are removed, The G. M. R. Sensitivity and selectivity were quite rebuilt, and replaced one at a time to good. At night, he could hear several avoid confusion and wiring errors. Super- Heterodyne clear-channel stations (KXEL, KOIL, Replaced capacitors are positioned so Converter WLW, and others). With the ground that their slits are out of sight. disconnected, he could receive some Larry also fuses the primary of each with Remote Control of the major shortwave broadcasters, set's power transformer before return- such as Voice of America, Radio ing the chassis to its cabinet. The Moscow, Radio Havana, and Voice of added fuse might not be an authentic L © the Andes. touch, but someday it may well save 1 an expensive and difficult -to- replace READERS' transformer! PUZZLES SOLVED Radio historian Alan Douglas CRYSTAL SET (Pocasset, MA) identified Loren HAS FULL -WAVE Perkins'"ashtray radio," featured in the RECTIFICATION May issue, as a General Motors Gus Linja (Lake Linden , MI) tells us "G.M.R Super- Heterodyne Converter." that he's been building crystal sets The dual- function G.M.R converted since the early 1940s, and even back TRF radios into "highly selective, fine - then was intrigued by the extra power performing superheterodynes" and that might be available if a full -wave provided "remote control over all sta- rectifier was substituted for the half - tions in the full broadcast range." wave circuit that was typically used. Alan also ID'd Curt Wagner's "What The scheme wasn't practical then, is it ?" (also in the May issue) as some because it would have required four form of laboratory potentiometer - separate galena crystals with four sep- possibly a pH meter. Taking it a step arate cat's whisker adjustments. Once further, retired instrument technician/ semiconductor diodes became avail- field engineer Don Waltenberger able, however, he tried it (see Fig. 1). (Garrettsville, OH) is reasonably cer- Antenna Coil L1 and capacitors Cl tain that the instrument is a millivolt and C2 were salvaged from an potentiometer used to measure the Atwater -Kent battery- operated TRF; output of thermocouples employed for capacitor C3 is 0.05 -mFd; and diodes ' precise temperature measurements. D1 through D4 are germanium diodes. , THE BOAKE The G. M. R. Super -Heterodyne ANT HEADPHONES CARTER PHILCO Converter, newest achievement in Speaking of solutions to reader puz- radio, has a two -fold purpose. 1. It converts tuned radio frequency zles, we've had a very big response to L models into highly selective, fine - reader Ray Shetrone's (Ft. Meyers, FL) performing super -heterodynes. 2. It query regarding the flamboyant signa- provides remote control over all sta- ture on the dial of his Philco 38 -7 con- tions in the full broadcast range - sole. As was announced in an earlier a thirty -foot extension cord makes it column (thanks to information provided possible to place the converter wher- by Popular Electronics' art director ever it is most convenient. Here is a sensational new profit maker in radio Andy Duzant), the signature belongs to C2 that every present owner will want. Boake Carter, a well -known newscast- er of the 1930s whose broadcasts were t Price as flamboyant as his calligraphy. At one Fig. 1. This is the schematic for Gus Linfa's point in his career, Carter was spon- full -wave" crystal set. See the text for a description of the components. complete sored by Philco, and the following pas- sage (courtesy of Philco historian Ron A contemporary trade magazine ad for I& Ramirez) is taken from the 1937 Philco Capacitor Cl is for main tuning, G.M.R. Superheterodyne Converter (courtesy dealer catalog-which was quoting while C2 tunes the antenna circuit. Alan Douglas). Time magazine of April 13, 1936: With the set connected to a 100 -foot "Not only is Boake Carter currently wire antenna (50 -feet up at the highest so that Gus could operate a speaker the most popular of Radio's news corn 60 point), enough power was generated (through an output transformer). When continued on page 62

AmericanRadioHistory.Com DX LISTENING

Slovak Radio On the Air BY DON JENSEN

Slovakia is one of Europe's Today, Radio Slovakia International programs are aired to other parts of the newest countries, born on broadcasts in five languages, English, world at 0830 UTC, on 11,990, 15,460 January 1, 1993, with the dissolution French, German, and Russian, in addi- and 17,550 kHz; at 1630 UTC, and of what was Czechoslovakia. The split, tion to the native Slovak. The station's again at 1830 UTC, on 5,915 and 6,055 peaceful and democratic, brought staff produces eight- and -a -half hours kHz. Some of these may be audible in many changes to the two new coun- of shortwave programming, including a the US and Canada, although they are tries, Slovakia and the Czech half hour of English, seven days a specifically directed elsewhere. Republic. For many years, a single week. RSI's English programming to North shortwave entity known as Radio Programming begins with about America is aired at 0100 UTC on 5,930, Prague was the voice of a federated five minutes of news. The rest of the 7,300, and 9,440 kHz. Send reception Czechoslovakia. Suddenly, Slovakia half hour is a radio magazine, whose reports to Radio Slovakia International, was unrepresented on the shortwave highlights vary day by day. Some high- Mytna 1, 812 -90, Bratislava, Slovak bands. And so a new SW voice, the lights from RSI's schedule include: Republic. If you want to ring them up international service of Slovak Radio, Monday: sports, history, cultural, instead, the phone number for the came into being. and foreign -relations segments. English service is 011 -42 -7-498 -075.

WHAT IN THE WORLD Radio Netherlands' The Research File is an award -winning science and technology program now in its ninth year. The show, hosted by Anne Blair Gould, covers developments in space science, medicine, psychology, envi- ronmental research, science, and technology from Holland, across Europe and the world. Each week, Gould picks stories and answers to questions. What's interesting about this scientific development? What does it mean? And do these things really apply to us? Anyone interested in the "cutting edge" of science is bound to be intrigued. And its Futures segments reveal technological developments so new that they Anne Blair Gould, host of Radio Netherlands' science program, The Research File. haven't even happened yet! The Research File can be heard As with most assets of the former Tuesday: tourism or Slovakian per- during Radio Netherland's Monday Czechoslovakia, the existing short- sonalities. shortwave transmissions. This includes wave facilities were divided among Wednesday: business and eco- broadcasts beamed to North America new Slovakia and the Czech Republic. nomic news. during the 0030 and 0430 UTC sched- They consisted of a single 100 -kilowatt Thursday: domestic politics, sci- uled transmission periods. Frequenc- and two powerful 250 -kilowatt transmit- ence, and education. ies used during the former period are ters at Rimayska Soboto and Velke Friday: a cultural spotlight, includ- 6,020, 6,165, and 9,845 kHz; and at Kostolany within Slovakia. ing Slovakian cooking or language 6,165 and 9,590 kHz during the latter lessons. period. CREDITS: Brian Alexander, PA; Bruce Conti, NH; Robert Hill, MA; Harold Levison, PA; Ed Newbury, Saturday: a rebroadcast of the best Send both comments on the pro- NE; Benton Owsley, CA; George Poppin, CA; Ed feature segments of the week. grams and reception reports to Radio Rausch, NJ; World DX Club, c/o Richard Sunday: a mailbag program of lis- Netherlands, English Section, PO Box D'Angelo, 2216 Burkey Drive, Wyomissing PA teners' letters, and Slovakian music. 222, 1200 JG Hilversum, Holland. Or 19610; North American SW Association, 45 Wild- flower Road, Levittown PA 19067. Radio Slovakia International English send e-mail to letters @rnw.nl. 61

AmericanRadioHistory.Com PROGRAM GUIDE him as the head of EDXC is Risto much longer, so log it while you can. This month, I'm offering a taste of Vahakainu of Finland. The new This bit of Britain in the Far East is some of the most interesting program- address of the EDXC is P.O. Box 214, scheduled to revert to China and the ming available on shortwave radio. FIN -00101, Helsinki, Finland. Success BBC will remove its powerful SW trans- One source for information on SW and good luck to you, Risto! mitters. It is heard in mid -America programs, says Richard Cuff, writing in around 0950 UTC. his Easy Listening column in the DOWN THE DIAL MALAWI -3,380 kHz. MBC, the short- monthly Journal of the North American Here are some shortwave listening wave outlet of this southern African SW Association, is The International targets to try for. nation has been logged at 0248 UTC Directory of Shortwave Radio ALBANIA -7,270 kHz. Radio Tirana's sign on, with a rooster crowing interval Programs. The data is compiled by English programming probably isn't signal, and opening announcements. A John Figliozzi and, says Cuff, the quite as awful as it once was, but.... Still, strong signal suggests a more powerful book is available through RadioShack it does have some interesting Albanian transmitter. stores throughout North America." The music programming that's worthwhile. MEXICO -5,985 kHz. Radio Mexico price is $10.95. Try around 0345 UTC. International has a new English pro- BANGLADESH -9,548 kHz. Radio gram schedule. For an excellent seg- NEW GUY IN CHARGE Bangladesh has English until 1300 UTC ment of Mexican music, try tuning in Regular readers of this column sign off. Look for news, Bangladeshi from 0330 to 0400 UTC, Monday know of ANARC, the Association of music, and commentary before it leaves through Saturday. You can also find North Radio Clubs, the umbrella orga- the air. music at 1430 to 1500 UTC on 9,705 nization that provides links between BRAZIL -4,875 kHz. Radio Roraima kHz. the important radio listening clubs in has been heard on this frequency UNITED STATES -9,815 kHz. Radio the US and Canada. Promoting the around 0230 UTC with Portuguese -lan- Marti, America's Spanish language anti - hobby is an important function of guage programming, including popular Castro broadcaster, is beamed to Cuba ANARC. Not so well known to North music and commercials. by Voice of America transmitters at American listeners, though, is its coun- CZECH REPUBLIC -7,345 kHz. Radio Delano, CA. Listen around 0030 UTC terpart across the Atlantic, the Prague, an old familiar identification for Radio Marti identifications and a European DX Council. from the days before Czechoslovakia Spanish newscast. There is interfer- For the past 16 years, EDXC's sec- split into this republic and Slovakia, is ence from a Cuban "bubble machine" retary general has been Michael widely heard with English- language jammer. Murray of the United Kingdom. During programs at 0000 UTC and again at VENEZUELA -4,940 kHz. Radio that period, the organization has held 0100 UTC. You may also find it on Amazonas in Puerto Ayacucho was successful annual conferences and 5,930 kHz during the first half hour of heard in February on the station's first publicized the listening hobby at transmission, and on 6,200 kHz during day of operation. Reportedly it uses the telecommunications and electronic the latter period. former Radio Continental transmitter. exhibitions from London to Geneva. HONG KONG -7,180 kHz. British Listen for this one in Spanish during the In May, Murray stepped down from Broadcasting Corporation's Hong Kong evening hours until sign off, shortly after his longtime post. Elected to replace relay on shortwave won't be around too 0400 UTC.

ANTIQUE RADIO Boake Carter signature was inscribed Philco must have been used at night for (continued from page 60) on the dial or printed on it. That might long- distance listening because the call shed some light on whether the set letters displayed on it belonged to sta- mentators, with a rating of 12.6 by the was a one -of-a -kind model made for tions in Washington, DC; New York City, Crossley Survey, he is also far and Boake or part of a special limited -edi- Baltimore, and Philadelphia. Joe away the most daring. His freedom to tion promotional run. I'll let you know if Watkins (Boulder, CO) remembers lis- express any partisan opinion that pops there is more news on this. tening to Carter on either KSD or KMOX into his curly head is the wonder of a Thanks to the following readers for in St. Louis. W. R. Cobb (Laguna Hills, notoriously timid industry. However, writing or calling in and sharing their CA) is amused at my ignorance in not while Carter's crusty editorializing memories of Carter: Lloyd Zimmerman immediately recognizing Boake Carter's delights thousands of listeners, it cha- (Skokie, IL), Raymond F. Elsner name. He adds that it was not unusual grins thousands more, keeps him in a (Littleton, CO), Stan Niedermeier for Philco, during that era, to inscribe perpetual conversational stew." (Newport, MI), and William Barriger owner's names on radio dials which "He must have been the Limbaugh (Greenville, SC). Jim Ferris (Coos Bay, makes it plausible that the set might of his day," ventures Ron and draw- OR) believes that Paul Douglas, later a either have belonged to Boake or been ing on what I've since read about well -known actor, was the announcer signed by him personally.

Carter, I can vouch for the fact that for the Carter program. He remembers Thanks also to Alan Douglas such was indeed the case. Ron is listening to the show on a 1930 Philco (Pocasset, MA) and Tony Jacobi checking with set owner Shetrone to cathedral set. Thomas S. Ely, M.D. (Ralston, NE) for historical information 62 see if it can be determined whether the (Bloomfield, NY) noted that Shetrone's relating to Boake.

AmericanRadioHistory.Com SCANNER SCENE

Entering the Computer Age BY MARC SAXON

Thus far, we have not mentioned times 1000 characteristics. The com- great job. It can run on virtually any aspects of computer -aided scan- puter can do the job in about three DOS -based PC with at least 640 kilo- ning. You might not even be aware that minutes! You can also get CD -ROM bytes of RAM, and also runs as a DOS many high -end scanners come already databases showing FCC licensees. application under Windows or Windows equipped for computer control via a Scancat -Gold (Version 6.0) soft- 95. A Windows 95 version should be simple RS -232 serial port. ware offers computer control of major available by the time you read this. A The ability to control a scanner with brands of scanners, including AOR, fully operational demo disk is available a computer is similar to using a remote Icom, and RadioShack's PRO -2005/6 for $5, or you can request more infor- control to operate a TV-no more get- and PRO -2042 (with additional inter- mation, from Computer Aided Tech- ting up and down to change channels. face, not supplied), and others. The nologies, P.O. Box 18285, Shreveport, Many TV remotes are equipped with software restores cellular frequencies LA 71138. You can call them at 318- VCR Plus +, providing simple time -shift in the AR -800. With a simple menu 687 -2555, send e-mail to scancat@ recording by inputting a digital code. choice, you can select from several bcrr.secret.com, or check out their Web site at http: / /www.scancat.com.

READERS WRITE Seancat-GOLD Rick Montero, of Las Vegas, and Nevada, writes to mention that he Scancat 6.0 often sees Federal Express (FedEx) cargo aircraft in that company's TV commercials. He has also seen the planes at airports in Las Vegas, Los Angeles, and Dallas. Rick wonders if FedEx has a nationwide frequency for communicating with its fleet of aircraft. Co

there. I have monitored FedEx in that band on 131.925 MHz. But my own search efforts have also detected quite a bit of FedEx activity on 122.875 MHz. So it looks as if they are using Scancat -Gold software offers computer control of major brands of scanners, including AOR, (corn, and RadioShack's PRO -200516 and PRO -2042. It lets you scan between two frequencies, create and one of the two distant and inconspicu- scan disk files, search for new frequencies, log to files, and more. ous channels reserved for small cargo aircraft and commuter airlines. The Computer control of a scanner not radios to be used; scan between two other similar channel is 122.825 MHz. only provides "remote control," but frequencies; create and scan disk files, For the record, the United Parcel also unattended logging of everyth ng search for new frequencies, and log to Service (UPS) fleet of planes has been that is transmitted. Newer scanners files. With some radios, you can do monitored on 129.425 MHz, while the such as AOR's AR -8000 have 1000 spectrum analysis while you are scan- DL air cargo operations seem to occur programmable channels, each of ning and listening. The program has on 131.625 MHz. which can contain seven characteristic D -Base import ability and 15 scanning Here are some other aeronautical descriptions. Because the basic bands. With an added Optoelectronics tidbits. Pilots like to chat amongst "stand- alone" scanner enables input OS456 board, a PRO -2006 will also themselves while flying. Those conver- only by setting an individual adjust- decode PL and DCS codes. sations often range from raucous to ment for each characteristic, the scan - Scancat -Gold costs less than $100, raw. Regulations designate 122.75Mhz nist would have to program seven is easy to install and use, and does a continued on page 67 63

AmericanRadioHistory.Com 7E/IAA Yk09,g6

JOHN YACONO TECHNICAL EDITOR Jose Wins Again WINDOWS MAGAZINE

This month we'll showcase the increases; as current decreases the ated the field in the first place. work of Jose Ignatius A. Alea, magnetic -field strength decreases. This property can be useful, like for who has submitted another month's Well, a reciprocal rule holds, too: If you generating high voltages, or it can be worth of quality circuits. Before we get were to introduce a coil into a varying destructive, harming delicate compo- to them, however, I'll continue our dis- magnetic field, a potential would devel- nents if left unchecked. We'll explore cussion of inductors. op at its ends. some of the possibilities next month; Last time we discussed how the That brings us to an interesting but now, let's get to the letters. geometry of a coil helps concentrate property of inductors called "electro- the magnetic field generated by the magnetic kickback." Say we establish LIGHT-ACTIVATED current flowing within its turns. That a constant flow of current through an SWITCH configuration enables us to take inductor. Of course, a steady magnetic One evening while standing on the advantage of the relationship between field forms around and within the street, I was looking at the street lights electricity and magnetism, because it inductor. What happens if you discon- and thought it would be nice if I could makes it possible to generate signifi- nect the power supply? Well, current in make my outdoor lights switch on and cant magnetic fields with reasonable the inductor halts, but the magnetic off automatically. So I built the circuit in Fig. 1, which is simple and only requires parts available at RadioShack. When even a little light hits the light - dependent resistor, R5, transistor Q1 is turned off because the base has less resistance to ground than to the positive rail. In that situation, the base is at a negative potential. When the sun sets, R5 is no longer illuminated, giving the transistor's base a high resistance to ground- higher than 100,000 ohms. With less resistance to positive potential, the base is biased, turning on Q1. Relay RY1 is then energized and pulls in, connecting the SCR1's anode to positive potential. The 555 timer, IC1, powers up, and its output goes high to Fig. 1. This circuit will make your outdoor lights switch on and off automatically with the setting and rising of the sun. approximately 10.67 volts, which is sufficient to energize RY2. Relay RY2 then pulls in, keeping the AC bulb on levels of current. As experimenters, field doesn't simply vanish; there's a the whole night, and turning it off again the configuration also allows us to certain amount of energy invested in at sunrise. óexperience the relationship through the magnetic field and that cannot sim- Make sure the project is out in the simple experiments like last month's ply disappear. (The current helped open, say on a roof, so R5 will respond 11; electromagnet. generate and maintain the magnetic to even the slightest rays of the sun. The relationship between electricity field, but once started, the field is like a Cover the R5 with a transparent mate- magnetism, óand as we've explored it separate entity or force to be reckoned rial shaped like a converging meniscus eL thus far, is that "a steady current cre- with.) Instead the magnetic field lens, and glue the sides of the trans- rnates a steady magnetic field." What begins to collapse. That's analogous parent material to the enclosure, to sort of magnetic field does a varying to placing the coil in a varying magnet- protect the light- dependent resistor ócurrent produce? Well, the magnetic - ic field. The result is a very high volt- from rain. A 12 -volt power supply com- 8 field strength is proportional to the cur- age generated at the leads of the pletes the circuit. rent, so a varying current creates a coil -the kickback -which if connect- -Jose Ignatius A. Alea, Cebu, varying magnetic field. As current ed to a load, would generate current Philippines 64 increases, the magnetic -field strength that would oppose the current that cre- Interesting use of the 555. Since it's

AmericanRadioHistory.Com an outdoor project, I'd seal the case ing the relay. Releasing S1 places the turning off the SCR. Or you can press with silicon caulk. Also be sure not to circuit back in standby mode. S1 to turn the circuitry off. work on the circuit while it's connected The light- dependent resistor, R2, is -Jose Ignatius A. Alea, Cebu, to AC. used if you want to turn on the circuit Philippines via infrared. Just make sure to cover Exposed Kodachrome film works TOUCH /INFRARED R2 with an IR filter, to protect it from great as an IR filter. The remote con- SWITCHES unwanted light rays, which result in trol can be made from a normally open This touch switch (see Fig. 2A) con- false triggering. pushbutton, a resistor, a high- intensity trols an AC- powered bulb, and Using a battery as a supply is not IR LED, and a battery-all in series. A requires only a few parts. Touching the advisable. As the battery's energy simple flashlight with an IR filter will touch plate triggers the SCR's gate, decreases, the touch switch would no also work. Either way, I'd use a lens to turning it on and allowing current to longer function. Use a 9 -volt regulated make the range practical. flow from the cathode to the anode of power supply instead. SCR1, thereby activating the relay. The circuit in Fig. 2B operates in ALTERNATE TOUCH SWITCHES John, this switching device (see Fig. 3A) can be used for AC- switching or any other application whenever a switching device is needed. It is built around an oscillator /timer IC configured in a way that makes it function as a one -shot monostable device. When S1 is closed, the circuitry is on in standby mode. When the touch plate is touched, the output of 555 -timer IC1 goes high, supplying a positive potential to the base of transistor Q2, aiding its bias. The transistor is then on, allowing current to flow through pins 4, 5, and 6 of 102. The gate of the SCR is then triggered, the relay is energized, and its contacts turn the AC bulb on. To turn the bulb off, just press S2 (reset), which disconnects the anode of the SCR from the positive supply, turning it off, and de- energizing the relay. The light- dependent resistor (R7) is used if you want to turn on the circuit remotely. Just point a flashlight at R7 to decrease its resistance, therefore leaving only the 1,000 -ohm resistor as the base resistance. That resistance gives the base a positive potential, forward biasing the emitter -base junction of transistor Q1. Transistor Q2 is also B turned on, as its base is made positive by Q1, which triggers SCR1, energiz- Fig. 2. Turn on an AC bulb by touch or with IR light using this circuit (A). Another circuit (B) lets ing the relay. switch. you also turn off the bulb by touch or a pushbutton Just be sure that R7's sensing portion is covered with an infrared filter; When that happens, the relay's con- the same way, but it is equipped with a you can use a developed color film for tacts pull in and turn on the bulb or light- dependent- resistor switch for that. Use a flashlight with an adjustable whatever you connect to the circuit. turning the circuit off. When R5 is illu- beam lens, so the light rays are nar- Just be sure that the relay contacts minated by a flashlight, its resistance rower and more concentrated at the can withstand the high-voltage AC To lowers, leaving only 10,000 ohms as center. The touch plate is very sensi- turn off the circuit, just press S1 (a nor- the minimum base resistance. That tive, so be sure to install it on a plastic mally closed pushbutton switch) to dis- process gives a positive potential to material to prevent unwanted trigger- connect the anode of the SCR from the base of Q1, therefore turning on ing. The touch plate can be made of the positive supply, thereby de- activat- the transistor, activating RY2, and any electrical conductor. 65

AmericanRadioHistory.Com Ovo +12V energizing RY2. When the contact of D2 S1 R4 RY2 pulls in, it disconnects the anode 50052 1N4001 of the SCR from the positive supply, Ar TO 117 VAC therefore turning it off. Or you can R1 press 52 to energize RY2 and turn off 1K S2 the AC bulb. -Jose Ignatius A. Alea, Cebu, Philippines 2 AC Jose also advises us to use either IC1' IC2 SCR1 BULB an NE555P or NE555N, as not all 556 4N35 2N5060 555s will work as touch -activated monostables. If you wish to experi- Cl ment with various 555s, say from your VC R2 .47 junk box, then use a socket to accom- 2.2K RY1 12V modate the IC. R5 220K D1 1N4001 LIGHT FLASHER in TOUCH R8 02' The circuit Fig. 4 is an AC light 3300 PLATE ECG123AP flasher. It's built around a 555 oscilla- 'SEE TEXT tor /timer IC in an unusual configura- A tion. Pins 5 and 6 are shorted together, so that both comparators in the 555 will have the same potential, VV keeping R5 D3 the output low. If both are disconnect- R4 6800 1N4001 1000 ed, output -pin 3 always goes high. With both pins shorted, the 555 uses S1 q only its other comparator to turn the output high and low. R9 R7 +12V 1K 1000100 When there is no light detected by --4/4/4r- light- dependent resistor R1, pin 2 is at 2 negative potential because the resis-

IC1 IC2 tance of R1 plus R4 is higher than 555 4N35 02 100,000 ohms. The 555 (IC1) is thus = 1N4001 triggered, thereby driving pin 3 high, o-I-À and energizing the relay at the same Cl R11 .47 R6 RY2 100 time. The contacts pull in, turning on the 2.2K 6V lamp. When R1 senses the light, it pulls R2 pin 2 positive through R4, bringing ICI's R14 1M. 220K R10 output low, and de- energizing the relay. 4700 The R8 a2 output of IC1 is approximately T TOUCH SCR1 3300 9.57 volts and its current is 20 mA in a N PLATE ECG123AP 2N5060 03 ECG128P 12- volt/500 -mA R12 circuit, which is suffi- 220K cient to drive the relay. The 270 -ohm -14/V- S2 resistor acts as a current -limiter for 0 Li AC o RY1 D1 R13 ICI. TO 117 VAC BULB 12V = 1N4001 33052 The light- dependent resistor will suf- I 'SEE TEXT fer memory effect if exposed directly to B sunlight. If possible, use an IR filter if Fig. 3. This alternate touch- and light -controlled switch is built around a 4N35 optocoupler (A). A you use the circuit in direct sunlight. variation (B) allows for remote shut -off of the circuit, using a strong flashlight. -Jose Ignatius A. Alea, Cebu, Philippines The switching device in Fig. 3B is SCR's gate and energizing RY1. With Running the power supply off the similar to the one in Fig. 3A, but more RY1 energized, its contacts pull in, AC line seems natural enough, so convenient because it has a remote off turning on the AC bulb. When R1 is hit bring both lines into the project box and switch. When the touch plate is by strong light, it turns on the SCR and run two wires to the AC load, rather touched, it turns the output of IC1 on, energizes RY1. To turn the AC bulb off, than placing the project in series with giving a positive potential to the base just point a strong flashlight at R2, the load and AC source. of 02. In turn, that turns on pins 4, 5, decreasing the base resistance of Q3, Be sure to insulate all the AC con- 66 and 6 of IC2, therefore triggering the making its base positive, and therefore nections thoroughly.

AmericanRadioHistory.Com You car see from Fig. 5 it's built around a 4N35 optocoupler. When the +12V test leads are shorted by a resistance, it turns IC1 on by pulling pins 2 and 4 low, allowing current to flow through To 117 VAC R3 pins 6 and 5. Current to pin 5 flows 220K AC through either the buzzer or the LED, BULB depending upon the position of Si. To test continuity of 50 ohms or less, use the buzzer as the indicator. For continuity of up to 1000 ohms, use the LED. The circuit can also be used to check PN junctions of transistors and Fig. 4. This AC light flasher is built around a 555 oscillator/timer IC that is configured rn an 10114,S11- less possibility of damag- al way. diodes, with ing such sensitive components. For the LED, and connect the CONTINUITY CHECKER er, but I was determined to design one that, use John, while working on some elec- that is smaller and more handy. So I lead from pin 2 of IC1 to the P side. it The can be from 7.5 to 9 volts. tronic equipment, I came to the point threw some parts together and supply

I it it's Ignatius A. Alea, Cebu, when I wanted to make a continuity worked just as wanted to; useful -Jose test. My DMM is equipped with a check- and fits comfortably into my pocket. Philippines To catch fast pulses, folks might want to trigger a monostable with pin R1 5, and use it to drive the LED and the 47052 BZ1 R2 3V buzzer. The monostable will act like a 56052 6 pulse stretcher. ---MVr- ICi and gone. +utas R4 Another column's come 10052 Remember, if you've got some interesting circuits for me, send them to TEST Vi R3 `./ Think Tank, Popular Electronics, 500 LEADS + cl LEDI 1552 B1 ^ 100 Bi- County Blvd., Farmingdale, NY o-0 I 9V 1+ 11735. If they appear here, you'll receive a book from our library. Send Fig. 5. Switch Si in this continuity checker lets you decide whether you want an audible or visible enough to fill a whole column, and indication of continuity. you'll get a kit and MCL1010 chip,

prosecuted. While scanners can't actu- descending. First he entered the fre- SCANNER SCENE ally track a specific channel sequence, quencies in descending order, five (continued from page 63) they can monitor system groups. times. The radio then only scanned that as the yak channel for private fixed - Most systems use groups of five fre- bank of 20 frequencies. When the scan- wing aircraft, and 123.025 MHz for quencies, or multiples of five, taking the ner stopped because of a transmission, choppers. Sometimes private pilots total number up to 20 or 25. Each group he pressed MANUAL to kill the scanning also chat on 122.9 MHz, and airline of five will have the same kHz exten- action. When he heard the tone, he pilots have unofficially appropriated sion, for example, XXX.0125 could press MANUAL and there they 123.45 MHz for exchanging chit chat. (851.0125, 852.0125, 853.0125 MHz, were! The drawback was that if the fire Within the past year, several additional, etc.). Many of those systems change department was on the next channel, totally unauthorized pilot -to -pilot chan- frequencies in descending frequency he had to press MANUAL again. That nels have been reported. by our read- order; consider that when programming method worked fine until the system ers. They are 122.775, 122.85, a scanner. began randomizing the data channel 122.925, 126.125, and 136.975 MHz. One way to approach the situation every hour. One observer notes that would be to monitor late at night, prefer- this concept won't work with any of the WHAT'S IN THE TRUNK? ably on a week night, when the traffic is Uniden models that will scan only in a In response to many inquiries, there light. It's easier then to follow how that ascending frequency order within isn't any (legally) available software to particular trunking system is shifting given bank, regardless of channel permit standard scanners to follow 800 - from channel to channel. assignment. Such is life. MHz trunked communications systems. A scanner owner reports that he had If you can offer insight into scanning There are several different types of been able to track his local police and trunked systems, or just want to keep in trunking systems in use, but the soft- fire departments' trunked repeater sys- touch, write to Scanner Scene, Popular ware that controls frequency movement tem by knowing the order of frequen- Electronics, 500 Bi- County Blvd., is copyrighted and pirates have been cies the repeater worked, which was Farmingdale, NY 11735. 67

AmericanRadioHistory.Com CIRCUiT CIRCUS

Op -Amp Applications BY CHARLES D. RAKES

ately it seems like more questions are being asked about op- N 0 +9-12V amps than any other active electronic D1 1N4002 component. How do they work? What C.T. c1 I+ 5000 can they do for me? How do I hook D2 1N4002 them up? Those are all common 1 queries hobbyists make and, this T1' month, we'll try to address a i few of D3 those concerns. 1N4002 C2 + When the first integrated- circuit 'SEE TEXT 5000 operational amplifier hit the market, it D4 1N4002 gave the world a magic analog device T O 9-12V that changed electronics forever. The generic op -amp is a two- input, differ- Fig. 2. Here's a simple dual - voltage power- supply that can he used to power the op -amp circuits in this month's column. ential, high -gain DC amplifier. Being very versatile, op -amps are used in AC and DC amplifiers, active filters, com- CMOS- INTERFACE PARTS LIST FOR THE parators, integration and summing cir- DRIVER DUAL -VOLTAGE SUPPLY cuits, and in many other analog circuit Our first op -amp circuit application, (Fig. 2) functions. see Fig. 1, places IC1, a general -pur- D1- D4- 1N4002 silicon rectifier diode pose LM741 op -amp, in an interface - Cl. C2- 5000 -µF, 25 -WVDC, electrolytic TO driver circuit for operating with CMOS capacitor TO CMOS T1 -117- to 12 -volt center -tap trans- +9v digital circuitry. The op -amp is con- INPUT CIRCUITRY former (see text) nected in a comparator circuit with its Sl -SPST switch R2 output tailored to safely connect to the F1 -0.5- ampere 4.7K fuse Wire, solder, etc. R1 6 input of a CMOS integrated circuit. 10K Ic1 * Diode D1 clamps any negative voltage 4 LM741 D1 that could damage the CMOS device. DUAL -VOLTAGE SUPPLY TO REFERENCE 1 N914 When ICI's input voltage goes Our next entry, in VOLTAGE -9V shown Fig. 2, is a below the reference voltage at pin 3, simple dual -voltage 'SEE TEXT power -supply cir- the output at pin 6 goes high; when the cuit that can be used with our op -amp Fig. I. This CMOS interface makes it possible input voltage goes above the refer- circuits. Transformer T1 can be any for a simple or complex analog circuit to input ence voltage, the output goes low. data into a digital system. The low -cost, low- current, 12 -volt, center - low or negative clamped output of IC1 tap unit you have kicking around in PARTS LIST FOR THE pulls the CMOS input low for a "0" logic your parts box, or one purchased from CMOS- INTERFACE DRIVER input. When ICI's output is high, a "1" a local parts house. In any case, the (Fig. 1) logic output is then fed to the CMOS output current isn't critical and can be

ICI -LM741 op -amp, integrated circuit device. anything from 50 mA to 1 A. The filter D1-1N914 silicon diode The main advantage of the CMOS capacitors, Cl and C2, should be as R1- 10,000 -ohm, i;4 -watt, 5% resistor interface is that it makes it possible for large in value as possible for a clean, R2 -4700 -ohm, 1:4 -watt. 5% resistor Wire, solder. etc. a simple or complex analog circuit to ripple -free output. input data into a digital system. A good example of its use would be with an AC AMPLIFIER An ideal op -amp would have infinite analog sensor that has a slow-chang- The circuit shown in Fig. 3 takes a open loop gain and input impedance, ing output. The sensor might not nec- not -so- well -known type of op -amp and as well as an output impedance of essarily produce a good input signal places it in an AC amplifier circuit with zero. In the real world of op -amps, for digital processing, but when the a pre -set gain of 50. The LM3900 however, those characteristics don't sensor's output is fed through the op- Norton or current -difference amplifier exist and probably never will. The amp the output level changes very (IC1) really isn't a true op -amp at all, available op -amps are still very useful, fast, which produces a good logic input but does simulate an op -amp in its per- 68 though. to the CMOS circuitry. formance. One important feature that

AmericanRadioHistory.Com changed, be sure to adjust R3 accord- +9V ingly. TO INPUT +9V +9V R1 1 ADJUSTABLE w2.2K COMPARATOR IC1 R3 LM741 4I Our next circuit, see Fig. 4, contains 100K an LM741 op -amp in an adjustable -9V LED1 comparator configuration, with an LED O\ +9V Q LED2 +9V Fig. 3. While the LM3900 current- difference R2 amplifier (ICI) used in this AC amplifier really 2.2K 6 isn't a true op -amp, it does simulate one in its performance: however, the IC requires only a 1C2 LM741 one- polarity power source. 4 100K PARTS LIST FOR THE -9V LED3 Q AC AMPLIFIER (Fig. 3) LED4 \4\4 RESISTORS (All resistors are 1,4 -watt, 5% units.) R1- 20,000 -ohm R2-1 -megohm to monitor a R3- 2.2- megohm Fig. 5. Use this dual comparator Fig. 4. This adjustable comparator may he used battery while it's charging: the circuit will let to drive devices such as an optocoupler con- condi- ADDITIONAL PARTS AND you check for under- and over -voltage trolling an AC circuit, or a transistor- driven MATERIALS tions. relay. IC1- LM3900 quad op-amp, integrated circuit PARTS LIST FOR THE ¡ PARTS LIST FOR THE Cl , C2-- 0.1 -µF, ceramic -disc capaci -or DUAL - VOLTAGE Wire, solder, etc. ADJUSTABLE COMPARATOR COMPARATOR (Fig. 4) (Fig. 5) op -amp, int the LM3900 offers is that it requires IC1-LM741 1C1, lC2 -1.M741 op -amp, integrated LED1, Light -emitting diode, any only a one -polarity power source (that LED2- circuit color is, one power pin connects to a positive LED1-LED4- Light -emitting diode, any R1 -2200 -ohm, 1,4 -watt, 5% resistor color and the other connects to potentiometer supply R2- 100,000 -ohm R1, R2- 2200 -ohm, 1,4-watt, 5% resistor etc. ground). Wire, solder, R3, R4- 100,000 -ohm potentiometer

The amplifier's gain is set by select- Wire, solder, etc . ing the values of R1 and R2 as in a indicator. With R2 set for a positive 1- standard op -amp circuit. Gain is equal volt level at pin 2, and the input voltage use for this dual comparator would be to at pin 3 below 1 -volt, the output will be to monitor a battery under charge to negative, turning on LED1. When the check for under- and over -voltage con-

R2 / R1 voltage level at the input goes above ditions.

the 1 -volt level, the output switches Also in this circuit, the LEDs may be The IC's positive input current at pin 2 positive, turning LED2 on and LED1 replaced with other devices to control is set by selecting the value of resistor off. external circuitry. An optocoupler R3. The op -amp's output at pin 6 may could be used in a battery- charging The current at pin 2 should be the be used to drive other devices such as circuit to shut the charger down in same as the feedback current for the an optocoupler controlling an AC cir- case of an over -voltage charge condi- input at pin 3. The voltage at the out- cuit or a transistor -driven relay. Another tion. put is about half of the supply voltage, option is to use this comparator in a or in this case 4.5 -volts DC. Because similar fashion as the circuit in Fig. 1- FOUR -LEVEL the current source for the positive that is, to couple an analog circuit to VOLTAGE DETECTOR input is taken from the full supply volt- the "digital world." In the circuit shown in Fig. 6, an age, the resistor value would be about LM339 quad comparator, IC1, oper- twice the size of the feedback resistor, DUAL -VOLTAGE ates as a four -level voltage detector. R2. The nearest available value is 2.2 COMPARATOR Four 100,000 -ohm potentiometers, megohms. The circuit in Fig. 5 contains two 741 R5 -R8, allow for individual voltage set- The AC gain may be varied by op -amps (IC1 and IC2) in a dual -volt- tings for each section of the compara- changing the R2 /R1 ratio. A 10,000 - age comparator circuit. Potentiometer tor. To provide status indication, four ohm resistor used for R1 increases the R3 may be adjusted for one input -volt- LEDs are connected to the output of amplifier's gain from 50 to 100. If R2 is age level and R4 for another level. One the comparator sections. 69

AmericanRadioHistory.Com VCR

Cross Reference +9-12V

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11 R4 2.2K 13 10 TO IC1-d LEDO +DC 12 1/4 LM339 With the INPUT MEET VCR Fig. 6. This four -level voltage detector can be used as a bargraph voltmeter. Simply set each poten- CROSS REFERENCE tiometer (RS -R8) for a specific voltage. This 119 -page reference contains both model and part- number cross - references updated to include 1994 A SaLVST FOR ThE +9 -16V units. FOUR -LEVEL VOLTAGE VCR's are made in a few factories DETECTOR (Fig. 6) from which hundreds of different IC1 -LM339 quad comparator, brand names and model numbers integrated circuit identify cosmetically- changed iden- LED1 -LED4- Light- emitting diode, any tical and near -identical manufactured color units. Interchangeable parts are very R1 -R4- 2200 -ohm, 14-watt, 5% resistor common. An exact replacement part R5 -R8- 100,000 -ohm potentiometer `C1- 0.1 -pF, ceramic -disc may be available only a few minutes Wire, solder, etc. away from you even though the manufacturer supplier is out -of- stock. The circuit may be used as a bar - You may be able to cannibalize scrap graph voltmeter with each potentiome- units at no cost! ter set for a specific voltage. If you build The ISCET VCR Cross Reference two of the quad comparator circuits and is pre -punched for standard loose - connect the inputs together, you can Fig. 7. Using a leaf binding. . .$38.00 plus $3.00 for digital voltmeter, set the reference shipping for each Reference. create a voltmeter with double the read- voltages in this voltage window to the same val- out resolution. ues. Then vary one to set the width of the win- Claggk Inc. dow; when the input voltage is within the window area, LEDI VCR CROSS REFERENCE OFFER VOLTAGE WINDOW will light. P.O. Box 4099 Farmingdale, New York 11735 -0793 Our last entry, see Fig. 7, uses two PARTS LIST FOR THE Name sections of a quad LM339 comparator VOLTAGE WINDOW (Fig. 7) in a voltage- Business window circuit. The positive IC1 -LM339 quad comparato ' Address input of one comparator and the nega- integrated circuit LED1- Light- emitting diode, City tive input of the other are tied together any color` -- R1. R2- 10,000 -ohm ten -turn State Zip and serve as the input circuit. The potentiometer Phone remaining two inputs are connected to R3- 2200 -ohm, 1'4 -watt. 5% resistor Enclose $38.00 for the Fifth Edition of the ISCET two ten -turn potentiometers, R1 and Wire, solder, etc. VCR Cross Reference and $3.00 for shipping for each Reference. R2. The comparator's outputs, which The total amount of my order is $ Check enclosed-do not send cash. are both tied together, operate LED1. will light. The circuit is very sensitive, or please charge my credit card. The easiest way to set the window allowing the window opening to be set Visa MasterCard Exp. Date /_/ circuit up is Card No. to use a digital voltmeter to only a few millivolts, or, if you prefer, Signature and set the reference voltages to the wide open for several volts. New York State residents must add applicable local same voltage, and then vary one to set Now that we've looked at six simple sales tax to total. US funds only. Use US bank check or International Money Order. CB02 the width of the window. When the input op -amp circuits, see if one can find a 70 L voltage is within the window area, LED1 place in one of your projects.

AmericanRadioHistory.Com ive a Frienc1 á Year of IH1ectronics

Fun this Christmas .

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AmericanRadioHistory.Com COMPUTER BiTs Help Tools BY JEFF HOLTZMAN

Last month we talked about the topic. Both the help system and the insert the Topic ID of the topic to which hypertext, and particularly about help author use the Topic ID as the tar- you want to jump. Then you format the how to create Windows help files from get of a hypertext jump. Topic ID as hidden text.

scratch. This time, I want to take a The dollar sign specifies the title of If that process sounds convoluted, brief look at three tools that help auto- the topic. The title is what the help sys- complicated, unintuitive, and so on -it mate help -file creation. tem displays as the result of an end - is. But that's what help authors have

Incidentally, I should point out that a user search or find operation. The been struggling with for years. So now help file doesn't necessarily have to be Topic ID and the title may be identical. let's look at the tools and see how they a help file. You can publish any text Neither is required, and there are legit- can help. and graphics in a help file. Some peo- imate reasons for excluding them. ple create on -line résumés. Some Normally, however, both are used. THE TOOLS companies use WinHelp to publish Capital K is the third footnote code. RoboHelp is published by Blue Sky corporate information. Others use it for It allows the help author to specify key- Software and sells for $599. It is a cod- on -line catalogs. The nice thing about words by which the help file may be ing automator. That is, it helps auto- help files is that you have a guaran- searched. The list of words you see mate the process of inserting footnote teed compatible audience of every under the Index tab of the Win95 help codes, underlining, hidden text, and all Windows desktop on the planet. The system is simply a sorted list of all the the others. The software thoroughly Web and browser technology is cutting words specified in all the K footnotes in integrates itself into Microsoft Word, in to that type of use, but it's still viable all the topics of all the help files in the which is required to run the program. as a publishing medium. help system. K keywords are equiva- The RoboHelp helps you keep track of Many tools, both shareware and lent to index entries in a print manual. Topic IDs (jump targets), but only by commercial, are available for helping Then there are the two kinds of for- means of lists, not graphically. to create help files. All of them fall into matting: underline and hidden text. Doc -To -Help 2.0 by Wextech one of three categories: coding You underline a word or phrase (or Systems goes for $395. It also inte- helpers, WYSIWYG designers, and graphic) that you want to use as a hot grates itself thoroughly with MS Word. document converters spot. Immediately following it, you However, it attempts to shield the help I'll talk about one example from each: RoboHelp, The Hypertext Suite, and Doc -To -Help. But first let's talk about some of the coding that is required to build a help file. # $ K + > C/C ++ Elements When creating a Windows help file, you have to be concerned with two Index Link kinds of text formatting and three foot- ClassesCiasses note codes. (There are other coding Index Link MethodsMethods styles and footnote codes, but these Index Link FunctionsFunctions are the most commonly used.) The two types of formatting are hidden text and All Footnotes underlining. The footnote codes are the pound sign, the dollar sign, and Normal capital K. + Contents:0000 In a help file, the unit of information T Footnote ext # C.C..Elements is a topic. A topic may be one screen Footnote T ext full of information, or more information, $ C /C ++ Elements in which case, scroll bars appear. In Footnote Text K C /C ++ Elements: the source code for a help file, a hard Footnote T ext page break separates topics. Typically + SECTION:0280 following the page break is a topic title, such as "C /C ++ Elements." The foot- Creating Windows help files is a lot like programming in assembly language. There are lots of down - note codes precede the title. and -dirty details that make it hard to focus on more important details -like helping your users get 72 The pound sign specifies the ID of help!

AmericanRadioHistory.Com author from the nitty gritty details by RH is also much speedier than D2H. VENDOR INFORMATION having the author work in what is HWA makes an admirable stab at sur- essentially a paper -based paradigm. In Blue Sky Software passing the WinHelp coding paradigm. 7777 Fay Ave., Suite 201 Its limitations are weak paper- document other words, you write as if for a paper La Jolla, CA 92037 manual. Then you run a conversion support, slow performance, and user - process, in which D2H creates sepa- HyperAct Inc. interface quirks. 3437 335th Street rate RTF files with all the appropriate Ironically enough, all three products West Des Moines, IA 50266 coding. The downside is that the con- are poorly documented. But any of them version process is slower by orders of Wextech Systems is better than working with just Word (or magnitude than the help compiler. For 310 Madison Avenue, Suite 905 God forbid, raw RTF files) and the help New York, NY 10017 example, in one project I recently over- compiler. saw, the D2H conversion took about 20 It's also worth noting that both RH minutes, while the help compiler took the Help Writer's Assistant, HWA, is the and HWA have export-to -HTML options, about 8 seconds. help- authoring tool. The suite also which allows fairly straightforward con- HyperAct Inc, delivers The Hyper- includes a scripting language that adds version of help- system documents to text Suite which includes the Help a degree of interactivity to WinHelp files. Web- browser format. However, don't Writer's Assistant 2.1 Professional for HWA is available separately at lower get your hopes up too high; the conver- $375. If all you need is the Help Writer's cost, and is downloadable shareware. sion is not exactly foolproof. Assistant, it costs $199. The system dis- Doc -To -Help is the easiest way to There is a small but active interna- penses with Word and the paper -based create a help file. It also allows you to tional community of Windows help paradigm altogether. Instead, HTS goes concern yourself with higher -level developers on the Internet. You can get for a WYSIWYG authoring environ- issues than document formatting. But more information in the Help section of ment, in which a multi -pane window lets on a project of any size, it is slow. the Windows SDK forum on you view your hypertext structure as an RoboHelp depends on a much deeper CompuServe (Go WINSDK). There are outline, and individual topics in a word - understanding of WinHelp coding con- also news net and mailing list groups on processing pane. Actually, HTS conventions, but provides much more pre- the Internet that serve the WinHelp sists of several components, of w'7ich cise control over the finished product. community.

Models 2005 and 2015 digital stainless -steel thermistor probe. NEW PRODUCTS multimeters cost $159.95 and $179.95, Model 392050 has a two -inch diame- (continued frone pu e 29) respectively. For more information, con- ter, round dial head with a 0.4 -inch multimeters each come with a prctec- tact Wavetek Corporation, Instruments LCD readout. Model 392065 has a T- tive holster, operator's manual, test Division, 9045 Balboa Avenue, San bar head with a 0.19 -inch LCD. Both leads, battery, and extra fuse. The test Diego, CA 92123; Tel. 619 -279 -2200; come with a plastic protective sheath leads are over-shrouded to eliminate Fax: 619- 565-9558. with a pocket clip, and a 1.5 -volt button the possibility of shock in dense mea- CIRCLE 76 ON FREE battery. INFORMATION CARD The Models 392050 and 392065 stem thermometers each cost $25. For STEM THERMOMETERS additional information, contact Extech Two stem thermometers from Extech Instruments Corporation, 335 Bear Hill are designed for use in liquids and Road, Waltham, MA 02154; Tel. 617- semi -solids. Both can be switched 890 -7440; Fax: 617 -890 -7864; e-mail: between Celsius and Fahrenheit and extech @extech.com; Web site: http: // www.extech.com. CIRCLE 77 ON FREE INFORMATION CARD

SOLDERING IRONS Antex soldering irons from M.M. Newman Corporation heat up rapidly, provide quick recovery times, and are comfortable to hold because their heating elements are located directly under the tips. The soldering irons accommo- offer high resolution of 0.1° to 199.9° date a wide variety of slide -on tips for suring areas. A warning beeper and 1° over 200 °. They are accurate to specialized applications.

sounds when the test leads are placed less than 2 °F and 1 °C. Placing the heating element under incorrectly. Both models feature a five -inch continued on page 75 73

AmericanRadioHistory.Com HAM Radio

The Folded Dipole BY JOSEPH J. CARR, K4IPV

Antennas are one of my pas- The feedpoint is formed by break- amounts of RF power in transmitting sions. Many of the antennas ing one of the two conductors at its stations, and in all receiving stations,

that I have covered in these pages and midpoint. The feedpoint impedance of but one has to be a bit careful as

elsewhere have been a bit esoteric. this antenna is just under 300 ohms, power levels increase. I recall one 40- And although they all provide some so it makes a good match to another meter folded dipole fed with around advantages to the builder and user, piece of 300 -ohm twin -lead used as a 400 watts of RF that got uncomfortably they are not always simple to build and transmission line. hot to the touch after just a few min-

erect. From time to time, I like to cover The overall length of the folded utes of CW operation. one of the fundamental antennas. dipole is found from the same equation Folded dipole construction always looks easier in magazine articles than it is in real life. The problem is that the

A conductors used in 300 -ohm twin -lead are small, and not intended to support B k B any weight or stand up under wind ü>: O forces (that can be larger than most of us imagine because the antenna has a large "sail area" in wind). As a result, folded dipoles usually break and come 4:1 down either at the feedpoint or one of BALUN 75-OHM the two ends. The solution is to make COAX fittings such as the ones shown in Fig. 2 for the center and Fig. 3 for the ends. The folded dipole fittings in Fig. 2 must be made from an insulating mate- Fig. 1. The basic folded dipole. The letters are used in the formula to determine length of the element for specific frequencies. Note the holes for mounting the antenna on an insulated support. rial. I've seen similar devices made of hardwood salvaged from flooring, and then coated in polyurethane or varnish

In the past several months I have as a regular half wavelength dipole: to protect against rain. Others use received several questions about fold- Plexiglas, Lexan(, or other materials. ed- dipole antennas in my e-mail box. L = 468/f I've even seen one commercial folded - One was of the "what are these things" dipole center insulator made of high - variety, but others dealt with the practi- where L is the length in feet and f is the impact nylon, but it seems to have cal aspects of actually building a fold- frequency in MHz. disappeared from the marketplace. In ed dipole. Building folded dipoles is There may be a small amount of Fig. 2, the wire connections are sol- not all that hard, but building one that additional foreshortening due to the dered to solder lugs attached to brass stays up can be more than a little prob- velocity factor of the twin -lead, so this machine screws. All other screws and lematical. length may be a bit long for the desired The half-wave folded dipole anten- frequency. You can adjust to the na (see Fig. 1) has a wider bandwidth desired frequency by trimming the than the common half -wave dipole. same amount off each end while mon- But the improved bandwidth comes at itoring the VSWR to determine the res- the expense of more complex con- onant frequency. struction. The folded dipole consists of If you want to use coaxial cable to a loop of wire made from a half -wave feed the folded dipole, insert a 4:1 section of twin -lead or parallel trans- balun transformer at the feedpoint. It mission line. The most common form reduces the feedpoint impedance from of folded dipole uses 300 -ohm televi- near 300 ohms to near 75 ohms to sion antenna twin -lead for the radiator make a good match to 75 -ohm coaxial element. Note that the two conductors cable (e.g. RG -59 or RG -11). of the twin -lead are shorted together at A folded dipole made of 300 -ohm Fig. 2. Here's a detailed look at a home -brew center insulator. 74 both ends of the radiator. twin -lead can be used with moderate

AmericanRadioHistory.Com CLAMPING FIXTURE TWIN -LEAD CHAIN END SUPPORT LINK INSULATOR ROPE

Fig. 3. An end insulator for a twin -lead dipole is easy to make if you follow this diagram. nuts are made of nylon to minimize connection you'll become a big smok- Street, Newington, CT 06111. Some interaction with the antenna. ing hole in the ground. Mixing anten- people feel a little antipathy for the

Note in Figs. 1 through 3 that holes nas and AC power lines is a lethal ARRL, for real or imagined grievances, are cut into the insulation of the twin - stupidity. but there is one thing that is for certain: lead, and nylon machine screws are with regard to WARC -99 they are basi- passed through both these holes and WARC -99 WARNING cally the only game in town. mating holes cut into the mounting Every ten to twenty years the I can be reached by snail mail at P.O. device. Matching hex nuts on the other nations of the world convene in Box 1099, Falls Church, VA, 22041, or side secure the screw (see side view Geneva, Switzerland to haggle about by e-mail at carrjj @aol.com. in Fig. 4). This keeps the twin -lead the allocation of the radio -frequency from slipping out of the block, or at spectrum. This is called the World NEW PRODUCTS least delays the day when it might fail. Administrative Radio Conference (continued f=oni page 73) The preparation of the twin -lead is (WARC), and since the next one is in shown in Fig. 4. Cut the length of he 1999, it is being called WARC -99. It the tips provides optimum thermal effi- twin -lead radiator element according was during WARC -79 that ham opera- ciency. The Antex line includes the to the equation mentioned earlier to tors won the use of the 30- meter, 17- G /3U 18 -watt miniature iron, which match the intended frequency for the meter, and 13 -meter bands. But that heats up to 750 °F; the standard Model antenna. At the exact mid -point of the doesn't mean we will win anything the XS 25 -watt iron, which reaches 800 °F; twin -lead, cut one of the conductors next time. Indeed, there is a strong and the temperature -controlled Model and strip it back a bit on both sides. danger that we will lose spectrum TCS, whose in- handle controls allow This is the feedpoint for the antenna's space. the temperature to be adjusted from transmission line. Also strip the wires at both ends of the dipole so the two conductors of the FILL Ida... twin -lead can be connected together . (the folded dipole forms a complete s. MNWINil 111 loop with a very low -near zero- resistance at DC, (but not at RF). Cut the holes in the twin -lead with a paper Fig. 4. This side view of the center insulator hole punch. Alternatively, you can use shows how it protects the twin -lead antenna a leather hole punch. wire. Solder all connections with either 50/50 or 60/40 resin core solder The financial value of spectrum (never use acid core solder in elec- space has never been greater because 390 °F to 850 °F with ± 1% stability dur- tronics!). You are not soldering to proof the proliferation of wireless technolo- ing use. All three models are ready to vide strength, but rather to protect the gies. One package -delivery service solder in just 45 seconds. The light- electrical integrity of the joint. has already attacked the 220 -MHz weight soldering irons feature plastic ham band, and that's only the start. handles that stay cool, making work SAFETY WARNING Look for attempts to take over many of more comfortable. Erecting antennas can be danger- our bands, especially in the VHF, UHF, Prices for the Antex soldering irons ous. Do not assume that the twin -lead and microwave regions. If we are not start at $19. For additional information, insulation will protect you if it contacts using them a lot, then we can expect contact M.M. Newman Corporation, 24 the electrical power lines. Never no assistance from the FCC. Tioga Way, P.O. Box 615, Marblehead, attempt to throw an antenna wire or If you want to keep up with WARC- MA 01945; Tel. 617 -631 -7100; Fax: transmission line across power 99 preparations, then let me recom- 617- 631 -8887. lines! The two insulations can cut into mend that you join the American Radio CIRCLE 78 ON FREE INFORMATION CARD each other, and if you touch such a Relay League (ARRL), 225 Main 75

AmericanRadioHistory.Com ELECTRONICS LibRARy

VISUAL BASIC FOR including OLE 2.0 programs; advanced ticulture, gravitation and electricity, WINDOWS 95 INSIDER: graphics routines; and system manage- cold light, and electric tornadoes. The The Guide to Hard -to-Find and ment programs. text also discusses Victorian -era elec- Undocumented Features Visual Basic for Windows 95 Insider: trostatic generator design, contains by Peter G. Aitken The Guide to Hard -to -Find and accompanying illustrations from turn - Undocumented Features costs $44.95 of- the -century patent applications, and Visual Basic for Windows 95 is the pro- and is published by John Wiley & Sons, provides hard -to -find information on gramming language used by serious Inc., 605 Third Avenue, New York, NY electrical anomalies. programmers who want shortcuts when 10158-0012; Tel. 800 -CALL -WILEY. Homemade Lightning: Creative developing Windows applications. This CIRCLE 80 ON FREE Experiments in Electricity, Second INFORMATION CARD book teaches users the latest undocu- Edition costs $19.95 and is published mented capabilities of Visual Basic for by Tab Books Inc., Blue Ridge Summit, Windows 95, so that they can accom- HOMEMADE LIGHTNING: PA 17294 -0850; Tel. 800-233 -11286. plish their everyday programming tasks CREATIVE EXPERIMENTS CIRCLE 81 ON FREE INFORMATION CARD more quickly and easily. IN ELECTRICITY Second Edition by R.A. Ford WORLD TREASURE NEWS from Fisher Research Laboratory Striking a delicate balance between Visual B challenging readers and confusing If you haven't yet been bitten by the them, this book is filled with useful pro- treasure -hunting bug, this newsletter for Windows 95 INSIDER jects for serious hobbyists, students, should do the trick. The 28 -page, mag- inventors, and experimenters. The azine-style newsletter documents valu- updated and expanded second edition able discoveries made around the world provides newly discovered information by people using Fisher metal detectors. on electrostatic generators and com- The unburied treasures include a plete, step -by -step directions for build- Confederate battle medal that fetched ing different types of generators; including Wimshurst and Van de Graaff.

Oil 2 -0 larking and Embedding Visual Bask, Word, Ferrel and Access Raro Civil War battle model found User Interlace and Multimedia Programnrng sraaaww.auar.

Readers learn how to master the new Windows Applications Program . . Interface (API), and how to link :rra-. ::.: IIINI-MbMl1I,00PKaN Windows 95 applications using OLE -E .v: u- 2.0. The book shows how to use Visual Basic for Windows 95 to create multi- H MOs x.ae.trra names missy pones arrwanl media applications and prototype appli- M elra Nae anrall Caaraaal M arnaMleC cations, write database programs for Microsoft's Access, and create graphi- . . - , cal front -ends for other programs. d The book explains how to get more Creative ExperAen.ts iar Electricity out of Visual Basic for Windows 95 by ECOND EDITION customizing the program to match the 'leA. Fard reader's style of working and individual $11,000 at auction, a forgotten 19th - goals. It provides many innovative Century cemetery, gold nuggets, the shortcuts, tricks, and techniques that The book thoroughly covers the wreck of a Civil War submarine that aren't documented anywhere else. theory of electrostatic generator oper- sank in 1867, a variety of weapons used The included diskette contains drop -in ation to give readers a solid foundation in crimes ranging from robbery to mur- code, including interface design compo- for the projects. Experiments include der, and solid gold Celtic coins dating 76 nents and tools; component applications, electroscope construction, electrohor- from the 1st Century B.C.

AmericanRadioHistory.Com The newsletter contains articles on meters such as AC and DC voltages, listing the more than 6000 circuits that archaeology, gold prospecting, under- amplification, frequency response, have been published to date in the six - water treasure hunting, new products, switching speeds, and input and output volume series. Together, those six and treasure -hunting clubs. Excerpts impedances. The design procedures books form a comprehensive refer- of an article that originally appeared in discussion presents step -by -step design ence that will allow readers to quickly the February 1939 issue of Science techniques for a wide range of op-amp and easily find the types of circuits and Mechanics Magazine describes circuits, including basic amplifiers, corn - they need. how to make your own two -box metal parators, oscillators, active filters, sig- The book is divided into more than detector. nal- processing circuits, and more. 100 circuit categories, including ama- The World Treasure News is free The book also presents trou- teur TV, amplifiers, battery chargers, upon request from Fisher Research bleshooting techniques that rely on the clocks, computers, fiberoptics, games, Laboratory, Dept. P -E, 200 West application of fundamental electronics lasers, light- control, Morse Code, oscil- Wilmott Road, Los Banos, CA 93635; principles, and it describes systematic lators, power supplies, radar detectors, Tel. 800 -M- SCOPE -1 or 209 -826- methods that can be used to diagnose scanners, timers, transmitters, and 3292; Fax: 209 -826 -0416. defects in many kinds of circuits that white -noise generators. CIRCLE 82 ON FREE use op amps. Encyclopedia of Electronics INFORMATION CARD Op Amps: Design, Application, and Circuits, Volume 6, costs $34.95 and is Troubleshooting, Second Edition costs published by McGraw -Hill Book OP AMPS: DESIGN, $49.95 and is published by Company, 11 West 19th Street, New APPLICATION, Butterworth- Heinemann, 313 York, NY 10011; Tel. 800 -2- MCGRAW. AND TROUBLESHOOTING Washington Street, Newton, MA CIRCLE 84 ON FREE INFORMATION CARD Second Edition 02158 -1626; Tel. 617 -928 -2500; Fax: by David L. Terrell 617- 928 -2620. CIRCLE 83 ON FREE TOOL & EQUIPMENT INFORMATION CARD This easy -to-read book deliberately CATALOG #55 straddles the imaginary line between from Techni-Tool the technical and engineering worlds. ENCYCLOPEDIA OF Technical details of operational ampli- ELECTRONICS CIRCUITS This 254 -page, full -color catalog fea- fiers are explained in clear and under- Volume 6 tures hundreds of products for elec- standable language without sacrificing by Rudolf E. Graf & William Sheets tronics professionals and hobbyists. technical depth. Product categories include cases and Topics are carefully addressed on Like each of its five predecessors, tool kits, cleaning and safety supplies, three levels. The operational overview Volume 6 of this popular series contest instruments, soldering and desol- describes the purpose and explains the tains more than 1000 state -of- the -art dering gear, telecommunications and electronics circuits, most direct from fiber optics, pliers and cutters, strip- the manufacturers, some designed by pers and crimpers, production tools, the authors, and others collected from ESD control, workstations and chairs, books and magazines. To make it easy and magnifiers and lights. The catalog Op Amps for readers to find what they need, the provides a photograph and full

DESIGN, circuits are arranged alphabetically by description of each item offered. Also APPLICATION, AND type. The book's index is cumulative, featured is Techni -Tools "Design -A -Kit" TROUBLESHOOTING

lrenter-r®®íf.

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mow 1

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operation of each op -amp circuit from an intuitive and non -mathematical point of view. The numerical analysis shows how to calculate important circuit para- 77

AmericanRadioHistory.Com service, which allows you to specify time -saving programmer utilities cuits; voltage dividers and power; precisely which tools you want -and including a Line Number filter, a Kirchoff's Laws; advanced methods of don't want-in a tool kit. Comment filter, and an API extractor. DC circuit analysis; capacitors and the Catalog #55 is free upon request Java for C /C ++ Programmers RC time constant; and inductors and from Techni-Tool, 5 Apollo Road, Box costs $39.95, including disk, and is the L/R time constant. 368, Plymouth Meeting, PA 19462; Tel. published by John Wiley & Sons, Inc., Basic Electricity & DC Circuits costs 610-941 -2400; Fax: 610 -828 -5623. 605 Third Avenue, New York, NY $34.95 and is published by Prompt CIRCLE 85 ON FREE 10158 -0012; Tel. 800 -CALL -WILEY. Publications, 2647 Waterfront Parkway, INFORMATION CARD CIRCLE 86 ON FREE East Drive, Indianapolis, IN 46214- INFORMATION CARD 2012; Tel. 800 -428 -7267 or 317-298- JAVA FOR C /C ++ 5710; Fax: 317 -298-5604. PROGRAMMERS BASIC ELECTRICITY & DC CIRCLE 87 ON FREE INFORMATION by Michael C. Daconta CIRCUITS CARD by Charles W. Dale, Ed.D. Most C and C ++ programmers already ELECTRONICS TERMINOLO- have some of the skills needed to write This book requires no previous knowl- GY:A Concise Dictionary simple Java applets. This book helps edge of electricity or sophisticated compiled by Informatik Rezurch them take the next step to become mathematics. It allows readers to learn proficient in Java. about electricity from the ground up, at This pocket -sized book provides up -to- The book teaches Java by building their own pace. Concepts and terms date, succinct definitions of electronics on C and C ++ concepts. Taking read- are introduced as they are needed, jargon for technicians and engineers on ers beyond applet development, it with many detailed examples and the move. The book's first section con- trains them on how to exploit the lan- explanations. tains translations of acronyms ranging guages' similarities. The book explains from "A" (angstrom unit) to "ZnO" (zinc how to program proficiently using oxide). The second section offers many Java, the Java Abstract Window Toolkit, and applets. It teaches readers how to develop large- scale, multi -platform, networked Java applications in days. It álso presents the basics of £LECTONICS JavaScript programming and shows readers how to incorporate JavaScript code into Web pages. ifNNINOLGV

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Each topic is presented as a corn - plete lesson, with its objectives stated up front and with three different types of examples to wrap up. Worked - through example problems apply the theory taught in each lesson to real -life straight forward definitions of electron- situations involving DC 'C /C electricity. Next, ics, packaging and production, comput- readers can test their new skills by try- er, and semiconductor terms. Many ing to solve a set of practice problems. acronyms and definitions are cross -ref- Finally, a two -page quiz serves as an erenced to provide complete coverage. indicator of areas requiring further Electronics Terminology: A Concise The book comes with a disk that study. Dictionary costs $12.95 and is pub- includes more than 100 complete Java Lesson topics include an introduc- lished by Butterworth- Heinemann, 313 and JavaScript source code examples tion to electricity; voltage, current, and Washington Street, Newton, MA from the text; useful Java applications resistance; scientific notation and met- 02158 -1626; Tel. 617 -928 -2500; such as a database management sys- ric prefixes; Ohm's Law and power; Fax: 617 -928 -2620. tem, a graphical reminder application, series circuits; parallel circuits; paral- CIRCLE 88 ON FREE INFORMATION CARD 78 and a multi-threaded simulation; and lel- series circuits; series -parallel cir-

AmericanRadioHistory.Com DIGITAL PANEL METERS length of copper clips is about 0.1 mil - (Continued from page 44) liohm.) DPM SUPPLIERS An LM317T adjustable voltage reg- All Electronics Corp. ulator, ICI, is used as a current limiter; P.O. Box 567 tance or along the length of the cur- ICI limits the voltage between its out- Van Nuys, CA 91408 -0567 rent- carrying jaws. put and adjustment terminals to 1.25 Tel. 800 -826-5432 Fax: 818 -781 -2653 For a 31/2-digit DPM, Kelvin Clips can volts, and R5 and R6 are chosen to Stock -number PM -128 (31/2- digit) also be used, but heavy solid -copper have that voltage drop at the desired clips (also made by Mueller and avail- current. At low currents, the resistance B.G. Micro, Inc. P.O. Box 280298 able from Mouser Electronics and must be slightly higher than the calcu- Dallas, TX 75228 Hosfelt Electronics) will also work and lated value; for 10 mA, R6 should be Tel. 800 -276 -2206 are much cheaper. For copper clips, about 135 ohms, but this might vary Fax: 214 -271 -2462 you have to move them slightly, after slightly for different LM317Ts. In the Stock -number PM -128 (31/2- digit) clipping them on the object to be prototype, a 200 -ohm multi -turn trim- Black Feather Electronics measured, to get the lowest resis- mer potentiometer was used for R6, 645 Temple Avenue #7 tance. (The resistance along the and was calibrated by measuring Long Beach, CA 90814 Tel. 800 -526 -3717 several precision resistors. An alter- Stock -number PM -1 (3'h- digit) nate calibration method is to connect Circuit Specialists, Inc. PARTS LIST FOR THE a milliammeter to the test leads and P.O. Box 3047 LOW -OHMS METER (Fig. 9) adjust R6 for a reading of 10 mA. The Scottsdale, AZ 85271 -3047 calculated value for R5 is 12.5 ohms; Tel. 800 -528 -1417 SEMICONDUCTORS the nearest standard 1% resistor value Fax: 602 -464-5824 ICI- LM317T adjustable- voltage Stock- numbers PM -128 (31/2- digit) and is 12.4 ohms. Because there is a slight regulator, integrated circuit PM -328 (41/2- digit) variation in LM317Ts from the QI- 2N3904 general- purpose NPN specified 1.25 volts, measure a few units to Hosfelt Electronics, Inc. transistor 2700 Surset Blvd. find one having the closest output to Q2- 2N3906 PNP transistor Steubenville, OH 43952 -1158 DI- 1N4001 silicon rectifier diode that value. An alternative would be to Tel. 800 -524 -6464 D2- 1N4742A 12 -volt Zener diode use a 20 -ohm trimmer potentiometer Fax: 800-524-5414 D3 -Zener diode (optional. see text I for R5. Stock -numbers 39 -165 and 39 -177 (3'h- digit) and 39 -176 (41/2- digit) LEDI- Low- current light- emitting When the current is at the limit of 10 diode (see text) mA or 100 mA, LEDI lights. If LEDI is dim, Jameco Electronics 1355 Shoreway Rd. RESISTORS the battery is getting weak. Compo- Belmont, CA 94002 -4100 (All resistors are'/ -watt, 5% units, nents Q2, R2, R3, and R4 make up the Tel. 800 -831 -4242 unless otherwise noted.) control circuit for LEDI. The LED is a Fax: 415 -592 -2503 R1 -See text and Table I low- current type, needing only 2 mA Stock -numbers 108388 or DPM128 R2- 10,000 -ohm to 2.5 mA, which extends the life of B1 (31/2- digit) and 123140 or DPM328 (41- R3- 2200 -ohm and also gives a better indication digit) R4-3300 -ohm (than a standard LED) if the current is Marlin R Jones & Assoc. Inc. R5- 12.4 -ohm, I% below the limit. RadioShack offers a P.O. Box 12685 R6-135 -ohm (see text) Lake Parc, FL 33403 -0685 red, low- current LED (number R7- 180,000 -ohm, 1% Tel. 800 -0K-2 -ORDER R8- 20,000 -ohm, 1% 276 -044). Another source is Digi -Key Fax: 800 -4- FAX -YES Corp.; they have red (number Stock -numbers 6929 -ME (31/2-digit) CAPACITORS HLMP- 4719QT -ND) and yellow and 7160 -ME (41/2- digit) Cl, C3- 0.1 -µF, Mylar or ceramic - 4710QT -ND). disc (number HLMP- Linrose C2 -Mylar or ceramic -disc (see text Electronics Inc. has three case styles, and Table 1) each in three colors (red, yellow, or tary switch was used for S2, with one C4- 22 -11,F, 16 -WVDC, electrolytic green, series 4300F 4300H, and pole not used. C5- 100 -I1,F, 25 -WVDC, electrolytic 4300T), which are sold by local parts In building the prototype, the reg- distributors. ulator was mounted to the case, and ADDITIONAL PARTS AND MATERIALS Zener -diode D3 can be used if de- its terminals were used as tie points. T1 -600- to 600 -ohm, center -tapped sired to protect the DPM from high Components Q2, R2, R3, and R4 were transformer (see text) voltage accidentally applied to the mounted on the extra pads of the DC- S1 -SPDT miniature slide or toggle test leads. It is selected in the same to-DC power supply board. No pilot switch manner as was D3 in Fig. 7. On the 4Y2- light is used; if one is desired, another S2 -3P3T rotary switch (see text) digit DPM used in the prototype, the 3300 -ohm resistor and low- current B1 -9 -volt alkaline battery common point for the decimal -point LED could be used, connected from Perforated board, enclosure jumpers was not connected to the the input terminal of ICI to the nega- (RadioShack number 270 -222 or common point for voltage input, and tive terminal of B1. Total parts cost is similar). DPM module, battery S2 as in Fig. 9. about $35 if a 31/2-digit DPM and cop- snap, zip cord (18- or 20- gauge). -b was wired shown test clips (see text), wire, solder, Again, the order of the decimal -point per test clips are used. For a 41/2 -digit hardware, etc. jumpers varies on different DPMs. In DPM and Kelvin clips, the total parts the prototype, a 4 -pole, 3- position ro- cost of the unit is about $60. 79

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quency up to 1 MHz Specifications: Vertical deflection: Bandwidth :DC ccupled (DC to 20MHz normal), _ r AC coupled :(10Hz to 20MHz normal) Deflection factor: 5mV /div to 5V/ 2 div in 10 calibrated steps of 1 -2 -5 sequence Rise time: 17.5nS or less 41 1 II I 1141 Replaces A: to in 19 uq,. [._ 226-1 Horizantal deflection: Time Base 0.2ps 0.2S /div calibrated GOLDSTAR 154 -074R steps.1 -2 -5 sequence Uncalibrated continuous control between steps $20 MINIMUM ORDER ORDER N° 63 -0189 of at least 1: 2.5. CALL NOW FOR YOUR 232 PAGE FREE CATALOG TUN -O -WASH® DIGITAL MULTIMETERS DALCO ORDER No 30 -0100 NEW! NS-4-4-1 1 -800- 325 -2264 Overload protect 1000VDC or peak AC on all other ranges Input impedance 10M Ohm on IOT PRICES ON POPULAR SEMI'S (CFC Fitz) all ranges Base accuracy range ± order N. Brand Min Price Fast drying electronics ± 0.5 % to 1.0 % Resistance 2K, 20K, 200K, 2M, 20M ,U -208 TESLA 10 $1.49 trade cleaner for tuners, 2000, Audible ' esponse IU -208/0 TOSHIBA 1 4.50 controls and PC boards. continuity N -3055 TESLA 10 0.60 TUN -O -WASH is excellent cleaner and lower than 500 DC Voltage N -3773 TESLA 5 1.20 . degreaser for tuners, controllers and PC boards. 200mV, 2V. 20V, 200V, 1000V SD -1398 SANYO 10 1.49 AC Voltage 200mV, 2V, 20V, SD -1650 5 1.69 SANYO Designed for cleaning and degreasing 200V, 700V iTRD -1005 SANKEN 1 4,15 consumer electronics Cleans in one step, no ITR -30130 SANKEN 1 2.66 r nsing required Contains no ozone depleting ORDER N° 50 -815 iTRS -6301 SANKEN 1 8.50 compounds CFC and HCFC free 'A-7777N TOSHIBA 1 6.96 DA-2005 SGS 5 1.49 Not for use on energized equipment 12.5 Oz aerosol (12 cans per case) LOGIC Probe 11111011M' - ORDER No 51 -1015 OLOR CODED VCR ALIGNMENTTOOL KIT Length: 8 inches EADS HEAVY DUTY Range: 4.5 To 15 VDC ORDER # 50 -888 RDER N° 56 -500 24.92 Includes Test Leads Compatible With T& TTL,DTL,RTL,HTL,CMOS, NMOS Logic I1" Long Wire Lead nsulated 112" Alligator Clips VCR Head puller 20 Gauge Wire Size 10 Leads Retaining ring SOLDER ROLL SLACK, GREEN, RED,YELLOW, WHITE remover 1 LB Spool Spring hook 370 deg F melting point OLDER WICK Micro screwdriver Fastest solder Hex key set Fitted vinyl Soft zippered case Alloy 60/40, tin lead, non Solder Remover 850 Dimensions: 91/2 "(W) X 121/4 "(L) corrosive flux, Diam. 1.2mm Length Feet 5 vJw: 7 Assorted head & guide aligners ORDER N° 51 -1005 $3.9 Min. 2 pcs. 34 RDER N° 51 -1050 3 Reverseable screwdrivers (Small -Flat- Philips) fir.: Audio /video Remote TEMPERATURE CONTROLLED ,__ Universal MAGNAVOX ORDER N°, 82 -1055 Smart. Very smart SOLDERING STATION Controls basic functions of TV, Adjustable Temp.: 300 °F - 790 °F - 150 °C - 480 °C VCR, cable box, and CD or laser

Grounded Tip for Soldering : player Ergonomic design! Main Static Sensitive Devices, Heater Aid. buttons are in line with natural Led Power Temperature Indicator thumb motion Two-minute memory al- Cable (11 brands) Overheat Protection W/ Temperature Control lows time to replasce batteries without re- VCR (68 brands) programming Programming reminder sticker Auxiliary Grounded Terminal TV (77 brands) inside battery compartment Sleep time for 60, Comes in digital LED display Compact disc and 30, or 15 minutes(according to your TV) Set key 48 Watts iron soldering recessed to prevent accidental deprogramming Laser Disc (94 brands) Spanish instruction included. Requires four AM ORDER No 51 -1035 Batteries (not included)

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2 BANANA PLUGS Alps # MDLK5A -1 COOLER MOLDED BREAKOUT Standard video-RF modulator with F connectors for PELTIER JUNCTIONS CABLE antenna in and out, RF Off /through switch built -in and ITT Pomona #3957 Channel 3 and 4 outputs. Meets Designed to convert NTSC specifications. Operates on 5 Vdc, 35 standard coaxial ma max. 1.75" X 1.75" X 0.75" Includes spec cable to test and hook -up sheets. cable. By 50 CAT # AVMOD -5 These incredible connecting $6 each miniature solid BNC connector to cable, state heat pumps raise it becomes equipped with SET OF 12, SPOT NUMBERED or lower temperature in a small separate banana plugs for shield and center LIGHTED SWITCHES area almost instantly. Utilizing the Peltier conductor. Overall length 7". 50 effect these modules perform the same cool- CAT# PRB -7 $45° Twelve push -on /push -off ing or heating functions as freon based refrig- switches (only 6 pictured). 0 erators but they do it with no moving parts, 1.06" DIAMETER Each switch has a 0.6 and are very reliable. Current applied to the device will produce heat on one side and cold square yellow lens with"© a 16 \/ on the other side, up to 68° C PIEZO ELEMENT 0.25" high black numeral 1 difference through 12. They are light- between the two sides. Modules can be mounted in parallel to increase the heat ed by a 28 volt, #85 I trans- wedge , , fer effect or can be stacked to achieve high base incandescent lamp which 1,, can be easily replaced it a different differential temperatures. 127 thermocouples Piezo elements can be used with an external voltage is desired. per device. Operates on 3-12 Vdc. Requires signal source in order to produce a tone. They 00 a heatsink to prevent overheating. CAT #PBL -12 $ par set of 12 are frequently used as pick -ups and vibration 5 sensors. 8" long pigtail leads. CAT# PE -32 1.18" (30 mm) square ULTRA -BRIGHT LED X 0.15" (3.8 mm) thick. 10 for $8.50 Rohm # $1 each 100 for $65.00 SLA- 580MT -E49 T-1 3/4 CAT# PJT-1 GREEN, water clear in off state. 500+ mcd $1 / each 5 for $75.00 @ 2.1 y, 16ma. OO "HI -8" VIDEO CASSETTE CAT# LED -33 2 for $1 00 1.57" (40 mm) square (USED) 100 for $40.00 1000 for $300.00 X 0.15" (3.8 mm) thick. 1 CAT# PJT -2 ATTENTION CAMCORDER USERS! 5 for $110.00 ( OPTOISOLATOR MODULEI $2600%h SONY Hi -8 Top quality, metal Vactec #VTL5C4 Quantity Pricing Available! particle 120 minute Combines a LED video cassettes. Used light source with a SPECIAL SALE! for a short time, then ILVel'm photoresistor for input- output isolation. Used for METAL OXIDE VARISTOR 101 noiseless switching, photocopiers, bulk- erased. Each cas- linear isola- sette has its own plastic tors, proportional control circuits. External cur- Harris / GE # V130LA20B or equivalent storage box. Satisfaction rent limiting resistors required. LED current 40 130 Vac nom. 70 Joules Guaranteed. Ma max. @ Vf =2V. Axial plastic package, 0.38" Peak pulse current: 6,500 amps. CAT # VCU -8 long x 0.4" diameter. OO $1 00 CAT# MOV- 130 -20 10 for $28.00 100 for $250.00 CAT# VTL -5C4 "'2 each each 100 for $75.00

ORDER TOLL FREE 1-800-826-5432 MAIL ORDERS TO: FAX (818) 781 -2653 INFO (818) 904 -0524 ALL ELECTRONICS CORP. P.O. BOX 567 http://www.allcorp.com/ VAN NUYS, CA 91408 -0567 E -MAIL [email protected] 143 NO MINIMUM ORDER All Orders Can Be Charged to Visa, Mastercard, American Express or Discover Checks and Money Orders Accepted by Mail Orders Delivered in the State of California must include California State Sales Tax NO C.O.D Shipping and Handling $5.00 for the 48 Continental United States - ALL D`IVEP OTHERS including Alaska. Hawaii. P.R. and Canada Must Pay Full Shipping Quantities Limited Prices Subject to change without notice. MANUFACTURERS - We Purchase EXCESS INVENTORIES... Call, Write, E -MAIL or Fax YOUR LIST. 88 CIRCLE 28 ON FREE INFORMATION CARD

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Press a button and Our TV filters learn every number TV NOTCH FILTERS eliminate unwanted TV dialed on your phone FOR CHANNELS channels or interference

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AmericanRadioHistory.Com RADIO AMATEURS Putting it all Together. From the this fascinating and rewarding avoca- (Continued from page 52) foregoing, you can see that there are tion a try -if you do, you won't be sor- many diverse aspects of amateur ra- ry. operation with your radio trans- dio-so many that hams can easily ceivers. With multimode controllers, pursue the hobby too intensely, to the Becoming a Ham. Anyone can be- you may at once be able to operate exclusion of friends, family, and the come a radio amateur, regardless of Packet, PacTOR, AMTOR, RTTY SSTV FAX "real world" community around them. age, gender, or physical ability. Hams and Weather FAX (WeFAX), CW, and After all, even in this high -tech, digital include students, retirees, young peo- several other new -tech modes. world, amateurs still are real people, ple, old people, clergymen, mechan- 17. Use their PCs: Do you own or not virtual ones. ics, technicians, homemakers, doc- use a PC? If so, that's great, since few There's a long- standing Amateur's tors, engineers, pilots -just about activities go together as well as per- Code that helps puts those things to- anyone, including yourself. People sonal computing and amateur radio. gether. Originally written by Paul M. from all walks of life and of all ages Today's technology lets amateurs link Segal, W9EEA, in 1928, the Code has can and do pass the amateur exams. their PCs to their radio equipment, to been adopted by the ARRL, and it's still Best of all, getting an amateur -ra- perform many tasks in the hamshack meaningful today. While perhaps a bit dio license is easier than you might that make an already enjoyable hob- idealistic in its "mom and apple pie" think, especially since 1991, in that you by much more fun. And, best of all, approach, it properly stresses that the no longer have to learn Morse code. you don't have to be a computer radio amateur is balanced, never in- And even entry -level (Novice, Techni- whiz to take advantage of the tech- terfering with the pleasure of others; cian, and Technician Plus) licenses let nology, loyal to other amateurs; progressive, you use voice and the latest digital However, one hang -up has been with his operations above reproach; and computer -based technologies software. Until just a few years ago, friendly, offering advice and counsel on the air. hamshack PC software was quite lim- to beginners; balanced, with amateur Of course, to obtain a license, you ited, and it focused mainly on QSO radio an avocation that shouldn't in- must pass an exam. In 1985, the FCC and contest logging. Today, software terfere with duties to family, job, set up a program whereby licensed has emerged that lets you use your PC school, or community; and patriotic, radio amateurs called Volunteer Ex- for much more, including a dozen - with station and skills made available aminers (VEs)- amateurs in the com- and -a -half distinct classes of software for service to country and community. munity who volunteered their services applications, such as: Morse Code Very good advice for yesterday, the as test -givers -were organized into and radio theory practice, instruction, present, and especially the future. testing teams by several (now 16) and testing; computer -based radio A good way to keep up with the FCC -authorized Volunteer Examiner and station control; logging, con- hobby and its practitioners is to go Coordinator (VEC) groups. testing, and awards tracking; auto- online, either with one of the online The VECs are certified by the FCC to mated QSL card processing; direc- communications utilities such as administer exams; questions are tional antenna aiming; radio propa- America Online and CompuServe, or drawn from a regularly updated gation prediction; antenna design on the Internet (especially the World - question pool developed by the FCC and modeling; satellite tracking and Wide Web). Be sure to check out the and the VECs. The VECs conduct antenna control; CW and RTTY recep- Ham Radio Club (Keyword: HAM or exam sessions, often held at hamfests. tion and transmission; and packet ra- HAM RADIO) and ARRL areas (found in Although the FCC doesn't charge to dio and other digital communica- the Ham Radio Club) on America issue or renew licenses, the VECs may tions. Online, and the HamNet Forum (GO charge nominal fees. Other computer applications in- HAMNET) on CompuServe. The Com- The VECs administer the exams for clude graphical (image) communi- puServe HamNet Forum is especially the Novice, Technician, Technician cations such as FAX, SSTV WeFAX, and useful in that it has a number of areas Plus, General, Advanced, and Extra FSTV (fast -scan TV); electronic circuit in which you can exchange mes- "tickets." Although you can initially design and performance calculation; sages and download software files re- qualify for any of the operator classes, CD -ROM based callsign lookup; and lating to most of the activities and most people find the Novice and various forms of online communica- interests we discussed. There also is Technician /Technician Plus licenses tion, including the Internet. You could the related HamNet Companion In- are ideal entry points. They give you, also add a "miscellaneous" classifica- ternet Web page, found at http: // as a newcomer, access to a consid- tion to include multipurpose www.webcom.com /sjI /HamNet- erable number of frequency bands hamshack software to logically inte- Companion/. without a too -difficult examination. grate a variety of functions for max- As we've seen, amateur radio defi- Let's look at each: imum efficiency and convenience. nitely isn't a trifling hobby despite its Technician: The Technician class li- Indeed, as we transition to Windows rather obscure origins, its sometimes cense is aimed at folks with a tech- 95, OS /2, and other graphical, multi- unusual pursuits, and its strange jar- nical bent, though you don't have to tasking environments, traditional soft- gon. And, since it is one of the few be an electrical engineer to qualify. ware classifications will blur as hobbies for which you have to be li- The "no- code" Technician Class hamshack tasks become more de- censed to participate, hams appreci- doesn't require that you know Morse manding and programs multifunc- ate the hobby even more for its strict code -you must just pass a relatively 104 tional and better integrated. entry requirements. Maybe you'll give easy exam on radio operating prac-

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Connects between a TW523 and Conr'ects between a telephone Connects to telephone wall jack. Disables Reads frequency from 1 Hz to 50MHz and an RS-232 serial port. Use your PC wall ack and an RS-232 sera) all phones on the line if attempting to displays up to 7 digits on a 18x1 character or Mac to receive and transmit all port Decodes the caller ID data either: dial a number that has been stored LCD ásplay. Auto -range feature provides X -10 commands. Create your own sent over the phone line and in memory 'Block' mode or, dial a number floating decimal point and automatically program to control your home sends it to your PC or Mac, in a that has not been stored in memory affixes the correct suffix (Hz, KHz, or MHz). automation system, turning on/off pre-formatted ASCII character 'Allow' mode. Use touch -tone phone to Microcontroller based provides for very any device plugged into an strinç. Create your own program enter telephone numbers into memory, small parts count, only 2' x 3' big. electrical outlet with responce to to log the name, number, date, and choose mode. Program from any time /date, other X -10 transmissions and tome of all Incoming calls. phone on the line using your password. or any other computer Input stimuli. DTMF Decoder /Logger Vocal Filter IR Remote Control Receiver Peep track of all numbers dialed or Telephone Scrambler An audio device which can be entered from any phone on your Scrambles your voice before Leans and records the data patterns used with a home component tine. Connects to your telephone sending it over the telephone emitted by standard infrared remote stereo system to fitter out the wall jack. Decodes all 16 touch - line. Prevent eavesdropping from controls used by TVs, VCRs, Stereos, etc. main vocal sound track from tones and displays them on an LCD an extension or tap. Connects Lets you control all your electronic projects standard stereo recordings (CD, cisplay. Holds the last 240 digits in between your telephone and wall wth your TV remote. Seven Individual I/O tape, record or FM), leaving the a nonvolatile memory. Scroll jack. No modrfications are pins can be assigned to any button on your background music to sing along through and view all telephone required to your telephone. Full remote, and can be configured for either with. Produce your own karaoke numbers dialed, credit card duplex operation. *toggle' or 'momentary' action. tapes from your personal library. rumbers entered, etc. 105

AmericanRadioHistory.Com tices, FCC rules, and basic electrical ileges across most parts of all bands, study guides, including the ARRL book, theory. It offers all amateur privileges except for the relatively few sub -band Now You're Talking! All You Need to Get in the 6 -meter (50 MHz) and higher privileges that are reserved for the Ad- Your First Ham Radio License (see the (VHF /UHF) bands. Technician Class op- vanced and Extra Classes. "Bibliography" for more information). erating privileges include FM voice, Advanced: A somewhat tougher digital packet, satellite, television, sin - written theory examination charac- gle-sideband voice, terizes the Advanced Class license. and several BIBLIOGRAPHY other modes. Roughly descended from the old Technician Plus: The Technician "Class A" amateur license, it gives all American Radio Relay League, Inc. Class operator who has successfully privileges of General Class licensees, Now You're Talking! All You Need to Get completed the Morse code require- plus some additional frequency-of- Your First Ham Radio License, Second ment is known as a "Technician Plus." operation privileges in portions of the Edition. Newington. CT: ARRL, 1993. The frequency bands for the Techni- HF bands. Like the General, the Ad- American Radio Relay League, Inc. The ARRL Operating Manual, Fifth cian license give you access to "local" vanced Class exam requires a 13- Edition. Newington, CT: ARRL, 1995. communications, But you also can use WPM Morse test. Benicia Amateur Radio Club (ARC). the Morse test to gain access to the Extra: At the pinnacle of the ama- Log Book Newsletter Benicia, CA: June long -haul bands, the same as the teur -radio licensing structure is the 1989. Burgoyne, Dennis, KE8EY Letter to Novice class. Thus, as a Technician Amateur Extra Class license, with a still - the editor. CompuServe Magazine. De- Plus, you're also allowed Novice -type stricter exam and a somewhat daunt- cember 1990. operating privileges in the popular 10, ing Morse code requirement of 20 Helms, Harry, AA6FW. All About Ham 15, 40, and 80 -meter high frequency WPM. The license authorizes unre- Radio. San Diego, CA: HighText Pub- (HF) shortwave bands (see below). stricted, full -privilege operation on all lications, Inc., 1992. Johnston, Bill, WB5CBC. "From Novice: The Novice Class license is amateur bands as an incentive for Whence Came Ham." OST November for beginners who don't have the amateurs to pursue the Extra ticket. 1976. technical knowledge to pass the Relatively few amateurs go all the way Luchi, Larry R., W7KZE. Luchis Ama- Technician -level theory and regula- to the Extra, however, perhaps believ- teur-Radio License Guides. (Set of four tions exam, but who can pass the rela- ing that the few additional privileges guides: Novice, Technician, General, and Advanced.) Lake WI: Tiare tively simple Novice justify Geneva. -level FCC theory don't the effort required to Publications, 1995. and regulations exam and the 5 -WPM achieve it, Mansfield, Steve, N1MZA. Letter to the Morse code test. Privileges include editor. Popular Electronics. December voice operation in the 10 -meter band Getting Exam Information. To pre- 1993. Pyle, Howard S., W70E. "Evolution of and Morse in the 10, 15, 40, and 80- pare for the exams, you'll need study the Ham Shack." CO. August 1966. meter shortwave bands, as well as op- materials and more information Thurber, Karl T, Jr. "What's a Ham ?" eration on some "local" VHF /UHF about classes, examination points, Popular Electronics. May 1993. bands. Since the Novice class gives a and clubs in your area. For details on range of HF privileges, it's attractive to getting started in amateur radio, con- those with a desire to talk to those far- tact your local amateur radio club or ili>iJon 11LDILa MULTIMEDIA away places. one of the Volunteer Examiner Coor- on theth PC The three top license classes are dinators (VECs). There are 16 VECs (see on the PC! General, Advanced, and Extra. If the "Volunteer Examiner Coordi- What is Multimedia? What can you're a licensee of one of these three nators" box). it do for you? It can do lots of nice things! This 184 -page classes, you have access to A number of portions organizations are book helps you create your of all amateur bands, but you have to more than willing to help. One of own multimedia presentation. contend with progressively more diffi- these is the American Radio Relay Multimedia applications by people like you can cult exams, and requirements for League (ARRL), the national organiza- revolutionize educat onal and business applications as well as bring more FUN, FUN, FUN into copying faster Morse code (13, 13, tion of amateur -radio operators. The your leisure computer activities. and 20 WPM, respectively). Bear in ARRL distributes a free "Getting Start- mind that, as you progress up the li- ed in Ham Radio" information pack- Mail censing ladder, you're given credit for age that you can obtain as a first step. coupon to: all exams or parts of the exams, such Ask for it by calling the New Ham Electronics Technology Today, Inc. as a code test, that you've previously Hotline at 800 -326 -3942. The material P.O. Box 240 passed. Here are some more details describes amateur -radio and popu- Massapequa Park, NY 11762 -0240 of each license: lar ARRL study guides. It also includes a Please send me my copy of Multiomedia on the PC (PCP120). I enclose a check or money order for $18.95 If there customized list local -radio General: ever was such a of amateur to cover the book's cost and shipping- and -handling thing as a "standard- class" amateur clubs, ham -radio classes, and volun- expenses. NY state resident must add local sales tax.

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AmericanRadioHistory.Com ADVERTISING INDEX Popular Electronics does not assume any responsibility for errors that may appear in the index below. ADVERTISING SALES OFFICES Free Information Number Page Free Information Number Page Gernsback Publications, Inc. 500 Bi- County Blvd. 25 Ace Communications 1(0 - Mana 105 Farmingdale, NY 11735 -3931 AES 1 -(516) 293 -3000 - 107 154 MCM Electronics 85 Fax 1 -(516) 293 26 Alfa Electronics -3115 84 - MD Electronics 89. WI Larry Steckler, EHF /CET 28 All Electronics 88 Mega Electronics 114 President (ext. 201) Allison Technology 1 I 1 152 Mendelson's 117 Christina Estrada Assistant to the President - Alistar Electronics 112 Mental (ext. 209) - Automation I l l For Advertising ONLY AMC Sales 101 157 MicroCode - Engineering 3 1- 516- 293 -3000 - American Innovations 96 Millennium Fax 1- 516- 293 -3115 - Enterprises I I I - Andromeda Research 113 Modern Larry Steckler - Electronics 110 publisher Basic Electrical Supple 94 Mondo- tronics 9(1 - Arline Fishman 30 Bel -Merit 112 138 Mouser 107 advertising director (ext. 206) 32 C &S Sales, Inc 92 - NRI Schools 35 Michele Torrillo Circuit Specialists advertising assistant (ext. 211) 98 43 Optoelectronics CV4 Adria Coren - Cleveland Institute of Electronics .19 Orion Electronics - 110 credit manager (ext. 208) Command Productions - 96 156 Parallax CV3 Computer Business Services Subscription/ - 15 150 Parts Express 110 Customer Service/ - Comtrad Industries 5 9. 25 149 Phillips Tech Order Entry 112 1- 800 -827 -0383 Consumertronics 102 47 Prairie Digital Inc. 95 7:30 AM - 8:30 PM EST 139 Dalbani 87 46 Print 95

162 Davis Instruments 10 45 Print 101 - Desert Cable 116 Quality - Entertainment 100 136 Electronic Rainbow 91 14 ADVERTISING SALES OFFICES Radio Shack 11 EAST /SOUTHEAST - Electrician School 110 The Satellite - Center I l l Electronic Stanley Levitan Technology Today 81 Show -Time 97 - Eastern Sales EMAC - 94 Silicon 1 - Valley Surplus 110 Overlook Ave. Foley- Belsaw Great Neck, NY 11021-3750 115 - Skyvision Inc 82 1- 516- 487 -9357, 1- 516- 293 -3000 Forest Electronics - 96 153 Sun Equipment 86 Fax 1 -516- 487 -8402 Fotronic Corporation 83 MIDWEST - Tab Books 13. 55 /Texas /Arkansas/ Oklahoma, Colorado, Arizona General Device Instruments 110 155 Telulex 97 Ralph Bergen Grantham College of Engineering.4 151 UCANDO Videos 95 Midwest Sales Greenleaf Electronics Inc. 94 US Cyberlab 107 One Northfield Plaza, Suite 300 Northfield, IL 60093 Halcyon Group 1(0 -1214 Vision Electronics 112 1- 847 -559 -0555 Home Automation Systems 113 Fax 1- 847 -559 -0562 Visual Communications 110 I.E.0 [email protected] 15 159 Wavetek Corp. 7 PACIFIC COAST /Mountain States Information Unlimited 97 Weeder Technologies 105 Anita Bartman 13 Interactive Image Technologies CV2 Weka Publishing 109 Hutch Looney & Assoc., Inc. 6310 San Vicente Blvd. Intronics, Inc. 110 Windjammer Barefoot Cruises ....10 Suite 360 Kableworks 117 World College (Div. of C.I.E.1 23 Los Angeles, CA 90048 -5426 1- 213- 931 -3444 (ext. 227) KDE Electronics 105 WPT Publications 116 Fax 1- 213- 931.7309 Learn Inc. 134 Xandi Electronics 103

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118

AmericanRadioHistory.Com BASIC STAMP®COMPUTERS Tiny computers run BASIC programs

BASIC Stamps are component -sized computers that run BASIC programs. They have 8 or 16 I/O lines, which can be used for a variety of digital and analog purposes. And their BASIC language is both familiar and extensive; the language includes FOR...NEXT, Marvin Green and his students in Hillsboro, Oregon, use BASIC Stamps to make small robots. IF...THEN, and GOTO, as well as XOUT, SHIFTOUT, DTMFOUT, and other special commands.

We've been making BASIC Stamps for several years, and we've accumulated some interesting photos along the way. In this ad, we thought it might be fun to show some of these photos.

BS1 -IC Module $34 8 I/O lines 80 instructions max. 2000 instructions /sec. John McLean uses BASIC Stamps to gather data in Lechuguilla Cave (America's deepest cave, lo- 2400 baud serial I/O cated in Carlsbad Caverns National Park). 14 -pin SIP module FaxBack I/O instructions for pushbuttons, #6002 potentiometers, pulse measurement, PWM, serial I /O, sound, etc. BS2 -IC Module $49 16 I/O lines Programming Package $99 500 instructions max. Contains programming materials 4000 instructions/sec. needed to program BASIC Stamps; 50k baud serial I/O includes cables, PC software, 24 -pin DIP module manuals, and free tech. support. Same I/O instructions as BS1, plus touch -tones, frequency Charles Walsh and his students in Great Falls, generation, pulse counting, Montana, use BASIC Stamps in robotics projects. Carrier Boards $15 -$20 serial shift registers, X -10 Provide small prototyping area, 9- powerline control, etc. I/O volt battery clips, and program- functions common to both ming connector. Not absolutely modules have a higher reso- necessary, but recommended to lution on the BS2 -IC, due to make programming easy. its faster clock speed.

Data Collection Board $179 This nifty board from Scott Edwards Electronics provides everything you need to use the BS2 -IC as a data logger. Includes ample prototyping area, two 12 -bit analog inputs, a real -time clock, and 32K bytes of EEPROM storage. BS2-IC module not included. BarryJones of Tech-Warrior, Inc. (Lanham, Mary- land) uses BASIC Stamps to add auto -repeat, LCD readouts, and otherfeatures to his paintball rifles.

3805 Atherton Road, 4102 Rocklin, CA 95765 USA (916) 624 -8333 Fax: 624 -8003 FaxBack: 624 -1869 BBS: 624 -7101 PAR09LLA E -mail: info @parallaxinc.com Ftp: ftp.parallaxinc.com World- wide -web: http:/ /www.parailaxinc.com

85, -IC & BST -IC are trademarks and BASIC Stamp & the Parallax logo are registered trademarks of Parallax, Inc. 0496PESR Prices do not include shipping and applicable sales tax Features and prices subject to change without notice. Prices am U.S. prices only; prices In other countries may vary. CIRCLE 156 ON FREE INFORMATION CARD

AmericanRadioHistory.Com td k

e offers All Mode onmtunications Decoding. - -L._=cl 1. i MHzH-,, TCSS. 1.03.5 Hz CTCSS Mode

461.71'3 h1Hz VTM. 800327591: DTMF Mode High Speri FM Communications Nearfield Receiver sweeps ralge of 30MHz to 23Hz in less than one DCS Mode also available second ` Two 1i e naracter LCD displays Frequency and eith All Mcde Decoding ( CTCSS., DCS. DTMF), Relative Signal Strength, Latitude anc Long_tude. or FM Deviation Additional Display Modes: with automatic backlight Latitude/Longitude Mode NMEA -0183 GPS Interface i,rovides tagging data with Signal Strength Mode Deviation Mode location for mapping applica = ions* LTR- Trunking Mode CI -V acrrpliant Serial Data Interface wi-h both TTL and RS232: I vets Frequency Recording Memory Register logs 500 frequencies with T me, Cate, Latitude, ar_d Longitude. information Real -Tim° Clock/Calender with ta_tery back -up Frequency Lack Out, Manual Skip_ and Auto or Manual Hold capabi ity INNOVATIVE PRODUCTS 'Tape Cent-of Output with Tire Recorde- Pause control relay and FOR A MODERN DTMF Encoder for audio da-a recorcing PLANET 'Rotary Encoder for easy selection of menus for setup _ Internal Speaker, Audio earphone'headp tone jack - Miniatre 8 -2in DIN Serial interface port for PC connection FIRODUCTfJRY PRICE Relative Itn segment Signal Strength Bargraph Mode

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