Popular Electronics - American Radio History

48784
SPOTLIGHT ON HOME
THEA.
Popular Electronics
AVIATION -BAND RECEIVER
10
Listen -in to rama is ra i
communications from pilots, groun
controllers, and more
BUILD A
H BITO
Give yourself and your neighbors
some peace and quiet with this
training aid that humanely curbs
your dog's barking
GERNSBACK
NAVIGATION SYSTEMS
FOR YOUR CAR
and
ED navigation systems,
Pr
satellite positioning,
roadside beacons,
and more
UNDERSTANDING
MICROPROCESSORS__
RAMSEY M NI-FECEIVER
We all know what micro-
processors do, but how many of
us understand how they work?
3
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BP122 -AUDIO AMPLIFIER CONSTRUCTION
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JANUARY 1993, VOLUME 10, NO.
1
R
Popular Eleetroles
THE MAGAZINE FOR THE ELECTRONICS ACTIVIST!
CONSTRUCTION ARTICLES
Fred Blechman
31
Gaffigan Jr
36
Michael A. Covington
43
Charles D. Rakes
45
Bill Siuru
39
Laura Quarantiello
47
Timothy D. Green
59
Larry Lisle
63
BUILD AN AVIATION RECEIVER
Join a growing throng of listening enthusiasts who tune in to the drama of aircraft communications
Robert
BUILD A DOG BARK INHIBITOR
J.
Give yourself and your neighbors some peace and quiet with this humane training aid
A TELEPHONE LINE -IN -USE INDICATOR
Keep others from barging in on your telephone conversations with a simple line- monitor circuit
BUILD A WIRE TRACER
Cut those tough home -repair and remodeling jobs down to size with this wire -tracing circuit
FEATURE ARTICLES
ON -BOARD NAVIGATION SYSTEMS FOR YOUR CAR
Satellite positioning. roadside beacons, and other new developments to help drivers stay on course
TRACKING DISTANT SIGNALS
By monitoring the VHF low-band for skip, you could easily make some wonderful long- distance contacts
ALL ABOUT MICROPROCESSORS
We explore what makes these powerful chips tick in an informative but intuitive style
THE CODE MAKERS
Trace the history of code and code -sending gear from the early days to todays computerized equipment
PRODUCT REVIEWS
GIZMO
5
Spotlight on home theater: Sharp Sharpvision LCD Projector: Carver A V Receiver; Cerwin -Vega Sensurround
Speaker Systems; and much more
22
HANDS -ON REPORT
Heath Reflex Wireless Doorbell
PRODUCT TEST REPORT
Len Feldman
26
Marc Ellis
65
Jeff Holtzman
67
Charles D. Rakes
70
John Yacono
72
Don Jensen
75
Carr
80
Marc Saxon
82
Carl Laron
2
Cannon UCI 8mm Camcorder
COLUMNS
ANTIQUE RADIO
The Sky Buddy: All together again
COMPUTER BITS
The XT syndrome
CIRCUIT CIRCUS
UJT circuits
THINK TANK
RF bulbs
DX LISTENING
Targeting the world
Joseph
HAM RADIO
J.
Some more potpourri
SCANNER SCENE
A couple of winners
DEPARTMENTS
EDITORIAL
LETTERS
FACTCARDS
POPULAR ELECTRONICS MARKET CENTER
FREE INFORMATION CARD
1992 ANNUAL INDEX
ELECTRONICS LIBRARY
NEW PRODUCTS
ELECTRONICS MARKET PLACE
ADVERTISER'S INDEX
3
49
50A
51
53
84
87
95
98
Popular Electronics (ISSN 1042-170X1 Published monthly by Gernsback Publications, Inc.. 500 -B 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. R125166280). 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 $2.95. «- 1992 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 trademark 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 -9932.
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 disclaims any
responsibility icr the safe and proper functioning of reader -built projects based upon or trcm plans or information published in this magazine.
www.americanradiohistory.com
1
PQpularElectronics
Larry Steckler
ENE CET
Editor- /n -C hie( und Publisher
EDITORIAL DEPARTMENT
Carl Laron
Editor
Robert A. Young
Ascnev,te Editor
John J. Yacono
A,ea late Editor
Byron G. Wels, K2AVB
Aasoriute lidúnr
Teri Scaduto
At.,i,tan
t
Editar
Kathy Terenzi
lidirnrial AS
vista,,;
Marc Spiwak
EDITORIAL
A MIXED BAG
Since deregulation, cable -TV companies have pretty much
had their way. In most communities, they enjoy a monopoly. If
consumers don't like the pricing structure, programming
choices, or have other complaints, they have had little
recourse except not to subscribe. And while local
governments could threaten a poorly performing cable
company with franchise revocation, such actions were
essentially impractical. The cable industry could operate as it
saw fit, and without fear.
Editorial Associate
Joseph
J. Carr, K4IPV
Marc Ellis
Len Feldman
Jeffrey K. Holtzman
Don Jensen
Chris F. O'Brian
Charles D. Rakes
Marc Saxon
Cnntrihutigg Ed, too
PRODUCTION DEPARTMENT
Ruby M. Yee
Prndurtìon Director
Karen S. Brown
Production Ai amigo'
That situation changed somewhat with the passage of the
cable -TV bill this past October. Passed over the veto of
President Bush the bill helps level the playing field a little.
Unfortunately, the key words here are "a little."
Furthermore, the bill is far from perfect. For instance, the
new bill provides some limited rate relief. It allows the FCC to
regulate only the most basic tier of programming; the FCC has
no input on other rates unless it receives complaints from
consumers, municipalities, etc.
Marcella Amoroso
Production A.uu,ttant
Lisa Rachowitz
Editorial Production
ART DEPARTMENT
Andre Duzant
Art Dirertor
lnjae Lee
uhtstrator
Russell C. Truelson
!lluitramr
Jacqueline
P.
Cheeseboro
Circulation Director
Michele Torrillo
l'-E Bookstore
BUSINESS AND EDITORIAL OFFICES
Gernsback Publications, Inc.
500 -B Bi- County Blvd.
Farmingdale. NY 11735
-516- 293 -3000
Fax: 1-516-293-3115
President: Larry Steckler
1
Customer Service /Order Entry
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7:30 AM - 8:30 PM EST
Advertising Sales offices listed on page 98
Cover photography by Denny Bailly /Unicorn Stock
Photos and Diversified Photo Services
Composition by
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AB ABC
AUDITED
2
Also important is a provision calling for cable systems to be
technically compatible with all TV's, VCR's, etc. Except where
off -premises descrambling is used (and currently few
operators use that technology), most scrambling techniques
render features such as picture -in- picture essentially useless
(unless additional descramblers are rented). Unfortunately, it is
unclear how this provision will be interpreted (perhaps it will
give life to the EIA's multiport standard ?), and it is vague
enough to give operators the leeway they need to skirt it with
little imagination.
Somewhat troubling is a provision that allows TV broadcasters
to charge cable companies for use of their signals. It ignores
the fact that broadcasters already receive value for their
signals in terms of higher viewership and, hence, higher
advertising revenues. Worse, intertwined with modified must carry regulations, it could tax the channel capacity of older,
smaller systems, or deprive viewers of channels they desire.
This provision was unnecessary, and could be a source of
trouble in the years to come.
In short, all the sound and the fury aside, the bill appears to
be a mixed bag. Its benefits will largely depend on how, and
how vigorously, the FCC chooses to implement and enforce its
provisions. But at least it's a start.
Since some of the equipment and circuitry described in
POPULAR ELECTRONICS may relate to or be covered by
U.S. patents, POPULAR ELECTRONICS disclaims any liability for the infringement of such patents by the making,
using, or selling of any such equipment or circuitry, and
suggests that anyone interested in such projects consult a
patent attorney.
Carl Laron
Editor
www.americanradiohistory.com
MUDDLED MESSAGE
LETTERS
I'm writing concerning a minor
problem with the "Personal
Message Recorder" project
(Popular Electronics, October
1992). As described on page
40, the electret microphone
must be tied to analog ground,
but according to Fig. 2 (schematic diagram) of the article,
there is no such connection.
The correct connection is
shown in Fig. 1 here. There is
0.1 -1,F capacitors have been interchanged. The part
designated Cl is actually C2,
C2 is C3, and C3 is Cl.
C.B.
Brooklyn, NY
HIGH -ENERGY, HIGH -
U1
ISD1016
RISK IGNITION
C2
1
17
MIC
R3
10K
+5V
Fig. I
also a problem with the partsplacement diagram (Fig.4). The
designations for the three
Charles Ball's article, "Build A
High- Energy Ignition System
For Your Car" (Popular Electronics, September 1992)
appears to be a good article in
general, but makes a few risky
assumptions that must be pointed out to your readers.
First, retrofitting a high-output
ignition on an older car requires
that the entire ignition system
be capable of handling all that
extra energy that the old point/
Kettering ignitions weren't intended or designed to handle.
In any ignition that has a 40kV
or higher peak output voltage,
the distributor cap, rotor, plug
wires, and plug -wire boots must
be designed with sufficient insulation and high dielectric
strength materials, to withstand
the high voltages at automotive
under-hood temperatures. To
prevent problems with ionization
and crossfire between adjacent
terminals, most late-model high energy ignitions use distributor
caps with wider spaced terminals, many are vented, and
most are made of better insulating material. The rotors are
correspondingly redesigned and
made of high dielectric strength
materials. The plug wires have
thicker, better insulation and
thicker boots (8mm plug wires
are used in the late-model ignition systems, compared to 7mm
wires with thinner boots that are
usually used on point/Kettering
systems).
On cars having OEM suppression plug wires, those wires
should be replaced after about
four years or 35,000 to 40,000
miles, as the carbon core in
them doesn't last much longer
than that. When the wires go
bad, the electricity may find a
path to ground through the insulation. You should use highquality plug wires of suppression core, wire-wound
suppression type, or (where
legal) copper-core wires made
Train at HOME to be an
Eetrocs Tchncan
As the demand for computers and microprocessors
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Choose From Five Programs of
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E193
by "hot rod" after-market ignition
makers such as Accel, Mallory,
time to rival some capacitivedischarge ignitions.
Jacobs, Moroso, or MSD. The
distributor cap and rotor should
be similarly upgraded to high quality after-market parts.
Second, Mr. Ball assumes
that higher spark energy automatically reduces emissions,
but the degree of emission reductions really depends on
many variables such as ignition
timing- advance settings, carburetor air /fuel ratio, cam -shaft
timing, etc. The air/fuel ratio
should be set with the aid of an
emission analyzer for best results.
Third, ignition energy may not
necessarily improve from the
addition of a capacitive -discharge ignition box alone if the
original coil is not up to handling
the job. Most ignition coils designed for point/Kettering or
conventional (non-capacitive
discharge) electronic ignitions
have higher inductance, especially primary winding
inductance, than coils specifically designed to give maximum
output with capacitive- discharge
(or CD) ignition boxes. To ensure maximum output you
should use a CD- compatible ignition coil with a CD ignition
unit. Those after-market ignition
coils have better insulation to
protect against internal coil
shorts at very high output voltages for which OEM coils aren't
usually designed.
Fourth, while CD ignitions
boast extremely fast voltage rise
time and high output voltage,
you must consider the impedance through which that voltage
is measured. Voltage measured
on a high secondary side impedance can be very high, but
current delivered to the plugs
will be low. Spark plugs and
wires with lower resistance or
impedance will "load" the coil's
output and lower the voltage
output measurement, but plug
current will be higher. Total energy output is voltage x
amperage x time, and many
CD ignitions produce sparks of
shorter duration than conventional point/Kettering or
electronically switched ignitions.
In fact, some conventional electronically switched ignitions with
suitable high -performance coils
can produce sparks of sufficient
voltage, current, and duration
J.M. N.
Donora, PA
A TESLA COIL ADDICT
really enjoyed the "Circuit Circus" column entitled "Fun With
Tesla Coils" (October 1992).
built the Tesla coil oscillator and
was surprised that the coil actuI
I
ally produced a significant (/inch arc) output with such a
small input signal. am currently
modifying the circuit to drive the
primary circuit of my standard
Tesla coil, with the intent of
using the solid -state circuit to
help me optimize capacitor /inductor values in my Tesla coil's
primary /secondary circuit.
Because used open construction when breadboarded
the oscillator circuit, using no
RF shielding, managed eventually to fry all my in -stock 567
chips, as well as two or three
voltage regulators. am going to
go to a 555 timer chip circuit
because that chip is more readily available at my local Radio
Shack store. You can be sure
that am also going to shield
this thing!
My biggest surprise was just
how sensitive these coils are
when it comes to setting them
to resonant frequency. They are
very, very touchy.
have been building Tesla
coils since 1965 (prompted by,
coincidentally, a Tesla-coil project in the July 1965 issue of
Popular Electronics). have yet
to build that one special "big
one" that most coil builders
dream about, although really
gave it a good try several years
ago.
That attempt was a Tesla coil
that had a primary nine feet in
diameter and a secondary 18
inches in diameter. The 52 -inch
tall coil was space wound with
over 4700 feet of 24 -gauge wire,
sprayed with 24 cans of acrylic
plastic. The primary coil was
tapped, of course, but could
also precisely tune it by a mechanical arrangement that
varied the spacing between
turns -no mean feat on a coil
the width of my garage!
The capacitor was an oil- filled
glass -plate job, which weighed
almost 700 pounds. The transformer was a 4 -kva, 300 -pound,
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oil- filled monster that had rebuilt at a local transformer
company. The transformer was
originally from a surplus ground based military radar: 18,000
volts, 220 milliamps. had to
use a 3000-watt clothes dryer
as a current limiter because the
100 -amp circuit breakers used
as "on/off" switches could not
handle the primary current of
the transformer!
All that work, time, and
money, and was never able to
achieve resonance! was more
disappointed in the failure of
that Tesla coil than was in the
failure of my first marriage! A
couple of years later, a water
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leak in a storage building ruined
very sad
the secondary
sight, indeed.
am currently trying to locate
as much "practical" information
on Tesla coil tuning, construction, etc., as possible.
Anyone who has spent any
time building Tesla coils knows
that they are addictive, and that
they can be the most challenging, frustrating, yet exciting
projects that a person can build.
think the article will help in
future Tesla-coil projects, and
encourage Popular Electronics to publish more Teslarelated articles. In fact, if you
were to start a Tesla project
construction magazine, I'd become a charter subscriber!
-a
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including a potentiometer for
adjusting the flicker rate. probably still have a few of the
lamps and other components in
my junk box.
Serving as the Electronics Officer on board the USS
Saratoga, made a flashing
symbol of an electron to hang
over my desk. First made two
loops of #12 wire with the
largest dimension being 8
inches. soldered the body of
an NE51 lamp to the loop.
soldered a capacitor in parallel
with the lamp and used the
resistor to complete the circuit
to the other loop. used #32
wire to support the loops from a
battery lying in the cables in the
overhead. It looked like it was
floating in the air and blinking at
the same time. After had it
wired and working, sprayed
the components with gold -colored spray paint, masking the
lamps first, so nobody could
see what the values of the parts
were.
R.A.N., LCDR USN, Ret.
Brunswick, GA
I
I
I
I
I
I
I
I
HAVES & NEEDS
I
I
am looking for a schematic of
a Model 700 DF-AF crystal
Irving, TX
marker/TV generator made by
the Electronic Measurements
Corporation. am also looking
for a VN1OK MOSFET transistor. Thanks.
David L. Murphy
DOWN MEMORY LANE
4948 Caribee Drive
St. Louis, MO 63628
B.P.
I
I
I
I
Reading the article, "Build the
Idiot Box" (Popular Electronics, September 1992), sent
me hunting through the attic for
a similar device that made in
1952. found it, and it still
works.
made mine with 100 lamps
mounted in shallow holes in a
square of plexiglass. It was
made to be hung like a picture
from the wall and was AC
powered. It served as a night
light and for entertainment for
two small children.
In 1952 you could buy bags of
surplus components at a very
low cost. believe purchased
200 capacitors for less than $3,
and got the same number of
10- megohm resistors for even
less. The circuit is identical to
the one shown in the article,
I
I
I
I
I
www.americanradiohistory.com
I
own a Sansui SR -838 turntable. Last year it lost speed
control and strobe. have tried
several "so-called" Sansui serI
I
vice centers in the local area for
repairs. All claim to provide
prompt and professional service
of Sansui products; however,
have had no success.
Please help me find someone
in my area that will service this
turntable. am willing to pay the
cost of shipping, if necessary,
since am not ready to trash the
turntable.
As a final alternative, I'd appreciate if someone could send
me a copy of the schematic and
parts list for the SR -838, and
will attempt to repair it myself.
I
I
I
I
Arthur Alston
1468 Key Parkway, Apt. 302
Frederick, MD 21702
(I; I 7,1t1
JANUARY 1993
VOLUME 6,
NUMBER 1
A CHRONICLE OF CONSUMER ELECTRONICS
Spotlight on
Home Theater
We have to admit that we love poring
through the glossy pages of Audio /Video
Interiors and other high -end magazines,
ogling custom A/V installations that are as
expensive as they are visually, audibly, and
aesthetically pleasing. Ten -foot screens
gracefully descend from the ceiling,
motorized panels slide back to reveal a
huge back -projection TV, speakers are recessed into the walls, touch- screen computer monitors control a dozen different A/
V "zones." One recent issue featured a
custom installation in which the equipment included 97 in -wall speakers plus
three other pairs, two amplifiers, a receiver, two tuners, a CD player, a cassette
deck, assorted remote equipment to route
the audio and video throughout the house,
four VCR's, a seven -foot front projection
TV, a 50 -inch rear-projection set, and 18
(yes, eighteen) 20 -inch TV's!
Time for a reality check: If we tried to
put all that equipment into our house,
there would be no room left for the family,
let alone furniture, clothing, and other
basic necessities. In fact, it's unlikely that
our house is worth as much as was paid for
that custom installation!
That's not to say that average people
can't incorporate some of the ideas and
technology represented in that "dream installation" in their own relatively modest
homes, keeping within their own relatively modest budgets. In this month's
Gizmo, we'll take you on a tour of home
theater-what it means, what's required,
what's optional, and how you can make it
work in your home. Then we'll take a look
at several products that you might consider
integrating into your own home -theater
setup.
The goal of any home theater, of course,
is to recreate the video and audio sensations experienced in a movie theater (or
concert hall, or sports arena, depending on
your viewing tastes) as closely as possible
in the home. Doing so requires, at the very
least, a large-screen stereo television, a
stereo VCR, some sort of surround -sound
processor, and speakers. Sounds simple
enough, right? The problem is that be-
tween that basic installation and the
custom dream job described above, there
lies a whole world of options and a wide
range of prices. Deciding what sort of
components would work best for you is no
easy task.
There are several factors to be considered before you venture out shopping and
get even more confused by fast- talking
sales people. Money, of course, is a major
concern. But "bargain" and "value" are
totally different concepts. What might be a
real deal for someone-grabbing up a
sale -priced low -end A/V receiver, or
skimping on the speakers, for instance
could ruin the whole home -theater experience for someone with more sophisticated
ears. That's not a good value at any price.
In a similar vein, you might decide to go
all out and splurge on the biggest screen
available ( "If I'm going to do it, I'll do it
right!"), only to get it home and discover
that it's much too large for comfortable
viewing in your home theater.
-
WHO, WHAT, WHEN, WHERE?
it's easy to imagine all the things you'd
like your home theater to have. But it's
importanr not only to determine what you
want from a home -theater system -but
also to make sure that your dreams are
compatible with your home, your family,
and your wallet. Ask yourself the following questons before making any purchase
decisionsc
Who is going to be using the home theater system? If you're an electronics
enthusiast, and no one else will be touching the ccntrols, then simplicity won't be a
high priority. Chances are, however, that
everyone in the family will want to use the
system. If no one can figure out how to
switch functions, there will be a lot of
gr_ef-for you as well as everyone else.
When are they going to be watching it?
Daylight conditions aversely affect front projection systems and, to a lesser extent,
rear- projection sets; a direct -view set
would be a better choice for those who
watch TV during the day, or who prefer to
keep some lights on in the room.
TURN PAGE FOR CONTENTS
This
month
in
GIZMO
Spotlight on Home Theater
pg. 5
Sharp XV-H3OU SharpVision LCD
Projector
pg. 12
Carver HR -894 AN Receiver with
pg. 14
Dolby Pro Logic
Cerwin -Vega Sensurround 7 -Piece
pg. 16
Speaker System
Toshiba CD /CDV/LD Disc Player
pg. 17
Model XR -W70A
Bose Home Theater System
pg. 20
Mitsubishi Pro -Logic Surround -Sound
pg. 20
System
Panasonic Rear Projection TV pg. 20
Zenith /Bose Surround -Sound
TV
pg. 20
Gizmo is published by Gernsback Publications, Inc., 500 -B Bi- County Blvd., Farmingdale, NY 11735. Senior Writers: Chris F
O'Brian and Teri Scaduto. Contributor to
this issue: Frank Barr, APEL. ©Copyright
1992 by Gernsback Publications, Inc.
Gizmo is a registered trademark. All rights
reserved.
Where is the system to be placed? Do
you have a room available that can be used
solely for home theater? Most of us don't
have that luxury. If the system will be set
up in the living room. there probably will
he restrictions due to decorating concerns.
If it's in the family room, keep in mind the
6
other activities carried out there-doing
homework or school projects, listening to
music, paying bills, reading the paper.
playing board games. Again, keep in mind
the lighting required for those other activities.
What size is the room? A screen that's
too small can get lost in a large room; a
screen that's too large can be even worse.
We'll discuss component, speaker, and
furniture placement later in this article.
What tirrll you be watching? Do you
prefer live performances of opera and symphonies, or action films like Terminator
II? Sporting events, or foreign films? Network sitcoms, or nature shows? All of the
above, and then some?
How can your existing components be
integrated in the new system? It's often not
necessary to buy all new gear. Use your
existing TV or hi -fi VCR and put the
money you would have spent toward a better A/V receiver; you can always upgrade
the other pieces later.
What wiringlinstallation skills do you
possess? Will you have to call in a pro to
set up your home theater, or can you handle the connections on your own? if you
decide that you need help with all or part of
the job, or with selecting the components,
you might want to consult an audio /video
installer (who should ask you some of the
same questions we are).
How much can you comfortably afford
to spend on a home -theater system? A
well -planned home -theater can provide
your family with hours of inexpensive entertainment. But if you have to take a second job to pay for it. you won't have any
time to enjoy
it'.
THE HOME -THEATER
ENVIRONMENT
Although home theaters can come in all
shapes and sizes, there are some basic
rules that should be followed, although
they aren't written in stone. Figure 1 illustrates the recommended arrangement of
furniture and components. If there are
plenty of windows, special curtains or
shades might be required to give you better
control over the room lighting. Carpeting
is recommended to minimize the reflection of sound. The minimum distance
from the couch (or recliner) to the screen
should he 2 -3 times the screen size (measured diagonally). If, for instance, your
sofa is 12 feet from the television, the ideal
screen size would be 48 -72- inches. In
general, projectors need to be placed at a
distance of about 11/2 times the diagonal
screen size. (One exception to that rule is
the SharpVision reviewed in this issue,
which requires somewhat less space between projector and screen; be sure to follow the manual's recommendations.)
Chairs and couches should be set up so
that the viewing angle doesn't exceed 30°.
Speaker placement requires the center
speaker to be as close as possible to the
screen; magnetic shielding is essential to
avoid distortion to direct -view screens.
The front speakers should be placed to
either side of, and at an equal distance
from, the screen; again, shielded speakers
will likely be required. The surround
speakers go behind the viewers -prefera-
www.americanradiohistory.com
bly the same distance behind the viewers
as the front speakers are forward, although
time -delay circuitry in a surround processor lets you mount the rear speakers
closer. A second set of surround speakers
might be necessary in very deep rooms;
they should be placed at the sides of the
room. The subwoofer can be placed anywhere in the room, and many are designed
to slide out of view under a couch or chair.
For room -shaking bass, you'll probably
want a separate amp to drive the sub woofer.
That much equipment can overtake a
small room, and push other activities to
the background. To avoid conflicts with
decor and retain the use of the family room
or living room for more than watching
movies, you might consider converting a
previously unused area of your home far
use as a home theater. A basement, attic,
or attached garage that you wouldn't consider prime living space due to lack of
windows and/or lower than normal ceilings just might be ideal for a home theater.
The natural dimness is a plus, and because
you'll spend virtually all your home -theater time seated, the only worry with low
ceilings is speaker placement. And if
you're handy with tools, finishing a previously unfinished space would also give
you the chance to create your own custom
installation.
Instead of using a separate space, it
might be possible to use the same space at
different times for different purposes.
Front- projection setups are particularly
well -suited for home theaters that must
disappear when not in use. It's often possible to mount the projector unobtrusively
on the ceiling (in custom jobs, you can
even have the projector recessed into the
ceiling on a motorized lift), and some
manufacturers offer projectors that have
been factory- mounted in coffee tables.
Ceiling -mounted screens roll up and out of
sight when not in use. Today's in -wall
speakers are almost invisible, and a sub woofer can be easily tucked out of sight.
Such a set -up allows you to use your living
room or family room for everyday activities. until it's time to "raise the curtain" on your home theater.
A friend of ours built an innovative
home -theater setup (shown in the opening
photo) in a room that measures about
14 x 22, with only one small window an
one of the short walls. He replaced that one
with an 8 -foot -wide picture window.
Flanking the window, he built floor-toceiling, 18 -inch deep shelving units; under
the window is an upholstered window
seat
feature that his wife had always
wanted. Ceiling mounted in front of the
window is a video screen. A Vidikmn
projector is mounted on the ceiling above
the couch. Assorted components -VCR,
Pioneer laserdisc player, Fosgate Pro -Log-
-a
WHAT TO LOOK FOR IN HOME -THEATER COMPONENTS
Televisions and Monitors. First, make
sure the stereo TV or monitor you
choose is the right size for your room.
Keep in mind how big that 27- incher
looked when it replaced your old 21inch set -TV's seem to shrink with time.
At the same time, you might want to
bring along a tape measure to make
sure that that huge rear-projection set
will fit through your door, and not take up
too much floor space once its in. Some
manufacturers, Mitsubishi, for one, are
now making slim -line rear -projection
sets that take up surprisingly little
space.
The overriding factor in determining
the largest screen size you should use
is how far away from it you're going to sit.
You want to see the picture, but you
don't want to be able to see all of he
elements that make up the picture. If
you sit too close to a screen-no matter
what its size-you'll start to see the h. ,.
zontal line structure of the TV picture.
(Some display devices, the Sharp LCD
projector that we review in this issue,
add their own visible structure as well.)
If you want to get that true movie theater feeling -where the screen fills a
large percentage of your field of view
you might be able to ignore the line
structure and sit closer than the recommended 4-8 times the picture height.
Usually, though, you'll have to move
back. You don't want a bigger picture,
you want a better one.
Let's look at what this means in real
numbers. A 50 -inch (diagonal) screen
has a picture height of 30 inches. (Remember: the aspect ratio of a TV screen
is 4 x 3, so the diagonal measurement is
the hypotenuse of a 3 -4 -5 triangle. If you
can remember some high -school geometry, you can calculate the picture
height once you know the diagonal
measurement.) A viewing distance of 10
feet would be required for best viewing
of the 50 -inch monitor.
Some projection sets suggest that
you can sit at 11/2 to 2 times the picture
height from the screen. They usually
have a "soft- focus" setting that exaggerates the width of the horizontal lines. If
you can afford the $20,000 price, Faroujda Laboratories has a line- doubling
system that lets you get as close as you
would to a movie -theater screen.
A laserdisc, which produces the
highest-resolution images of any consumer video device, has a horizontal
resolution of about 450 lines. Think
twice before you consider a monitor or
projector that offers less. You'll likely
see many projectors and direct -view
sets touting much higher resolution.
But the picture on a projector-front
or rear-with a horizontal resolution of
500 lines won't look the same as the one
on a direct view set with a 500 -line horizontal resolution. That's because the
contrast and brightness will vary.
For the largest picture, you'll need a
front-projection unit. For the brightest,
,
-
highest- contrast picture, you'll want a
direct -view monitor. Rear -projection
sets are a compromise between the
two. LCD projectors can't match the
three -tube projectors -yet. But if you
need huge- screen portability, they're
the only way to go.
Don't forget to listen to your display
device, too. Many sets provide good
enough sound that you might be willing
to forgo a separate audio setup. Some
provide traditional surround sound.
Others might use two- speaker "surround" systems, such as Carver's Sonic
Holography or Hughes Sound Retrieval
System.
VCR's. VHS, stereo, and hi -fi are the
three most important things to look for in
a home- theater VCR. Yes, we know that
the S -VHS format will provide better resolution. But if you can't rent tapes -and
if you don't have a S -VHS camcorder
who cares?
Do you use a VCR to watch scenes in
slow motion or to watch still pictures?
You need a four-head deck for those
special effects. Otherwise, a two -head
deck should do you fine, and merely
-
provide
a
somewhat worse picture
when you're fast-scanning over all those
commercials. Do you edit tapes? A flying erase head will help you obtain
seamless edits, and audio/video dubbing will let you add something to your
edits. Do you use a VCR extensively for
time shifting, including when you travel?
Easy but sophisticated programming
features are what you should be looking
for.
Don't forget the little things that can
make a VCR special. A 30- second skip
feature makes bypassing commercials
a breeze. Timer backup lets you laugh
at intermittent power outages. And you
might consider buying the same brand
TV/monitor and VCR, for the matching
remotes that many brands offer.
A/V Receivers. An AN receiver can
be the nerve center of your home -theater system and will provide a convenient link to your audio components.
Make sure your AN receiver provides
sufficient switching capability. You'll
want an easy way to dub audio and
video sources, and you'll want everyone
in your home to be able to use it as well.
Many people find that on-screen displays make the setup easier.
Good sound can draw you into a
movie even faster than a teriffic picture.
For most applications, Dolby Pro -Logic
capability is what you want. The added
center channel of a Pro -Logic amplifier,
and the active sound -steering circuitry,
provides a more realistic theater -like
sound.
If you must stay on a small budget,
consider a standard Dolby Surround
(not Pro -Logic) amplifier. It won't compare favorably to a Pro -Logic amplifier
in accurately placing and tracking
some of the sound, but you might well
especially since you
be happy with
it-
www.americanradiohistory.com
should be able to find one at a bargain
price these days.
If money is not an issue, you'll want
equipment that has Home THX certification. Such equipment must receive
an official OK from Lucasfilm, Ltd., the
same people who certify THX movie
theaters. In short, Home THX certification is a sort of performance guarantee.
Speakers. Speakers are arguably the
most difficult components to choose for
a home -theater system. The only feature that counts is how they sound.,That
means that only you can choose the
speakers that sound best to you. Making your decision more difficult is the
fact that speakers sound dramatically
different depending on their placement
and your home -theater acoustics. Nevertheless, there are some general
things to keep in mind as you shop.
If your home theater will use a direct view screen,' your front speakers must
be magnetically shielded. The purpose
of Pro -Logic decoding is to place
sounds accurately. Your front speakers
should be directive, so they won't muddy the directional information. The surround speakers are meant to provide
"fill" sound. They should provide wide
dispersion of the sound.
We
generally prefer using three
matched speakers for the front. If you
must scrimp, get a cheaper centerchannel speaker. You might also be
able to economize on the rear speakers. Many speaker manufacturers have
made things easier by selling complete
surround -sound speaker packages.
Laserdisc Players. For the highest -quality video and audio playback, you need
a laserdisc player. Don't forget that video quality becomes more important
with a large- screen home theater. The
relatively recent growth of large- screen
sales might be why it's taken about fifteen years for laserdiscs to catch on.
Are videodiscs for you? Since videodiscs are still difficult to rent (but generally becoming less difficult), you
might be disappointed with a player
that sits idle most of the time. But if you
like the idea of a video library-and one
that will last, presumably, forever -then
laserdiscs are tough to beat. Here are a
few things to keep in mind as you shop.
If you plan to use your home theater
for audio as well as video, a combi player -which also plays CD's-is important. Almost all videodisc players you'll
find will offer that capability. Most will
play only a single disc. Others provide a
5 -disc CD changer.
A feature we think is important is automatic side- changing. Having to get up
to flip over a disc reminds us too much
of the days of the LP! Digital effects,
available on most higher-priced units,
can add usable scan and still modes to
CLV discs. (CLV discs have longer playing times than do CAV discs, but they
require digital effects if pictures are to
be scanned.)
'
A/V RECEIVER
AND AMPLIFIER
THE HEART OF
HOME-THEATER SOUND.
LOOK FOR PRO -LOGIC
DECODING AND
AMPLE SWITCHING
CAPABILITY.
LASERDISC PLAYER
FOR THE ULTIMATE
VIDEO PLAYBACK FORMAT.
TWO -SIDED PLAYERS OFFER
THE MOST CONVENIENCE
VCR
HI -FI STEREO
SOUND A MUST.
FOUR HEADS
REQUIRED FOR GOOD
OTHER AUDIO EQUIPMENT
A GOOD HOME THEATER
ISN'T JUST FOR
VIEWING!
SLOW-MOTION AND
STILL -PICTURE
CURTAINS/DRAPES
FOR THE MOST
PLEASING PICTURE,
YOU NEED TO HAVE
CONTROL OVER
ROOM LIGHTING.
PLAYBACK.
TV/MONITOR
t
THE FOCUS OF
FRONT SPEAKERS
THE RIGHT- LEFT -
ANY HOME THEATER.
BIGGER IS BETTER,
BUT TOO BIG IS
NO GOOD. CHOOSE
BETWEEN DIRECT VIEW,
REAR PROJECTION,
OR FRONT PROJECTION.
AND CENTER-CHANNEL
SPEAKERS SHOULD
BE MATCHED FOR BEST
PERFORMANCE. THEY MUST
BE MAGNETICALLY
SHIELDED IF THEY ARE
MOUNTED NEAR
A DIRECT -VIEW SCREEN.
SUBWOOFER
YOU'LL WANT ONE
FOR ROOM-SHAKING
SOUND. A SUBWOOFER
CAN BE MOUNTED ALMOST
ANYWHERE IN THE ROOM.
YOU MAY NEED A
SEPARATE AMPLIFIER
TO DRIVE IT.
UNIVERSAL REMOTE
ESSENTIAL FOR
CONVENIENT ACCESS TO
YOUR EQUIPMENT
FROM YOUR VIEWING
LOCATION.
PREPROGRAMMED
AND LEARING REMOTES
PROJECTOR
FOR THE LARGEST
PICTURE, YOU NEED
A FRONT- PROJECTION
SYSTEM.
ARE AVAILABLE.
SURROUND SPEAKERS
FOR THE MOST
BELIEVABLE 'FILL"
SOUND MOUNT
THE SPEAKERS
AS FAR TO THE REAR
AS POSSIBLE
Shopping for a home -theater system can be intimidating if you're confused about the
basics. This illustration, which shows the principle elements of any home theater,
provides a starting point.
is surround amplifier -fit neatly on a
built -in component rack. Infinity speaker
fit n the new shelves; the center channel is
mounted inside the window seat, with
only the grille showing. The subwoofer is
mounted under the floor
heating grate
lets the bass into the room.
-a
The first time we saw the room, we
weren't aware that it doubled as a home theater. But later, watching a football game
and a few scenes from Robin Hood: Prince
of Theives, we realized that it was one of
the best setups we've ever seen. The design represents the best of both worlds-
www.americanradiohistory.com
excellent audio and video reproduction,
and comfortably attractive surroundings.
When it's not used as a home theater, the
room benefits from added light, extra storage space, improved proportions, and attractive new seating-all thanks to a
thoughtful home -theater design.
Graduate as a Fully Traîned
Electronics Professional:
want to learn about electronics,
and earn a good income with that
knowledge, then CIE is the best
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educational value you can receive.
CIE's reputation as the world
leader in home study electronics is
based solely on the success of our
graduates. And we've earned our
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with the very best electronics training.
Just ask any of the 150,000-plus
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They'll tell you success didn't come
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LEARN BY DOING.. WITH STATE OF- THE -ART EQUIPMENT AND
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CIE isn't another be-everything-toeveryone school. CIE teaches only
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courses and an A.A.S. Degree program to choose from. So, even if
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started with core lessons applicable to
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work toward your degree in stages or
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MATCH YOUR BACKGROUND.
While some of our students have a
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,y ir I,,.awo^'w.,,i,.
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www.americanradiohistory.com
1
CALL IN THE PRO'S
If u're not handy with wiring or with
tools. or if you want a system with a ceiling- mounted projector and a motorized
screen. it might be wise to call in a specialist. CEDIA, the Custom Electronic
Design & Installation Association, can
supply a list of professionals in your area
(1- 800-CEDIA30). They don't work only
for millionaires; in fact, according to a
responses to a recent CEDIA poll of its
members, the "average" job for a custom
installation company can range from $400
to $60,000. You can hire a professional to
do it all -select the components, design
the installation, hire and supervise cabinetmakers and electricians, and calibrate
the finished system. Many custom -installed home -theaters are just a small part
of whole- house, multi -zone audio -video
systems (which is a topic that we'll cover
in a future issue of Gizmo!). But you can
also hire a custom installer to consult on a
small project, and some will even come in
just to properly set up the components
you've purchased.
Look Sharp!
t
os
o
ó
w
FOOTING THE BILL
So, what can you realistically expect to
spend on a home -theater system? The
high -quality setup that we review in this
issue-Sharp LCD projector, Carver Dolby Pro -Logic A/V receiver, Cerwin -Vega
seven -piece Sensurround speaker system,
and Toshiba laserdisc player-has a total
suggested retail price of $6958.95, not
counting the screen. (We used our own
VCR and an extra amplifier to drive the
subwoofers.)
Of course, no one who shops carefully
ever pays the full suggested retail price: it
pays to shop around. Learn what features
on each component are essential, and
which are just icing.
Shopping is made that much easier if
you decide to go with a pre -packaged system that includes all or most of the required audio and video components. For
instance, Fisher's 9235AVX A/V component system includes a 27 -inch television,
a 120 -watts per channel receiver with Dolby Pro Logic, a five -disc CD changer. a
double cassette deck, and five speakers.
Also included for a suggested price of
$2199.95 is a unified remote control that
can also operate Fisher VCR's, and a lightoak-finished cabinet. Similar systems are
available from several manufacturers;
most include TV's that have a relatively
small screen size -generally. 26 or 27
inches.
At the opposite end of the pre- packaged
spectrum is JBL's Synthesis One, which
includes a front projector, a screen, a video
signal- processing equipment,
ócontroller.
multi- component
a.
loudspeakers. cross-
12
overs, equalizers, a surround -sound pro cessor. dual 18 -inch subwoofers, six am-
SHARPVISION XV -H3OU HIGH BRIGHTNESS LCD PROJECTOR. From:
Sharp Electronics Corporation, Sharp
Plaza, Mahwah, NJ 07430 -2135. Price:
$3995.
Fisher A/V Comporent System
plitiers fo- a hone -rattling total of rare
than 1401) watts, direct radiators tier music
playback, and a compression driver horn
combination for sideo playback. JBL's
aim is to provide a complete home -theater
experience that accurately reproduces
movie soundtracks, but not compromise
music listening. To that end, the syste-n
offers two modes. For home -theater use.
Synthesis is THX licensed and appror.-ed
and offers Dolby Pro Logic and tea sup plementary surround settings. Switching
to the music mode disconnects the center
and surround loudspeakers and replaces
them with components speciticaív designed for audio sound systems. -.The sag gested price, which doesn't incladc a
video source (VCR or laserdisc paver) or
installation- (which must be done professionally) i5 $47.900.
JBL Synthesis One Home- Theate
System
Whettc- you decide to go the pre.pa.kaged rou`:e, or purchase individual components, gc)al shopping skills are important.
Determine precisely what features you expect from each component, and then lc_ k
for produc:s in your price range that otter
those features. Scan the circulars flat
come in your Sunday paper and read consumer magazines. Then go out to each of
the electronics stores in your area to comparison chap.
That's just what we did, and we found
some affordable, and some interesting,
home- theater alternatives- including
(Continued on page /
www.americanradiohistory.com
a
)
Dedicated Gizmo readers might recall
our May 1991 review of the Sharp XV-100
LCD front -projection TV. To recap: The
XV -100, weighing just over 31 pounds,
had the advantages of portability and easy
set up. We put it through its paces, bringing it with us to a ski house in Vermont,
and making it the "guest of honor" at an
impromptu Super Bowl party. The large screen experience was vivid enough to
make up for a picture that, while quite
impressive for a portable projection system, left some room for improvement.
At the last Consumer Electronics Show,
demonstrations of Sharp's latest LCD
projectors suggested that some major improvements had been made in the past couple of years. We arranged to try out the XVH3OU in a home -theater setup.
Physically, the XV -H3OU somewhat resembles its predecessor. It's even easier to
carry around or store out of sight when not
in use, now that close to ten pounds have
been knocked off-the XV-H3OU weighs
only 23 pounds. At the top of the unit is a
carrying handle; an on/off button; indicators for power, temperature, and lamp replacement; and a cover that flips open to
reveal controls for the adjustment of the
projector's picture and audio. That's one
major improvement- unlike the XV-100,
the new SharpVision is equipped with its
own audio amplifier and matched stereo
speakers built in. In some installations,
those top - panel controls can be difficult to
access. But that's not a problem, since the
XV -H3OU comes with a remote control,
another convenience missing from its
predecessor. Jacks at the rear of the unit
provide audio inputs from two sources,
audio output, one S -Video and two video
inputs, and a video output. The back of the
unit also has a cooling fan; the air intake
fan is located on the side of the projector.
The XV -H3OU still uses basically the
sane LCD technology, with some refinements. The projector uses three LCD panels. a series of mirrors, a bright, metal halide bulb, and a quality lens to project
the image. One LCD is provided for each
color component of a TV picture: red,
green, and blue. The LCD panels themselves provide no color information. Thev
transmit or block the colored light that is
fed to them. The light from the metal halide bulb is separated into the red,
green, and blue components by dichroic
minors, which are special mirrors that re-
Using the pattern makes accurately focusing the projector much easier.
Our home -theater s? stem-the SharpVision Projector. a Carver A/V receiver
with Dolby Pro -Logic. Cerwin -Vega's
Sensurround speaker system, and
CIRCLE 50 ON FREE INFORMATION CARD
fleet light of one color while transmitting
all others.
Each LCD panel contains 112,320 pixels (for a total of 336,960 pixels). That
translates to a horizontal resolution of 400
lines, compared to the XV -100's 300.
In addition. the SharpVision XVH3OU's high -intensity metal -halide lamp
generates up to 800 lux of projected
brightness at a 40 -inch screen size. That
brightness level decreases slightly as the
picture size is increased. And you can do
quite a bit of increasing -the maximum
screen size is 150 inches diagonally, compared to the XV -100's 100 -inch maximum.
The XV-H3OU also offers viewers the option of using it as a rear projector
using a mirror to reflect the image to the
screen-simply by flipping the reverse image switch.
The differences between new and old
models are immediately obvious. With no
external audio source required, hookup is
even easier. All that's required is connection to a video source (laserdisc player or
VCR) via the supplied audio and video
-or
cables. While that's perfect for large screen portability, you wouldn't be happy
with the sound in a home-theater installation, where yoe'd want to connect the
projector to an A/V amplifier, surroundsound speakers, a second video source,
etc. (The projector's manual, which details various possible setups, is another
drastic improvement over the XV -100.) By
twisting the zoom lens, the screen size can
be adjusted from 25 to 150 inches, depending on the amount of space between the
projector and the screen and the size of
your room. Actually, room size isn't quite
as critical as it was with previous models,
because a close -focus lens lets you view a
150 -inch picture from just over 18 feet
away, or a 100 -inch picture from about 12
feet. And once the unit is connected and
the screen size selected, the remote control
allows you to conveniently adjust the picture without leaving your seat.
Front -projection systems do demand
darkens: viewing conditions, and Sharp
wisely s.ipplies a lighted remote control.
The buttons don't remain lighted at all
times; pressing any button or the illumination switch located on the side of the remote causes all the buttons to light for
about five seconds. The remote can be
used to control power and volume, select
the video input source, and adjust the video and audio. On- screen displays make it
easy to adjust the picture, brightness.
color, tint, sharpness, treble, bass, and
balance. The remote control also can be
used to mute the sound, and to set a sleep
timer to turn the projector off after 30, 60,
90, or 120 minutes.
We got a lot of use out of the remote
picture- adjustment capability because the
displayed image never seemed to be consistent. We found ourselves continually
ehanginz the brightness, sharpness, and
color to get a watchable picture depending
on both the room brightness and the particular movie we were watching.
Audio and video adjustments. as well as
Bnput selection, also can he done using the
stop -panel controls on the projector. The
top -panel controls include one that's missfocus- pattern disMg from the remote
play button. Pressing that button causes a
pattern ?o be displayed on the screen for
about 15 seconds, while you make adjustments wring the focus ring around the lens.
-a
www.americanradiohistory.com
a
Toshiba laserdisc player-was installed in
a room measuring just 16 x 14 feet. The
room was pretty crowded before we unpacked the screen provided by Sharp (sold
separately from the projector). On a tripod
stand. the screen stood out a couple of feet
from the wall, while the projector was set
up about a foot from the opposite wall.
That left a space of about 13 feet -too
short to use the projector to its full 150 inch picture potential. In fact, in such a
small room, we were more comfortable
with the picture size set to about 70 inches
or smaller. although the manual said that
100 inches would be fine at that distance.
The screen does make a difference in picture quality, but it simply took up to much
space. Because of that, we found ourselves
frequently watching videos on abare white
wall instead of bothering with the screen.
Watching movies on the large screen (or
on the white wall) was a treat once the
picture was adjusted properly. As with any
large projection TV, you have to be careful
not to make the image too large or you'll
see the line structure of the picture.
(Large-screen projectors are one reason
we "need" HDTV.) With the Sharp projector, you can also see the individual pixels that make up the image. The only real
complaint we had with our sample unit,
however, was that the picture brightness
was not consistent over the entire screen
there were a couple of '"hot spots" that we
found disturbing.
For everyday "background" television
viewing, we found ourselves switching
back to our 27 -inch set that happened for a
couple of reasons: First, viewing the
smaller set doesn't require a darkened
room, and we like to read the paper or do
crossword puzzles while watching. Second, most network -TV shows just don't
have enough substance to warrant such a
big picture. After all, Rosanne and Dan
Connor and family are bigger than life
even on the small screen! (And their whining is not enhanced by surround sound.
either.)
But when it came to movie -watching,
the large picture lent a whole new dimension, surrounding us with video. And,
best of all, SharpVision's bigger and better
picture is not accompanied by a bigger
price tag! We don't think that LCD projection is ready to take over the home theater market-yet. But as LCD manufacturing technology improves -and the
dramatic improvements in the last couple
of years are likely to continue- SharpVision projectors are going to be tough to
heat.
-
13
A (Pro -) Logical
Choice
CARVER HR -895 AUDIO /VIDEO RECEIVER. From: Carver Corporation, P.O.
Box 1237, Lynwood, WA 98046. Price:
$1199.95.
14
We've always maintained that the true
heart of a home- theater system is not the
video screen. Rather, it's a good audio
system that pulls a viewer into the action.
We find a small- screen system with big screen sound far more enjoyable than a
big -screen with small - screen sound. The
true heart of a home -theater sound system
is an A/V receiver, which not only provides the Dolby Pro -Logic sound that's so
important, but also serves as a command
center for video and audio equipment.
This month, in our quest for sensible home
theater, we tried Carver's HR -895 Dolby
Pro Logic AudiolVideo Receiver.
The HR-895 is Carver's first Pro -Logic
receiver. It features a five -channel surround -sound amplifier, a "learning" type
remote, and multi -room capability that allows a user in a second room to use the
amplifier to listen to a CD, for example,
while the receiver is used in the main room
to watch a videodisc.
The front -left and front -right amplifiers
provide power outputs of 110 watts per
channel. The center- channel amplifier
provides 75 watts, and two 35 -watt amplifiers provide the surround outputs.
Seven audio inputs, four composite video inputs, and three S -video inputs provide convenient switching capability.
Front -panel audio and video inputs are
provided for easy accessibility when hooking up a camcorder.
The tuner section of the HR -895 provides a total of thirty FM and AM presets.
(If you receive FM -band stations over your
cable -TV system, a separate antenna input
is available for those stations: that input
and the available stations can also be
stored in presets.) An auto -preset mode
scans through the selected hand and automatically stores received stations in the
preset memories. While it possible to let
the receiver handle the entire function automatically, we preferred to customize the
settings as they were stored. As each received station is tuned, scanning stops for
fìye seconds. During that time, you can set
the tuning mode (to mono, for example)
and set the IF bandwidth (to narrow, for
example). If you do not want to store a
particular station, pressing the tuning up
control causes it to be skipped.
If you're like us, you might have trouble
remembering more than a few preset stations. The tuner. however, includes a function that lets you set the station name so
that it is shown in the display each time the
station is tuned. Up to five alphanumeric
characters can be stored for each memory.
Stations can be tuned directly by entering
the preset number on either the remote
control or the front -panel keypad. It's also
possible to scan through the presets, or to
change stations by tuning in the conventional manner.
A Carver feature calico ACCD (for
asymmetrical charge -coupled FM detector) is provided to reduce multipath distortion. ACCD, which is switchable, is said
to be. able to transform a multipath signal
into a clear signal by separating the stereo
sum and difference signals and rejecting
up to 8O
of the distortion -filled stereo
signal. Then. "the I5 -20% of the signal
which is clean is used to accurate:y recreate the rest of the stereo signal." Because
our suburban location is not typically
plagued by multipath problems. we can
vouch for ACCD's success only by noting
that the feature seemed to quiet some noise
front marginal signals, without degrading
strong signals.
Besides the tuner, the HR -885 offers
other purely audio functions; CD player
inputs and audio tape inputs and outputs
are provided. We're thankful that Carver
also included a phono input for connecting
a turntable. Primarily intended for use
with those functions. Carver's "Sonic Holography" is also provided. The intent of
Sonic Holography is to "restore the 3dimensionallity of a live performance
through special signal -cancellation and
time -delay circuitry." It attempts to correct the problems of traditional stereo that
occur because your ears hear the output of
both stereo speakers. It works by injecting
some degree of out-of-phase right -channel
information into the left channel signal
and vice versa. Theoretically, with the
www.americanradiohistory.com
right time delay, the out -of-phase right channel information will arrive at the left
ear at the same time the signal from the
right speaker does, and the signals will
cancel. With proper speaker setup
which is very critical for the processing to
work -we found that Sonic Holography
dramatically widened the soundstage of
stereo recordings, and produced excellent
imaging. Sonic Holography is not, of
course, intended to replace Dolby Pro
Logic.
The HR -895 provides rear-panel inputs
for a laserdisc player and two VCR's. A
front -panel input is provided, primarily for
connecting a camcorder. S -video connectors are provided for the laserdisc input
and VCRI inputs and outputs. The second
set of VCR connectors provides only composite -video jacks. Why, we wondered,
did Carver provide ar S -video input for a
videodisc player, where it provides little
benefit, and not for a second VCR where
S -video can he very teneticial? Whatever
the reason, we shoulc note that the front panel inputs do provide for S- video, sa
tape dubbing between S- video -equipped
video recorders is possible, although not
necessarily conveniert.
Two tape -dubbing options are provided
on the amplifier. Pressing the TAPE VCRs
button lets you dub audio from your audio
tape deck to your VCR. (If you haven't
discovered that your hi -fì VHS VCR can
play the part of a high- quality audio recorder-with the distinct advantage of 6hour tapes -do yourself a favor and give it
a try.1 :A second, vc P -vcR2 button lets
you dub video tapes. Dubbing can be done
even while you're watching a laserdisc.
-
t
Remember. however. that the veR:
connections don't support S- video. You'll
have to use the front -panel camcorder -input jacks for that: whatever source you
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15
16
choose as the main signal source is also
output to all video and audio outputs (Unless one of the amplifier's dubbing buttons
is pressed).
Four surround -sound modes are offered. The Dolby mode is the one to use if
your source is Dolby encoded. Most recent movies you're likely to rent will have
a Dolby-encoded soundtrack: with proper
speaker placement, the results that can be
achieved at home will be at least as good as
you're likely to hear in most movie theaters. It's likely to be better, in fact, because you can adjust the level and location
of the speakers to perfectly suit your seating position.
"Hall" and "matrix" surround modes
are also provided for non -Dolby sound
sources. The hall mode adds what we perceived as time -delay and echo effects to
give a feeling of spaciousness. The matrix
mode, we assume. passively extracts the
difference between the left and right signals and feeds it to the rear speakers. Neither mode can compete with Dolby Pro
Logic (to our ears, they simply distort the
sound), but we can imagine some instances where they would prove to be
useful. A simulated stereo mode is provided to create a stereo effect from monaural sources.
The amplifier also offers four centerchannel modes that are switchable. Normally, Dolby Pro Logic requires a center channel speaker so that on- screen sounds
appear to come from the screen. A "normal" mode is provided for that. A "phantom" mode creates a center-channel effect
using just the left- and right -channel
speakers. A "wide" mode electronically
processes the front -channel audio to create
a wider soundstage: it's useful if you must
place your speakers very close together.
The center channel can also be turned off if
you wish.
The HR -895 features a clock that can
display time in either the 12- or 24 -hour
format. The clock provides sleep -timer
and program -timer capability as well. We
think that a program timer is very important in an audio system. (Some of us record more programming from the radio
than from television.) While we're happy
to see Carver provide a program timer,
which many manufacturers ignore, we're
not satisfied with the single -event capability.
Our experience with the Carver HR -895
makes us think that it could be a sensible
source of terrific home- theater sound. Its
multi -room capability will keep the video
watchers and audiophiles on speaking
terms or let you keep track of what's
happening on the screen when you can't be
there to see it. But, the funny thing is, we
didn't find ourselves leaving the room very
often when the HR-895 was doing its
thing.
Sound Decisions
SENSURROUND HOME- THEATER
SPEAKER SYSTEM. From Cervin -Vega,
555 East Easy Street, Simi Valley, CA
93065; Price: $1660.
There was a time, not long ago, when
we would base our mov e -going recisions
on sound alone. If we -_ought a film demanded the depth and drama (Lf Dolby
Surround or THX sound systems, we
would see them in a ood theater. Films
whose soundtrack we didn't consider crucial to our enj )yment would be relegated
to "let's wait until it conies out on video"
status.
Using that selection process, we decided to see The Commit:melts, a film about a
group of working -class young Dubliners
who form a soul band, at an expensive
theater on Manhattan's Upper East Side.
We certainly didn't get our 57.50's
worth -the theater's cutdated sound system didn't do justice tore film's wonderful soundtrack. and sire the music made
the movie, the whole experience was disappointing.
We finally got to he the Commitments
the way the cirector intended 'hem to
sound. No. we didn't sell out another
$7.50 each. or buy the soundtrack on CD.
We rented the film on Iaserdisc, and listened to it through Cerojo- Vega's Sensurround seven -ptiece home- theater speaker
system. connected to 3 C'rver Dolby Pro Logic AN receiver ve quickly dis-
covered what a difference the right sound
system can make!
Sensurround technology was developed
by Cerwin -Vega and Universal Studies. It
was first used in the movie Earthquake,
and with such success that its developers
were honored with an Academy Award.
That same technology is now available
for home use, in a pre -packaged seven piece system or as separate componcn:s.
The seven -piece system that we tried out is
intended for use with "big- screen" he n-.etheater setups -those using front- or re srprojection TV's. It consists of the HT-C R
shielded center-channel speaker, two
I T-100 shielded subwoofers, and foul-ifSo satellite speakers. For home theaters
centered around direct -view televisiDrs.
Cerwin -Vega recommends a five -piece
Sensurround setup that includes the same
four satellite speakers (sold for $380 a
pair) and one HT-210C "dual subwoofer/
center-channel system" ($320). That unit
integrates two 10 -inch subwoofers and
center- channel speakers into a single,
fully -shielded cabinet that doubles (or
should we say triples ?) as a pedestal for the
television or monitor. It's also possible to
use the HT-210C and a pair of HT -S6 satellites along with a pair of your own speakers, as long as the center speaker matches
the left and right ones. (The excellent manual supplied with the speakers explains
how to calibrate the system, regardless of
the configuration.)
Now that you've heard all the options
that are available, we'll get back on track
and tell ynu about the seven -piece setup
that we actually tested.
CIRCLE 52 ON FREE INFORMATION CARD
www.americanradiohistory.com
Our first reaction upon seeing the six
large boxes in which the system was
packed was that we'd be spending an entire day simply unpacking and wiring the
system. In reality, the process wasn't that
bad-and our pre -production Sensurround
arrived two weeks before the manual did!
The HT-S6 left, right, and surround
speakers feature a 61/2-inch midrange and
1 -inch polyearbonate dome tweeter. (Our
pre-production models were not shielded).
The direct -radiating speakers are housed
in bass -reflex (vented) enclosures that
measure 113/4 x 81/2 x 11 inches. Their frequency response is rated at 80 Hz -20 kHz,
± 2dB.
The HT-CTR center -channel speaker
features two 61/2-inch midrange drivers
and a 1 -inch polycarbonate dome tweeter.
The speaker system is also housed in a
bass-reflex enclosure, but not in a standard
rectangular box. Instead, the enclosure is a
trapezoid that measures about
x 83/4 x I13/4 inches. The tweeter and
port are located between, and slightly forward of, the midrange drivers. The midrange drivers are angled out from the
center. The idea is to eliminate an on -axis
hot spot for smoother, more realistic sound
that corresponds better to the on- screen
action. The frequency response of the HTCTR is rated at 80 Hz -20 kHz, ±2dB.
The HT-110 subwoofers are what really
make Sensurround work. They consist of a
10-inch driver mounted in a bass -reflex
enclosure that measures 171/2 x 13 X 241/2
inches. The HT-110 can handle inputs up
to 250 watts. Although not on our preproduction models, the HT-110 offers a
defeatable passive crossover. If you were
to use a single amplifier to drive the speakers, you would feed the left, right, and
center- channel amplifier outputs to the
subw000fer, and then feed the left, right,
and center speakers from the subwoofer's
wiring panel. The crossover switch would
be in, or on, for this setup.
We didn't get to try that wiring scheme,
but instead used the line -level subwoofer
output of our Carver A/V receiver, along
with a separate amplifier, to drive the subwoofers. The results were outstanding. If
you enjoy explosions in your home theater,
of the sort so plentiful in Terminator II,
then you won't be able to get enough of the
HT- 110's. Explosions, we must admit,
aren't our thing. Even so, the subwoofers
added tremendous enjoyment to the movie
watching experience. Trucks sounded like
real trucks. Unexpected thumps could
make us jump.
Once the setup was complete, we were
ready to give The Commitments a second
chance. We were impressed with the accuracy of the positioning of the sound.
Even more impressive, the balance of the
sound was so even that we could not pick
out the particular speaker from which a
165/s
given sound was emanating. In other
words, we quickly forgot that we were
listening to three front speakers -and
seven speakers altogether. We were spending too much time enjoying the movie.
For the truly realistic sound reproduction that we experienced, it's crucial that
the system is wired, arranged, and calibrated properly. Luckily, the manual that
accompanies the speakers goes beyond the
call of duty, explaining not just how to set
up the system, but providing a thorough
tutorial in home -theater concepts that reveals why each piece must be placed just
so. Detailed drawings depict proper wiring for each configuration. The manual
also provides the consumer with advice on
improving room acoustics and incorporating existing speakers into the system-all
in plain English.
Since we've had the Sensurround system in our living room, we've changed our
movie-selection process. Now we prefer to
watch even the epics, adventures, and music films on videotape or laserdisc in the
comfort of home -where we can realistically expect our sound system to be
significantly better than those we found in
most local theaters.
HOME-THEATER
(Continued from page
12)
46 -inch GE rear-projection TV on sale for
just $1500, a center-channel speaker from
Kenwood for $129, a Fisher A/V receiver
with Dolby Pro-Logic for $300. a Panasonic four-head hi -fi stereo VCR for
$330, and a Pioneer laserdisc player for
$400. That's $2329, and you'd just need
to add speakers and perhaps a subwoofer
to create a full -fledged home theater. A
Sony rack system caught our eye also
sale priced at $1299, it included a tuner, a
5 -disc CD changer, a 5- cassette changer,
an A/V amplifier with Dolby Pro- Logic,
and center-channel, right, left, and two
surround speakers. The same system with
a dual cassette deck cost $999. Either system would look nice next to an existing
large-screen TV, and their racks even had
two shelves conveniently available to accommodate a laserdisc player and a VCR.
The scouting around that we did took
about the time we might have spent watching a movie. If we were actually about to
buy a home -theater system, we'd be willing to spend quite a bit more time than
that. We would have auditioned the systems to get a better feel for their capabilities, and we would have pressed the
desales personnel with questions
manded to see the operating manuals to
make sure that each component offered the
functions we required. Because in home theater installations, good planning will
definitely pay off.
-
-or
www.americanradiohistory.com
Video Viewing in
the 90's
CD /CDV /LD COMBINATION DISC
PLAYER MODEL XR -W70A; from
Toshiba America Consumer Products,
Inc., 82 Totowa Road, Wayne, NI 07470;
Price: $599.
When videodisc players were first intro-
duced back in the 1970's, the format
bombed. Video cassette recorders, on the
other hand, caught on like wildfire. Considering that most people's home -video
setups at the time consisted of a small screen color TV, it's not surprising that
more folks weren't leaping at the chance to
buy the more- expensive videodisc players,
despite their superior picture and audio
quality. After all, the VCR offered consumers the ability to record television
shows as well as to watch prerecorded
movies- -and the selection of films on videocassette was far greater than those available on disc. After a few years of sluggish
sales, Philips, the inventor of the LaserVision, pulled their videodisc players off the
market, and so did most other videodisc
manufacturers.
The LaserVision format, however, was
the only videodisc format that was never
totally abandoned. Now, in the 90's, it has
finally come into its own. In a way, the
very success of the VCR, which pushed
the videodisc player out of the market in
the 70's, helped pave the way toward its
increasing acceptance today. There's no
question that the VCR changed the way we
used our television sets. After all, with all
those movies being watched at home, the
next logical step was for consumers try to
duplicate the movie - theater experience
using their home video and audio equipment. Manufacturers were quick to respond to (and inflame) that desire, introducing stereo TV's, increasingly large screen direct -view sets, rear- and front projection systems, surround -sound processors, A/V receivers, and speakers intended for use with audio and video
equipment.
As consumers became more accustomed to sophisticated home -theater
systems, a new niche was created for the
laserdisc player. After all, once you've
spent hundreds or thousands of dollars on
A/V equipment, you're going to want the
best possible source material. With good
equipment, the flaws in VCR performance
become obvious. That's why many serious
A/V enthusiasts now consider the laser disc player to be an essential ingredient in
any home -theater installation -more important, even, than a VCR. The difference
in quality is dramatic: Laserdisc players
17
TEST RESULTS-- TOSHIBA XR -W70A LASERDISC PLAYER
The video frequency response of a
laserdisc player is a measurement of
how accurately it can reproduce signals
of different frequencies. It is measured
by playing a special signal from a test
disc that contains bursts of several specific frequencies and observing the output on a waveform monitor. The
laboratory- measured frequency response of the Toshiba XR -W70A was
not what we had expected from our
subjective evaluations. At 4.2 MHz, the
response was down 3.84 dB. That's a bit
worse than we've seen from other, similar players.
The signal -to-noise ratio is a measurement of the amount of unwanted
noise on a fixed, flat -field video signal.
A red field, used in our lab tests, is usually preferred to measure the chroma
signal -to -noise ratio. AM chroma measurements indicate the strength of the
color signal, while PM chroma indicate
the purity of the color signal. The AM
chroma signal -to -noise ratio was measured at 44.8 dB, the PM signal -to -noise
ratio was measured at 36.5 dB, both
adequate, but not outstanding.
The luminance signal -to -noise measurements indicate the brightness and
de:ail that you can expect to see in recorded videos. Such measurements indicate the amount of snow that you're
likely to see in the picture. Depending
on the reference luminance level used
when making the measurement, the
luma signal -to -noise ratio was measured at 45.1 dB, which is what we
would expect. Using the S -video output
improved the luminance signal -to -noise
ratio by about 1.5 dB.
The audio section of the XR -W70A
yielded better than average performance, as indicate by the tabulated results.
In summary, the lab results seemed to
be a bit of a mixed bag. But the results
are the same as with our subjective
tests. The XR-W70A is not something
that an audio /videophile is going to rush
out and buy. But its deficiencies are
small enough that a double -blind viewing test between the XR -W70A and
some more expensive players would
end in a draw.
GRAT
A
qj!!}I
:O
TEST RESULTS -VIDEO SECTION
Frequency Response
(40.5
MHz)
0 dB
- 0.78 dB
@2.0 MHz)
( @3.58 MHz)
( @4.2 MHz)
(
-2.92
- 3.84
Signal -to -Noise Ratio
Red Field Chroma
AM
PM
44.8 dB
36.5 dB
Luminance
100 IRE
45.1 dB
TEST RESULTS
-ANALOG AUDIO SECTION
Output Level
(1
kHz)
1.53 volts (CX on), 0.52 volts (CX off)
THD
(W75% modulation)
0.76% (CX on), 0.59% (CX off)
Signal /Noise Ratio
86.4 dB (CX on), 64.1 dB (CX off)
TEST RESULTS -DIGITAL AUDIO SECTION
Output Level
(1
kHz)
2.17 volts
Signal /Noise
(De- emphasis in)
(De- emphasis out)
Channel Separation
left
right
THD fir, 0 dB
20 Hz
kHz
10 kHz
110.0 dB
110.0 dB
121.0 dB
126.9 dB
0.0031
0.0028
0.0045
1
Linearity Error
(0 dB to
-
50 dB)
-0.01
dB
Frequency Response
(20 Hz to 20 kHz)
0.
0.12
ADDITIONAL DATA
Weight
Dimension (H x W x D)
Power Requirement
Random -Access time
Scan Time (Side 1 to Side 2)
Notable Features
#j
iIiI
dB
dB
_.._.
Testing revealed a larger than expected
drop -off at higher frequencies.
18
www.americanradiohistory.com
19 pounds
514
x
181/2
x 1714 inches
31.5 Watts
2.0 seconds
5.5 seconds
Flying erase head, Digital noise reduction,
Timebase corrector, Bidirectional frame
advance, Slow motion play 1/2X and 1/40X),
Auto indexing, Real -time counter with
memory, 1- month /6 -month program timer,
Front -panel A/V jacks, Control -L editing
interface, Control -S input.
MAIL -ORDER LASERDISCS
As laserdisc players have grown in
popularity, the selection of movies and
music videos available on disc has kept
pace. Unfortunately for LD converts
who don't live in big cities on the East
and West Coasts, stores that sell laserdiscs are still few and far between, and
those that offer a decent selection of
LD's available as overnight rentals are
even more scarce.
Some entrepreneurs have seen opportunity in that situation, and mail order laserdisc shops are now flourishing. There are big companies, such as
Columbia House Laserdisc Club
(800- 538 -2233). Discount clubs include Ken Crane's in Westminster, CA
(800- 624 -3978 or 800 -626 -1768 in CA);
the LaserDisc Fan Club of Long Beach,
CIRCLE 53 ON FREE INFORMATION CARD
display twice the horizontal resolution
(more than 420 lines) of VHS VCR's, and
have the added advantage of providing
CD- quality sound.
During those years when the laserdisc
was floundering, the audio compact disc
(which was introduced a couple of years
after the LD), was making a big name for
itself. Consumers who have become familiar with the sound quality and convenience
features of the CD format now are quite
willing to consider a similar format for
video. Laserdisc players, like standard CD
players" offer quick access to "tracks"
mary videodiscs are arranged in sections
to make it easy to "fast forward "' to a
specific scene in a movie or song on a
concert video. And now that the price of
laserdisc players has dropped and virtually
all laserdisc players also play CD's, an LD/
CD player represents an economical
choice of an A/V component.
In our home- theater setup, we used a
combination disc player from Toshiba.
The Model XR -W7 ©A CD /CDV/LD Player
can play 3- and 5 -inch CD's, 5 -inch
CDV's (CD with Video discs), CDV singles, 8- and 12 -inch CD Video LD's, and
8- and 12 -mch laserdiscs. It also adds a
couple of convenience features to home movie- viewing.
The most important convenience feature is two -sided play. It's not necessary to
manually flip the discs from side I to side 2
because the player automatically positions
the pick -up carriage assembly from one
side of a disc to another. That solves the
only complaint we had with videodisc
players. (Now, if we could only get disc
maiufactwrers to end side at some place
other than the middle of a scene....)
Intro Scan is another convenience feature that lets you play the first eight sec-
-
1
onds of every laserdisc chapter or CD track
so you can find what you're looking for. (It
will automatically change to the second
side of a laserdisc.) You can program the
unit to pi w, up to 24 chapters or tracks in
any desired order; again, you can switch
back and [nth between laserdisc sides.
(Of course. there aren't too many laserdiscs that we would like to watch in random order.) A random mode lets you play
all songs on a CD in random order; on a
laserdisc with a table of contents (such as a
CD vireo laserdisc), you can play the
chapters on one side of the disc in random
order.
Another handy feature is automatically
called into play if you turn the power
switch off during playback of a laserdisc:
when you turn the player back on, it will
pick up where it left off. For dubbing CD's
onto cassette tape, a peak -search function
makes i.t a breeze to set your recording
level; it will find the peak level, and output
it for about eight seconds so you can properly set your recorder.
When you insert a disc into the XRW70A, whether it's a CD, a CDV, or a
laserdiss, the player will automatically detect what kind of disc it is-jest as any
othercc=mbi player will do. A special function, "Direct CD," tells the player that you
are goirg to be playing a CD. That not only
speeds its decision- making process, but it
turns off the video circuitry to eliminate
the possibility of interference with the audio.
An optical digital output terminal is
provided for direct connection to amplifiers and aiher equipment with digital inputs.
Both the remote control and the front
panel offer a rotary three-speed scan control. The ele: r-scan mode gives slow scan-
www.americanradiohistory.com
CA (800- 322 -2285); Laser Craze in
Boston (617- 338 -9820), Sight and
Sound in Waltham, MA (617 -894-8633).
and Brooklyn -based SEM Video Products (800- 247 -6644 or 718 -645 -1663).
Used laserdiscs are available from such
companies as Video Brokers in Washington DC (202- 328-0428) and Triton
Video in New York City (212- 243 -3610).
iraows-#zr4
...>
ping; the low -scan mode steps scanning up
to about 10 x normal; and high-scan steps
it up to 30 x normal. The scanning was
serviceable on CLV (constant linear velocity or extended -play) discs, but. of
course, couldn't compare to that for CAV
(constant angular velocity) discs.
A soft- picture function can filter some
background noise from old vintage
movies. We also found it useful to soften
the image when we were sitting too close
to a large screen.
The XR-W70A was a strong performer
that doesn't offer any surprises. It didn't
wow us with all kinds of high -tech, high end features, but it certainly did a respectable job doing what it was supposed to. If
you're a videophile who's been watching
laserdiscs since the late 1970's, then look
elsewhere for your next player. But if
you're still wondering what all the laserdisc fuss is about, why not find out by
giving the XR-W70A a try?
'Actually, it's made here -the manual just
reads like it %s'a made' in Japan
19
ELECTRONICS WISH LIST
For more information on any
product in this section, circle
the appropriate number on
the Free Information Card.
SuperFlat Rear-Projection TV
Incorporating much of the technology used in their SuperFlat direct -view TV's.
Panansonic Companv'.s (One Panasonic Way, Secaucus, NJ 07094) PTP- 51XF20
also features a new screen and lens system developed for rear-projection sets. The
51 -inch set is capable of more than 700 lines of horizontal resolution, and can
deliver more than 300 foot- lamberts of brightness for a clear picture even in
brightly lit rooms. The TV's audio specs include 20- watts -per-channel output 8
ohms. 60Hz- 15kHz, I% THD), MTS stereo with dbx noise reduction, and Dolby
Surround Sound. Other features include picture -in -picture, Artificial Intelligence
Control of image quality to maintain the proper contrast level, parental guidance
control, built-in clock and sleep timers, dual on /off timers, favorite -channel and
favorite -picture memories, and a remote that's capable of controlling most VCR's
and cable boxes and all Panasonic laserdisc players. The set is just 27- inches deep.
allowing it to fit through standard doorways. Price: 52999.95.
CIRCLE 54 ON FREE INFORMATION CARD
Small Speakers for Big Sound
Panasonic Projection TV
If you believe that speakers should be heard but not seen, setting up a home
theater can be a real challenge. Bose Corporation (The Mountain, Framingham,
MA 01701 -9168) presents an easy solution in the unobtrusive form of their
Acoustimass -7 Home - Theater Speaker System. The matched, front -channel
speaker system includes three dual -cube arrays (center, front, and right channels)
and a bass module. The magnetically shielded front -channel speakers, which
measure just 63/4x 3' x 4- inches, include hardware that allows several mounting options -wall and ceiling brackets, table stands, and floor stands. Each array
includes a pair of 21/2-inch wide -range drivers. Using a matched center speaker
ensures that sound remains balanced and consistent from channel to channel. The
bass module, which is small enough to be hidden anywhere in the room, launches
sound waves from a pair of high -performance 51/4-inch low- frequency drivers into
the room in the form of moving air masses. All connections are made through the
bass module, and built -in protection circuitry guards the system components
against excessive input levels. Price: $899.
CIRCLE 55 ON FREE INFORMATION CARD
Bose Home -Theater Speaker System
Instant Home Theater
Intended to provide better sound without complex hookups, the HTS -ICO
instant home-theater component from Mitsubishi Electronics America, Inc.
(5665 Plaza Drive, Cypress, CA 90630) delivers Dolby Pro Logic Surround
Sound as a function of normal television operation. Installation requires only one
step and does not disrupt the normal connections between the TV and VCR or
laserdisc player. Price: 5599.
CIRCLE 56 ON FREE INFORMATION CARD
Zen th'Bose Surround -Sound System
Video by Zenith, Sound by Bose
Bose Acoustimass speaker technology is also available built into several models
of Zenith (1000 Milwaukee Avenue, Glenview, IL 60025) television sets, creating
all -in -one home theaters featuring "Bose VideoStage Surround System." It might
not be Dolby Pro- Logic, but for those interested in surround -sound without the
fuss, the combination of front- channel speakers built into the TV, and two separato
rear speakers works well. The Model AB5285BG is a 52-inch rear-projection set
that features black level expansion, which expands the number of gray-to -black
shades that can be displayed, leading to greater depth and richer colors. White
compression reduces glare from bright white areas, for crisper edges of bright
images. Lumina noise reduction decreases the "noise" that often occurs whci
sharpness levels are increased, and edge enhancement circuitry eliminates fuzz
edges in individual scenes. Price: $3295.
CIRCLE 57 ON FREE INFORMATION CARD
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E trip!
,
're
0 a FREE
o
pur.,
'Mabel Clv, C11000'
.EOOOCbC0
le? Hawaii? Las Vegas? Mexico? The Bahamas? It's ip to you. Were going to send you a free
coupon for up to six days and five nights of free lodging at the destination of your choice. Now did we get your atWhere will it
tention?
Here's how it works: We sell books, and instead of advertising our program on TV (at great expense) we decided to
pass the savings along to you.
When you decide to participate in our program, well send
you a booklet of 40 coupons and a catalog listing our current
book offerings. Purchase one book and include one of the
coupons for your second book. In all, you'll get 40 books for
your $19.95 investment.
When we receive your fifth coupon, there's a bonus for you
in the form of a free membership in the Grocery Savers of America. This will entitle you to save up to $50 or more on your
monthly grocery bill. And on receipt of your 15th coupon, you
automatically get a free membership in The Great American
Traveler, entitling you to receive a 50% savings on hotels, motels and car rentals. On receipt of your 20th coupon, Bingo!
You get that big free lodging for six days and five nights at your
choice of Hawaii, Mexico, Las Vegas or the Bahamas.
You're going to be very impressed with the book selections
as well. These are not all paperbacks, but the same, high -quality volumes you see in bookstores at many times your own purchase price. Frankly, there just isn't enough room on this page
to outline all of
the details, but
don't pass this up!
Send us your name,
address and $19.95
so we can send you all
of the information, in-
Naafi
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Th. Evo
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today. MasterCharge and \\\
Visa are accepted.
r C1.AGGK Inc.
4099
Farmingdale, New York 11735
P.O. Box
Gentleman: I've enclosed $19.95 in full payment. Please send my "The
Great Two for One Give Away" booklet of 40 coupons and catalog.
Visa
MasterCard
Name
Address
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ZIP
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SignImre
(C4p coupon and mail today! Do no! send cash through the mail.)
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ar.9r
7/,IXrCO.1.13
44t_.505.
o
cluding your catalog
and 40- coupon book
Check Enclosed
iB9í
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odo
um
HEATH /REFLEX
WIRELESS
DOORBELL
CIRCLE
A quick
INFORMATION CARD
and easy way to add or replace a doorbell
of you are probably familiar with the Heath Company-or at least "Heath
kits." While Heath is no longer in the kit
market, they have launched what
they call the Reflex line of home electronics. That line of products is designed to allow the home do -ityourselfer to install automated lighting, wireless light switches, auto -shutoff lighting, or a wireless doorbell. All at
very affordable prices. This report will
focus on their SL -6153 wireless doorMost
bell.
The Device. The SL -6153 is a pre -built
unit that allows you to install a door-
22
119 ON FREE
bell anywhere without having to hook
up any wires at all. Apart from the
"doorbell button transmitter" and a
"doorbell bell receiver," a few mounting screws or some double -sided
tape (both of which are included) are
all you need to do the installation. The
$29.97 doorbell system has a maximum range of 50 feet and works for a
year on one set of batteries. That
range should provide plenty of suitable locations to place the receiver.
The transmitter, or button, is roughly
the same size as a match box, and it's
powered from a small 12 -volt battery,
which is included with the unit. The
receiver, or bell, is powered from three
"D" cells, which are not included.
The transmitter will look
attractive
mounted at any doorway, and the receiver looks much like a traditional
doorbell chime box-both units are
an off -white color.
The receiver unit offers three switch selectable sound options. There's a
traditional "ding dong" setting, a
"ding ding" setting, and a single
"ding" setting. Besides serving the purpose of user preference, the three
sound options allow you to have a
different sounding bell at each of up
to three doors. That's the main reason
why the wireless doorbell is available
in three different RF frequencies, It is
also useful in case your next-door
neighbor has the same unit.
The most obvious need for a wireless doorbell is in cases where no
doorbell exists at all. The user is then
able to quickly install an "instant"
doorbell. You may even want a wireless doorbell for your bedroom door.
Many homes will have a doorbell at
the front door only, in which case a
wireless bell could come in handy for
the side or back door.
Installation. When we first tested our
wireless doorbell-with one person
holding the bell and another holding
the button
did indeed have a
range of at least 50 feet. However,
when testing out the doorbell at its
-it
www.americanradiohistory.com
approximate installation point, we
learned the value of something men-
tioned in the installation manual:
"Don't mount the receiver or transmitter directly on a metal surface, as the
range will be drastically reduced." If
you must locate either the receiver or
transmitter on a metal surface, it's suggested that you mount it on a piece of
wood at least 1/4 -inch thick.
Our doorbell has been installed for
a couple of weeks now and is still
working perfectly. That shouldn't
sound impressive to you -after all,
two weeks isn't all that much time
but it is at the very least gratifying to
this reviewer who had something to
compare this new doorbell to; a wireless doorbell from another manufacturer. The receiver of this "other"
wireless doorbell used only two "M"
cells for power, which lasted only a
couple of days. Also, the chime on the
Heath doorbell is much louder and
realistic sounding than that other one.
Even though that other doorbell cost
ten dollars less than the Heath unit, it
was certainly no bargain.
If the Heath /Reflex SL -6153 wireless
doorbell sounds like something you
could use, or if you're interested in any
of the other Reflex products, contact
Heath (PO Box 1288, Benton Harbor, MI
49023 -1288) directly or circle No. 119
on the Free Information Card.
-
other training shows you
how to troubleshoot and
service computers like NRI!
No
NEW! 386sx120 MHz MINI
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High -resolution,
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Features 32 -bit 80386sx
CPU, 1 meg RAM, 64K ROM,
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disk dnve
NEW! 40 MEG
DIAGNOSTIC HARDWARE
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AND SOFTWARE
You install this
R.A.C.E.R. plug-in diagnostic
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irnly,
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DISCOVERY
SOFTWARE
Train with MS -DOS, GW- BASIC,
and popular Microsoft Works
applications software
card and QuickTech menu driven software, both from
Ultra -X, give you hands -on
experience with today's
professional
LAI
Complete breadboarding
system lets you design and
modify circuits, diagnose
and repair faults
DIGITAL MULTIMETER
Professional test instrument for
quick and easy measurements
DIGITAL LOGIC PROBE
Simplifies analyzing digital
circuit operation
LESSONS
Clear, illustrated texts
build your understanding
of computers step by step
walks you
through the step -by -step
assembly of a powerful 386sx computer
giving you the hands -on
system you train with and keep
experience you need to work with, troubleshoot, and service
today's most widely used computer systems. Only NRI gives you
everything you need to start a money- making career, even a
business of your own, in computer service.
No doubt about it The best way to learn to service computers is to actually
build a state -of-the-art computer from the keyboard on up. Only NRI, the
leader in career- building at-home electronics training for more than 75 years,
gives you that kind of practical, real -world computer servicing experience.
in school, on the job, anywhere shows you
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With NRI's exdusive hands-on training, you actually build and keep the
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You start by assembling and testing your computer's 101 -key "intelligent"
keyboard, move on to test the circuitry of the main logic board, install the
power supply and 1.2 meg high-density floppy disk drive, then interface your
high-resolution monitor.
What's more, you now go on to install and test a powerful 40 meg IDE
hard disk drive today's most -wanted computer peripheral induded in
your course to dramatically increase your computer's data storage capacity
while giving you lightning -quick data access. But that's not all!
-
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Professional diagnostic hardware and software makes
troubleshooting fast and accurate
Your NRI training now includes a remarkable diagnostic package that allows
you to quickly locate and correct defects in IBM XT, AT 80286/80386, and
compatible computers.
You'll use your Ultra-X QuickTech diagnostic software to test the system
RAM and such peripheral adapters as parallel printer ports, video adapters,
and floppy and hard disk drives. You'll go on to use your R.A.C.E.R. diagnostic
card, also from Ultra -X, to identify individual defective RAM chips, locate
interfacing problems, and pinpoint defective support chips.
This ingenious diagnostic package is just one more way NRI gives you the
confidence and the know-how for advancement, a new career, or a moneymaking business of your own.
No experience necessary ... NY builds lt h
With NRI, you learn at your own pace in your own home. No dassroom
pressures, no night school, no need to quit your present job until you're ready
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support of your personal NRI instructor and the NRI technical staff, always
ready to answer your questions and give you help whenever you need it.
FREE
catalog tells more. Send today!
Send today for NRI's big, free catalog that describes every aspect of NRI's
innovative computer training, as well as hands-on training in TV /video /audio
servicing, telecommunications, industrial electronics, and other high-growth,
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If the coupon is missing, write to NRI School of Electronics, McGraw -Hill
Continuing Education Center, 4401 Connecticut Avenue, NW, Washington,
DC 20008.
a registered trademark of International Business Machines Corp. QuickTech
and R.A.C.E.R. are registered trademarks of Ultra -X, Inc.
IBM is
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McGraw -Hill Continuing Education Center
4401 Connecticut Avenue, NW, Washington, DC 20008
approved under GI Bill
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MICROCOMPUTER SERVICING
Computer Programming
TV/Video /Audio Servicing
Industrial Electronics Sc Robotics
Security Electronics
Electronic Music Technology
Desktop Publishing
PC Software Engineering Using C
Telecommunications
Basic Electronics
Name
(please print)
Age
Address
City/State/Zip
Accredited Member, National Home Study Council
18-01
25
PRODUCT
TEST REPORTS
By Len Feldman
Canon UC1
8mm
Camcorder
and more camcorder enthusiasts are
More
these days turning to the
8mm format. For reasons
that remain something of a
mystery, American video
enthusiasts initially thought
that "bigger is better" and
opted for heavy, bulky, full size VHS camcorders. Lighter and smaller compact
VHS units, dubbed VHS -C,
made some inroads when
CIRCLE 120 ON FREE INFORMATION CARO
The Canon UCI compact 8mm camcorder.
26
introduced. But since recording time was limited to
a maximum of 20 minutes,
and later extended to 30
minutes, their success was
limited. The introduction of
the 8mm format solved
both the size and weight
and the recording -time
problems, offering 2 hours
of recording time (and,
more recently, 21/2 hours on
somewhat thinner tape).
Canon has been a major
proponent of the 8mm format almost since it was
standardized. That innovative company now offers
three camcorders in their
"UC" series. Of those, the
UCI, which was tested for
this report, is the least expensive, with a suggested
list price of $1499.00.
Billed as the world's lightest 8mm camcorder (at
1.28 pounds without tape,
wireless controller, and battery), the UCI features an
8 x internal -focus zoom
lens and six -layer ceramic
circuit assemblies. A detachable, full- function,
wireless remote control; an
on- screen menu system;
and a 2-page title superimposer with "shadow" letters
and battery backup (for retaining titles) are a few of its
many features. The titles are
displayed in frames using
an interlace method that
prevents the broken diagonal lines that are usually
apparent in other camcorders that use a field memory method.
Other features include a
7 -mode high -speed shutter,
a "gain -up" switch for lowlevel (2 -lux) light sensitivity, a
24 -zone evaluated white -
balance system, automatic
wind screen, and a variety
of power -supply options (including alkaline batteries).
As
is
true of many 8mm -
camcorder models, you
can set time and date so
that they may be displayed
www.americanradiohistory.com
at the beginning of a scene
or at any time you choose.
More advanced features
include "edit erase," a system for erasing up to a
minute's worth of unsatisfac-
tory recording and
returning to the starting
point of a scene that is to
be re- recorded; backlighting compensation, which
can be used when excessive background lighting
occurs behind the subject
being taped; fade -in and
fade -out; and self-timer recording, a ten -second
standby mode that allows
you to get into the picture.
Finally, if you are using a
partially recorded tape, a
blank -tape search function
allows you to locate the
end of the recorded secfion; that avoids having
long blank, unrecorded
sections on the tape.
CONTROLS
As viewed from the rear,
the left-side surface of the
unit houses power-focusing
buttons; an automatic focus on /off button; the
fade, backlight compensation, and date buttons; and
buttons associated with titling. Toward the rear of that
surface, near the electronic
viewfinder, are a counter reset button, a menu /play
button, fast- forward /record
search and rewind /record
search buttons, a select/
record review/stop button,
and an edit switch. The
function of the buttons that
have more than one purpose depends on whether
you are in the record or
play mode.
The right side panel of
the camcorder body
(again, viewed from the
rear) houses the power on/
off switch, a power -zoom
rocker switch, the start /stop
(record) switch, and a
mode select switch that
chooses camera or playback modes. A detachable
wireless controller can be
swung up (or detached) to
uncover tape return, rewind, play, fast forward,
start /stop, zoom, stop, record, still -frame, and counter
reset buttons. With the wireless controller swung out of
the way and with the hand grip section swung down,
access is gained to the
eject switch that is used to
open the cassette compartment for loading and
unloading of a cassette. As
long as a battery or power
adaptor is connected to
the camcorder, the eject
button will work even when
power is off.
The audio and video input/output terminals are
located up front, below the
camcorder's lens and built in microphone. Those terminals can be used to
playback recordings on a
TV set equipped with audio/
video inputs or to use the
camcorder to record from
another source, such as a
VCR. A battery pack or an
AC power adaptor (supplied) attaches easily to the
rear of the camcorder.
TEST RESULTS
Advanced Product Evaluation Labs (APEL)
measured the performance
of this camcorder. Using the
"gain up" function, minimum illumination required
to produce a full -amplitude
video signal was 1.9 lux,
which was slightly better
than the 2.0-lux level
claimed by Canon. White
balance, or the amount of
chrominance (color) that
appears on a neutral object when the whitebalance control is set for
optimum was 12 IRE, which
was a bit poorer than we
would have expected.
While color contamination
(color bursts appearing on
a fine black and white pattern) measured 8 IRE when
measured from the camera
TEST RESULTS -CANON UC1 8mm CAMCORDER
Specifications
Mfr's Claim
PE Measured
Minimum illumination
2.0 lux
1.9 lux
White balance
Color contamination
Horizontal resolution
Camera
Record /play cycles
Video signal -to -noise ratio
Camera
Chroma AM
Luminance
Record/play video out
Chroma AM
Luminance
Lens
Minimum focal distance
Microphone max. output
Ext. microphone sensitivity
Audio signal -to -noise ratio
Power req virements
Weight
Dimensions (H x W x D, inches)
Suggested list price
N/A
N/A
8 IRES
N/A
N/A
330 lines
240 lines
N/A
N/A
43.9 dB
39.5 dB
N/A
N/A
40.1 dB
40.3 dB
*See text
12 IRE
f/1.8,
8
x zoom
36 inches
N/A
N/A
N/A
58.3 dB
6.5 watts
2.0 lbs.*
4.9 watts
1.28 lbs.
51/2
x 3143x
$1499.00
Confirmed
35 inches
0.41 volts
3.1 mV
63/4
Confirmed
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www.americanradiohistory.com
27
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28
Signed:
output itself, that figure decreased to a more than
acceptable 2 IRE when the
test was made for the corn plete record/playback
cycle.
Color -phase accuracy
and color saturation were
just about perfect, as illustrated in the vectorscope
photo of Fig. 1, which was
taken by APEL from a red
field. There was virtually no
evidence of streaking, lag,
or image retention when
the camcorder was panned across bright light
sources.
Resolution, or the maximum number of horizontal
lines as viewed from a resolution test chart, measured
330 lines for the camera
1
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As shown in this vectorscope photo, color -phase accuracy and
color saturation were just about perfect.
output, about equal to the
best resolution obtainable
from broadcast TV When
measured via the complete
record/play cycle, however,
resolution decreased to 240
lines, or about what we
have come to expect from
standard 8mm- format camcorders.
For the camera output,
the video color (chroma
AM) signal -to-noise ratio
measured 43.9 dB, while
the signal -to -noise ratio relative to the brightness
signal (luminance) measured 39.5 dB. For the
No Florida Sales!
CIRCLE 12 ON FREE INFORMATION CARD
www.americanradiohistory.com
complete record/play cycle, those signal -to -noise
figures changed to 40.1 dB
and 40.3 dB, respectively.
The built-in microphone
delivered a maximum audio-output signal of 0.41
volts, while external-micro-
phone input sensitivity
measured 3.1 millivolts for
full audio output. Audio signal -to -noise ratio measured
a satisfactory 58.3 dB.
Additional data supplied
by APEL indicated that the
minimum focus distance for
camcorder was 35
inches in the normal mode,
and 1/8 inch in the "macro"
this
closeup mode. The camcorder consumed 6.5 watts
of power when in the record mode. With its battery
pack and wireless controller
attached, and a 120 -minute 8mm- cassette installed,
the total weight of the cam-
corder approached 2
pounds. The overall dimensions of the unit were 51/2 (H)
by
31/8
(V) by
63/8 (D)
inches.
HANDS -ON TESTS
Since so many of the
controls are of the dual function type and the unit is
so compact, learning how
to use the UC1's many features and special effects
takes a bit of time and
practice. However, it is well
Ì
worth the effort because
this very compact unit is
able to produce professional- looking video tapes that
would have required the
use of a much heavier and
bulkier camcorder just a
couple of years ago.
We should note that
those seeking better picture
resolution than is provided
by the UCI can choose
Canon's UCS1. That unit is a
slightly heavier but equally
compact model that offers
all the features of the UCI,
plus Hi -Band 8mm -video recording and several
additional features such as
a 2 -speed 10x power
zoom and a built -in
character generator with
numerous digital title functions. For those who insist
upon better sound, Canon
offers still another camcorder -the UC20, which
features hi -fi stereo and a
7 -mode high -speed shutter.
The UCS1 carries a suggested list price of $2099.00
while the UC20 has a suggested list price of
$1849.00.
However, tor the typical
camcorder user seeking a
lightweight, full featured
8mm camcorder to use for
recording vacations, family
events, and other memories, we can recommend
the Canon UCI without any
reservations. For more information on the UCI or other
Canon camcorders, contact the company directly
(Canon USA, Inc., Video Division, One Canon Plaza,
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29
Welcome
to...
SCIENCE
0BE!
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Build a»
Receiver
Aviation
AviationsmBand
Join a growing throng of listening enthusiasts who regularly tune in
commercial air -to- ground and ground-to -air aeronautic communications.
BY FRED BLECHMAN
'
like many scanner enthusiasts
and ham operators, you are interested in listening in on all the excitement manifest in aeronautic
f,
communication, but lack the equipment to pursue your interest, then perhaps the Aviation Receiver described
in this article is for you. The Aviation
Receiver, designed to tune the
118-135 -MHz band, features exceptional sensitivity, image rejection, signal -to -noise ratio, and stability. The
receiver is ideally suited to listening in
on ground and air communications
associated with commercial airlines
and general aviation.
Powered from a 9 -volt transistor-radio battery, it can be taken along with
you to local airports so that you won't
miss a moment of the action. And
even if you're nowhere near an airport, this little receiver will pick -up the
air -to- ground and ground -to -air communications of any plane or ground
facility within about 100 miles!
Circuit Description. Figure
1
shows
a schematic diagram of the Aviation
Receiver
superhetrodyned AM
-a
(amplitude modulated) unit built
around four IC's: an NE602 double balanced mixer (U1), an MC1350 linear IF amplifier (U2), an LM324 quad
op -amp (U3), and an LM386 audio
amplifier (U4).
In operation, an antenna that plugs
into J1 picks up the AM signal. That
signal is then coupled through C1 to a
three -section, tuned -filter network,
L1 -L5 and C2-C6. Signals in the 118 -135 -MHz VHF (very high
consisting of
frequency) range are coupled
through C7 to a VHF transistor (Q1),
where the signals are amplified. From
there, the signals are fed through C8
to the input of U1 (the NE602 double balanced mixer), which in this application serves as a local oscillator. A
variable inductor (L6) and its associated capacitor network set the local oscillator frequency at 10.7 -MHz higher than the incoming 118 -135 -MHz
signals. A tuning network, consisting of
varactor diode D1 and potentiometer
R1, allows the local- oscillator frequency to be tuned across about 15 MHz.
The 10.7 -MHz difference between
the received signal and the local -oscillator frequency (i.e., the intermediate frequency or IF) is output at pin 4
of U1 to a 10.7 -MHz ceramic filter (FILI).
The filter is used to ensure a narrow
pass band and sharp signal selectivity.
The output of FILI
is amplified by Q2
and then fed through C16 to U2 (an
MC1350 IF amplifier), which, as configured, also offers automatic gain
control (AGC), as we'll see shortly. The
amplified 10.7 -MHz IF signal is peaked
using variable transformer T1. The AM
audio is then demodulated by diode
D2. After that, the audio is fed in sequence through the four sections of
U3 (an LM324 quad op -amp).
Note that a portion of U3 -a's output
signal is fed back through resistor R25
to the AGC- control input of U2 at pin 5.
www.americanradiohistory.com
is used to automatically
decrease the gain of U2 when strong
signals are present or to automatically
increase U2's gain for weak signals.
That keeps the output volume of the
circuit within a comfortable listening
range regardless of the strength of the
incoming signals.
The receiver circuit also contains a
squelch circuit that is controlled by
potentiometer R3, which is used to kill
random noise below a selected
threshold level. When properly set, the
squelch control virtually eliminates
background noise, so that all you hear
are incoming signals that can be
brought up to a usable level. Potentiometer R2 controls the overall volume
fed through C26 to U4, an LM386 low voltage audio-power amplifier. Due
to the overall design and squelch
control, the audio output is quite low
in background noise, and yet it's capable of driving simple communications speakers or earphones to
excellent volume levels.
That signal
Construction. The Aviation Receiver
was assembled on a printed- circuit
board, measuring about 4 x
43/4
inches. Figure 2 shows a full -size tem-
plate of that printed- circuit board's
layout. A kit of parts (which includes
an etched and pre -drilled, printed circuit board, but no case) is offered
by the supplier listed in the Parts List.
Although most of the parts for this
project are commonly available
through conventional electronic-
31
R7
R11
1K
1K
R5
1K
_L
R4
C8
47K
001
-I(
; R28
C16
.001
S1
C18_
C31
27052
220
10
01
v
R10
1MEG
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02
2N3904
i
I(
C17
2 MC1350
O1
R6
01
2SC2570
270e
NE802
3
01
r
1
Z
U2
8
l
D2
;
1N270
1
C7
C6
C9
.001
82pF
.01
RO
10K
+
C14
10.7MHz
10
A
+ 9V
'AR9
P.
BB405
C2
82pF
47K
%1
+
ANTENNA
10
1
C26
C27
R18
1/4
LM324
12
4
U3-a
14
1/4
LM324
11
R15
47K
LM324
1/4
+
7
+
U3-b
13
D3
LM324
1,1+
1K
1N914
I+
C29
1
1/4
10
220
t
R19
100K
I
+
+5
J2
SPEAKER
=
+ 9V
)
W.
+ 9V
C21
10
47K
10
2T
.01
R17
10K
.V.
R21
C15
J1
R16
47K
I(
R22
33K
+ 9V
=
BB505
C30
1
1
10K
TUNING
OR
L1
=
C23
C24
D1
L2
1M
R25
1K
R1
.33pH
Cl
.001
R12
10K
.01
1t H
L3
21
3.9pF
T1
C11
-r
27pF
C3
t
C20
K
3.9pF
104
C19..-.
C12
27pF
C4
82pF
C5
Ca
.01
C13
.001
L5
2T
L4
R26
22K
6
6
3
I(
.33pH
¡
9V
FILI
10.7MHz
C22
.47
+9V
R23
10K
5
6
1
41
R14
R20
47K
220
1
MEG
R27
C28
1K
.01
R24
47K
R3
C25
10
10K
SQUELCH
R2
10K
VOLUME
R13
33K
-a
Fig. 1. The Aviation Receiver
superheterodyne unit, built around four IC's-is
designed to receive AM signals in the 118-135 -MHz frequency range.
All of the components for the Aviation
Receiver (including the 9-volt transistorradio battery that powers the circuit)
mount on a single printed- circuit board.
components suppliers, a source for
some of the more difficult to find parts
given in the Parts List for those who
prefer to do their own shopping. If you
opt to gather your own parts or you
is
32
plan to use what you have on hand,
keep in mind that the circuit-board
layout was designed to accommodate components of specific dimensions in some cases; jacks J1 and J2,
switch S1, transformer T1, and all three
potentiometers, for example. To ease
the pain of obtaining those parts, a
"Special Parts lit" is also available
from the listed source.
Also note that either of the Siemens
parts specified in the Parts List for
varactor diode DI will work, but both
may be difficult to find from hobbyist
sources. However, the second unit
(BB505) is available from Allied Electronics.
However you go about collecting
the parts for this project, don't even
think about building the receiver cir-
cuit without the printed- circuit board.
www.americanradiohistory.com
At the frequencies involved, the
placement of every wire and part,
and every part value is critical for trouble-free performance.
Once you've obtained all of the
components and the board for the
Aviation Receiver, construction can
begin. A parts- placement diagram is
shown in Fig. 3. When assembling the
project, take special care that polarity- sensitive components (electrolytic
capacitors, diodes, and transistors)
are installed properly. Just one part
installed backwards can cause grievous harm!
Begin by installing the passive components (jumper wires, resistors, capacitors, and inductors). Follow that
by installing the active components;
diodes, transistors, and IC's. Once the
active components have been in-
consider the enclosure that will house
your receiver.
The receiver's circuit board can be
housed in any enclosure that you
choose. However, if you prefer, an optional case and knob kit for the receiver is available from the supplier
listed in the Parts List. The optional
case is supplied with neatly lettered
front and rear panels, knobs, rubber
feet, and mounting screws.
If you choose a case other than the
one available from the listed supplier,
it will be necessary to drill holes in the
front and rear panels of the enclosure
to accommodate the controls (S1, R1,
R2, R3) and the jacks Wand J2). Once
drilled, the front and rear panels of the
enclosure can be labeled using dry transfer lettering.
The antenna for the Aviation Receiver can be as simple as a 21 -inch
length of wire, or you can get a fancy
roof -mounted aviation antenna. If
you are near an airport, you'll get
plenty of on-the-air action from the
wire antenna, but if you're more than
a few miles away, a decent roof mount antenna offers a big improvement.
I
Alignment and Adjustment.
4 INCHES
fig. 2. Here's a full -size printed- circuit pattern for the Aviation Receiver. The printed circuit board can be purchased as part of a full-blown kit or separately from the
supplier listed in the Parts List.
Aligning the Aviation Receiver consists
of nothing more than adjusting the
slug in the local-oscillator coil (L6) for
the center of the desired tuning
range, and peaking the IF transformer
(T1). The receiver can be calabrated
using a VHF RF signal generator, frequency counter, or another VHF receiver by setting R1 to its mid -position;
remember that you want to set the
local- oscillator frequency 10.7 -MHz
higher than the desired signal or
range to be received. Then, using a
metnon -metallic alignment tool
-a
al tool of any kind will drastically de-
tune the coil, making alignment
almost impossible- adjust L6 (the LO
coil) until you hear aircraft or airport
The Aviation Recei'ver's printed-circuit board fits neatly into this optional 5- x á.25x 1.5 -inch custom cabinet (which comes with knobs, hardware, silk -screened front
and back panels, as well as rubber mounting feet).
stalled, check your work for the usual
construction errors: cold solder joints,
misplaced or misoriented compo-
nents, solder bridges, etc. Once
you've determined that the circuit has
been correctly assembled, it's time to
www.americanradiohistory.com
communications.
Once you are receiving aircraft or
airport frequencies, adjust T1 for the
best reception. Typically, T1 is adjusted
2 -3 turns from the top of the shield
can. If you don't have any signal- reference equipment for alignment, and
are not yet hearing airplanes, your
best bet is to pack up the receiver and
the necessary alignment tools, and
head for the nearest airport! If the air port has no control tower, visit a gen-
33
WHAT YOU CAN EXPECT TO HEAR
No matter where you live, you will be
able to receive at least the airborne side
of many air-traffic communications. If
you know where to tune, you can hear
any aircraft that you can see, plus planes a hundred miles away and more,
since VHF signals travel "line of sight."
An airliner at an altitude of 35,000 feet
and in the next state is probably still
line -of -sight to your antenna.
Similarly, whatever ground stations
you may hear are also determined by
the line -of -sight character of VHF communication. If there are no major obstacles (tall buildings, hills, etc.) between
your antenna and an airport, you'll be
able to hear both sides of many kinds of
aviation communication. Be prepared
for them to be fast and to the point, and
for the same airplane to move to several
different frequencies in the span of a few
minutes!
At most metropolitan airports, pilots
communicate with the FAA on a "Clearance Delivery" frequency to obtain approval or clearance of the intended
flight plan, which is done before contacting ground control for taxi instructions.
From the control tower, ground movements on ramps and taxiways are handled on the Ground Control Frequency,
while runway and in-flight maneuvers
near the airport (takeoffs, local- traffic
patterns, final approaches, and landings) are on the Tower Frequency. ATIS,
or "Automatic Terminal Information System," is a repeated broadcast about
basic weather information, runways in
use, and any special information such
as closed taxiways or runways. Such a
broadcast offers an excellent steady
signal source for initial adjustment of
your receiver, if you are close enough to
the airport to receive ATIS.
Approach Control and Departure
Control are air-traffic radar controllers
that coordinate all flight operations in
the vicinity of busy metropolitan- airport
areas. When you hear a pilot talking with
"Jacksonville Center" or "Indianapolis
Center," these are regional ATC (Air Traf-
fic Control) centers. The aircraft is really
en route on a flight, rather than just leaving or approaching a destination. A pilot
will be in touch with several different
Regional Centers" during a cross -country flight.
Airports without control towers rely on
the local Unicorn frequency for strictly
advisory communications between pilots and ground personnel, such as fuel
service operators. The people on the
ground can advise the pilot what they
know about incoming or outgoing aircraft, but the pilot remains responsible
for landing and takeoff decisions. Typical Unicorn frequencies are 122.8 and
123.0 MHz.
The FAA's network of FSS (Flight Service Stations) keeps track of flight
plans, provides weather briefings and
other services to pilots. Some advisory
radio communication takes place between pilots and a regional FSS. If there
is an FSS in your local area, but no airport control towers, the FSS radio frequency will stay interesting.
PARTS LIST FOR THE AVIATION RECEIVER
SEMICONDUCTORS
Ut -NE602 double- balanced mixer,
integrated circuit (Digi -Key)
U2-MC1350 linear IF amplifier,
integrated circuit (Allied 858 -3011)
U3-LM324 quad op -amp, integrated
circuit (Digi -Key)
U4 -LM386 low- voltage audio -power
amplifier, integrated circuit (DigiKey)
Q1- 2SC2570 or 2N5179 NPN UHF
transistor (Allied 858 -1041)
Q2- 2N3904 general -purpose NPN
silicon transistor (Digi -Key)
Dl -BB405 or BB505 varactor diode
(Siemens, Allied 586-0610)
D2- 1N270, 1N34, or similar
germanium diode
D3 -1N914 silicon diode
RESISTORS
(All fixed resistors are %a-watt, 5%
units.)
RI-R3-10,000-ohm PC-mount
potentiometer
R4, R9, R15, R16, R20, R21, R2447,000-ohm
R5, R7, Rll, R18, R25, R27,1000ohm
R6, R28-270-ohm
R8, R12, R17, R23-10,000-ohm
R10, R14-I-megohm
R13, R22-33,000-ohm
R19-100,000-ohm
R26-22,000-ohm
CAPACITORS
Cl, C7, C8, C13,
C16-0.001 -RF
ceramic -disc
C2, C4, C6-82 -pF, ceramic-disc
C3, C5-3,9 -pF, ceramic -disc
C9, C17, C19, C20, C28, C300.01-µF, ceramic -disc
C10, C15, C21, C25, C26, C31 --4.7to 10-11F, 16 -WVDC, electrolytic
C11- 10 -pF, ceramic -disc
C12, C14- 27 -pF, NPO ceramic -disc
C18, C27, C29 -100- to 220 -1.LF, 16WVDC, electrolytic
C22- 0.47 -pF, 16-WVDC,
electrolytic
C23, C24 0.1 -pF, ceramic -disc
INDUCTORS
LI, L3, L5 -I1/2-turns #24 to #30
gauge wire
L2, LA 0.33 -11H, inductor (DigiKey M9R33 -ND)
L6-0,1 -pH, 3Y2 -turn, slug -tuned
coil (Digi -Key TK2816)
T1 -10.7 -MHz, shielded transformer
(Mouser 42IF123)
ADDITIONAL PARTS AND
MATERIALS
FL1- 10,7 -MHz ceramic filter (Digi-
34
www.americanradiohistory.com
Key TK- 2306)
-SPST switch, PC mount
JI-RCA jack, PC mount
S1
J2-Subminiature phone jack, PC
mount
-9 -volt transistor-radio battery
B1
Perfboard materials, enclosure, AC
molded power plug with line cord,
battery(s), battery holder and
connector, wire, solder, hardware,
etc.
Note. The following items are
available from Ramsey Electronics,
Inc., 793 Canning Parkway, Victor,
NY 14564; Tel. 716-924 -4560: A
complete kit of parts (AR 1BP),
including printed -circuit board (but
not the case or control knobs),
$24.95; an etched and drilled
printed-circuit board only
(AR- IPCBP), $10.00; a Special
Parts Kit (AR- ISPKBP) containing
all semiconductors, R1 -R3, all
inductors, SI, Jl and J2, and FILI,
$14.50; Custom case and knob set
(C -AR IBP), $12.95. Please add
$3 for orders under $20. All orders
are subject to a $3.75 postage/
handling charge. New York State
residents, please add appropriate
sales tax.
n
n
n
PILOT AND CONTROLLER
TALK
R1
Don't blame the Aviation Receiver if all
you hear are short bursts of words that
don't make a lot of sense at first. Aviation communication is necessarily
quick and brief, but clear and full of
meaning. Generally, pilots repeat exactly what they hear from a controller, so
that both know the message or instructions were correctly interpreted. If you
are listening in, it's hard to track everything said from a cockpit, particularly in
big city areas. Just to taxi, takeoff, and
fly a few miles, a pilot may talk with 6 or 8
different air -traffic- control operations
within a few minutes, all on different frequencies.
Here's the meaning of just a few typical communications:
"Miami Center, Delta 545 heavy out of
three -zero for two -five." Delta Flight 545
acknowledges Miami Center's clearance to descend from 30,000 feet to
25,000 feet. The word "heavy" means
that the plane is a jumbo jet, perhaps a
747, DC -10, or L-1011.
"Seneca 432 lima cleared to outer
marker. Contact tower 118.7." The local
Approach Control is saying that the
Piper Seneca with the N- number, or "tail
number" ending in "432L" is cleared to
continue flying an instrument approach
to the outer marker (a precision radio
beacon located near the airport), and
should immediately call the airport radio control tower on 118.7 MHz. That
message also implies that the controller
does not expect to talk again with that
aircraft.
"Cessna 723, squawk 6750, climb
and maintain five thousand." A controller is telling the Cessna pilot to set the
I
--R6-
J
-C9-
-C20-
-CB-
-R25U2
I
-024-
R15
R22I
+
021
R13 R14
1
_-J-_-
-R21-
I
+C31
C19
-C17-
-R26-
-C7-C6-
-R12-030-
I
Ti
L4
02
L5
I
C26+
C4
-v-
-05-C3-L3-
-L2-
-C1-
I
C2
+ C27
U4
R27
I
1
J1
ANTENNA
Fig. 3. Use this parts -placement diagram as a guide when assembling the printedcircuit board
eral aviation service center on the
airport grounds, and ask which are
the most active frequencies. Then adjust L6 and R1 until you hear the action.
A ground -service operator or private pilot may be willing to give you a
brief test transmission on the 122.8 Unicorn frequency. Remember, also, that
if your airport has ATIS transmissions,
you can get a steady test signal as
soon as you are within line -of -sight of
its antenna. (See the sidebar for explanation of Unicorn and ATIS,)
Use. Plug an antenna into J1 and a 4to 8 -ohm speaker or earphone into
J2. Turn on the Aviation Receiver by
closing S1. You may or may not hear
background noise. Turn R2 (the SQUELCH
control) fully counterclockwise. Then
rotate R2 clockwise until you hear a
"pop" and some background noise;
then back it off slightly (counterclockwise) past the pop. You are now in
squelch mode.
With pilots and controllers talking so
briefly, you will need to get used to
tuning your receiver. As you sweep
across the band (via R1), listen for a
sound, then rock back and forth
slightly to tune it in clearly.
Troubleshooting Suggestions.
If
the receiver does not work at all, carefully check the obvious things first; battery polarity, soldering of the battery
wires and switch, and the connections
to the speaker jack. Also, be sure to
check that you've correctly installed
all of the jumpers. If the circuit's operation is erratic, a solder connection is
usually the culprit, or there could be a
break in the antenna or speaker wire.
Pay special attention to the orienta-
www.americanradiohistory.com
airplane's radar transponder to code
"6750," climb to and level off at the altitude of "5000 feet."
"United 330, traffic at 9 o'clock, 4
miles, altitude unknown." The controller
alerts the United Airlines flight of radar
contact with some other aircraft off to
the pilots left at a "9 o'clock" position.
Since the unknown plane's altitude is
also unknown, both controller and pilot
realize that it is a smaller private plane
not equipped with altitude- reporting
equipment.
tion of all IC's, transistors, diodes, and
electrolytic capacitors. Also, be sure
that C11 and C12 in U1's oscillator circuit are of the right values. Local -oscillator operation can be verified with
a simple VHF receiver or frequency
counter. Remember that the local oscillator should be set to a frequency
10.7 MHz above the desired listening
range. If the oscillator works, only a
defective or incorrectly installed part
can prevent the rest of the receiver
circuit from functioning.
35
Although it may seem quite
distant now, summer is approaching with the antic-
ipation of backyard games, barbecues, and the dog next door
barking incessantly. If you happen
to be the owner of the irritating,
barking dog next door, then neighborhood harmony is at risk. But,
worry not... for in this article, we're
going to show you how to build a
Dog Bark Inhibitor that will restore
neighborhood harmony by humanely stopping your dog from
barking.
Commercially available dog
bark inhibitors (electronic devices
built into a dog's collar) that are
currently on the market are both
expensive and can in some circles
be considered inhumane. With
such devices, every time the dog
barks an electrical charge is sent
to the dog's neck. While that stops
the dog from barking, it can also
turn a dog into a cowering animal
afraid of its own shadow.
However, the Dog Bark Inhibitor
described here is inexpensive and
humanely stops the dog from barking by actuating a buzzer every time
the barking begins. The buzzing is
used to give the dog negative feedback that he'll associate with his barking, causing him to refrain from that
annoying tendency.
Circuit Description. Figure
ch
co
1 shows
a schematic diagram of the Dog Bark
Inhibitor. At power up, a one -shot multivibrator, consisting of one -third of a
40106 hex Schmitt trigger (U4 -c and
U4 -d), resets U2 and U3, keeping the
buzzer (BZ1) cut off. At the same time,
resistors R1 and R2 set the trigger level
of U1 -a, U1 -c, and U1 -d (3/4 of an LP324
quad op -amp) to 2.5 volts. Op -amps
U1 -a and U1 -d are configured as inverting comparators with hysteresis,
while U1 -c is configured as a voltage
follower.
The voltage follower (U1 -c) provides
a standing DC bias voltage for an
electret microphone (MICI). When
19,
36
MIC1 picks up the dog's barking (see
the waveform diagram in Fig. 2A), the
bias voltage applied to MICI fluctuates, and the output of U1 -c follows.
Fluctuations in the microphone's bias
voltage are applied to W -d, which
amplifies the signal and feeds its out put to W -a. The overall sensitivity of
Build a
filter. The purpose of U2 and U3 -a
Dog -Bark
Inhibitor
Give yourself and your
neighbors some peace
and quiet with this
training aid
BY ROBERT J. GAFFIGAN JR.
the circuit is determined by the gains
provided by U1 -a and U1 -d. The hysteresis provided by those two op-
amps helps to keep background
noise out of the signal applied to U1 -b,
which is setup as a low-pass filter. That
low -pass filter is used to remove frequencies from the signal that are not
in the range of a dog's bark.
From the filter, the signal (see Fig. 2B)
is made compatible with digital circuitry by U4 -a (14 of a 40106 hex inverting Schmitt trigger), which also inverts
the input signal. That signal is again
inverted by U4 -f and output to the following circuitry as a train of negative going pulses. Those pulses are produced each time that the sound
picked up by the microphone falls
within the low -pass range of the filter
(see the waveform in Fig. 2C).
The output of U4 -f divides along two
signal paths: in one path, the signal is
fed to the clock input of U2 (a 404012 stage ripple carry binary counter); in
the other path, the signal is applied to
the trigger input of U3 -a (1/2 of a 556
dual oscillator /timer). The negative
pulses trigger U3 -a, whose output, in
turn, enables U2, causing it to count
the number of times that the sound
falls within the low -pass range of the
www.americanradiohistory.com
is to reject spurious sounds that
fall within the filter's range and to
allow the dog a period of free
barking.
If the counter (U2) counts 256
bark pulses within eight seconds,
its output goes high. That high is
inverted by U4 -b and applied to
the trigger input of U3 -b at pin 8,
forcing its output at pin 9 high.
The high output of U3 -b is applied
to the base of Q1 (an MPSA12
Darlington transistor), causing it to
conduct. With Q1 conducting, BZ1
(a 6 -volt electronic buzzer) activates for about half a second. At
the same time, the ripple counter
(U2) is reset via an OR gate, made
up of D1, D2, and R11.
If, on the other hand, U2 counts
fewer than 256 pulses within that
8- second period, the counter resets, and awaits the next barking
session.
The circuit
is powered by a 9volt transistor -radio battery. Because of that, the semiconductors used for this circuit were
chosen for their low- current requirements-the circuit draws approximately 0.9 microamps of quiescent current, and 15 mA with the
buzzer on and should not be substituted unless swapped for lower power components.
Construction. Although the author's
prototype was built on a section of
perfboard, using point -to -point wiring
to interconnect the circuit elements,
the final version was assembled on a
printed- circuit board, measuring
about 3 x
2 inches. A template of the
printed- circuit layout is shown in Fig. 3.
You can etch your own printed- circuit
board from the template shown in Fig.
3, or you can order a printed- circuit
board and the parts (separately) to
populate it from the supplier listed in
the Parts List.
Once you have obtained the
board and the parts that go with it,
construction can begin. Figure 4
shows the parts- placement diagram
for the author's printed- circuit layout. It
is recommended that IC sockets be
provided for all of the DIP units (U1 U4).
The regulator, U5,
is housed in a TO -92
style package. Begin construction by
installing the DIP sockets and the
jumper wires. Once that is done, install
-1R5
MICI
R12
10K
1/4
1/4
R3
1K
R6
2.2K
+5V
R7
R8
11K
11K
SOUND
LP324N
U1 b
+
U1-a
3
+
.047
LP324N
R10
56K
75K
4A'S2
C2
t
R9
39K
1/4
-^
LP324N
C5
C4
.01
.01
C3
)1-
.1
+ 5V
4
R1
100K
10
U11c
+.r
1/4
9
LP324N
U3-b
L660
-
3
8
Zti
1/2
13
12
100K
+5V
BZ1
CLK
U4-e
U2
11
R2
+ 5V
1
+5V.16
8
R16
100K
#
f
R15
1MEG
10
1/e
4
4040
RST
U4-b
40100
U4-f
'/e 40106
'/e 40100
1
08
Za
1/e
40100 14
la
11
D2
I
10
7
1N914
13
"C8
O
-
R11
100K
114
5
U3 -a
/2 ossa
4
rv.
D1
+ 5V
7
,
1N914
SOUND
1
+ 5V
2
R13
1MEG
1
C6
1/e
S1
40106
5
6
82
U4-d
1/e 40106
U4-c
R14
1MEG
8
MN
+ 5V
SOURCE
+
+5V
C7
"1
an
Fig. 1. The Dog Bark Inhibitor is comprised of an LP324 quad op -amp (UI), a 4040 12 -stage ripple carry binary counter (U2),
voltage
lowdropout,
5
-volt
series,
LM2931A
an
(U4),
trigger
Schmitt
hex
inverting
CD40106
(U3),
a
LM556 dual oscillator /timer
a
regulator (U5), an MPSA12 Darlington transistor (QI), two 1N914 general -purpose, small- signal silicon diodes (DI and D2) and
handful of additional components.
RF1
GND
(MICI) was mounted directly to the
t
A
PIN 14 U1 -d
I
-.4.j+:'
'i''
1
I
II1II-III
i/riiliiri
hfl
B
PIN 7 U1 -b
CH1
GND
C
T
CH2
GND
i
1
PIN 12 U4 -f
i
Fig. 2. Shown in A is the waveform produced at the output of U1 -d when the dog
barks; B shows the same waveform after it has undergone filtering; and C shows how
the waveform looks after being processed for application to the digital circuitry that
follows.
the passive components (resistors
and capacitors).
Aller the passive components have
been installed, mount the active
components (excluding the DIP IC's,
they will be installed in their respective
sockets later), and connect a 9 -volt
battery connector to the appropriate
points on the board. In the author's
prototype unit, the microphone
www.americanradiohistory.com
circuit board, although it might appear otherwise in the parts- placement diagram.
It will be necessary to prepare the
enclosure that is to house the circuit
board and the off -board components. The author's unit was housed in
a plastic project box with a metal lid,
measuring about 31/4 x 21/8 x 1
inches. Begin preparing the enclosure by first placing the circuit
board into the enclosure to determine where the microphone will be
located when
it
is
permanently
mounted. Mark that position on the
wall of the enclosure, and drill several
tiny holes at that location.
Next, on the same side of the enclosure, drill Iwo holes (one near each
end), which will be used to mount a
nylon web strap (dog collar) to the
project box. Then make two cutouts at
opposite ends of the enclosure for the
buzzer (BZ1) and the slide switch (S1);
the cutouts should be approximately
7/8 X 5/8 inches for the buzzer, and the
37
PARTS LIST FOR THE
DOG BARK INHIBITOR
SEMICONDUCTORS
U1 -LP324
micropower quad op -amp
(National), integrated circuit
U2-CD4040 12-stage ripple carry
binary counter, integrated circuit
U3 -LM556 dual oscillator /timer,
integrated circuit
U4 CD40106 hex inverting Schmitt trigger, integrated circuit
U5-LM2931A 5 -volt series, lowdropout, voltage regulator,
integrated circuit
MPSA12 Darlington NPN
silicon transistor
Dl, D2-1N914 general -purpose,
small- signal silicon diode
Ql-
Fig. 3. The final version of the circuit was assembled on a printed-circuit board,
measuring about 3 x 2 inches. A template of that layout is shown here full size.
RESISTORS
(All fixed resistors are 1/4-watt, 5%
units.)
R1, R2, R11, R16- 100,000-ohm
R3 -1000 -ohm
MICI
R4
R5'
R9-39,000 -ohm
R5-75,000 -ohm
R12I
R4,
R6-2200 -ohm
R7, R8- I1,000-ohm
R10-56.000 -ohm
R12- 10,000 -ohm
R13 R15- 1- megohm
CAPACITORS
C3-0.1-}1F, monolithic
C4, C5-0.01 -µF monolithic
16 -WVDC, tantalum
C7, C8 -1 -1.1.F, 16-WVDC, tantalum
C9-22- aF, 16-WVDC, miniature
electrolytic
ADDITIONAL PARTS AND
MATERIALS
SI -SPST slide switch
microphone
BZ1-6 -volt electronic buzzer (RS
#273 -054)
-9
-volt transistor-radio battery
Printed-circuit materials, enclosure,
1/4 x 24 -inch web strap, adhesive
backed cushion feet, battery holder
and connector, wire, solder,
hardware, etc.
BI
Note: The following items are
available from Futronics, 22524
Millenbach, St. Clair Shores, MI
48081. A complete kit of parts,
$29.95; printed- circuit board only,
$9.95. Please add $3.00 for
shipping and handling. Michigan
residents please add appropriate
sales tax.
38
IC31R6
U2
R2
D1* *D2
-R3U1
R11
U3
C5I R7I
IR8
+
U4
-J-
R10
Ç9
C1-2.2 -µF, 16 -WVDC, tantalum
C2- 0.047 -p.F, monolithic
MICI- Electret
R9IC4I
-
--C1-+
R1I
Ç2
R13
C8
D
.
--
--i
R15
'S1Z
B1
F-O
Ç6
o
T
Fig. 4. Once you've obtained the board and the parts that will populate it (either on
your own or by ordering them from the supplier listed in the Parts List), use this parts placement diagram to locate and install the components in their proper positions.
other approximately 5/,o x 1/4 inches
for the slide switch.
Connect short lengths of hook -up
wire to the buzzer and the switch, connect the wires from the off -board
components to the appropriate
points on the printed- circuit board.
Mount the printed- circuit board,
switch, and buzzer to the enclosure,
and then secure the nylon web strap
to the side of the enclosure using a
pair of 4/40 screws and nuts. The strapping used to secure the project to the
dog's neck is available at most sports
and army surplus stores.
Cut off any excess strap length after
sizing it to the dog's neck; the free end
of the strap should be melted to avoid
fraying. Finally, install the IC's in their
respective sockets, install a 9 -volt battery, and close up the project box.
www.americanradiohistory.com
Operation. Using the circuit
is
easy.
Simply strap the Dog Bark Inhibitor to
your dog's neck (be sure to orient the
unit so that the microphone is up), turn
the unit on using S1. Any long duration
or repeated barking by the dog will
cause the buzzer to sound for one half
second. If greater sensitivity is desired,
increase the value of R5.
A longer free -barking period can
be achieved by increasing the
number of counts U4 allows before
turning on the buzzer (that can be
done by cutting the trace to pin 13 of
U2 and moving the wire to the Q9
output pin 12 or the Q10 output pin 14).
The project has been used on the author's dog for more than a year and
has stopped the dog's nuisance barking and has restored neighborhood
harmony.
On -Board
"IPIIr
Navigation Systems
for your Car
On -board navigation systems, satelite positioning, roadside beacons, and many more
developments may dramatically change the relationship between man and his car.
BY BILL SIURU
Irs your first trip to this city and you
have much business to conduct.
You don't have any time to spare,
especially drivinc around lost. Therefore, you spring for a deluxe rental car
complete with an on -board navigation system and cellular phone.
Slipping behind the wheel, you
immediately notice the small CRT
screen in the center of the dashboard. After reading the brief user friendly instruction pamphlet, you flip
on the ignition switch and the screen
lights up with a monochromatic map
of the city's streets. An icon on the
screen displays your current location.
Pressing one of the buttons along the
side of the CRT, the map changes to a
menu. Scrolling through the menu,
you enter your first destination. Switching back to the map display, you see
another icon at the destination plus
the streets you have to travel highlighted. Also shown is the current corn-
pass direction and the mileage to
your destination. This trip is going to be
a piece of cake!
Moving out of the parking garage,
you glance to your right and see the
map moving with the vehicle as you
turn right or left, or even back up. To
help keep your orientation, the top of
isting of motels and hotels in a familiar Yei#ow Pages format. You choose
one and then use the cellular phone
to make the reservation. As you go
through this menu, you note for later
reference that there are also listings of
restaurants, entertainment attractions, -owing services, and even local
the screen represents "straight
happenings with dates, locations,
ahead." Halfway to your destination,
the system starts "beeping" quietly to
get your attention. Without taking your
eyes off the road, you notice a "congestion" warning and a new route is
suggested to avoid the problem. As
you near your destination, you press
another side button to zoom -in on the
display so the local streets are shown
in greater detail.
After parking, but before leaving
the car for your appointment, you remember you need to make a hotel
reservation. Pressing another button
brings up a menu that gives you a
and times.
www.americanradiohistory.com
SOL nds like a bit of science fantasy?
Well, in -car navigation systems with at
least most of these capabilities are
starting to appear on the market in
Europe, Japan, and even the U.S. For
instance, some 50,000 navigation systems are already in operation in Japan. In Europe and the U.S.,
navigation equipment is starting to
appear in police cars, fire trucks, ambulances, express delivery vans, and
other time-critical vehicles. "Civilian"
affermarket units are now on sale in
the U.S. as well.
39
How They Work. Let's look at the
Blaupunkt Travelpilot by the Robert
Bosch Corporation, which is already
offered in the United States as well as
in Europe with a suggested retail price
of $2,495. The Travelpilot uses "dead reckoning" navigation, a technique
first used by mariners and aviators,
combined with map matching.
Dead reckoning uses speed, time,
and compass direction to continuously compute the vehicle's estimated location with respect to a known
position. Dead reckoning is sometimes referred to as "deduced reckoning." That is because you are
deducing where you must now be
given that you have, for example, traveled for 15 miles (determined by an
odometer or a speedometer and a
clock) due east from a known starting
The two wheel sensors determine
when the car is turning and moving at
different speeds. The heart of the Travelpilot system is the "black box" located in the car's trunk or under the
seat in commercial vehicles. Inside is
a 600- megabyte CD -ROM player and
a navigational Computer. The compact disc stores the EtakMap digitized
maps of the required geographic region used for map matching. The Travelpilot computer consists of a 16 -bit
processor with 8k SRAM, 64k EPROM,
and 512k DRAM.
The Travelpilot's real -time moving
map display (see Fig. 2) shows current
location and the alternate routes to
1).
get from point A to point B. The distance and compass direction to the
selected destination is also shown.
The map display scrolls and rotates
under the fixed cursor placed over the
ever -changing current location. Map
movement corresponds to the car's
movement on the map and the road.
Destinations can be selected by city
locale, street address, or the intersection of iwo streets. Up to 99 user-programmed destinations can be stored
in the memory. According to
Blaupunkt, a vector -type video display was chosen for the system because it is easier to read than a.TVstyle raster -scan display. The driver
position.
In simple dead reckoning, you
would plot your course on a map with
a pencil. That roughly corresponds to
map matching in a navigation system
like the Travelpilot. Here the path
being driven (determined from dead
reckoning) is compared, or technically called "cross- correlated," with
the available paths that are on the
map. That is like tracing your path on a
piece of paper, putting it over a map
and moving it around until it matches
up with the roads on the map. Of
course, in a computerized navigation
system, this correlation is done using
hundreds of algorithms (computerized equations) and a digitized map database. Therefore, if you have
driven a path on existing roads, it will
correspond to a particular path in the
map database. Even if you drive off
roads and into parking lots, the algorithms look at the "bigger picture"
to find out where you probably are,
Speaking of maps, Etak Inc. in Menlo Park, California is the major producer of digitized maps for use in onboard navigation systems as well as
many other applications from taxi
and ambulance dispatchers to
public utilities and travel agents.
40
Some 75- percent of the U.S. is covered by at least one version of an
EtakMap digitized map, as are extensive areas of Germany, France, and
the Netherlands.
Travelpilot uses an electronic flux gate compass and dual wheel sensors to measure direction and distance traveled, respectively (See Fig.
Fig. 1. The computer and CD ROM of the Blaupunkt Travelpilot are located in the
trunk. The electronic flux-gate compass is located over the rear window, and speed
sensors are located in the rear wheels.
BLAUPUNIR TRAVELPILOT
VEHICLE NAVIGATION SYSTEM
DISTANCE TO
DESTINATION
DIRECTION TO
DESTINATION
*MAIN MENU
'MAP TOP NORTH
DESTINATION INFO
OTHER ST. NAMES
SHIFT CURSOR
LEFT OR RIGHT
COMPASS
NORTH
DESTINATION LOCATED
BETWEEN TWO STARS
ZOOM OUT
MAP SCALE
Ye -30 MI.
1 MILE
SHOWN
ZOOM IN
CURRENT LOCATION
AND DIRECTION
OF TRAVEL
CURRENT
DESTINATION
BRIGHTNESS
CONTROL
*NO ACCESS WHEN VEHICLE IS MOVING.
Fig. 2. This is the display CRT for the Blaupunkt. Control buttons are located along
either side, as shown.
www.americanradiohistory.com
can zoom the display in or out for
more or less detail as is needed.
IR -DATA TRANSCEIVER
Obtaining More Accuracy. In the
simplest case, you could dead reckon
with nothing more than a compass
and odometer, plus a map and pencil. However, these "sensors" are pretty
crude and location errors can quickly
accumulate. Even precision wheel speed sensors and flux -gate compasses are not prefect. Therefore,
while on -board navigation systems
like Travelpilot can be completely self contained and give good results,
many on -board navigation systems
use external and /or internal methods
to further improve their accuracy. External sources involve interfacing with
the Global- Positioning System (GPS)
satellites in space (for more on this,
see the July, 1992 issue of Popular
Electronics), Loran transmitters, or
roadside and overhead beacons. The
downside is that these interfaces usually require user fees or, for example in
the case of beacons, major investments in infrastructure. Internal methods, on the other hand, require
additional inertial -guidance components. However, map matching is still a
necessary ingredient to precisely locate the vehicle on the map in just
about every system.
The prototype Motorola In-Vehicle
Navigation System uses position data
from GPS satellites to enhance the accuracy of the vehicle's current location. Besides GPS data, the navigation
computer receives measurements
from a differential odometer and
magnetometer to provide dead reckoning. A digital map stored in the CD
ROM is used for map matching, route
planning, and route guidance. Drivers
are provided instructions via both a
simplified dashboard video display
and synthesized voice commands.
Germany's Siemens Automotive Ali Scout navigation system (see Fig. 3)
communicates with infrared beacons
mounted on existing traffic lights. An
infrared transmitter /receiver mounted
on the back of the rear-view mirror
receives information from the
beacons. Infrared communication
diodes emit
incoherent beams eliminating interference problems caused by multipath propagation or when several
transmitters are operating in mutually
overlapping regions. Being an in-
was chosen because
IR
MAGNETIC
FIELD SENSOR
VEHICLE WIRING
IR- KEYBOARD
LEFT FRONT SPEAKER
OF VEHICLE RADIO
Fig. 3. These are the in- vehicle components for the Ali -Scout navigation system. Note
the IR remote keyboard usedfor entering data and controlling the system.
ANGLE OF DEFLECTION
POLARIZER
PHOTODIODE
PHASE MODULATOR
OPTICAL -FIBER COUPLERS
PHOTODETECTOR
Fig. 4. This is a depiction of the optical -fiber gyroscope used in Nissan's new onboard navigation system available in Japan. Any angular deflection of the large disk
results in a variation of angular velocity in the fiber.
coherent radiation source, simultaneous infrared flashes can never
extinguish each other, only amplify
each other. Even the most complicated intersections pose no problems
with IR. The IR signal is transmitted at a
125k baud rate at a maximum range
of 60 meters (200 feet) so that the
vehicle
is
only within the transmission
range when passing near the
beacon.
The Ali -Scout's dead reckoning navigation computer uses measurements
from a magnetic -field sensor that
measures the earth's magnetic field.
Distance travelled
is
determined
using a speed sensor attached to the
odometer or transmission.
One potential problem with onboard navigation systems is that complex map displays can overtax driver
attention especially when trying to
cope with demanding urban -traffic
conditions. Therefore rather than
www.americanradiohistory.com
using somewhat more distracting
map displays, the Ali -Scout uses a
dashboard display with simplified
graphic symbols for instructions. For
example, arrows show turn directions
and a bar graph decreases in size as
the corner approaches. The visual display is augmented by audible instructions as well. A 36 -key handheld
alphanumeric keyboard is used for inputting destinations either in the form
of street names or map coordinates.
The memory has the capacity for 100
destinations. Some other navigation
systems allow both maps and symbolic instructions by changing displays on the screen.
Several navigation systems are already coming into routine use in Japan. For example, Nissan has just
introduced its third -generation vehicle- navigation system that is optional
on its Cedric, Gloria, and Cima models sold in their home market. The sys-
41
tern uses a new optical -fiber gyroscope (shown in Fig. 4) to accurately
sense the direction of vehicle motion.
The gyroscope uses 100 meters of 0.3mm optical fiber coiled into a 130 mm diameter loop. The gyroscope
measures angular velocities by determining the difference in the time of
light traveling clockwise versus counterclockwise in the circular optical -fiber path. The time differences, which
are actually frequency shifts, can be
correlated with the rate of angular
motion. Bumpy roads are no problem
because this type of gyro is not affected by shock in the horizontal
plane.
Nissan also uses roadside electronic beacons that broadcast their
specific location coordinates via digital broadcasts at 2.5 GHz. They are
deliberately weak to limit the reception area to approximately 35 meters
before and after the beacon in a strip
that is only about 15 meters wide. This
avoids any possibility of cross- beacon
interference. Beacons are already
being set up along major roadways in
Tokyo, Osaka, and Nagoya, with even
more beacons to be installed in the
future. Data broadcast by the
beacons include intersection names
and coordinates, distances from a
central point, destinations of roads
leading from the intersections, road
restrictions, and more. The optical -fi-
ber gyroscope and roadside
beacons are used with dead reckoning and a digital -map database to
provide greater accuracy than previous Nissan systems, which relied only
on position updates from GPS satellites.
Nissan uses a dual- system map matching logic. In the micromatching
mode, the calculated vehicle location is matched every second to
roads in the internal map database.
Here the searching is done in a small
zone by detecting the angular velocity of the vehicle. In the mac romatching mode, matching is done
about every 50- meters of travel to
compare vehicle direction with roadway shapes. Searching in the mac romatching mode is done in a wider
zone using 5- kilometer segments. The
map database is stored on a single
CD ROM. According to Nissan, vehicles can be located within five
meters.
More Than Finding Your Way.
Probably the greatest contribution
navigation systems can make to society is helping to reduce urban -traf-
TRAVEL TECHNOLOGY
VARIOUS AGENCIES,
DEPTS., ETC.
FLORIDA DEPT. OF
TRANSPORTATION
INCIDENT
INFORMATION
TRAFFIC
INFORMATION
NETWORK
FREEWAY
MANAGEMENT
CENTER
FEDERAL HIGHWAY
ADMINISTRATION/
ORLANDO
TRAFFIC
INFORMATION
TRAFFIC
MANAGEMENT
TRAFFIC DATA
CENTER
TRAVEL/EVENT
INFORMATION
i
LOCATION
TRAVTEK
INFORMATION
AND SERVICE
CENTER
TIMES
TRAFFIC
SIGNAL
SYSTEM
AMERICAN AUTOMOBILE
ASSOCIATION
CELLULAR
TELEPHONE
42
TRAVEL
TRAVTEK
VEHICLES
GENERAL
MOTORS
NCITY OF ORLANDO
GUIDANCE
INFORMATION
Fig. 5. This block diagram shows the interfaces between on -board equipment,
information sources, and the Traffic Management Center that is being used in
Orlando's TravTek system.
www.americanradiohistory.com
fic congestion and its byproducts:
wasted fuel, additional pollution,
wasted time, and frayed nerves. There
are several major Intelligent Vehicle/
Highway System (IVHS) demonstration
projects underway in several countries that mate on -board navigation
equipment with centralized traffic management systems.
The $12 million Travtek (which
stands for Travel Technology) experimental program in Orlando, Florida
probably represents the most ambitious NHS demonstration project underway in the U.S. today. For this one year demonstration program, 100
Oldsmobiles have been fitted with an
in -dash CRT monitor, TravTek navigation hardware and software, plus radio gear for two -way communication
with the Orlando Traffic Management
Center. Seventy -five of these specially
equipped cars are part of Avis rental car fleet in Orlando. The rest will be
evaluated by high -mileage drivers.
TravTek is a joint program with the
American Automobile Association,
General Motors, the Federal Highway
Administration, Florida Department of
Transportation, and the City of Orlando.
For navigation, TravTek uses corn puterized dead reckoning and map
matching with updates from the GPS
satellites to pinpoint vehicle location
within a 1200 square-mile area that
includes 10,000 roadway miles. After
the driver enters the desired destination, TravTek computes the best route
and then guides the driver to the destination using both visual and synthesized voice commands.
TravTek is much more than an onboard navigation system. It also advises drivers of traffic congestion and
delays (see Fig. 5). Besides warnings,
the system automatically provides reroutings to avoid the problems using
advisories transmitted from the Traffic
Management Center. The in- vehicle
TravTek processor receives the advisories, then determines if the driver's selected route is affected, calculates a
new route and informs the driver that
an alternate route is available. These
advisories are generated using data
from several sources including the
city's centralized traffic signal system,
the Florida Department of Transportation's freeway- management system,
the MA TravTek Information and Ser(Continued on page 92)
A Telephone -Line
cy oscillator; the other two
gates (U1 -a and U1 -b) are
used to buffer the output of
the oscillator, which is used
to drive LEDI.
Resistors R1 R3 sample the
phone line voltage and divide it to one third of its original value. When the voltage
across R2 exceeds 5 volts, (indicating a phone line voltage of at least 15 volts), the
oscillator is gated off and
LEDI remains dark.
When the telephone rings,
the line voltage goes to 100
volts AC, which puts 33 volts
across R2. That is beyond the
How many times have
you lifted the telephone receiver from
the hook, in a vain attempt
to make an important call,
only to find that the phone is
in use. Or, what about those
times when you're involved
in a confidential call and
somebody lifts the receiver
off hook Just in time to hear
just enough of the dialogue
to misconstrue the meaning
of your conversation. Or
maybe while you're trying to
upload or download a time dependent, critical computer document, someone
takes a remote receiver off
hook, allowing noise (which
can lead to glitches) to get
into the transmission. Such
events can lead to interfamily conflicts.
Wouldn't it be nice if your
home telephone contained
circuitry that would let you
know when the line is being
used (a feature that is readily
available in most office environments). Well, with the
Line -In -Use Indicator described in this article, you
can add such a feature to
your present home -telephone network. The circuit
which uses a bright, blinking
LED to indicate whether the
line is in use -can be installed next to any telephone to warn other family members
not to interrupt your modem connections or private conversations.
-
maximum rating of the
CMOS IC, not to mention
that the polarity is backward
half the time. So why doesn't
the IC fry? The answer has to
do with the input protection
diodes built into every B -series CMOS logic chip (see
Fig. 2). Because R1, R2, and
are so large, the input current is tiny even when the
voltage Is very high. The diodes inside the chip shunt
the excess voltage to the
R3
In -Use
Indicator
How It Works. The indicator works
by sensing the voltage across the telephone line. The line voltage is normally 48 volts DC when the phone is
on hook, and drops to about 2 to 10
volts when a telephone Is off hook.
When the voltage across the telephone line drops below 15 volts, an
LED begins to blink. While many circuits of this ilk pirate power from the
phone line for their operation, this one
doesn't... it is powered from a 9 -volt
transistor radio battery. The reason is
that there isn't always enough power
Keep others from barging
in on your telephone
Conversations
BY MICHAEL A. COVINGTON
available to light an LED brightly. The
power supply arrangement used for
the project ensures that the LED is always bright and prominent.
Figure 1 shows a schematic diagram of the Line -In -Use Indicator. At
the heart of the circuit is a CD4001B
quad CMOS NOR gate. Two of the
gates from that chip -UI -c and U1d-are configured as a low -frequen-
www.americanradiohistory.com
battery, which absorbs it.
Since the current is only a
couple of microamps, it has
no effect on the battery.
Construction. The author's
prototype was assembled
on a small section of per fboard. As always, it is recommended
that an IC socket be provided for U1.
Begin construction by first mounting a
14 -pin IC socket to the perfboard. Flip
the board over and then mark the pin
1 terminal of the socket, which will
serve as a reference point. Now,
guided by Fig. 1, wire the circuit together using point -to -point wiring
techniques.
When it comes to the LED, there are
a couple of ways to handle it. The LED
can be wired to the board using
hook -up wire, or It can be installed
with its leads left long enough so that
LED lens protrudes through the enclosure's front panel.
After the circuit has been as-
43
R4
4.7
4.7
12
GREEN
o-- 'NVr
R1
---
22MEG
13
U1-d
1/4
1/4
MEG
11
1M
CD4001B
10
I(
Cl
'/4 CD4001B
TO
SEMICONDUCTORS
.04
U1- CD4001B
(or MCI4001B) quad
CMOS NOR gate, integrated circuit
LED1- Light- emitting diode, any
color
CD4001B
3
TELEPHONE
LINE
(SEE TEXT)
5
RESISTORS
2
R2
6
U1-b
14
22MEG
1/4
=MN
CD4001B
R6
27052
LEDI
9V
R3
22MEG
1M
RED
Fig.
(All resistors are V8 -watt, 5% units.)
Rl, R2, R3-22- megohm
R4, R5-4.7-megohm
R6-270 -ohm
B1
o
PARTS LIST FOR THE
TELEPHONE LINE -IN -USE
INDICATOR
R5
MEG
the heart of the Line -In -Use Indicator is a CD4001B quad CMOS NOR gate.
Two of the gates (UI -c and Ul -d) are configured as a low frequency oscillator; the
other two gates (Ul -a and UI -b) are used to buffer the output of the oscillator, which is
used to drive LEDI.
1. At
ADDITIONAL PARTS AND
MATERIALS
C1- 0.04-1F or 0.05 -p.F, ceramic -
disc capacitor
Bl
-volt alkaline, transistor -radio
battery
Pertboard materials, enclosure, 14pin IC socket, battery connector,
wire, solder, hardware, etc.
-9
telephone line through the appropriate hole in the enclosure and connect it to the circuit. The type of wire
and the termination used for that will
be determined by the terminal block
used in your phone installation. The
author used Iwo lengths of wire that
he twisted together (as in "twisted
pair "). However, if your home -telephone network has modular jacks,
modular cable is the way to go; in that
case, simply connect the red and
green wire of a modular telephone
cable as shown in Fig. 1. Once the
cable is connected, the LED can be
press- mounted in the front panel LED
hole.
The author's prototype was assembled on a small section of perfboard and housed in a
plastic enclosure that comes complete with a built-in battery compartment.
uDD
FRAGILE
MOSFET
NEEDING
PROTECTION
sembled, check your work for construction errors, particularly around
the IC socket. If all is well, install the IC
in its socket.
prototype was housed
a plastic enclosure with battery
compartment (available from Radio
Shack as part 270 -293). The only enclosure preparation required is to drill
Iwo holes in the enclosure; one in the
front panel of the enclosure through
which LEDI will protrude, and the
other in the side of the enclosure for a
telephone line cord for connection to
the board.
Once the holes are drilled, feed the
wire that will connect the circuit to the
The author's
in
INPUT
Vs$
44
Fig. 2. When the telephone rings, the
line voltage rises to 100 volts AC,
placing 33 volts across R2. That voltage,
which is applied to the input of UI -d,
would normally fry the chip, but because
the CD400IB has input protection diodes
(as shown here) built into it, that doesn't
happen in our circuit.
www.americanradiohistory.com
Installation. Installation is a simple
procedure; just connect the cable
from the project across the telephone
line, as indicated in Fig.
1.
Resistor
R1
should go to the positive (green) wire
and R3 to the negative (red) wire. In
normal operation, the LED will be off if
the line is idle; the LED will blink if a
telephone is off hook, a ringing signal
is present, or the line is dead (0 volts). If
the LED never stops blinking, try swap-
ping the connections.
Don't install the battery until you're
ready to connect the indicator to the
phone line; if you do, the LED will blink
constantly and run the battery down.
Conversely, don't leave the indicator
attached to the line without a battery
installed; it relies on the battery for
overvoltage protection.
throughout the wiring
system. The circuit's
250 -Hz squarewave
output, which is rich in
harmonic signals that
In these difficult
economic times,
many home owners are opting, wher-
ever possible, to do
their own home repairs and remodeling.
Do- it- yourself home
repairs often entail
spending many hours
trying to trace the AC
wiring through walls
reach into the AM
broadcast band, allows the signal to be
traced through the
house or other wiring
with an inexpensive
AM transistor radio. The
radiated signal, when
detected by an AM receiver, produces a
buzzsaw -like sound in
the receiver's speaker.
and junction boxes.
Remodeling, such as
adding a new window
or door to your home,
often requires that you
cut a section out of a
wall. When hacking
through a wall, you
had better know the
location of the elec-
In
through C4 and is delivered to output jack
J1 (the open -loop output); the signal also
continues on through
47 -ohm current- limit-
trical wiring or it's lights
out.
A simple solution to
those and other similar
ing resistor R6 (which
a signal through your
closed -loop output).
Those output jacks,
along with J3 (com-
automobile's eleccan be
found in the McTrak
trical system
job that might otherwise require hours of
is
used to protect the
tracker's output from
overload) to J2 (the
wire -tracing dilemmas-such as tracing
wire -tracing circuit described in this article.
The McTrak can turn a
the other path,
the signal goes
Cut those seemingly insurmountable
jobs down to size
cutting, whacking,
and pulling into child's play (well almost), cutting your work time from a
few hours to only a few minutes.
The McTrak is easy and inexpensive
to build, and best of all, there is
nothing difficult about using the unit.
All you have to do is connect the
McTrak to the wire of interest and,
using a portable AM receiver, trace a
signal (put out by the McTrak) to its
final destination.
How It Works. A schematic diagram
of the McTrak is shown in Fig. 1. At the
heart of the circuit is a 567 tone decoder. The tone decoder (U1) is configured as a simple astable, square wave oscillator, operating at about
250 Hz. The 250 -Hz output of the
squarewave oscillator, at pin 5, is fed
to the base of Q1 (a 2N3904 general purpose NPN transistor), which in this
application, functions as a buffer
stage. The alternating output of U1
BY CHARLES D. RAKES
mon), are used when
conditions are less
ng than optimum. (We'll
wire
give examples of how
and when to use those
jacks at the appropriate time later in this article.)
causes Q1 to switch on and off in time
with the drive signal.
The output of Q1, taken from its collector, is fed through capacitor C2 to
Q2 and Q3-a second 2N3904 NPN
unit and its companion 2N3906 PNP
transistor, respectively-which form a
complementary pair. Together, those
transistors alternately amplify both
halves of the applied signal; e.g.,
when one transistor is off the other
one is on. That pair of transistors provides a low output- impedance signal
source that can be used to drive either an open- or closed -loop circuit.
The output of the complementary
pair (Q2 and Q3) splits along two
paths; in one path, the output of the
complementary pair is applied to C5,
causing the 250 -Hz output of the
complementary pair to be induced
into the AC wiring and radiated
www.americanradiohistory.com
-traci
Construction. Building the McTrak
is
simple and the parts layout is not critical, so just about any construction
scheme will suffice. However, the author's prototype of the circuit was assembled on a printed- circuit board. A
template for that printed- circuit
layout is shown in Fig. 2. If you optto go
the printed- circuit route, follow the
parts- placement diagram shown in
Fig. 3.
As usual, start by installing
the passive components (resistors, capacitors, etc.) followed by the semicon-
ductors, double- checking all part
locations and their orientations as
they are installed on the board. Once
the electronic components have
been iinstalled, connect a 9 -volt battery connector to the board at the
points indicated in Fig. 3. Be sure that
the proper polarity is observed.
45
.-Cl
.068
10K,
)1
47
0-*1I----
+
+9V
C5
.01
2N3904
5
81
S1
PK
R3 4
1K ¡
R1
47K
6
C3
R4
)1
R2
4.7K
U1
C2
667
4.7
+
C4
47
Q3
2N3906
01
R6
47x2
2N3904
C6
"^
t~O
.01
CPLI
117V
J1
OPEN LOOP
o J2
R5
10K
CLOSED LOOP
#
J3
° COM.
Fig. 1. At the heart of the McTrak is a 567 tone decoder, configured as a simple squarewave
oscillator, operating at about 250 Hz.
side and prepare the enclosure.
The author's prototype was housed
in a 4% x 2°/16 x 1 °/16 -inch plastic
project box (available from Radio
Shack and other sources) that is slotted to hold small circuit boards in
place. The circuit board was sized to fit
the case's internal slots.
It will be necessary to drill holes in
the enclosure for the off -board components: S1 (along with its mounting
hardware), J1 -J3, and PLI. Note that
although the author used a slide
switch for S1, there is no reason that a
toggle or even a locking pushbutton
(push on /push off) switch could not be
substituted. Mount switch Si to one
side of the cabinet, and the three output jacks on the opposite side. Then
PARTS LIST FOR THE
MCTRAK
SEMICONDUCTORS
lil -LM567
tone -decoder, integrated
circuit
Q2- 2N3904 general -purpose
NPN silicon transistor
Q3- 2N3906 general- purpose PNP
silicon transistor
Ql,
(All fixed resistors are 1/4-watt, 5%
units.)
R1-47,000-ohm
R2 --4700 -ohm
H
R3 -1000 -ohm
11/4 INCHES
R5- 10,000 -ohm
CAPACITORS
C1- O.068 -p,F, 100 -volt Mylar
Fig. 2. The author's prototype of the circuit was assembled on a printed- circuit
board, the template for that printed -circuit layout is shown here full size.
C2- 4.7 -i.F, I6-WVDC, electrolytic
C3, C4- 47 -µF, 16 -WVDC,
-C1-
R1-
-R5-
_--0
J3
COM.
PL1
-C6
B1
1----II---S1
R3
O
O
O-
C3
---d
C4
U1
+ C2
J1
OPEN
LOOP
C5
-R4-
02
-R6- --O
J2
CLOSED
LOOP
Fig. 3. Follow this parts -placement diagram when assembling McTrak's printed-circuit
board. As usual, start with the passive components, followed by the semiconductors,
double- checking the part's location and orientation as it is installed.
46
After all of the on -board components have been installed, check your
work for potential problems-solder
bridges, cold solder joints, and so on.
-9
B1
-volt transistor -radio battery
SI -SPST slide switch
J1
-See text
Printed- circuit materials, enclosure
(Radio Shack #270 -222), molded
AC power plug with line cord, 9volt battery holder and connector,
wire, solder, hardware, etc.
Note: The circuit board and all of the
R6-47-ohm
--01
ADDITIONAL PARTS AND
MATERIALS
J3
RESISTORS
R4,
electrolytic
C5, Có 0.01 -µF, 500-1000 -WVDC,
ceramic -disc
parts that mount on it are available
for $14.95, plus $1.00 shipping
and handling from: Krystal Kits,
P.O. Box 445, Bentonville, AR
72712. Arkansas residents please
add appropriate sales tax.
using hook -up wire, connect the
switch and the three jacks to the circuit board at the appropriate points.
Once that is done, mount an AC
plug with line cord to one end of the
enclosure. That can be accomplished
by first passing the plug's line cord the
through a 1/8 -inch hole in one end of
the enclosure, and then clipping off
the excess cord length and connecting the line cord to the circuit
board as shown in Fig. 3. After that is
done, the plug can be secured to the
enclosure using hot -melt glue.
When you are satisfied that the circuit
board contains no errors (of the
nature usually associated with hobbyist projects), place the board to the
www.americanradiohistory.com
Check Out and Use. To check the
operation of the McTrak, first install a
(Continued on page 98)
By monitoring the VHF low-band for skip, you could easily make some
wonderful long- distance contacts.
BY LAURA QUARANTIELLO
The transmissions were weak,
scratchy and, more often than
i
not, lost behind the other
voices on the frequency. I'd been listening to 33.7 MHz for two days now
and still had failed to hear any information that would help me to identify
the station speaking. It had become a
minor obsession over the past couple
of hours to positively identify the distant fire -department dispatches.
Unfortunately, given the changing
nature of the atmosphere, it was likely
that when woke up the next morning
and turned on the radio, 33.7 MHz
would be silent and the transmissions
gone. To understand how a long-distance transmission can appear and
disappear like that, we'll have to do a
quick study of radio -wave propagation -the near magic of what happens to a radio wave once it heads
off into the atmosphere.
I
One Little Wave. When a radio signal or wave leaves the antenna of a
transmitter, it becomes, in theory, two
distinct parts: a ground wave that
travels along the surface of the Earth
and a sky wave that travels out into
the sky. The ground wave travels a
short distance before it becomes absorbed by the Earth, but the sky wave
is much more resilient and that's the
wave low-band, distant -transmission
listeners tune -in to.
The sky wave travels on its merry
way, high up into the wild blue yonder,
until it encounters the ionosphere.
That layer of the Earth's atmosphere,
some 150 to 200 miles high, is constantly bombarded by the Sun, which
charges the ionized gases of the
ionosphere. When a sky wave hits that
layer of charged gas, it is partially reflected. Some of the part of the wave
that is not reflected is absorbed by the
gas, and the remainder flies into
deep space. The portion that is reflected returns to Earth at an angle,
which means that it comes down
many thousands of miles from its point
of origin. That phenomenon is known
as "skip."
Skip is almost a mystical thing, af-
ceive VHF skip transmissions. In fact,
any scanner that will search the range
of 30-50 MHz will do nicely. Having a
search feature is important, because
you'll definitely want to program -in
short ranges of frequencies and let
the scanner do the work.
An outdoor antenna is not man-
datory, but it will improve your
chances of hearing transmissions tenfold. A good all -band ground -plane
antenna does nicely, but a beam antenna can have advantages if you
are searching for transmissions from a
specific direction. Since the prevailing
atmospheric conditions have the
most to do with reception, whatever
you use should pull in some signals, so
give it a try.
Frequency guides are a great resource if you're serious about identifying the stations heard. For example, a
complete set of Police Call magazine's frequency directories is invalu-
fected by sunspots, weather, and
able for tracking down domestic
even the time of year. It can also be a
scanner enthusiast's best friend if you
know how to take advantage of it.
public-safety stations. For military stations, try a federal frequency directory
such as Tom Kneitel's Top Secret Registry of US Government Frequencies. A
good map book of the United States is
also handy.
Equipment. You don't need a control room full of radios in order to re-
www.americanradiohistory.com
I,:;
cations activity all across the low
band from American and foreign
troops in Saudi Arabia. Voices from
Central American stations, Panama,
Honduras, and the Dominican Republic are regularly heard engaged
in US military operations. Furthermore,
lots of counter -drug missions take
place on the low band, as well as a
large amount of fire communications.
Fish and Wildlife officers, whose activities often take them far from normal radio range, can often be heard
talking on frequencies between 31
and 32 MHz.
uw.optir
4
2209
2592 rn
t59t
FORT BRAGG, NC
m
"""qlk
DX
TATE OF
CATCHES
Fig.
38.900
LOUISIANA FWS
31.060
Identifying Stations. The first order
of business when you come across an
active frequency is to take down
some of the information you hear
coming across the speaker. Call signs,
place names, and unit ID's are all
helpful. More than once I've tracked
down a frequency user by tracing city
names through a map book.
Here's an example: say, 42.12 MHz is
active with a dispatcher calling herself "San Diego." Looking up San Diego in a map book will reveal a
California location. Drag out volume
nine of Police Call, check all the licenses under 42.12 MHz and you'll
find a listing for the California Highway
Patrol San Diego Office.
Military stations can be difficult if
call signs such as Alpha Six Echo" are
used, but if you listen long enough you
might hear the base name or a unit
number. When that happens, check a
federal frequency book for active stations on the frequency to get you
closer to a positive ID.
can tell from these catches logged by the author, skip can really help you
pull -in transmissions from all over the country.
1. As you
Finding Skip. Frequencies on the
low band-30 to 50 MHz-are most
affected by skip because of their long
wavelengths. Frequencies on the
to scan between these two values.
This is about as low as typical scanners
will receive and is a good place to
higher VHF bands tend to skip less.
don't consider 50 MHz the absolute
top of the possible skip range. Occasional forays above 50 MHz have netted some interesting catches, but for
the best results, "go low"
Searching through the basement of
the VHF band, your chances improve
communications, forestry reports,
start. Here you'll come across business
I
drastically. On a good day, it isn't unusual to hear communications from
thousands of miles away, sometimes
even from Central America, Canada,
or overseas. The key to hearing all this
knowing when and where to listen.
Since skip is affected primarily by
the actions of the sun, it almost goes
without saying that daytime is the best
time to listen. Try between 9 A.M. and 7
P.M., or whenever local dusk occurs. If
you're shortwave equipped, listen at
18 minutes past each hour for propagation reports from WWV on 2.5, 5, 10,
15, or 20 MHz. The solar flux number
is
they give reflects the amount of
ionization of the ionosphere's F2 layer,
and so the possibility of picking up
long -distance transmissions.
target specific frequencies, which
I
I
check for communications. For instance, 38.9 MHz is a popular military
range -control frequency that have
programmed into my regular scan
bank. If hear communications on this
channel, know that skip is present
and set-up search ranges to see what
other frequencies might be active.
Try programming in the range from
30.0 to 31.0 MHz and set your scanner
I
I
I
power and water utilities, and some
public safety and military communications. If you find active distant stafions here, work progressively higher.
On some days only a small swath of
frequencies will be affected, and on
others you won't know where to tune
first because of all the activity.
The region between 31 and 33 MHz
is a super place to look for military
communications, as are the 38 -39
MHz and 40-42 MHz areas. Fire departments can be found primarily between 33 -35 and 37 -38 MHz.
Highway patrol, a good target for beginners, can be found operating between 42 -43 MHz. These ranges will
get you started. Take a look at the
back of an issue of Police Call for their
Consolidated Frequency List, which
will further guide you.
Don't be afraid to experiment and
seek ranges beyond the norm for skip.
frequently scan from 49.0 to 49.7
MHz, just below the cordless telephone /baby monitor band, which
yields up such catches as military range communications (like Camp
Pendleton, California at 49.0 MHz),
and tactical operations (such as Army
Explosives Ordnance Disposal on 49.7
and 49.8 MHz). You never know what
you'll find: occasionally even hear
live horse -race announcements on
I
I
41.725 MHz.
During the Gulf War, scanner
monitors reported heavy communi-
www.americanradiohistory.com
DX'ing Low Band. Searching for distant signals (DX'ing) can be an engrossing, frustrating, exciting, and
highly variable hobby.
As predicted, the 33.7 -MHz signal
mentioned did fade away by the time
listened again the next morning. It
was three weeks before finally heard
the signal strong enough to warrant
some serious listening. With a little
more attention had my catch in no
time: Jefferson Township Fire DepartI
I
I
I
I
ment, Ohio.
If local communications are getting too routine and you'd like to explore how other services across the
country handle their communications, "go low" and give low -band skip
monitoring a try.
ANNUAL INDEX
J!tipular
Electronics.
1992
VOLUME 9
The Magazine for the Electronics Activist!
Gernsback Publications, Inc.
Abbreviations: (AR)Antique Radio, (C)Construction, (CB)Computer Bits, (CC)Circuit Circus, (D)Department, (DX)DX Listening, (ED)Editorial (FS)Fun Software, (HOR)Hands -On Reports, (HR)Ham Radio, (G)Gizmo (LTR)Letters, (PTR)Product Test Report, (SS)Scanner
Scene, (TT)Think Tank
3
x 3 Visual Continuity Tester (Hampton)(C)
555 -Based Alarm (Rakes)(CC)
558
and Alarm Circuits Mom Yacono)(TT)
Finale ( Yacono)(TT)
Timer, The Yacoro)(TT)
900 -MHz Digital Cordless Telephone
Tropez 900 DX (C'Brian and Scaduto)(G)
(
(
Feb 53
Feb 65
Oct 72
Nov 75
Sep 73
Jul 8
A
ABC Sports Golf: Palm Springs Open
Fathom Pictures (O'Brian and Scaduto)(G)
AC Line Monitor (Rakes)(CC)
AM'FM'Shortwave Stereo Cassette Receiver
Philips' DC777 (O Brian and Scaduto)(G)
ASAP Fax
Command Communications
(O'Brian and Scaduto)(G)
Feb
11
Jul 70
Jun
14
Aug 20
AN
Amplifier, Sansui AV-7000 (Feldman)(PTR)
Receiver, Onkyo SV70 Prc (Feldman)(PTR)
Ace Communlcatfone
AR -2800 Scanner (Saxon)(SS)
May 27
Jan 73
Mar 82
Trident CBScannerRadar
Detector (Saxon ¡(SS)
Action- Packed Issue. An (Laron)(ED)
Dec 80
Jan
2
Adjustable
Voltage Monitor (Rakes)(CC)
Voltage Current Regulator (Rakes)(CC)
Air Traffic on SW (Jensen)(DX)
Sep 70
Mar 70
Feb 74
Alarm
Circuit Yacono)(TT)
Circuits (Rakes)(CC)
Clock/Chronometer Kit. TSM 6-Digit (NOR)
Sounder Circuits (Rakes)(CC)
Alexander Popov: Russia's Radio Pioneer
(Rybak)
(
Nov
Jan
Jul
Feb
75
78
26
65
Aug 59
ALL ABOUT
Electrical Noise (Eggleston)
Jul 62
Military Electronics (Hansen)
Aug 47
Optoisolators and Optocouplers (Carr)
Oct 53
Parallel -Port Signals (Yacono)
Jan 38
Proper Input Termnation (Hansen)
Feb 58
Purpose
AllInsulation (Yacono)(TT)
Jun 70
Alpine 5951 Car CD Remote Changer
System (O'Brian and Scacuto)(G)
Jun 12
Alternate Sensor (Rakes)(CC)
Feb 65
America Power Conversion Back -UPS 250 (HORI Sep 26
Amerltron
ICP -t20 In -Rush Current Protector ( Carr)(HR) Aug 79
ICP -240 In -Rush Current Protector ( Carr)(HR) Aug
QSK -5 External 0-3K Switch ( Carr)(HR)
Aug
Answering System Telephone
AT &T 1532 (O'Brian and Scaduto)(G)
Aug
ANTENNA
Build A Precision Antenna -Rotor Comrol
System (Hockin)(C)
Jun
Design and Build Loaded Dipoles ( Carr)(HR) Mar
Dipoles, Loaded, Design andBuild (Carr)(HR) Mar
For DX ing the Low Bands An (Carr)(HR)
Nov
Quick & Dirty Quac, A (Darpree)(C)
Sep
Radio Shack Amplified VHF UHF,-FM
(Saxon)(SS)
Jun
Receiving Loop (Carr)(HR;
Jun
-Rotor Control System, Build A
Precision (Hocking)(C)
Jun
Why Not Try A Folded Dipole? ( Carr)(HR)
Jan
Wire Beams. Gain On The Cheap (Carr)
May
ANTIQUE RADIO (Ellis)(D)
Jan 76,Feb 63,Mar
Apr 65,May 66,Jun
Jul 66,Aug 68,Sep
Oct 65,Nov 65,Dec
Cleaning Up the Sky Buddy
Oct
Collectors Contest Encore
Jul
Coming: A New Restoration Project
Apr
Getting Started or the She Buddy
Jun
79
79
13
34
80
80
78
48
76
74
34
87
45
68
63
66
64
65
66
65
63
Hcusekeep Before You Troubleshoot
Sep 66
Mail Call
Mail Call!
Aug 68
Reassembling the Sky Buddy
Sky Buddy Saga. The
Theremin Plays Again, The
Mar
Dec
May
Jan
Nov
Feb
68
64
66
76
65
63
Tips and Tidbits
With The Collectors Contest Results
Archer Wireless Audio'Video Distribution System
Radio Shack (O'Brian and Scaduto)(3)
Jan 45
Artisoft Lantastic Network Starter Kit
Aug 12
AT &T Answering System Telephone
t532 (O'Brian and Scaduto)(G)
Aug 13
Audible Memo Alert (Rakes)(CC)
Sep 70
AUDIO (SEE ALSO CD)
Ace Communications' Trident
CB.!ScannerRadar Detector (Saxen)(SS)
Dec 80
Alarm ( Yacono)(TT)
Feb 68
Amplifier (Rakes)(CC)
Jar 70
AudioSource SS Threeill Pro-Logic SurroundSound Processor (O'Brian and ScadutoyG) Oct 18
Audio -Technica SM-502 Audio Myer
(Feldman)(PTR)
Dec 26
Bang & Olulsen Beosystem 2500
Music System (Feldman)(PTR)
Mar 23
Bass and Treble Booster Controls (Singmin)(C) Apr 34
Build
A 49 -MHz FM Transmitter (Becker)(C)
Nov 39
A Speaker Protector (Flynn)(C)
Mar 41
An Eight -Channel Audio Switcher
(Goebel)(C)
Dec 31
the 'Tiny Tuner" (Salas)(C)
Jun 45
Carver DPL-33 Surround -Sound
Processor/Amplifier (Feldman)(PTR)
Jul 27
Choosing and Using Audio
and Video Tape (Spiwak)
Nov 35
Citizen T530 Color LCD Pocket TV
with AM: FM Radio (O'Brian and Scaduto)(G) Jul 16
Cobra Model 39 Plus S.O.S Portable
CB Radio (O'Brian and Scaduto)(G)
Jan 47
-Frequency Meter (Rakes)(CC)
Apr 66
How to
Choose Audio Equipment (Spiwak)
Apr 35
Electronically Tune Pianos and Other
Instruments (Brown)(C)
Feb 29
Indicators and Acoustics (Martin)
May 56
Installing and Troubleshooting
Car -Audio Systems (Gipson)
Dec 35
Magnavox CD -ROM Drive'CD Player
Model CDD461RS (O'Brian and Scaduto)(G) Feb 18
Mazda RX -7 with Bose Audio
System (O'Brian and Scaduto)(G)
Sep 5
Memorex
CDX -605 Extended-Play Personal
Stereo (O'Brian and Scaduto)(G)
May 18
Triumph TS-5 Three -Piece Speaker
System (O'Brian and Scaduto)(C)
Mar 5
Onkyo SV70 Pro AudioiVideo
Receiver (Feldman)(PTR)
Jan 73
PA- System Primer. A (Allen)
Feb 55
Philips DC777 AM.'FM.'Shoriwave Stereo
Cassette Receiver (O'Brian and Scaduto)(G) Jun 14
Power Amplifier (Rakes)(CC)
Apr 66
Radio Shack Archer Wireless AN Distribution
System (O'Brian and Scaduto)(G)
Jan 45
Ramsey FX -t46 Two -Meter FM Transceiver
Kit (Kanter)
Dec 39
Sansui
Audio Note A-4 Notebook
Stereo (O'Brian and Scaduto)(G)
Model AV -7000 AV Amplifier
(Feldman)(PTR)
Sanyo MCD -Z85 Portable Audio
System (O'Brian and Scaduto)(G)
Sharp Bookshelf Stereo SystemCD Changer
Model CD -C900 (O'Brian and Scaduto)(G)
Sherwood SS -1500 Compact Stereo
System (O'Brian and Scaduto)(G)
Sony MDP-605 CD,CDVLP Player
(Feldman)(PTR)
Sound Master II PC Sound Board
Covox (O'Brian and Scaduto)(G)
Subwoofer, Build A (Whitehead)(C)
Jul
10
May 27
Dec
12
Apr
16
Mar
6
Oct 27
Technics 13S -8X306 Stereo Cassette
Deck (Feldma1)(PTR)
Sep 27
Videonics Boing Box Sound -Effects
Mixer (O'Brian and Scaduto)(G)
Mar 8
Zenith -Bose Color TV
Model ZB279zBG (O'Brian and Scaduto)(G) May 10
AudioSource SS Threell Pro-Logic Surround-Sound
Processor (O'Brian and Scaduto)(G)
Oct 18
Audio -Techrica SM -502 Audio
Mixer (Fektman) PTA)
Dec 26
AutoMap (O'Brian and Scaduto)(G)
Nov 5
AUTOMOTIVE
Alpine 5951 Car CD Remote Changer
System (O'Brian and Scaduto)(G)
Jun 12
Blaupunkt Travetoilot Vehicle Navigation
System (O'Brian and Scaduto)(G)
Jun 7
Build A
High- Energy Ignition System
For Your Ca- (Balp(C)
Sep 31,(LET)Dec 3
Voltage Adapter For Your Car (Yacono)(C) Jun 47
Circuits. More Yacono)(TT)
Apr 70
Cobra Trapshoor Solar Stealth
Radar Detector (O'Brian and Scaduto)(G)
Jun 18
Electronic Tracking Foils Car Thews (Angus) Mar 57
Installing and Troubleshooting
Car -Audio Syeems (Gipson)
Dec 35
Mazda FIX-7 with Bose Audio
System (O'Brian and Scacuto)(G)
Sep 5
Phil pS DC777 AM.'FMiShortwave Stereo
Cassette Receiver (O'Bnan and Scaduto)(G) Jun 14
Projects ( Yaconoi(TT)
Mar 73
Pace Remote Key Car -Control
System (O'Brian and Scaduto)(G)
Jun 10
Road to Tomorrow,
The (O'Brian and Scaduto)(G)
Jun 5
Assess Touch -Screen Personal Organizer
Oregon Scientific (O'Brian and Scaduto)(G)
Sep 15
(
B
Baby Monitor, Build A (Caristi)(C)
Oct 31
Back -UPS 250, Am erica Power Conversion (HOR) Sep 26
Bad Videotapes (Feldman)
Nov 31
Batun Transformer, What's A (Carr)(HR)
Feb 76
Bandpass Filer (Rakes)(CC)
Jun 67
Bang & Olufsen Beosystem 2500
Music System (Faldman)(PTR)
Mar 23
Bass and Treble Booster Controls (Singmin)(C) Apr 34
BATTERY
Charger (Yacono ((TT)
Apr 70
-Charger Probe (iacono)(TT)
Mar 73
Clips (Yacono)(T -)
Jun 70
Super -Simple NiOd-Battery
Rejuvenator (&echman)(C)
Sep 63
Beckman DM1OXL vlultimeter (HOR)
Oct 22
Big League Baseball Encyclopedia
Franklin E ectroncs (O'Brian and Scaduto)(G) Nov 16
Bit of Medite:raneai DX. A (Jensen)(DX)
Apr 74
Blaupunkt Travelpilct Vehicle Navigation
System (O Brian and Scaduto)(G)
Jun 7
Block- Heater Minder ( Yacono)(TT)
Mar 73
Boing Box Sound Effects Mixer
Videonics :O'Brian and Scaduto)(G)
Mar 8
Booster Commis, Eass and Treble (Singmin)(C) Apr 34
Bose Mazda RX -7 Audio
System (O'Brian and Scaduto)(G)
Sep 5
Brazilian DX on a Follercoaster Ride
(Jensen)(OX)
Jun 72
Breakout Box, Builc A (Yacono)(C)
May 61
Bridging Touch -Plats Sensor (Rakes)(CC)
Aug 72
Britannica Softwares Comptons Concise
Encyclopedia (O'Brian and Scaduto)(G)
Feb 13
British Bostons Interpreter II
Five Language Talking Translator
(O'Brian and Scaduto)(G)
Sep 13
BUILD &AN THE (SEE CONSTRUCTION)
-
Jan 49
Jan 31
www.americanradiohistory.com
53
All About Parallel-Port Signals tYacono)
America Power Conversion
Back -UPS 250 (HOR)
CB Radio
Cobra Model 39 Plus S.O.S.
(O'Brian and Scaduto)(G)
Jan 47
CD
Alpine 5951 Remote Changer
System (O'Brian and Scaduto)(G)
EuroSon America NSM CD3101 100-Disc
CD Changer (O'Brian and Scaduto)(G)
Gelen Systems CD Sound
Music Manager Software
(O'Brian and Scaduto)(G)
Sharp Model CD-C900 CD Changer
'Bookshelf Stereo (O'Brian and Scaduto)(G)
CD -I Player Model CD1910
Philips (O'Brian and Scaduto)(G)
CD-ROM
DeLorome Mapping's Street Atlas
USA (O'Brian and Scaduto)(G)
Grolier Electronic Encyclopedia
The New (O'Brian and Scaduto)(G)
Magnavox CD -ROM Drive CD Player Model
CDD461RS (O'Brian and Scaduto)(G)
Microsoft Bookshelf (O'Brian and Scaduto)(G)
PC Globe Electronic Atlas
(OBnan and Scaduto)(G)
PC -SIG Library (O'Brian and Scaduto)(G)
CDTV Interactive Multimedia Player
Commodore (O'Brian and Scaduto)(G)
CABLE
Jun
12
Dec 5
Dec
5
Apr
16
Feb
11
Nov
Feb
5
18
Feb 18
Feb 18
Feb 18
Feb 18
Feb 9
Jun 70
Apr 53
Rack ( Yacono)(TT)
Tester. Build A (Recklies)(C)
CAMCORDER
Canon
E40 8mm (Feldman)(PTR)
Canovision B UCS1 High -Band 8mm
(O'Brian and Scaduto)(G)
JVC GR -AXSOU Compact VHS
Feb 22
Apr
6
Sep 6
(O'Brian and Scaduto)(G)
Sony
Jan 50
CCD -F501 (O'Brian and Scaduto)(G)
CCD -FX510 8mm (O'Brian and Scaduto)(G) Oct 17
Jan 42
Canaries. The Incredible Hot (Clarke)(C)
Canon
Bmm Camcorder. Canovision 8 UCS1
Apr 6
High -Band (O'Brian and Scaduto)(G)
E40 8mm Video Camcorder (Feldman)(PTR) Feb 22
Nov 72
Capacitor -Discharge Driver (Rakes)(CC)
Oct 72
Car Alarm (Yacono)(TT)
Car-Audio Systems. Installing and
Dec 35
Troubleshooting (Gipson)
Carver DPL-33 Surround -Sound
Jul 27
Processor'Amplifier (Feldman)(PTR)
Changing Face of Russian DX. The (Jensen)(DX) Mar 78
Choosing and Using Audio and Video Tape
Nov 35
( Spiwak)
Jul 70
Circuit Grab Bag (Pakes)(CC)
Jan 78,Feb 65,Mar 70
CIRCUIT CIRCUS (Rakes)(D)
Apr 66,May 73,Jun 67
Jul 70,Aug 72,Sep 70
Oct 69,Nov 72,Dec 68
Alarm
Circuits
Sounder Circuits
Circuit Grab Bag
Electronics Potpourri
Experimenter's Test-Bench Helpers
Extended On -Time Timer
Filter Circuits
Fun With Tesla Coils
MC14538 Monostable Applications
More
High -Voltage Circuits
Intruder- Detector Circuits
54
Jan 78
Feb 65
Jul 70
Sep 70
May 73
Dec 68
Jun 67
Oct 69
Dec 68
Nov 72
Aug 72
Apr 66
Mar 70
Op-Amp Based Circuits
Regulator Applications
Citizen T530 Color LCD Pocket TV
Jul 16
with AM -FM Radio (O'Brian and Scaduto)(G(
Mar 35
Classic Induction Coil. The (Czarnik)(C)
Oct 65
Cleaning Up the Sky Buddy 1Ellis)(AR)
Jan 78
Closed-Loop Alarm ( Rakes)(CC)
Cobra
Model 39 Pius S.O.S Portable
Jan 47
CB Radio (O'Brian and Scaduto)(G)
Trapshooter Solar Stealth
Jun 18
Radar Detector (O'Brian and Scaduto)(G)
Jul 66
Collectors Contest Encore (Eilis)(AR)
Jun 22
Colorburst SV1000 Video Digitizer (HOR)
Apr 65
Coming: A New Restoration Project (Ellis)(AR)
Command Communications ASAP Fax
Aug 20
(O'Brian and Scaduto)(G)
Commodore CDTV Interactive
Feb 9
Multimedia Player (O'Bnan and Scaduto)(G)
Dec 42
Compass, Talking (Mitschke)(C)
Compton's Concise Encyclopedia
Britannica Software (O'Brian and Scaduto)(G) Feb 13
COMPUTER (SEE ALSO CD-ROM, COMPUTER BITS,
HARDWARE, SOFTWARE)
ASAP Fax. Command
Communications (O'Brian and Scaduto)(G) Aug 20
Artisoft Lantastic Network
Starter Kit (O'Brian and Scaduto)(G)
Build
a Quickie Breakout Box ( Yacono)(C)
the Printer Sentry (Yacono)(C)
the Universal RS -232 Connector
(Tarchinski (C)
May 81
Mar 59
Holograms (lovine)(C)
Negative Ion Generator (lovine)(C)
PC-Based Stepper -Motor Controller
(Antonuk)(C)
Protect Your Equipment With The
Power Block (Yacono)(C)
Quick & Dirty Quad, A (Deupree)(C)
Simple Remote -Control Analyzer
Oct 62
A (Vacuno and Spiwak)(C)
Super- Simple NiCd -Battery
Jan 38
Sep 26
Aug 12
Covox Sound Master II
PC Sound Board (O'Brian and Scaduto)(G) Jan 49
DynaPulse 200M Blood- Pressure'Pulse
Monitor, Pulse Metric
Sep 20
(O'Brian and Scaduto)(G)
Logitech Fotoman Digital
Jul 18
Camera (O'Brian and Scaduto)(G)
NEC Ultralite Ill Notebook Computer
Apr 12
(O'Brian and Scaduto)(G)
PC-Interlink File and Printer Sharing
System, Softwors (O'Brian and Scaduto)(G) Aug 21
Plug'n'Prtwer Computer Interface
May 16
Radio Shack (O'Brian and Scaduto)(G)
Printer Spooling- Hardware
Aug 40
and Software (Blechman)
Troubleshooting Parallel Connections (Vacono) Feb 41
COMPUTER BITS (HoltzmanXO)Jan 81,Feb 72,Mar 76
Apr 72,May 68,Jun 65
Jul 68,AUg 71,Sep 68
Oct 67,Nov 68,Dec 66
Aug 71
Buying Your First (or Next) PC
Computer Evolution
Integrated Software Tools
Modem Mania
Sep 68
Oct 67
Mar 76
Norton
Desktop for Windows
Utilities Version 6.0
Secret Life of a Computer Products
Reviewer, The
Sizing Up Your PC Needs
Feb 72
Jan 81
Jun 65
Jul
Mayy
Up
Word
Nov
BASIC
Dec
BASIC It
Apr
Wizardry
Concise Columbia Encyclopedia EC -7000
Franklin Electronics (O'Brian and Scaduto)(G) Mar
CONSTRUCTION
Feb
3 3 Visual Continuity Tester (Hampton)(C)
Bass and Treble Booster Controls (Singmin)(C) Apr
Build
66
6
53
34
www.americanradiohistory.com
41
Feb 37
Sep 48
Jun 38
Sep 63
Apr 38
Nov 2
PRODUCT TEST REPORTS)
Nov 31
Bad Videotapes (Feldman)
Choosing and Using Audio
Nov 35
and Video Tape (Spiwak)
CONSUMER ELECTRONICS SHOW
Oct 5
Summer (O'Brian and Scaduto)(G)
May 5
Winter (O'Brian and Scaduto)(G)
Convenience Light for Remote Controls
Aug 37
(Spiwak)(C)
Cool Oldies Jukebox, PIMA
Feb 11
(O'Brian and Scaduto)(G)
Cop Talk: Understanding Police
Jan 61
Communications (Quarantietlo)
Cordless-Telephone Lock,
Build A (Sokolowski)(C)
Jul 44,(LET) Oct 3
Courier Procom UHF -FM Transceiver (Saxon)(SS) Sep BO
Covox Sound Master II PC Sound
Jan
Board (O'Brian and Scaduto)(G)
Create a High- Voltage Miniature
May
Tamado (Ford)(C)
Cross -Reference Software, Philips ECG (HOR) Dec
Nov
Current injector, One Amp (Johnson)(C)
49
55
62
46
D
Aug 65
Mar 70
DC Motor Controller ( Rakes)(CC)
DIT Telephone Security Device,
Jul 8
Phone Guard (O'Brian and Scaduto)(G)
Jan 85.Feb 74,Mar 78
DX LISTENING (Jensen)(D)
dB or Not dB (Honeycutt)
Apr 74,May 78,Jun 72
Jul 75,Aug 77,Sep 76
Oct 75,Nav 80,Dec 76
A
Nov 39
49-MHz FM Transmitter (Becker)(C)
Oct 31
( Caristi)(C)
Baby
May 61
Breakout Box (Yacono)(C)
Cable Tester ( Recklies)(C)
Aprr 53
Dec
Compass, Talking ( Mitschke)(C)
Jul 44
Cordless-Telephone Lock (Sokolowski)(C)
Jul 41
Geiger Counter (lovine)(C)
High- Energy Ignition System
Sep 31,(LET)Dec 3
For Your Car (Bail)(C)
Holiday -Light Tester (Yacono and Spiwak)(C) Dec 59
Low -Cost Morse -Code Transmitter (Lisle)(C) Aug 45
Miniature Tracking Transmitter (Vollono)(C) Jun 29
Nov 46
One-Amp Current Injector ( Johnson)(C)
Oct 39
Personal Message Recorder (Williams)(C)
Pop Up Outdoor Lighting
May 38
System (Schmiedeberg)(C)
Portable 2 -MHz Frequency Counter
Jul 53
( Caristi)(C)
Precision Antenna -Rotor Control
Jun 34
System (Hocking)(C)
Precision Darkroom Timer
Aug 53
(Graf and Sheets)(C))
May 61
Quickie Breakout Box ( Yacono)(C)
Soldering -Iron Controller
May 53
(Yacono and Spiwak)(C)
Oct 58
Sonic Kaleidoscope (Ray)(C)
Mar 41
Speaker Protector (Flynn)(C)
Jan 31
Subwoofer (Whitehead)(C)
Dec 53
Voice Disguiser (Voltono)(C
Nov 53
Voice-Mail Alert (O'Kelley (C)
Voltage Adapter For Your Car ( Yacono)(C) Jun 47
Build An
Automatic Porch -Light Control (Ponting)(C) Mar 46
Automatic Power Switch
Nov 43
For Your TV (Vaughn)(C)
Eight -Channel Audio Switches (Goebel)(C) Dec 31
(Caristi)(C)
Sep 39
Emergency Telephone Dialer
Build The
Jun 45
"Tiny Tuner (Salas)(C)
Sep 53
Idiot Box (Head)(C)
Mat 59
Printer Sentry ( Yacono)(C)
(C)
Oct 62
(Tarchinski
RS
Connector
Universal
-232
The
Mar 35
(Czarnik)(C)
Classic Induction Coil,
Convenience Light for Remote
Aug 37
Controls (Spiwak)(C)
Create a High- Voltage Miniature
May 55
Tornado ( Ford)(C)
Electric Waves and the Hertz
Oct 45
(Czarnik)(C)
Oscillator
Oct 42
Electromagnetic Ring Launcher (Voliono)(C)
Enlarging Light Meter for Photographic
Apr 31
Printing, An (Graf and Sheets)(C)
Experiment With Plasma Acoustics (lovine)(C) Oct 37
Good Vibrations Printed -Circuit Board
Apr 62
Workstation (Yacono)(C)
How To Electronically Tune Pianos
Feb 29
and Other Instruments (Brown)(C)
Jan 42
Incredible Hot Canaries, The ( Clarke)(C)
Make Your Own
May 31
High-Voltage Capacitors (Chartton)(C)
Jun
CONSUMER ELECTRONICS (SEE ALSO GIZMO,
66
12
Jan 29
Rejuvenator (Blechman)(C)
Telephone Ring Converter, The (Poeth)(C)
Consumer Alert (Laron)(ED)
68
72
Aug 31,Sep 43
Air Traffic on SW
Bit of Mediterranean DX, A
Brazilian DX on a Roltercoaster Ride
Changing Face of Russian DX, The
Exploring the Lower Shortwave Bands
Into The Mailbag
Feb 74
Apr 74
Jun 72
Mar 78
Oct 75
Sep 76
Jul 75
Just' 'Chill" Out
Jan 85
Programming For SWL's
Radio Polonia is Gone; Polish Radio is Back Aug 77
Nov
8C
Shortwave Revival, The
Dec 7E
United Nations Radio
WWV and WWVH Offer More Than You Think! May 76
Data Discman Model DDt -EX, Sony
Feb 12
(O'Brian and Scaduto)(G)
Daewoo DVP -1060N Video Cassette Player
Jun 2E
(Feldman)(PTR)
Darkroom Timer,
Aug 5
Build A Precision (Graf and Sheets)(C)
David Hughes: Electromagnetic Pioneer (Rybak) Nov 6C
Delayed Alarm Alarm/ Sounder Circuits
Feb 65
( Rakes)(CC)
DeLorome Mapping's Street Atlas USA
Nov 5
(O'Brian and Scaduto)(G)
Mar 80
Design and Build Loaded Dipoles (Carr)(HR)
Deskmate Automatic House Software
Radio Shack (O'Brian and Scaduto)(G)
May 16
Digital
Frequency Counter, Heathkit IM -2410 (HOR)
Multimeters, Fluke Series 10 (HOR))
Sawtooth Generator. The (CarrXHR)
Dipoles, Loaded, Design and Build (Carr((HR)
Do You Compute? Yacono)(TT)
Drive -Through Sermons (Saxon)(SS)
Driver Circuit ( Rakes)(CC)
Dual -Tone Sounder ( Rakes)(CC)
Duofone Outgoing Call Restnctor
Radio Shack (O'Brian and Scaduto)(G)
DynaPulse 200M Computerized Blood-Pressure
Monitor, Pulse Metric (O'Brian and Scaduto)(G)
(
May 22
Apr 28
May 76
Mar 80
Dec 72
Nov 82
Nov 72
Feb 65
Mar 13
Pulse
Sep 20
E
EDITORIAL (Laron)
Action -Packed Issue, An
Consumer Alert
Electronics and the Automobile
End of a Legend. The
Get Up, Get Active!
HDTV Update
Importance of Perspective. The
Jan 2,Feb 2,Mar
Apr 2,May 2,Jun
Jul 2,Aug 2,Sep
Oct 2,Nov 2, Dec
Jan
2
2
2
2
2
Nov 2
Jun
Aug
Apr
Mar
2
Sep
2
2
2
2
111
Made In Japan
Multimedia Madness
Old Gear, New Lives
Positioning Ourselves
Edmund Scientific Optivisor
Magnifying Glass (Carr)(HR)
Eight -Channel Audio Switcher (Goebel)(C)
Electric Waves and the Hertz
Oscillator (Czarnik)(C)
Electrical Noise, All About (Eggleston)
Electricity and Medicine in the
19th Century (Czernik)
May 2
Feb 2
Oct 2
Jul
2
Aug 79
Dec
31
Oct 45
Jul 62
Sep 58
Electromagnetic.
Electromagnetic Ring Launcher (Vollono)(C)
Oct 42
David Hughes: Electromagnetic
Pioneer (Rybak)
Nov 60
Electronic Tracking Foils
Car Theives (Angus)
Mer 57,(LET) Jul 3
Electronically Tune Pianos and Other
Instruments, How To (Brown)(C)
Feb 29
ELECTRONICS LIBRARY (D)
Jan 6,Feb 80,Mer 84
Apr 80,May 82,Jun 78
Jul 82,Aug 84,Sep 82
Oct 83,Nov 84,Dec 82
ELECTRONICS
and the Automobile (Laron)(ED)
Jun 2
Potpourri ( Rakes)(CC)
Sep 70
Technicians Day (Steckler)
Apr 40
Elenco Micro-Master MM -8000
Basic Systems Course (HOR)
Aug 26
Emergency Telephone Dialer, Build An ( Caristi)(C) Sep 39
End of a Legend, The (Laron)(ED)
Aug 2
Enlarging Light Meter for Photographic
Printing. An(Grat and Sheets)(C)
Apr 31
Etch Your Own PC Boards (Young)
Jan 68
EuroSon America's NSM CD3101 100 -Disc
CD Changer (O'Brian and Scaduto)(G)
Dec 5
Experiment With Plasma Acoustics (lovine)(C)
Oct 37
Experimenters Test -Bench Helpers ( Rakes)(CC) May 73
Exit Delay (Rakes)(CC)
Aug 72
Exploring the Lower Shortwave
Bands (Jensen)(DX)
Oct 75
Extended On -Time Timer Rakes)(CC)
Dec 68
(
F
FACTCARDS (0)
Jan S1,Feb 49,Mar
Apr 49,May 49,Jun
Jul 49,Aug 49,Sep
Oct 49,Nov 49,Dec
53
48
49
49
Fathom Pictures' ABC Sports Golf:
Palm Springs Open (O'Brian and Scaduto)(G) Feb 11
Filter Circuits ( Rakes)(CC)
Jun 67
Fluke Series -10 Digital Multimeters (HOR)
Apr 28
FM Transmitter, Build a 49 -MHz (Becker)(C)
Nov 39
Folded Dipole, Why Not Try A? (Cerr)(HR)
Jan 87
Fotoman Digital Camera for Computers
Logitech (O'Brian and Scaduto)(G)
Jul 18
Franklin Electronics
Big League Baseball
Encyclopedia (O'Brian and Scaduto)(G)
Concise Columbia
Encyclopedia (O'Brian and Scaduto)(G)
Frequency Counter, Portable 2 -MHz (Caristi)(C)
Fridge Alarm (Yacono)(TT)
Fun Software (Blechman)(D)
Real REC, A
Nov 16
Mar 12
Jul 53
Nov 75
Jan 83
Jan 83
Fun With
Analog Tachometer Circuits (Carr)
Op -Amps (Yacono)(TT)
Testa Coils Rakes)(CC)
Fungi TVCP 9T 9 -Inch TV.'
Video Cassette Player (Feldman)(PTR)
Function- Generator Kit, TSM (HOR)
Funexs Motion- Converter Exercise-Gear
Interface (O'Brian and Scaduto)(G)
(
Jul 59
Jan 22
Oct 69
Nov 27
Nov 22
Jan 46
G
GPS
Navigation System, The Fenton)
Receiver, Sony Pyxis (O Brian and Scaduto)(G)
Geiger Counter, Build A (lovine)(C)
Gefen Systems' CD Sound Music Manager
Software (O'Brian and Scaduto)(G)
Get Up, Get Active! (Laron)(ED)
Jul
31
Jut 5
Jul 41
Dec
5
Apr
2
Getting
Started on the Sky Buddy (Ellis)(AR)
Jun 83
to the Bottom of the Mailbag (Saxon)(SS)
May 80
Give Your Handheld A Boost! (Saxon)(SS)
Jun 76
GIZMO (O'Brian and Scaduto)(D) Jan 45,Feb 4,Mar 5
Apr S,May 5,Jun 5,(LET)Aug 3
Jul 5,Aug 5,Sep 5,(LET)Dec
Oct 5,Nov 5,Dec
Alpine 5951 Car CD Remote Changer System Jun
Artisoft Lantastic Network Starter Kit
Aug
AT &T Answering System Telephone 1532
Aug
3
5
12
12
13
AudioSource SS Three/II Pro-Logic
Surround -Sound Processor
Blaupunkt Travelpifot Vehicle Navigation
System
Bose Mazda RX-7 Audio System
Britannica Software's Compton's Concise
Encyclopedia
British Boston's Interpreter II Five- Language
Talking Translator
Canon Bmm Camcorder, Canovision 8
UCS1 High -Band
Citizen T530 Color LCD Pocket TV
with AM'FM Radio
Oct
18
Jun 7
Sep
5
Feb 13
Sep 13
Apr 6
Jul 16
Cobra
Model 39 Plus S.O.S Portable
CB Radio
Jan 47
Trapshooter Solar Stealth
Radar Detector
Jun 18
Command Communications' ASAP Fax
Aug 20
Commodore CDTV Interactive Multimedia
Player
Feb 9
Consumer Electronics Show
Summer 1992
Oct 5
Winter 1992
May 5
Jan 49
Covox Sound Master II PC Sound Board
Nov 5
DeLorome Mapping s Street Atlas USA
DIT Telephone Security Device, Phone Guard Jul 8
EuroSon America's NSM CD3t01 100 -Disc
CD Changer
Dec 5
Fathom Pictures' ABC Sports Golf:
Feb 11
Palm Springs Open
Franklin Electronics
Nov 16
Big League Baseball Encyclopedia
Concise Columbia Encyclopedia
Mar 12
Funex's Motion -Converter Exercise -Gear
Interface
Jan 46
Gefen Systems CD Sound Music Manager
Software
Dec 5
Grolier Electronic Encyclopedia, The New Feb 5,Feb 18
Home -Office Round -Up
(O'Brian and Scaduto)(G)
Aug 5
Instant Replay's Image Translator
Standards Converting VCR
Nov 12
JVC GR -AX50U Compact VHS Camcorder
Sep 6
Logitech Fotoman Digital Camera
for Computers
Jul 18
Magnavox's CD -ROM DrivetD
Feb 18
Player Model CDD46IRS
Mazda RX -7 with Bose Audio System
Sep 5
Memorex
CDX -605 Extended -Play Personal Stereo May 18
Triumph TS-5 Three -Piece Speaker System Mar 5
Microsoft
Bookshelf
Feb 18
Multimedia Beethoven: The Ninth Symphony Feb 20
Multi- Link's SR2 Selective Ring Processor
Aug 15
Multimedia Madness! (O'Brian and Scaduto)(G) Feb 5
NEC Ultralite III Notebook Computer
Apr 12
Oregon Scientific Axxess Touch-Screen
Personal Organizer
Sep 15
Panasonic PT-10L Compact Video Projector
Apr 5
PC Globe Electronic Atlas
Feb 18
PC Maps
Nov 5
PC -SIG Library
Feb 18
Philips
Feb 11
CD -I Player, Model CD1910
DC777 AM /FM /Shortwave Stereo
Jun 14
Cassette Receiver
Feb 11
PIMA Cool Oldies Jukebox
Feb 9
Ps gnosis Lemmings
Pulse Metrics DynaPulse 200M
Sep 20
Blood -Pressure/Pulse Monitor
Race's Remote Key Car -Control System
Jun 10
Radio Shack
Archer Wireless AV Distribution System
Jan 45
Deskmate Automatic House Software
May 16
Duofone Outgoing Call Restrictor
Mar 13
Plug nPower Computer Interface
May 16
Pocketvision-26 LCD Color TV
Apr 8
Road to Tomorrow, The
Jun 3
Rolodex Personal Planner Model EO-100
Oct 20
Sansui Audio Note A-4 Notebook Stereo
Jul 10
Sanyo
MCD -Z85 Portable Audio System
Dec 12
Pulse Meter HRM -5520 Heart -Rate Monitor Jan 48
Sharp Bookshelf Stereo System CD
Apr 16
Changer Model CD -C900
Sherwood SS -1500 Compact Stereo System
Mar 6
Sottworx PC Interlink File and Printer
Aug 21
Sharing System
Sole Control Universal Replacement
May 12
Remote Control
Sony
CCD -F501 Video Camcorder
Jan 50
Oct 17
CCD -FX510 Bmm Camcorder
Feb 13
Data Discman Model DD1 -EX
Dec 7
EV -S3000 Hi8 VCR
Pyxis GPS Receiver
Jul 5
Tandy 2500SXi20 Multimedia PC
Feb 20
Tropez 900 DX Digital 900 -MHz
Cordless Telephone
Jul 8
Universal Electronics One For All 4
Home Control Remote Control
Nov 20
Videonics
Boing Box Sound- Effects Mixer
Mar 8
Video Ttlemaker
Sep 12
VidiPax International Video Conversion Service Nov 13
Whistler Interstate Tnpmate
Highway Travel Planner
Zenith -Bose Color TV Model ZB2794BG
Apr
10
May 10
Global Positioning System
Jul
GPS Navigation System, The (Fenton)
GPS Receiver
Sony Pyxis (O'Brian and Scaduto)(G)
Good Vibrations Printed-Circuit Board
Workstation (Yacono)(C)
Grand Piano Kit, The OWI (HOR)
Grolier Electronic Encyclopedia,
The New (O'Brian and Scaduto)(G)
Guglielmo Marconi (Rybak)
31
Jul
5
Apr 62
Jan 72
Feb 9,Feb 16
Apr 43
H
HDTV Update ÍLaron)(ED)
HAM RADIO (Carr)(D)
Mar 2
Jan 87,Feb 76,Mar 80
Apr 76,May 76,Jun 74
Jul 77,Aug 79,Sep 78
Oct 78,Nov 78,Dec ??
Antenna For DX ing the Low Bands, An
Nov 78
Design and Build Loaded Dipoles
Mar 80
Digital Sawtooth Generator, The
May 76
OI Sol -Friend or Foe
Jul 77
Receiving Loop Antennas
Jun 74
Some
More Spectrum Analyzer Stuff
Oct 78
New Products and Some Questions
Answered
Aug 79
Thoughts on Radio Propagation
Apr 76
Tools for Eimers and Elmees
Sep 78
Whatt A Balun Transformer?
Feb 76
Why Not Try A Folded Dipole?
Jan 87
Handheld That Won't Break the Bank,
A (Saxon)(SS)
Aug 82
HANDS-ON REPORT (D)
Jan 72,Feb 61,Mar 65
Apr 28,May 22,Jun 22
Jul 26,Aug 28,Sep 26
Oct 22,Nov 22,Dec 62
America Power Conversion Beck-UPS 250
26
Beckman DM10XL Multimeter
Oct 22
Colorburst SV1000 Video Digitizer
Jun 22
Elenco Micro -Master MM -8000 Basic
Systems Course
Aug 26
Fluke Series -10 Digital Multimeters
Apr 28
Heathkit IM -2410 Digital Frequency Counter May 22
Mental Automation SuperCAD Electronics
Design Software
Mar 65
OWI Grand Piano Kit. The
Jan 72
Philips ECG Cross -Reference Software
Dec 62
Protel Schematic Circuit- Design Software
Feb 61
TOM
Function- Generator K0
6 -Digit Alarm Clock.'Chronometer Kit
HARDWARE
Buying Your First (or Next) PC (Holtzman)(CB)
Elenco Micro-Master MM -8000 Basic
Systems Course (HOP)
America Power Conversion,
Back -UPS 250 (HOR)
Hayes Microcomputer Products,
Optima 96 (HOLzman)(CB)
Headlights Reminder (Yacono)(TT)
Heathkit 1M -2410 Digital
Frequency Counter (HOR)
Nov 22
Jul 26
Aug
71
Aug 26
Sep 28
Mar 76
Mar 73
May 22
Hertz Oscillator, The,
and Electric Waves (Czamik)(C)
Oct 45
High- Energy Ignition System For
Your Car (Ball)(C)
Sep 31,(LET)Dec 3
High -Power Alarm Driver ( Rakes)(CC)
Jan 78
High-Voltage
Capacitors,
Make Your Own (Chariton.)(C) May
Circuits, More (Rakes)(CC)
Miniature Tornado, Build A (Ford)(C)
HISTORY
Alexander Popov:
Russia's Radio Pioneer (Rybak)
31,
(LET) Aug 3
Nov 72
May 55
Aug 59
David Hughes:
Electromagnetic Pioneer (Rybak)
Nov 60
Electric Waves and the
Hertz Oscillator (Czarnik)(C)
Oct 45
Electricity and Medicine in the
19th Century (Czernik)
Sep 58
Guglielmo Marconi (Rybak)
Apr 43
Magnetic Light ( Czarnik)
Apr 57
Holiday -Light Tester (Yacono and Spiwak)(C)
Dec 59
Holograms. Make Your Own (lovine)(C) Aug 31,Sep 43
HOME CONTROL
Radio Shack
Deskmate Automatic House
Software (O'Brian and Scaduto)(G)
May 16
Plug'n'Power Computer
Interface(O'Brian and Scaduto)(G)
May 16
One For All 4 Universal Remote
Control (O'Brian and Scaduto)(G)
Nov 20
HOME OFFICE
AT &T Answering System Telephone
1532 (O'Brian and Scaduto)(G)
Aug 13
Command Communications
Artisoft Lantastic Network
Starter Kit (O'Brian and Scaduto)(G)
Aug 12
ASAP Fax (O'Brian and Scaduto)(G)
Aug 20
55
www.americanradiohistory.com
Home -Office Round-Up
Aug 5
(O'Brian and Scaduto)(G)
Multi -Link SR2 Selective Ring
Aug 15
Processor (O'Brian and Scaduto)(G)
Softworx PC-Interlink File and Printer Sharing
Sharing System (O'Brian and Scaduto)(S) Aug 21
Housekeep Before You Troubleshoot! (Ellis)(AR) Sep 66
How to
Apr 35
Choose Audio Equipment (Spivak)
Electronically Tune Pianos and Other
Feb 29
Intruments (Brown)(C)
Hughes, David: Electromagnetic Pioneer (Rybak) Nov 60
IR
Jan 22
Decoder (Yacono)(TT)
Jan 22
Op -Amp (Yacono)(TT)
Teats
Certification
ISCET
Apr 40
Electronics Technicians Day (Steckler)
Sep 53
Idiot Box, Build the (Head)(C)
Ignition System For Your Car,
Sep 31
Build a High -Energy (Ball)(C)
Image Translator Standards Converting VCR,
Nov 12
Instant Replay (O'Brian and Scaduto)(G)
Sep 2
Importance of Perspective, The (Laron)(ED)
Incredible Hot Canaries, The (Clarke)(C) Jan 42,(LET)
Apr
Induction Coli. The Classic (Czarnik)(C)
Input Termination, All About Proper (Hansen)
In-Rush Current Limiter ( Rakes)(CC)
Installing and
Maintaining Telephone Systems (Young)
Troubleshooting Car -Audio Systems (Gipson)
Instant Replay's Image Translator
Standards Converting VCR
(O'Brian and Scaduto)(G)
Integrated Software Tools ( Holtzman)(CB)
Interpreter Five -Language Talking Translater
British Boston (O'Brian and Scaduto)(G)
Interstate Trípnate Highway Travel Planner
Whistler (O'Brian and Scaduto)(G)
Into The Mailbag (Jensen)(DX)
Intruder -Detector Circuits, More Rakes)(CC)
Intrusion -Indicator Circuit (Yacono)(TT)
3
Mar 35
Feb 58
Mar 70
Nov 55
Dec 35
Nov 12
Oct 67
11
(
Sep 13
Apr 10
Sep 76
Aug 72
Oct 72
J
Memorex
CDX -805 Extended -Play
Personal Stereo (O'Brian and Scaduto)(G)
Dec 45
Sep
5
Sep 58
Apr 74
May 18
Model 87 Video Cassette Recorder
Apr 26
(Feldman)(PTR )
Model 153 8mm Camcorder (Feldman)(PTR) Aug 26
Triumph TS -5 Three-Piece Speaker
Mar 5
System (O'Brian and Scaduto)(G)
Mental Automation SuperCAD Electronics
Mar 65
Design Software (HOR)
Micro- Master MM-8000 Basic Systems
Aug 26
Course, Elenco (HOR)
May 70
Microctips and More ( Yacono)(TT)
Jul 70
Microphone Amplifier (Rakes)(CC)
Microsoft
Feb 18
Bookshelf (O'Brian and Scaduto)(G)
Multimedia Beethoven
Aug 71
(Hottzman)(CB)
Feb 20
(O'Brian and Scaduto)(G)
Word for Windows 2.0
( Holtzman)(CB)
Oct 67,Nov 68,Dec 66
Apr 72
Word for Windows ( Holtzman)(CB)
Aug 47
Military Electronics, All About (Hansen)
Miniature Tracking Transmitter,
Jun 29
Build A (Vollono)(C)
Mar 76
Modem Mania ( Holtzman)(CB)
Jul 70
Modified Squarewave Oscillator ( Rakes)(CC)
Monitoring
Sets (Saxon)(SS)
Remote News Crews (Saxon)(SS)
More
558 and Alarm Circuits ( Yacono )(TT)
Automotive Circuits ( Yacono)( )
Fun With Op -Amps (Yacono)(TT)
High-Voltage Circuits (Rakes)(CC)
Intruder-Detector Circuits ( Rakes)(CC)
Tips (Yacono)(TT)
Morse-Code Transmitter,
Build A Low-Cost (Lisle)(C)
Motion-Converter Exercise -Gear Interface
Funex (O'Brian and Scaduto)(G)
Sep 6
Jul 75
K
Oct 58
Dec 2
Kaleidoscope, Sonic (Ray)(C)
Kit Building Lives (Laron)(ED)
L
LCD Technology (Katznelson)
Jun
Lamp-Switching Circuit (Rakes)(CC)
Lantastic Network Starter Kit
Dec 68
Aug
61
12
Feb 9
Jan 4,Feb 3,Mar 3
Apr 3,May 3,Jun 3
Jul 3,Aug 3,Sep 3
Oct 3,Nov 3,Dec 3
Light
-Dependent Sensor (Rakes)(CC)
Sources For Projects and Instruments (Carr)
Sources, Solid -State (Cart)
Lights -On Reminder (Yacono)(TT)
Logical Turn Signal ( Yacono)(TT)
Logitech Fotoman Digital Camera
for Computers (O'Brian and Scaduto)(G)
Long -Period Monostabe ( Yacono)(TT)
Look at the Mailbag, A (Saxon)(SS)
Low-Frequency Antenna (Carr)(HR)
Low-Level Sounder (Rakes)(CC)
Mar 82
Dec 80
Oct 72
Apr 70
Feb 68
Nov 72
Aug 72
Jun 70
Aug 45
Jan 46
Jan 78
-Loop Parallel Alarm ( Rakes)(CC)
Oct 72
-Point Intrusion Detector ( Yacono)(TT)
Multi -Links SR2 Selective Ring
Aug 15
Processor (O'Brian and Scaduto)(G)
MULTIMEDIA
Britannica Software Compton's Concise
Feb 13
Encyclopedia (O'Brian and Scaduto)(G)
Commodore CDTV Interactive
Multimedia Player (O'Brian and Scaduto)(G) Feb 9
Fathom Pictures ABC Sports Golf:
Palm Springs Open (O'Brian and Scaduto)(G) Feb 11
Feb 2
Madness (Laron)(ED)
Feb 5
Madness! (O'Brian and Scaduto)(G)
Player
Magnavox CO-ROM Drive/CD
Model CDD461RS (O'Brian and Scaduto)(G) Feb 18
Microsoft
Aug 71
Beethoven (Holtzman)(CB)
Beethoven: The Ninth Symphony
Feb 20
(O'Brian and Scaduto)(G)
Philips CD -I Player
Feb 11
Model CD1910 (O'Brian and Scaduto)(G)
Software Roundup (O'Brian and Scaduto)(G) Mar 14
Tandy 2500 SX -20 PC
Feb 20
Oct 22
(O'Brian and Scaduto)(G)
Multimeter, Beckman DM1OXL (HOR)
Aug 72
Mar 49
Jun 31
Apr 70
Mar 73
Jul
18
Oct
Feb
Nov
Feb
72
78
78
65
M
MC14538 Monostarte Applications ( Rakes)(CC) Dec 68
May 2
Made In Japan ( Laron)(ED)
Magnavox's CD-ROM Drive /CD Player
Model CDD461RS (O'Brian and Scaduto)(G) Feb 18
Apr 57
Magnetic Light (Czarnik)
Aug 68
Mail Call (Eilis)(AR)
Mar 68
Mail Call! (Ellis)(AR)
Make Your Own
High- Voltage
May 31,(LET) Aug 3
Capacitors (Chartton)(C)
Aug 31,Sep 43
Holograms (lovine)(C)
N
Jun 53
NE602 Circuits One -Chip Receiver (Carr)
NEC Ultralite III Notebook
Apr 12
Computer (O'Brian and Scaduto)(G)
NSM C03101 100 -Disc CD Changer
Dec 5
Scaduto)(G)
EuroSon America (O'Brian and
Jul 31
Navigation System, The GPS (Fenton)
Jan 29
Negative Ion Generator (lovine)(C)
Jan 89
New Kid on the Block (Saxon)(SS)
Jan 14,Feb 86,Mar 88
NEW PRODUCTS (D)
Apr 83,May 85,Jun 81
Jul 84,Aug 86,Sep 88
Oct 85,Nov 86,Dec 85
NiCd -Battery Rejuvenator,
Super-Simple (Blechman)(C)
No -Doze Alarm ( Rakes)(CC)
Non -Inverting Amplifier (Yacono)(TT)
o
Apr 43
Multi
JVC GR -AX50U Compact VHS
Camcorder (O'Brian and Scaduto)(G)
Just "Chili" Out (Jensen)(DX)
Arttsoft (O'Brian and Scaduto)(G)
nosis Ltd.
Lemmings, P
(O'Brian and Scaduto)(G)
LETTERS (D)
Making the Connection (Carr)
Marconi, Guglielmo (Rybak)
Mazda RX7 with Bose Audio
System (O'Brian and Scaduto)(G)
Medicine, and Electricity. in the 19th Century
(Czamìk)
Mediterranean DX, A Bit of (Jensen)(DX)
Sep 63
Dec 68
Jan 22
Norton
Desktop for Windows (Holtzman)(CB)
Utilities Version 6.0 ( Holtzman)(CB)
Not Another Op -Amp Article! (Dougherty)
Notch Filter ( Rakes)(CC)
Null -Modem Cable ( Yacono)(TT)
www.americanradiohistory.com
Feb 72
Jan 81
Dec 57
Jun 67
Dec 72
Of
Sol- Friend or Foe
(Carr)(HR)
Old Gear, New Lives ( Laron)(ED)
On -Delay Monostabe ( Yacono)(TT)
One Chip Receiver Front-End, A (Carr)
-Way Voice-Activated Intercom ( Rakes)(CC)
Onkyo SV70 Pro Audio/Video
Receiver (Feldman)(PTR)
Jul 77
Oct 2
Oct 72
Jun 53
Apr 66
Jan 73
Op-Am
rtie, Not Another (Dougherty)
Based Circuits ( Rakes)(CC)
Dec 57
Apr 66
Op -Amps
Fun With ( Yacono)(TT)
More Fun With (Yacono)(TT)
Jan 22
Feb 68
Optima 96, Hayes Microcomputer
Products ( Holtzman)(CB)
Mar 78
Optoisolators and Optocouplers. All About (Carr) Oct 53
Oregon Scientific Axxess Touch -Screen Personal
Sep 15
Organizer -(O'Brian and Scaduto)(G)
Oscilloscopes, Buyer's Guide to Low -Cost ( Spiwak) Jul 35
Outdoor Lighting System, Build A
Pop -Up (Schmiedeberg)(C)
May 38,(LET) Aug 2
OWI Grand Piano Kit, The (HOR)
Jan 72
P
PA- System Primer, A (Allen)
Feb 55
PCBased Stepper-Motor
Jun 41,(LET)Sep 3
Controller (Antonuk)(C)
Board Workstation,
Apr 62
The "Good Vibrations- (Yacono)(C)
Jan 68
Boards, Etch Your Own (Young)
Globe Electronic Atlas
Feb 18
(O'Brian and Scaduto)(G)
Interlink File and Printer Sharing System
Aug 21
Softworx (O'Brian and Scaduto)(G)
Nov 5
Maps (O'Brian and Scaduto)(G)
Feb 18
-SIGLibrary (O'Bran and Scaduto)(G)
Panasonic PT-10L Compact
Apr 5
Video Projector (O'Brian and Scaduto)(G)
Parallel
Connections, Troubleshooting ( Yacono)
-Loop Alarm ( Rakes)(CC)
-Port Signals, All About (Yacono)
Personal
Message Recorder, Build A (Wìlliams)(C)
Planner Model E0-100,
Rolodex (O'Brian and Scaduto)(G)
Stereo, Memorex Extended
Play (O'Brian and Scaduto)(G)
Feb 41
Jan 78
Jan 38
Oct 39
Oct 20
May 18
Philips
CD-I Player,
Model CD1910 (O'Brian and Scaduto)(G)
DC777 AM /FM /Shortwave Stereo Cassette
Receiver (O'Brian and Scaduto)(G)
ECG Cross -Reference Software (HOR)
PHONE (SEE ALSO TELEPHONE)
Guard Telephone Security Device,
DTI (O'Brian and Scaduto)(G)
Line "Tester- ( Yacono)(TT)
-Line Interlace (Yacono)(TT)
-Use Indicator (Yacono)(TT)
Feb
11
Jun 14
Dec 62
Jul 8
Aug 75
Sep 73
Sep 73
PHOTOGRAPHY
Build A Precision Darkroom Timer
Aug 53
(Graf and Sheets)(C)
Enlarging Light Meter for Photographic Printing,
Apr 31
An (Graf and Sheets)(C)
Logitech Fotoman Digital Camera
Jul 18
for Computers (O'Brian and Scaduto)(G)
Plasma Acoustics, Experiment With ( lovine)(C) Oct 37
Plug'n'Power Computer Interface
May 16
Radio Shack (O'Brian and Scaduto)(G)
Apr 70
Polarity Indicator ( Yacono)(TT)
Oct 78
Poor Man$ Spectrum Analyzer (Carr)(HR)
Popov, Alexander:
Aug 59
Russia's Radio Pioneer (Rybak)
Porch -Light Control,
Build An Automatic (Ponting)(C)
Mar 46
Positioning Ourselves ( Laron)(ED) Jul 2,(LET) Sep 3
Power
Block, Protect Your Equipment
Feb 37,(LET)May 3
With The (Yacono)(C)
May 73
Supply Rakes)(CC)
Nov 43
Switch For Your TV, Automatic (Vaughn)(C)
Printer
Mar 59
Sentry, Build the (Yacono)(C)
Spooling- Hardware and Software (Blechman) Aug 40
PIMA Cool Oldies Jukebox
Feb 11
(O'Brian and Scaduto)(G)
Jan 73,
PRODUCT TEST REPORTS (FeldmanXD)
Feb 22,Mar 23
Apr 26,May 27,Jun 26
Jul 27,Aug 26,Sep 27
Oct 27,Nov 27,Dec 26
Dec 26
Audlo- Technica Audio Mixer SM -502
Bang & Olutsen Beosystem 2500 Music System Mar 23
Feb 22
Canon E40 8mm Video Camcorder
Carver DPL-33 Surround -Sound
Processor /Amplifier
Daewoo DVP-1060N Video Cassette Player
Funai TVCP 9T 9 -Inch TV /Video Cassette
Sole Control Universal Replacement
Jul 27
Jun 26
Player
Nov 27
Memorex
Model 87 Video Cassette Recorder
Apr 26
Model 153 8mm Camcorder
Aug 26
Onkyo SV70 Pro AudioNideo Receiver
Jan 73
Sansui Model AV-7000 NV
Amplifier
May 27.(LET)Oct 3
Sony MDP -605 CDrCDV LP Player
Oct 27
Technics RS -8X606 Stereo Cassette Deck
Sep 27
Programming For SWL's (Jensen)(DX)
Jan 85
Protect Your Equipment With
The Power Block (Yacono)(C)
Feb 37,(LET)May 3
Protel Schematic Circuit -Design Software (HOR) Feb 61
Psygnosis' Lemmings (O'Brian and Scaduto)(G) Feb 9
Public -Address Systems
PA- System Primer, A (Allen)
Feb 55
Pulse Meter HRM -5520 Heart-Rate Monitor
Sanyo (O'Brian and Scaduto)(G)
Jan 48
Pulse Metric's DynaPulse 200M Blood-Pressure/Pulse
Monitor (O'Brian and Scaduto)(G)
Sep 20
Q
SR2 Selective Ring Processor
Multi -Link (O'Brian and Scaduto)(G)
Sansui
Audio Note A -4 Notebook
Stereo (O'Brian and Scaduto)(G)
Model AV-7000 kV
Amplifier ( Feldman)(PTR)
Sep 48
R
RS -232 Connector, Universal (Tarchinski)(C)
Race Remote Key Car -Control
System (O'Brian and Scaduto)(G)
Oct 62
Jun
10
RADAR DETECTOR
Ace Communications Trident
(
Saxon)(SS)
Dec 80
Stealth (O'Brian and Scaduto)(G)
Jun 18
RADIO (SEE ALSO ANTIQUE RADIO, DX LISTENING,
HAM RADIO, SCANNER SCENE)
Ace Communications Trident
CB/ScannerRadar Detector (Saxon)(SS)
Dec 80
Build A
Low-Cost Morse -Code Transmitter (Lisle)(C) Aug 45
49-MHz FM Transmitter (Becker)(C)
Nov 39
Cobra Model 39 Plus S,O.S Portable
CB Radio (O'Brian and Scaduto)(G)
Jan47
Guglielmo Marconi (Rybak)
Apr 43
Making the Connection (Carr)
Dec 45
Philips DC777 AM /FM /Shortwave Stereo
Cassette Receiver (O'Brian and Scaduto)(G) Jun 14
Radio Polonia is Gone;
Polish Radio is Back (Jensen)(OX)
Aug 77
Radio Propagation,
Some Thoughts on Carr)(HR)
Apr 76
Radio Shack
Amplified VHF:UHF.'FM Portable
Antenna ( Saxon)(SS)
Jun 76
Archer Wireless AV Distribution
System (O'Brian and Scaduto)(G)
Jan 45
Deskmate Automatic House
Software (O'Brian and Scaduto)(G)
May 16
Duotone Outgoing Call
Restrictor (O'Brian and Scaduto)(G)
Mar 13
Plug'n'Power Computer
Interface (O'Brian and Scaduto)(G)
May 16
Pocketvision-26
LCD Color TV (O'Brian and Scaduto)(G)
Apr8
Realiolic
PRO-41 Scanner ( Saxon)(SS)
Feb 78,Aug 82
PRO -58 Scanner (Saxon (SS))
Jul 79
PRO-59 Scanner ( Saxon)(SS)
May 80
Ramsey FX -146 Two-Meter FM Transceiver
Kit (Kanter)
Dec 39
Readers' Requests (Yacono)(TT)
Jul 73
Real REC, A (Blechman)(FS)
Jan 83
Reassembling the Sky Buddy (Etis)(AR)
Dec 84
Receiver Front -End. A One -Chip (Carr)
Jun 53
Receiving Loop Antennas ( Carr)(HR)
Jun 74
Regenerative Capacitor-Discharge
Driver ( Rakes)(CC)
Nov 72
Regulator Applications ( Rakes)(CC)
Mar 70
Remote
-Control Analyzer,
A Simple (Yacono and Spiwak)(C)
Jun 38
Control, Sole Control
Universal (O'Brian and Scaduto)(G)
May 12
Controls, Convenience Light for ( Spiwak)(C) Aug 37
Key Car- Control System
Race (O'Brian and Scaduto)(G)
Jun 10
Resettable Shutdown Circuit ( Rakes)(CC)
May 73
Resistor Calculations Made Easier (Axelson)
Jun 58
(
n
Indicator (Yacono)(TT)
Launcher, Electromagnetic (Vollono)(C)
Rolodex Personal Planner
Model EO -100 (O'Brian and Scaduto)(G)
Aug 75
Oct 42
Oct 20
May 12
Solid -State
Aug 15
Jul
10
May 27,(LET) Oct 3
Sanyo
MCD -Z85 Portable Audio
System (O'Brian and Scaduto)(G)
Dec 12
Pulse Meter HRM-5520
Heart-Rate Monitor (O'Brian and Scaduto)(G) Jan 48
SCANNER SCENE (Saxon)(D) Jan 89,Feb 78,Mar 82
Apr 78,May 80,Jun 76
Jul 79,Aug 82,Sep 80
Oct 80,Nov 82,Dec 80
A Look at the Mailbag
Feb 78
Drive- Through Sermons
Getting to the Bottom of the Mailbag
Give Your Handheld A Boost!
Handheld That Won't Break the Bank, A
Monitoring
Motion- Picture Sets
Remote News Crews
New Kid on the Block
Nov 82
80
Aug 82
Mar 82
Dec 80
Jan 89
Scanning
Quick & Dirty Quad, A (Deupree)(C)
CB :Scanner Radar Detector
Cobra Trapshooter Solar
Remote Control (O'Brian and Scaduto)(G)
S
Apr 78
Oct 80
A Soviet Space Station
the Friendly Skies
Tuning in the GMRS
Vacation Scanning
Sep 80
Jul 79
Schematic Circuit -Design Software, Protel (HOR) Feb 61,
Secret Life of a Computer Products
Reviewer. The (Holtzman)(CB)
Jun 65
Self- Triggering Timed -On Generator ( Rakes)(CC) Dec 68
Series/Parallel Loop Alarm (Rakes)(CC)
Jan 78
Sharp Bookshelf Stereo System,CD Changer
Model CD -C900 (O'Brian and Scaduto)(G)
Apr 16
Sherwood SS -1500 Compact Stereo
System (O'Brian and Scaduto)(G)
Mar 6
Shinwe Communications
SR -001 Scanner (Saxon)(SS)
Jan 89
Shocking Facts About Surge Suppressors,
The (Angus)
Feb 35
Shortwave Revival, The (Jensen)(DX)
Nov 80
Shutdown Circuit ( Rakes)(CC)
May 73
Signal Detectors (Yacono)(TT)
May 70
Signetics NE602 One -Chip Receiver (Carr)
Jun 53
Silent Alarm (Rakes)(CC)
Jan 78
Simple Remote -Control Analyzer,
A (Yacono and Spiwak)(C)
Jun 38
Simulator Software (Blechman)(FS)
Jan 83
Sinewave -to- Squarewave Converter Rakes)(CC) Jul 70
Single -Plate Touch Sensor ( Rakes)(CC)
Aug 72
Sizing Up Your PC Needs (Holtzman)(CB)
Jul 68
Sky Buddy Saga, The (Ellis)(AR)
May 66
SOFTWARE
AutoMap (O'Brian and Scaduto)(G)
Nov 5
Britannica Software Compton's Concise
Encyclopedia (O'Brian and Scaduto)(G)
Feb 13
Buying Your First (or Next) PC (Holtzman)(CB) Aug 71
Delorome Mapping
Street Atlas USA (O'Brian and Scaduto)(G) Nov 5
Fathom Pictures ABC Sports Golf:
Palm Springs Open (O'Brian and Scaduto)(G) Feb 11
Gefen Systems CD Sound Music Manager
Software (O'Brian and Scaduto)(G)
Dec 5
Grolier Electronic Encyclopedia,
The New (O'Brian and Scaduto)(G)
Feb 9,Feb 18
Integrated Software Tools (Holtzman)(CB)
Oct 67
Mental Automation SuperCAD
Electronics Design Software (HOR)
Mar 65
Microsoft
Bookshelf (O'Brian and Scaduto)(G)
Feb 18
CD -ROM Multimedia Beethoven: The Ninth
Symphony (O'Brian and Scaduto)(G)
Feb 20
Word for Windows 2.0 (Holtzman)(CB)
Dec 86
Word Wizardry (Holtzman)(CB)
Apr 72
WordBASIC II (Holtzman)(CB)
Dec 66
(
Norton
Desktop for Windows (Holtzman)(CB)
Utilises 6.0 (Holtzman)(CB)
PC Globe Electronic Atlas
Feb 72
Jan 81
Nov 72
Driver (Rakes)(CC)
Light Sources (Carr)
Jun
31
Some
More Spectrum Analyzer Stuff ( Carr)(HR)
New Products and Some Questions
Answered (Carr)(HR)
Thoughts on Radio Propagation (Carr)(HR)
Sonic Kaleidoscope, Build A (Ray)(C)
Oct 78
Aug 79
Apr 76
Oct 58
Sony
CCD -F501 Video
Camcorder (O'Brian and Scaduto)(G)
Jan 50
CCD -FX510 8mm
Camcorder (O'Brian and Scaduto)(G)
Oct 17
Data Discman Model
DD1 -EX (O'Brian and Scaduto)(G)
Feb 13
EV-S3000 Hie VCR (O'Brian and Scaduto)(G) Dec 7
Pyxis GPS Receiver (O'Brian and Scaduto)(G) Jut 5
Sound Master II PC Sound Board
Covox (O'Brian and Scaduto)(G)
Jan 49
Soviet Space Station, Scanning A ( Saxon)(SS) Apr 78
Speaker Protector, Build A (Flynn)(C)
Mar 41
Spectrum Analyzer
Digital Sawtooth Generator, The ( Carr)(HR)
May 76
Poor Man's (Carr)(HR)
Oct 78
Spectrum Analyzer Stuff,
Some More (Carr)(HR)
Oct 78
Squarewave Oscillator ( Rakes)(CC)
Jul 70
Stac Electronics' Stacker (Holtzman)(CB)
Jun 65
Stepper -Motor Controller, PC -Based (Antonuk)(C) Jun 41
Stereo Cassette Deck,
Technics RS -BX606 (Feldman)(PTR)
Sep 27
Street Atlas USA
DeLorome Mapping (O'Brian and Scaduto)(G) Nov 5
Subwoofer, Build A (Whitehead)(C)
Jan 31
Sump Alarm (Yacono)(TT)
Sep 73
Super Bandpass Fitter (Rakes)(CC)
Jun 67
Super- Simple NiCd-Battery
Rejuvenator (Btechman)(C)
Sep 63
SuperCAD Electronics Design Software (NOR) Mar 65
Surge Suppressor
Protect Your Equipment With
The Power Block ( Yacono)(C)
Feb 37
The Shocking Facts About (Angus) Feb 35,(LET)Jul 3
Surround-Sound Processor
:Amplifier, Carver DPL -33 ( Feldman)(PTR)
Audio Source SS
Three /If (O'Brian and Scaduto)(G)
Jul 27
Oct 18
T
Tachometer Circuits, Fun With Analog (Carr)
Jul 59
Talking Compass (Mitschke)(C)
Dec 42
Tandy 2500SX /20 Multimedia
Feb 20
PC (O'Brian and Scaduto)(G)
Technics RS -8X606 Stereo Cassette
Sep 27
Deck ( Feldman)(PTR)
TELEPHONE (SEE ALSO PHONE)
AT &T Answering System
Telephone 1532 (O'Brian and Scaduto)(G) Aug 13
Amplifier (Yacono)(TT)
Feb 68
Build
A Cordless- Telephone Lock (Sokolowski)(C)
A Voice-Mail Alert (O'Kelley)(C)
An Emergency Telephone Dialer (Caristi)(C)
Circuit Parade (Yacono)(TT)
Duotone Outgoing Call Restrictor
Radio Shack (O'Brian and Scaduto)(G)
Intercom (Yacono)(TT)
Phone Guard Telephone Security Device
DTI (O'Brian and Scaduto)(G)
Jul 44
Nov 53
Sep 39
Aug 75
Mar 13
Aug 75
Jul
8
Aug 75
Recording Control (Yacono)(TT)
Apr 38
Ring Converter, The (Poeth)(C)
SR2 Selective Ring Processor
Multi-Link (O'Brian and Scaduto)(G)
Aug 15
Systems, Installing and Maintaining (Young) Nov 55
May 73
Tale-Timer (Rakes)(CC)
Tropez 900 DX Digital 900 -MHz Cordless
Telephone (O'Brian and Scaduto)(G)
Jul 8
TELEVISION (SEE ALSO VIDEO)
Citizen T530 Color LCD Pocket TV
with AM +'FM Radio (O'Brian and Scaduto)(G) Jul 16
Funai 9-inch TVrVideo
Nov 27
Cassette Player Feldman)(PTR)
Instant Replay Image Translator Standards Converting
VCR (0 Brian and Scaduto)(G)
Nov 12
Radio Shack Pocketvision-26
Apr 8
LCD Color TV (O'Brian and Scaduto)(G)
Sony EV -S3000 Hi8 VCR
(Brian and Scaduto)(G)
Dec 7
TV Answer: What's the Question? (Angus)
Sep 64
Zenith -Bose Color TV
Model 282794BG (O'Brian and Scaduto)(G) May 10
TESLA COILS
Fun With ( Rakes)(CC)
Oct 69
Make Your Own High- Voltage
May 31
Capacitors (Charlton)(C)
Test-Bench Helpers, Experimenter's Rakes)(CC) May 73
TEST EQUIPMENT
Feb 53
3 r 3 Visual Continuity Tester (Hampton)(C)
LU
z
GC)
(
PC
Mapps (O'Brian and Scaduto)(G)
PC -SIG Library (O'Brian and Scaduto)(G)
Nov 5
Feb 18
Philips ECG Cross - Reference Software (HOR) Dec 62
PIMA Cool Oldies Jukebox
Feb 11
(O'Brian and Scaduto)(G)
Protes Schematic Circuit -Design Software (HOR) Feb 61
Psygnosis Lemmings (O'Brian and Scaduto)(G) Feb 9
Radio Shack Deskmate Automatic
House Software (O'Brian and Scaduto)(G) May 16
Secret Life of a Computer Products Reviewer,
The (Holtzman)(CB)
Jun 65
Tuning Up (Holtzman)(CB)
May 68
Softworx PC Interlink File and Printer Sharing
Aug 21
System (O'Brian and Scaduto)(G)
Solder Spool (Yacono)(TT)
May 70
Soldering -Iron Controller (Yacono and Spiwak)(C) May 53
www.americanradiohistory.com
(
57
Function-Generator Kit (HOR)
Tuning
in the GMRS Saxon)(SS)
Theremin
Understanding Police Communications:
Jan 61
Cop Talk (Quarantiello)
Dec 76
United Nations Radio (Jensen)(DX)
Universal Electronics One For All 4 Home Control
Nov 20
Remote Control (O'Brian and Scaduto)(G)
Universal RS -232 Connector, Build The
Oct 62
(Tarchlnskì)(C)
kg
Coming: A New Restoration Project (EIIia)(AR) Apr
Jan
Theremin Plays Again, The (Ellìs)(AR)
Jan 22,Feb 68,Mar
THINK TANK (Yacono)(D)
Apr 70,May 70,Jun
558 Finale
558 Timer, The
Automotive Projects
Do You Compute?
Fun With Op -Amps
Microclips and More
65
76
73
70
73
75,Sep
73,Aug
Jul
Oct 72,Nov 75,Dec 72
Nov 75
Jan 22
May 70
Oct 72
558 and Alarm Circuits
Automotive Circuits
Fun With Op -Amps
FFeb
Tips
Readers Requests
Telephone Circuit Parade
Tiny Tuner, Build The (Salas)(C)
Tips and Tidbits (Ellis)(AR)
Tools tor Eimers and Elmees (Carr)(HR)
Touch Switch Circuit (Rakes)(CC)
Transistor Checker (Rakes)(CC)
Transmitter, FM (Becker)(C)
Jun
Jul
Aug
Jun
Nov
Sep
Jul
May
Nov
68
70
73
75
45
65
78
70
73
39
Travelpilot Vehicle Navigation System
Jun 7
Blaupunkt (O'Brian and Scaduto)(G)
Apr 70
Tri-Color Indicator (Yacono)(TT)
Jun 70
Trimmer Tool (Yacono)(TT)
Tropez 900 DX Digital 900 -MHz
Jul 8
arid
Scaduto)(G)
Telephone
(O'Brien
Cordless
Troubleshooting Parallel Connections (Yacono) Feb 41
TSM
8 -Digit Alarm Clock/Chronometer Kit (HOR)
/'m
Jul 26
Sep 80
May 68
Up ( Hottzman)(CBPianos
and Other Instruments
Electronically (Brown)(C)
Feb 29
Two
-Meter FM Transceiver Kit,
Ramsey FX -t46 (Kanter)
-Way AC Switch (Rakes)(CC)
TV Answer: What's the Question? (Angus)
TV/Video Cassette Player,
Funai 9 -Inch (Feldman)(PTR)
Dec 39
Sep 70
Sap54
Nov 27
U
Sep 73
Mar 73
Dec 72
More
58
Nov 22
Oct 22
Beckman DM10XL Multimeter (HOR)
Build A
(Recklies)(C)
Tester
Cable
Nov 4466
One -Amp Current Injector (Jahnson)(C)
Portable 2 -MHz
Jul 53
Frequency Counter (Caristi)(C)
Buyer's Guide to Low-Cost
Jul 35
(Spiwak)
Oscilloscopes
May 76
Digital Sawtooth Generator, The (Carr)(HR)
Apr
28
Multimeters
Digital
(NOR)
Fluke Series -10
Heathkit 1M -2410 Digital Frequency
May
22
(HOR)
Counter
Simple Remote-Control Analyzer,
Jun 38
A (Yacono and Spiwak)(C)
Nov 22
TSM Function- Generator Kit (HOR)
Some More Spectrum Analyzer Stuff ( Carr)(HR) Oct 78
(Harnpton)(C)
Feb 53
x
Visual
Continuity
Tester, 3 3
Sony MDP-605 CO!COViLP
Player (Feldman)(PTR)
TV Answer: What's the Question? (Angus)
VidiPax International Video Conversion
Service (O'Brian and Scaduto)(G)
Boing Box Sound- Effects
Mixer (O'Brian and Scaduto)(G)
Video Ttlemaker (O'Brian and
Scaduto)(G)
Videotapes, Bad (Feldman)
VidiPax International Video Conversion
Service (O'Brian and Scaduto)(G)
Visible-Light
Receiver (Rakes)(CC)
Transmitter (Rakes)(CC)
Visual Continuity Tester, 3 x 3 (Hampton)(C)
Voice
Disguiser (Vollono)(C)
-Mail Alert, Build A (O'Kelley)(C)
Voltage
Adaptor For Your Car, Build A (Yacono)(C)
-Level Indicator (Rakes)(CC)
Probe (Rakes)(CC)
Mar 8
Sep 12
Nov 31
Nov 13
Mar 70
Mar 70
Feb 53
Dec 53
Nov 53
Jun 47
Sep 70
Sep 70
w
VCR
Funai TVCP 9T 9-Inch TV/Video
Cassette Player (Feldman)(PTR(
Instant Replay's Image Translator Standards
Converting VCR
Memorex Model 87 (Feldman)(PTR)
Sony 2EV -S3000 Hi88 VCR
Vacation Scanning (Saxon)(SS)
Nov 27
Nov 12
Apr 26
Dec 7
Jul 79
Variable
-Frequency Oscillator (Rakes)(CC)
Oct 89
May 73
Sep 70
Voltage Divider (Rakes)(CC)
VIDEO (SEE ALSO CAMCORDER, TELEVISION, VCR)
Build an Automatic Power Switch
Nov 43
For Your TV (Vaughn)(C)
Jun 22
Colorburst SV1000 Video Digitizer (HOR)
Daewoo DVP-1060N Video
Jun 26
Cassette Player (Feldman)(PTR)
Mar 2
HDTV Update (Laron)(ED)
Onkyo SV70 Pro Audio/ideo
Jan 73
Receiver (Feldman)(PTR)
Panasonic PT-10L Compact
Apr' 5
Video Projector (O'Brian and Scaduto)(G)
Radio Shack Archer Wireless AN
45
Jan
Distribution System (O'ßrian and Scaduto)(G)
Sansui Model AV-7000 NV
Trip-Point Shutdown Circuit (Rakes)(CC)
looking for an 'illogic probe' for
"I have a logic probe
things that don't make sense"
Nov 13
Vtdeonica
V
Amplifier (Feldman)(PTR)
Oct 27
Sep 64
Feb 76
What's A Balun Transformer? ( Carr)(HR(
Whistler Interstate Tripmate Highway Travel
Apr 10
Planner (O'Brian and Scaduto)(G)
Jan 87
Why Not Try A Folded Dipole? ( Carr)(HR)
Winter Consumer Electronics Show,
May 5
The (O'Brian and Scaduto)(G)
Was Beams: Gain On
May 45,(LET) Oct 3
The Cheap (Carr)
With The Collectors Contest Results (Ellis)(AR) Feb 63
Word
Nov 68
BASIC ( Hottzman)(CB)
Apr 72
for Wndows, Microsoft ( Hottzman)(CB)
for Windows 2.0, Microsoft
Oct 87,Nov 68,Dec 66
( Hottzman)(CB)
Apr 72
Word Wizardry (Hottzman)(CB)
WWV and WWVH Offer More
May 78
Than You Think! (Jensen)(DX)
Z
Zenith -Bose Color TV
Model ZB2794BG (O'Brian and Scaduto)(G) May 10
May 27
"To be honest, it started out to be a pocket calculator-but it sort
www.americanradiohistory.com
of got out of hand"
ALL ABOUT
MICRO
PROCESSORS
We
The most common complaint
hear from old -world hams and
I
technicians about microis that there is no convenient way to visualize how they work.
They make that assumption because
most books treat microprocessors as
black boxes. They ask the user to
processors
explore what makes these
powerful chips tick in
an informative
but intuitive
style.
memorize what a given microprocessor does rather than try to explain how the microprocessor works.
Few introductory books, if any, give
the user a way to visualize and understand how a microprocessor works.
The lack of information is due in part
to the fact that microprocessors are
internally complex devices that require the user to juggle many facts
about their hardware and software.
However, although they are "messy"
to use in practice, they are built out of
simple logic devices and can be easily explained in a block- diagram fash-
BY TIMOTHY D. GREEN
dress containing the number to be
added. The microprocessor will execute the addition just after that and
place the result into memory.
At this point, you might be wondering: How does all of this occur? What
ion.
In this article, we will break -down
the microprocessor into simple logic
building blocks such as counters,
latches, and read -only- memories.
That will make it easier to show you
how and why a microprocessor works.
However, for the sake of brevity it will
be assumed that you more or less
know what those building blocks do.
A Microprocessor System. Figure
1 shows a small microprocessor system. The microprocessor can get its
program instructions from the Read Only Memory (ROM). It can get data
from or place data in the Random Access Memory (RAM), and it might
get or send data through the ports.
The control- lines, "read," "write," "input/output," and "memory" go to the
ROM, RAM, and input/output ports as
shown.
The microprocessor directs the
ROM, RAM, and the ports with its control and address lines according to
the microprocessor's internal controls
and according to the instructions it
receives. The ROM, RAM, and ports
are enslaved through the control and address -line signals that come
from the microprocessor. Each of
these devices are given unique address codes. As far as the microprocessor is concerned, the sole
function of each device Is to send
data to or accept data from the microprocessor on the data -bus lines
when it is selected by the microprocessor.
For example, assume that the microprocessor is about to execute an
"add to memory' instruction. This instruction consists of the "ADD" instruction code and two halves of a 16-bit
address in RAM. The microprocessor
will get the instruction code by setting
the address lines to the address of the
"ADD" instruction in ROM and activating the "read" and "memory" control lines. This will select the ROM and allow the instruction code to fill the data
bus so that the microprocessor can
read the ADD instruction. Then the microprocessor will set-up and read
from the next sequential address and
read the ROM two more times to get
the two halves of the 16 -bit RAM ad-
www.americanradiohistory.com
drives the microprocessorto do those
things? How are the address and control lines activated? How are these
things done in sequence? What
causes the microprocessor to get its
own instructions from the ROM? How
are these instructions interpreted and
translated into action?
To help explain, look at the internal view of a typical microprocessor
shown in Fig. 2. It shows several registers, which the microprocessor uses to
keep track of data and address information, the arithmetic -logic -unit (or
ALU), which performs math and logic
operations, and the internal data bus,
which allows the transfer of information within the microprocessor. It also
shows an instruction register tied to a
"control- unit," which is the source of
several control -lines. Although the
control -lines shown only point in the
direction of the external devices they
control, every part of the microprocessor is connected to and manipulated by the control -unit.
The control -unit runs the microprocessor, sequences and commands its internal parts, and interprets
and executes the instructions in full.
Completely understanding exactly
how the control -unit works is the key to
59
CHIP
SELECT
ADDRESS
DECODE
LOGIC
ADDRESS
BUS (16
CLOCK
OSC.
SELECT
READ
CLOCK
WRITE
MEMORY
MICROPROCESSOR
POWER
RESET
INPUT/
OUTPUT
RESET
OUTPUTS
INPUTS
Fig. 1. In a microprocessor system, the microprocessor treats all the other system
components as devices to give data to and receive data from.
understanding how and why a microprocessor works.
gD
A Controller. The controller circuit
shown in Fig. 3 is not a true control unit,
but it has the feel of one and contains
most of the essentials of a control unit.
Ignoring the dashed portion of the
circuit and the instruction latch for
now, a binary counter counts clock
pulses and sends its count to the address lines of a programmable ROM
(PROM). The PROM looks at the address and sends the value of the data
located in the address to the input of
the octal latch that's connected to the
control lines. That latch captures and
holds this data at its outputs, thus manipulating the control lines.
Notice that the binary counter
clocks on the falling -edges of the
clock, while the latch clocks on the
rising- edges. That is done for making
clean, stable transitions in the latch output data and for synchronization.
The latch- output lines can be used
as a set to represent a number or value. They can also be used individually
as controlling signals to other logic
devices. For example, when used individually, these lines can drive other
gates, flip -flops, counters, latches,
PROM's, RAM's, and other devices.
As the counter counts, it provides
new addresses to the PROM, which
sends out the pre -programmed data
from each requested address. One of
these lines is fed back to the "clear"
input of the counter as shown in Fig. 3.
That allows a fixed -length process to
run in a continuous loop provided the
data and instructions needed for the
process are stored in the PROM.
More PROM's can be added to provide more control lines, as indicated
by the parts with the dashed outlines.
The outputs of the counter would feed
the same corresponding address
lines of each new PROM.
Some Examples. Figure 4 shows a
controller without an instruction latch
running a data -acquisition system.
The user of this system would program
the PROM to select an analog channel to be sent through the analog
multiplexer, start and read the analog-to-digital- converter, and latch the
www.americanradiohistory.com
output data. This sequence of instructions or steps would then be repeated
over and over again as part of an
instruction loop. That can be done for
a schedule of 100 channels, 200
channels, or any number of channels.
Figure 5 shows another such simple
controller running a beacon transmitter and sending Morse code. A fixed length, repealing message in Morse
code would be programmed into the
PROM with the sequence to turn on
the transmitter and the keyer.
Both of the circuits in Figs. 4 and 5
could have been controlled by the
microprocessor system back in Fig. 1.
The ROM in the microprocessor system would just have to contain a sequence of instructions to manipulate
the output-port lines, which would in
turn control the external devices. Both
the simple controller and the microprocessor system solve similar control
problems and allow the user to program simple, arbitrary -length control
sequences with great flexibility. However, the microprocessor can do
mathematical and logic operations
on its data as well.
The reason that a simple controller
lacking an instruction latch cannot
serve as the control -unit in a microprocessor is that it would only be capable of running one sequence of
instructions located in the PROM. A microprocessor's control -unit must be
able to run many different control sequences, therefore it must be able to
accept input from the outside world
to select the desired control sequence from those in the PROM. That
input is received by the control -unit's
instruction latch.
The Instruction Latch. To help point
out the importance of the instruction
latch look back at Fig. 3. Note that the
binary- counter outputs only set the
lowest six address lines of the PROM.
That allows the counter to count out
up to 64 sequence steps at a time
rather than stepping through the
whole PROM.
The instruction latch supplies the
PROM with eight, additional, higher address lines. The input latch and the
counter, together, are used to index
256 separate sequences of up to 64
steps each. In a microprocessor, each
of the 256 possible latch codes are
used as instruction or operation
codes. Each instruction code is a sin-
ACCUMULATOR
ALU
FUNCTION SELECT LINES
(TO CONTROL UNIT)
PROGRAM
COUNTER (LOW)
TEMPORARY
INPUT #1
v
PROGRAM
COUNTER (HIGH)
INPUT #2
ARITHMETIC /LOGIC UNIT
(ALU)
DATA COUNTER
DATA
(LOW)
DATA OUTPUT
STATUS OUTPUT
r
EXTERNAL STATUS
INTERNAL STATUS
CONTROL -UNIT
DATA OUTPUT
PROM
LATCH
PROM
LATCH
PROM
LATCH
PROM
LATCH
INSTRUCTION
REGISTER
INTERNAL DATA BUS (8)
DATA BUFFER
COUNTER
(HIGH)
ADDRESS LATCH
ADDRESS LATCH
(LOW)
(HIGH)
COUNTER
J
(8)
EXTERNAL
DATA BUS
L
(8)
ADDRESS BUS
ADDRESS BUS
-LOW
-HIGH
HALF
HALF
(SEE TEXT)
f
CLOCK
RESET
READ
WRITE
MEMORY
INPUT
/OUTPUT
Fig. 2. The inside of a microprocessor is much like the system the microprocessor sits
in; there's a data bus for communication between the components.
gle code that indexes a whole sequence of sub -operations within the
microprocessor. A sub -operation may
be used to manipulate the controls of
a latch, a counter, or the ALU. Each
sequence of sub -operations will perform one complete microprocessor
operation (such as ADD).
As mentioned earlier, more PROM's
may be added to the control -unit, so
that the new PROM's share the same
address bus as the first PROM. It is not
uncon-Imon for a microprocessor's
control -unit to have more than 80
control lines (or, more than ten
PROM's).
Two of the control lines from the output latches of the PROM's go to the
"clear-counter" input of the counter
and to the "latch" control of the instruction latch. The PROM must be
programmed to activate those two
lines at the same time to get a new
instruction at the end of a sequence,
which might be smaller than 64 steps
long.
The control -unit shown in Fig. 3 must
be modified in two ways to enable it
to handle some special instructions
and features. These will be discussed
later, as they are needed.
Microprocessors vs. Controlers.
The operation of a microprocessor
is
directly parallel to the operation of
the simple controller. However, since
the microprocessor itself contains a
control unit, the microprocessor operates at a "higher level" than a controller. In this higher level, the microprocessor controls the external system
in "indirect" instruction steps, at a
www.americanradiohistory.com
lower speed than a simple controller.
However, a microprocessor can perform many different operations as is,
while a controler would require a
PROM for each sequence that it must
perform.
Back in Fig. 4 for example, we
showed how a simple controller
would operate a data- acquisition system "directly" from a PROM. There is a
one -to -one correspondence between a PROM's latched data and the
operation it performs. However, if the
data -acquisition system were controlled by the microprocessor system
of Fig. 1, the microprocessor system
would manipulate the output -port
lines to control the same devices
using a series of "indirect" instructions
from the ROM. There would be no
one -to -one correspondence be-
61
ALWAYS ON
_ ..P
FROM LATCH
(8)
FROM COUNTER
(6)
{{''
\
- 1,'
- f\
t_
r
I ONABLT
1
ADDITIONAL
)I
PROM
I
16K
(27128)
1
I
i
i
I
1
I
I
CHIP
LSELECT
G
READ J
do
DATA
Lp\
LINES
I
))
IV
- - -J
(-
ENABLE
CONTROL LINES
OCTAL
LATCH
(74374)
(8)
(8)
I- - - - - -
I
t
L
J'
TO DEVICES
LATCH_
r- - -I
U
ó
ALWAYS ON
ALWAYS
OUTPUT
ENABLE
ON
OCTAL
8 BIT
INSTRUCTION
CODE
LATCH
INSTRUC
-TION
LATCH
TO 8 HIGHER
ADDRESS
LINES
D7
D6
I
DATA
I
D5i
D4
PROM
16K
(27128)
CLEAR
BINARY
TO 6 LOWER
COUNTER
ADDRESS
LINES
D3
D2
I
D1
i
DO
I
CHIP
READ
SELECT
CLOCK
b
program- counter and the data counter, is an octal latch. Each register, or latch, has two control lines to be
connected to the control- unit's output
latches: one to "latch" or capture the
data at the inputs and the other to
"three- state" its outputs. The "three state" control is also called the "output
b
ALWAYS ON
COUNT
LATCH
J
FROM
CLOCK/OSC.
LATCH
TO CLEAR
TO LATCH
OUTPUT
OCTAL
LATCH
enable."
The arithmetic/logic unit (ALU) performs such operations as addition,
(74374)
ALWAYS ON
CONTROL LINES
TO DEVICES
Fig. 3. The control unit is the key to how a microprocessor processes data and
performs operations. There are simple descrete controllers available that lack the
instruction latch shown here.
tween the instruction codes in the
ROM of Fig. 1 and the controlling signals on the output -port lines.
Furthermore, the simple controllers
suitable for Figs. 4 and 5 will run their
2?
m
13
á
á
62
A Simple Microprocessor. Looking
back at Fig. 2 as a guide, let's discuss
the intended functions of each of the
microprocessor sub -components. A
detailed explanation of these subcomponents is essential for programming the control -unit.
The microprocessor's internal,
eight -line data bus connects the outputs of each register to its own input
and to the inputs of the other registers
to allow data to be transferred to and
from the registers, the ALU, the data
buffer, and the address latches. Any
register, latch, or device that sends
data onto the internal data bus must
have three -state (low /high /high -impedance) logic outputs so that it can
"disconnect" itself from the bus when
it is not needed, as only one device
may place data on the bus at any
one time.
Each register in Fig. 2, including
both the low and high halves of the
lions since the instructions are decoded by the microprocessor's control -unit.
To summarize, although the micro-
control sequences exactly at the
its controlling "indirectly" and more slowly than the
clock speed. The slowest device that
these controllers control is the only
thing that limits their operating speed.
A microprocessor, on the other hand,
will run its control- instruction sequence at a lower speed than the
clock speed. That is because the miccroprocessor must run a few sub -operations at the clock speed for each
control operation it must perform.
Another key difference is that if the
ásimple controller had a lot of devices
to control, it would need several
PROM's. However, the microprocessor
needs only one PROM for its instruc-
simple controller, it uses a fixed set of
instructions which are easily coded
into a single PROM. In general, a microprocessor is a compromised controller. Instead of building a separate
and complete control -unit to perform
each complex task, a microprocessor
is used to perform each task with a
sequence of instructions selected
from a fixed set of instructions. The
complete freedom that comes with
using a control -unit is traded for the
restricted freedom of using a given
microprocessor's structure and instruction set.
processor does
www.americanradiohistory.com
subtraction, incrementing, decrementing, and logical operations on
the data present at its inputs. The selection of each operation and which
input or inputs to operate on is made
by giving a binary code to the ALU's
control lines. These control lines are, of
course, connected to the control -unit.
The ALU can accept data from the
temporary register and any other register except the instruction register. The
temporary register is used as a temporary holding place for ALU input
data.
The accumulator register is used
only for the programmer's data. The
control -unit must not disturb its contents unless an instruction tells it to do
so.
The ALU has outputs for data results
and the "status" of the results. The
data -output register is a temporary
holding place for the results of the
operations. The ALU's status information indicates whether or not there
was a bit carried during addition,
(Continued on page 93)
ALU's
Nearly everyone knows that the
ability to send messages from
one place to another in the
form of an electrical code has been
around for about 150 years. But relatively few realize that the instruments,
and even the code itself, have undergone many changes in that time. In
this article I'd like to take a look at
some of the devices that opened the
age of electrical communication,
and then trace the development of
the Morse code and code -sending
devices to the present time.
The First Telegraph. Samuel Morse
didn't use either a key or a letter code
for his first telegraph. Instead he used
a "portrule," a number code and a
"register," The portrule was a wooden
stick with a groove designed to hold
small lead blocks. (Similar devices
were used in printing.) Each of the
lead blocks had protrusions arranged
to represent the numbers zero
through nine. In use, the portrule was
pulled past an electrical contact and
the protrusions closed the circuit in a
sequence corresponding to the
number.
At the receiving end, a strip of paper was automatically inscribed by
the register with marks corresponding
to the protrusions and numbers. An
operator would then look up the numbers in a code book and write down
the appropriate letter, word, or
phrase. There are a few holdovers of
that system still in use-the familiar
"73" or "best regards" of ham operators and the "30" used to mark the
end of newspaper and wire-service
stories are Iwo examples of that.
The system worked-but slowly. Unlike others who were experimenting
with electrical telegraphs at the time,
Morse didn't stop inventing when he
had a system that barely functioned.
With the help of his assistant and partner, Alfred Vail, Morse improved his
telegraph until it was simple, reliable,
and convenient to use. The portrule
and number code were the first to go.
Enter the Telegraph Key. The first
telegraph key was a strip of brass fastened to a block of wood and a wire
at one end, and be t upwards at an
angle over a contact at the other.
Pushing down on a knob at the free
end of the strip closed the circuit.
The key used by Morse in his 1844
THE
CODE MAKERS
Trace the history of code and code -sending gear from its
earliest days to today's computerized equipment.
BY LARRY LISLE, IK9KZT
demonstration between Washington
and Baltimore was more elaborate,
with a pivoting wooden lever and
screw adjustments. Conven-ional or
"straight" keys have changed very little since then.
Morse and Vail also dropped the
number and code -book idea. After
several false starts, they came up with
the system of dots and dashes for letters, numbers, and punctuation that
became known as the American
Morse Code. In 1851 the code was
modified in Europe and called the
Continental or International Morse
www.americanradiohistory.com
Code. Thai is the version of the code
that was adopted for used when wireless (radio) telegraphy was developed.
As operators became more experienced., it was found they could understand the sound of the register as
easily as they could the marks on the
moving strip of paper. That led to the
invention of the "sounder" by Vail in
he early 1850's. The sounder consisted of an electromagnet and a
lightweight, movable arm that clicked
when the current flowed and the circuúi was closed, and clicked again
63
wired for electricity, code -practice
machines were built to run with electric motors, and later ones had built -in
code oscillators. Incidentally, should
you pick up one of these old devices
from a flea market, etc., be very careful. Some were built to poor standards
of safety, and even in the better ones
the insulation may have detèriorated.
If the earphones, key, or cabinet is
connected directly to the power line,
you might receive a deadly shock.
Improved Sending Devices.
A Signal Electric key and sounder in a
homemade metal resonator.
An Instructograph AC-powered code practice machine. This model had a
built -in oscillator. The knobs were used
to control volume and speed.
A spring -powered Morse -code sending
machine. A perforated paper tape was
Sending high -speed messages for
hours at a time with a straight key
could be very tiring. Many operators
had their careers cut short by a condition called a "glass arm." That was
caused by the constant switching of
opposing sets of muscles in the fore-
Here's an assortment of semi -automatic keys or "bugs:" From left to right they are an
old and new Vibroplex, a McElroy, and a Johnson Speed-X.
pulled past the electrical contact and
operated a sounder hooked to the
binding posts. The speed control is
located at the opposite corner.
when the current was turned off. A
short interval between the clicks was a
dot; a long interval was a dash.
Trying to copy a sounder in a noisy
office could be difficult, especially if
there were several other sounders going at the same time. The usual practice was to mount the sounder in a
wooden or sheet -metal box, open on
one side, which was called a resonator. That made the clicking seem
louder and gave each sounder a distinctive tone.
Learning the code in the wire -telegraph days usually meant hanging
around the telegraph office and
64
doing odd jobs. During the slack periods, the operator might then be persuaded to teach the code on a
practice set. Another way, if you could
afford it, was to rent a code -sending
machline. These devices used a pa-
An assortment of electronic keyers: From left to right they are A Mon -Key (the first
electronic keyer), the "TO" by Hallicrafters, and models made by Hammarlund and
Heath. A "Vibro- keyer" bug sits on top of the Hammarlund unit.
per tape punched with holes to represent the dots and dashes of the
code. A spring -wound motor pulled
the tape past a contact, which operated a sounder. When wireless came
in, a buzzer was substituted for the
sounder. These machines could be
adjusted for whatever speed you
wanted -something not always possible when a live operator was doing
the sending!
As more and more homes were
www.americanradiohistory.com
arm from full on to full off and back
again.
The earliest remedy was the "double -speed key" also known as the
"double- action key" or more commonly, the "sideswiper." The side swiper key moves from side to side
instead of up and down. There are
contacts on either side and the operator holds the key against one of
them longer for dashes than for dots.
(Continued on page 89)
ANTIQUE RADIO
By Marc Ellis
ast month, we began
reassembling our Sky
Buddy model S -19R receiver, which had been
partly dismantled for cleaning and dial -cord
restringing. In this column,
we'll be completing the job
and testing the set for operation. For those who have
just joined us, the Sky Buddy
was Hallicraffers "low -end"
shortwave receiver during
the late 1930's. As such, it
was quite a popular starter
set for shortwave listeners
The Sky
Buddy: All
Together
Again!
the main tuning and band spread control drives were
restrung with new cord. And
that cord had better last
quite a long time! There's no
way to restring those controls without disconnecting
the subchassis (an arduous
job indeed) and removing
it from the main chassis.
The removal (not to mention the subsequent
reinstallation) was almost as
difficult as the disconnec-
Take the time to make
good clear notes when disconnecting wiring.
The speaker in the S -19R
has six leads: Iwo to the
field coil (which also serves
as the power -supply filter
choke), two to the primary
of the output transformer
(which is mounted on the
speaker frame), and two
from the voice -coil circuit to
the closed- circuit headphone jack (which mutes
tion. The subchassis is
the speaker when phones
virtually locked in place by
are plugged in).
the radio's. front panel,
In a hurry to get on with
the restoration work, had
which must have been inmade only a few rough
stalled after the subchassis
was. And the front panel is
sketches to indicate where
not now removable bethose leads were concause it was fastened to the nected. When reinstallation
time rolled around, found
main chassis by some type
that hadn't adequately
of a spot -welding process.
Taking out the subchassis
differentiated between a
with the front panel in
pair of terminal lugs where
place requires a bit of inge- a couple of the wires were
nuity and a bit of forcing, as to be connected. (I'd carefully marked one "top" and
described in last month's
column. And if anyone out
one "bottom," but now
there in reader -land has
wasn't sure whether "top"
figured a method for rereferred to the terminal that
stringing the Sky Buddy's dial would be uppermost with
the set in operating position
cords without going
through this exercise, I'd
or to the terminal that was
certainly like to hear about
uppermost with the chassis
it!
upside down for servicing.)
had also indicated the
wrong tube socket as the
THE LOUDSPEAKER
connection point for a third
HASSLE
lead. And just to add to the
With the tuning subassembly back in place,
complication, the color
the only major component
coding on the grimy and
time -faded wires no longer
still to be installed was the
loudspeaker. That took a
seemed as clear to me as it
little longer than necessary
did when removed them.
"Big deal," you may think,
because of uncertainties
"Ellis has a schematic of the
about the lead connections. And while can
set. What's so hard about
finding the connection
probably blame the Hallicrafters design engineers
points for six speaker
for the previously described
leads?" In actuality, howhassle, can blame only
ever, that was more of a
myself for the difficulty had problem than it seemed.
with the speaker. The moral: Set designers of the era
I
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I
-all
The front view of the Sky Buddy
try out.
together again and ready to
and newly -licensed hams.
This series of articles began in the May, 1992 issue,
with a discussion of the Sky
Buddy's history. Restoration
work started the following
month, and has been continuing at intervals ever
since.
THE DIAL CORD
HASSLE
Last month's column
chronicled the disassembly,
cleaning, reassembly, and
reinstallation of the sub chassis containing the main
tuning /bandspread capacitor and associated drive
pulleys. In the process, both
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www.americanradiohistory.com
I
65
were not as concerned
about keeping interconnecting leads short as they
were about cabling them
neatly together. So found
myself attempting to trace
circuit pathways from one
side of the chassis to the
other via wires obscurely
bundled up in harnesses.
The confusion created
for myself extended what
should have been a 10minute job into one that
lasted for more than an
hour. So don't make the
mistake did! Take the time
to sketch accurate diagrams showing the
locations of all the connections that you remove. In
the long run, that will save
you time and possibly even
prevent you from damaging irreplaceable parts by
wiring them incorrectly.
I
I
switch terminal that it didn't
look disconnected.
ran into a similar problem with an Echophone set
that restored on these
pages a few years ago and
know why, in all likelihood,
those wires were cut. During
World War II, in a security related move to restrict
shortwave listening, our
government apparently encouraged radio service
shops to disable certain
shortwave bands on sets
that were brought in for
repair.
I've heard of cases where
the zealous service man
crushed the shortwave
I
I
where definitely was not
receiving the full complement of local stations. The
tuning in that band also
seemed a little broad, and
signals were weak. A bad IF
stage maybe? Only further
testing will tell!
but perhaps someone will
now. If you have information
about this issue, how about
contacting me? l'lI be delighted to print your
recollections in this column.
I
I
FINAL ASSEMBLY
AND TEST
After cleaning and re-
READER COMMENTS
Now that the Sky Buddy
restoration has been run-
installing the knobs, tuning
dial, and dial pointer, all
had left to do before the
S -19R could be tried out
was to add a line cord. The
old one, dangerously
I
ning for a while, some
I
cracked and deteriorated,
had been removed early in
the restoration project.
wish could tell you that
I'd
able to dig up a
been
coils, damaging them
replaceperiod
perfect
repair.
hope
of
all
beyond
ment for the cord, but I'm
Luckily this radio (and the
not even sure what the
Echophone) were disabled
original looked like. The
in far gentler fashion, so
that all functions could easi- clumsy solder joints and
shreds of previous wiring at
the set's cord connections
indicated that the deteriorated cord had itself been
a replacement. So satisfied myself by installing a
length of modern black zip cord having an innocuous
molded plug.
When first turned the set
on, not a sound came forth.
My heart sank because the
set had played a bit when
tried it out prior to disassembly. figured that
must have messed up the
speaker wiring after all, perThe newly reassembled Sky Buddy as seen from the rear. The
to
get
was
a
bear
haps burning out the unit in
the
IF
cans)
tuning control subchassis (behind
the process. Then realized
back in!
that the problem could just
as well be dirty contacts on
ly be restored after the war.
ECHOES OF WWII
But doubt that either of the the phone jack's speakerhave to admit, though,
muting switch.
rumfolks
who cut those wires
to
that being forced
That hunch was correct,
would have imagined that
mage around tracing wires
since shorting out the
half a century would pass
did have its up -side! acciswitch with a clip lead imbefore the severed condentally discovered that
mediately brought the Sky
were
found
and
the
nections
from
wires
of
the
one
Buddy back to life. could
soldered back in place!
oscillator coil to the band hear activity on all bands
In one of the Echophone
switch had been neatly
and, since was hooked up
invited
readers
articles,
severed, effectively disabwho might know something to a good antenna, even
ling band 2 (1.7 -5.5 MHz). It
pulled in several foreign
about those wartime govwould have otherwise
shortwave stations.
ernment guidelines for
taken me quite a bit of time
Performance was lackto
sets
shortwave
disabling
to find that problem behowever, particularly
luster,
No
us.
write
and
enlighten
so
wire
was
cut
the
cause
one responded back then, on the broadcast bandcleanly and so close to the
I
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66
www.americanradiohistory.com
reader comments have
started to come In, and
have room for a couple of
the letters here. To start off,
was pleased to receive a
note from Alan Douglas, author of the very important
three -volume reference set,
Radio Manufacturers of the
1920's (published by Vestal
Press, Vestal, NY and available from most major
sources of antique -radio litI
erature).
In his
communication
(which was typed on a reproduction of Atwater Kent
Manufacturing Works stationary dating from the
early 1900's1), Alan pointed
out that the yellow deposit
had reported cleaning
from the S -19R's IF transformers and other metal parts
(October, 1992 issue) could
very well have been a
compound of cadmium.
Cadmium plating of steel
parts, he went on to point
out, began about 1930 and
has been common ever
I
since.
Cadmium plating normally has a bright metallic
look, but after long -term exposure to the atmosphere,
cadmium oxide (brown)
and /or cadmium sulfide
(yellow) deposits can form
on the surface. When
cleaning off such deposits
during restoration projects,
extreme caution should be
used because cadmium is
a poisonous substance and
inhaling its dust can be
quite dangerous.
Many thanks to Alan for
(Continued on page 91)
COMPUTER BITS
By Jeff Holtzman
I n past columns, have
I recommended buying as
I
much computing muscle as
you can possibly afford.
However, in a letter that
recently received, reader T.
G. chides me for being too
gung -ho with those recommendations. Perhaps he is
right. It is possible to get by
with less. But getting by is
I
The XT
Syndrome
not the issue. don't recommend purchasing powerful
computers for the sake of
ownership. I'm not advocatI
,ed
.
0.
4
`,
/%rOMY/.
;73,'1N
Ani
%\\N\I/
\iJi//
\te
\\\LII/
\\II/
\!'f
\"R,,
11111111111a=
.._.
Fig. I. In just a few years, all- digital global communications
networks and high - powered personal computers will totally dwarf
the already tremendous changes of the past 30 years in the fields
of communications, consumer electronics, computers, and
entertainment.
ing some high -tech form of
conspicuous consumption.
My reason is simple: It takes
a lot of power to deal with
what I'll call "rich data."
RICH DATA
Computer users who
have never used a Macintosh, an Amiga, a NeXT
station, a workstation running Motif or Open Look, or
a plain old PC running Windows may have trouble
imagining computer
screens displaying anything
but 80 x 25 screens of text.
Consequently, that type of
user has trouble imagining
why anyone would want to.
And because said user has
undoubtedly paid significant dues in mastering a
program or two (DOS WordPerfect or 1 -2-3, for
example), he or she resists
change in direct proportion
to the effort expended in
paying those dues -not to
mention the status earned
thereby.
There's a significant problem with that world view. It
assumes that computers
are here simply to improve
the efficiency of common
procedures -such as writing letters to the editor. Of
course they do that, but
they also open up a whole
new world of experience
that has no analog in past
experience. Think about
video games. Think about
the kind of show that you
get at a good planetarium.
scribe these rich new forms
of information.
A DIGITAL WORLD
We're already living in a
digital world; it's only going
to become more so. Technologies including High
Definition Television (HDTV)
and ISDN are going to
make a big difference during the next decade. You
may have heard of ISDN.
Officially, the acronym
stands for Integrated Services Digital Network, but
due to interminable delays,
wags have for years supplied alternate expansions:
e.g., It Still Does Nothing.
However, that is changing. Some analysts think that
ISDN will be available to
more than 50% of telephone subscribers by the
end of 1993-little more
than a year from now. We'll
you see in movies like Roger have to buy new phones,
Rabbit and Terminator 2.
and they'll be expensive at
Think about what composfirst. But we'll be able to
ers like Todd Rundgren and
throw away our modems,
Philip Glass are doing. Think install a cheap digital port
about fractal graphics.
(somewhat like an RS -232
Think about desktop pubcard), and get 27 times
lishing (which didn't exist ten better performance than a
years ago). Think about
2400 bps modem. We'll
desktop -video production
also get videophones,
(coming in a big way in the cheap. Talk to Grandma
next few years).
during the holidays, let her
Those phenomena have
see the kids.
one thing in common:
We're going to need
They're all built around rich
even greater bandwidth
data: gobs of formatted
than ISDN can provide to
text, high -resolution truepurchase and download
color graphics, animation,
videos on demand. Pilot
recorded and synthesized
sites on both coasts already
sound, and full -motion vidprovide that type of service.
eo. Like it or not, rich data is In the business environment,
here to stay. The "MTV genpresentations have evolved
eration" simply demands it. rapidly over the past few
Those demands are tear- years to include fancier
ing down the wall that's
and fancier graphical eledividing education and en- ments. That trend is likely to
tertainment. Some use the
continue by adding sound,
term "infotainment' to desimple animations (e.g.,
Think
about the effects that
www.americanradiohistory.com
67
Now you can
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LISTEN!
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Shatatke Ester
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It also profiles major world broadcasters. Includes hundreds of
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Forrest includes complete data for
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If you experiment with ICs,
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projected sales growth),
and video clips. Clearly,
that environment demands
powerful computers to accomplish anything beyond
mindless data entry.
Factories need to collect
data, predict and schedule
maintenance activities, and
alert management to inventory and manufacturing
problems. Workers need
on- demand video training.
A 30- second video (available instantaneously across
the network) detailing a
complex assembly procedure is infinitely more
effective than five pages of
dense prose and static diagrams. Imagine receiving
a VHS tape or interactive
CD -ROM instead of printed
assembly instructions when
buying your child's (or
You can get HighText books at
your favorite technical bookstore,
electronics parts dealer, or radio
equipment dealer. Or order direct
from HighText! Include $3 per
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tax. U.S. funds only please.
IiighText
I
I
I
I
7128
68
L
Miramar Road, Suite 15L
San Diego, CA 92121
out. Businesses like GM, IBM,
Digital, and countless others
are trimming the fat. Corn ponies large and small are
releasing those who never
showed enough initiative to
learn new things, to reinvent themselves, to improve
their worth to the company.
only wonder how they'll
get new jobs when their
skills are five, ten, and even
twenty years old.
I
Nonetheless, education
will follow, and soon. If the
public institutions don't get
with the program, expect
greater and greater numbers of private institutions to
take over. Washington is algrandchild's) next bike.
ready talking about
Schools have unique
education credits that can
needs that far exceed the
be applied to both public
capabilities of the Apple II's
and private schools.
and C64's that once promThe U.S. has supported a
ised salvation.
"secure," complacent way
of life for the past 60 or so
TEACHER'S PEST
years. However, that ostrich
Reader T. G. mentions
attitude has come back to
"many middle -aged school
haunt us. The old ways were
teachers... who only want
to write letters and perhaps good enough, so we didn't
modernize our steel plants,
look at CompuServe;' and
our semiconductor fabricathen goes on to imply that
tion, or our educational
they don't need big 486's
systems. Now we're paying
with lots of RAM and hard
the price. We didn't moddisk space. That's probably
ernize, so the Pacific Rim
true.
countries surged ahead.
It is also regrettable. It is
The solution is not to try to
regrettable both for the
regain dominance in parteachers themselves and
ticular industries. The world
for our society. have sevis much too complex for
eral school -age children,
that. But that's a topic for
and frankly don't want
them to have those kinds of another time. For now, don't
let anyone fool you. The
teachers. want my kids to
world is going digital. Everybe taught by war -scarred
veterans who've been tried thing will be available in
digital form. You need lots
by fire, who've lived to tell
of computer power to reabout it, and who are eager for more. want my kids trieve, create, and
manipulate rich data.
to experience, first -hand,
It's scary, and it's hard. But
that
the new possibilities
even the smallest successes
these technologies are
are satisfying. And a big
opening up. want my kids
success will let you leave
to experience the frustrayour
mark on the world.
the
of
using
Joys
tions and
I
A steal at $14.95.
these tools. It's good training, both professionally and
personally.
That "middle-aged
school teacher" type of
complacency is on the way
www.americanradiohistory.com
-
we
(1
ñ Year
(Friend
of
`Electronics
Fun this Clii ristm a
Ni
Does fighting the crowds at Christmas short circuit your holiday fun? Don't blow a fuse this
year. ..for the friend who shares your love of
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PLUS...Gizmo, our honest and straight- shooting review of the latest consumer -electronics
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including antique radio, shortwave listening,
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www.americanradiohistory.com
-1 yr/$21.95
CIRCUIT CIRCUS
By
Charles
D.
Rakes
his visit, we are featuring
Cl and potentiometer
several circuits built
R4 ties
around the unijunction transistor (or UJT as it
UJT Circuits
is
commonly called). The UJT
is a two- layer, three -terminal
PN device that has two
bases (B1 and B2) and a
single emitter (known as the
gate). If you're relatively
new to electronics or just
haven't crossed paths with
the UJT, then the following
circuits just may spark an
interest in using this device
some future circuit or
project.
in
RELAXATION
OSCILLATOR
Figure 1 shows a UJT configured as a relaxation
oscillator. In that circuit, the
positive supply voltage is
connected to B2, while the
negative side of the supply
is connected to B1. The
emitter terminal is connected to the junction
formed by timing capacitor
R4;
the emitter to the
positive-supply rail. When
the emitter voltage is below
the trigger level of the UJT,
the impedance between its
emitter and B1 is very high.
But when the emitter voltage rises to the trigger
level, the impedance between the emitter and B1
drops dramatically.
At the instant that power
is applied to the circuit, the
voltage across Cl is near
ground. As time passes, the
voltage across Cl rises.
When the charge on Cl
reaches the UJT's trigger
level, Ql turns on, discharging Cl's stored energy into
BI's negative -return resistor,
R3, producing a fast -rising
pulse at BI. At the same
instant, the resistance between B2 and ground is
lowered, causing a similar
but opposite (negative)
pulse at B2. After Cl has
discharged, the cycle starts
over.
The basic UJT circuit in
+9 -16V
Fig.
1
can supply output
signals for a number of applications. It may be used
as a clock generator, a
timer circuit, a sawtooth
generator, or a positive- or
negative -pulse generator.
MODIFIED RELAXATION
OSCILLATOR
Our second UJT circuit,
shown in Fig. 2, is a slightly
modified version of the
basic relaxation circuit
shown in Fig. 1. A small 8- or
16 -ohm speaker replaces
BI's ground return resistor
(R3), while a three -position
switch (S1) and three capacitors (C1 -C3) replace
+9 -16V
SPKR1
8 OR 1652
Fig. 2. In the modified
relaxation oscillator, an 8- or
16 -ohm speaker replaces R3,
while a three -position switch
(Si) and three capacitors
(C1 C3) replace CI.
Cl in Fig. 1. The switch/
capacitor combination
is
used to set the oscillator to
operate in one of the three
PARTS LIST FOR THE
RELAXATION OSCILLATOR
70
Fig. 1. In the relaxation
oscillator, B2 is connected to
the positive supply rail
through R2, while BI is
connected to the negative
side of the supply, and its
emitter terminal (commonly
known as the gate) is
connected to the junction
formed by timing capacitor
Cl and potentiometer R4
(which ties the emitter to the
positive- supply rail).
RESISTORS
(All fixed resistors are 1/4-watt, 5% units.)
R1- 6800 -ohm
R2-270 -ohm
R3 -22 -ohm
R4- 100,000 -ohm potentiometer
ADDITIONAL PARTS AND MATERIALS
C1- 0.1 -µF, ceramic -disc capacitor
Q1- 2N2646 or similar
unijunction transistor
Perfboard materials, enclosure, 9-16 -volt power source, wire,
solder, hardware, etc.
www.americanradiohistory.com
-I-+20-25V
PARTS LIST FOR THE
MODIFIED RELAXATION OSCILLATOR
RESISTORS
(All fixed resistors are
R1
D1
3.3K
6V
ZENER
%a
R3
-watt, 5% units.)
270t1
R1 -3300 -ohm
R2-270-ohm
R3-25,000-ohm potentiometer
CAPACITORS
C1- 0.1 -µF,
ceramic -disc
25 -WVDC, electrolytic
C3- 10- 20 -µF, 25 -WVDC, electrolytic
R2
10K
ADDITIONAL PARTS AND MATERIALS
Q1- 2N2646 or similar unijunction transistor
R4
470
SI -SP3T
switch
SPKR1 -8- or 16 -ohm speaker
Perfboard materials, enclosure, 9-16 -volt power source, wire,
solder, hardware, etc.
frequency ranges offered
by this circuit. That switch/
capacitor combination
serves as a coarse frequency adjust. Fine -frequency
adjustments for this circuit
are made via R3, a 25k
potentiometer.
When S1 is in either the A
B position, the circuit
functions as a variable, audio- frequency oscillator.
When S1 is placed in the C
position, the circuit operates as a metronome. The
circuit's frequency of operation can be reduced by
increasing the values of either C3 or R3.
or
Fig. 3. Linearity in this
version of the relaxation
oscillator has been improved
by adding a separate
charging source. By using a
higher source voltage to
charge the timing capacitor,
the entire sawtooth waveform
period occurs during a
smaller percentage of the
total charging voltage.
IMPROVED -LINEARITY
RELAXATION
OSCILLATOR
Our next
UJT
entry, see
the basic Fig. 1
circuit a bit further -adding
a separate charging
source to improve output
waveform linearity. In any
RC charging circuit that's
not driven by a constant current source, linearity is
always better at the beginning and deteriorates as
charging progresses.
By using a higher source
voltage, the timing capacitor charges more rapidly,
thereby improving the linearity of the output
sawtooth waveform. The
higher voltage won't
damage the UJT because
the voltage at the emitter
never exceeds the UJT's trigFig. 3, takes
i
Fig. 4. In addition to the constant- current charging source used
in the previous circuit, this one throws a buffer stage into the
game, allowing the circuit to drive low- impedance loads.
PARTS LIST FOR THE
CONSTANT-CURRENT RELAXATION OSCILLATOR
SEMICONDUCTORS
Q1- 2N2646 or similar unijunction transistor
Q2- 2N3906 general -purpose PNP silicon transistor
Q3- 2N3904 general- purpose NPN silicon transistor
D1-- -6-volt, 1/2-watt
Zener diode
RESISTORS
(All fixed resistors are'' -watt, 5% units.)
/
R1 -3300-ohm
R2- 10,000 -ohm
R3-270 -ohm
R4-47 ohm
R5- 10,000-ohm
R6-50,000-ohm potentiometer
ADDITIONAL PARTS AND MATERIALS
CI
100 -µF, see text
Perfboard materials, enclosure, 12- and 20-25 -volt power
-0.01-
sources, wire, solder, hardware, etc.
ger voltage, which is always
less than the operating voltage applied to B2.
CONSTANT-CURRENT
RELAXATION
OSCILLATOR
The circuit in Fig. 4 adds a
constant -current charging
PARTS LIST FOR THE
source and a buffer stage
IMPROVED-LINEARITY RELAXATION OSCILLATOR to the basic UJT circuit in
Fig. 1. In the Fig. 4 circuit,
RESISTORS
Q2, D1, R1, and R6 form a
(All fixed resistors are 1/4-watt, 5% units.)
simple constant -current
R1 -4700 -ohm
regulator. The level of reguR2- 270-ohm
lated current is set by the
R3-47 -ohm
values of R1 and R6. TranR4- 100,000 -ohm potentiometer
sistor Q2's collector supplies
ADDITIONAL PARTS AND MATERIALS
the constant charging curQ1- 2N2646 or similar unijunction transistor
rent to C1, whose value is
C1-0.01-0.22-11F, ceramic-disc capacitor
selected for the desired freC2- 25 -µF, 25 -WVDC, electrolytic capacitor
quency range. The value of
Perfboard materials, enclosure, 6-16-volt and 35 -volt power
C1 can range from .005 to
sources, wire, solder, hardware, etc.
(Continued on page 90)
www.americanradiohistory.com
71
THINK TANK
By John J. Yacono
RF Bulbs
The topic for this month,
about a new light-bulb
technology, was inspired by
a letter that I'll present
shortly. It just goes to show
you there will always be a
better "mouse trap" waiting
to be invented. Perhaps we
should re -think the wheel?
After we discuss the functioning and features of the
new light, we'll explore a
general mix of correspondence, including the
SEALED BULB
COIL
CAVITY
BASE WITH
RF TRANSMITTER
Fig. 1. The small coil
transfers RF energy from the
transmitter in the base to the
gas in the bulb.
"simplest, simplest" headlight reminder, a request
from one reader answered
by yet another, and advice
about circuits that have appeared here before. Now
let's discuss this new light
under the sun.
A BRIGHT IDEA
Just yesterday, saw an
interesting new product on
I
72
"radio" light
bulb. The globe of the bulb
was removed (apparently it
wasn't hot) during the show
to reveal a thread- spoollike inductor made from
heavy -gauge wire (see Fig.
1). would like to know how
this device works and would
appreciate any help on
1V It was a
I
this.
-Loyd J.
Crisp, Metairie,
IA
I'd be glad to pass along
what I know about the new
bulbs. However, it is important to point out that these
bulbs are in the prototype
stage and may never be
commercially available. As
to the bulb, it consists of an
RF transmitter (located in
the unit's base) and a
sealed bulb of gas with an
internal fluorescent coating.
The sealed bulb has a depression on one side (kind
of like a finger-hole in a
bowling ball) to accommodate an inductor on a
cylindrical form that protrudes from the base, as
you mentioned. The coil
couples the RF energy produced by the transmitter to
the gas within the bulb. The
RF frequency, the gas mix-
and the coating have
been selected so that the
RF energy ionizes the gas,
causing the coating to radiate light,
The bulb has some great
advantages over other fluorescent designs, let alone
incandescent units. Since
their are no filaments to
burn out, the bulb's estimated lifetime is about 30
years. As they don't require
the slightly inefficient step up transformers used in
other fluorescent schemes,
they conserve energy and
are less expensive to operhure,
www.americanradiohistory.com
ate. By virtue of the coating
and gas mixture, the bulbs
emit a more complete
spectrum of light, reducing
(perhaps. eliminating) eye
strain for those sensitive to
other forms of fluorescent
lighting. To summarize, they
are a nearly 100% efficient,
longer- lasting, healthier,
cost-effective alternative to
anything else we have.
As for me, I have only one
concern about these "super
bulbs:" it regards the RF
radiation they emit. With all
the fuss people are making
lately about being incidentally radiated (by power distribution lines, household
wiring, and appliances),
how safe are these small
RF- transmitters? I don't
know myself and I would
appreciate hearing from
anyone with input on the
matter.
By the way, this idea is not
totally new It was originally
conceived by Nicola Tesla
who thought it might be
possible to beam energy
directly to bulbs and other
devices without wires.
A WINNER
A recent issue told of
"one of the simplest" and
also the "simplest" headlight reminder. Well, here is
an even simpler "simplest"
(see Fig. 2). To install it, simply tap into the driver -side,
dome -light switch (which is
a grounding switch) and
into a positive parking -light
line and connect a mechanical buzzer to them. To
make the connection you
will probably need a couple of feet of wire and a
couple of connector
clamps.
While have used this
circuit for years, my 1990
I
Nissan pickup had this
warning system from the
factory.
-Walt Wheelock, Glendale, CA
l've received dozens of
headlight- reminder circuits
in response to the column
that you've mentioned.
t'our's has been chosen to
appear because it is the
simplest one with the highest number of good
features. Among its dis-
tinguishing characteristics
are. one -part design, it
turns off when the door
closes to further preserve
battery life, and it warns
you even if just the parking
lights are on.
season will be upon us before you know it. And as
those who live in two -level
dwellings (as do) know,
when you use air conditioning, the upstairs is
Go ahead,
put on some weight
I
often warmer than the
downstairs due to hot air
rising and cool air sinking. In
my own case, that situation
is aggravated by the thermostat, which is located
downstairs. As the lower
level cools more rapidly
than the upper level (with
lower -level temperature
causing the air -conditioner
to shut down prematurely),
the upper level is always
unbearably warm.
In an attempt to preempt
that annoying situation,
have concluded that what
need is a way to automatically control a circulating
fan so that it cycles on for
perhaps ten to fifteen minutes every hour, thereby
maintaining a consistent
temperature throughout the
structure. And if a variable
on /off cycle were to be
designed into the control
circuit, so much the better!
Unfortunately, I'm not the
designing kind. But, my
guess is that such a circuit
could be built around a
pair of 555's and a relay( ?).
If you think this circuit
could be of interest to your
readers, I'd look forward to
I
BZ1
MECHANICAL
BUZZER
TO PARKING
LIGHT LINE
TO DOOR
LIGHT SWITCH -4
Fig. 2. Can a headlights -on
reminder get any simpler
than this? If you think so
then write in.
The other circuits l've received had one or two of
those features, but not all of
them at once. Since you
were able to distinguish
yourself from such a large
group of readers l've decided to send you a little
something extra with your
book, It's the special
MC1010 chip mentioned in
the first Think Tank column I
wrote, They are hard to find
since Motorola no longer
supports them, so I though
you might like to have the
little novelty to add to your
junkbox. You've earned it.
IMPROVING
CONDITIONS
First I'd like to thank you
for providing me and many
other readers with information and projects that have
often proved to be just
what needed.
Winter may now be here,
but the air-conditioning
I
I
Introducing the improved 372 Circuit Board
Holder.
longtime favorite for circuit board work,
A
the 372 now comes with our redesigned 300
base. A new, patented, internal modification to the 300 split ball locking mecl onism
allows it to hold twice as much weight as its predecessor. Of course, the 372 still
comes with the industry's best circuit board holder, the PanaVise 315, which con
hold PCBs up to 12 inches wide (up to
28" with 30" 318 Accessory
The new PanaVise
372 Circuit Board Holder. When circuit boards are your business.
PANA
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(702) 353-2900
Sparks, NV 89431
CIRCLE
6 ON FREE
INFORMATION CARD
STATEMENT OF OWN ERSHIli
CIRCULATION
DATE
ELECTRONICS
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IN THE DOG HOUSE
This circuit (shown in Fig.
3) can be used in almost
any situation to keep the
temperature within a cer-
7
10/l5/92
suc.s
FR
One alternative is to use
something based on the
558 quad monostable timer
(see the November and
December installment of
Think Tank for more information on that chip), Another
way to go is to use a limited
version of the circuit presented by this next reader,
r
8
MONTBLY
Tank.
-Jon Hauko,
(800) 395-8002
FAX
your reply in a future install-
ment of Think
Cross Bars.)
You can even handle multiple boards when you use additional 316 Circuit Board Arms.
4,285
104.72
5,949
6,104
60,448
45,02B
157,689
r
onBLsNEn.
155,855
,+eea,
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73
Switch S1 is a mercury
switch located in an old
thermostat assembly that
mounted in the dog house.
You can adjust the temperature range by adjusting
the angle of the bulb on
the coil.
When building your own
control units, make sure the
contacts of relay K1 exceed
S1
MERCURY SWITCH IN A
THERMOSTAT COIL ASSEMBLY
Fig. 3. Here's a complete cycling heating and venting system for
any small enclosed space.
+9V
R2
1K
o
-
o
o
IC
SOCKET
Si
7
6
R3
33052
?
R1
C1
LED1
_
10'
Fig. 4. This circuit can be used to test 555 timer IC's for proper
functioning. However, does the circuit need to be modified for its
own proper operation?
DOUBLE TROUBLE
found Andy Barfield's
Telephone Recording Control circuit (from August,
the current draw of the
1992, and shown in Fig. 5)
fan(s) and lamp that you
use. Mine were old comput- and your comments about
it interesting. The reason
er- cooling AC fans that
were on hand. Neon lamps that Q2 "doesn't shut itself
were used instead of noise- off by reducing current flow
through R3" is that the Q2
suppressing capacitors for
collector -emitter junction
no special reason. It just
does not achieve full satlooks neat when the fans
uration. The saturation
go off and the neon bulbs
voltage will remain just
flash. Just be sure to use
above the minimum base enough neon lamps for
emitter forward barrier poyour fan motor(s) or the
counter EMF will burn them tential of Q2 (about 0.6
That's because the saturaup.
tion voltage is slightly
The heating lamp, a reggreater than the sum of the
ular 60 -watt light bulb,
should be mounted in rela- 2 base-emitter forward barrier potentials (about 1.2 \1.
tion to the thermostat coil
to give the desired time you The circuit is thus a stabilized self -limiting linear
want the area to receive
amplifier.
heat. Mounting it far away
This phenomenon usually
from the thermostat will alpresents a common problow more heat to escape
lem when using Darlington into the area; mounting it
pair transistors. For example,
closer will cause the relay
in low- voltage motor -conto switch on and off more
TO TELEPHONE
microcassette recorder,
which uses only 3 volts, the
high saturation voltage of
Q2 could result in a slowing
of the motor, and distorted
sound on playback. It may
be possible to give 02 a
little extra "boost" to reduce
SOME MODIFICATIONS the collector -emitter saturabuilt the 555 timer tester tion voltage by connecting
a large -value resistor be(Think Tank, October 1991)
tween the positive output of
shown in Fig. 4, but could
the bridge, and the collecnot make it work until
changed R3 from 330 -ohms tor of Q1.
The value of the resistor
to 9500 ohms. All other
should be low enough to
parts in my unit are very
provide Q2 with the extra
close to the indicated valbase-emitter current reues. It now works quite well
quired for collector- emitter
and is very useful.
really enjoy Think Tank
saturation of about 0.1 volt
Keep it up.
with a bridge output of 5
-Howard Fogle, Kavolts. However, it should not
tonah, NY
(Continued on page 91)
TX
shouldn't feel awkward about your circuit.
Your wife had a good idea
Mat another reader will
benefit from. Your book is
on the way.
You
LINE
o
BR1
RING( -)TIP
(
+)
AMP
100PIV
R3
1K
1
02
MPS5172
R2
1MEG
K
D1
01
20V
MPS5172
I
'
R1
PL2
r
Cl
,
41
.01
100K
TO
REMOTE
C2
.01
PL1
TO AUX.
k
Fig. 5. This recording control relies on the doubled minimum
saturation voltage of the Darlington pair to keep from turning off
I
I
tain range. use it in a
doghouse for year -round
temperature control. (My
I
74
I
trol circuits, such as in a
frequently.
-Jim Austin, Arlington,
o
experienced could be due
to the fact that you used
parts other than those originally specified in other
places in the circuit.
\.
27052
A
Thanks for the information. The problems you've
wife made me do it.) It can
be easily reconfigured to
meet many needs.
www.americanradiohistory.com
!
DX LISTENING
By Don Jensen
Targeting the
World
There's an easy way, and
a hard way, to do most
things. And there is something to be said for each
approach. As a shortwave
listener, doubtless you have
your goals. It may be to
hear as many different stations as you can. Or,
perhaps, the challenge is to
tune in a certain as -yet
unheard broadcaster half a
world away.
But
logging all con-
tinents-Africa, Antarctica,
Asia, Australia /Oceania, Eu-
rope, and North and South
America-can also be a
very difficult task if you limit
yourself to other stations in
those areas, such as low powered, domestic, or
home -service shortwave
broadcasters.
When it comes to HAC
(Heard All Continents),
there's an easy way, and a
hard way. So, for beginning
and veteran DX'er
alike, here are some different ways to accomplish
that HAC goal. There are, of
course, many other stations
that would fit the bill, as
well. The following is just a
SWL
"VOICE OF
THE
WORLD"
sampling:
AFRICA:
7.490 mHz
41 METER BAND
This station sticker is sent, along with a QSL card, to those
SWL's who report hearing WJCR, a new US shortwave station.
beginning SW
the self-selected target is to tune in,
and then collect QSL -card
verifications from at least
one world-band station on
each of the continents.
For many
DX listeners,
While an interesting goal, ifs
not too difficult to achieve
in this age of super -highpowered shortwave transmitters. With a bit of effort
and some time, one can
accomplish that even with
a fairly unsophisticated receiver.
Egypt-Radio Cairo
shouldn't be difficult as a
starter. For years, this North African SW'er has been a
regular on 9,475 kHz during
the evening hours. You will
find it easily if you tune in
shortly before 0300 UTC,
when its Arabic -music programming is a dead
giveaway. English programming begins on the hour.
Angola-Emissora Provincial do Lobito, a difficult
catch, is one of the seldom heard regional stations
from this southern African
country. It has been logged
with Portuguese -language
programming in the eastern U.S. on 7,151 kHz at
around 2230 until 2304 UTC
sign off. It relays the Radio
Nacional service, but has
been heard with a local
identification for Radio
Emissora Regional Lobito at
about 2240 UTC.
ANTARCTICA:
Well, there are only two
shortwave stations that
www.americanradiohistory.com
have operated from this
frozen "bottom- of-theworld" continent, so the
choices are limited. The
easier of the two is clearly
the Argentine Army's Radio
Nacional Arcangel San
Gabriel, LRA36, at Base Ant-
artida Esperanza (which
translates from Spanish as
Antarctic Base "Hope ").
When it is on the air, which it
is periodically, it can be
heard with quite good signals at times on 15,475 kHz,
in Spanish from 2100 to
2300 UTC.
The other Antarctic SW
station, which has been
logged even more sporadically in North America,
is the American Forces Antarctic Network station at the
U.S. research station at
McMurdo. Programming is
mostly local -deejay pop music shows. The frequency
is 6,012 kHz, and seems best
heard from around 100 to
1200 UTC when it is active.
ASIA:
China -Radio Bejing is
hard not to hear. This is one
of the world's major shortwave broadcasters, and it
operates many transmitters
on many different frequencies. Look for their English
programming, which is
beamed to eastern North
America at 0000-0100 UTC
on 9,770 and 11,715 kHz;
and to western North America on 0300-0400 UTC, on
the same two frequencies,
plus 9,690 kHz.
Bhutan-Bhutan Broadcasting Service, from
Thimpu (the capital city of
this tiny Himalayan kingdom), is a prize catch for
any DX'er. It has been
heard as far east as Ontario, however, at around
1300 to 1345 UTC, or later,
75
on 5,025 kHz.
AUSTRALIA/OCEANIA:
Australia -Radio Australia is a good choice,
since it operates with decent power from about
0000 to 0400 UTC on 21,740
kHz; 0400 to 0830 UTC on
15,240 kHz, and 0830 to
1500 UTC on 9,580 kHz.
Bougainville -Site of a
bloody battle during WW2,
Bougainville is part of the
far -flung island nation of
Papua, New Guinea. But
the local inhabitants are in
a state of rebellion against
the distant government. The
clandestine SW station,
Radio Free Bougainville has
been heard with some difficulty by North American
DX'ers on 3,880 kHz, between about 0800 and
1100 UTC.
EUROPE:
Italy-The choices for an
easy European logging are
many. I've selected Italy's
Radiotelevisione Italiana, whose English
RAI,
programming is beamed to
North America at about
0100 UTC on 9,575 or 11,800
kHz.
Scotland -There are no
licensed shortwave stations
in this northern part of the
United IGngdom, but there
are a couple of now -andthen illicit "pirates" on the
air. One whose low -power
signal has been known to
jump the Atlantic is
Weekend Music Radio,
which uses different frequencies at different times.
One frequency that you
might try is 15,044 kHz on
the weekends at around
0100 UTC.
NORTH AMERICA:
United States-While
there are a number of different shortwave voices that
could qualify as easily
heard, one of the newest
on the air is a relatively
NO -CODE
HAMARE
LICENSES
HERE!
All About Ham Radio by Harry Helms,
AA6FW, tells how to get your codefree
ham license and talk to the world.
In over 300 pages, you'll learn about:
packet (computer-to- computer) radio
ham television
using ham radio satellites
contacting stations in foreign countries
and many other exciting topics explained
in a friendly, humorous style without a lot
of math and or technical jargon. If you've
been wanting a ham license, this is the
book you've been waiting for!
Only $19.95 at bookstores and radio
equipment dealers. Or order direct from
HighText! Add $3 shipping ($4 to Canada,
$5 elsewhere). CA please add sales tax.
U.S. funds only please.
IlighText
7128 Miramar Rd., Suite 15L
San Diego, CA 92121
76
small religious broadcaster
with a big signal, WJCR
World Wide in Upton, Kentucky. Try for this one at
almost anytime on 7,490
Blvd., Farmingdale, NY
11735.
Jack DeAntonio of Coral
Gables, FL, has an opinion
question for me. "What," he
asks, "do you think is the
kHz.
most significant thing that
Canada -CKFX in Vanhas happened to SWL'ing in
couver, British Columbia,
the past few years?"
operates on 6,080 kHz with
Unquestionably, Jack, it is
a mere 10 watts of power. It
the drastic and dramatic
is a tough log in most of
changes that have ocNorth America. Your best
chance for hearing this one curred in shortwave
broadcasting within the forwould be during the wee
mer Soviet Union. With the
hours of the morning between midnight and dawn. disappearance of the old
monolithic USSR, with its
SOUTH AMERICA:
huge, centrally directed
Ecuador -Flat out, the
broadcasting apparatus,
easiest way to log South
shortwave radio has been
America is HCJB in Quito.
turned on its ear.
There is a good chance
Within the new "comthat HCJB will be for most
beginning SWL's what it was monwealth," there remain
for me nearly 46 years ago, hundreds of high -powered
SW transmitting facilities
the first shortwave station
and no central controlling
we ever heard. But if you
haven't found it yet, try tun- organization. What we now
are seeing are all sorts of
ing 9,745 or 15,155 kHz
new broadcasting operabetween 0030 and 0500
tions, using the existing
UTC.
stations. Some have been
Surinam-Radio Apintie
leased to western religious
on 5,006 kHz has been an
extremely tough logging for broadcasters. Some have
come on the air as fledgmore than a few years. It
ling commercial stations.
has been running a mere
50 watts of power in a noisy There are all sorts of new
area of the 60 -meter band. stations coming on the air.
It's a fun time to be
But it was heard not too
long ago in the eastern U.S. SWL'ing!
at around 0400 UTC.
DOWN THE DIAL
It's up to you whether you
Here are a couple of
want to try the easy or hard
eastern European stations
path to HAC.
to tune for:
BULGARIA -Radio Sofia
IN THE MAIL
has been reported with EnYour letters are always
glish programming from
welcome. What are you
0300 to 0400 UTC on 9,850,
hearing on the shortwave
11,720 and 15,160 kHz.
bands? What are your faCROATIA-Zagreb's
vorite stations or QSL's? Do
you have questions or corn - Croatian Radio features Enments about SWL'ing? Drop glish- language news shortly
after 0600 and at 0800 UTC.
me a line in care of DX
Try 9,830 kHz. They've also
Listening, Popular Elecbeen noted on 21,480 kHz
tronics, 500 -B Bi- County
at about 1200 UTC.
UKRAINE -The Radio
*Credits: Dan Ferguson, VA;
Bob Padula, Australia; Fred Bar- Ukraine World Service, forkley, Richard Langley, Canada;
merly "Radio Key," can be
Art Magnussen, MN; North
heard at various times beAmerican SW Association, 45
tween 0200 and 0730 UTC
Wildflower Road, Levittown, PA
on 15,195 and 17,690 kHz.
19057.
www.americanradiohistory.com
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79
HAM RADIO
By Joseph J. Carr, K4IPV
I
Some More
Potpourri
t
SHIELD
I-
rom time to time, like
to take a look at my
mail bag and answer some
questions posed by readers.
This "potpourri" usually rambles from one topic to
another, as does the actual
mail. But first, however, let
me say thank you for all of
the mail that I've received.
With only a couple of exceptions, the mail has been
running very positive. am
I
L2
.3µH
L1
.3µH
,
J2
RCVR
J1
Y
ANT
Cl
C2
110pF
110pF
L
---
C3
110pF
C4
110pF
A
L1
i
3.3µH
J2
RCVR
J1
ANT
Cl
C2
7.7pF
7.7pF
L
B
These two 10-meter -plus LPF circuits, which are designed
to remove VHF signals that can cause receiver front -end
overload, can be made small enough to fit inside many
transceiver cabinets. The LPF in A is a two -section LC filter that
has a cut -off frequency in the 32 -MHz region. The one in B is
simpler, but has a less steep roll -off characteristic above the cutofffrequency.
Fig.
1.
glad that shortwave listeners, monitor buffs, and
general electronics enthusiasts all find this column so
useful.
LOW -BAND VHF
SIGNAL'S
80
One reader complained
that the 15- and 10-meter
bands were compromised
by a local FM broadcasting
station (88- to 108 -MHz
band). It seems that he
lived only a few blocks from
the FM "blowtorch," and it
overloaded the front end of
his receiver. Many modern
receivers do not have terribly selective front ends.
They use a wide bandpass
filter rather than peaked,
resonant circuits (which was
the former way of doing the
job). As such, some of those
"wonder-boxes" seem eager to overload in the
presence of strong local
signals.
The solution to the pioblem is the same as I've
harped on for many years:
use a lowpass filter (LPF)
with a cut-off frequency (Fc)
that's above the 10 -meter
band, but sufficiently below
the frequency of the offending signal that it is way
down the roll -off curve. All
hams should use some sort
of lowpass filter in the antenna line in order to
prevent NI from your transmitter (the "good neighbor
policy" is best).
However, I've seen some
cases where a lowpass NI
filter messes up the band pass filters that are used in
the output circuits of modem solid -state rigs. As long
as both the output and
input have impedances of
50 -ohms, and as long as
the entire system is imped-
ance matched, then the
filter should cause no harm.
But that ideal is seldom
reached in practical cases.
There have been some
problems when certain
brands of LPF's are used
with some transmitters. The
problems seem aggra-
vated when certain
antenna -tuning units are
used in the line as well. If
www.americanradiohistory.com
you want the receiver to be
less sensitive to all forms of
VHF signals (including channels 2-5 1V FM BCB, 6 -meter
hams, and "low- band"
landmobile VHF -FM communications stations), then
use a NI filter in the output
of your transceiver.
However, if you are not
able to use such a filter
because of mismatch problems in your rig, or if you use
a separate receiver, then
try one of the circuits in Fig.
1. Those circuits are 10meter -plus LPF's, and will
probably do the job. You
can make them small
enough to fit inside many
transceiver cabinets on the
receiver side of the T/R relay.
Of course, with a separate receiver that's not a
problem. Build them in an
outboard shielded box and
be happy. The LPF in Fig. 1A
is a two- section LC filter that
has a cut -off frequency in
the 32 -MHz region. The capacitors (C1 -C4) should be
silvered mica or NPO ceramic-disc units. The
inductors can be either
store -bought (try Digi -Key,
677, Thief River Falls,
MN, 56701 -0677; Tel.
1- 800 -344 -4539) or made
P.O. Box
from Amidon Associates
(P.O. Box 956, Torrance, CA
90508) toroidal cores. Try
Amidon's T-37 -6 (yellow)
core wound with ten turns
of #26 enameled wire.
The other filter is simpler,
but has a less steep roll -off
characteristic above the
cut -off frequency. It will
nonetheless work for attenuation of FM signals. The
small 7.7 -pF capacitors
should be either ceramic disc or tubular- ceramic
units. The inductor can be
,
ANT
Cl
C2
C3
.002
001
001
K
K
L1
L2
3.3µH
3.3µH
Another "dyn -o- mite" receive antenna that doesn't
J2
RCVR
Fig. 2. This HPF filter circuit can be used in cases where AM
broadcast-band interference is a problem.
wound on the same core
as above (Amidon T- 37 -6),
but requires 33 turns of wire.
That's a lot of turns for a
T-37 -size core, so use #30
wire. Alternatively, use a
T-50 -6 (yellow) core, wound
with 29 turns of #26 wire.
In cases of AM broadcast-band interference, you
can use the circuit of Fig. 2
(which I've mentioned before in this column). I've had
good results using both the
T-50 -2 (red) and T-50 -6
(yellow) cores. In the case
of the T-50 -2 core, only 26
turns of #26 wire are
needed.
By the way, when give
wire sizes for filters, the wire
size is for reference only.
The filter will work the same
with other wire sizes if you
can get the right number of
turns on the form. It's the
turns count that counts, not
the size of wire (except in
transmitters, where high
power is involved).
I
Remember, these filters
are for receiver applications only. The higher power
filters needed for transmitters use heavier duty
capacitors and much
heavier inductors.
WHAT'S THE "LAW OF
RECIPROCITY ?"
Well, it's not some flaky
New Age concept (George
Gurdieff notwithstanding),
but rather a properly of
antennas. The "Law of Reciprocity" concept means
that an antenna works on
receive exactly as it works
on transmit. In other words,
if it has 5.5-dBi gain on
transmit, it will also have
5.5 -dBi gain on receive. The
transmit and receiver
azimuthal and elevation
patterns remain the same
in both modes.
There is no known case
where the Law of Reciprocity for Antennas is
violated. The only case
where it looked like such an
Earth -shaking breakthrough
might have occurred
turned out to be a hoax. It
appeared in the April issue
of a popular ham -radio
magazine.
The Law of Reciprocity
does not, however, imply
that all antennas are "created equal" in regards to
the receive and transmit
modes. It can be argued
that the major antennas
(dipoles, yogis, quads, and
verticals) are pretty nearly
matched with respect to
receiving and transmitting.
But that is not universally the
case: For example, the
small loop antenna is great
for small -space reception
of low frequencies (75meters down to VLF), but
transmits for squat. I've used
a 24 -inch square loop to
cut down the crud on 75meters by nulling out some
of the interference. That
scheme works well when
the interference is arriving
from an angle that's different from the desired
station (it doesn't work well
at all if your location lies in
a line that also passes
through both the interfering
and the desired station).
work as well on transmit is
the Beverage antenna. This
claim may seem contradictory because a Beverage is
similar to a long -wire beam
antenna. But the Beverage
works best on receive over
poor ground, and is thus
somewhat lossy for transmitting. It's not a total bust,
however, and may have
more gain than a dipole,
but it doesn't work quite as
well on transmit as receive.
SECOND RECEIVER
A little earlier, mentioned that some hams use
a second receiver on the
HF bands. Why, you ask?
Well, there are several reasons. DX'ers like to keep
track of other DX opportunities on the band while
waiting their turn in a pileup. The second receiver
I
also makes sense when the
pile-up is on one frequency
(you eavesdrop on the
competition) and the DX
quarry is on a slightly different frequency.
To be maximally effective
the second receiver must
be at least as good as the
receiver in the transceiver.
One recent model that is a
very good radio is the R.L.
Drake (P.O. Box 3006,
Miamisburg, OH,
45342;513- 866 -2421) Model
R8. That American -made
radio receiver walks with
the best of them, and is a
pleasure to operate. recently test drove one and
was most pleased.
We welcome your letters,
comments, suggestions, etc.
Send all correspondence to
Ham Radio, c/o Popular
Electronics, 500 -B Bi -CounI
ty Blvd., Farmingdale,
NY
11735.
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81
SCANNER
SCENE
adio Shack's Realistic
By Marc Saxon
gl,Patrolman
kicks off the new year with
a field goal. It consists of an
A Couple of
Winners
attractive mobile scanner
that reprises a feature we
always liked when it was
available-service search.
Pressing one of the five
front -panel buttons marked
POLICE, ARE, AIR, WEATHER,
MARINE,
and
instantly causes the
scanner to begin searching
(at 19 channels per second)
Patroiman
.
A..x
<<,
..a,
i
-.a z-m ., , ratte
_...
S4Fwe
e
.0174M.
This
new mobile scanner
sells for $199.95,
PRO -2026
PPOÇA/VXMASI.
The new Radio Shack Realistic PRO -2026 offers service search.
all frequencies assigned to
the selected service. You
don't have to program
search frequency limits for
those services on any
and can
be seen at your nearest
Radio Shack. We were very
impressed with the
PRO -2026 and found that
the service- search feature
was a much used function
at our installation. We also
liked that the light in the
backlit LCD could be turned
off, which we appreciated
while driving at night. Good
set!
hear are in only one direction, then stick it on your
roof aimed in that direction
for long -range reception.
Or you can mount the yagi
on any TV antenna rotor
and then aim it in the many
directions that suit you. This
antenna really pulls them in
from far away.
The 800-MHz -band yagi
costs $75 (plus $4 shipping),
from the Cellular Security
Group, 4 Gerring Road,
ANOTHER
Gloucester, MA 01930. Their
INTERESTING
toll -free number is
PRODUCT
1- 800 -487 -7539.
For the many readers
who are deeply into
CALLING DR.
monitoring the 800-900 SCANNER!
MHz band, we stumbled
We have always been of
across something really
the opinion that the least
useful- a powerful, 11-elemonitored local emergenment, rear -mount 800-900 cy services relate to
MHz (only) loop vagi beam
medical communications.
antenna for base station
People load up on police
use. It's fully assembled, so
and fire communications
all you need do is attach a
coaxial cable with a Type N channels, but somehow
don't take good advantage
connector to the beam,
of this third partner in local
and feed the signals into
emergency service proyour scanner.
viders.
The PRO -2026 has 100
memory slots, arranged in
Frequencies 155.325,
155.355, 155.385, and
155.40 MHz are designated
five banks of 20 channels
in
bands.
82
If the 800 -MHz band stations that you most want to
each. The frequency range
is 29 to 54 MHz, 108 to 174
MHz, 406 to 512 MHz, and
806 to 956 MHz. The cellular
bands are locked out at the
factory. The IF frequencies
are 10.8 and 450 kHz. Scan
speed is 14 channels per
second, with an optional
two- second delay for each
channel. There's also a priority channel that's sampled every two seconds.
yagi on
those distant stations!
Try this 800 -MHz
www.americanradiohistory.com
the U.S. for hospitals communicating with
approaching ambulances.
Communications on those
channels most often consist
of the ambulance personnel advising the hospital of
their expected arrival time,
the nature of the medical
problem of the patient
being transported, the patient's symptoms and vital
signs, plus any special medical conditions that exist.
Scanner owners tend to overlook the exciting medic frequencies.
Among the frequencies
commonly used to dispatch
ambulances are 155.28,
155.34, 460.525, and 460.55
MHz, although others might
be used in specific communities. Sometimes fire
departments have their
own medical vehicles, and
those might be dispatched
on fire -agency frequencies.
Ambulance crews, as well
as medic teams using portable equipment, often
need to send bio- medical
telemetry data. Most often,
that consists of an EKG sent
to a hospital for quick medical evaluation by a
physician who can advise
on medication to be immediately administered. Those
communications take
place on any of eight
channels, known as "MED -1"
to "MED -8," that run from
463.000 to 463.175 MHz
(with 25-kHz spacing), with
the mobile and portable
units operating on paired
frequencies from 468.000 to
468.175 MHz.
Some ambulance crews
have low-power handheld
transceivers that offer short
range. Those units are able
to communicate with hospitals only via mobile
repeaters installed in the
ambulances. The hand helds generally use 150.775
and 150.79 MHz to input to
the mobile repeaters.
Hospitals with helipads
often have 123.05 or
123.075 MHz available (in
Canada, 129.275 MHz is
popular) for communicating with arriving medevac
helicopters.
All of those frequencies
should be entered into your
scanner and checked for
activity local to your area.
There are other medic frequencies as well. You
should check for activity on
33.02 to 33.10, 37.90 to
37.98, 45.92 to 46.04, 47.46
to 47.66, 155.175, 155.205,
155.22, 155.235, 155.265,
and 155.295 MHz. Some frequencies below 38 MHz are
shared with stations in the
Highway Maintenance Radio Service.
Although not precisely
medical, communications
connected with search and
rescue activities are related
to this area of monitoring.
Good frequencies to
monitor for those communications include 122.9, 123.1,
148.15, 155.16, 156.30,
157.05, 157.175, 282.8, and
381.8 MHz.
Also remember that 47.42
MHz is the primary American Red Cross frequency.
MOVE OVER, BATMAN!
It's been no secret in recent years that in many
metropolitan areas, unlicensed two -way radio
users abound on the business and other VHF
frequencies. The FCC is too
understaffed to adequately
crack down on the problem, and, besides, FCC
personnel say they don't
get paid enough to go into
some of the rough neighborhoods where the
bootleg stations are located in order to pinpoint
their locations and shut
them down. Licensed two way radio users, nevertheless, complain about their
communications being disrupted by the bootleg
stations.
In Los Angeles, Van
Williams (who played The
Green Hornet on 1V more
than 25 years ago) got fed
up with the abuses on the
frequency of his business
radio system so he took
WRITE TO US
Don't forget, we always
look forward to hearing
from you. Our address is
Scanner Scene, Popular
Electronics, 500 -B Bi -County Blvd., Farmingdale, NY
11735. Send us your scanner
questions, frequencies, photographs, comments and
news clippings.
Enter A World Of Excitement with a Subscription to
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ectronics
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So if you love to build fascinating electronics, just call toll free the number below to
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www.americanradiohistory.com
weal. hwelPlw
matters into his own hands.
He got into his van, which
was equipped with direction- finding equipment,
and tracked down the guy
who was chopping up his
frequency with unlicensed
chatter.
After turning in the bootlegger, Williams said that it
was the first time in years
that he was able to use the
channel without interference. Maybe we need
the Green Hornet in every
large city.
PM- EASTERN
APEA3
STANDARD TIME)
83
ELECTRONICS
LIBRARY
1992-93
Educational
Systems
Catalog
from Heathkit Educational
Systems
Edited by: Teri Scaduto
This two -in -one catalog is
aimed at electronics enthusiasts
as well as vocational and technical teachers and industrial
training managers. Half the catalog is devoted to individual
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The "Individual Learning
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to laser, microprocessor, and
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Each course is designed to lay
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hands -on experience on which
students can build as they learn
new concepts and take on real life applications.
Highlighted is Heathkit's new
Version 2.0 of their computer aided instruction series of electronics training courses. Using
the power of PC's to make
learning electronics easier and
faster than ever, the courses are
available in the topics of DC
Electronics, AC Electronics,
Semiconductor Devices, and
Electronic Circuits; soon- to -bereleased computer-aided
courses include Digital Techniques and Troubleshooting.
The 1992-93 Educational
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request from Heath Company,
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49023; Tel: 1-800 -44- HEATH.
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YOUR QRP OPERATING
COMPANION
by Brad Wells, KR7L
The hobby of QRP-ham operating with an output power of 5
both challengwatts or less
ing and exciting. Most amateur
radio contests have a QRP entry class, and hundreds of hams
from around the world participate. In fact, many hams have
managed to work more than 100
countries QRP to QRP.
This book is designed to help
QRP'ers get the most from their
hobby. No special rig or expensive and complicated equipment
is needed. Taking a firm stance
-is
contains thorough explanations
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cover operating techniques and
explain how to maximize your
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list QRP clubs and nets, and
contests that include QRP categories.
Your QRP Operating Companion costs $6.00 and is
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by Ronald
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TTLX
ALL THREE GUIDES,
Vols 1, 2, & 3
(save $6.00)
ST\-- oe
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Grp
Each volume provides
a
exercises that illustrate the concepts and procedures of solid
modeling in progressive levels
of complexity.
Solid Modeling With AutoCAD, Second Edition, costs
$29.95. A companion diskette,
which includes sample drawings
from the book, AutoLISP programs for AME, and batch files
that reduce various commands
to single- keystroke operations,
is available for $49.95. Both are
available from Ventana Press,
P.O. Box 2468, Chapel Hill, NC
27515; Tel: 919- 942-0220; Fax:
919-942 -1140.
comprehensive list-
ing of all commonly used TTL integrated
circuits within the range of types noted. The
combination of three volumes covers 7400
through 7430640 TTL products from all major manufacturers. All current families are
covered: standard, low power, Schottky, low
power Schottky, advanced Schottky, ad-
CIRCLE 90 ON FREE
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1992 -93 EQUIPMENT,
TOOLS & SUPPLIES
CATALOG
THE CB RADIO
HACKER'S GUIDE
from Print Products International
by Kevin Ross
This catalog contains 68 pages
of discount test and measurement equipment for electronic
production, maintenance, and
service. Featured are items from
such major manufacturers as
This book tells readers exactly
which screws to turn, which
wires to cut, and which components to add to help
substantially improve the performance of their CB's and add
updated controls, features, and
capabilities. It also reveals
methods of unlocking those hidden functions that were never
activated at the factory and
methods of adding new features
that the factory forgot to include.
vanced low powered Schottky, high speed
and fast Schottky. There are eight sections to
the book. Section 1 illustrates the device
schematic using a clear and simple logic diagram. Next a brief description of the components, providing quick reference to the
internal structure. The next section details
input signals or levels at individual pins. The
fourth section lists major applications and is
followed by a summary of essential data.
Below this, a table indicates the TTL families
in which the device is available, and finally,
device description and type number are highlighted for easy reference. A manufacturer's
index at the back of the book shows in tabular
form which companies manufacture each
package.
MAIL TO: Electronic Technology Today, Inc.
P.O. Box'240
Massapequa Park, NY 11762 -0240
included is practical advice on
how to diagnose CB problems,
how to test microphones and
wire microphone plugs, and
other useful information to enhance your CB station and
operations.
The CB Radio Hacker's
Guide costs $18.95 plus $3.50
shipping (NY residents must
add $1.61 sales tax) and is
published by CRB Research
Books, Inc., P.O. Box 56, Commack, NY 11725.
+K, Fluke, Avcom, Hitachi,
Leader, Pace, Kenwood, Philips,
and more. Product categories
include oscilloscopes, power
supplies, meters, EPROM systems, static -control products,
spectrum analyzers, and surface -mount equipment. Also
featured are replacement parts
and new lines of closed- circuit
B
TV systems.
Expand Your CO Radio's Functions'
?'''fl',,''
w
C41^
x
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HaA1px
w".
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Charts show how to tweak and
peak existing circuits so that
they perform at their maximum
potential for best power output,
full modulation, best AGC and
squelch action, and finest all around operation. The book
shows how to add RF and
microphone gain controls, a
noise blanker, bright/dim control, switchable audio tone, high/
low transmitter power, a modulation meter, and more. Also
www.americanradiohistory.com
The 1992-93 Equipment,
Tools & Supplies Catalog is free
upon request from Print Products International, 8931
Brookville Road, Silver Spring,
MD 20910; Tel: 1-800 - 638 -2020
or 301 -587-7824; Faxa
1- 800 -545 -0058 or
301 -585 -5402.
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NEW PRODUCTS
Video
Information
System
Radio Shack has entered the
multimedia interactive market
with the Memorex MD -2500
Video Information System, or
VIS. The VIS unit, which connects to any TV set and can
also be hooked up to a stereo
system, plays interactive VIS
discs that provide electronic access to reference books,
instructional materials, learning
and action games, and a variety
of educational programs. A
wireless controller allows users
to interact with the pictures,
voice, music, and animation sequences contained in VIS
applications. The system pro-
vides high -quality pictures with
color resolution of up to 16
million colors. Its audio system,
which can be connected to a
home stereo system using optional cables, is digitally
synthesized and provides digital
stereo sound from both VIS
discs and audio CD's.
The MD -2500 comes with a
VIS version of Compton's Multimedia Encyclopedia, which
includes all 26 volumes plus a
complete Webster's Intermediate Encyclopedia on one disc. A
"Save -It" cartridge is included
for saving game scores or preserving electronic "bookmarks"
in reference books. Options include a second, wired, hand
controller, and a modem for
connecting to on -line information services.
The Memorex MD -2500 VIS
system (Cat. no. 16 -376) is
available for $699 at Radio
Shack stores nationwide. VIS
software titles range in price
from $29.95 to $79.95. For
more information, contact Radio
Shack, 700 One Tandy Center,
Fort Worth, TX 76102.
1001 SOP -!00 501PLEX/OUPLES SMART PATCH
41
S)
SS
PLC TEL
PER
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PERSONAL AUTOPATCH
j -Coms Model SDP-600
Simplex/Duplex Smart Patch is a
microprocessor-controlled interface between a VHF /UHF
transceiver and a telephone line
that allows the user to make
and receive telephone calls
from any H/T or mobile rig
within range of the base station.
Installation consists of connecting the autopatch to the
rig's microphone and speaker
jacks and plugging in an RJ -11
telephone jack. Control and programming is done by DTMF
tones issued from the remote.
Separate user -programmable
access password codes can be
set up for local and long-distance dialing. An external logic
output, which can be used to
control a repeater or to drive a
relay for the control of any ham shack accessory, is provided.
An automatic CW (Morse code)
identification transmission occurs at the beginning and end of
each call.
The SDP -600 can be used in
full duplex mode with a dual band transceiver. Using full duplex, both parties can hear each
other at the same time. Simplex
mode may also be used with
VOX control based on sampling
both the telephone and receiver
audio signals or with optional
carrier detection. Turn -around
beeps indicate the end of each
transmission.
With the reverse patch option
enabled, incoming calls will
cause a short ring -out over the
air. The user then can answer
the call using his access password code. Ring -out activation
can be adjusted from one to
nine rings.
www.americanradiohistory.com
The Model SDP -600 auto patch is available at an
introductory price of $199.95.
For more information, contact jCorn, Box 194, Ben Lomond,
CA 95005; Tel: 408 -335 -9120;
Fax: 408 -335 -9121.
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DC POWER OUTLET
If you need a neat and easy way
to distribute 12VDC to various
transceivers and accessories,
the MFJ-116 Deluxe DC Power
Outlet might be the solution.
The multiple DC power-outlet
strip features eight terminals for
connecting rigs and keyers,
TNC's, tuners, and other gear.
4,4-4-
iw
Output voltage is continuously
monitored on its built -in voltmeter, making it a handy power
outlet for electronics hobbyists,
too. The MFJ -1116, which can
be installed at the rear of a desk
to eliminate the tangle of "hay wires," features eight outlets
with heavy-duty, five -way binding posts with standard spacing
for dual banana jacks. The outlets are also RF bypassed. The
strip also has a master power
switch and a 15 -amp fuse.
The MFJ -1116 Deluxe DC
Power Outlet costs $44.95. For
additional information, contact
MFJ Enterprises, Inc., P.O. Box
494, Mississippi State, MS
39762.
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87
SOUND -ENHANCEMENT
COMPONENT
The Retriever is a lower- priced
version of Hughes Aircraft Company's SRS three-dimensional
sound -enhancement component for home audio and video
systems. The stand -alone unit
uses a new VLSI chip that
produces a realistic surround type sound from conventional
recorded or broadcast sources.
The chip uses Hughes' patented
Sound Retrieval System (SRS)
technology, which expands the
sound signal so that it appears
to emanate from outside the
physical limits of the usual two
loudspeakers. The Retriever retains the same user-control
features and stereo enhancement effect of the original model
AK-100, but lacks the three -way
LED display that is found on the
earlier model. At 23/8x 161/2 x 7
inches, the Retriever also is
smaller than the AK-100.
The Retriever sound- enhancement component has a
suggested list price of $179. For
further information, contact
Hughes Audio Products, Division of Hughes Aircraft
Company, P.O. Box 7000,
Rancho Santa Margerita, CA
92688; Tel: 1- 800- 2HEAR3D
(1- 8000 -243 -2733).
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HANDHELD LASER
POINTERS
Harnessing the power of micro laser technology, the Laser
PowerPointers are the smallest,
brightest handheld lasers available to consumers today,
FAC T CARD
according to Lyte Optronics.
The line includes the Laser
PowerPointer (pictured) and the
PointWrite Laser Pen, which
combines a laser pointer with a
writing instrument -the Space
Pen from Fisher. Both PowerPointers use laser light to
produce a brilliant orange/red
dot that can be seen from 150 to
300 yards away.
The Laser PowerPointer is
available in black anodized aluminum, 24 -carat gold plate, and
titanium; custom finishes and
laser engraving also are available. Weighing just one ounce
and measuring five inches in
length and one -third of an inch
in diameter, the pointer fits conveniently in a shirt pocket.
Power is provided by two 1.5
volt batteries.
Laser pointers have many applications other than as
presentation tools. Engineers
and architects use them to point
out specific features of a structure without climbing ladders;
police officers to survey a crime
scene without disturbing evi-
ALL YOU NEED to know about
electronics from transistor packaging
to substitution and replacement
guides. FACTCARDS numbers 34
through 66 are now available. These
beautifully -printed cards measure a
full three -by -five inches and are
printed in two colors. They cover
a
wide range of subjects from Triac circuit/replacement guides to flip-flops,
Schmitt triggers, Thyristor circuits,
Opto- Isolator /Coupler selection and
replacement. All are clearly explained
with typical circuit applications.
WANT TO EXPAND your knowledge of electronics? Do it the easy way
dence; doctors and medical
sales consultants to identify anatomical structures and surgical
tools in a sterile field; and
plumbers, electricians, and contractors to illustrate where a
pipe or wire will be installed.
The Laser PowerPointers
have retail prices starting at
under $200. For more information, contact Lyte Optronics,
3015 Main Street, Suite 450,
Santa Monica, CA 90405; Tel:
310 -450-8551; Fax:
310 -392-1754.
CIRCLE 106 ON FREE
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by studying the Electronics Fact
Cards. Do you travel to and from your
job each day? Drop a handful of cards
in your pocket before you leave, and
the bus becomes a schoolroom! At
home, you can build some of the projects and not only have fun building and
using them, but learn how they work at
the same time.
YOU'LL BE AMAZED both at how
rapidly you learn with these cards, and
how easy it is to understand. These
new cards are available right now.
Don't miss out. Send your check or
money order today.
FACTCARDS -Facts
at your fingertips for
Experimenters and Project Builders!
Please send one copy of FACTCARDS at $3.50. Shipping $1.00 (U.S. and Canada only).
Please send
copies of FACTCARDS. Total cost is sum of copy price and First Class
postage and handling cost multiplied by number of card sets ordered.
New York residents add sales tax to total cost of each order.
Allow 6 -8 weeks for the material to arrive.
Please print
Jampacked with
information at your
fingertips
Detach and mail today:
CLAGGK Inc.
P.O. Box 4099
Farmingdale, NY 11735
(Name)
(Street Address)
(City)
(State)
88
www.americanradiohistory.com
(Zip)
All Payment must be in U.S.
Funds!
THE CODE MAKERS
(Continued from page 64)
r
BUILD A WIRE TRACER
(Continued from page 46)
FUN WITH
ELECTRONICS
9 -volt battery, then
connect a clip
lead to the closed -loop output, J2,
and power up the circuit. Turn on a
small AM receiver and position it close
to the clip lead. Tune the radio until
you hear a buzzsaw -like sound, and
then adjust the tuning for maximum
signal strength. (The maximum transfer of energy occurs when the radio's
internal ferrite loop is positioned perpendicular to the wire).
Once that is done, connect the opposite end of the clip lead to the
common output, J3, and note the in-
The first Morse telegraph of 1835 didn't
use a key! Instead it used a "portrule,"
which was a wooden stick with a groove
designed to hold small lead blocks.
Before long, telegraphers were
adding hacksaw blades and additional contacts to make dots automatically when the handle was pulled
to the right. Horace Martin refined the
idea and patented the famous
Vibroplex. That semi -automatic key or
"bug" was the standard for highspeed telegraphy from the 1890's until
the end of World War II. They're still
popular, and in recent years old units
have become something of a collector's item. However, if you are not a
collector, and don't wish to pay col-
lector's item prices, the Vibroplex
Company is still very much in business.
The development of vacuum -tube
logic circuits in World War II made
electronic keyers practical. These key ers would make automatic dots or
dashes depending on which way the
lever was pushed and their speed
could be adjusted by a knob. The earliest models were crude but soon self completing dots and dashes, memories, iambic keying, and many other
features became commonplace. Today, many operators are using computers and keyboards to send Morse,
or a variety of other codes, with
speed, code type, and more selectable at the touch of a key.
Cod Dasipnard
Manual
El PC P113-THE PC MUSIC
111.
HANDBOOK .... $13.95.
Learn the basics of computer
music systems. For the professional musician, gifted amateur or just plain curious.
BP297- LOUDSPEAK-
crease in signal strength. The increase
in signal strength is due to circulating
current within the closed loop. (Anytime a closed loop can be used, the
signal will be greater and, in most
cases, easier to track.)
Now plug the McTrak into a 117 -volt
AC outlet and try to trace the McTrak
signal through the AC wiring using the
AM receiver. If the wiring happens to
go behind a metal panel in the wall or
is run through a metal conduit, the
metal will attenuate the signal, possibly making it too weak to follow. When
that happens (or if the signal is diminished for some other reason), try connecting the open -loop output (J1) to
the conduit and see if the signal can
be traced along the conduit.
Using McTrak to trace your auto's
electrical wiring is just as easy. With all
of the electronics in today's cars, ifs
almost impossible to visually trace a
wire from one location to another
without going through a maze of cables, and possibly becoming sidetracked. But McTrak can handle that
ERS FOR MUSICIANS ....
$6.25. Loudspeaker design
from the musician's point of
view! All you need to know.
and you should be able to design your own after reading
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ri
BP277 -HIGH POWER
AUDIO AMPLIFIER CON-
110.
STRUCTION ....$6.25. Here's
background and practical design information on high power
audio amplifiers capable of
300.400 watts r.m.s. You'll
find MOSFET and bipolar output transistors in inverting and
non -inverting circuits.
BP302 -A
CONCISE
USER'S GUIDE TO LOTUS
1 -2 -3 RELEASE 3.1 .... $6.25.
you am a PC user and want
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-A
BP298
CONCISE INTRODUCTION TO THE MACE
I
O.
INTOSH SYSTEM AND
FINDER .... $6.25. This introduction for those new to the
Mac. this book also serves as
a quick refresher for experienced owners that have not
used the machine in some
task as well.
trace your auto's wiring, connect
the McTrak's J2 output to the wire you
want to follow. Then track the signal by
moving the radio along the path that
produces the strongest signal. If the
receiver's signal is too weak, connect
the common lead (J3) to the car's
ground system (negative battery terminal or chassis in most vehicles) to
increase the signal strength. Since
there are some circuits in a car's electrical system that could be effected
by the full output of the Tracker, it
would be better to always use the
closed -loop output when working
with automotive electronics.
160 -COIL DESIGN 8
CONSTRUCTION MANUAL
.... $5.95. How to make RF, IF,
audio and power coils; chokes
and transformers. Practically
every possible type is discussed.
(I
Corqtr,retlm
time.
To
MAIL TO Electronic Technology Today, Inc.
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Massapequa Park, NY 11762 -0240
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89
CIRCUIT CIRCUS
(Continued from page
71)
oscillation to cease altogether.
TIME -DELAY CIRCUIT
over 25 p,F. Frequencies
greater than 50 kHz are
possible when using smaller
capacitor values for Cl.
Transistor Q3, configured
as an emitter-follower am-
plifier (which provides a
voltage gain of 1) is used to
buffer the output signal, so
that the circuit can be used
to drive a low- impedance
(under 1 megohm) load.
Only very high impedance
loads may be connected
directly to the sawtooth output at the UJT's emitter.
Almost any loading at Q2
will cause the output level
and frequency to drop, or
Our next entry, shown in
Fig. 5, places the UJT in a
time -delay circuit. With S1
and S2 in the normally
closed position, Q1's emitter
and Cl are tied to circuit
ground through the two
switches and R2, a 100 -ohm
resistor. Switching either S1
or S2 to an open condition
allows Cl to begin charging through R1 and R6. If
the switch remains open
longer than the RC time
period, Q1's emitter will
reach the trigger point and
fire. When that happens,
the positive output pulse at
B1 turns on the SCR and the
PARTS LIST FOR THE
TIME -DELAY CIRCUIT
RESISTORS
(All fixed resistors are 1/4-watt, 5% units.)
Ri -4700 -ohm
R2 -100 -ohm
R3-27 -ohm
R4-47 ohm
R5- 270 -ohm
R6- 1- megohm potentiometer
ADDITIONAL PARTS AND MATERIALS
Q1- 2N2646
-6
or unijunction transistor
SCR1
-amp, or less, silicon -controlled rectifier
25 -WVDC, electrolytic capacitor
C1- 25
C2- O.1 -µF, ceramic -disc
-4
S2-Normally closed sensor switch
Perfboard materials, enclosure, alarm sounder,
source, wire, solder, hardware, etc.
Si,
12 -volt power
PARTS LIST FOR THE
RF SNOOPER
SEMICONDUCTORS
Q1- 2N2222 general- purpose
NPN silicon transistor
Q2- 2N2646 or similar unijunction transistor
Q3-2N3904 general- purpose NPN silicon transistor
DI, D2-1N914 small -signal silicon diode
RESISTORS
(Al_ fixed resistors are 1/4-watt, 5% units.)
RI -2200 -ohm
R2- 330,000-ohm
R3 470 -ohm
R4 -3300 -ohm
R5-47 -ohm
R6-270-ohm
R7- 25,000-ohm potentiometer
Fig. 5. Here the UJT is used in a time -delay circuit. The time
delay afforded by this circuit can be varied from about one
second to over 30 seconds by adjusting R6.
-
R1
2.2K
047
Cat 0.047 -µF, ceramic -disc
C2, C3-0.01 -p.F, ceramic -disc
C5 0.22-PF, ceramic -disc
Wr
Dl
01
114914
JNN1
D2
Q1
#.".
ANTI-19 -inch or longer telescoping antenna
Perfboard materials, enclosure, knob, 9 -volt power source, wire,
solder, hardware, etc.
R7
25K
)1
C2
114914
2142222
C3
ADDITIONAL PARTS AND MATERIALS
SPKRI- Miniature 16-ohm speaker
R4
3 .3K
R2
330K
90
Cl,
+ 9V
ANTI
.01
CAPACITORS
R3
47052
C5
.22
C4
.047°
Fig. 6. In this handy little RF snooper, the UJT is configured as a
voltage-controlled oscillator. As the RF signal strength increases,
the output frequency of the voltage- controlled oscillator
increases.
alarm sounder is activated.
Even if the switch is returned
to its normally closed position, the alarm sounder will
remain activated until the
circuit's power is interrupted.
The time delay can be
varied from about one second to over 30 seconds by
adjusting R6. If a good
quality low- leakage 100 -µF,
electrolytic capacitor is sub-
www.americanradiohistory.com
stituted for Cl, the time
period can be increased to
well over one minute. The
alarm sounder may be replaced with a relay or
optoisolator /coupler to
control just about anything.
RF SNOOPER
A handy little RF snooper,
using the UJT as a voltagecontrolled oscillator (VCO),
is shown in Fig. 6. In that
circuit, an antenna (ANTI)
picks up RF signals. That
signal is coupled through
C1 to the base of Q1, which
is configured as an amplifier, Transistor Q1 amplifies
the RF signal, and the resulting output signal (at Q1's
collector) is fed to a two -
diode (D1 and D2) voltagedoubler circuit, which outputs a positive pulsating DC
output at the cathode of D1
that varies with the level of
detected RF
The DC output of the
doubler is fed to the UJTbased VCO. As the RF increases in strength, the
output frequency of the
VCO increases. The VCO
output is fed to Q3, which
amplifies the signal to a
level sufficient to drive
SPKR1. Potentiometer R7 allows you to adjust UJTbased VCO's frequency
range.
The antenna may be any
19 -inch or longer telescoping antenna. The snooper's
sensitivity may be increased
by increasing the value of
a good place to
experiment to obtain the
best overall circuit performance.
Here we are again at the
end of our monthly visit. So,
until we meet next time,
R6. That's
good circuitry.
portunity to experiment with
preceeding
analysis was based upon
my industry experience.
was impressed by the
simplicity, and usefulness of
Andy's circuit. became interested in electronics
myself at about his age.
hope Andy chooses to pursue electronics. It has been
a rewarding career for me
for the past 24 years.
ANTIQUE RADIO
(Continued from page 66)
THINK TANK
the tip. Those brown films
are quite common on early
radio equipment, and I've
always assumed that they
were grease or tar deposits
from household cooking or
be low enough to significantly load the telephone
line at the on -hook voltage
(48 volts). would start with
a 5- megohm potentiometer, adjust for the desired
results, then replace it with
a fixed resistor. (Note that
the saturation voltage of
Q2 is also affected by re-Charles Hardin, San
corder -motor load current.) Clemente, CA
What was the purpose for
Thank you for the excelresistor R4? It could be elim- lent analysis. While
inated, (shorted) and that
examining The circuit myself
might improve saturation of I forgot to double the juncQ2. A 100K resistor should
tion potential to get the
be connected across the
minimum saturation voltage
base -emitter junction of Q1. for the pair (oops).
That would shunt the small
That's all the room for
leakage current of D1 when now. If you have a circuit,
request, or comment you
the bridge output drops to
feel might earn you a "Think
5 volts, and shunt the reTank II" or other book,
verse leakage current of
the Q1 collector -base junc- please write to Think Tank,
Popular Electronics, 500 -B
tion. Cutoff would then be
Bi- County Blvd., Farmassured for Q1.
ingdale, NY 11735.
have not had the op-
smoking activities. When removing them, Alan points
out, one should always use
a wet process (rubbing with
steel wool dampened in
Brasso, as did, would
qualify) so as to trap the
dust. Dry sanding or rubbing processes should
I
definitely be avoided.
Reader Duane Buell
(Seattle, WA) responded to
my musings (September,
1992 issue) about the large
circular opening under the
Sky Buddy's main tuning
dial. That hole had been
punched, for no apparent
reason, then subsequently
filled, during the manufacture of the cabinet. Duane
theorizes that the cabinet
was manufactured for Hal licraffers by a metal
cabinet specialist such as
Bud or Par-Metal. The same
cabinet was sold, in slightly
different configurations, to
other radio manufacturers.
One of those required the
large hole; Hallicraffers
didn't.
If you have some Sky Buddy lore that you'd like to
share, be sure to write!.
Contact me do Antique
Radio, Popular Electronics,
500 -B Bi- County Blvd., Farmingdale, NY 11735.
this circuit. The
(Continued from page 74)
I
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91
NAVIGATION SYSTEMS
(Continued from page 42)
vice Center, police agencies, and
various agencies doing highway
maintenance and construction. TrayTek cars themselves provide data by
transmitting their speed and location,
which can be used to infer when and
where the vehicle encounters congestion or a traffic incident.
Travtek also offers an extensive information database of services and
attractions and on -line emergency
help with the ability to communicate
via cellular phone. These include service stations, hotels, motels, restaurants, and tourist attractions. The driver
is provided information in several formats. First, there are simplified maps
of the Orlando area graphically
showing routes plus traffic congestion
locations, incidents, and services information. A push of a button brings
up another format with information
about traffic incidents or available
services in text form. Another option
provides guidance instructions via
simple graphical cues such as directional arrows.
On the other side of the continent,
the Pathfinder demonstration program is already underway in Los Angeles. Pathfinder also uses an onboard navigation system that includes a CRT map display that presents traffic advisories and optimal
routes sent to it via radio. Alternatively,
information can be conveyed by synthesized voice messages over the car
radio's loudspeakers.
The on -board system interfaces
with the Los Angeles Traffic Management Center that includes the Los Angeles Traffic Management system.
Testing is being done on a 13 -mile
segment along the Santa Monica
Freeway, considered to be one of the
most heavily used roadways in the
92
country. The "Smart Corridor" used in
the demonstration not only includes
the freeway, but also freeway feeder
roads and five major arterial streets
that can be used as alternate routes
to the freeway. Besides sensors like existing induction loops embedded in
the roadway that measure traffic flow,
the Los Angeles TMS uses police accident reports and information on locations where maintenance is under way. Finally, sensors in Pathfinder-
equipped vehicles measure position,
heading, speed, and number of
stops, which is transmitted back by radio to the TMC. The California Department of Transportation (Caltrans), the
Federal Highway Administration
(P HA), and GM are jointly sponsoring
the Pathfinder Demonstration Project
using 25 specially equipped
Oldsmobiles.
An even larger NHS demonstration
project is planned for Chicago starting in 1993. Motorola navigation /route
guidance system could eventually be
installed in as many as 5,000 vehicles
in the Advanced Driver and Vehicle
Advisory Navigation ConcEpt (ADVANCE) program. These will be tied -in
with a Traffic Information Center via
RF
data -communication links. The Illinois
Department of Transportation,
Federal Highway Administration, and
the Illinois University's Transportation
Research Consortium are involved in
the project. The field- operation tests
will encompass a 200 -square -mile
area in the Northwest suburbs of Chicago. Incidentally, for about two decades the Illinois Department of
Transportation has operated a very
extensive and quite successful freeway- surveillance and control system
in the Chicago area. Traffic advisories
from this system are transmitted to individual drivers via updatable overhead and roadside signs, and reports
on cable iV and radio including low power roadside transmitters.
Over in Germany, the Siemens' Ali Scout was tested as part of the Guidance and Information System, Berlin,
or LISB for short in German. This is one
of many "Smart Cars and Smart Highway" projects in the very ambitious
Programme for European Traffic with
the Highest Efficiency and Unprecedented Safety (PROMETHEUS) project
that involves virtually every European
automaker, many suppliers, universities, and research institutes. LISB used
700 vehicles, 250 traffic lights, over
2,000 infrared beacons and covered
1500 kilometers (932 miles) of Berlin
streets. In the Ali -Scout system, data is
transmitted between cars and the
Central Computer via the IR link. The
degree of traffic congestion is inferred by comparing actual versus nominal travel times between beacons.
Information sent from cars is fused
with other data such as historical congestion profiles, whether schools are
www.americanradiohistory.com
weather conditions like fog
or ice, traffic accidents, construction
delays, and so forth. In the Ali -Scout
setup, the up-date map is contained
in session,
the central computer rather than in
individual cars. The Central Computer
continually calculates a minimum
trip -time route and transmits that information to the in-vehicle unit. If an Ali Scout equipped vehicle is on the path
to a traffic snarl, the Central Computer would guide the driver through another route that avoids this slowdown.
The Ali -Scout system also adjusts traffic -light timing to smooth overall flow
throughout the system. (We will be
looking at the Prometheus Project in
more depth in a future issue of Popular Electronics.)
The Japanese are also prototyping
major systems such as the Advanced
Mobile Traffic Information and Communication System ( AMTICS). Like
equivalent projects in the U.S. and Europe, AMTICS uses elements like onboard navigation systems, traffic management centers, congestion rerouting, and even telephone directories for services and such.
On -board navigation systems
could help all drivers, even those without vehicles so equipped. For example, Blaupunkt points out an imporin
tant fact about advanced driver information systems: Only a small percentage of the vehicles have to be
equipped with the systems to have a
noticeable effect. For example, if only
1% of all vehicles in a major metropolitan area were equipped with Ali Scout, overall traffic flow would be
noticeably smoother. A 10% installation would result in a major reduction
in congestion.
"OK, whose idea was it to hang Apples on
the Christmas tree ?"
MICROPROCESSORS
(Continued from page 62)
o
ANALOG
INPUTS
(8)
DATATO
SYSTEM
ANALOG
MULTIPLEXER
ANALOG
INPUT
ANALOG TO
DIGITAL
CONVERTER
DIGITAL
DATA
OUTPUT
LATCH
LATCH
READ
MULTIPLEXER
CHANNEL
SELECTION
CLEAR
COUNTER
ADDRESS
PROM
DATA
CLOCK
LATCH
"DATA
READY"
LATCH
t
o CLOCK/OSC
the devices on the external data bus.
The data buffer has three -state controls and data- direction controls that
are connected to the control -unit.
The low and high halves of the program- counter are registers that con-
tain the address of the current
instruction being processed. The control -unit increments the program counter registers and sends its contents to the address latches when the
next instruction is to be read or when
more information on the current instruction is needed.
The low and high halves of the
data- counter are registers that contain the address where data is located in external memory. They may
also be used as temporary registers.
The external control lines "Read, ,
'Write," "Memory," and "Input/Output"
come directly from the control -unit's
latches.
Next month, we'll look at some instruction examples and some special
instructions. That should show how all
these separate blocks function together to process instructions.
Fig. 4.
A simple controller could even run an analog -to- digital data- acqusition
system. That is because the task is limited to a series of steps that gets repeated over
and over.
Alnommlommwmommilk
**
ff
ANTENNA
POWER
ON/OFF
TRANSMITTER
MODULATION
POWER
ON /OFF
KEYER
CLEAR
COUNTER
ADDRESS
PROM
DATA
CLOCK
t
LATCH
LATCH
t
ó
NOT USED
o
CLOCK/OSC
MORSE CODE
MESSAGE
INPUT
sor's address bus. The address infor-
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Fig. 5. Since broadcasting a repeating message from a beacon transmitter is a
repetative task, a simple controller could operate such a transmitter. The PROM just
needs to be programed with the right sequence of steps to perform.
whether the result was a positive or
negative value, and /or if the result is
zero. The external status register provides these mathmatical results for
use by a program, while the internal
status register is used for the microprocessor's internal operations.
The outputs of the address latches
are connected to the microproces-
I
I
I
I
II
mation that is sent here is presented to
the ROM, the RAM, and the ports prior
to reading or writing data to these
devices.
The data buffer is a bidirectional,
non -inverting, three-state buffer that
connects the microprocessor's internal data bus to the external data bus.
That allows the microprocessor to
send data to and receive data from
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ADVERTISING INDEX
NOW Find the right Part
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CrQ,gs m
Vcig
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Free Information No.
President
5
$econd Edition
AMC Sales
29
Antique Radio Classified
96
CBC International
96
Christina Estrada
Assistant to the President
titgabers
15
Page
ADVERTISING SALES OFFICE
Gernsback Publications, Inc.
500 -B Bi- County Blvd.
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CLAGGK, Inc. Video Offer
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ISCET VCR
CROSS REFERENCE
This 272 -page reference contains
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Electronic Tech. Today
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Countersurveillance
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what was to be an embassy and private
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r
PE-1
CLAGGK INC.
P.O. Box 4099
Farmingdale, NY 11735
of the Counter*uncillancc'l'echniyucs
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hi rh
ou postage and handling
Please rush my copy
Video \
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The Dollars You Save
obtain the information contained in
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To
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drop on court decisions, bidding
Bill m(
information, financial data. The list is
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You know that the Russians secretly
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[.pire
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The professional discussions seen on
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The professional is not without his
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The professionals viewed on your television screen reveal information on the
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(
stair
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www.americanradiohistory.com
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