August 1962 Popular Electronics
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
Teenage amateur sleuths,
cum amateur radio operators, cum high-tech pranksters, cum serious electronics experimenters
Carl Anderson and Jerry Bishop save the day once again with a cleverly devised device
for erasing the contents of a tape recording. Their assignment, done at the behest
of a secretive government agent, might have been made easier if they had had access
to the super-strong rare earth
neodymium magnets of today since a stereo speaker magnet would
not do the job. Instead, the pair was forced to resort to a more challenging solution.
As is author Frye's style, in this 1962 issue of Popular Electronics
magazine he educates you on the workings of tape recorder erasing
circuitry and functionality in the process of telling the story.
Carl & Jerry: Electronic Eraser
By John T. Frye W9EGV
Carl, Jerry, Police Chief Morton, and a pale,
young, well-dressed stranger were engaged in serious conversation in the boys' basement
"I need rather specialized help in a hurry," young Mr. Adams was saying. "When
I talked to the department head ... of the Federal agency for which I work, I explained
the situation to him, and told him where I was, he remembered that you boys had
helped another of our operators about a year ago. He says you designed a small transmitter
that fitted inside a dog's collar and enabled our agent to get some valuable information."
Carl and Jerry explain the situation to police chief Morton.
"Sure; that was Mr. Cody, a big fellow who
was light on his feet and gave out next to nothing in the way of information," Carl
"Sounds like Cody," the pleasant stranger said with a wan smile. "Anyway, I was
told to contact you through Chief Morton and see what you could do. I'm afraid,
like Mr. Cody, I can only divulge just the information you must have to understand
the problem; but believe me, this affair is important to every living American.
"Tonight at ten a man will board a bus leaving here for Center City. He will
be carrying a small tape recording, probably in a briefcase. On the bus will be
another man waiting to receive the tape. After it changes hands, the receiver of
the tape will somehow check the recording to make sure it's what he wants. If he
is satisfied, a large sum of money will be given to the man who surrenders the tape.
"Now it's most essential, first, that the men do not know they are under surveillance;
second, that the tape not change hands; and third, if at all possible, that the
tape itself be destroyed. Can you men, with your background of electronics, think
of any way these three objectives might be accomplished ?"
"Am I right in believing it's the material recorded on the tape that you don't
want to change hands rather than the physical tape itself?" Jerry asked.
"That's right, but what are you driving at?"
"I was thinking of some method by which we might erase the tape without its ever
leaving the possession of the man who has it now."
"And without his knowing that it was being erased?"
"Yes," said Jerry. "I'm not at all sure it can be done, but suppose you give
Carl and me about three hours - until 8 p.m., say - to do some experimenting. In
the meantime, perhaps you'd better be thinking up a second plan to use in case we
"I like the way you think - " Mr. Adams started to say as he rose to his feet,
but suddenly he gasped and nearly doubled over in pain. "Guess I got kind of a catch
in my side," he explained as he straightened up. "I'll be back at eight to see what
you've found out, but I surely hope you come up with something. I don't seem to
be thinking too well today, and I ran out of ideas before I came here."
Sounds to me as though you're biting off quite a chunk, old buddy," Carl observed
after the other two had left.
"That business about the men not knowing any hanky-panky is going on while their
precious tape is being erased is the toughie. What do you have in mind? Rubbing
a big permanent magnet over the guy's briefcase?"
"It's worth trying," Jerry answered promptly. "Let's do some experimenting and
see what kind of results we can get with brute force d.c. erase - that's the name
applied to using a permanent magnet to erase a recording from a tape."
It didn't take the boys long to convince themselves that this approach showed
little promise. A very strong alnico magnet out of a speaker had to be almost in
contact with the tape to erase the recording completely. When a quarter-inch of
space was kept between the magnet and a recorded reel of tape, only a very slight
weakening of the recording was noticed.
"I was afraid of that," Jerry observed.
"We must be able to work through a distance of at least a quarter of an inch
to allow for the thickness of the leather in the man's briefcase, a cardboard container
for the tape, etc. You see, a d.c. erase system on a tape recorder doesn't consist
simply of a method of passing a tape over a strong permanent magnet. That's only
the first step, which leaves the tape in a very strongly magnetized condition. It
must then be passed over a weaker magnet of opposite polarity, or sometimes several
magnets of alternating polarity or a magnet with a diagonal gap in it, so that the
end result is a tape which is completely demagnetized. That's what we need, some
way of literally bathing the recording right through the briefcase with an alternating,
diminishing magnetic field."
battery-operated magnetic tape eraser.
"And how do we do that?"
"Let's try to construct a portable, battery-operated bulk eraser. As you know,
a bulk eraser is simply a strong electromagnet with 60-cycle a.c. going through
its coil. As a reel of tape is subjected to this strong reversing field and then
gradually withdrawn, the little magnetic particles of the tape are first jerked
violently in unison out of their recorded pattern and then are subjected to weaker
and weaker pushing and tugging forces that eventually leave them lying in the unpatterned
disarray of virgin tape."
"Don't you think it's going to be a little difficult to get a.c. out of your
batteries - or are you going to use a.c. batteries ?"
"Don't be cute. We can get a first cousin of a.c., pulsing d.c., simply by using
an interrupter between the batteries and our coil," Jerry retorted. "Suppose you
see what you can do about converting this old 6-volt auto radio vibrator into a
simple interrupter while I get started winding a magnet."
Jerry started by boring a small hole in the center of a 2"-diameter, 1"-thick
piece of soft iron; a bolt passed through this hole was able to hold two circles
of plywood clamped against the sides of the iron core. Next, he cut several short
pieces of plastic electrician's tape and looped them down into the space between
the two pieces of plywood with their sticky sides turned away from the wood and
iron. Then he chucked the end of the bolt in his electric drill and wound layer
after layer of #20 enameled wire on the core.
Jerry did his best to wind the wire in tight, even layers as the electric drill
rotated the core, and he kept at it until his bobbin of wire was some five or six
inches in diameter. Next, he carefully lapped the loose ends of each piece of
tape over each other to hold the wire securely in place while he removed the wooden
sides and pushed the iron core out of the middle. Now, very carefully, he wrapped
the whole doughnut of wire with thin plastic tape and then forced the soft iron
core back into the center.
By this time Carl had the vibrator reworked, and it was connected to a battery
eliminator and the coil so that the heavy contacts of the vibrating reed connected
and disconnected the six-volt d.c. supply to the coil at a rate of about 115 cycles
per second. A capacitor substitute box was connected across the points of the interrupter
and adjusted for minimum arcing; then a capacitor of this value was soldered in
Finally, the boys placed an issue of Popular Electronics on top of the coil,
laid a reel of recorded tape on top of that, and turned on the battery substitute.
The tape was slid around on the magazine for a few seconds and then lifted away
before the power was cut off. When the tape was placed on the recorder and run through
in the "Play" position, not a sound - except for a slight hiss - came from the recorder
"That does it!" Jerry exclaimed jubilantly. "Now let's get busy installing this
rat's nest and some parallel heavy-duty six-volt lantern batteries in that old
case of Dad's upstairs. We want plenty of current, for the magnetic field is dependent
on ampere-turns. Mr. Adams should be here in an hour, and I want to be able to give
him a convincing demonstration."
First they cut a hole in the side of the case so that one side of the coil could
be mounted flush with the surface of the leather. This opening was concealed with
brown press-on paper that was used to cover the entire case. The batteries were
anchored in place, and the vibrator was wrapped in several layers of sound-insulating
foam rubber. Wires were run through the handle to a simple push-button switch which
could be operated easily with one finger.
"We want to have our magnet just as close as possible to that reel of tape,"
Jerry said as he smoothed the thin paper over the magnet core. "The strength of
a magnetic field is inversely proportional to the distance, and it works on a square
law. Plus or minus a sixty-fourth of an inch might spell the difference between
success or failure in our completely erasing that tape."
He was interrupted by the arrival of Mr. Adams and Chief Morton. The former looked
even paler than he had that afternoon, and bent over a little.
Quickly the boys explained what they had done. They let Mr. Adams hear a few
feet of recorded tape and then placed the reel of tape in a briefcase. While Jerry
walked around the basement dangling this case from one arm, Carl brushed against
him with the attaché case. In spite of what seemed to be a very brief and casual
contact between the briefcase and the attaché case, the tape was found to be completely
blank when it was placed on the recorder.
"Guess we better show you how to work it; we haven't much time," Jerry offered.
"Boys, I have bad news for you," Mr. Adams said as he wiped cold sweat from his
forehead. "You're going to have to use that gadget yourself. The doctor is waiting
for me in a squad car outside, and I must go straight from here to the hospital
for an emergency appendectomy.
"This is a picture of the man who will have the tape," he went on. "You should
be able to spot him in the bus station. And here are two round-trip tickets for
the bus to Center City. Good luck!"
With that, Chief Morton half-led, half carried Mr. Adams through the door and
up the outside basement steps.
Meanwhile, Carl and Jerry stared at each other in pop-eyed amazement. "Well,"
Carl finally said, "I guess we better get started. You wrap up in your cloak while
I dash over and get my dagger!"
I Spite of their joking, both boys had a feeling of rising excitement as they
parked their car across the street from the bus station.
They spotted their man as soon as they entered the door, even though he was not
wearing dark glasses, had no beard, and looked amazingly like any ordinary businessman.
But he also happened to look exactly like the picture in Jerry's shirt pocket, and
a thin briefcase rested on his knees. Out of the corners of their eyes, the boys
could actually make out the square outline of the cardboard container for a 3" reel
of tape through the leather.
It seemed to Carl and Jerry the bus would never come, but finally it did. As
the stranger stood up with his briefcase in his right hand, Jerry transferred the
attaché case to his left hand and followed the man closely. At the door of the bus
there was a little knot of people awaiting the alighting passengers before they
started getting on, and it was here Jerry had his chance.
While Carl stood on the man's left and asked him something about whether the
bus was on time or not, Jerry pushed the switch under his finger and brushed his
case lightly against the briefcase, rubbing it around with a circular motion. The
man never noticed.
Perpetrators on the bus with their tape recorder.
The bus was not crowded. Carl and Jerry
followed their man to the rear, where he selected a seat alongside of a short fat
man who was dictating letters in a low voice into the microphone of a portable tape
recorder that was resting on his knees.
The two men apparently took no notice of each other until the bus was a dozen
miles out of town. Then the man with the briefcase turned to the other and said,
"Pardon me, sir, but I wonder if you might do me a great favor. I have a tape here
sent me by my nephew in the army overseas, but I have no recorder. Could you possibly
let me hear it on your machine ?"
"Why, certainly; just let me have it and I'll get it started for you," the fat
man answered obligingly.
As Carl and Jerry watched tensely, the fat man took the tape from the brief-case
and put it on the machine. Then he put the listening earpiece in his ear and started
the tape moving. After a few seconds he began to frown and he threw a switch that
sent the tape whirring at a faster speed. Next he turned the tape over and tried
to listen to the other side.
Finally he handed the earpiece to the first man and said coldly, "Your nephew
is a practical joker. There is absolutely nothing on that tape. Hear for yourself."
The man trying to sell the tape listened to every inch of it with growing puzzlement
and dejection. "I don't understand it; I don't understand it at all," he muttered
over and over.
"You'd better tell your nephew practical jokes can be dangerous," the little
fat man said menacingly as he turned his back and stared out the window.
At Center City Carl and Jerry followed their man outside the bus station. As
he walked past an alley, he impulsively tore the reel of tape from his pocket and
tossed it into an ash can. The boys retrieved it and took the next bus home.
Chief Morton was waiting for them at the station, and the three of them went
to the hospital. There Mr. Adams was out from under the anesthetic, and he was delighted
at what the boys told him.
"Well done!" he said weakly. "If this keeps up, we're going to have to put you
on our payroll. Seriously, though, you'll hear more about this as soon as I'm back
on my feet and send in my report. In the meantime, boys, you've done a great service
for your country - greater than you realize."
"As far as I can see, all we've done is get tangled up in some government tape,"
Carl said jokingly as they headed for the door.
Posted September 5, 2023
(updated from original
post on 4/10/2017)
Carl Anderson and Jerry Bishop were two teenage boys whose
love of electronics, Ham radio, and all things technical afforded them ample opportunities
to satisfy their own curiosities, assist law enforcement and neighbors with solving
problems, and impressing – and sometimes toying with - friends based on their proclivity
for serious undertakings as well as fun.
- See Full List -
Carl & Jerry, by John T. Frye
Carl and Jerry Frye were fictional characters in a series of short stories that
were published in Popular Electronics magazine from the late 1950s to the early
1970s. The stories were written by John T. Frye, who used the pseudonym "John T.
Carroll," and they followed the adventures of two teenage boys, Carl Anderson and
Jerry Bishop, who were interested in electronics and amateur radio.
In each story, Carl and Jerry would encounter a problem or challenge related
to electronics, and they would use their knowledge and ingenuity to solve it. The
stories were notable for their accurate descriptions of electronic circuits and
devices, and they were popular with both amateur radio enthusiasts and young people
interested in science and technology.
The Carl and Jerry stories were also notable for their emphasis on safety and
responsible behavior when working with electronics. Each story included a cautionary
note reminding readers to follow proper procedures and safety guidelines when handling
Although the Carl and Jerry stories were fictional, they were based on the experiences
of the author and his own sons, who were also interested in electronics and amateur
radio. The stories continue to be popular among amateur radio enthusiasts and electronics
hobbyists, and they are considered an important part of the history of electronics
and technology education.
Educated Nursing - April 1964
- Going Up
- March 1955
Shock - September 1955
- A Low Blow
- March 1961
- The Black
Beast - May 1960
Electronik, September 1958
- Pi in
the Sky and Big Twist, February 1964
Bell Bull Session, December 1961
Boogie, August 1958
- TV Picture,
Eraser, August 1962
Trap, March 1956
at Work, June 1956
Aweigh, July 1956
Has His Day, August 1956
- The Hand
of Selene, November 1960
or Not?, October 1956
Electronic Beach Buggy, September 1956
Extra Sensory Perception, December 1956
in a Chimney, January 1956
Performance, November 1958
of Judas, July 1961
- The Sucker,
New Year, January 1963
Snow Machine, December 1960
Extracurricular Education, July 1963
Slow Motion for Quick Action, April 1963
Sleuthing, August 1963
- TV Antennas,
a Soroban, March 1963
Fair --", September 1963
Worm Warming, May 1961
The Electronic Bloodhound - November 1964
Great Bank Robbery or "Heroes All" - October 1955
Operation Startled Starling - January 1955
- A Light
Subject - November 1954
Teaches Boy - February 1959
- Too Lucky
- August 1961
and Jeopardy - December 1963
Santa's Little Helpers - December 1955
Tough Customers - June 1960
Pocket Radio, TV Receivers
Yagi Antennas, May 1955
Stomping, March 1962
- The Blubber
Banisher, July 1959
- The Sparkling
Light, May 1962
Research Rewarded, June 1962
- A Hot Idea, March
- The Hot Dog
Case, December 1954
New Company is Launched, October 1956
the Mistletoe, December 1958
Eraser, August 1962
- "BBI", May 1959
Sound Waves, July 1955
- The River
Sniffer, July 1962
- Ham Radio,
Torero Electronico, April 1960
Wireless, January 1962
Electronic Shadow, September 1957
Induction, June 1963
- He Went
Detective, February 1958
an Instinct, December 1962
- Two Detectors,
with a Tachometer, July 1960
and the Pirates, April 1961
The Crazy Clock Caper, October 1960
Carl & Jerry: Their Complete Adventures is
now available. "From 1954 through 1964, Popular Electronics published 119 adventures
of Carl Anderson and Jerry Bishop, two teen boys with a passion for electronics
and a knack for getting into and out of trouble with haywire lash-ups built in Jerry's
basement. Better still, the boys explained how it all worked, and in doing so, launched
countless young people into careers in science and technology. Now, for the first
time ever, the full run of Carl and Jerry yarns by John T. Frye are available again,
in five authorized anthologies that include the full text and all illustrations."