February 1958 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.
Long before their
college days at Parvoo U., our two amateur electronics sleuthing buddies were
on the job tracking down and trapping bad guys by using their combined knowledge
of circuits and physics. In this episode, Carl and Jerry are tasked with helping
a hobby store owner stop a rash of thefts that always seems to occur during
a busy time right after school lets out for the day. Their first inclination
was to devise a system like the big department stores were installing that used
passive tags on items that would trigger an indicator when passed through the
detector at the exit door. That was in 1958 (the year I was born, yikes!) when
the anti-theft tags were first being utilized. Unfortunately, the system they
were able to build was not sensitive or selective enough, so they came up with
a different scheme that helped the storekeeper nab the perp. It was quite elementary,
as a world-famous detective was fond of saying.
Carl & Jerry: Electronic Detective
By John T. Frye
A February snowstorm was swirling around outside as Carl Anderson came stamping
into the basement laboratory of his friend, Jerry Bishop. His horn-rimmed glasses
instantly steamed over in the warm room, and when he took them off he saw that
Jerry had company. A pleasant-featured young man was sitting on the worn leather
sofa watching Jerry doing something at his workbench.
"Hi, Carl; this is Mr. Singer who owns that hobby shop at Fifth and High,"
Jerry announced. "He's got a problem."
"Glad to know you, Carl," Mr. Singer said, as he stood up and shook hands.
"I've got a problem all right. Shoplifters have really started working me over.
As you know, our merchandise is mostly on open display so that the youngsters
who make up a large part of our trade can handle it. That makes it easy picking
for anyone so inclined. Naturally we expect some losses of this nature, but
recently they've become serious."
"What sort of things are snitched?"
"Everything from a bicycle on down!
However, that fancy cap pistol Jerry has over there on the bench seems to
be a favorite. We've lost a couple of dozen of those since school started."
Everything was built on a flat sheet of Bakelite that fitted
easily beneath the cardboard shelf to which the pistol was securely fastened.
"Then it must be children doing it." "That's right; and that's what makes
catching the sticky-fingered person such a ticklish proposition. Maybe I'm a
softy, but I don't want to call the police in on this and maybe send some kid
to reform school. I just want to find out who's doing it and put a stop to it.
I feel I have to show the kid doing it that no-one gets away with what he's
pulling for long; otherwise he may develop into a real criminal."
"Don't you keep an eye on things?"
"We try, but you can't appreciate what a job it is until you see the after-school
crowd that jams into our store. We have all we can do waiting on trade, stopping
scuffling, etc., without trying to watch all the counters and aisle displays
at once. And the thief is pretty crafty. We thought we could stop the loss of
the pistols by wiring them in their boxes; but they kept right on disappearing,
box and all!"
"Carl, you're just in time to help me try something," Jerry interrupted.
"I read the other day that some big department store had installed an electronic
shoplifting detecting device that was triggered whenever a special price tag,
actually a miniature printed tuned circuit, was brought near it. Price tags
were removed from all merchandise when sold; so if anyone tried to carry something
off without buying it, the electronic gadget would squeal on him.
"I figure the detecting device must be simply a glorified grid dip oscillator
such as the one I have here on the bench. As Carl knows but possibly you don't,
Mr. Singer, a 'GDO,' as we call it, is simply a vacuum-tube oscillator with
a meter that reads the rectified grid current which flows from the tube grid
to ground as long as the tube is oscillating. The amount of grid current is
proportional to the vigor of oscillation. Whenever another circuit tuned to
the frequency at which the GDO is oscillating is brought near the coil of the
oscillator, this tuned circuit absorbs energy from the oscillator by induction.
This cuts down on the vigor of oscillation and produces a reduction or 'dip'
in the current reading of the meter."
"I see that this loop of wire strung around the door frame is replacing the
coil ordinarily plugged into the GDO," Carl observed.
"That's right. And this little coil-and-capacitor combination is tuned to
the frequency at which the grid dip oscillator is working. I want you to walk
back and forth through the door without it first - then again with it in your
As Carl made the last trip, Mr. Singer walked over and watched the meter.
"The pointer moved!" he exclaimed.
"Yes, but not enough I'm afraid," Jerry said. "I was hoping we'd get a really
strong kick that would operate a sensitive relay. And there was a current change
caused by body capacity effect when Carl went through the loop without the tuned
circuit. Probably we could get away from that by housing the loop of wire in
some sort of Faraday shield which would stop capacity effects without interfering
with magnetic induction ... and we could amplify the grid current change with
a d.c. amplifier until it would kick a relay. But I'm afraid all that wouldn't
be practical for just this one job."
"Well, I'm sorry you can't help, but I certainly appreciate your trying,"
Mr. Singer with obvious disappointment as he began buttoning his overcoat.
"Wait a minute!" Jerry exclaimed. "We don't give up that easily. I've got
another idea that should be sure-fire."
"Let's hear it," Mr. Singer said, sitting down again.
"Well, I've been looking at this cap pistol carton, and I see there's plenty
of room beneath the cardboard insert that holds the pistol for us to conceal
a transistorized, tone-modulated transmitter. This will have a range of only
about 50 feet; so if the pistol is placed on a counter at the rear of your store,
the signal won't be heard on the receiver we'll place near the front door -
with an antenna lead from the receiver fastened around the door frame. However,
if anyone tries to carry the pistol and transmitter through the door, the signal
from the transmitter will be heard very loudly in the receiver."
"Sure it will work?" Mr. Singer quizzed. "Sure I'm sure," Jerry said confidently.
"Carl and I have played around with these transistorized wireless mike circuits
a lot, and we know how to build them and what they will do. Suppose you don't
display the cap pistols for a couple of days while Carl and I build up the transmitter
and check it out. Then you can put this special one on display, and the kid
pinching them will probably snap it right up."
"That's exactly what I'll do," Mr. Singer agreed. "Just let me know when
The door had hardly closed behind him before Carl and Jerry were busy laying
out the little transmitter. There was no problem with the circuit, for all they
had to do was combine a transistorized "wireless mike" transmitter and a simple
transistorized audio oscillator. The audio oscillator replaced the microphone
of the transmitter and modulated the output with a steady tone of about 500
cycles per second. The transmitter was set to work on an unused area near the
low end of the broadcast band so that an ordinary radio could be used to pick
up the signal. Everything was built on a flat sheet of Bakelite that fitted
easily beneath the cardboard shelf to which the pistol was securely fastened.
When the equipment was working to their satisfaction, the boys contacted
Mr. Singer; and that evening the three of them went down to the store and set
up "Elmer, the Electronic Flatfoot," as Carl insisted on calling it. Everything
worked exactly as Jerry had predicted. It was agreed the boys would rush right
to the store from school the next day and that Mr. Singer would not put out
the pistol until they arrived.
Removing the receiver from his shirt pocket, he used it
as a search wand to go over each one.
It seemed as though school would never let out the next afternoon, but when
it finally did Carl and Jerry really hot-rodded their bikes down to the store.
Mr. Singer was waiting for them. Jerry switched on the hidden transmitter, and
the "bait" was provocatively displayed.
Almost immediately the store began to fill with a crowd of shouting, shoving,
noisy boys. Jerry and Carl stayed near the front of the store and deliberately
avoided even looking at the counter holding the cap pistol. Mr. Singer, his
wife, and two clerks were busy waiting on customers.
A good half hour passed without anything happening. The boys were just beginning
to think that no one was going to try to make off with the pistol when they
heard a weak musical tone in the receiver. Steadily it increased in strength.
Mr. Singer heard it and came over to stand by Carl and Jerry. As two well-dressed
boys carrying school books went through the door, the tone reached a very loud
level and then began to subside.
Mr. Singer called after them: "Say, fellows, come back here a minute. I want
to talk to you."
The two schoolboys exchanged a long look and then slowly came back to the
store. As they crossed the threshold, the receiver once more built up to a peak
"Come on back to my office," Mr. Singer said.
They walked back with him, tossing their books on an empty counter as they
went past. Carl and Jerry followed, and for the first time Carl noticed that
Jerry was wearing his little shirt-pocket transistor receiver with its earphone
tucked in his ear. Carl also noticed that as Jerry walked along just behind
the two boys he kept fumbling with the tuning control of this receiver, and
his face had begun to wear a puzzled, worried look.
"I was going to use this to tell which one had it," he whispered to Carl,
"but I can't pick up the signal near either of them!"
"Maybe the transmitter's gone dead," Carl suggested.
"Nope, I can still hear it faintly on that receiver up front," Jerry observed
as they reached the door of Mr. Singer's office. "You tell Mr. Singer to stall,"
he said desperately, "while I see if I can find what's gone wrong."
As the rest of them filed into the office, Jerry turned around and started
walking slowly toward the front of the store, tuning his little receiver back
and forth across the low end of the broadcast band as he did so. Suddenly he
began picking up the tone signal, but after he had walked about two-thirds the
length of the store it began to fade out again. Backtracking, he found that
the signal reached a peak when he was standing by the books the boys had tossed
on the counter. He quickly spread the books out on the counter. Removing the
receiver from his shirt pocket, he used it as a search wand to go over each
of them. One large, fat volume on ancient history gave out a very loud signal.
Jerry opened the book and made an astonishing discovery. The first and last
few pages of the book were intact, but the center of all the middle pages had
been cut out. Inside this opening was the cap pistol still wired in its box.
He picked up the book and, holding it behind him, stepped into the office.
"Which one of you boys is named William Palmer?" Jerry demanded.
The boy with dark auburn hair and freckles spoke up hesitantly: "That's me."
"Then this must be your book with your name in the front of it," Jerry said
quietly as he placed the book on the desk in front of Mr. Singer and opened
The Palmer boy's face turned so deathly white that his freckles seemed to
stand out in three-dimensional style.
"I didn't really mean to steal," he stammered. "Honest, I didn't. It just
seemed a kind of game, and the other fellows kept egging me on. Are - are you
going to send me to jail?"
"Come on, Carl," Jerry said as he headed for the door.
Carl followed, but even after the door was closed behind them Carl and Jerry
could still see the pale frightened faces of the two boys and the stern serious
look on the face of Mr. Singer.
"What do you suppose Mr. Singer will do with them?" Carl wondered.
"I'm not sure, but it will be what's best for the boys," Jerry declared with
conviction. "They just don't know how lucky they are that they were caught by
a fine man like Mr. Singer. You can bet he'll not let them off too easy. From
the looks on their faces, though, I think they've already learned their lesson."
"But they'll never know it was Elmer, the Electronic Flatfoot, who put the
arm on them!" Carl said with a grin.
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.
- Carl &
Jerry: 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
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."
Posted July 17, 2020
(updated from original post on 9/17/2014)