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Carl & Jerry: Electronic Trap
March 1956 Popular Electronics

March 1956 Popular Electronics

March 1956 Popular Electronics Cover - RF CafeTable of Contents

Wax nostalgic about and learn from the history of early electronics. See articles from Popular Electronics, published October 1954 - April 1985. All copyrights are hereby acknowledged.

Jerry missed an opportunity to patent his capacitive touch switch, the sort used to control everything from living room lamps to kitchen sink faucets. Untold millions of dollars in royalties could have paid for his engineering degree at Parvoo University and then used the rest as seed money for a startup business. When I started reading the adventure of Carl & Jerry, I thought they were going to rig the metal door to issue a high voltage pulse to whatever touched it, but that probably would have been too much of a liability for Popular Electronics to risk since readers would sometimes replicate the devices described in the articles.

Carl & Jerry: Electronic Trap

By John T. Frye

Carl & Jerry: Electronic Trap, March 1956 Popular Electronics - RF Cafe

... It must have been around two o'clock in the morning when Jerry was awakened by the light that winked on and off a few times in his face and then shone steadily.

"What are you doing?" Carl demanded lazily, as he turned over on his side on the leather couch to, watch his chum, Jerry, who was busily twisting .the knobs of a small box sitting on the basement laboratory workbench.

"Deciding whether to take French or Spanish next year," Jerry answered curtly, as he continued to adjust the dials.

Carl heaved his lanky frame erect and strode over to the bench.

"It sounded just as if you said you were deciding whether to take French or Spanish next year," he said laughingly, and peered curiously through his horn-rimmed glasses at the little cabinet studded with knobs, switches and a small meter.

"That's what I did say."

"Then you've flipped your wig for sure. I suppose you just say: 'Black box, black box, on the bench,

Which shall I take: Spanish or French?' and then this electronic understudy for the Delphic oracle mulls it over for a few micro-seconds and comes up with the right answer."

"That's not too far off," Jerry said, with a grin on his round face. "This thing is the 'Decision Meter' described back in October, 1955, Popular Electronics. You can read the article for yourself, but briefly the gadget works like this: when these five dials, which operate potentiometers, are all set at zero, zero voltage appears across this meter. Turning a knob in a counterclockwise direction applies an increasing negative voltage to one terminal of the meter; turning the knob in the opposite direction applies an increasing positive voltage. I arbitrarily assigned negative values to arguments for French and positive values to arguments in favor of Spanish. As each point came to me, I turned one of the knobs to right or left in accordance with whether Spanish or French was favored by that particular consideration. How far I turned the knob depended upon how important the consideration was. Finally, when all the arguments had been recorded, the instrument automatically and electrically summed up the influence of all the knob settings, and showed by the way the meter was deflected whether Spanish or French was favored. As you can see for yourself, for me personally, Spanish was indicated the better choice."

"Well blow my fuse!" Carl exclaimed.

"Imagine us having an electronic brain!"

"That's what it really is, in a modest sort of way. Say, Carl, I want to show you something," Jerry said suddenly, and he went over and opened the cellar door leading to the outside. "See these bad scratches on the outside of the door? Pop is pretty steamed about them. He thinks Bosco is doing it, and he says - and I quote - 'Either Carl's got to put boxing gloves on that mutt or give him a close manicure before we have the house repainted this spring' - unquote."

"Bosco wouldn't do a thing like that," Carl denied hotly, getting down on his knees to examine the scratches closely. "In the first place, he's too lazy to scratch that hard."

"Well, I'm neutral, but I have an idea how we can find out what's doing it."

As he finished speaking, Jerry dived into the large junk box beneath the bench and came up with a small dusty chassis bearing two tubes, a couple of knobs, and a relay.

"What's that nasty-looking thing?" Carl asked suspiciously. "I'm not going to have Bosco hurt."

"Don't worry. I'm as fond of that animated flea-garage as you are. This is a capacity relay that will let me know when anything gets close to that door during the night. I built it according to an article that appeared in the very first Popular Electronics back in October, 1954."

"How does it work?"

"A sensing wire fastens to this binding post which is connected to the grid of the triode section of the 12SQ7 tube. This triode section is hooked up as an r.f. oscillator. Some of the r.f. voltage produced by the oscillator is rectified by the diodes of the 12SQ7, and this d.c. voltage is applied as negative grid bias to the 50L6 tube - which has a sensitive relay in its plate circuit. As long as the oscillator is operating strongly, a high bias is produced and the plate current of the 50L6 is low, allowing the relay to stay open. However, if any living thing or large metallic object approaches the sensing wire, the capacity between that object and the wire provides a path through which some of the oscillator energy is drained off. As the oscillation weakens, so does the negative voltage produced by the rectifying diodes. This decreasing negative bias causes the 50L6 plate current through the relay to climb, closing the relay. The closing contacts can turn on a light, ring a bell, or operate any other electrical device."

While talking, Jerry had been installing a short sensing wire along the door jamb and connecting a light bulb, so that it could be turned on and off by the relay contacts. After carefully adjusting the sensitivity controls of the capacity relay, he could cause the light bulb to turn on simply by walking within three or four feet of the door. When he stepped back again, the light would go out.

"Now I'll feed this light current through the relay contacts into the pair of wires I have going up to my bedroom," Jerry explained; "and whenever anyone or anything comes close to this door, it will automatically turn on the light up there. That will wake me, without disturbing anyone else, and I can sneak down here and discover Old Scratch - whatever he is-right in the act."

"It sounds just goofy enough to work," was Carl's comment as he started for home. He could not resist waltzing back and forth across the threshold a couple of times to make the light blink on and off before he started climbing the steps that led up to the yard level.

Quietly, he slipped into his bathrobe and soft-soled slippers, and started for the basement laboratory. When he reached the door that led from the furnace room into the laboratory, he stopped short at the sound coming from the outside laboratory door. It was not a scratching sound. Instead, it sounded more as though some heavy metallic object was being run up and down the edge of the door.

"I always knew old Bosco was plenty smart, but I never thought he knew how to use a crowbar," Jerry marveled to himself.

At that instant there was a sort of crunching sound, and the door swung open. Jerry waited only long enough to see the tall outline of a man step inside and start probing the workbench with the narrow beam of a flashlight held in his hand; then the boy fled silently up the stairs behind him. When he reached the kitchen at the top of the stairs, he debated briefly as to whether or not he should go on upstairs and try to wake up his father; but as he recalled how hard that worthy was to awaken, and how panicky his mother was likely to become, he quickly decided against this. He moved silently into the den and lifted the telephone receiver from the cradle. Silently he gave thanks to his scoutmaster for making every boy in the troop memorize the numbers of the fire department, the police department, and a twenty-four hour ambulance service. Using only his sense of touch, he fumblingly dialed the number of the police department. Although the dial mechanism was really very quiet, its whirring sounded like the grinding of a concrete mixer to the frightened boy - in fact, it made almost as much noise as his pounding heart.

"Police department, Sergeant Anderson speaking," a drawling voice came from the receiver.

"This is Jerry Bishop at 1810 Spear Street.

A burglar just broke into our outside basement door on the west side of the house and is prowling around here somewhere right now. Come quick," Jerry whispered hoarsely into the mouthpiece that he was wearing almost like an oxygen mask.

The voice that answered was crisp and businesslike, with all the drawl gone from it: "I gotcha, kid. Don't get in his way. Just lay low. Our squad car will be there in a few seconds. Don't try to answer. He may hear you. Just hang up and make yourself scarce until we get there."

Jerry tried to replace the receiver softly in the cradle, but at the moment of contact it chattered against the base with a rattle like that of castanets. Holding his breath, Jerry stood there in the dark listening intently. For a few long seconds he heard nothing except the pounding of his heart; then, very softly, there was a familiar creak of the basement stairs. The burglar was coming up to the first floor. Peering through a crack in the door of the den, Jerry could see a suffused glow of light on the kitchen ceiling.

For the next few minutes - which seemed like hours - the boy used his knowledge of the house to keep out of the way of the prowler, who quietly but systematically went about ransacking the whole downstairs. Whenever he found something to his fancy, he chucked it into a burlap sack he carried over his shoulder in true comic-book-burglar fashion. Since he moved very slowly and deliberately, it was not hard for Jerry to keep him in view, without being seen himself. At one time the boy thought he heard the sound of a distant car motor, but he could not be sure. He was concentrating so hard on keeping out of the way of that probing flashlight beam that he had scant time to notice anything else.

Suddenly, as the man stood at the bottom of the stairs, a light was turned on in Jerry's room at the head of the stairs. It flickered on and off a couple of times and then went out; but at the first flicker the burglar had switched off his flashlight and moved swiftly toward the kitchen and the stairs leading down into the basement. Jerry, confident that the flickering light from his bedroom had been caused by the police coming through the outside door of the basement, followed warily. Just as he reached the head of the basement stairs, the furnace room below was flooded with light and two policemen with drawn revolvers faced the burglar standing in the middle of the floor.

"Don't move," the tall, lanky policeman commanded. His short, stout partner moved forward and placed a pair of handcuffs on the wrists of the burglar, whose mouth still gaped open with surprise.

"Boy, am I glad to see you guys!" Jerry exclaimed, thumping down the cellar steps. "Those brass buttons on your uniforms look prettier to me right now than any Christmas tree ornament I ever saw!"

"Now there's a heartfelt testimonial," the tall policeman chuckled; "but while the compliments are going around, you've got some coming for keeping cool and using your head. How did you happen to - "

He broke off sharply as strange sounds issued from the adjoining laboratory. There was a scratching at the outside door accompanied by a faint clicking that Jerry recognized as coming from the relay in the capacity-operated unit.  

"Sh-h-h! Maybe it's an accomplice," the lanky policeman said, as he moved swiftly across the laboratory to the door and stood poised before it with his revolver tightly clenched in his fist. He jerked the door open and sprang to one side all in a single motion. There in the doorway - with one paw still raised to scratch the disappearing door - stood Bosco, a look of doglike astonishment in his brown eyes. Then he recognized Jerry, and his stubby tail began to vibrate at about sixty cycles per second.

"Come on in, you old rascal," Jerry ordered; then he dropped on his knees and hugged the shaggy dog with almost hysterical affection. "You got caught in the trap, all right, but when Dad hears that because of you we caught a burglar, maybe he won't worry too much about a few little scratches on the cellar door!"

 

 

Posted February 15, 2017


Carl & Jerry: Their Complete Adventures - RF Cafe Featured BookCarl & 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 lashups 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."

Carl & Jerry Episodes on RF Cafe

- Electronic Eraser, August 1962

- Electronic Trap, March 1956

- Geniuses at Work, June 1956

- Eeeeelectricity!, November 1956

- Anchors Aweigh, July 1956

- Bosco Has His Day, August 1956

- The Hand of Selene, November 1960

- Feedback, May 1956

- Abetting or Not?, October 1956

- Electronic Beach Buggy, September 1956

- Extra Sensory Perception, December 1956

- Trapped in a Chimney, January 1956

- Command Performance, November 1958

- Extracurricular Education, July 1963

- Treachery of Judas, July 1961

- The Sucker, May 1963

- Stereotaped New Year, January 1963

- The Snow Machine, December 1960

- Extracurricular Education, July 1963

- Slow Motion for Quick Action, April 1963

- Sonar Sleuthing, August 1963

- TV Antennas, August 1955

- Succoring a Soroban, March 1963

- "All's Fair --", September 1963

- Operation Worm Warming, May 1961

- The Blubber Banisher, July 1959

- The Sparkling Light, May 1962

- Pure Research Rewarded, June 1962

- A Hot Idea, March 1960

- The Hot Dog Case, December 1954

- A New Company is Launched, October 1956

- Under the Mistletoe, December 1958

- Electronic Eraser, August 1962

- "BBI", May 1959

- Ultrasonic Sound Waves, July 1955

- The River Sniffer, July 1962

- Ham Radio, April 1955

- El Torero Electronico, April 1960

- Wired Wireless, January 1962

- Electronic Shadow, September 1957

- Elementary Induction, June 1963

- He Went That-a-Way, March1959

- Electronic Detective, February 1958

- Aiding an Instinct, December 1962

- Two Detectors, February 1955

- Tussle with a Tachometer, July 1960

- Therry and the Pirates, April 1961

- The Crazy Clock Caper, October 1960

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