April 1963 Popular Electronics
of Contents] People old and young enjoy waxing nostalgic about
and learning some of the history of early electronics. Popular Electronics
was published from October 1954 through April 1985. All copyrights are hereby
acknowledged. See all articles from
Our two intrepid techno-sleuths are in college by now, but that does not keep them from applying
their well-honed mystery solving skills to hometown situations while on spring break. The boys
invoke the scientific method of
Mr. R.R. Dibble, a New Zealand scientist, to help prove to county commissioners that a certain
part of their critical infrastructure was in need of repair. An nth-generation farmer's observation
was not proof enough, so indisputable empirical data would be needed. Real-life inventors and
company's unique instruments are often incorporated into the Carl & Jerry series that ran
for many years in Popular Electronics.
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Carl & Jerry: Slow Motion for Quick Action
By John T. Frye W9EGV
and Jerry, home from college on spring vacation, had spent the beautiful warm afternoon wandering
along the banks of Wildcat Creek with their transistorized tape recorder gathering a collection
of spring sounds. Already stored on the little reel of tape were the gay "churlik! churlik!" of
a robin, the excited cawing of a surprised crow, the "barrrump! barrrump !" of a bullfrog, the
scolding trill of a piney squirrel, and the sounds the flooding creek made as it poured over rocks
and sucked at the swollen buds on the willow branches dipping into its muddy waters.
Now the youths were sitting cross-legged on the floor of a rustic wooden covered bridge that
spanned the creek and staring curiously up at the great hewed timbers constituting the framework
of the structure. They did not have to worry about traffic through the bridge. A bad washout in
the winding road leading to it had taken care of that for several days to come.
"They had some darned good engineers away back when this bridge was built," Carl offered. "It's
at least seventy-five years old; yet those timbers look perfectly sound."
"That was partly the reason for the roof," Jerry explained. "It protected the weight-bearing
timbers from the weather. The covered bridge also provided the traveler with shelter from a sudden
"Yeah, and what a dan-dan-dandy place to rest the horse and pitch a little woo!" Carl added
with a grin. "Hey!"
he exclaimed, "am I imagining it, or did this thing shake a little?"
"Most likely it did," a voice answered from the end of the bridge. Silhouetted against the
light was the lanky frame of an elderly farmer.
"I'm Clyde Butcher," he introduced himself. "I own that farm over there in the bend of the
creek that has the old grist mill on it. It was my daddy's before me and his daddy's before that.
"This old bridge needs care bad," he explained, "but we can't convince the county commissioners
of it. Their smart-aleck young engineer knows nothing about wooden bridges, and he just laughs
when we try to tell him the bridge
doesn't sound right and it doesn't feel right."
"I'm not sure I understand," Jerry said politely.
know that a crack in a violin will show up in the sound long before you can see it through the
varnish, and a tight-rope walker can tell by the feel of the rope when something is wrong with
the rigging," the old man said earnestly. "Well, just remember that I and many like me have been
passing over this bridge all our lives. We know the normal sound it has when a wagon rolls across
this floor, and we know it used to have a little bounce to it even when a heavy dog trotted across
it. Now it doesn't sound right, and the bounce has gone out of it. The floor is sagging, too,
as you can see; but that snooty engineer says it has always sagged. That's a lie. He'd like to
tear the whole thing down and put in a new concrete bridge."
"That would be barbaric!" Carl exclaimed. "Only a few of these fine old bridges are left in
the whole state."
"I'm glad to meet young men with a little respect for something old," Mr. Butcher said as he
shook hands with the boys. "This old bridge is settling a fraction of an inch or so every day,
especially during this period when the frost is going out of the ground; and unless she's given
some help, she won't be here much longer."
"If you just had some evidence of this settling you could present directly to the commissioners,"
Jerry said thoughtfully as he stared down at the tape recorder in his lap, "maybe they'd do something."
"Maybe," the old farmer said doubtfully; "but it would have to be something simple and convincing.
They know as much about engineering as a hog knows about Sunday - even less than I do."
"Could you run an a.c. line from your barn over here to the bridge to power electronic equipment
we would install to record the settling of the bridge?" Jerry asked.
"Sure, but the bridge only settles a freckle every few hours. Those commissioners aren't going
to sit still listening to several hours of recording."
"They won't have to. I was reading the other day that
RR Dibble, a scientist at the Department of Scientific and Industrial Research at Wellington,
New Zealand, had modified a household tape recorder to operate 500 times slower than normal and
used it to record 'ice quakes' at Antarctica. The tape only moves about a half-inch a minute;
so an 1800-foot reel of tape will last a month of continuous operation. When the tape is played
back at normal speed, the very slow vibrations of a quake become audible sounds. What's more,
twenty-four hours of recording can be reviewed in slightly less than three minutes."
"You lost me," the old gentleman confessed; "but if you think it will work I'm game to try
it. I'll string that wire first thing in the morning."
It didn't take the boys long to drive to their laboratory in the basement of Jerry's house.
Once there, they immediately set to work revamping an old discarded tape recorder they had been
hoarding against just such an emergency.
"You slow down the recorder, and I'll make up a special bridge-settling transducer and an ultra
low-frequency amplifier," Jerry suggested. "I think you can substitute that powerful little 4-rpm
synchronous motor for the one in the recorder to get pretty close to that 1/500 speed reduction,
and then you can turn down the capstan to hit it right on the nose. Brother Dibble probably didn't
do it that way, but it's the quick-and-dirty method we'll use."
"Aye, aye, sir!" Carl said mockingly, starting to remove the tape recorder motor; "but how
are you going to make a bridge-settling transducer?"
could use a sensitive accelerometer if we had one - which we don't," Jerry mused, "and no ordinary
mike will work because we're not trying to detect audible frequency vibrations. We need something
that will translate a single slight vertical movement into an audible sound .. What do you think
of this? We'll mount a crystal phono cartridge on its side. A length of springy piano wire will
be inserted in the needle chuck, and a small weight will be put on the end of the wire. The length
of the wire and the amount of the weight will be such that when it's disturbed it will vibrate
back and forth at a slow rate, say a couple of cycles per second. The flexing of the crystal caused
by this motion will produce a low-frequency alternating voltage that can be amplified and recorded
on the slow-moving tape."
"Can't see anything wrong with it," Carl admitted, "but why don't we use the amplifier in the
"Shame on you for asking instead of thinking!" Jerry chided. "That amplifier probably starts
to fall off pretty rapidly at 100 cycles per second. We need one that will do a good job on 100
cycles per minute. I intend to throw together a little direct-coupled transistorized amplifier,
using both pnp and npn transistors, that will amplify right down to d.c. If we use a cheap, high
output crystal cartridge, we won't need too much amplification. We'll probably have to change
that recording head to a low-impedance transistor type, but fortunately I've got a spare."
Before they went to bed that night, the whole project was completed, even to testing. The slightest
movement set the weighted wire to bobbing, and this put a signal on the creeping tape that came
out as a quickly damped "beep" when the tape was played back on their conventional recorder.
When the boys took their equipment housed in a sturdy weather-proof box to the bridge the next
morning, .they found that Mr. Butcher was as good as his word. The a.c. line was ready and waiting
for them at the end of the bridge. Under the curious gaze of the farmer, they fastened the box
securely to the upper timbers of the bridge near the center of the span. The recorder was plugged
into the a.c. line, and ropes carrying "Keep Off" signs were stretched across both ends of the
"We'll let the recorder run for forty-eight hours and then see what we've got," the boys told
the farmer. "That's about all the time we'll have before heading back to school."
It that on the morning the recorder was to be picked up Carl had to drive over to a neighboring
town for his father. It was almost one o'clock when he came dashing into the basement laboratory
and found Jerry anxiously awaiting him.
"Boy, I'm glad to see you!" Jerry exclaimed. "Mr. Butcher chickened out on presenting our recording
to the commissioners. Says he would ball things up because he knows nothing about electronics.
We have a one-thirty appointment with them at the court house."
The three commissioners and the county engineer received the youths with poorly concealed smiles
of amusement when the boys explained that they wanted to present evidence that the old covered
bridge was settling. However, the men showed mild interest as Jerry set up the transducer on a
heavy table in front of them and connected it to the slow-speed recorder.
Next, Jerry slid a single postcard under one leg of the table. Then a short endless loop of
tape was placed in the recorder, the wire was allowed to come to rest, and then the card was pulled
from beneath the leg. The one-hundredth of an inch of vertical movement at one corner of the table
set the wire to bobbing. When it finally came to rest again, Jerry transferred the loop of tape
to the normal recorder and let the commissioners hear the beep of sound produced by the slight
vertical movement of the table.
Finally, he put the tape that had been recorded in the bridge over a 48-hour period on the
conventional recorder. During the six minutes it ran, beep after beep was heard, indicating that
the bridge was settling a trifle every few hours. Just at the end of the recording, there was
some Donald Duck quacking which sounded like nothing that had gone before.
"What's that?" one of the commissioners wanted to know.
"Oh, it's just some voice recording that got in on the end of the tape," Jerry explained hurriedly.
"You wouldn't want to hear it."
"How do you know we wouldn't?" the commissioner said suspiciously. "Can you make it understandable?"
probably could by playing the tape at a slower speed," Jerry admitted with obvious, very obvious,
"Well, do it then," the commissioner snapped.
Jerry switched the recorder from 7 1/2 ips to 1 7/8 ips, and the voices on the tape came out
clearly and distinctly. Carl recognized one voice as Mr. Butcher's, and the other apparently belonged
to a neighbor he had encountered in the bridge.
"Well, guess the commissioners are going to let the old bridge fall down," the first voice
"Seems like it," the other agreed. "Too bad some people care nothing about tradition and history.
People drive hundreds of miles to take pictures of this bridge. And it means still more to folks
around here. Why, half the men in the county learned to swim beneath it."
"I'm one, and you're another. What's more, I proposed to my wife inside that bridge. Seems
a pity three short-sighted, bull-headed men can destroy something that means so much to folks
who elected them."
"Maybe that's an idea. The election will be rolling around before we know it. Let's forget
party lines, as far as commissioners go, and turn these jokers out and put in men who promise
to do something about the bridge. Suppose we start right now talking it up among our neighbors
"That's a fine idea! I'll start the ball rolling at our grange meeting next Friday. Well, got
to be going now. Be seeing you."
Jerry switched off the tape recorder and began collecting his equipment. Out of the corner
of his eye he could see the three commissioners in a whispered colloquy.
"Hm-m-m-m !" the one who had been so insistent on hearing the voices said eventually; "boys,
your scientific demonstration has been most convincing. It has convinced us that the bridge needs
attention immediately. We are hereby instructing our engineer to go to the bridge at once and
make a careful study to see what is needed to restore it to its original strength and condition,
being careful not to impair its historical significance. As soon as we have his report, work will
While the boys were loading their equipment back into the car, Jerry could feel Carl's eyes
looking at him suspiciously. Finally Carl exclaimed:
"There's some hanky-panky going on here. You know audio frequencies would never record on that
tape at that slow speed. Furthermore, that transducer is no mike. Finally, even if the voices
did record at one-half inch per minute, you couldn't play them back at 1 7/8 inches per second
and make sense. Come on; give!"
"I didn't say the voice recording was picked up by the transducer; the commish just jumped
to that conclusion," Jerry said with a grin. "Actually I had Mr. Butcher and a crony record that
conversation on our regular recorder when I picked up the other equipment. They did darned well
without a script. I just had a hunch the commissioners might not be thoroughly convinced by scientific
proof; so I decided to include a little something they would be sure to understand. "
"And you sure did! Come on; let's go tell the good news to Mr. Butcher!"
Jerry: Their Complete Adventures is now available. "From 1954 through 1964, Popular Electronics published
119 adventures of Carl and Jerry, 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 Beach Buggy
- September 1956
- Extra Sensory Perception
- December 1956
- Trapped in a Chimney
- January 1956
- Command Performance
- November 1958
Education, July 1963
- Treachery of Judas,
- The Sucker, May 1963
Stereotaped New Year, January 1963
- The Snow Machine, December 1960
Extracurricular Education, July
- Slow Motion for Quick Action,
- Sonar Sleuthing, August
- TV Antennas, August 1955
Succoring a Soroban, March 1963
"All's Fair --", September 1963
Operation Worm Warming, May 1961
- The Crazy Clock Caper, October 1960
- Two Detectors, February 1955
Tussle with a Tachometer, July 1960
- Therry and the Pirates, April 1961
The Sparkling Light, May 1962
Pure Research Rewarded, June 1962
Hot Idea, March 1960
- The Hot Dog
Case, December 1954
- A New Company
is Launched, October 1956
the Mistletoe, December 1958
Eraser, August 1962
- Blubber Banisher,
- "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
Posted April 2, 2014