April 1963 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.
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
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
Carl & Jerry: Slow Motion for Quick Action
By John T. Frye W9EGV
Carl 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 shower."
"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
"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
"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
"I'm not sure I understand," Jerry said politely.
"You 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?"
"We 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 recorder?"
"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 structure.
"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
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
"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?"
"I probably could by playing the tape at a slower speed," Jerry admitted with obvious,
very obvious, reluctance.
"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
"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
"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 and friends."
"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 begin."
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!"
Posted April 2, 2014
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 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,
- Electronic Trap, March
- Geniuses at Work, June
- Eeeeelectricity!, November
- Anchors Aweigh, July
- Bosco Has His Day,
- The Hand of Selene,
- Feedback, May 1956
- Abetting or Not?, October
- Electronic Beach
Buggy, September 1956
- Extra Sensory
Perception, December 1956
- Trapped in a Chimney,
- Command Performance,
- Treachery of Judas, July
- The Sucker, May 1963
- Stereotaped New
Year, January 1963
- The Snow Machine, December
Education, July 1963
- Slow Motion for
Quick Action, April 1963
- Sonar Sleuthing, August
- TV Antennas, August 1955
- Succoring a Soroban,
- "All's Fair --", September
- Operation Worm Warming,
Stomping, March 1962
- The Blubber Banisher,
- The Sparkling Light, May
- Pure Research Rewarded,
- A Hot Idea, March 1960
- The Hot Dog Case, December
- A New Company is Launched,
- Under the Mistletoe,
- Electronic Eraser,
- "BBI", May 1959
- Ultrasonic Sound Waves,
- The River Sniffer, July
- Ham Radio, April 1955
- El Torero Electronico,
- Wired Wireless, January
- Electronic Shadow,
- Elementary Induction,
- He Went That-a-Way,
- Electronic Detective,
- Aiding an Instinct,
- Two Detectors, February
- Tussle with a Tachometer,
- Therry and the Pirates,
- The Crazy Clock Caper,