May 1960 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
Before a plethora of
readily available and affordable electronic and mechanical components of all
sorts was at your fingertips (on a keyboard), often times project builders and
repairmen either did without, substituted "close enough" parts, waited a long
time for mail order, drove long distances to a supply house, or did like Carl
and Jerry did in this May 1960 Popular Electronics magazine adventure -
they modified on-hand equipment to suit the need. Replacing the center conductor
of a length of RG-58 coaxial cable in order to change its capacitance (and
impedance) might seem like an extreme measure to take, but half a century go it
was de rigueur with hobbyist of all sorts. Magazines of the era nearly always
had monthly hints, kinks, tip, and suggestions features, enthusiastically (and
sometimes motivated by a nominal monetary reward) provided by readers who had
already reaffirmed the old adage of necessity being the mother of invention. As
is author John Frye's normal practice, the reader is also treated to a lesson on
an electronics subject, in this case a heterodyne system.
A comprehensive list of all the Carl & Jerry episodes posted on
RF Cafe is at the bottom of the page.
Carl & Jerry: The Black Beast
By John T. Frye W9EGV
The bright May morning found Carl and Jerry furiously pedaling their bicycles
along a dirt road paralleling the river west of their home town.
"As I told you," Carl was explaining to his puffing companion, "yesterday afternoon
I was trying out my new spinning reel along the path that runs between the bottom
of the limestone bluff and the river. On the very first cast I let go of the line
at the wrong time, and my favorite fla-fish lure sailed backwards into some scrub
trees growing right against the base of the cliff. In trying to free the lure, I
spied this narrow opening that looks like the mouth of a cave. I didn't have a flashlight;
it was getting late; I knew my favorite pal would want to explore the cave with
me; so I came home."
"What you really mean is that you were scared to go in by yourself," Jerry said
with a sniff as he braked his bicycle to a sliding halt at a point where a steep
path led down to the river.
Carl led the way down this path and then along a narrow, rocky ledge between
the water and the cliff for a hundred yards or so. Then he clawed his way through
some stunted trees and thorn bushes, and finally stopped triumphantly in front of
an opening a couple of feet wide and about six feet high in the white limestone
wall. The boys turned on their flashlights and very cautiously entered the narrow
tunnel. It twisted and turned for some hundred feet and then suddenly emerged in
a domed, nearly circular room at least twenty feet in diameter.
"Hey, Jer, look at that!" Carl breathed in a
hoarse whisper as his flashlight beam came to rest on a dim, crude picture painted
on the smooth white wall of the cave. As the circles of light from the two flashlights
followed each other around the room, paintings and drawings as high as a man could
reach were revealed on the walls.
"They must have been painted by Indians many years ago," Jerry whispered, shivering
in the chill damp air of the cave. "Hey! What are we walking on?" he exclaimed as
he tripped over something.
Carl shined his light down at their feet and then said softly, "Oh, oh!" The
floor of the cave was strewn with large bloody bones with bits of flesh still clinging
"Man, let's get out of here," Carl exclaimed as he headed for the tunnel opening.
"Maybe the-the-the thing that lives here comes home for lunch."
The boys left the cave a lot faster than they had entered it.
"No ninety-pound weakling lives in there," Jerry asserted. "Those bones belonged
to an animal at least cow-size."
"Yeah, and look at this," Carl added as he reached up and plucked a tuft of black
coarse hair from a thorny branch hanging down over the cave. "Whatever it is, it's
black and hairy and taller than we are."
"A black beast!' Jerry exclaimed in awe as he stared at the lock of hair in Carl's
hand. "Let's find out what it is!"
"Like how?" Carl questioned dubiously.
"Hm-m-m-m, that's a good question. We can't stay down here and watch the cave
without danger of the thing's scenting us."
"And probably gnawing on us like he did on those bones," Carl added. "But we
can't watch from the top of the bluff because that overhang of rock conceals the
cave mouth from sight up there."
"I got it!" Jerry exclaimed. "Remember when we used a simple capacitance relay
to make that chicken-stealing coon at my uncle's farm take his own picture? Well,
I've been experimenting with a new-type capacity relay described in the February
Electronics World. We can camp safely on top of the bluff and let this
relay tell us when anything or anyone enters the cave."
"What's special about this relay?"
"The sensing probe can be some distance from the relay and connected to it through
a coaxial cable. The relay has two identical low-frequency r.f. oscillators: one
fixed-tuned with a 300-µµf. capacitor, and the other tuned by a semi-variable capacitor
in parallel with the capacitance of the coax line. This oscillator is set about
1000 cps higher in frequency than the fixed oscillator. The heterodyned difference
beat between the two oscillators is amplified and fed through a low-pass filter
to the control grid of a thyratron tube with a relay in its plate circuit.
"As long as nothing is near the probe, the low-pass filter prevents the 1000-cycle
signal from reaching the thyratron and firing it; so the relay contacts remain open.
When a body approaches the sensing probe, the additional capacity thus produced
lowers the frequency of the tunable oscillator and also the difference-frequency
heterodyne fed to the amplifier. This lower frequency passes readily through the
filter, fires the thyratron, and closes the relay.
"There's only one joker," Jerry added thoughtfully as his eye measured the distance
between the cave and the overhanging ledge. "The RG-8/U coaxial cable I've been
using has a capacitance of 29.5 µµf. per foot. It's about twenty feet from the cave
to that overhang where we could conceal the gadget and then run lamp cord from the
relay contacts on up to the alarm at the top of the bluff."
"And 20 times 29.5 is 590 µµf.-far in excess of the 300-µµf. total capacity required
to tune the oscillator to the right frequency," Carl finished.
"Of course, there are special coaxial cables with less capacity, but none in
"I can solve your problem!" Carl interrupted as he started back toward the path.
"I'll tell you about it on the way home."
Once home, they set feverishly to work. A twenty-foot
length of RG-8/U was firmly anchored at one end and the remainder stretched out
straight. The anchored end had its inner conductor tinned and a No. 30 wire carefully
soldered to it. Heavy leads from a low-voltage high-current transformer were run
to the two ends of the center conductor. By means of an autotransformer in the primary
circuit, the current through the inner conductor was gradually increased until the
conductor grew noticeably warm. Carl watched the dielectric material around the
conductor carefully, and when he decided it was softened the proper amount by the
heat, he unsnapped the leads from the transformer, grasped the end of the conductor
with a pair of vise-grip pliers, and, walking backwards, easily pulled the conductor
out of the cable and the No. 30 wire into the cable in its place.
Since the capacity of the cable was chiefly a function of the ratio of the inside
diameter of the shield to the diameter of the conductor, replacing the conductor
with the No. 30 wire drastically reduced the capacity of the cable - and incidentally
raised its characteristic impedance. Now, with the reworked cable in place and the
capacitance relay powered from batteries, the oscillator could easily be tuned to
the proper frequency.
Soon the boys were pedaling slowly back toward the cliff burdened with gear for
an overnight camp plus a long length of strong rope and Carl's .22 rifle. They tied
the rope to a tree on top of the bluff directly above the cave, and Carl lowered
himself to the overhang of rock. There he set up the capacitance relay with its
battery power supply.
The coax cable was run down to the cave, and a lamp cord was run to the top of
the bluff from the relay contacts. Both were concealed by vines growing on the face
of the cliff. A small wire was connected to the bottom end of the coax inner conductor
and artfully concealed around the opening in the cliff. Carl adjusted the variable
frequency oscillator so that the relay contacts remained open until Jerry approached
the opening; then they closed. They even closed when he tried to sneak in on his
hands and knees.
The boys pitched their tent right at the edge of the bluff. They connected a
battery and small light bulb in series across the two wires coming up from the relay
contacts and fastened the lamp to the ridge -pole of their little tent. It was dark
by the time they finished supper; and now, with nothing more to do except wait,
the weariness resulting from the day's strenuous activities overtook them. After
fighting sleep for a short time in the warmth of their campfire, they gave up, crept
into the tent, and almost immediately lost consciousness.
When Carl was snapped wide awake some time later
by a light shining in his face, he instinctively felt that several hours had passed.
Reaching over, he roughly poked his still-sleeping companion in the ribs. "Come
on, wake up! Something's entered the cave and turned on the light."
Jerry sat up and rubbed his eyes sleepily. "Maybe we ought to wait until morning,"
he said with a shiver as he looked at the darkness outside.
"None of that!" Carl said sternly. "We go look now before he gets away. Remember
this was your idea."
Stealthily the two boys, Jerry carrying the flashlight and Carl carrying the
rifle, stole down the steep path and back along the narrow strip of rock leading
to the cave. Not a sound could be heard except the singing of the night insects
and the gurgling of the river.
"You go first with the rifle. I'll be right behind you with the light," Jerry
suggested in a shaky whisper as they stopped in front of the yawning, pitch-black
opening in the rock.
"Okay, but just don't get in my way if I suddenly decide I want out," Carl warned.
Slowly and cautiously the two boys entered the tunnel. Carl held the rifle stiffly
out in front of him, and Jerry walked right on his heels with the glowing flashlight
thrust through the crook of Carl's elbow.
Nothing happened until they reached the last right-angle turn in the tunnel.
Suddenly Jerry clutched Carl's shoulder. "Listen!" he hissed. "Didn't you hear something?"
"How can I with you breathing in my ear like an asthmatic grampus?" Carl retorted
as he edged around the turn.
The beam of the flashlight shining across the room revealed nothing, but as the
two boys stepped from the tunnel, a pair of hairy arms reached out from the side
and grabbed both the rifle and the flashlight, wrenched them out of the boys' hands,
and sent the two stumbling forward to their knees in inky darkness. Carl was on
his feet like a cat, but when he turned toward where he thought the tunnel opening
was, he ran against a great hairy creature that smothered him in a vise-like grip.
"Kick him! Bite him, Jer," Carl shouted as he sank his teeth into a loose fold
of the skin of the beast.
"I wouldn't do that," a deep chuckling voice answered. "I don't think my dad
will like it if you chew a hole in his beloved old raccoon coat."
At this instant the flashlight came on and revealed a large smiling young man
dressed in a bulky fur coat. Over at one side of the room was a camera on a tripod.
"So you boys want an explanation, and you've got one coming," the personable
youth went on. "My name is Dick Palmer, and I'm a junior at the state university.
About a month ago I stumbled upon this cave. I have a hunch these pictures were'
made by the mound builders that used to live around here. Photography is a hobby
of mine, and I instantly got the idea of photographing the pictures and selling
them to one of the big picture magazines. I need the money to finish my college
"I've been driving back here every night I could get away from school to photograph
these walls. It took a lot of experimenting with lighting and so on, but I finished
the job tonight. Yesterday afternoon I had a little free time and drove over, but
just as I got here, you," he said, nodding at Carl, "discovered the cave. I simply
had to have a few more hours to finish up; so last night I stopped at a butcher
shop and got a big bag of beef bones to spread around the cave and maybe convince
you that this was the lair of a dangerous animal.
"When I heard you two coming down the tunnel tonight and saw that rifle, I decided
I'd better disarm you first and explain later. You sounded a little trigger-happy."
"Why the fur coat?" Jerry asked.
"It gets darned chilly in here; so I've been wearing the old fur coat dad had
in college to keep me warm. Now I've got a couple of questions. How come you're
prowling around here at midnight, and how did you know I was in here?"
Come on up to our camp on top of the bluff, and we'll show you, and give you
a cup of hot chocolate," Jerry offered.
"And you needn't worry that we'll blab about that cave," Carl added. "You found
it, and it's your secret."
"Fine, men. If I'd known you were that sort, we could have saved all of us a
lot of trouble."
"And goose pimples," Jerry admitted with a grin.
Posted January 28, 2022
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."