April 1956 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.
can buy a pretty good metal detector today for a hundred dollars
that will find coins buried many inches deep and larger metallic
items even deeper, and you even get discriminator functions
to filter out unwanted objects like tin cans. They weigh just
a couple pounds and can be used with one arm. Compare that to
early metal detectors that had huge induction coils on a frame
so heavy that shoulder straps were needed just to lug them around.
Some models came on wheels for pushing or pulling like a cart.
You could plan to spend a few hundred dollars
(a thousand or more in today's dollars)
for one. Even then, they were not as sophisticated as the $50
models sold in Walmart now. In classic fashion, teen electronics
hobbyists Carl and Jerry use their technical prowess to design
and build their own metal detector and then unintentionally
using it to convince some old geezer that newfangled devices
were not all useless fluff.
Carl and Jerry: Gold Is Where You Find It
By John T. Frye
bright first-day-of-April sunshine put new life into a fellow;
so Carl vaulted nimbly over the low fence that separated his
yard from that of his chum, Jerry Bishop. But he stopped short
as he caught sight of his friend out on the lawn near the street.
On Jerry's head was a pair of huge muff-type airplane earphones
that were plugged into a small aluminum box slung from his shoulder.
From this box a cord led to the strange device he held in his
hands. It consisted of a long broom handle attached to the crosspiece
on a large, flat wooden hoop so as to hold this hoop parallel
to the ground. Jerry's round face wore a faraway look of abstract
concentration as he shuffled along, waving the hoop back and
forth over the sprouting grass.
"Hey, Jer, what're, you doing?" Carl demanded, when he managed
to catch Jerry's vacant eye.
"What did you say?" Jerry asked, sliding the phones forward
on his head so that he could hear.
"I asked what you thought you were doing with that contraption."
"You mean my worm-warmer here?" Jerry asked, with bland innocence.
''I'm just doing my bit for be-kind-to-worms-week. This is an
r.f. induction coil that heats the ground beneath it and makes
things comfy for the poor little worms that are still chilled
"Ask an intelligent question and you get a smart answer,"
Carl muttered. "Are you going to tell me what that thing is,
or am I going to have to squeeze that narrow hoop down over
your fat and flabby body?"
"All right; this is a metal locator. I built it from an article
by Harvey Pollack that appeared back in the June, 1955, issue
of Popular Electronics."
"How does it work?"
"Inside this aluminum box is an oscillator operating on about
two megacycles. Shielded from it is another oscillator whose
tank coil, electrostatically shielded, is wound inside this
wooden hoop. Shielded wire connects the outboard tank coil to
the rest of its circuit inside the box. The two oscillators
are tuned to very nearly the same frequency, so that a low audio
difference-frequency beat note is produced by them. This beat
note is detected, amplified, and fed to the earphones. When
a metallic object appears in the extensive field of the large
coil in the hoop, its presence affects this field and so causes
a slight frequency shift in the oscillator connected to it.
This, in turn, produces an easily detected change in the beat
note frequency heard in the phones and warns the operator that
the probe coil is nearing some metallic object. Here," Jerry
said, as he freed one of the earphones from the headband; "you
walk along behind me and listen, and I'll show you what I mean."
When Carl held the earphone to his ear, he heard a low-pitched
musical tone. Suddenly, as Jerry moved the hoop over the grass,
the note rose to a high pitch; then it went back down as Jerry
kept walking. Probing the area with the coil established that
there was a line perpendicular to the curb which gave the same
high-pitched sound as the probe was moved along the narrow path;
but if the coil were moved to either side of this path, the
note in the phones returned to the normal low value.
"What's down there?" Carl asked.
In answer, Jerry followed the invisible object beneath the
surface with the metal locator right to the curb, where a large
"G'" was chiseled in the cement.
Jerry's round face wore a faraway look of abstract concentration
as he shuffled along, waving the wooden hoop back and forth
over the sprouting grass.
"It's the gas line," he explained. "The gas people marked
the curb this way when the cement street was laid so that-they
could find their service lines easily."
"What else is the gadget good for.?" . "Locating electric
cables and pipes in walls or finding any metallic objects buried
in the ground, such as pipes, tanks, or - "Jerry paused dramatically:"
- buried treasure!"
Carl's eyes opened wide behind his horn-rimmed glasses. "You're
holding out on me!" he accused. "Give!"
Jerry leaned on the handle of the metal locator as he talked:
"Saturday, a week ago, old Mr. Gruber and I went up Eel River
to the mouth of Tick Creek fishing. They didn't bite very lively,
and we did a lot of talking. For once I managed to get him off
his favorite subjects of flying saucers and space travel, and
he told me an old legend he had heard from his father.
"A flock of years ago, the government bought all this land
from an Indian tribe that lived on it. The government paid the
Indians $80,000 in gold and gave them a new reservation in the
Northwest. An escort of soldiers was to accompany the tribe
to its new home.
"While still in the assembly encampment, the Indians heard
the soldiers talking and decided, rightly or wrongly, that these
soldiers planned to rob them of their gold on the journey; so,
secretly, during the dead of night, the elders of the tribe
buried the gold on the banks of Eel River. Unfortunately, smallpox
broke out among the Indians on their march to their new home,
and not a single member of the party that buried the gold survived;
consequently, it's still there waiting for someone to find it
"According to Mr. Gruber, when he was a boy, he and his friends
used to hunt for the gold all up and down the river. Later,
when he. was grown, the legend became a sort of hobby with him,
and he read every scrap about it he could find. Out of this
study came the conviction that the assembly encampment must
have been very near the mouth of Tick Creek and that the gold
is buried in that vicinity. Of course, this still leaves a lot
of territory to be explored by tedious digging; but with a gadget
like this, a person could go over a lot of ground in a hurry
"Well, what are we waiting for?" Carl demanded. "I'll get
a couple of shovels and a pick, and a tow sack to bring back
the loot, and you get your bike. Yo ho ho, and a bottle of rum!"
Tick Creek emptied into Eel River only a short distance above
the town; so within the hour the boys had hidden their bicycles
in the bushes along the road and were trudging across the cornfield
that lay between the road and the thin line of trees. marking
the river bank.
"Hey, Jer," Carl said, as he strode along with the digging
tools cradled in his arms, "do you think we ought to ask permission
from Mr. Sloan, who owns this farm, before we start looking
for the gold?"
"Naw," Jerry replied. "In the first place, he's an old crab
and would say no automatically. Then, too, I'd feel kind of
silly telling him we wanted to go treasure hunting on his farm.
He'd think we'd both blown our corks for sure. Of course, if
we find anything, we'll tell him and divide up with him."
By the time this serious matter was settled, the boys had
reached the point where shallow Tick Creek flowed into Eel River,
thrusting a flat sandbar halfway across the larger stream. Jerry
at once unlimbered his metal locator and began a systematic
survey of the area, while Carl tagged along at his heels breathing
down the back of his neck: The boys had been prospecting for
scarcely ten minutes when Jerry suddenly stopped dead in his
tracks so abruptly that Carl stumbled into him.
"What is it? What do you hear?" Carl shouted anxiously.
"There's something down there," Jerry said slowly, as he
moved the probing hoop around , in an exploring circle. "It's
right here, and it seems to be about as big around as a small
As Jerry finished speaking, Carl thrust him aside and began
digging feverishly at the spot where the metal locator had given
the strongest indication. Even Jerry, who ordinarily had a strong
aversion to any kind of physical exercise, grabbed up the other
shovel and began turning over the soft earth. The boys quickly
sank a shaft about three feet in diameter, and when it had reached
such a depth that the edge of the hole came about to Carl's
chest, his shovel suddenly gave forth with the hair-raising
sound of metal scraping on metal.
"Easy now," Jerry admonished, as he knelt at the, side of
the hole and peered intently down to where Carl was gently scraping
the dirt away with the edge of the shovel.
"Aw, heck!" Carl suddenly said, with deep disappointment.
"It's just a roll of old fence wire."
"And what did you expect?" a gruff voice asked from behind
The heads of both boys jerked up to see a scowling farmer,
carrying a pitchfork, towering over them.
"What do you young rascals think you're doing?" he demanded.
"Now, climb right out of that hole and start filling it up.
You think I want one of my cows stepping in that and breaking
her leg and making it necessary for me to destroy her? What
are you trying to do, anyway?"
As the boys meekly started shoveling the earth back into
the hole, they told him about the legend and tried to explain
the operation of their metal locator.
"A likely cock-and-bull story!" Mr. Sloan sneered. "I've
never held with these scientific gadgets since I gave a fellow
with a peach tree fork ten dollars to twitch a well site for
me. We drove straight down a hundred and forty feet right where
he said and never struck a drop of good water. You just gather
up your junk, and I'll personally escort you off my property.
And if you know what's good for you, you'll never set foot on
Jerry rigged himself up in his metal locator, and Carl gathered
up the tools. All three started across the cornfield toward
the road, with Mr. Sloan - his pitchfork cradled in the crook
of his arm - following behind Jerry. When they were about halfway
across the field, Jerry stopped so abruptly that Mr. Sloan narrowly
averted thrusting the tines of the pitchfork into the boy's
"What are you trying to do ... make me hurt you so you can
sue me?" Mr. Sloan bellowed. "Keep moving."
"Wait a minute," Jerry said, as he moved the search coil
about over the broken cornstalks. "I'm getting an indication
of something down here."
He set the probe down, dropped to his knees, and began to
scrape away at the soft earth where he had obtained the strong
reading. In a moment he stood up, dangling something from a
dirt-encrusted chain that glinted yellowly in the sun.
"Here, let me see that," Mr. Sloan said sharply. He brushed
aside more of the clinging dirt and then exclaimed, "Well I'll
be danged if it's not my pappy's old watch that I lost when
I was checking corn last spring. I sure thought I'd never set
eyes on it again, and that grieved me sorely, for I put a great
store in that old turnip. The case is heavy gold, and it was
given to my father by my mother on their wedding day. See, here's
an inscription on the inside. I wouldn't trade it for the finest
diamond-studded watch you could buy."
He paused a moment and then went on:
"I'm mighty obliged to you boys for finding it for me, and
here's five dollars each for you. Take it; I won't have it any
other way. What's more, I'm downright ashamed of acting so crabby
with you before."
"Aw, that's all right, Mr. Sloan," Jerry said. "We really
should have asked your permission before we trespassed on your
property anyway. What tickles me, though, is that we were able
to prove to you that this gadget, unlike that fellow's peach
tree fork, really does what it's supposed to do."
"Well, you certainly convinced me," Mr. Sloan said heartily,
with a broad and friendly grin; "and I'll tell you what! I have
to take a load of steers to the sales barn today; but if you
fellers can come back tomorrow afternoon, I'll get my shovel
and go along with you, and we'll comb this old farm of mine
with that gold-sniffing gadget of yours to a fare-you-well ...
that is, if you don't mind letting a crabbed old cuss like me
in on the fun.'"
"Tickled to have you, Mr. Sloan!" the boys chorused together.
"I'll be danged if it's not my pappy's old watch that I lost
when I was checking corn last spring."
Posted August 27, 2015
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,
Education, July 1963
- 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,