March 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.
Throughout John T. Frye's series of "Carl and Jerry" stories, there are
times when one or the other needs to convince his technosleuth buddy that a
particular project is worthy of undertaking. In the early days while the boys
were still in high school, Jerry was typically portrayed as an overweight,
rather lazy guy who, while well versed in electronics and mechanics, preferred
to do his thinking and acting while sitting or lying down. He always rose to the
event and did his part to solve a crime, play a joke on a friend, or solve a
problem plaguing their combined interest in amateur radio and remote controlled
model boats and airplanes. By the time they got to Parvoo* University as
electrical engineering students, he had outgrown most of those tendencies. In
this 1963 issue of Popular Electronics magazine is an example of Jerry
being the motivator and "expert" on the subject of atomic magnetometers. With
the ready availability of low noise, high gain opamps and cheap audio frequency
digital oscilloscope systems, I wonder why the described type of atomic metal
detector is not widely used today, rather than the classic magnetic coil?
*Some believe Parvoo is a play on
Purdue, in Indiana, where the boys lived.
Carl & Jerry: The Educated Nursing Bottle
A Carl and Jerry Adventure
By John T. Frye W9EGV
Carl and Jerry, on their way home from Parvoo University for Easter vacation,
were driving the back roads, enjoying the budding signs of spring so welcome after
the long and bitter winter.
"Well, what do we do this vacation?" Carl asked as they rolled along a gravel
road. "I'd like to forget all about books for a few days and build something wild
in the lab the way we used to."
"We'll think of something," Jerry promised. "Say, what's that funny-looking little
hill in the field over there to the left?"
"That's an old Indian burial mound," Carl replied. "I used to hunt arrowheads
on it when I visited a cousin living near here."
"Hey! That reminds me. Did you ever hear of a Differential Proton Precession
"Nope," Carl confessed, "and I wouldn't wish a name like that on a dog. Anyway,
what's the connection between Indian mounds and your proton whatchamaycallit?"
"I read in the November, 1963, issue of the Indiana History Bulletin that such
an instrument is being used to make a magnetic survey of the big Angel Mounds archaeological
site in the southern part of the state. Mr. Glen A. Black is directing the operation
for the Indiana Historical Society, and he wrote the article which got me curious.
I've been doing some digging - no pun intended and I find the proton magnetometer
a very interesting gadget."
"Try and convince me," Carl challenged.
"O.K. The proton magnetometer was developed at Oxford University. It's essentially
a device to accurately measure very small magnetic fields, such as the fraction
of a gauss-between 49,000 and 61,000 gammas - presented by the earth's magnetism.
The funny part about the whole thing is the 'complicated' basic apparatus: it consists
of a coil of wire wound around a half-pint plastic bottle of water!"
"Go on. Now you've got me curious," Carl admitted.
"The proton, or hydrogen nucleus, acts like a tiny bar magnet spinning on its
long axis. It has both magnetic and gyroscopic properties. As a magnet, it aligns
itself with the magnetic field of the earth in its locality just like a compass
needle. If it's temporarily twisted out of alignment, it 'gyrates' back into line
with the wobbling motion of a spinning top. The frequency of those gyrations is
directly proportional to the strength of the magnetic field."
"Where does the jug of water and the coil come in ?"
"Water is two-thirds hydrogen atoms, and a half-pint contains a billion billion
protons, give or take a proton or so. Now if you send a direct current through
the coil of wire around the bottle for a few seconds, the resulting magnetic field
twists the protons out of alignment with the weaker magnetic field of the earth.
Remove the current and the protons start waltzing around to get back into their
original position. The moving, combined magnetic field of all those gyrating protons
cuts the turns of the coil and produces a small a.c. voltage in it. The frequency
of that voltage is an exact indication of the strength of the magnetic field."
"That's neat!" Carl exclaimed. "How's it used in archaeology ?"
"It was first put to use at Sybaris in southern Italy. In the sixth century B.C.,
enemies from the neighboring city of Croton destroyed Sybaris, leveled it, and diverted
the Crathis River to flow over the site and cover it with silt."
"I somehow get the feeling the Crotoni didn't like the swinging Sybariti very
"You better believe it. Anyway, the archaeologists didn't know where to look
for the buried ruins. Italian soil in this region is magnetic, but the limestone
from which the Sybarites originally built their wall is not. When they surveyed
the flat plain of the ancient river with the proton magnetometer they found abrupt
changes in the magnetism of the ground below by which they could trace the location
of the buried wall for nearly a mile.
"Three different proton magnetometers have been used at Angel Mounds here in
Indiana with pretty good results. The first was the Model M-49 built by Varian Associates
of Palo Alto, California. Another was an English model, the Elsec 592/A, built by
Littlemore Scientific Engineering Company. The one they're using now, the LMB II,
was built by a man named Scollar at the Rheinisches Landesmuseum in Bonn, Germany.
All three will show the presence of many buried materials by indicating slight differences
in the strength of magnetic readings taken directly above."
"That's it!" Carl exclaimed. "We'll build a proton magnetometer and survey that
Indian mound back there!"
"Now hold on," Jerry demurred. "The proton magnetometer is simple in theory but
very sophisticated in practice. The voltage output of the coil is only about a microvolt.
That means you need a lot of noise-free amplification before you can measure the
frequency. And you should measure that frequency to approximately one part in 25,000.
Protons normally make about 2000 gyrations per second at the earth's surface. A
typical reading would be 2000.64 cycles per second. Increasing the magnetic field
five gammas (0.00005 gauss) raises the frequency only to 2000.84 cycles. Being able
to measure point-two of a cycle change at that frequency takes real good equipment."
"Aw come on! Don't tell me Parvoo has educated the experimenter out of you. We
used to do a lot of things because we didn't know they couldn't be done. Where's
your old make-do spirit?"
"O.K., O.K.! You've made your point.
I'm game. I admit I have a couple ideas I'd like to try."
"So what are we waiting for?" Carl asked with a pleased grin as his foot mashed
down on the accelerator.
THE FIRST THING the boys did the next morning was buy a plastic nursing bottle
and wrap the whole length of it with No. 22 enameled wire and connect the ends to
a coaxial fitting. The next few hours were spent revamping a high-gain transistorized
amplifier they had built previously. They installed their best low-noise transistor
in the front end and used tuned circuits to peak the amplifier fairly sharply at
2000 cycles to get maximum gain. Finally they were satisfied that the one-microvolt
signal from the coil would produce the 30 millivolts or so Jerry said they needed.
"How are we going to measure the frequency ?" Carl wanted to know.
"We don't need to measure the frequency - all we need to know is the relative
frequency change produced by a change in the magnetic field around the bottle. We'll
use Lissajous figures."
While talking he hooked the output of a code practice oscillator to the horizontal
amplifier of the scope and adjusted the gain for a one-inch horizontal trace. The
variable sine-wave generator was connected to the vertical amplifier and the gain
adjusted for a one-inch vertical trace. When both signals were going through the
amplifiers, a one-inch square of light filled with moving lines appeared on the
scope face, but when Jerry set the frequency of the generator exactly to that of
the code practice oscillator, a kind of nervous circle was displayed. The slightest
change in the generator frequency set this hoop of light to turning one way or the
"That circle shows both oscillators are running at the same frequency with a
ninety-degree phase shift," Jerry said, thinking out loud. "The slightest difference
in frequency will set the pattern moving, and the number of revolutions it makes
a second is the number of cycles of difference. If it takes ten seconds to make
a revolution, that means there's only one-tenth of a cycle difference between the
two frequencies, right ?"
"Right. So what next, genius?" Carl asked.
"Let's get busy and build the most stable 2000-cycle audio oscillator we can.
We'll use a vernier control so we can vary it a few cycles either way."
They decided on a Wien-bridge oscillator and built it as ruggedly as they could,
using air-dielectric capacitors, precision resistors, and VR tubes to hold the voltage
steady. A small variable capacitor permitted the frequency to be varied a few cycles
in either direction. The completed oscillator was connected to the horizontal scope
Coaxial cable from the coil around the bottle went to a switching box. When a
button on this box was pushed, an ampere of current from a battery was sent through
the coil. Releasing the button connected the coaxial cable to the input of the transistorized
amplifier going to the vertical scope amplifier. After the bottle was filled with
water and placed on the floor in an east-west position, Jerry held the button down
for six seconds and then released it while both boys eagerly watched the scope.
The horizontal line traced by the audio oscillator expanded to a rectangle, held
there for a few seconds, and then slowly collapsed.
"We're getting a signal from the coil!" Jerry exulted. "Now let's see if we can
tune our oscillator to the frequency put out by the protons."
This took several tries, but finally they managed to get the desired glowing
circle on the face of the scope every time the button was pushed and released. It
was rather fuzzy-looking, indicating the presence of some noise, but it served the
A magnet from an old speaker was placed on the floor near the bottle, and now
when the button was pressed and released, the scope pattern revolved rapidly, showing
a decided change in the frequency from the bottle. The audio oscillator frequency
had to be increased several cycles to restore the circle to the face of the scope.
Moving the magnet away from the bottle lowered the frequency.
"We're in!" Carl gloated. "Tomorrow we'll take it out to the Indian mound and
start digging up buried treasure!
THE NEXT MORNING, low gray clouds were scudding across the sky and the south
wind smelled of rain. Despite the unpromising weather, however, the boys couldn't
wait to try their "bottle prospecting," as Carl termed it, and they loaded their
gear into the car and took off.
The farmer on whose land the mound stood readily gave them permission to try
out their proton magnetometer, and even let them drive down a lane to the base of
the mound. This helped, because they had borrowed a small, but heavy, gasoline-powered
generator from the amateur radio club to power the non-transistorized equipment.
Jerry fired this up in the trunk of the car and ran an extension cord from it to
a card table set up near the bottom of the grassy knoll. The scope, audio oscillator,
and preamplifier were placed on the table and turned on. A couple of hundred feet
of RG58/U coaxial cable connected the sensing unit to the amplifier.
After everything was thoroughly warmed up, Carl carried the bottle about a hundred
feet up the slope of the mound and placed it, pointing in an east-west position,
on the ground. Jerry had no trouble in synchronizing the audio oscillator with the
signal sent back from the bottle after the button was pushed and released.
While the farmer watched curiously, Carl moved the bottle about ten feet, and
Jerry took another reading. The pattern moved ever so slowly until Jerry stopped
it by readjusting the oscillator. They repeated this process several times without
finding any indication of a sharp change in the magnetic field.
In the meantime, the sky was growing darker and the wind was picking up. Carl
began working down the slope toward the card table.
"Hold it! The pattern's spinning like a merry-go-round!" Jerry suddenly shouted.
"Move the bottle back to where it was and make sure our oscillator frequency hasn't
But when the bottle was returned to the
previous spot, the familiar fuzzy circle appeared on the scope. A few more readings
revealed a small area about a yard in diameter of sharply increased magnetism. The
boys hastily got spades from the car, and the farmer ran to the barn to get his
shovel. All three started digging furiously.
At a depth of only a few inches they ran into some cans, but the "bottle prospector"
showed that the magnetic object was still in the earth below. Then the farmer's
shovel struck rotting wood. The boys watched intently as he carefully moved aside
the soft earth and revealed - an old-fashioned wall-type telephone! A single check
with the magnetometer revealed that this was the source of the magnetism, and at
this moment great drops of rain began spattering down.
The farmer helped the boys hurriedly place their equipment inside the car,
and then he got in with them as a heavy shower drummed on the roof.
"Now I recall we had a trash pit there when I was a kid," the farmer mused. "I
can't rightly remember how that old telephone got there, but I reckon the telephone
company just left it when new phones were put in."
"And after all these years the magnets in that crank-type ringer magneto still
have enough moxie in them to drive the scope crazy," Jerry said. "Well, we didn't
find any buried treasure, but our do-it-yourself proton magnetometer sure works."
"I'm satisfied," Carl admitted, gazing fondly at the wire-wrapped nursing bottle
he held in his hand.
Posted November 7, 2023
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.
- See Full List -
Carl & Jerry, by John T. Frye
Carl and Jerry Frye were fictional characters in a series of short stories that
were published in Popular Electronics magazine from the late 1950s to the early
1970s. The stories were written by John T. Frye, who used the pseudonym "John T.
Carroll," and they followed the adventures of two teenage boys, Carl Anderson and
Jerry Bishop, who were interested in electronics and amateur radio.
In each story, Carl and Jerry would encounter a problem or challenge related
to electronics, and they would use their knowledge and ingenuity to solve it. The
stories were notable for their accurate descriptions of electronic circuits and
devices, and they were popular with both amateur radio enthusiasts and young people
interested in science and technology.
The Carl and Jerry stories were also notable for their emphasis on safety and
responsible behavior when working with electronics. Each story included a cautionary
note reminding readers to follow proper procedures and safety guidelines when handling
Although the Carl and Jerry stories were fictional, they were based on the experiences
of the author and his own sons, who were also interested in electronics and amateur
radio. The stories continue to be popular among amateur radio enthusiasts and electronics
hobbyists, and they are considered an important part of the history of electronics
and technology education.
Educated Nursing - April 1964
- Going Up
- March 1955
Shock - September 1955
- 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
The Electronic Bloodhound - November 1964
Great Bank Robbery or "Heroes All" - October 1955
Operation Startled Starling - January 1955
- A Light
Subject - November 1954
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."