November 1956 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.
there are about 350
species of electric fish. Jerry tells fellow electrical and electronics experimenter
Carl that the electric eel is not an eel at all, but a fish. Actually, the eel is
a fish (a knifefish);
however - and I needed to look this up - a true eel is a member of the fish order
Anguilliformes, which the electric eel is not. Having no expertise in the field
of eels, I'll leave it at that. Jerry's uncle, who is an active duty Navy guy, somehow
managed to ship an electric eel to him for experimentation purposes. Doing so might
have been possible in 1956 when this episode of "Carl & Jerry" appeared in
Popular Electronics magazine, but today it is doubtful. Besides that, how
to you mail an electric eel to somebody? The pair's measurements of voltages and
pulse widths jive pretty well with modern data. Here is a story about how
electric eels curl to obtain higher voltages for stunning prey.
Carl & Jerry: Eeeeelectricity!
By John T. Frye
Carl was just arriving home after spending a
short week-end vacation with an aunt and uncle in Chicago. He burst in the front
door, yelled "Hi, Dad," planted an awkward kiss on the bridge of his mother's nose;
and sailed right on out the back door, across the yards, and into the basement laboratory
of his neighbor and best friend, Jerry Bishop.
Jerry was there all right, and he was just as glad to see his pal as Carl was
to see him; but it was against the Code of Boyhood to show their feelings. Jerry
hardly looked up as he grunted a greeting. To tell the truth, though, he was pretty
busy trying to strap a squirming, wriggling something into the concave side of a
short section of gutter trough. It kept slithering through the rubber gloves he
"Holy cow, Jer, what is that thing?"
Carl demanded. "Is it a snake?"
"Of course not, stupid. It's an eel that my uncle in the Navy sent me from South
America. I want to make some tests on it. Put on that other pair of rubber gloves
and help me fasten it in this trough."
"Not on your life!" Carl said emphatically as he backed toward the door. "I wouldn't
touch that snaky-looking thing with a ten-foot pole, let alone my hands. Why on
earth would your uncle send you something like that? Has he sprung his hatch?"
... Jerry was trying to strap a squirming, wriggling something
into the short section of gutter trough, but it kept slithering through his rubber
gloves ... from a story that appeared in the
1956, edition of a storage battery house organ called Exide Topics that my uncle
sent me. What I want to do right now is to double-check on some of the statements
in that story."
"Certainly not. This is not just an ordinary eel. In fact, it's not really an
eel at all. Strictly speaking, it's an electric fish . My uncle says if I'm going
to be an electronics engineer I should know about all forms of electricity; and
electric fishes have been stirring electrons for thousands of years. Pictures of
them appear in Egyptian tombs and they are mentioned in Aristotle's Historia Animalium.
In addition to this so-called electric eel, there are five other fishes with shocking
power: the torpedo or electric ray, the electric catfish, the star-gazer, the numb-fish,
and the elephant-snout fish."
"Never mind the lecture, Professor," Carl said impatiently. "Just tell me what
you are trying to do with old Squirmy there."
"I want to strap him in this rubber-lined trough so I can find out something
about the electric charge he emits. The rubber lining will prevent his being short-circuited
by the metal trough. When I get him fastened down, I'll slide these little tin-foil
strips underneath his body at different points to pick off the charge he emits.
Then, by using the 'scope and the VTVM, I'll know if he has a.c. or d.c. wiring
and how much voltage he puts out."
"You mean you don't have any idea what to expect? And are you wearing those rubber
gloves because you don't want to touch the slimy thing or because you're afraid
of being shocked?"
"To answer the last first, I'm wearing them cause I don't want to be shocked.
A full-grown electric eel can put out a jolting five-hundred volts that can stun
a horse or paralyze a man. Since eight feet is about as long as they get, and since
this one is nearly five feet long, I'd guess he was full grown. He acts fully charged,
too. An adult eel that puts out only three hundred volts is either sick or simply
not letting himself go. Even a baby eel can deliver around 120 volts - as much voltage
as there is in the a.c. house line."
"How do you know all this? You been boning up at the library?"
"Looks like you've got Old Squirmy pretty well trussed up; so let's start double-checking,"
"Okay," Jerry agreed. "First let's see if this eel is a.c. or d.c. According
to the eel experts, the electrical discharge he puts out is a series of rapid direct-current
discharges in the form of short-duration pulses sent out at a rate of about four
hundred per second. But these pulses are of such short duration, about two-thousandths
of a second, that the actual wattage output of an adult electric eel is only about
Then suppose we hook Buster here to a forty-watt bulb," Carl suggested.
"He's no good for lighting bulbs," Jerry explained." Those pulses are too short
to overcome the thermal lag of an incandescent bulb filament. Voltage has to be
applied to such a filament for about one-fiftieth of a second before it begins to
glow, and one of these pulses only lasts about one-tenth that long. But he could
light a neon bulb, and I'm sure he'll make some interesting traces on our 'scope.
I've got an idea about how to check his polarity, too. We'll simply run his output
into this 0.5-microfarad capacitor and let him charge it up with his pulsating voltage.
Then our VTVM connected across it will show his peak voltage and polarity."
As he talked, Jerry slipped one tin-foil electrode beneath the tail of the eel
and another beneath the center of his body. Leads from the electrodes went to the
capacitor, and the VTVM was connected to read the voltage charging this capacitor.
"Three-hundred-and-fifty volts!" Carl announced; "and the way the pointer swings
proves that Old Squirmy's tail is the negative pole of his battery and the front
part of him is the positive pole."
"Watch the meter while I slide this front electrode back and forth," Jerry suggested.
"I want to find where the front end of his generator actually is."
This method soon showed that the maximum voltage, four hundred and eighty volts,
was obtained when the negative electrode was at the eel's tail and the positive
electrode was at a point about a foot back from his head.
"That squares with what the books say," Jerry reported. "According to them, all
of the critter's vital organs are in the front fifth of his body, and the rest is
made up of 'electric tissue.'''
"Whatever that is."
"It's a flabby whitish jelly composed of 92% water. This stuff is organized into
three pairs of electric organs. The eel can use one pair for a major discharge,
one pair for a medium-size whammy, and the third pair for a small shock. Each organ
is made up of smaller units separated by another kind of tissue that acts like the
insulating separators in a storage battery. The electricity is actually produced
in these smaller units. Each one produces about one-tenth of a volt. Somehow, in
some way, the creature is able to connect these units in series to produce the high
voltage discharges. But how he can throw thousands of 'switches' on and off several
hundred times a second in perfect unison is still a mystery."
Jerry connected the leads from the electrodes to the horizontal input terminals
of his 'scope and adjusted the linear sweep until he had two of the voltage spikes
visible on the screen. Since the frequency of the eel's output was irregular, this
pattern was not easy to hold, but a sweep frequency of around 200 cycles per second
displayed two complete pulses. Once again this proved the books were right when
they said that the eel put out about 400 discharges per second.
"For the rest of our experimenting," Jerry mused, "we should have the eel swimming
freely about. Wonder where we can manage that? He's too big for a washtub."
Jerry and Carl looked deep into each other's eyes and saw the same thought. "Okay,"
Jerry said, "but you'll have to go ahead and make sure the coast is clear. Mom is
deathly afraid of this thing, and if she saw us sneaking it into the bathroom, she
would never set foot in there again."
Jerry gathered Old Squirmy, still strapped to. the length of gutter trough, under
his arm and cautiously followed Carl up the basement stairs. Jerry's mother, fortunately,
was busy talking on the telephone and never noticed the boys tiptoeing past the
door on their way to the second floor. Safely inside the bathroom, Carl started
quietly filling the tub with water while Jerry made another trip to the laboratory
for other equipment he wanted. When the tub was two-thirds full, the eel was released
inside it. He seemed to enjoy his freedom and went slithering around on the bottom
of the tub in graceful coils. Jerry separated the earpieces of a pair of headphones
and handed one to Carl.
"Listen!" he said, as he dipped the metal-tipped ends of the headphone cord in
the water. Clearly heard in the phones was a static-like noise. When the eel was
quiet, this noise subsided; but as soon as it started to move, the noise returned.
"Any time he is moving," Jerry explained, "the electric eel gives off a series
of weak discharges. These serve two purposes: first, they warn enemies to keep their
distance; and secondly, they form a kind of radar that enables the eel - which is
virtually blind when it is adult - to seek out its prey."
Wait a minute!" Carl interrupted.
"I'm not so dumb that I don't know a radar system consists of a receiver as well
as a transmitter. I'll admit Old Squirmy has a dan-dan-dandy low-frequency transmitter;
but where's his receiver?"
"He's got one all right, according to the books," Jerry replied. When one eel
in a tank discharges, all the other eels come to the spot, apparently to horn in
on the result. Obviously they know when one of their fellows is trying to stun something
and can judge very nicely where the current is coming from. But now let's see if
we can prove this with the eel-caller I've built up. It's a blocking oscillator
that produces sharp spikes of voltage over a frequency range which is adjustable
from about 500 to 2000 cycles per second. The output of the oscillator drives an
output tube so as to produce pulses of very respectable amplitude across these two
electrodes. Let's place the electrodes in the water at this end of the tub and see
if we can sweet-talk him into coming over."
Carl did as he was told, and Jerry began varying the frequency of the blocking
oscillator. As a certain frequency was reached, the eel on the bottom of the tub
began to stir and swim directly to the electrodes. When they were transferred to
the opposite end of the tub, he immediately moved toward them.
"Old Squirmy's receiving frequency seems to be around 800 cycles per second,"
"Say! That thing really puts the come-hither on him," Carl said enthusiastically.
"We ought to patent it."
"We're a little too late," Jerry told him.
"Eel hunters in South America are already using earphones to locate electric
fish and then are employing eel-callers something like this one to lure them into
their traps. But to get back to his built-in radar, by means of it the electric
eel can move straight toward his prey and can detect a variation of just a few inches.
What's more, he can tell instantly if his prey is moving and can make allowances
for that movement."
You know," Carl mused, "that's all pretty wonderful when you stop to think about
it. Here we think of electricity itself as being quite modern, but that ugly creature
resting there on the bottom of the tub and his ancestors have been using electricity
for thousands of years. What's more, they've been using it in ways that we think
of as being ultra-modern. Since electric eels talk to each other by means of their
electric discharges, we must admit that they are equipped with wireless telephones.
Those same discharges are employed as a compact, efficient, and highly effective
weapon to secure food and to combat enemies. Finally, the lowly eel has been quietly
using radar - which we did not discover until the last war - for countless centuries.
It kind of makes you wonder if man - in spite of all his scientific development
and progress - is so doggone smart as he thinks he is, doesn't it?"
"It certainly does," Jerry agreed, "and I think my uncle had something like that
in mind when he sent me the eel and told me to study it. When we work with electricity
that is man-produced by batteries and generators and so on, we sort of take it for
granted and forget how magic it really is, but when you see electricity being generated
within the living tissue of a live creature such as this, all the wonder and mystery
of it sweeps over you, and you are glad that you intend to make a lifetime study
Posted April 19, 2022
(updated from original post on 7/15/2016)
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."