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July 1963 Radio-Electronics
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
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This "Beyond the
Transistor" article by Hugo Gernsback, which was printed in a 1963 issue of
Radio-Electronics magazine, had as its subject not the transistor in
general, but specifically its potential use as a low noise, high sensitivity
radio frequency signal detector. Mr. Gernsback does a useful historical review
of signal detectors, beginning with Heinrich Hertz's radio detector in 1888,
then progressing through
Edouard Branly's
1892 coherer, Gustave-Auguste Ferrie's and Reginald Fessenden's electrolytic
detector of 1903, then Greenleaf Pickard's crystal detector in 1906. Lee
de Forest's early work on vacuum tubes was directed toward a signal detector,
and ultimately resulted in his Audion amplifier. In 1948, Bell Laboratories'
Shockley, Brattain and Bardeen announced their semiconductor (germanium)
transistor. It was the beginning of Gernsback's desire for an ideal signal
detector / amplifier. The electronics industry has progressed far beyond that
point in the intervening decades.
Beyond the Transistor ... The Ideal Detecting Device Is
Still in the Future ...
 By Hugo Gernsback
It was Heinrich Hertz, the discoverer of electromagnetic (radio) waves, who also
invented the first radio detector in 1888. Curiously enough, this detector was of
the visual variety: A single metal wire loop with two small brass balls fixed less
than a millimeter apart, which at the ends of the wire gave out tiny sparks when
the wire loop was brought into the charged field of the transmitter. The visual
sparks were the first demonstration of the new electromagnetic waves, now known
as radio waves.
Hertz' waves, however, could not be detected outside of the laboratory. Other
scientists took up his work to create more sensitive responders that would detect
such waves over greater distances. Marconi, in 1896, invented his wireless transmitter
and receiver with which signals could be transmitted over the English Channel -
more than 30 miles. As his detector he used the
coherer, first demonstrated by Prof.
Edouard Branly of Paris in 1892 and Popoff of Russia in 1895.
Next came Gen. Gustave-Auguste Ferrie's and Prof. Reginald Fessenden's electrolytic
detector in 1903, far more sensitive than the coherer. This in turn was eclipsed
by the first crystal detector, invented and patented by Dr. Greenleaf W. Pickard
in 1906*.
There was also the unusual man made-crystal detector, the Carborundum, invented
by Gen. H. H. C. Dunwoody in 1906. Quite sensitive and stable, it required a 1.5-volt
battery to function properly. It was a crystalline semiconductor composed of silicon
carbide of a dark-blue-green color.
In 1904, John Ambrose Fleming invented the first two-element diode detector tube
based upon Thomas A. Edison's 1883 "Edison effect."
The great breakthrough in radio detectors occurred in 1906 when Dr. Lee de Forest
invented his Audion, the first three-element vacuum tube. But de Forest's vacuum
tube did not long stay a simple detector; his vacuum tube connected in cascade became
the first true radio amplifier. But not until 1914 did de Forest invent his oscillating
vacuum tube, which also gave the world the radio transmitter and regeneration. Now
radio waves could be detected 12,000 miles away - the distance limit of this planet!
(Indeed, in the 1930's radio amateurs could communicate with the antipodes with
only a small radio rig powered by a few dry cells.)
Still later, de Forest gave the Audion a voice: the modern radio telephone had
been born. And that ushered in radio broadcasting circa 1920.
The triumphant march of the vacuum tube lasted uncontested for more than 40 years.
Good as it was, it had one serious flaw: It required a hot filament or cathode to
generate a steady flow of electrons. It also needed an A and a B battery or electric
supply current to function.
In 1948, Drs. Shockley, Brattain and Bardeen of Bell Laboratories gave the world
their transistor. It required no electrical power to speak of and did everything
the vacuum tube did - and more. Already, thanks to miniaturization, the size of
transistors has shrunk to the almost invisible. Even today excellent radio sets,
the size of a cigarette pack, are commonplace.
Yet progress never stops. While the earth has shrunk to miniature size, galactic
space has not - it never will. True, we already have sent our radio probes 40 million
miles out into interplanetary space towards our nearest planet, Venus, and received
intelligible signals back. But this is a mere beginning. It does not satisfy science.
The great difficulty with vacuum tubes and transistors lies in their inherent
noise. When the incoming signal is weaker than the internal electron noise produced
in the receiver, amplification becomes useless. The more you amplify, the more your
noise increases.
So we come back to where we started: We need far quieter radio-wave detectors
than those known at present.
Radio astronomers are particularly frustrated by our modern detecting and amplifying
gear. They deal not in paltry millions of miles distances, hut in billions of billions
of miles. Thus one of the not too distant objects, the great nebula Andromeda (M31),
is 1,600,000 light-years distant from us. Its natural radio signals intercepted
by our radio astronomers take over 1.5 million years to reach us. To us these signals
are only unintelligible loud hisses.
Yet scientists today know that we are not alone in the universe. Humans are not
the only reasoning and intellectual creatures - it would be ludicrous to think so.
Sooner or later, with more sophisticated radio gear, we will intercept the intelligible
signals for which we are waiting. These may come this year, 100 or 1,000 or 10,000
years hence. When will we be ready to decipher them?
The answer obviously lies in a super-law-noise detecting means. How will it be
made? With our present-day knowledge, we can only guess.
Perhaps we require a cryogenic (cold near absolute zero) noncurrent-carrying
device as a detector. Carrying no electric current inherently, it could not amplify
internal electronic noises, only the incoming, fantastically weak micro-signals.
An impossibility? Not necessarily. We have solved more difficult problems in the
past.
* Also in 1906 Dr. L. W. Austin patented a silicon detector (tellurium in contact
with aluminum or silicon).
In 1907 Dr. Pickard invented the zincite detector, in 1908 the bornite and molyybdenite
detectors, and in 1909 the Perikon (chalcopyrite) detector.
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