Beyond the Transistor
July 1963 Radio-Electronics

July 1963 Radio-Electronics

July 1963 Radio-Electronics Cover - RF Cafe[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.

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 ...

"Beyond the Transistor, July 1963 Radio-Electronics - RF CafeBy 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.