Science: Electronics in Control

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Mechanism of Revolution. Actual father of electronics is Lee De Forest.* who evolved the first modern electron tube in 1906. But the grandfather was Thomas Alva Edison. He noticed in 1883 that the hot wire in his new light bulb gave off electricity, but he could neither understand nor use the effect. In 1904 Sir J. Ambrose Fleming sealed a separate metal plate through the glass into an Edison light bulb, was able to draw current from the plate. De Forest added the grid. How many electrons from the filament reach the plate, and how fast, depends on the intervening grid which is acted upon by incoming electric stimuli.

The grid is the sense organ of the tube. To it is attached an antenna if the tube is to be used for radio reception, a microphone if it is to amplify sound, or an electric eye if it is to respond to light signals. Changes of voltage on the grid change the current from filament to plate. In each case the extremely faint stimuli received by the grid are amplified to hundreds of times their original strength. By using several tubes, with the plate of one connected to the grid of the next, the amplification can be multiplied to thousands or millions.

The plate is attached to the outgoing circuit leading to a radio loudspeaker, or public-address system, or telephone, or a magnet which controls an electric switch if the tube is to set a machine in motion. In the illustration, the electric eye is immune to the correct color of healthy oranges. When it "sees" a defective orange it sends a slight current to the grid. This steps up the current from filament to plate, causes a magnet to operate an ejector device which instantly sends that orange out of the packing line.

Great new streamscapes of the electronic world may be visible at the war's end:

> Detectors on ocean vessels to make visible other ships, icebergs, shores, through night and thick fog.

> Very short radio waves to multiply available radio channels, possibly by many thousands, making possible wide use of radiotelephones by truck fleets, construction gangs, large-scale industrial and mining operations.

> Television to project pictures on screens 18 by 24 feet, in full color (already possible). Programs are now picked up at Schenectady from Manhattan, 135 miles away, forecasting national network programs by relay stations.

* Often and deceptively called the "radio" tube (which suggests only a fraction of its uses). * Sharp-eyed, white-fringed Lee De Forest, 69, inventor of hundreds of subsequent electronic devices, maker and loser of several fortunes, now lives in a huge hillside home at Hollywood, drives daily to his unimpressive laboratory on Wilshire Boulevard, is putting into production an altimeter which indicates the height of a plane above the actual ground beneath instead of sea level. He also manufactures diathermy equipment, to which he credits his own excellent health. Last July in a single week he climbed both Mt. Whitney (highest in the U.S.) and Mt. Langley.

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