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File:Fleming valves.jpg

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Summary

Description
English: The first prototype Fleming valves. The Fleming valve, invented in 1904 by John Ambrose Fleming, as a detector for radio waves in early radio receivers, was the first thermionic diode and the first vacuum tube. The basic configuration consisted of an evacuated glass bulb containing two electrodes: a cathode in the form of a wire filament heated white-hot by a current through it, and a metal anode usually consisting of a flat plate. Since only the filament produces electrons, the current of electrons through the tube can only pass in one direction, from filament to anode. In these early tubes, the filament is the vertical loop of wire, while the anode has various shapes, such as the coil of wire in the lefthand tube. The caption says: "Photograph of the oscillation valves first employed by Dr. J. A. Fleming, FRS, in October 1904, for the rectification of high-frequency electric oscillations as used in wireless telegraphy"
Date between 1904 and 1919
date QS:P,+1950-00-00T00:00:00Z/7,P1319,+1904-00-00T00:00:00Z/9,P1326,+1919-00-00T00:00:00Z/9
Source Downloaded July 18, 2013 from John Ambrose Fleming (1919) The Thermionic Valve and its Developments in Radiotelegraphy and Telephony, The Wireless Press, London, frontispiece on Google Books
Author John Ambrose Fleming

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Public domain
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United States
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Captions

Photograph of the oscillation valves first employed by Dr. J. A. Fleming, FRS, in October 1904, for the rectification of high-frequency electric oscillations as used in wireless telegraphy.

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Date/TimeThumbnailDimensionsUserComment
current07:15, 19 July 2013Thumbnail for version as of 07:15, 19 July 20131,956 × 1,204 (621 KB)ChetvornoUser created page with UploadWizard

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