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Summary
| Description |
English: Early
Fleming valves. Shows several different designs used by Fleming. 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. It consisted of an evacuated glass bulb containing two
electrodes: a
cathode in the form of a tantalum wire
filament, and a
anode (
plate) consisting of a sheet metal cylinder surrounding the filament. A separate current through the filament heated it red-hot, releasing electrons into the vacuum of the tube. The AC voltage to be rectified was applied between anode and filament. When the anode is positive, the electrons from the filament are attracted to it and a current flows through the tube. When the anode is negative the electrons are not attracted so no current flows. |
| Date | between 1904 and 1919 |
| Source | Downloaded July 18, 2013 from John Ambrose Fleming (1919) The Thermionic Valve and its Developments in Radiotelegraphy and Telephony, The Wireless Press, London, p. 53, fig. 28A on Google Books |
| Author | John Ambrose Fleming |
Licensing
 |
This media file is in the
public domain in the
United States. This applies to U.S. works where the copyright has expired, often because its first
publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See
this page for further explanation.
|
 |
 |
This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the
rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See
Wikipedia:Public domain and
Wikipedia:Copyrights for more details.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 18:31, 21 July 2013 |
| 1,218 × 543 (146 KB) | Chetvorno | User created page with UploadWizard |
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