File:Fessenden alternator.jpg
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Summary[edit]
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English: A prototype of the Alexanderson alternator radio transmitter, a radio frequency alternator built by General Electric Co. and designed by Canadian engineer Reginald Fessenden, installed at his wireless station at Brant Rock, Massachusetts in 1906. Fessenden used it on 24 December 1906 to make one of the first historic AM (sound) transmissions by radio, a program of gramophone Christmas music and of him playing the violin, which is considered one of the first radio entertainment broadcasts in history.
Alterations to image: Removed aliasing artifacts (crosshatching) introduced during scanning of the original halftone photo, using Gimp FFT filter.The device functioned as an AC generator which spun at a very high speed, producing radio frequency current. It produced a frequency of 80,000 Hz with the rotor turning at 20,000 RPM. The rotor is at center, at right is the electric motor that turned it by a system of belts, center foreground is the spiral tank inductor, the box at right contains the capacitors which together make the transmitter's tuned circuit. Rotating radio transmitters like the Alexanderson alternator were a short-lived continuous wave technology that were used to transmit voice before vacuum tube transmitters made them obsolete in the 1920s. |
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| Source | Downloaded 21 September 2013 from Ernst Walter Rühmer 1908 Wireless Telephony in Theory and Practice, D. Van Nostrand Co., New York, translated by James Erskine-Murray, p. 139, fig. 105A on Google Books |
| Author | Ernst Walter Rühmer |
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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.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 05:18, 22 September 2013 | | 1,510 × 1,143 (246 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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