File:Cartridge carborundum detector.jpg
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Summary[edit]
| Description |
English: A carborundum crystal detector, an early semiconductor diode, used as a radio detector in 1920s radios. Invented in 1906 by Henry Harrison Chase Dunwoody, It consists of a piece of carborundum (silicon carbide) attached to one terminal, with a spring-loaded pin making contact with the surface. Since the carborundum detector didn't require the delicate "cat's whisker" contact needed by other cat's whisker detector crystals such as galena, it didn't have to be adjusted before each use and could be made in the form of a sealed cartridge. In addition to crystal radios, this type was also used in some powered vacuum tube radios because it was more sensitive to weak stations than the grid-leak vacuum tube detectors usually used. In use it was usually biased by a DC voltage of 3-4 volts to operate at the most sensitive point of its current-voltage curve. |
| Date | |
| Source | Retrieved July 9, 2014 from Radio in the Home magazine, Henry M. Neely Publishing Co., Philadelphia, Pennsylvania, Vol. 4, No. 11, July 1925 p. 25 on American Radio History website |
| Author | Unknown author |
| Permission (Reusing this file) |
This 1925 issue of Radio in the Home magazine would have the copyright renewed in 1953. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1952, 1953, and 1954 show no renewal entries for Radio in the Home. Therefore the magazine's copyright was not renewed and it is in the public domain. |
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This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs. Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 12:37, 22 August 2014 | | 355 × 102 (6 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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