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File:Edwin Armstrong at blackboard.jpg

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Description
English: American electrical engineer and inventor Edwin H. Armstrong in 1922. Armstrong is one of the most prolific inventors in the history of radio. He invented the regenerative circuit (vacuum tube feedback oscillator), the superregenerative receiver, the superheterodyne receiver, and frequency modulation (FM) radio transmission. This was probably taken at the June 28, 1922 meeting of the Radio Club of America in room 306, Havemeyer Hall, Columbia University, New York, at which Armstrong demonstrated the superregenerative receiver. his prototype is partially visible on the right.
Date
Source Downloaded April 23, 2013 from Allen L. Benson, Armstrong of the Radio-Phone in Hearst's International, International Magazine Co., New York, Vol. 42, No. 3, November 1922, p. 90 on Google Books
Author Unknown authorUnknown author

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Public domain
This work is in the public domain in the United States because it was published (or registered with the U.S. Copyright Office) before January 1, 1929.

Public domain works must be out of copyright in both the United States and in the source country of the work in order to be hosted on the Commons. If the work is not a U.S. work, the file must have an additional copyright tag indicating the copyright status in the source country.
Note: This tag should not be used for sound recordings.PD-1923Public domain in the United States//commons.wikimedia.org/wiki/File:Edwin_Armstrong_at_blackboard.jpg

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Date/TimeThumbnailDimensionsUserComment
current18:06, 3 May 2021Thumbnail for version as of 18:06, 3 May 2021776 × 772 (294 KB)MaterialscientistFFT
11:29, 23 April 2013Thumbnail for version as of 11:29, 23 April 2013784 × 783 (121 KB)ChetvornoUser created page with UploadWizard

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