File:Edwin Armstrong at blackboard.jpg
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Summary
| 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 author |
Licensing
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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. |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 18:06, 3 May 2021 | | 776 × 772 (294 KB) | Materialscientist | FFT |
| 11:29, 23 April 2013 |  | 784 × 783 (121 KB) | Chetvorno | User created page with UploadWizard |
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