File:Hughes carbon microphone.png
Hughes_carbon_microphone.png (721 × 212 pixels, file size: 27 KB, MIME type: image/png)
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Summary
editDescriptionHughes carbon microphone.png |
English: Adjustable carbon rod microphone invented by David Edwards Hughes around 1878. It consists of a horizontal carbon rod (M) balanced on a fulcrum support (A) making contact lightly with a carbon block (C). Sound vibrations made the rod vibrate, putting varying pressure on the carbon granules at the contact point, causing variation in the resistance. When the two wires were connected in a circuit with a telephone receiver and a battery, the sounds could be heard from the receiver. The pressure at the contact point could be precisely adjusted by the thumbwheel and spring (S). Edwards did not invent the microphone but experimented with a wide range of "microphonic" electrical contacts. With another type of contact he discovered he could detect electromagnetic waves from a spark, thus inventing a type of coherer. |
Date | |
Source | Retrieved April 8, 2015 from Thomas Gray, "Telephone", Encyclopaedia Britannica, 9th Edition, Charles Scribner's Sons, New York, 1888, Vol. 23, p. 132, fig. 12 on Google Books |
Author | Thomas Gray |
Licensing
editPublic domainPublic domainfalsefalse |
This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 70 years or fewer. 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. | |
This file has been identified as being free of known restrictions under copyright law, including all related and neighboring rights. |
https://creativecommons.org/publicdomain/mark/1.0/PDMCreative Commons Public Domain Mark 1.0falsefalse
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current | 18:55, 9 April 2015 | 721 × 212 (27 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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Horizontal resolution | 28.35 dpc |
Vertical resolution | 28.35 dpc |
File change date and time | 02:21, 9 April 2015 |