Blondel_coherer_and_Guarini_decoherer.jpg
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Summary
Description Blondel coherer and Guarini decoherer.jpg |
English:
A
coherer
, a crude radio detector used in the first radio receivers from about 1895 to 1906 during the
wireless telegraphy
era. This example was built by radio researcher Emile Guarini Foresio. It is a glass tube
(right)
containing metal powder between two electrodes. When a radio signal is applied between the electrodes, the metal powder coheres (clumps together) causing the tube to conduct electricity. The coherer is attached to a DC circuit
(not shown)
which makes a mark on a paper tape to record the
Morse code
radio message. Because the coherer remained in its conducting state after the radio wave stopped, the device includes a "decoherer" or "tapper"
(left)
which uses an electromagnet-activated arm to tap the coherer, agitating the powder, to return the device to its nonconducting state in preparation to receive another radio signal.
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Date | |
Source | Downloaded 2010-03-04 from A. Frederick Collins (1904) "The Metamorphosis of Wireless Telegraph Apparatus" in The Engineering Magazine , Vol. 27, No.4 (June 1904) p.376, fig. 24 on Google Books |
Author | Archie Frederick Collins |
Permission
( Reusing this file ) |
Public domain in USA - Published in USA prior to 1923 |
Licensing
Public domain Public domain false false |
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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This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the
rule of the shorter term
for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See
Wikipedia:Public domain
and
Wikipedia:Copyrights
for more details.
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Annotations
InfoField
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This image is annotated: View the annotations at Commons |
442
38
199
53
663
707
Coherer