Radioconducteur_07.jpg
Size of this preview:
600 × 600 pixels
.
Other resolutions:
240 × 240 pixels
|
480 × 480 pixels
|
768 × 768 pixels
|
1,024 × 1,024 pixels
|
1,626 × 1,626 pixels
.
Summary
Description Radioconducteur 07.jpg |
Français :
Radioconducteur à trepied
English:
A tripod
coherer
, an experimental radio wave detector invented in 1902 by French radio researcher Édouard Branly . Coherers were used in the first radio receivers around 1900. In this device the radio signal from an antenna was applied between the metal 'tripod' and the bottom plate. Although most coherers functioned as "switches", turning on a DC current from a battery to record the radio signal, the tripod coherer may have been one of the first
rectifying
(diode) detectors, because Branly reported it could produce a DC signal without a battery. The imperfect contact between the rounded metal legs, which had a slight semiconducting coating of iron oxide on them, and the iron plate at the bottom of the glass bulb, functioned as a crude
PN junction
, rectifying the radio waves. The rectified signal was applied to an earphone connected across the plates, and the "dots" and "dashes" of the Morse code transmitter could be heard. This made it one of the first semiconductor devices, a predecessor to the
crystal detector
and the
semiconductor diode
(See E. Branly (1902) "A Sensitive Coherer",
Comptes Rendes
, Vol. 134, p. 1197. Information from
John Ambrose Fleming (1919)
The Principles of Electric Wave Telegraphy and Telephony, 4th Ed.
, London, Longmans, Green & Co. p.374
)
|
Source | Own work |
Author | BernieBLK |
Licensing
I, the copyright holder of this work, hereby publish it under the following licenses:
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License , Version 1.2 or any later version published by the Free Software Foundation ; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License . http://www.gnu.org/copyleft/fdl.html GFDL GNU Free Documentation License true true |
This file is licensed under the
Creative Commons
Attribution-Share Alike
3.0 Unported
,
2.5 Generic
,
2.0 Generic
and
1.0 Generic
license.
-
You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
-
Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
- share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
You may select the license of your choice.