Branly copper rod coherer

Forfatter/Opretter:

Archie Frederick Collins

Kredit:

Retrieved 12 November 2013 from Archie Frederick Collins 1905 Wireless Telegraphy: It's History, Theory and Practice, McGraw Publishing Co., New York, p. 146, fig. 134 on Google Books

Shortlink:

https://dkwiki.dk/b/4399a

kilde:

Wikimedia Commons

størrelse:

1386 x 1083 Pixel (22052 Bytes)

beskrivelse:

A simple radio wave detector or coherer invented by French scientist Édouard Branly around 1890 and used in some of the first experiments at receiving radio communication. It consists of two copper bars which are roughened and oxidized and laid one over the other, creating a high resistance junction. A dipole radio antenna consisting of two wires were attached to the two bars. The bars were also connected to a DC circuit consisting of a battery and a galvanometer. When a radio signal from a spark gap radio transmitter was received by the antenna and applied to the bars, the resistance of the contact between them dropped to a low level. Electric current from the battery passed through the coherer and was detected by the galvanometer, registering the presence of the radio wave. Before receiving another signal, the device had to be restored to its receptive condition by tapping it, disturbing the junction between the bars to reset it to its previous high resistance state. Branly wrote that the device could be made more sensitive by grinding the top bar into a knife edge and resting it very lightly on the other.

Licens:

Public domain