Coherer
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The coherer was a primitive form of radio signal detector used in the first radio receivers during the wireless telegraphy era at the beginning of the 20th century. Its use in radio was based on the 1
Marconi's 1896 coherer receiver, at the Oxford Museum of the History of Science, UK. The coherer is on right, with the decoherer mechanism behind it. The relay is in the cylindrical metal container (center) to shield the coherer from the RF noise from its contacts.
The circuit of a coherer receiver, that recorded the received code on a Morse paper tape recorder.
A radio receiver circuit using a coherer detector (C). The "tapper" (decoherer) is not shown.
A coherer with electromagnet-operated "tapper" (decoherer), built by early radio researcher Emile Guarini around 1904.
Édouard Branly
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Édouard Eugène Désiré Branly was a French physicist and inventor known for his early involvement in wireless telegraphy and his invention of the coherer in 1890.
Plaque at the Musée Édouard Branly on rue d'Assas in Paris
Cover of "La télégraphie sans fil", 1922
Original Branly tube (no. 78) for radiodetection