Édouard Branly
| Édouard Eugène Désiré Branly | |
|---|---|
,_Physicist_(2536834552).jpg) |
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| Born |
23 November 1844 Amiens |
| Died | 24 March 1940 (aged 95) Paris |
Édouard Eugène Désiré Branly (23 October 1844 – 24 March 1940) was a French inventor, physicist and professor at the Institut Catholique de Paris. He is primarily known for his early involvement in wireless telegraphy and his invention of the Branly coherer around 1890.
He was born on 23 October 1844. Édouard Branly died in 1940. His funeral was at the Notre Dame cathedral in Paris and was attended by the President of France, Albert Lebrun. He was interred in Père Lachaise Cemetery in Paris.
's experiments with tubes of metal filings, as reported in "Il Nuovo Cimento" in 1884, led to the development of the first radio wave detector, the coherer, by Branly some years later. It was the first widely used detector for radio communication. This consisted of iron filings contained in an insulating tube with two electrodes that will conduct an electric current under the action of an applied electrical signal. The operation of the coherer is based upon the large resistance offered to the passage of electric current by loose metal filings, which decreases when direct current or alternating current is applied between the terminals of the coherer at a predetermined voltage. The mechanism is based on the thin layers of oxide covering all the filings, which is highly resistive. The oxide layers are broken down when a voltage is applied of the right magnitude, causing the coherer to "latch" into its low-resistance state until the voltage is removed and the coherer is physically tapped.
The coherer became the basis for radio reception, and remained in widespread use for about ten years, until about 1907. British radio pioneer Oliver Lodge made the coherer into a practical receiver by adding a "decoherer" which tapped the coherer after each reception to dislodge clumped filings, thus restoring the device's sensitivity. It was further developed by Guglielmo Marconi, then replaced about 1907 by crystal detectors.
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