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English: 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 twentieth century. It consisted of a tube or capsule containing two electrodes spaced a small distance apart, with metal filings in the space between them. It was a key enabling technology for radio, and was the first device used to detect radio signals in practical spark gap transmitter wireless telegraphy. Its operation is based upon the large resistance offered to the passage of electric current by loose metal filings being decreased under the influence of radio frequency alternating current. The coherer became the basis for radio reception around 1900, and remained in widespread use for about ten years. It saw commercial use again briefly in the mid 20th century in a few primitive radio-controlled toys that used spark-gap transmitter controllers. (→Coherer)
English: Coherer


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Media in category "Coherers"

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