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Marconi's wireless magnetic detector (London) The magnetic detector or Marconi magnetic detector, sometimes called the "Maggie", was an early radio wave detector used in some of the first radio receivers to receive Morse code messages during the wireless telegraphy era around the turn of the 20th century.
The device that performed this function in the receiver circuit was called a detector. [1] A variety of different detector devices, such as the coherer, electrolytic detector, magnetic detector and the crystal detector, were used during the wireless telegraphy era until superseded by vacuum tube technology.
Headphones appeared in the emerging field of wireless telegraphy, which was the beginning stage of radio broadcasting. Some early wireless telegraph developers chose to use the telephone receiver's speaker as the detector for the electrical signal of the wireless receiving circuit. [17]
The circuit of a coherer receiver, that recorded the received code on a Morse paper tape recorder. Unlike modern AM radio stations that transmit a continuous radio frequency, whose amplitude (power) is modulated by an audio signal, the first radio transmitters transmitted information by wireless telegraphy (radiotelegraphy), the transmitter was turned on and off (on-off keying) to produce ...
Greenleaf Whittier Pickard (February 14, 1877 – January 8, 1956) was an American electrical engineer and inventor. He was largely responsible and most famous for the development of the crystal detector, the earliest type of diode detector, although he was not the earliest discoverer of the rectifying properties of contact between certain solid materials. [1]
Type 'C' Form 'A' twin detector crystal radio set, manufactured by British Thomson Houston Ltd. in 1924, kept at the Museum of the radio - Monteceneri (Switzerland) Early radio telegraphy used spark gap and arc transmitters as well as high-frequency alternators running at radio frequencies. The coherer was the first means of detecting a radio ...