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In this way, he quickly assembled a 700-alarm network, which his father then copied in New York. [8] In 1878, Holmes became the president of the newly established Bell Phone Company. While he sold his interests two years later for US$100,000, [9] he kept his rights to use the company phone lines for his alarm system. [8]
John Hays Hammond Jr. and Sr., 1922. John Hays Hammond Jr. (April 13, 1888 – February 12, 1965) was an American inventor known as "The Father of Radio Control".Hammond's pioneering developments in electronic remote control are the foundation for all modern radio remote control devices, including modern missile guidance systems, unmanned aerial vehicles (UAVs), and the unmanned combat aerial ...
In Popov's lightning detector the coherer (C) was connected to an antenna (A), and to a separate circuit with a relay (R) and battery (V) which operated an electric bell (B). The radio noise generated by a lightning strike turned on the coherer, the current from the battery was applied to the relay, closing its contacts, which applied current ...
Trevor Graham Baylis CBE (13 May 1937 – 5 March 2018) was an English inventor best known for the wind-up radio.The radio, instead of relying on batteries or external electrical source, is powered by the user winding a crank.
Greenleaf Whittier Pickard (February 14, 1877 – January 8, 1956) was an American electrical engineer and inventor.. While not the earliest discoverer of the rectifying properties of contact between certain solid materials, he was largely responsible and most famous for the development of the crystal detector, the earliest type of diode detector. [1]
The most common type of receiver before vacuum tubes was the crystal set, although some early radios used some type of amplification through electric current or battery. Inventions of the triode amplifier, motor-generator, and detector enabled audio radio.
A galena cat's whisker detector from a 1920s crystal radio. Crystal detector (cat's whisker detector) - invented around 1904–1906 by Henry H. C. Dunwoody and Greenleaf Whittier Pickard, based on Karl Ferdinand Braun's 1874 discovery of "asymmetrical conduction" in crystals, these were the most successful and widely used detectors before the ...
An unusual example were his experiments in using brain tissue to detect radio waves. [6] [7] [8] The first radio receivers prior to 1904 used a primitive device called a coherer to detect the radio waves. The poor performance of the coherer led to much research to find a better radio wave detector.