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H. J. Round
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Captain Henry Joseph Round was an English engineer and one of the early pioneers of radio. He was the first to report the observation of electroluminescence from a solid state diode, leading to the di
Henry Joseph Round, c. 1920
Henry Joseph Round, c. 1920
Recreation of the 1907 experiment by H. J. Round on the observation of electroluminescence from a point contact with a carborundum (silicon carbide) c
Recreation of the 1907 experiment by H. J. Round on the observation of electroluminescence from a point contact with a carborundum (silicon carbide) crystal
Crystal detector
Videos
A crystal detector is an electronic component used in some early 20th century radio receivers. It consists of a piece of crystalline mineral that rectifies an alternating current radio signal. It was
H. J. Round
…He patented the first design for an indirectly heated cathode, the type of cathode widely used in vacuum tubes today. In some later experiments with cat's whisker detectors using a variety of substances, he passed current through them and noticed that some gave off light – the first known report of the effect of the…
Galena cat whisker detector used in early crystal radio
Galena cat whisker detector used in early crystal radio
Precision crystal detector with iron pyrite crystal, used in commercial wireless stations, 1914. The crystal is inside the metal capsule under the ver
Precision crystal detector with iron pyrite crystal, used in commercial wireless stations, 1914. The crystal is inside the metal capsule under the vertical needle (right). The leaf springs and thumbscrew allow fine adjustment of the pressure of the needle on the crystal.
Pictorial diagram from 1922 showing the circuit of a cat whisker crystal radio. This common circuit did not use a tuning capacitor, but used the capac
Pictorial diagram from 1922 showing the circuit of a cat whisker crystal radio. This common circuit did not use a tuning capacitor, but used the capacitance of the antenna to form the tuned circuit with the coil.
Galena cat whisker detector from a 1920s crystal radio
Galena cat whisker detector from a 1920s crystal radio