Electrolytic detector
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An electrolytic detector, or liquid barretter, is a type of detector used in early radio receivers. It was first used by Canadian radio researcher Reginald Fessenden in 1903, and used until about 1913
Electrolytic detector, consisting of a metal cup with nitric acid and a fine platinum wire with the tip dipping in the acid.
Fessenden barretter
Electroldetc
Crystal detector
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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
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 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 capacitance of the antenna to form the tuned circuit with the coil.
Galena cat whisker detector from a 1920s crystal radio