DIODES was discovered by FREDERICK GUTHREI in 1873

FREDERICK GUTHREI in 1873

Although the crystal diode was popularised before the thermionic diode, thermionic and solid state diodes developed in parallel. The principle of operation of thermionic diodes was discovered by Frederick Guthrie in 1873.[1] The principle of operation of crystal diodes was discovered in 1874 by the German scientist, Karl Ferdinand Braun.[2]

Thermionic diode principles were rediscovered by Thomas Edison on February 13, 1880 and he was awarded a patent in 1883 (U.S. Patent 307,031 ), but developed the idea no further. Braun patented the crystal rectifier in 1899 [1]. Brauns discovery was further developed by Sir Jagdish Bose into a useful device for radio detection.

The first radio receiver using a crystal diode was built around 1900 by Greenleaf Whittier Pickard. The first thermionic diode was patented in Britain by John Ambrose Fleming (scientific adviser to the Marconi Company and former Edison employee[2]) on November 16, 1904 (U.S. Patent 803,684 in November 1905). Pickard re ...more