History of Diodes
While thermionic diodes were previously popularized by crystal diodes (solid state), thermionic and solid state diodes were developed in parallel.
The basic principles of the operation of the thermionic diode were discovered by Frederick Guthrie in 1873. Guthrie discovered that a positively charged electroscope brought a white-hot metal close to (but without actual contact with) ground The film can be discharged from the hospital. The same does not apply to a negatively charged electroscope, which indicates that current flows in only one direction.
Principle was independently rediscovered by Thomas Edison on February 13, 1880. At the time, Edison was conducting research into why the filament of his carbon filament light bulbs almost always burned at the actively connected terminals. He had a special light bulb made of a glass cover sealed with a metal plate, and he was able to confirm that an invisible electric current could be drawn from the glowing filament through the evacuated metal plate, but only when the plate was connected to a positive power source.
Edison invented a circuit with a modified light bulb that more or less replaced the resistor of a DC voltmeter, for which he was granted a patent in 1883 (U.S. Patent 307031). There was no apparent actual use of such a device, and the patent application was most likely just a precautionary measure in case someone else didn't find a use for the so-called "Edison Effect".
About 20 years later, John Fleming (scientific consultant to the Marconi Corporation and former Edison employee) realized that the Edison effect could serve as an accurate radio detector. Fleming's patent, dated 16 November 1904 (received by US Patent 803684 in November 1905), was the first true thermionic diode in Britain.
The operating principle of the crystal diode was discovered in 1874 by German scientist Karl Ferdinand Braun. Braun patented the crystal rectifier in 1899. Jagdish Chandra Braun's discovery was further developed into a useful radio detection device.
Greenleaf Whittier Pickard built the first practical radio receiver, using crystal diodes. Pickard patented a silicon crystal detector on November 20, 1906 (US Patent 836531).
Other experimenters have tried a variety of minerals and other substances, although by far the most popular lead sulfide mineral is galena.
While performing slightly better, other substances offered the advantage of galena being cheap and readily available, and cheaply fixed germanium diodes in homemade "crystal sleeves" were almost exclusively used until the advent of the 1950s. use.
At the time of their invention, this device was called a rectifier. In 1919, William Henry Eccles coined the term diode from the Greek root diameter meaning "through", and ODE meaning "path".