John Ambrose Fleming

John Ambrose Fleming (1849–1945) was a British electrical engineer and physicist who invented the thermionic two-electrode valve, an early radio detector and rectifier.

Thomas Edison: Thomas Edison was an American inventor and businessman who developed the incandescent lamp and many electrical devices. Fleming observed the one-way current effect in an Edison lamp, an observation that led to his valve.
Thermionic emission: Thermionic emission is the release of electrons from a heated material into surrounding space. The heated cathode supplies the electrons that make the Fleming valve conduct.
Wireless telegraphy: Wireless telegraphy is the transmission of telegraph signals by electromagnetic waves rather than wires. Fleming designed his valve to detect the weak signals used in wireless telegraphy.
Audion: The Audion was Lee de Forest’s three-electrode vacuum tube, capable of amplifying electrical signals. Its control grid extended the Fleming valve’s diode action into amplification.
Guglielmo Marconi: Guglielmo Marconi was an Italian inventor and entrepreneur who developed practical wireless telegraphy systems. Marconi employed Fleming as a consultant, prompting the valve’s development for radio detection.
Vacuum tube: A vacuum tube is an electronic device that controls electric current through electrodes in an evacuated enclosure. The Fleming valve is an early, simple member of this broader device family.
Radio receiver: A radio receiver captures electromagnetic signals and converts them into information or sound. The valve improved the detection of radio-frequency signals in early receivers.
Radio engineering: Radio engineering applies electrical and electromagnetic principles to transmitting and receiving radio signals. Fleming’s valve became one of the early components around which this discipline developed.
Lee de Forest: Lee de Forest was an American inventor who developed the audion, a three-electrode vacuum tube. His added control grid made the audion capable of amplification beyond Fleming’s two-electrode valve.
Rectifier: A rectifier is a device that converts alternating current into unidirectional current. The valve’s one-way conduction made it a vacuum-tube rectifier.

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