The Fleming Valve

While at University College London in the 1880s, British scientist and Professor John Ambrose Fleming investigated the "Edison effect," which, discovered in 1883, is electrical conduction within an evacuated glass bulb, from an incandescent filament, to a metal plate. In 1904 his prototype rectified high-frequency oscillations and thus detected wireless signals. Fleming patented the device, ultimately named the "Fleming valve," "oscillation valve," or "Fleming diode."