History of electronic engineering on to develop the first practical and widely used radio wave based communication system. In 1904, John Ambrose Fleming, the first professor of electrical Engineering at University College London, invented the first radio tube, the diode. Then, in 1906, Robert von Lieben and Lee De Forest independently developed the amplifier tube, called the triode. Electronics is often considered to have begun with the invention of the triode. Within 10 years, the device was used in radio transmitters and receivers as well as systems for long distance telephone calls. The invention of the triode amplifier, generator, and detector made audio communication
Alan Blumlein is effectively connected as a triode, and if the tap was at the supply end, as a pure pentode. Blumlein discovered that if the tap was placed at a distance 15–20% down from the supply end of the output transformer, the tube or valve would combine the positive features of both the triode and the pentode design. Blumlein may or may not have invented the long-tailed pair, but his name is on the first patent (1936). The long-tailed pair is a form of differential amplifier that has been popular since the days of the vacuum tube (valve). It is now