Valve amplifier thermionic valves. The simplest valve was invented by John Ambrose Fleming while working for the Marconi Company in London in 1904 and named the diode, as it had two electrodes. The diode conducted electricity in one direction only and was used as a radio detector and a rectifier. In 1906 Lee De Forest added a third electrode and invented the first electronic amplifying device, the triode, which he named the "Audion". This additional "control grid" modulates the current that flows between cathode and anode. The relationship between current flow and plate and grid voltage is often represented as a series
William McLellan (American electrical engineer) spent much of his career as an engineer in Caltech's Astronomy department, remaining a consultant there for the rest of his life. He died in 2011 in Pasadena. William McLellan (American electrical engineer) William Howard McLellan (December 1, 1924 – September 30, 2011) was an American electrical engineer, who achieved some fame in 1960 by succeeding at an engineering challenge set by Nobel Prize-winning physicist Richard Feynman. McLellan was born in Casper, Wyoming, grew up in Orland, California, and fought in the Canadian Army in the Second World War. He met his wife Patricia Price in England during the war,