Radio receiver crude triode, was invented in 1906 by Lee De Forest as a more sensitive detector for radio receivers, by adding a third electrode to the thermionic diode detector, the Fleming valve. It was not widely used until its amplifying ability was recognized around 1912. The first tube receivers, invented by De Forest and built by hobbyists until the mid 1920s, used a single Audion which functioned as a grid-leak detector which both rectified and amplified the radio signal. There was uncertainty about the operating principle of the Audion until Edwin Armstrong explained both its amplifying and demodulating functions in a
David Davies (electrical engineer) David Davies (electrical engineer) Sir David Evan Naunton Davies , known as Den Davies or David "DEN" Davies, (born 1935) is a British electrical engineer and educator. He was knighted for services to science in 1994. 1985-1988: Head of the Department of Electronic and Electrical Engineering at University College London (UCL), and holder of the Pender Chair, having already been lecturing there, in "Communications Systems", for many years prior to that. 1986-1988: Vice-Provost of University College London 1988-1993: Vice Chancellor of Loughborough University 1993–1999: Chief Scientific Adviser for the Ministry of Defence 1994-1995: President of the Institution of Electrical Engineers