Triode were invented, Philipp Lenard used the principle of grid control while conducting photoelectric experiments in 1902. The first vacuum tube used in radio was the thermionic diode or Fleming valve, invented by John Ambrose Fleming in 1904 as a detector for radio receivers. It was an evacuated glass bulb containing two electrodes, a heated filament and a plate (anode). Triodes came about in 1906 when American engineer Lee De Forest and Austrian physicist Robert von Lieben independently patented tubes that added a third electrode, a grid, between the filament and plate to control current. Von Lieben's partially-evacuated three-element tube, patented
Jim McDonald (electrical engineer) Jim McDonald (electrical engineer) Sir James McDonald FREng FRSE FInstP FIET is a British educator, serving as Principal and Vice-Chancellor of the University of Strathclyde since 2009. He is also a visiting professor at NYU Tandon School of Engineering. After seven years of work within the UK Electricity Supply Industry, McDonald joined Strathclyde University in 1984 and became Professor of Electrical Power Systems in 1993. In 2001 he was invited to deliver the MacMillan Memorial Lecture to the Institution of Engineers and Shipbuilders in Scotland. He chose the subject "Electric Propulsion in Marine Applications: An Electrical Engineer's Viewpoint". In 2006