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
Arthur Williams (electrical engineer) Arthur Williams (electrical engineer) Arthur Williams (August 14, 1868 – April 14, 1937) was an American electrical engineer, executive at the New York Edison Company, Federal Food Administrator of the City of New York, and first president of The National Association of Corporation Schools in 1913. Williams was born in Norfolk, Virginia in 1868, the son of Rev. Christopher S. and Hannah Sanford (Rogers) Williams. He was educated in the public and private schools of Hartford, Conn., and New York City. At the age of sixteen, in 1882, he began his business career with an electrical contractor. He remained in