born Aug. 26, 1873, Council Bluffs, Iowa, U.S.
died June 30, 1961, Hollywood, Calif.
U.S. inventor.
He had invented many gadgets by age 13, including a working silverplating apparatus. After earning a Ph.D. from Yale University, he founded the De Forest Wireless Telegraph Co. (1902) and the De Forest Radio Telephone Co. (1907). In 1907 he patented the Audion vacuum tube detector, which allowed more sensitive reception of radio signals such as his live broadcast of a performance by Enrico Caruso (1910). He developed a sound-on-film optical-recording system called Phonofilm and demonstrated it in theatres (1923–27). A poor businessman who was twice defrauded by business partners, he eventually sold his patents at low prices to such firms as American Telephone & Telegraph Co., which profited highly from their commercial development. Though embittered, he was widely honoured as the father of radio and the grandfather of television.