SHEILA TERRY / SCIENCE PHOTO LIBRARY SHEILA TERRY / SCIENCE PHOTO LIBRARY
Lee De Forest (1873-1961), American radio pioneer, holding the triode valve, or Audion tube, that he invented. De Forest studied at Yale, gaining his doctorate with a thesis on radio waves. In 1907 he patented the Audion tube. This was an adaptation of a diode, with a third electrode between the cathode and anode. The Audion was used as a detector of radio signals, an amplifier of audio and an oscillator for transmitting. In 1913, AT&T installed audions to boost voice signals as they crossed the US continent and not long after, they were being used in radios. De Forest is considered to be one of the fathers of the electronic age.
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