Elmer T. Cunningham registers his trademark AudioTron on March 30, 1916 but sells AudioTron tubes since August 1915 with first advertisements in November 1915. The AudioTron (also written as Audio Tron or Audiotron) was made in Oakland, California. In for about three months in 1916/17 Cunningham sold also these double ended tubes with two filaments under the brand Amplitron. By April 6, 1917, the dismantling and sealing of amateur equipment because of the war brought an end to this production witch again started in June 1919 (Advertisement), now using a thoriated-tungsten filament with a life of 2000 hours. In June 1920 Cunningham gets a license for his AudioTron Manufacturing Company, former called AudioTron Sales Company to sell tubes in his name made by RCA. In turn he has to stop his own patents infringing production. In December 1922 the name Audiotron drops from his adds and the business is named E.T. Cunningham Inc. In April 1931 it is "A Subsidary of Radio Corporation of America". Details see Tyne "Saga of the vacuum tube" page 160ff.

Harry V. Roome in Los Angeles, a 17 year old high school boy sold a very similar tube from January 1916 to August 1916 called Oscilaudion. In July 1916 he named the tube also ThermoTron (The Thermo Tron Company).