50 watt Poulsen Arc Transmitter, 1909


History San José

History San José
San Jose, United States

The original 50-Watt (output) Poulsen arc brought back to Palo Alto from Denmark by Cyril Elwell in 1909. Elwell obtained the U.S. rights to manufacture Valdemar Poulsen's invention, which was considered to be superior to the Marconi spark transmitter. As refined by Elwell's Poulsen Wireless Telephone and Telegraph Company (later renamed Federal Telegraph Company), the Poulsen arc was capable of transmitting a high power radio signal that could span thousands of miles. Federal grew dramatically during World War I manufacturing 500kw and 1000kw arcs for the U.S. Navy under the direction of chief engineer Leonard Fuller.


  • Title: 50 watt Poulsen Arc Transmitter, 1909
  • Date: 1909/1909
  • Location: Denmark
  • Physical Dimensions: 9 x 9 x 9 in.
  • Provenance: Perham Collection of Early Electronics, History San José
  • Type: physical object
  • Contributor: Valdemar Poulsen

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