Audion vacuum tube
From RetroTech, the online museum of 20th century technology.
The Audion vacuum tube was invented by Lee De Forest in 1906. The Audion tube is the forerunner of radio tubes that enabled electronic devices such as radios, televisions, radar systems, computers, and “talking” motion pictures. De Forest made improvements to the tube, and in 1916 created the version on display in the museum, which contained two filaments (one on each end), rated at 1.1 amps at 4 volts. The specimen in the collection of the museum was purchased by mail order directly from the inventor in 1920 for $8.50 by Ed Wildner of La Grange, Texas.
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