On This Day in Telephone History October 20TH 1906 The first vacuum tube amplifier was announced. Dr. Lee De Forest announced at an American Institute of Electrical Engineers meeting his ‘Audion’ - first of the vacuum tubes as we know them today. De Forest was granted U.S. Patent 841,386 for his early two-electrode version of the Audion on November 13TH, 1906

On This Day in Telephone History October 20TH 1906

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On This Day in Telephone History October 20TH 1906 The First Vacuum Tube Amplifier was announced. Dr. Lee De Forest announced at an American Institute of Electrical Engineers meeting his ‘Audion’ – first of the vacuum tubes as we know them today. De Forest was granted U.S. Patent 841,386 for his early two-electrode version of the Audion on November 13TH.