First Manmade Amplification
This Western Electric mechanical amplifier is the first known device for amplifying audio signals.
Produced mid-first decade of 1900, the input fed the receiver coil (the part of a telephone you put to your ear).
The receiver’s membrane was mechanically connected to the carbon button microphone, which was connected to a battery source.
The Western Elecric was followed by "repeaters" by two companies: Brown and Shreve in England.
Then Austrian physicist Robert von Lieben was the first to patent a vacumn tube power amplifier, used for long distance telephone transmission.
It was manufactured by Gesellschaft fur Drahtlose Telegraphie in Berlin in 1912.
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