6VDC Amplifier (T485E)

This drum amplifier was found in an American documentation from 1947. It makes use of a mechanical vibrator to generate high voltage for the tubes.

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Logarithmic amplifier (CB9020E)
We found this configuration in a 70s American documentation. The circuit makes use of operational...
DC Amplifier MC33171 (CB14469E)
The circuit shown is powered by 5 V and was suggested by Motorola's Linear Databook of 1990....
Transistorized Intercom (CB17173E)
This simple transistorized intercom circuit was found in a 2000 documentation. It can be powered by a...