This traditional circuit generates a 200 Hz sinusoidal signal. The frequency depends on the capacitors and the transistor can be a BC548. We found this circuit in a 1979 documentation.
The simple mixer presented can be used to mix the signals from low intensity sources, applying them to...
This circuit cuts out ads between songs, based on the fact that the speech signal has small...
This small unregulated variable power supply was found in an American book from the 60's. The...