This circuit switches power loads with audio signals. The circuit is from a Popular Electronics from the 90s. The components can be changed depending on the signal used.
This receiver uses germanium PNP transistors that can be used from old disused devices. The...
The circuit below shows how to configure 3 gates of a 7400 to obtain a rectangular signal from a...
This Japanese radio receiver is from the 60s. It has 6 transistors and is powered by 4 batteries with...