This stereo circuit is from Japanese 1960 documentation. The circuit was originally designed to work with a tube amplifier, removing power from it. The transistors are germanium.
This very simple circuit uses a phototransistor and a very sensitive relay (reed type) being used...
We found this circuit in Radio Electronics magazine from January 1958. It uses a neon lamp as the...
The integrated circuits in this application are not very common today. One consists of an A / D...