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 circuit is from an English publication from 1978. The transistors can be the BC548 and the...
This circuit was obtained from a Radio Electronics issue from January 1989. The indicator is a...
This frequency modulated light transmitter is from a 1990s documentation. The circuit may use...