We found this circuit in an American 1980s documentation. The circuit uses a piezoelectric transducer unusual in our day. The transistor is general purpose type.
In the figure below we have the typical circuit of an automotive star alternator with the...
This is the circuit of a commercial flash from the 60’s. We found it in a march 1961 Radio...
This circuit was found in a 1978 British magazine, but it can still be mounted by simply replacing the...