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.
We found this circuit in the July 1992 issue of Radio Electronics magazine. An optical system...
This circuit was found in a 1973 magazine, but it can still be assembled using modern equivalent...
The circuit presented shows how to use a diode in temperature compensation of a push-pull output...