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.
This traditional triplier configuration with the 555 can be found in other articles on the...
This transistorized oscillator, a modification of the Colpitts oscillator, was found in the...
This circuit is from 1995 documentation. The power depends on the transformer, which in this case...