This circuit operates from 25 to 65 kHz depending on the transducer used and the settings. We found it in the Radio Electronics magazine of July 1985. The 9V to 12V power supply is not given.
We found this circuit in the September 1971 Radio Electronics magazine. The SCR can be any of the...
This circuit uses unijunction transistors and drives a small speaker through an output...
The circuit presented was found in the Motorola Linear Databook of 1990. The power supply is...