This circuit was obtained from a Radio Electronics issue from January 1989. The indicator is a ceramic transducer, and the frequency of the emitted sound is given by C3.
This circuit was found in an English magazine from 1979. The magazine no longer exists, but the...
We found this circuit in a PopularElectronics of 1993. The circuit generates signals whose...
This circuit was found in an English technical documentation from 1973. The circuit generates...