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.
The operational used is like the 741 and the voltage gain is unitary. The circuit is from the...
This simple windscreen wiper interval was found in old American documentation. The relay must have...
This circuit makes the RIAA equalization of signals obtained from a record player for recovery in other...