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 the April 1983 issue of Radio Electronics magazine. Its purpose is to...
Evidently, this is a project that still needs some improvements. For example, the ignition can be...
This very low voltage regulator for 3 V input (2 batteries) was obtained in a documentation from...