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.
With an ultra-low consumption, this circuit can be powered by solar cells. The circuit is from a...
This circuit allows you to view two low frequency signals on a single channel oscilloscope. It was...
Adafruit Raspberry Pi Perma Proto PCB Kits Adafruit kits are available from Mouser Electronics...