This high sensitivity circuit was found in the July 1992 Radio Electronics magazine. The circuit drives a buzzer, but a relay can be used to activate an external load.
For triggering high-powered loads connected to the power grid, nothing better than using TRIACs. For...
This tube circuit is from an 80's documentation. The filter is of the selective type and the...
This circuit was obtained in a 90s EDN. The components used are from that time. The voltage...