This circuit was found in the February 1981 issue of Radio Electronics magazine. The circuit uses an active component of the time and is suitable for audio signals.
This simple sensitive circuit was suggested in a July 1992 Radio Electronics issue. The relay is a...
Found in an old English publication and in other parts of this website in different versions, this...
This circuit can keep a set of lamps on for up to 1 minute, time given by C2 and R2 that can be...