Found in a European magazine from the 90s, this circuit emits beeps that are several seconds apart to indicate that a device is on. The transducer is a ceramic or crystal capsule.
This timer was found in a 1994 Electronics Now. The relay must be a sensitive type. If it has a...
We can make an oscillating relay producing a rectangular signal taking advantage of the inductance of...
This circuit appears at various points in this section and on this site, with minor variations. It uses the...