Found in Texas Instruments documentation from the 1980s, this circuit applies to digital signal transmission with FSK modulation. The circuit is slow, as it uses period components.
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...