This RF amplifier step has a dynamic range of 140 dB and can amplify signals from 0.5 to 40 MHz. FET is old, but modern equivalents can be used.
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...