This 1967 Raytheon circuit uses a Raystor, an optical coupler with a lamp and an LDR. The circuit can be adapted to use another type of coupler.
The purpose of this PLL circuit that we found in the November 1986 Radio Electronics magazine is...
This circuit is intended for detecting 3 levels power grid voltage, and it can be adapted to...
This circuit, which provides a power of up to 3.5 W, can be supplied with voltages from 9 to 14 V....