We found this circuit in an Australian documentation from 1991. The circuit is suitable for SMD mounting thus making it very small. The circuit was sold in a kit at the time.
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....