Originally suitable for photography applications, this circuit from a Popular Electronics from the 90s can also be used to time plate baths. The components are common, and the sensor is remote.
This circuit is from a Radio Electronics magazine from May 1989. The source must be symmetrical, and other...
Found in an Electronic Design from the 80's, this circuit monitors a three-phase line, activating a...
This circuit is from the LM3914 manual and can be found elsewhere on this site and from other...