This circuit makes use of comparators and common operational amplifiers, having been found in Motorola Linear Interface ICs of 1993. The circuit requires symmetrical source.
January 2017 - Omron G7L-x relays for PCB mounting can now be purchased from Mouser Electronics. These...
The circuit below is from National Semiconductor's Linear Applications Handbook. Integrated...
This circuit appears elsewhere on this site. This is from an American 80's circuit manual....