The circuit is from a June 1995 Electronics Now. The relay is power-dependent and both R1 and R2 should have close resistances in operation.
This circuit was found in a Radio Electronics magazine from October 1987. It can be used as a...
This setting appears elsewhere on this site. This was obtained from an 80's Circuit Encyclopedia and...
This circuit was found in an Electronic Design from the 90s. The circuit uses a type J...