This circuit was found in the June 1995 Electroics Now magazine. The relay should be a sensitive type with up to 100 mA trigger current.
We find this circuit in an 80's EDN. The circuit can be used with equivalent operational,...
This circuit is from a 1992 publication, but can be mounted very easily today. The circuit is...
This buffered version of the previous circuit appeared in an article in the September 1989 Radio...