We found this circuit in an 80's Electronic Design. It makes use of couplers of the time that can be replaced with equivalents.
This circuit was found in the 1991 Electronics Experimenter's Handbook. It activates a relay when...
Found in a 1967 Delco documentation, this circuit can deliver power from 40 to 50 W at 8-ohm load....
This article is from an old publication by A. Fanzeres. With the advent of the Nuclear Era for...