Found in a 1964 Philips manual, this circuit uses only passive components. The relay is a high voltage sensitive type.
Found in an article in the August 1971 Radio Electronics magazine, this circuit supports sensitive...
July 2017 - Mouser Electronics announced the availability of Littelfuse's GEN2 series Schottky...
This circuit is from Radio Electronics from April 1977. The circuit is for analog lines using...