This circuit detects when an audio signal exceeds a certain level or even occurs due to an object falling, a door slamming or other. The circuit is from a Radio Electronics from January 1980.
This circuit is designed to control static loads fed by direct voltage. The circuit is from...
The 4046 PLL is uncommon these days. This circuit was found in the August 1994 issue of...
This two-transistor circuit was found in American documentation from the 1990s. The circuit can use...