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 from a 1957 Raytheon transistor manual. The diode can be of general-purpose...
The circuit shown in the figure shuts off a load when the voltage drops below the value determined...
This circuit was obtained from an English magazine from 1976. The signal from the circuit should be...