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.
The regulation of high voltages through common semiconductor circuits, such as integrated circuits and...
The LM2904 is not very common today, but common comparators and operationals can be used in the...
This amplifier circuit was found in a Radio Electronics from April 1959. The circuit needs only 20 mV...