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 was found in a Signetics documentation from the 1980s. The integrated is a PLL and...
This two-channel wired intercom was found in the April 1990 issue of Radio Electronics magazine....
The output voltage of the circuit shown in the figure is approximately 7.0 V for a 15 V supply...