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 Popular Electronics. Its purpose is to warn the visually impaired when a glass...
This circuit was obtained from a Popular Electronics from January 1967. It has a...
This ultrasonic transmitter was found in a 1974 documentation. The receiver is the CIR11753 or...