Found in Popular Electronics from the 90s, this circuit can be used in tachometers. The integrated circuit is not a common component today.
When operating near a medium wave radio, the signal frequency changes and this can be heard on the...
This is one of the possible receivers for the CB4582E transmitter. The circuit is from 1995...
This circuit was obtained from a 1978 Practical Wireless. It makes a speaker emit sound when there...