This circuit was found in a Popular Electronics from the 90s. The circuit uses an ultrasonic microphone. The indicator is dual with LED and Buzzer.
This circuit separates the bass from the treble in an audio signal. The circuit is from a Hands On...
This circuit was obtained in a 1986 documentation consisting of an active frequency divider for...
We found this circuit in a Popular Electronics from 1992. It consists of a voice scrambler used in...