This circuit that emits siren sound can be used in a fire alarm. We found it in an old American documentation. The signal must be applied to a good audio amplifier.
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...