This circuit is intended for underwater communications. Of course, the critical point is the shielding to avoid water. The circuit is from an Electronic Hobbysts Handbook from the 90s.
This circuit mimics the dialing of an old telephone. The reproduction is made in a loudspeaker and the power...
The gain of this circuit depends on the frequency of the input signal. The circuit is from a Radio...
This tone control was obtained in a Signetics documentation of the 90s. The integrated circuit can be...