This buzzer trigger can be used for small alarms. We find it in an 80’s American documentation. The supply can be done with voltages from 3 to 18 V.
This circuit can be interleaved between guitars and guitars to give the fuzz distortion effect. The...
This 1969 Philips documentation circuit makes it possible to control an engine through the sound...
This circuit, suitable for tube equipment, was found in an old documentation. It uses a high...