We found this circuit in a 1964 Electronic Design. It provides 0.5 V signals from 4 kHz subcarriers. Transistors are from the era.
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...