This circuit for dual-gate MOSFET was found in a 90’s Popular Electronics. The coils are according to the frequency range that must be amplified.
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...