Found in old American documentation, this circuit can use crystals between 27.5 and 33 MHz operating on the third harmonic. The transistor admits equivalent.
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...