Found in a 90s Popular Electronics, this circuit allows to select the operating ranges between short waves and VHF. MOSFET is uncommon today.
This capacitor for small capacitances is based on the tuning of a receiver circuit. The variable is...
This distortion circuit was found in an American publication from 1970. It can be assembled with...
This circuit generates audio signals for testing amplifiers and other equipment. The potentiometer R5...