If you have the skills and can get your hands on SMD components, you can assemble this small amplifier. We found it in the Radio Electronics Experimenter special edition from 1990.
This circuit found in a European publication from the 1980s, is based on PLL 566. The frequencies...
This circuit, which can be used safely, has been obtained in a 1987 documentation. It consists of a...
This circuit detects when a powered circuit suffers a malfunction, lighting an LED. The supply...