This circuit was found in an Elektor from the 90s. It is a circuit that generates different types of sound effects. The components are still common today.
This circuit is from the component's own datasheet, which is a quadruple equivalent of the 741....
This circuit is intended for detecting 3 levels power grid voltage, and it can be adapted to...
This circuit that can be assembled in an “aspirin box” was found in the Radio Electronics magazine of...