This circuit, found in a 1964 US documentation, consists of a selective amplifier that lets only 10 Hz pass around a 400 Hz center frequency with the indicated components.
This circuit emits a warning sound when night falls. The circuit is from a Hands On Electronics from...
This shield circuit is from old documentation. The operational amplifier used is not common today...
This Hall sensor circuit is intended to isolate an audio signal applied through a coil. The...