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 source was found in a 1982 American publication, but can be easily assembled using 2N2995 (PNP...
This contact or reed switch actuation was found in a 1964 Electronic Design. The circuit can be...
Found in a 1968 Electronics World, this circuit uses components from the era. In this circuit, a...