This power supply protection circuit using a relay was found in a 1967 documentation. The components are from the time, but current equivalents can be used depending on the power source current.
A fine adjustment of the output voltage of a power source is achieved with this circuit, which...
With this name, we found this electronic stethoscope with a coal microphone in a 1957 Raytheon...
This circuit can be used as a low Power audio booster for experimental projects such as radios,...