This basic Schmitt trigger was found in an American publication from 1968. The circuit uses transistors from the time. Modern general-purpose types can be used.
This telegraphy circuit generates an audio tone from a pure RF carrier. We found it in a...
Found in Popular Electronics from the 90's, this circuit uses 555 integrated and common...
This circuit was obtained in a 1982 English magazine. It is a regulator for outputs between 1 and...