This circuit was found in a RE Experimenter Handbook from the 90's. The components are of the time, rare nowadays, except the 555 and 4017.
This circuit can function either as a crystal or galena receiver with a pre-amplifier using a FET...
Found in an EDN from the 1980s, this circuit uses a double 555. The circuit activates a relay that...
This circuit is from 1992 documentation, but it can still be assembled today, as the components used are...