Found in a 1968 American documentation, this circuit generates 1 kHz signals. The SCR used is not a common component today.
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...