This circuit is from the 80's integrated circuit manual itself. The component is not as common today as the MOS transistor used. The circuit can be adapted for modern applications.
Found in 1965 Delco Radio documentation, this circuit uses transistors from that era. Modern...
This circuit was obtained in a 1979 publication but can still be easily assembled today by...
This receiver was found in a documentation by Gernsback from 1960. The circuit uses high impedance...