This adjustable circuit from 0 to 200 nA was found in a 90's EDN. The components can still be found relatively easily, as they are CMOS.
This transmitter for the 40 meter or 7 MHz band was found in a magazine 73 for radio amateurs of...
This shortwave preselector was found in the July 1994 issue of Radio Electronics magazine. The...
This circuit was found in a 1967 RCA documentation. The components are of the time. The circuit...