This circuit is from a 1980s Signetics documentation. The circuit separates the modulation signal from a carrier. The used components are not common today.
Found in a 90's EDN this circuit can be used as a shield. The transistor is a general-purpose type and the...
This circuit was found in the November 1992 issue of Radio Electronics magazine. The circuit has...
This circuit was found in an American documentation from 1977. The circuit can be implemented with modern...