This circuit was found in a 1969 Mullard publication. The transistor may be the modern equivalent of BC548. Observe the relatively high supply voltage.
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...