This circuit was found in an American documentation from the 80's. The components are from that time. It provides a variable output of 18 to 30 V with a current of 200 mA.
Suggested by an Electronics Now magazine from April 1994, these circuits can be used as output...
The simple two-transistor signal injector shown in the figure was found in the May 1971 issue of...
The interesting circuit shown in the figure can have its gain digitally controlled and have two...