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.
We found this configuration in the Linear Applications Handbook of the National Semiconductor of...
This circuit is an application for an operational amplifier with field effect transistors from...
This circuit was found in an old Radio Electronics, but can still be assembled as the components are...