This circuit was found on a Radio Electronics of July 1984. It consists of a source with the 741 as a regulator and the transistor which can be the BD135 in the control. The transistor must be equipped with a heatsink. Operational amplifiers equivalent with FETs can be used. For a current of the order of 1 A, the TIP31 can be used. The voltage can also be changed in the range of 5 to 15 V with the change of the zener diode. The input voltage must be at least 3V higher than the desired output voltage.
