Power Zener with the 741 (CB1224E)

     This circuit regulates the output voltage of a 12 V source or other value, given by the zener. The transistor can be the BD135 for currents up to 500 mA or the TIP31 for currents up to 2 A. The transistor must be equipped with a heat radiator. The circuit was obtained in a 1980 documentation and changes were made in order to make it viable today.