We found this circuit in a 1987 Hands On Electronics. It was indicated at the time to power cassette recorders with 5 batteries. However, we can change the zener and obtain voltages of 6 V or 9 V. The input must be at least 2 V more than desired at the output. We made changes to the original circuit to facilitate assembly with modern components. Q3 must be equipped with a heatsink.
