Variable Voltage Regulator using Transistor

This adjustable voltage regulator circuit uses a transistor, Zener diode, and potentiometer to produce a regulated output in the range 0 V to 8.5 V (at 0.5-amps max). The input voltage should be in the range 12 V to 16 V. For the transistor, it uses the commonly available and cheap TIP41A, however this circuit can use a wide variety of transistors with high current handling capability.