This again the one circuit that use in fining value output voltage, for apply give straight with the requirement of load be the circuit that is simple and have no result temperature way of the joint junction of transistor. Vout control 0V-30V at 0.1A The principle works be transistor Q1 2SC458 that built model common-emitter amplifier, which perform fine decrease input voltage get down then heal volt that give may but at collector voltage compare with ground. Which get from the combination of voltage at base – emitter pin (0.6V) with VZener diode (6.2V) already fine the value of a resister can fine the value VR1 help transistor part Q2 2SC458 perform be compared as power supply current source and current that fixed. By current at flow come in the way base pin of Q2 and when Q2 bias current. That already Voltage output get, with fining that a resister VR1 during 5.8V-15.8V. By have R3 and C1 perform be RC Filter caution. This circuit power current source get 100mA topmost should apply to load that use current low.
http://www.eleccircuit.com/adjustable-voltage-output-control-by-2sc458/
