As shown in FIG circuit, T is auto voltage regulator. Its output fixed input end by a servo motor to automatically adjust the output remains constant.Transistor VTl, VT2: 3DK9C, = 65 ~ 85; VT3: 3AX818, = 60 ~ 80; diode VD2, VD3, VD6 ~ VD9: 1N4002; VD4,..