This circuit operating with IC uA723 and add amplified with transistor TIP31 or similiar transistor with TIP31 . Input voltage for circuit about 10 - 40 volt DC , formerly of AC voltage 220 volts or 110 volts , then lowered by the transformer voltage to 30 volts. And the supply output voltage from 1 volt to 35 volt DC you can adjust it on potentiometer R2.
See this circuit power supply below :
Output voltage transformer used 10 to 40 Volts . On resistor Rsc is the current limit set resistor. Its value is calculated as :
Rsc = 0.65 Volt
For Example : If you need current output 2.0 A
Rsc = 0.65 / 2.0 = 0.32 Ohm
So , you must use 0.32 Ohm to current output 2.0 A