This is a circuit of a LM317T power supply. LM317T is a very famous and high performance IC comes in TO-220 package. IC requires only few external parts to make a best bench or lab power supply, the IC also has many built in features like thermal overload protection, safe
area protection, current limiter etc. Input voltage is from 3 volt to 40 volt DC and output voltage is DC 1.2v to 37v adjustable and the output current is 1.5A. But the circuit mentioned below will deliver output voltage from 1.2v to 25v with 1.5A. The purpose of limit the output to 25 volt is for making the circuit simple and timeless. Although if you want 1.2 volt to 37 volt adjustable / variable output then make this circuit 1.25V - 37V 1.5A Variable / Adjustable Power Supply Using LM317