If you want used easy variable regulator power supply voltage 0-30V at current 1.5A max. I am like this circuit, because it is small but very good.
I uesd IC – LM317T it is quality products ic variable regulator,so i like make in other power circuit.
I made use of a 24Vac 1A transformer,The output of the transformer is rectified by diode 1N4002 or equiv ,and smoothed filter using 2200uF capacitors.
The float-voltage measured here for the 24V transformer was 34V-35V,it is unregulated DC voltage.
The VR1 is control output dc voltage 0V(1.25V) to 30V(32V) at 1.5A max all range.
It is advised that you use this ic with a suitable heatsink.
Main Part
– IC1 = IC LM317T or KIA317
D1-D4 = Diode 1N4002 or 1N4004 or 1N4007 x 4
C1 = Capacitors electroly 2,200uF 35V
VR1 = Variable Resistor 5K(B)
Other detail part,Please see in image.