P1 sets maximum current of power supply, if do not need or want to be able to decrease amperage, then you can remove P1 and connect P2 to the 680 Ohm resistor. P2 regulates output voltage between 0 and 18 Volt DC. P1 trims to calibrate M1 voltage meter. RFC1 and RFC2 are 50 turns 1 mm AWG on ferrite diameter 0.8 mm.
The two Final transistor 2N3055 of the power supply need large heatsink for cooling.
