This is the high current dc power supply circuit with 5V output. The high current regulator utilizes an extra winding or a separate transformer to deliver power for the LM317 regulator so that the pass transistors can run closer to saturation and increase performance. For excellent performance the voltage at the collectors of the two parallel 2N3055 pass transistors ought to be near to the output voltage. The LM317 needs a couple extra volts on the input side, plus the emitter/base drop of the 3055s, plus whatever is lost across the (0.1 ohm) equalizing resistors (1volt at 10A), so a separate transformer and rectifier/filter circuit is utilized which is several volts higher than the output voltage.