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.
The LM317 will deliver more than 1A of electric current to drive the bases of the pass transistors and assumming a gain of 10 the combination ought to supply 15A or even more. The LM317 normally operates with a voltage variation of 1.2 between the output terminal and adjustment terminal and needs a minimal load of 10mA, so a 75 ohm resistor was selected that will draw (1.2/75 = 16mA). This same current flows via the emitter resistor of the 2N3904 which generates about a 1 volt drop across the 62 ohm resistor and 1.7 volts at the base. The output voltage is set using the voltage divider (1K/560) so that 1.7 volts is used to the 3904 base when the output is 5 volts. For 13 volt operation, the 1K resistor could be altered to about 3.6K. The regulator has no output short circuit protection so the output most likely ought to be fused.
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