Tuesday, September 21, 2010
This circuit uses LM723 IC that provides a very good voltage regulation. The 3 pass transistors connected in parallel with LM723 require heat sinking. The output voltage is tuned to 13.8V by resistor R9 and the resistor network formed by resistors R4 through R7 controls the current limiting. The LM723 limits the current when the voltage drop across R5 approaches .7 volts. The thermal runaway is not a problem here because the circuit samples the collector current through pass transistors.