1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution I need to know if my understanding of this circuit is correct in terms of R1, R2, Q1, Q2. R1 is a sensing resistor and when Q1 senses a voltage drop at its base, it switches on and passes current around the regulator. I think when there is excess current at Q1 it switches off and error resistor R2 senses a volt drop to switch on Q2 at the base to divert current away from Q1. I think I'm close, who knows.