Hi everybody! Audioguru, your're doing an excellent job! Thank you very, very much for your commitment! I'd also like to built this PSU and understand how it works. As far as I can see there were lots of changes by the component values but the circuit's topology stayed the same except the additional resistor Rl. I've read the function description, but I still don't understand half of this circuit I think.Now here are my questions: 1.This additional resistor Rl forms a load that is needed for correct function of the regulation even if no external load is connected? 2.What is R1 good for? Why is the smoothening-capacitor C1 not enough? 3.Why 15W for R7? With P=R*I^2 and a max. current of 5 amps follows a max. dissipation of 6,75W. Is this because a 15W resistor doesnt get as hot as a 9W resistor? Does this resistor need an extra heat-sink? The lower the value of R7 the better, because less power is dissipated in R7? 4.U1 provides a constant voltage which is amplified by U2. The output voltage is fed back to U2 by R12 (C6 is for stability?). C9 is for stability, but what are R15 (base-resistor for R13?) and D10 good for? 5. I don't know what D11 and C7 are doing. Same with D10 I hope somebody (I think it will be audioguru ;-)) can help. Bye Benno