[0-30 Vdc Stabilized Power Supply]

Hi Mayhem,
Of course Q2 and Q4 should have a base-emitter voltage drop of 0.7V to 1.2V when there is a load. They are emitter-followers. Yours must be shorted from base to emitter.

Opamp U2 has an open-loop voltage gain of about 200,000 so it should amplify the small error to keep the output voltage from dropping when there is a load.

Hey Audioguru. I allready replaced both Q2 and Q4. Before the replacement i did a diode test with a multimeter on both transistors to verify if they had any problems. They had none. No shorts and only two voltage drops. I believe my problem is in this area because the output (pin6) of U2 varies according to the load, but i don't know where. Is there any other component (or problem in the pcb) that could cause this problem?  What is the function of R1?

[0-30 Vdc Stabilized Power Supply]

Hello Mayhem!
I did make test to my unit and result is next: Output voltage is set to 1.50V and then when I put a 1.5A load voltage falls to 1.37V!!!
Accordingly, there is a voltage drop of about 0.13V!!! How much is Your voltage drop under this conditions?
P.s. My project is not entirely original. I did make a small changes in rectifier.

Hey Kvakva, thanks for doing the tests. My voltage drop is much higher. When i put a load of 1.5A the voltage drops nearly to 0V. I did what audioguru suggested concerning the voltage in the output of U1. I have a steady voltage of 11V, even under load conditions. I'm almost giving up this project, i measured everything that i thought could cause the problem and i found nothing that seems to be wrong. Kvakva, can you tell me what were the modifications that you did in the original project? What transistors did you use for Q1 and Q3? The only thing that i can't understand is the voltage between base and emitter of Q2 and Q4. I measure none voltage drop. I believe i should be measuring 0,7V but i can find the problem. Can you measure also these voltages on your ckt?

Thanks for helping me Kvakva and congratulations for your success!!!!!

Is this the project that you build?