It was strange to see a regulated power supply consisting of the op amp LM308A and the PNP transistor 2N2905. The output of the op amp does not return to the base of the transistor as usual, but returns directly to the inverting input of the op amp. The base of the transistor is connected to the positive voltage input of the op amp, connected by a resistor and the positive pole of the power supply. Do not know the working principle of the circuit, the role of the transistor, the output voltage regulator is how to adjust, do not know where the source of the circuit? I hope you experts advise!
I was the first time I saw this structure, I understand this:
LM338 - 5.0 is a precision 5V voltage reference, the dynamic internal resistance is very low, the typical value is 0.6Ω, op amp LM308 is the emitter follower connection, 2,3,6 feet equal, that is, V2 = V3 = V6 = 5V, Rs and triodes constitute a parallel regulator circuit, and the op amp is the controller.
Vin ↑, V3 ↑, V6 ↑, Io ↑ (op amp output current), I7 ↑ (op amp supply current), Ie ↑, URs ↑, Uout ↓.
