An 50v bench power supply can be made using electronic diagram below which is designed using LM10 op amp and 2n3055 transistors. This LM10 2n3055 50v bench power supply allows an output voltage regulation in a range between 0 and 50 volts and the output current can be limited to a maximum of 2 A.
Output voltage increases linearly with the amount of resistance potentiometer P1, while the current can be adjusted linear using potentiometer P3. Potentiometer P2 serves to regulate maximum output current (maximum value is 2 A).
Voltage stabilization is achieved as follows: IC1's inverting input is at potential output voltage, noninverting input is connected to common point R1/P1. The operational amplifier command’s T1 so that any difference in voltage between its two inputs to be compensated. Collector current of this transistor produces a power on the R6, it influences the output voltage by Darlington final stage.
Reference voltage on R1 should be 200 mV. Current through this resistance which is about 100 uA, can pass only through P1.
To maintain stable output current at the second LM10, the reference voltage picked from the P3's slider is compared with the voltage drop on R11. This flow current output resistance.