Current limiting high current voltage stabilizing circuit diagram

The selection of resistors R1 and R2 in the figure must meet the condition of R2》5·R1. For example, R1=0.2 ohm, R2=1 ohm. The actual mid-apparent current requires R1 to be between 0.1 and 2 ohms, and Ube=Ud has the relationship UR1=UR2, so I2 is about 5 times smaller than I3, the total current I1=I2+I3≈I4, ignoring the base current of the transistor, Then I3 is equivalent to the regulation current of the integrated circuit IC. For transistors with large current, resistor R3 can be selected between 10 and 20 ohms. For small current transistors, 100 ohms can be selected.

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