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 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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