This is a simple but well working current limiter. It can limit currents from a few milliamperes to 2-3 amperes, but can be modified for higher currents by changing the Transistor Q2
The value of R1 can be calculated by: R = 0.6/I. where I is the desired maximum current.
Q1 is any bipolar small signal NPN transistor. I used an BC547C and it worked fine.
Q2 is an NPN power transistor that can handle the desired current. If you want short circuit current limiting Q2 must be able to handle a power which is: maximum current * applied voltage.
