Current Limited Power Supply

!Open feedback switch before starting! This is a very simple yet effective method of current limiting, the circuit is mostly the same as a basic op-amp regulator except for the PNP transistor on the output, the 0.7 ohm resistor is chosen to drop 0.7V at 1 amp, this drop causes the PNP to turn on which in turn switches on the NPN pulling down the regulator gate voltage, being in an active loop the output voltage will adjust to maintain the current limit, if the set voltage is reduced below a voltage that triggers the current limiting or the load is reduced it switches back in to constant voltage mode.

published 10 years ago