Why is my LM317 current limiter circuit not working?

Submitted by bokeb on Fri, 07/09/2021 - 11:21

Noob here, but attempting to build a current limiter with a LM317 for use with a power supply to give constant current.

I have placed an extra potentiometer (the white one) to simulate changing load conditions - but when I adjust it, I am getting changing amperage - which if the LM317 was working correctly, I'm pretty sure it should not.

For testing purposes, I have not placed the R1 resistor, or connected the third leg of the R2 potentiometer (don't think either of those are needed?)

What am I doing wrong?





LM317 current limiter.jpeg


You need the R1. Moving the potentiometer to the end will short the Adjust leg with output.

  Joined February 12, 2018      696
Monday at 02:11 PM