I have been experimenting with filters after a KCam user(Bill) suggested it to me. I have been using the www.Digikey.com 445-2040-ND ferrite clamp filter with great success and I wanted to share my results. One of my driver board/MaxStepper setups is very very sensitive to motor noise. While running an axis it spontaneously trips the limit input or modifies the motion command. I've tried resistors and capacitors with little success. After experimenting with clamp filters, I think these are the solution to my noise problems. I tried placing them on the motor lines in various positions along the cable. The best position was close to the driver board. It even takes two filters on each line to reduce the noise to where it works perfectly. One helps but not for long. I can hear distinct clicking from my motor as it travels at slow speeds. My scope shows those clicks to be noise induces into the PCB and it appears to mess with the MaxStepper processor. When I add one filter the clicks are fewer. When I add a second they are almost completely eliminated and no more nuisance limit trips. If I slide them away from the motor driver board, the noise increases again until I return them near the board.