| Author | Message | |||
     Kelly Ullrich Moderator Username: Kellyu Post Number: 263 Registered: 02-2007 Rating: N/A |
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. I don't want to take credit for this find, just share my experiments with everyone. Thanks Bill for turning me on to these. Bill's parts can be found here...http://www.allelectronics.com:80/cgi-bin/category/235/Ferrites.html
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| Matthew Wills New member Username: Blacksmith Post Number: 8 Registered: 10-2007 Rating: N/A |
Hi Kelly, I'm curious if your motor cables are shielded. If they are, is the shield grounded at both ends? Thanks, Matt | |||
| Kelly Ullrich Moderator Username: Kellyu Post Number: 269 Registered: 02-2007 Rating: N/A |
No shielding on the cables, Actually I'm using 16 gauge discrete wire (THHN) and cable tie-ing it together. The shielded wire I want is very expensive and I only need a few feet. I did see some on EBAY that can be purchased in 10 foot or longer lengths for a low price. I may change to that some day. | |||
| Matthew Wills New member Username: Blacksmith Post Number: 9 Registered: 10-2007 Rating: N/A |
Kelly, If the wires are small enough to allow it, wrap them through the core 2 or 3 times. This will really increase the suppression with those ferrite clamps. Regards, Matt | |||
| Kelly Ullrich Moderator Username: Kellyu Post Number: 273 Registered: 02-2007 Rating: N/A |
Great tip! Thanks Matt! | |||
| Iain McFetridge New member Username: Iain Post Number: 38 Registered: 10-2007 Rating: N/A |
Hi Kelly..I recently(as you know) ran into the same problem with my limit switches triggering wildly while cutting and K-cam would loose all track of where it was or where home was after a cut session..I used your trick of using clamp filters but I found a more stable (for me) sollution.. on the back of Max stepper I added a .1 Mfd ceramic capacitor between ground and each limit switch conntact/terminal and that brought the noise level from .2 volts of noise to .002 volts of noise. the diffrence on my scope was night and day as far as the noise went..I tryed the caps across the switch but it didnt dampen the noise enough so I moved them to the max stepper board and solved all my problems..for those that dont have Max stepper I would sugjest doing the same thing to your stepper controler at the limit switch termanals on your controler..total cost for me was less than a dollar for 10 capacitors. | |||
| Kelly Ullrich Moderator Username: Kellyu Post Number: 286 Registered: 02-2007 Rating: N/A |
Good idea! I am currently using a surface mount prototype driver/maxstepper board that does not give me the option of easily adding the caps so beads are my only option. My other setups were relatively noise free and didn't need beads or caps. |
