MX2 ... reducing PWM motor noise ...
MX2 ... reducing PWM motor noise ...
Would a small capacitor between the fan leads serve to smooth the square wave power delivery to the fan? If so, what value would you use? I was thinking of trying about 100uF and going up from there. This isn't a problem with the small fans I've tested, but the high mass and consequent momemtum of the larger fans (120mm Panasonic) makes for a somewhat noisy setup. Isolating them from the case has improved the problem but I was wondering if there is a simple electrical solution. I'm not skilled in PCB analysis ... is there already a cap there between output leads (before I start messing around)?
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Paradigm
- Matrix Orbital
- Posts: 255
- Joined: Thu Sep 13, 2001 6:00 pm
- Location: Calgary, Alberta, Canada
It's strange that you found the larger ones made more noise, I found the opposite. Anyway there is no cap in there. We didn't add a large filtering cap for two reasons:
1) We ran out of space
2) The aditional cost was too prohibitive
By adding somthing large (about 100uF) across the +12/Gnd of the fan it might reduce noise, you'll have to experiment and see. Let us know what your findings are. One word of warning though:
*** MAKE SURE YOU GET THE CAP THE RIGHT WAY AROUND OTHERWISE IT WILL EXPLODE! ***
You have been warned.
1) We ran out of space
2) The aditional cost was too prohibitive
By adding somthing large (about 100uF) across the +12/Gnd of the fan it might reduce noise, you'll have to experiment and see. Let us know what your findings are. One word of warning though:
*** MAKE SURE YOU GET THE CAP THE RIGHT WAY AROUND OTHERWISE IT WILL EXPLODE! ***
You have been warned.
James McTavish, P.Eng
Director of Engineering
Matrix Orbital
Director of Engineering
Matrix Orbital
I have done this with a board I built, Single channel PWM, with temp probe to control fan speed. I believe the noise I see everyone talking about is PWM noise or stutter.
Just wondering if perhaps a helper board would be the way aroud this.
Fans plug into helper board and helper board plugs into the MX, only the fan outputs would go through the helper board.
PWM can be made to work silently ( no stutter) but it does take a few parts.
Just food for thought.
Aardil
Just wondering if perhaps a helper board would be the way aroud this.
Fans plug into helper board and helper board plugs into the MX, only the fan outputs would go through the helper board.
PWM can be made to work silently ( no stutter) but it does take a few parts.
Just food for thought.
Aardil
This could definitely work...however from the tests we have performed the amount of PWM "stutter" is minimal to the wide range of fans experimented. With limitations to the PCB, the best design was developed and implemented accordingly. 
Miles Y.
Head of Technical Support
Product Manager
Matrix Orbital
Head of Technical Support
Product Manager
Matrix Orbital
Miles
I did not mean that MO did anything wrong or did not research this.
Only stating that it can be made silent IF you are willing to go the extra mile.
Something that may not be cost effecient, but would help with the stutter.
My boards that I made are not cheap by any stretch of the imagination.
Your boards have a Digital display, multi channel fan out puts, and thermal control.
My boards have no display other than a couple LED's, Single fan output, but can be loaded down to 5 amp draw, and is temp probe controled.
My boards are about half the cost of yours, but do alot less.
The whole point is, if you are brave and dont mind spending a few extra bucks the PWM can be made to be silent. I understand you have reached what I would call a happy medium with the stutter, and it will be fine for most folks. Just saying there are a few of us that are extremists and there is a way to do it.
Aardil
I did not mean that MO did anything wrong or did not research this.
Only stating that it can be made silent IF you are willing to go the extra mile.
Something that may not be cost effecient, but would help with the stutter.
My boards that I made are not cheap by any stretch of the imagination.
Your boards have a Digital display, multi channel fan out puts, and thermal control.
My boards have no display other than a couple LED's, Single fan output, but can be loaded down to 5 amp draw, and is temp probe controled.
My boards are about half the cost of yours, but do alot less.
The whole point is, if you are brave and dont mind spending a few extra bucks the PWM can be made to be silent. I understand you have reached what I would call a happy medium with the stutter, and it will be fine for most folks. Just saying there are a few of us that are extremists and there is a way to do it.
Aardil
