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Whacky idea

PostPosted: Sat May 27, 2017 11:52 am
by Andrew Davie
I was thinking about the distinctive sound of the motor as it stutters up and down in speed when the disc is synched. It's quite a howl/whine. I thought mmh, how about a system that takes the disk to slightly over-speed and remains constant, and then control the PID/disk speed with a mechanical "finger" - that is, a friction applied against the end of the disk just like we do it manually. It would be quieter, I'm sure - and the motor would be constant speed, happier. Just thought it was a bit of a whacky idea I'd jot down.

Re: Whacky idea

PostPosted: Sat Jul 21, 2018 6:08 am
by smeezekitty
My solution to PWM whine was quite simple: a big capacitor.

Obviously make sure your motor driver transistor can cope with a big capacitive load. I put a 4700uF capacitor in paraellel with the disk motor.
It quenched an oscillation that kept happening in the PID loop and diminished the PWM whine substantially. It did require retuning te PID paramters though.