At 09:27 AM 4/18/2012, Denny Esterline wrote: > > > > It sounds like your hall sensors are out of phase (rotated) with > > respect to the magnetic fields. Another way of saying this is that > > your hall sensors are lagging in one direction and leading in the > > other. > > >This is my leading theory at the moment. But, nothing from the manufacture= r >suggests an intentional timing advancement and if it was a missasembled >motor, I wouldn't have expected it to affect two different motors from >different assembly lots. I don't know anywhere near enough about BLDC (yet) but I do know that=20 I run into documentation that talks about two different amounts of=20 hall-effect phase shift - I *think* the numbers mentioned are 60=20 degrees and 120 degrees. This comes up when looking at BLDC motor=20 driver circuits (and chips). My recollection is hazy - I was looking=20 at this a couple of years ago. I suspect that you are expecting one of these and the motor=20 manufacturer is using the other. dwayne PS - if what you are working on can be shared, I'd love to hear about=20 it. I purchased a quantity of decently-sized BLDC servo motors=20 several years ago and I very much want to do my own drivers for=20 them. My fall-back position will to simply purchase pre-programmed=20 PIC chips from JRKERR (his PIC-SERVO series) - but I'd *really* like=20 to get into the nuts and bolts of how its done myself. dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .