On Tue, May 29, 2012 at 2:13 PM, Denny Esterline wro= te: > I've not used _linear_ motorized pots, but the rotary ones I have used we= re > quite slow. Inertia and friction were basically non-issues. > The other detail is they had slip clutches so the knob could be moved > without the motor, this also acted to slip when the motor "hit" the end > stop. These ones can zip along fairly quick, but from what I'm now hearing, inertia and friction might not be as big a problem as I was initially thinking. I think I'll try to whip up a quick circuit at some point and just try it to see what happens. > Yes, an H-bridge is a necessary driver. You can get these as a driver chi= p > (TI's DRVxxx series comes to mind) or do it with discrete transistors. I wasn't able to locate much that was relevant in the DRVxxx series. Admittedly TI's website seemed to be acting a bit weird so perhaps I missed something. Do you have any more exact reference that I can search for on there? > For my money, PID is complete overkill for this application. i drive lots > of resistive feedback linear actuators with full ON-OFF control and a > deadband of +-2 ADC counts, never seen a hunting problem with that. > > Good luck. > -Denny Thanks! Josh --=20 A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. =A0 =A0 =A0 =A0 -Douglas Adams --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .