> 2. Power one winding, measure back emf on it, and use your current
> method for the other winding.  At a minimum it increases cogging,
> which means individual steps will happen more quickly and thus emit
> sharper pulses

Adam, works beautifully. I powered one winding with 5V via an 820
ohm resistor and captured the wave from the other winding. This power
level is ample to introduce enough detent for even the pedantically slow

Your thought about cogging hit the snail on the head. I'd been thinking
along those lines myself, but mechanically, forgetting that the very simplest
way was right in front of me

Here's a comparison

http://home.clear.net.nz/pages/joecolquitt/pdg_slow.gif

Top trace is unpowered, bottom is powered, on the same scale

Additionally, the waveform on the powered coil is a lovely sinusoidal
series of positive peaks that can go straight into a comparator. Would
rather not try to capture that with the soundcard at this stage but will do
at some time or my records. With both coils powered, signals from each
are so clean and useable with minimal processing. The noise and bounce
has gone and the motor is much less sensitive to vibration

Thanks for kicking the day off on a positive note !!!

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist