> This is very basic stuff that anyone who can spell EE can easily figure out

The immediately following posts suggests that there appears to be more
to spelling  ee / eE / EE /  Ee / eieio than may at first meet the eye
:-). Or the ear. The comments on eg mux rate and visible flicker would
be new to many. The comment on motion effect on mux rate flicker also.
Meter hum as opposed to needle flicker may not occur to people.

I also thought that the initial question was a perhaps less good one
than it could have been. And I was agreeably surprised at the amount
of generally useful comment it elicited.

Some years ago I implemented microstepping of a stepper motor to
achieve smooth variable speed slow motion rotation of a pointer for a
disability aid. PIC with software PWM used AFAIR. Lots of fun. Audio
resonances of the stepper motor and needle system gave some
interesting results. The end result was agreeably smooth. I used a
stepper motor available from RS components because product volumes
were modest and motor availability on demand was more important than
lowest price. On subsequently trying some other stepper motors I found
that the RS motor performed substantially better than the available
alternatives and that I had had a lucky break. I could very probably
have optimised the result for the other steppers but was fortunate in
not having to do so.


                  Russell
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