Hi Bill,
Have a look at this JBAA paper by Steve Evans -1998 Aug Vol 108 No 4 pp. 204-206
and other references to stepper motor rotating shutter systems
1999 Dec Vol 109 No 6 p.300
2001 Feb Vol 111 No 1 p.33
2001 Dec Vol 111 No 6 pp.337-338
2002 Apr Vol 112 No 2 p.63 & p.94
Cheers,
Alex.
