Peter L. Peres wrote:

> I deduce from the use of the word 'motor' in the original posting that
> the speed of the unit might slightly exceed the capability of micro-
> switches.

  I wouldn«t have thought the winding bobbin was directly driven by the
motor, so it shouldn«t be *that* fast.  My presumption was that the
lifetime of a *reed* switch would cover the number of turns on a
reasonable number of custom-made transformers or whatever is being
considered.

  Actually, I made further assumptions.  The reference to the need to
count back suggested that the number of turns was critical.  This
further implies the number is relatively low and not particularly fast.
The tone of the posting suggested a non-commercial application (i.e.,
you don«t cut costs on sensors on factory equipment ;-).

  For a (mass-)production system I would change my recommendation to
hall-effect switches immediately.  Either way, the idea of mounting two
magnets diametrically opposite for balance, but offsetting two sensors
on opposite sides so that they are not quite 180Ó (specifically,
adjusted so their overlap dwell equals their non-overlap dwell) seems a
neat way to do it.

  I think of coil-winding machines in the same fashion as lathes (comes
from using one for the other) in which environment optical sensors are
a no-no!

  Cheers,
        Paul B.