> Can anyone tell me if it's OK to use a "unipolar" stepper (i.e. one that
> has center-tapped coils) *as* a "bipolar"?   i.e., just ignore the center
> tap and use the two series-connected coils as one.  I realize that this
> might not be as low of a resistance value as what I might see with an
> actual "bipolar" single-coil device, but the question is... will it work?
> My instinct is that it should, but perhaps with less startup torque.  What
> say you all ?
> Thanks!
> Jim

If the center tap is connected to power and you ground either end of the
coil, current will flow from the tap outward to each end. If you place the
entire coil across the power supply, one half of the coil will see
current flowing outward, and the other half will see current flowing
inward. The behavior of the motor when two halves of a coil are energized
in the same direction may not be well defined. It depends on how the
magnetic path inside the motor flows.
Also, the tapped configuration allows for half-stepping by turning on
only one half of one coil while both halves of the other coil are off. Using
the coils as unipolar, you won't be able to do that.

John Power

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads