Re: Sewing machine motor - reversing direction

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>


> ---8x------
> 
> > Unless your motor has a seperate series or shunt coil, and an armature
coil,
> > reversing the connection to the brushes won't reverse the direction of the
> > motor, since the power to the motor is AC.  The current is reversing
> > direction constantly - it switches every ~8.33 mSec.
 
> ---8x------

> If this is a universal motor, as someone mentioned in another post, how
> about rectifying the supply?

	Doesn't affect rotation direction.  Need to reverse armature
	OR field.  Reverse both (which is what a DC supply
	and reversing switch would do) does nothing: rotation stays
	the same:

> You could then use something like an H-bridge (or just a DPDT switch if
> you don't want to get electronic) to control direction.

	Rotation is unaffected by applied polarity, in the case of
	a series commutator motor.

	best
	dwp