On Jan 22, 12:26*pm, wrote:
On Tue, 22 Jan 2013 07:36:49 -0800, Jon Danniken





wrote:
On 01/21/2013 07:22 PM, wrote:
Why do Microwave ovens that have a rotating platter, change direction?
The platter seems to usually spin counter-clockwise. *However, if I turn
it off to stir or check the food, the platter begins to turn clockwise..
It dont change direction once it's running, only when I stop it and
restart. *This is the second microwave I've had that does this, and they
were different brand names.

Not only do I wonder *why* they change rotation, but *how*? *I'm
guessing they use a shaded-pole motor (I'm not sure), and as far as I
know, those motors only turn one direction. *Either CW or CCW.
Unless there's a belt driving them, there is not much room for any other
type of motor in the base of the oven.

They're just little sync motors, like you'd find in a clock. *To save
money, they don't have any provision to determine which way they spin,
so direction of travel is determined by pole proximity.

Jon

Thanks for the info. *That makes sense. *The direction should not matter
as far as how it cooks, since the cooking is done by the magnetron. *The
rotation is just so it cooks evenly. *That much I knew. *Now I know why
it changes direction.- Hide quoted text -

- Show quoted text -

And in the similarly-designed clock motors, there is a little
mechanical gizmo that won't allow the motor to run the clock
backwards. The motor will try to run backwards, the try forward, and
then the gizmo lets it proceed.