Dave Liquorice wrote:

On Fri, 31 Aug 2012 21:29:28 +0100, Andy Burns wrote:

http://dyson.co.uk/Vacuumcleaners/DDM.aspx

Bollox after marketing have got at it. Looks as if they are stepper
motors to me.

I think you'd need more than 2 poles to guarantee they rotated in one
direction, rather than just vibrate back and forth at 1.7kHz