> >This alternator 
> >http://others.servebeer.com/misc/alternator.jpg has NO
> discernible cogging

> Looks very inefficient to me; like it has a lot of 
> magnetic 'short circuit'!

It's not.

You may be unacquainted with standard winding practice or 
mislead visually by what you think you see. Those are 
industry standard laminations (for some industries :-) ). 
You can leave the inner arms unused if desired - that's just 
a means of getting slightly better spatial utilisation.

That alternator is approximately as good as any. Bear in 
mind that the iron path may be immensely long compared to 
the airgap.

Note that you do get some airgap variations arocc a 
mechanical cycle due to the flat magnet faces approximating 
a circular arc. The result is not vast in practice. It gives 
you a larger net airgap than you'd get with the minimum 
separation compared to what you'd get with a truly circular 
magnet face.

Works entirely well enough in practice.


        Russell McMahon

> >This alternator 
> >http://others.servebeer.com/misc/alternator.jpg has NO
> discernible cogging


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