Re: Home Made Variac

• To: tesla-at-pupman-dot-com
• Subject: Re: Home Made Variac
• From: Ed Phillips <evp-at-pacbell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Sun, 13 Feb 2000 11:41:43 -0700
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

>   It looked like copper or at least a metal, and I
> > would think it would short out several turns.  I suspect that anyone who
> > would go to that much trouble would know enough to use the right brush
> > material.
> >
> > Ed
> 
> Hmmmm...   im lost now ....   why wouldnt a carbon brush "short out" the
> several turns as a metallic "brush" would ???  arent both materials made
> to conduct electricity ???  I understand that carbon has some
> resistivity to it but is it that high that it would matter compared to
> say a metallic brush?
> 
> Scot D

	The resistivity of carbon brushes (depending on the formulation) is
much higher than that of copper, so the effect of shorting a single turn
would be much less.  Another point was that the brush seemed quite wide,
so that it would appear to span several turns, exacerbating the
problem.  However, I would certainly think that anyone with the ambition
and patience to do that kind of work would have done his homework well
and all should work OK.  No report as to whether it did.

Ed

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