RE: DC motor (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 1 Aug 2007 20:29:48 -0400
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: DC motor (fwd)

I once used a lamp dimmer to control an AC/DC vacuum cleaner motor to my
sucker gap.  The dimmer failed, and it was much later that I realized
why.  For no good reason, I had tied the metal case to the RF ground.
Turns out that the RF ground has a huge amount of HV transients on it,
relative to the mains.  The insulation between the dimmer circuit board
and the case is minimal, and the RF ground-to-mains transients took out
the dimmer.

Regards, Gary Lau
MA, USA

> I had a motor from a vacuum cleaner that was AC/DC.  It worked great
when
> the TC was turned off, you could vary the speed using a dimmer switch
or a
> variac.  But when the TC was turned on, interference stopped it from
> turning.  Some good shielding might have fixed this, but a simple
grounded
> aluminum foil shield did nothing.  Thanks.
> Scott Bogard.