Re: DC motor (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 1 Aug 2007 21:55:38 -0000 (GMT)
From: huil888@xxxxxxxxxxxx
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: DC motor (fwd)

> Scott -

A universal (AC/DC) brush-type motor is for all intents and purposes
completely immune to "interference", whether radiated or conducted via the
AC line. If it operated normally with the solid-state speed control when
the Tesla coil was not operating, but quit when the coil was running, the
problem was with the speed control, not the motor. If it did not operate
properly when connected to the variac, you had some other problem with the
system (open or intermittant connection, excessive voltage drop somewhere,
etc).

A high-speed AC/DC brush-type motor (like used in a vacuum cleaner) is a
prolific generator of broad-spectrum interference; in the world of EMC, it
is a well-recognized noise "source", not a "victim".

Regards,
Scott Hanson


> ---------- Forwarded message ----------
> Date: Wed, 01 Aug 2007 16:11:41 -0400
> From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Re: DC motor (fwd)
>
> 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.
 (snip)