Re: async rotary control

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "D.C. Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>


Your dimmer may not be giving it a nice looking sine waveform.  Check it
with a o-scope or for a quick test just replace the dimmer with a variac and
see what happens.

Dr. Resonance




----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, August 21, 2002 11:13 AM
Subject: async rotary control


> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<A123X-at-aol-dot-com>
>
> I have an async rotary made from a 12000rpm angle grinder. Even with only
2
> electrodes in the disk it's 400rpm and I wanted to try varying it's speed
to
> something lower. I was going to use a dimmer switch but when I turn down
the
> dimmer it actually sounds like it speeds up and also vibrates more. Any
ideas
> of why that happens? Also I was wondering if a cheap variable transformer
> could be made by winding one or two layers of magnet wire on a normal EI
core
> then sanding the windings on one side and making a device with brushes on
it
> to slide across the sanded side to vary the voltage? I really don't feel
like
> buying another variac to control the rotary but I have a nice core and
some
> thick magnet wire to use and I couldn't think of any reason why a variac
> needs a O core except so that it allows for the use of a rotating
contactor.
>
> Mark
>
>