Re: Can a light dimmer substitute for a variac when setting up a tesla cilo?

Many of us sorely wish triacs worked for transformer control, but they
perform very poorly in this function.  I believe it is because the waveform
coming out of a triac at partial power setting is no longer a pure sinewave.
I'm sure some of the degreed engineer types here will give a more learned
description of the exact mechanism of why triacs don't work with
transformers or brushless motors.

On your variac question, you can run any variac up to twice it's rating for
short runs of a few minutes and up to 3 times rating for a few seconds.  A
high-volume air blower directed through the variac can greatly increase
power capacity and reduce cool-down times.  I've wondered about oil cooling,
but concerns about oil between the brush and copper have kept me from trying
it.  If oil does work, you could really push a variac - at least up to the
point where the core saturates.  Then the wild ones get out their hacksaws
and slice the core.  We're all madmen here.

Bert Pool

-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Monday, March 01, 1999 3:57 PM
Subject: Can a light dimmer substitute for a variac when setting up a tesla

>Original Poster: "David Hosking" <davidhosking-at-bigpond-dot-com>
>Hi to all,
>I have read the posts on changing motor speed with a light dimmer and was
>wondering if you could use a dimmer to replace the variac supplying the
>to operate the tesla coil at low power for setting up.
>Also I am able to buy a 500va variac and my coil is using 2x15kv 60ma NSTs
>Could I use this variac for short runs with a good cool-down after?
>If so,  how long should my maximum run time be?
>Many Thanks,