RE: dimmer switches

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

Hi Terry:

The dimmer failed in the full-ON mode.  Beyond being full-ON, there were
no fireworks.  The edge of the circuit board was very close to the metal
case, and there was a PC trace very close to the edge of the board.
There was a carbon track from that trace to the edge of the board.  I
had an R-C snubber circuit across the two dimmer terminals, but this had
no bearing on the case-to-trace arc.

I didn't follow what you meant by "a different source impedance to the
typical Telsa coil circuit".  Were you thinking of using such a dimmer
to control the NST  ?  I just used it mine on a "universal" vacuum
cleaner motor for my static gap.  Wow, the saturating shunts on NST's
are enough of a mystery with a sinusoid input.  I can't fathom what
chopped AC will do!

Regards, Gary Lau
MA, USA


>Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
>
>Hi Gary,
>
>I was basically thinking of taking a common store bought dimmer and
adding
>a few protection circuits to protect it from such things.  What did it
do
>to the dimmer?  Did it short to the always on condition?, catch fire?
Just
>curiuous about what needs to be done to provide protection.  Dimmers
also
>present a different source impedance to the typical Telsa coil circuit
>which may alter a finely tuned coils performance in unknown ways.
>
>Cheers,
>
>	Terry 

At 05:46 PM 7/4/2001 -0500, you wrote:
>One thing I would add - Do not connect the dimmer case to RF ground.
>The voltage spikes between the RF ground and the mains lines arced over
>on one I was using to control my vacuum cleaner motor and destroyed the
>dimmer.
>
>Gary Lau
>MA, USA

>
>Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
>
>Hi,
>
>I have never used dimmers but there are a few things I know to watch
out
>for.
>
>Get the biggest wattage you can find.  the higher the wattage the
bigger
>the
>traics in them and the tougher they are.
>
>You need to be very careful of voltage spikes.  Maybe get a bunch of
>MOVs from
>Radio Shack to be sure a spike does not blow it up.
>
>One big thing to watch out for is that if the dimmer fails, it will
fail
>in the
>100% ON condition.  That could be pretty exciting if you are tuning
your
>coil
>or really don't want full power just then...
>
>Variacs are far nicer in that very little can go wrong with them.  But
>dimmers
>are far easier to get.  Maybe someone could figure out a good rock
solid
>dimmer
>circuit to replace a variac for at least the lower powered coils...
>
>Cheers,
>
>        Terry