RE: dimmer switches

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Gary,

At 05:37 PM 7/5/2001 -0500, you wrote:
>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.

Interesting!  I am thinking that a high power dimmer with a standard line
filter and MOVs on the "output" side toward the NST may work.  The fact
that they fail full on is sort of a problem.  I wish I could think of a
failsafe way to have it fail "off".

>
>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  ?  

Yes.

>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!

Sound sort of interesting doesn't it :-))

Cheers,

	Terry

>
>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
>
>