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Re: Smoking the Neons!



Tesla List wrote:
> 
> >From jgore-at-cyberramp-dot-netSun Oct 20 21:34:20 1996
> Date: Sun, 20 Oct 1996 01:48:51 +0000
> From: jgore-at-cyberramp-dot-net
> To: Tesla List <tesla-at-poodle.pupman-dot-com>
> Subject: Smoking the Neons!
> 
> >Determine if you actually need a rotary. If you're only going to drive
> >from neons, a rotary won't improve your performance. - it'll only
> >smoke the neons!  Don't try to go cheap and dirty on a rotary.
> 
> Could someone explain this statement? How does using a rotary hurt my
> neon sign transformers, and or my caps? I'm not being critical here, I really
> just don't know!
> I've designed my coil to use two 9KV neons, to make about 3 foot
> arcs. Is a rotary really going to blow it? what could I do to make a
> rotary work with a small coil like this?
> Thanks for any info...........................Jerry
> -=*< If your not shooting in 3D then your not getting the whole picture >*=-

Jerry,

Jim Fosse had a recent post that concisely described the problem. If the
rotary gap is not synchronized to the 60 Hz power coming in, there will
be times when the voltage stress on the neons exceeds their insulation
capability. This is especially true if you've sized your cap to be about
the maximum for your neon's current rating. 

If you still want to use the rotary, put a single static gap across your
transformers. With everything else disconnected from the neons, set the
gap spacing to be just a little bit wider than the arcover distance. Now
hook up the rest of the system. If the rotary "misfires" the static gap
will fire, preventing severe overvoltage getting to the neons.

You also should add series inductors, caps to ground, and safety gaps to
ground for reducing RF coupling to the transformers, and to provide a
path to ground for any secondary "hits" that may couple into the primary
circuit. 

Safe coilin' to ya!

-- Bert --