RE: new coil

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <gary.lau@xxxxxx>

Ahh, my filter doesn't (yet) have MOV's, so the safety is the "last
resort" that I want up close to the NST.

I wonder if the safety is wired in parallel with the main gap, whether
it still makes sense to use a 3-electrode configuration?

Gary Lau
MA, USA

> Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi,
>
> For the "Terry Filter", the safety gaps are indeed across the main gap
just
> as is normal practice.  If the main gap fails to fire or something
goes
> wrong, the safety gaps will catch it.  If that gap fails (or is set
wrong
> trying to get more power ;-)) then the MOVs are the last resort to
protect
> the NST.  The MOVs can also take very fast discharges or a streamer
hit
> with ease.  Even though it seems like overkill, when I looked at NST
> failures it was obvious that you needed the MOVs since many failures
were
> do to both a main gap problem and poorly set safety gaps.  The MOVs
can't
> be set wrong, but they can't take the full load for a long time
either.
>
> The filter not only protects against over voltage, but also goes a
long way
> to protect against the operator too ;-))  Async gaps are getting rare
these
> days but a sync gap can fly out of sync for many reasons too so I made
it
> all as goof proof as possible.
>
> Cheers,
>
>          Terry
>
>
>
> At 09:15 AM 12/17/2004, you wrote:
> >My thinking is that the filter is there to protect the NST, and the
> >3-ball gap is an absolute voltage limiter applied across the thing
we're
> >trying to protect.  Having the safety gap in parallel with the main
gap
> >seems redundant, since the lower voltage gap will always fire first.
> >
> >Why then wouldn't the main gap be an equally effective voltage
limiter,
> >making the safety gap redundant?  Good question and I don't have an
> >excellent answer.  It has been suggested that mechanisms exist that
can
> >generate high voltage transients across the wires between the main
gap
> >and the NST if they're at all long-ish, so that the NST might see a
> >voltage higher than the main gap.  I personally haven't measured or
> >studied this, but it's enough for me to realize that I want a clamp
as
> >close as possible to the thing I wish to protect.
> >
> >Regards, Gary Lau
> >MA, USA
> >
> > > Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> > >
> > > Hi Gary,
> > >
> > > Thats how I read it also.... and that is how I think it should be
> >connected.
> > > ie, safety gap in parallel to the main gap.  Comments??
> > >
> > > Gerry R.
> > >
> > >
> > >  > Original poster: "Lau, Gary" <gary.lau@xxxxxx>
> > >  >
> > >  > Perhaps I'm reading it wrong, but it appears that in the
photos,
> >the
> > >  > 3-ball safety gap is not across the NST terminals, but across
the
> > >  > filter's output, essentially in parallel with the main gap?
> > >  >
> > >  > Gary Lau
> > >  > MA, USA
> > >  >
> > >  >  > Here is a way "too" beautiful one!!  I wish I could just
take
> >the
> > >  >  > "pictures" half that good ;-))
> > >  >  >
> > >  >  > http://www.peninsulators.org/Tesla/nstfilt1.jpg
> > >  >  >
> > >  >  > http://www.peninsulators.org/Tesla/nstfilt2.jpg
> > >  >  >
> > >  >  > But just use old bolts or bent wire for the safety gaps.
You
> >just
> > >  > want
> > >  >  > it to arc over if the voltage on the NST starts to go way
too
> >high.
>