Re: Suicidal Secondary--Update

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

James,

You need a longer secondary winding... you are still overvolting your
secondary with the 5 Joule bang size. Your options are either to close
down your gaps or wind a new, longer, secondary. If you do the latter,
use a larger diameter wire gauge with at least double build insulation.

Good luck!

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "James B by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<zebulan123-at-yahoo-dot-com>
> 
> hi Winston
> A six inch coil should take 1.5kva fairly easy. in my
> experience a three inch coil will take up to 2 kva.
> maby i missed this, what is the geometry of the
> primary id, od, Angle, ect.
>                   james
> --- Tesla list <tesla-at-pupman-dot-com> wrote:
> > Original poster: "by way of Terry Fritz
> > <twftesla-at-qwest-dot-net>" <Esondrmn-at-aol-dot-com>
> >
> > In a message dated 1/11/02 7:47:35 AM Pacific
> > Standard Time, tesla-at-pupman-dot-com
> > writes:
> >
> >
> > >
> > > >
> > >
> > >    Hi everyone.
> > > First I should thank all who gave suggestions.  I
> > just got around to
> > > running the coil tonight, and had a chance to put
> > a few of your ideas to
> > > work.  I patched the craters from last week's run
> > with 5 min. epoxy, put
> > > plexiglass washers around the top half of the
> > coil, and rested a 3" dia.
> > > toroid on the top washer as an anti-corona ring.
> > >
> > > These worked to some extent, but not as well as I
> > hoped.  I got no full
> > > secondary arcs, but had many hot racing arcs
> > trying to find a way around
> > > the washers.  There were also arcs running in
> > between the washers.  I
> > > did the coupling calcs. that Terry suggested, and
> > found that the highest
> > > coupling I achieved was 0.12.  It sure looks like
> > I'm overdriving the
> > > heck out of the coil, but I'm only running at
> > 1.5kVA.  The bang size is
> > > about 5 joules.  I tried both toploads (6" by 20"
> > and 8" by 22"
> > > toroids), with the coil tolerating the smaller one
> > best, but with much
> > > decrease in spark length.  My big topload gave the
> > coil trouble, but
> > > cranked out 4 1/2 ft. sparks (at the most).  This
> > run was done in moist
> > > air, when the racing arcs are less of a problem.
> > Running the coil on a
> > > dry day would probably be a disaster.
> > >
> > > I'm sorry if I'm being a nuisance, but I am really
> > at a loss here.   I
> > > can't see how many of you are able to crank 4 and
> > 5 kVA into a 6 inch
> > > coil similar to mine (achieving sickeningly large
> > sparks in the process
> > > :-))  What did I do wrong?
> >
> >
> > -- snip --
> >
> > Winston,
> >
> > In my opinion, racing sparks on the secondary are
> > caused by either running the
> > coil out of tune, overcoupling or just overpowering
> > the coil - putting in more
> > power than it can take.  I use two toroids on both
> > of my coils, one right on
> > top of the secondary (to prevent sparks from leaving
> > from the top windings)
> > then another raised up on a hollow cylinder made out
> > of aluminum sheeting.  The
> > upper toroid is larger and most of the discharges
> > will leave from the here and
> > go up and out, preventing strikes down into the
> > primary.  My 6" coil produces
> > sparks that are more than three times it's winding
> > length.
> >
> > Have you done the math on this coil so you know
> > approximately where it should
> > be tapped on the primary?  Is the best tune point
> > within a turn or so from
> > there?  If so, I would suggest that you are
> > overcoupled.  Is your primary
> > flat?  A normal flat primary usually provides
> > acceptable coupling with the
> > first secondary turn set to be even with the top
> > plane of the primary.  Lay a
> > ruler on the primary and it should be just even with
> > the first secondary
> > winding.  If you have an inclined or saucer shaped
> > primary, the secondary will
> > need to be raised up possibly an inch or more to
> > prevent overcoupling.
> >
> > Ed Sonderman
> >