Re: TSG update

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi John -

Thank you for the update. I agree with you on many points. First and
formost, is to
get the TSG to work reliably. With this in mind, I think it is a good idea
to give
the Jon Tebbs zero-detecting driver a try. I'll be building up this circuit as
well.

Assuming this circuit grants the phase range and the phase range is linked
to your
inability to turn up the variac beyond 116 VAC (or something else in the
current
circuit), the loudness / brightness at the gap is another issue we should
resolve.
That noise to me is a clear indication of power not getting to the sparks
at the
toroid. As you know, when a coil performs well, the spark noise at the
toroid is
loud and the gap noise is there, but in the background.

I think heatsinks and airflow will be necessary to get near srsg performance if
that's possible. I don't think electrode material is as important as those two
items (keeping the temp regular and ions cleared out).  As far as construction,
well the RQ style gap I built for this was pretty simple and definately simpler
than an srsg. The addition of zero moving parts is also kind of nice. If we
can get
performance up there, it will probably be a winner.

Thanks for the update,
Bart
--
Barton B. Anderson
http://www.classictesla-dot-com


Tesla list wrote:

> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<FutureT-at-aol-dot-com>
>
> Hello all,
>
> I did some more tests using the TSG.  I wanted to test the
> arrangement that Weazle mentioned of grounding the HEIC
> core, and using a capacitor from the HV terminal to the
> trigger electrode.  I tried this, but the safety gap still fired
> even with the TC not running.  The spark is seeking ground
> though the safety gaps.  It seems that most folks use a
> Terry filter and the filter gives enough blocking to the
> pulse so the safety gaps don't fire.  I never use any kind of
> protective filters on my coils, I just use safety gaps.  It's a
> good idea to use a filter though, because the RF is not good
> for the NST windings, although I've had no failures.  Coilers
> who don't use filters need to consider this issue of the safety
> gaps firing.  I find that most NST failures result from setting
> static gaps too wide, so they fire unsteadily.  I generally use
> a sync rotary rather than a static gap because of the great
> smoothness and performance of the sync rotary.
>
> To solve the issue of the safety gaps firing using the TSG,
> I connect the HV terminal directly to the trigger electrode,
> I ground the HEIC core, and I connect a capacitor from
> the HEIC core to each electrode of the main spark gap.
> This lets the trigger electrode "see" ground though these
> caps, and it seems to work OK.  The safety gaps don't fire.
>
> I'm able to turn the power up to about 116 volts on the variac, higher
> than that, the coil runs unsteadily.  I'm not sure if there's a quenching
> problem, a phase range problem, a jitter problem, or gap adjustment
> problem.  As a test, I shut off the fan, and then I could only turn the
> variac up to about 113 volts before the unsteadiness began,
> and the sparks were shorter.  So it's quite possible that
> quenching is becoming an issue.  I think I need more phase range
> too.  I tried various gap spacings, and I couldn't really get it to
> work any better than it is now.  This TT-42 coil may draw
> almost 800 watts or so, and I think some folks have said they
> needed a good airflow at 800 watts.  This suggests that it may
> not be possible to build a TSG which quenches well at 800
> watts or higher without special techniques, such as using a
> multiple gap, an air blast, or certain electrode materials.  I'm
> using silver gaps which may not be the best at these powers.
> If the TSG needs such extra parts at high powers, it may no
> longer be compact or simple to build.  I can't help but believe
> that the ferocious brightness of the TSG spark, along with the
> purported loudness, signify substantial gap losses compared
> to a sync rotary.  A sync rotary gives a much more muted gap
> arc.  As it is, my rotary is a lot smaller and simpler
> than my combined TSG setup.  Rotaries are very simple devices,
> but the required machining to build them scares off some folks.
> Nevertheless, until I obtain adequate quenching, and phase range,
> I can't complete my comparison of TSG vs. sync rotary.  I may
> need to build the John Tebbs 555 timer based circuit so i can
> get enough phase range, and cure any possible jitter problems.
>
> Cheers,
> John