Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>
Thanks. I just added another 30 Hz to my VDF setup, so
I can go from 30 to 150, with a 1725 RPM motor. That
will allow breakrates of up to 575. At current power
levels, I get better length at around 70 - 80 Hz,
which is around 280 bps. I started this coil back in
2003 if I recall. While I say I've played with gap
spacing some, I kinda concider this weekend to be
first light, as I was unable to get the rsg to "keep"
the spark, as my safety gaps always took over. I'll
keep playing and will look for a big resistor to use
in line with my welder. I'vwe always read about some
folks needing resistive ballast, but I thought that
was just to keep their welder happy. I have two slide
chokes that I plan on using instead of my welder. Do
they also need the resistive ballast, or is this more
of a welder ballast issue?
Adam
--- Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: FutureT@xxxxxxx
>
> In a message dated 3/25/07 8:53:32 PM Eastern
> Standard Time,
> tesla@xxxxxxxxxx writes:
>
> >Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>
> >
> >I've noticed a number of large coils use arsg's
> with
> >no problems, while others seem to need a static gap
> in
> >series with their arsg. Mine seems to be the
> latter.
> >Does anyone know why some need this and others
> don't?
>
>
> Adam,
>
> This is an interesting question and I think it's
> affected by
> various factors. Factors such as coupling,
> ballasting,
> transformer voltage, cap value, power level,
> mechanical
> dwell time, rotary gap spacing, electrode speed,
> etc.,
> could affect this.
>
> With a high break rate, a small amount of ballasting
> is usually needed to obtain sufficient power
> throughput.
> This small amount of ballasting makes the gap appear
> more like a short to the transformer when the gap
> fires.
> The gap may try to power arc, or it may try to
> re-fire
> again while the electrodes are still aligned which
> will
> cause inefficient operation and heavy current draw.
> This especially true with a slow rotary speed and
> with
> wide diameter electrodes. This becomes even more
> true
> when the rotary is slowed down for lower break
> rates.
>
> Making the gap spacing wider could possibly stop
> some
> of the problems above and make the static series gap
> un-needed. With some coils, a very close gap
> spacing
> is needed to obtain steady firing. So
> experimentation
> has to be done to find the best spacing. In your
> case
> I see you tried various gap spacings, so some of the
> other
> factors above may be affecting your coil.
>
> Richard Hull used to use some resistive ballasting
> along
> with the inductive ballasting to dampen unwanted
> thumping
> and resonances in the power transformer at high
> break rates,
> with a small amount of inductive ballast.
>
> Coils with large caps running at 120 bps or so
> generally
> use larger amounts of inductive ballast, so they may
> have
> less need for a series static gap in series with the
> rotary.
>
> Regarding running 4 series rotary gaps, this also
> depends
> on many of the types of factors mentioned above,
> such
> as voltage, resonances, etc. I think Ed Wingate
> uses
> 0.020" spacing or so on his 12 point series rotary
> gap on
> his magnifier. If four rotary gaps are used, the
> spacing
> may need to be closer than when using 2 gaps. For
> my
> small coils such as the TT-42, I have to run the
> rotary gaps
> very close with just a few thousands of an inch
> spacing.
> That coil uses only two series rotary gaps.
>
> I remember Bob Svangren saying that one of his coils
> ran well with a rotary with 6 electrodes, but would
> not run
> well with 8 electrodes. I think it was because he
> had to
> slow the speed when using 8 electrodes, and it may
> have
> made the dwell time too long. This may have caused
> re-firing of the gap while the electrodes were still
> aligned
> (two firings per electrode presentation).
>
> John
>
>
> >My 10" coil used this gap:
> >
>
>http://www.hot-streamer.com/adam/bigass_coil/srsg.jpg
> >
> >modified to use a 3 phase 1725 rpm motor for
> between
> >120 and 460 bps. I've tried various rsg gap
> spacings,
> >but adding a series static sucker gap makes it run
> >very smooth. Unfortunately, my coil is so loud, I
> have
> >to limit my runtimes to several hours a week. That
> >limits my ability to make modifications and try
> them
> >out, so I'm trying to leach info from folks who
> have
> >already figured this out.
> >
> >Has anyone had any luck running all four gaps in
> >series on an ASRG similar to mine?
> >How about two sets in parallel?
> >What gap spacing are most folks running on their
> ASRG?
> >For folks running a series static gap, what type,
> >number of gaps, and total spacing have you found
> work
> >best?
>
>
>
>
>
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