Re: ARSG Questions

["Tesla list" <tesla@xxxxxxxxxx>]

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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