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Re: Rotaty popping, (Was Re: commercial cap failure)



> Original Poster: "D&M's High Voltage" <dmshv.davmckin-at-gte-dot-net>

David,

> Are you putting the resistors in parallel with the inductive ballast?
> If so, try putting around 0.25-0.5 ohms in series with the ballast and
> see if you still have the same problem.  This will help take out some
> of the inductive kick and produce a smoother running coil.

Yes, I'm switching 1000W heater elements in parallel with the welder. To
reiterate, my coil runs plenty smooth and I have only heard the "car door
slamming" sound a few times. Maybe I'm overly concerned, or maybe it was a
car door slamming. When I heard this sound there were no other "hiccups"
with the coil.


> The Jacobs ladder works better because you need raw current for it to
> produce longer, hotter sparks.  On the lower current setting of the
welder,
> you have less turns (lower voltage) and less inductance or current
limiting
> capability.  This is in some contrast to the tesla coil that needs a
certain
> amount of inductance (to limit the current through the transformer) to
> enable the gap to quench.  If you don't have enough inductance on the
> primary side of the transformer, the gap won't quench well.  In this
> case (same as when you try it on the high current side of the
transformer),
> you will have what I called "arc follow".  Arc follow is where the rotary
> gap
> doesn't quench, and the arcs follow the contacts as they spin around.
I've
> seen arcs follow the contacts for about 1/4-1/3 of a revolution on the
> rotary
> disk.  When you have arc follow, the performance of the coil will greatly
> diminish.

Ok, good so far.


> A safety gap across the rotary is a good idea.  The series ballast
> resistors will aide in reducing the inductive kick and produce a
> smoother running system.


> I'm speculating that the popping is coming from a reignition of the arc on
> the rotary spark gap (as I'm interpreting that you presently don't have
any
> safety gaps across either the capacitor or the rotary gap).  If you don't
> already have one, try a series (in series with your rotary gap) static gap
> using a vacuum cleaner motor.  Also, put the arc through one side of the
> disk (through one set of contacts) and then out the other side.  This will
> give you 4 "dynamic" gaps + your additional series vacuum static gap.
This
> would quench the rotary very well and should give you a really good
> performing coil.

I had previously tried an air blown static gap in series with my SRSG,
didn't seem to change anything. (Still worth another test tho, I could have
easily overlooked something). I do have 4 "dynamic" gaps on my SRSG.

Lots of good ideas here, David. You have given me some things to think about
and to try.

Regards,
Jon Rosenstiel