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Re: [TCML] Strike Rail Hits Was: Stacking vs Large Diameter
Bart,
That's some interesting observations that I never really
considered. Not too sure my observations have matched
the certain "power window" that you state where the pri-
mary strike frequency seems to spike. As you stated,
when the sparks are allowed to emanate freely from the
smooth (or relatively smooth) toroid surface, they tend
to start from the horizontal center region. With this in mind,
I have found that the primary/strike rail hits can be
significantly reduced by setting a breakout point closer to
the top of the toroid, thus forcing spark propagation
from the upper part of the toroid, well above the hori-
zontal center. But even then, I will still get an occasional
strike to the primary region. I guess you have to expect
that with a 240 volt, 90 amp power feed into a coil
that doesn't quite top 8 ft. in total vertical height!
This past Friday when P. Slawinski and C. Prince
came for a visit, we tried elevating the whole tank
circuit assembly of the Green Monster about 18"
with my 4 jack stands. This is what allowed for more
numerous sparks in the >12 ft. range, in my opinion,
although this did NOT change the toroid to primary
coil/strike ring clearance and consequently, the pri-
mary strike frequency remained pretty much status
quo.
David Rieben
----- Original Message -----
From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, July 15, 2008 8:51 PM
Subject: Re: [TCML] Strike Rail Hits Was: Stacking vs Large Diameter
Hi David,
I've used my old primary on many coils and refitted it with inner turns
as necessary (started big and then started building smaller coils). I
was just thinking the Green Monster would look pretty cool with a small
ribbon primary resonantly driving the secondary. Yes, the sparks do go
where they want. But then, their going there for reason (because they
can) ;-) . What I don't like is giving the coil "just enough power" to
hit the primary. I have some extra turns and thus a little
auto-transformer action occurring which I don't like. This seems to add
to primary hits, but I'm not sure if it's the auto-transformer action or
simply power. A smaller 4.5" coil I run can hit the primary as well all
day long if I only give it just about enough juice to do so. But if I
increase power enough, I rarely hit the primary. I can also reduce power
and achieve the same thing of course (but that's no fun).
I think some coils will hit the primary quite often and some won't. Some
coils are geared up just enough to do so and no more. Sparks start in
the horizontal center of the toroid as we all know. It always starts out
horizontal (or say emitting directly outward from it's origin). After
the spark begins it's length increase, then it begins to bend. With
higher power, it seems that initial thrust outward heads out far enough
to stay away from the primary or whatever. But with just the right
power, it can bend right down and then there's the primary or strike
ring willing and ready to accept the connection. The spark "should"
actually head upward due to heating. And at first it does, but then the
fields overtake the heating affect and drive the spark downward as the
spark progresses further from it's origin. Easy to see in just about
everyone's spark photo's (from big coil to little coil).
As coilers start increasing power to attain longer sparks, they
eventually cross the primary strike bridge. Coilers may wonder why (did
they do something wrong, did tuning go south, what happened?). Well,
they simply reached that threshold. It's time to boost power further to
get over the hurtle (or reduce power, or even maybe change the top load
height and/or size).
Take care,
Bart
David Rieben wrote:
Hi Bart,
Cameron Prince uses a flat ribbon primay design
for his primary on his big coil, too. It would have
been easier for me to employ the flat ribbon if I
had started the design with a flat ribbon primary to begin with, as
"retroing" from a copper tube
design back to a flat ribbon design would pret-
ty much require a complete dismantle and reas-
sembly of the system. It's funny too, because sometimes I can hurl
multiple streamers for
a minute or so non-stop without hardly a single primary primary strike
and then the
next 30 seconds the streamers may hit the
primary area 30% of the time! They seem to
do what they want to do ;^)
David Rieben
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