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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


----- Original Message ----- From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Monday, July 14, 2008 9:13 PM
Subject: [TCML] Strike Rail Hits Was: Stacking vs Large Diameter


Hi David,

I'm in the process of building a ribbon primary. The ribbon is 1" x .035" x 50ft. I'm building this for the SISG coil (since I'm waiting on more diodes as I decided on full bridge capable of 60kV rectification). The inner diameter to outer diameter thickness will only be 3.5 inches. I plan to use fiberglass runners and Plexiglas ring over the top of the ribbon to further prevent those unwanted hits. This will make for a very compact primary. My reasoning here is that I simply don't want primary hits with an SISG coil, so I'm doing this to further eliminate the possibility.

Something like this might be really good (and cool) for the Green Monster 8-) . Remember Bill Wysocks Griffith Park Observatory coil? Or the Mini-GTO? http://www.ttr.com/Fry-coil.htm. 5th picture down shows a closeup of the primary. I think this is the same ribbon I have.

I've gone through some pics of ribbon primary construction, and of all I've seen, a simple standoff like what Bill used seems to be the best solution in my book. I tried the insertion between turns using various things like 1" foam, rubber, etc., but I've come to a conclusion that simple standoffs like Bill used is better for cosmetics, reuse, etc. It takes a little more work to cut the standoffs, but to me it's worth it.

Anyway, just thinking that the Green Monster might benefit from such a primary?

Take care,
Bart



David Rieben wrote:
Hi Phillip,

Well, you've seen firsthand what can be done with single large
diametered toroids in both the big coils of Cameron Prince and
myself ;^) There are a lot of variables to consider that would
make it nearly impossilbe to give you a definitive "yes or no"
answer to your question. The main advantage that many taught
with the double stack toroid design is the better E field protec-
tion for the reduction of primary/strike rail hits. I might could
personally reduce some of the strike rail hits from my Green
Monster coil by installing a smaller "bottom toroid" underneath
the large main unit, although it starts to become nearly impossible
to completely eliminate primary/strike rail hits at these power
levels with the physical size limitations that I am dealing with.

--
David Rieben
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