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Re: [TCML] First coil

Hi Terry,

I'm thinking that if the toroid size is too big, it won't break out without
the barb.  Perhaps a few more details of your coil will make for a clearer
picture.  Power source, gap details, cap size, and most importantly, toroid
size?  With toroids, bigger is usually better, at least as far as getting
the longest possible streamer from a breakout point, but if you're shooting
for sparks without a breakout point, a smaller toroid may be necessary.

Regards, Gary Lau


On Sun, Oct 29, 2017 at 12:25 AM, Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx>

> Hi Terry,
> Racing sparks typically occur when energy is being injected into the
> secondary too quickly. Although this is _usually_ caused by
> excessively-high coupling, it can also occur when the bang size is too
> large for the size of your secondary, or if your system is significantly
> out of tune. To solve the problem(s), you'll need to first insure that your
> system is in tune, that P:S coupling is not excessive, and that your toroid
> is appropriately sized for your system's peak output voltage.
> 1. Tuning:
> I'd suggest initially running the system with a breakout point (or barb)
> during this phase. Reduce the primary spark gap length to reduce maximum
> bang size. Experiment with primary tap point until you get the maximum
> secondary spark length at a given variac setting. The system should be
> smooth running with consistent spark length under continued operation.
> 2. Coupling:
> If you don't see any racing sparks, slowly increase the "bang size" by
> widening the main gap slightly. Don't increase gap length beyond the point
> where the safety gaps begins firing or if you start to see racing sparks.
> If you see racing sparks, reduce coupling slightly and continue the process
> of increasing the main gap length until you can run at full power with no
> evidence of racing sparks. You may need to retune the primary a bit by
> increasing primary inductance slightly (i.e., moving the primary tap
> outwards 1/8 - 1/4 turn) to compensate for capacitive loading of longer
> secondary streamers. Any signs of racing sparks mean that you need to
> further decrease coupling.
> 3. Final tweaking:
> Reduce the length of the breakout point/bump to see if the coil can
> self-break from the toroid as you approach full power without introducing
> any racing sparks. Further decrease coupling if you see any evidence of
> racing sparks. Ideally, an appropriately-sized toroid will self-breakout
> before you reach full power. Failure to self-breakout can occur if the
> minor toroid diameter is too large (requiring excessively-high breakout
> voltage) or if the major toroid diameter (and capacitance) is too large,
> which reduces maximum topload voltage below the point of self-breakout. For
> this case you may need to operate your system with a breakout bump or point
> to insure breakout. Even with an optimal setup, you may still need to use a
> breakout point during humid weather when it's significantly more difficult
> to initiate breakout.
> Good luck,
> Bert
> --
> Bert Hickman
> Stoneridge Engineering LLC
> http://www.capturedlightning.com
> +1 630-964-2699
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> Terry Oxandale wrote:
>> It's been a long time since I was more active on this list. I never was a
>> "technical" enthusiast, so being I've had the coil in storage for probably
>> 10 years, and have forgotten more than I remember about coiling. I'd like
>> to
>> tap the group for some help or advice please.
>> My coil appears to operate as I remember it did, as long as I've got a
>> sharp
>> pointed barb sticking out the side of the toroid to promote a discharge.
>> When I remove the barb to get a normal toroial discharge, I get racing
>> sparks along the secondary, and nothing out of the toroid, all for the
>> same
>> power setting as the "barbed" setup (2kva). Thus I separated the secondary
>> from the primary in terms of vertical distance to lower any excessive
>> coupling (shooting in the dark here), but still racing arcs along the
>> secondary.
>> Any ideas on the huge difference (or lack of performance) between "barbed"
>> and "non-barbed? No component changes have been made since a decade ago
>> when
>> it all worked great, and both configurations performing equally well.
>> Terry
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