[Home][2017 Index] Re: [TCML] First coil [Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [TCML] First coil

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 Hickman
Stoneridge Engineering LLC
+1 630-964-2699
World's source for "Captured Lightning" Lichtenberg Figure sculptures,
magnetically "shrunken" coins, and scarce/out of print technical books

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

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.


Tesla mailing list

Tesla mailing list