Re: A new mini-coil competition winner!

```Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Karl,

I see what is going on 8-)

If we model your coil with MicroSim:

http://hot-streamer.com/temp/Karl1.gif

We get this:

http://hot-streamer.com/temp/Karl2.gif

```
If the component values are shifted a tiny bit we basically get the coil firing twice on each peak of the sine wave from the transformer. So it fires at both 5.5 and 8.3mS That doubles the streamer power. So you are closer to 78W in.
```
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If it were 120BPS the new ScanTesla gives 9.7 inch streamers. So your double firing almost double the spark length!!!! Normally I would expect it to increase SQRT(2) or 13.7 inches with doubling power. ScanTesla does not do double firing so we have to guess a bit and I am not sure the function of double firing to streamer length is well understood (a DRSSTC thing).
```
This brings the Freau number down to 2.06 which makes more sense :-))

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It is hard to know what Rprimary is for your coil since it is significantly different that what we are used to. But I am sure an SISG even with double firing will further increase the arc distance significantly. I am not sure how much though.
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Cheers,

Terry

```
```Hi Karl,

Wow!!!

The coil power is:

1/2 x 25nF x 5090^2 x 120BPS = 38.86W

If 18.125 = F x SQRT(38.86)  Then F = 2.91!!

But if we do the regular Freau equation:

1.7 x SQRT (0.038 x 5090) =  23.64 inches...

So something is going on "I" don't understand.  Let me think on it %:-)

Cheers,

Terry

At 04:45 PM 6/6/2006, you wrote:
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```Hi Terry,

```
I tried your test to make sure my gap did not widen from when I set it at 0.06" a few weeks ago. I built the primary section first, and that test was one of the first I did then to accurately set the gap. The gap fires smoothly with just the NST across it at a variac setting of 90% which is 108 VAC into the NST. That should correspond to an output voltage of approximately 5090 VAC peak. It does not look as if my gap is set too wide. One of the rules of Gary's competition states that you may not run with a wide open gap. I was careful to follow those rules to the letter in order to qualify, and to protect my little NST.
```
Also, did you see any reason ScanTesla predicted only 6.4" streamers?
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My earlier post contained the input and and output files I used in the program.
```
Karl

On Jun 6, 2006, at 5:38 PM, Tesla list wrote:

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```Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Karl,

The resonant capacitor value for the modified transformer is:

Cres = 0.038 / (2 x pi x 60 x 4000)  =  25.2nF

```
so the 25nF capacitor in the coil is right at resonance. Just like an NST system, the voltage at the gap can be pretty high and well over the rated voltage with a resonant size cap. So instead of the firing voltage being 5524V it might be much higher. I suspect it is closer to 15kV!
```
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There is an easy way to check. Disconnect the cap and primary coil so "only" the transformer and gap are in circuit. With just the gap as the load for the transformer, it should put out its rated voltage.
```Then see if the gap fires.  If it does, then the gap is set to 5524.
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However, if the gap does not fire and the electrodes need to be moved closer, then the gap was set for a higher voltage. Once the gap is set for 5524V I think the spark length will go way down :-( Like 7 to 10 inches. So set the gap back to where it was :-))
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Cheers,

Terry
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```

```