Re: NST cap matching

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Peter,

At 02:14 PM 1/2/2001 -0800, you wrote:
>Terry,
>      I did some experimenting last weekend, I had available a variety of
>Cap sizes for a newly aquired (used) 9-30 NST which I calculate as using
>a Res-Cap of 8.8nF, same as you. 
>
>I am using a static gap (and I'm finally using a good brass ball safety gap, 
>after ruining a 7.5-30 NST by running without a safety gap, guess I'm on the 
>"standard" learning curve!!!)
>
>I tried (with static gap)
>
>	4.8nF	(Res/2)		"zzzzzzz" fuzzy hissing sparks
>	9.6nF	(Res)		ok
>	14.4nF	(1.5*Res)	best compromise, for my taste
>	19.2nF	(2*Res)		"BBBBBBBB" sharp BANGing sparks
>
>it might be good for everyone to try these for themselves as there are great 
>subjective differences in the sparks each gave. I have a personal preference 
>for the type of sparks that the 14.4nF Cap gave me, and I will probably 
>stick with that, others will have their own preferences.

I am looking into newer MMC designs that allow very great flexibility of
the capacitance value.  Thus, making it easier for people to tune coils
however they want with just one MMC.

>
>14.4nF is pretty close to what you call "Static LTR". Did you choose that 
>based on subjective looks, or other reasons.  As long as a safety gap is 
>used, is there any reason for folks not to try this range of Cap sizes.

It is based on computer simulation, studies, and lots of work in this area.
 A summary is at:

http://hot-streamer-dot-com/TeslaCoils/Misc/NSTStudy/NSTStudy.htm

>
>
>On another note, the claim that 25" sparks should be possible with a 9-30 NST,
>does that apply to a static gap, I'm only getting about 12+" streamers. I'm
>not unhappy with that, I've finally got streamers as long as my coil is high,
>which has always been my goal, but I'm wondering if I can do it with less
>power (and still use a static gap).

My rotary sync gap 9/30 coil can easily get 25" arcs.  A static gap coil
may only get 70% of that but it all depends.  If everything else seems
right, I would carefully check the firing voltage to be sure you are firing
at the NST rated voltage and not less.  I would think you should get to 18
inches.  The rotary sync gap coils really suck every once of power out of
the NST and deliver the best performance but static gaps are a very easy
interim step.

Cheers,

	Terry


>
>
>-Pete Lawrence.
>
>
>
>	Hi All,
>
>	I made this little chart that shows what caps go with what NSTs
>
>	Transformer	Resonant(BPS)	Static LTR	Sync Rotary LTR 
>	15/60 		10.61nF (194)	15nF 		28nF 
>	15/30 		5.305nF (201)	10nF 		14nF 
>	12/30 		6.631nF (200)	9nF		17nF 
>	9/30 		8.842nF (200)	12nF 		24nF 
>
>	The LTR coils run at 120BPS and the resonant coils run at ~200BPS.
>
>	Cheers,
>
>		Terry 
>
>
>