Re: spark gap

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Just Justin <rocketfuel@xxxxxxxxxxxxx>



Sorry, you're right.  I forgot to mention that the spark gap should be
the only thing connected to the NST when using this method!

That is what I meant by it being a similar process to setting the safety gap.


Maybe I should go back to asking instead of answering...


Justin



> Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>
>
> Ouch!  The suggested method of setting the spark gap width is a
> sure-fire way to kill an NST.  Yes, the performance will be very good -
> the wider the gap, the better.  But the voltage may far exceed what the
> NST and cap can withstand.
>
> The correct way to set the gap width is to disconnect the primary tap,
> so that the gap is across the NST output and the cap/primary are
> effectively out of the circuit.  The gap width must be set so that it
> just begins to fire with maximum Variac AC in to the NST.
>
> With a 12/120 power supply, attention to airflow through the gap is
> vital.  With that much power, more than a gentle wafting through the gap
> is needed to keep it cool.
>
> Regards, Gary Lau
> MA, USA
>
>
>  > Original poster: Just Justin <rocketfuel@xxxxxxxxxxxxx>
>  >
>  >
>  > Hi Tim,
>  >
>  > My coil is similar in specs, although only 60mA instead of 120.
>  >
>  > I found that I've had the best luck with 2 gaps out of 6 available.
>  > The way I set them is similar to setting a safety gap: open the gap
>  > until they stop firing and then close it back just a wee bit.  (For
>  > the safety gap you would keep it at the just-barely-not-firing
>  > distance).
>  >
>  > The width of the gap will determine the voltage that the tank cap
>  > is charged to before discharging through the spark gap.  In my
>  > (limited) experience, a wider gap makes loud bangs that are 'hotter'
>  > and more randomly distributed.  A narrower gap makes more of a
>  > high pitched buzz as the breakdown frequency goes up (the tank cap
>  > can be charged to the breakdown voltage several times in 1/2 of a
>  > 60Hz AC cycle).  Also with the narrower gap, I tend to get a streamer
>  > that stays 'solid', and wanders around rather than the random sparks
>  > jumping around erratically.
>  >
>  > My gap pieces are approx 1"x6" copper pipe and they seem to stay cool
>  > with a microwave-sourced fan blowing out the sparks.
>  >
>  > I also found that I got much better results with a 6" minor diameter
>  > toroid, perhaps you would as well.
>  >
>  > happy coiling,
>  >
>  > Justin
>  >
>  >
>  >
>  > On Thu, Jan 19, 2006 at 11:35:13AM -0700, Tesla list wrote:
>  >  > Original poster: Timjroche@xxxxxxx
>  >  >
>  >  > I'm running:
>  >  > 12kV 120mA NST
>  >  > .03 uF 45kV maxwell tank cap
>  >  > 12 T .25" tube .25" spacing primary
>  >  > 4.343" OD 28awg 17" lng secondary
>  >  > maj. dia 17" min dia 4" toriod
>  >  >
>  >  > What is the best place to start a static gap?  I have . 5" solid Cu
>  >  > (12 pcs. 4" long), .5" tube, 7/8" tube, and 1.125" tube...is hollow
>  >  > better? bigger dia?
>  >  > What about length? my 7/8" (6 pcs. 6" long) better than .5" 3"long?
>  >  > can you have to many gaps? i.e. total gap=.5",  2 tubes?, 6
>  > tubes?, 12 tubes?
>  >  >
>  >  > thanxs
>  >  > Tim
>  >  >
>  >
>