Re: Safety gap issues

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Jason,

I think the equation:

Vt = Vf x SQRT (Cp / (2 x Cs))

Will give you a real good answer.  However, we are not real sure of 
what the firing voltage at the gap is.  It really could be in the 
range of 5 to 20kV!

Perhaps you could set two "needle" points up to measure that 
voltage.  Just two sharpened long (~3 inch nails) across the spark 
gap.  As you move the points closer together, there will be a point 
where they start to arc.  Then the chart at:

http://hot-streamer.com/TeslaCoils/Misc/SGapVolt.jpg

could be used for needle point gaps.  Keep other objects away from 
the area of the gap so as not to mess up the fields there.  If you 
could get within a mm or 1/2 a mm, that would give us a good solid 
measurement of the firing voltage.  Then, the top equation should work fine.

Cheers,

        Terry

At 11:18 PM 11/27/2005, you wrote:
> First of all, Terry, I am asking so many questions, and receiving 
> such an overwhelming amount response from your list- I swear I cant 
> remember everything you guys tell me.
>
> *thus, forgive me if I ever ask something twice
> *Dr. Resonance tells me 150KV max
> *You tell me 304 Max, and 116KV max?
> *my equation uses tell me 117KV output max
>
> Which answer do I use??????
>
> Perhaps if I had more primary tap, I could add a larger toroid, 
> which would increase voltage output overall??
>
>
> > From: "Tesla list" <tesla@xxxxxxxxxx>
> > To: tesla@xxxxxxxxxx
> > Subject: Re: Safety gap issues
> > Date: Sun, 27 Nov 2005 19:00:20 -0700
> >
> > Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
> >
> > Hi Jason,
> >
> > At 03:55 PM 11/27/2005, you wrote:
> > > YOU SAID:
> > > "A very good equation that works well to find a coils peak output 
> > > voltage is:
> > >
> > > Vt = Vf x SQRT (Cp / (2 x Cs))
> > >
> > > Where:
> > >
> > > Vt it the peak top voltage
> > > Vf is the spark gap firing voltage
> > > Cp is the primary capacitance
> > > Cs is the effective secondary capacitance
> > > SQRT square root function "
> > >
> > > * if i know the distance, can you tell me the sparkgap firing 
> > > voltage? it is 7.5 to 8 mm, at 30MA. 8000v?
> >
> > Hmmm...  I think you are using copper pipes in your spark gap so we 
> > will just assume they are about 2.5cm in diameter and use that data 
> > from this chart:
> >
> > Hmmm... That gives 25 kV peak which sound way to high for your 
> > 12000V NST...  It would normally be about 12000 x SQRT(2) = 
> > 17kV.  But your primary cap is near resonant so maybe you are 
> > getting a bit more...  Hard to say without a high voltage probe and 
> > all...  Lets just average the two ;-)
> >
> > (25 + 17) / 2 = 21kV  That is probably as close of guess as we can 
> > make from here.  So your coil is firing at about 21kV as far as we can guess...
> >
> >
> >
> > > * primary capacitance? you mean just the capacitor? 7.8nF (.0078 uF)
> >
> > Yes.
> >
> > > * secondary capacitance, with toroid, is 18.6 pF (.0000186 uF)
> > >
> > > wtf? that means my coil only makes 117.3KV!!!!?   Cant be true. I 
> > > wont buy it
> >
> > Vt = Vf x SQRT(Cp/2Cs) = 21000 x SQRT(7.8e-9 / (2 x 18.6e-12)) = 
> > 304kVpeak.  that is probably pretty close.  If everything we 
> > exactly perfect, that would give about 32 inch streamers.  I think 
> > you said that yours are about 16 inches so maybe something is not perfect.
> >
> > You mentioned 8000 volts for Vf.  That would give:
> >
> > 8000 x SQRT(7.8e-9 / (2 x 18.6e-12)) = 116kVpeak and about 20 
> > inches in a perfect system.  It is possible the firing voltage is 
> > rather low but I would be super careful about trying to raise 
> > it.  If something else is wrong, raising the firing voltage might 
> > blow the NST up...
> >
> > Most Tesla coils run in the 250 to 500kV peak range.  There are a 
> > few coils that get past 1 million voltage but they are vary 
> > rare.  Here is one a little under 2,000,000 volts ;-)
> >
> > http://www.lod.org/Projects/electrum/testing/pages/Levine23pwr.html
> >
> > http://www.lod.org/Projects/electrum/index.htm
> >
> > It is 38 feet tall!!!
> >
> > Cheers,
> >
> >         Terry
> >
> >
> >
> > > > From: "Tesla list" <tesla@xxxxxxxxxx>
> > > > To: tesla@xxxxxxxxxx
> > > > Subject: Re: Safety gap issues
> > > > Date: Sun, 27 Nov 2005 10:02:21 -0700
> > > >
> > > > Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
> > > >
> > > > Hi,
> > > >
> > > > A very good equation that works well to find a coils peak output 
> > > > voltage is:
> > > >
> > > > Vt = Vf x SQRT (Cp / (2 x Cs))
> > > >
> > > > Where:
> > > >
> > > > Vt it the peak top voltage
> > > > Vf is the spark gap firing voltage
> > > > Cp is the primary capacitance
> > > > Cs is the effective secondary capacitance
> > > > SQRT square root function
> > > >
> > > > This assumes the coil is well tuned and running well without any problems.
> > > > As far as I could ever tell, the size of the toroid really does 
> > > > not affect voltage that much.  But larger toroids do have larger streamers.
> > > > I think that is do more to electrostatic field effects rather 
> > > > than higher voltages.
> > > >
> > > > Cheers,
> > > >
> > > >         Terry
>
> _________________________________________________________________
> Don't just search. Find. Check out the new MSN Search! 
> http://search.msn.click-url.com/go/onm00200636ave/direct/01/