Re: Re[2]: Capacitor Size

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>



It's done with the setting (distance) of the 
spark gap itself.  It is adjusted such that the 
gap can only fire when the AC waveform hits its 
plus and minus peaks, thus insuring it fires at 
120 pps.  We usually use 7-8 5/8 inch dia. tubes 
with a total gap setting of 0.310 inch (divide 
this by the number of gaps in your system).  We 
use a 90 cfm fan to blow thru the 6 inch ID PVC 
tube.  This works fine up to 120 ma.

If the gap is set too close together it could 
re-fire more than 120 times per sec but this is uncommon.

Dr. Resonance


Is there a formula to calculate the BPS of a SSG?


I'm curious, what speed did you measure?

Best regards,

Sebas.


Thursday, October 6, 2005, 10:08:55 PM, you wrote:


> Original poster: "Lau, Gary" <<mailto:Gary.Lau@xxxxxx>Gary.Lau@xxxxxx>


> Hi DC:


> I assume you meant to say "0.016 at 60 mA".


> Have you actually scoped a coil with a static gap

> that operates at 120 BPS? Every static gap coil

> that I've scoped ran at a far higher rate than

> that.  I probably could have achieved 120

> (chaotic average) BPS, but I would have had to

> open the gap to an unsafe setting.  Since I tend

> to use a 2X mains-resonant cap size, I would see

> an even higher BPS had I used a 1.57X cap.


> In my early naïve days of coiling I thought that

> 120 BPS was the natural and normal mode of

> operation for a static gap.  I know better now

> and don't wish to perpetuate that misunderstanding.


> Regards, Gary Lau

> MA, USA



 >> Original poster: "D.C. Cox"
<<mailto:resonance@xxxxxxxxxx>resonance@xxxxxxxxxx>





 >> Erms resonant value times 1.57 for best effective C value.  With 30

 >> mA its near .008 and doubles to 0.16 at 60 mA.  This works best with

 >> a static copper tube sparkgap firing 120 pps.


 >> Dr. Resonance





 >> >Original poster: "Lau, Gary" <<mailto:Gary.Lau@xxxxxx>Gary.Lau@xxxxxx>

 >> >

 >> >The mains-resonant cap value for a 15/30 NST with 60 Hz power is

 >> >.0053uF.  It was once thought that this would hit a performance

 >> >sweet-spot, but I don't think this is so.  Non-linear behavior

 >> >(ferroresonance) of the NST core makes the mains-resonant cap value a

 >> >moving target.

 >> >

 >> >The rage these days is to use a Larger Than (mains) Resonant cap value.

 >> >The calculated mains-resonant value multiplied by the square root of 2

 >> >(or was it 3?) is often cited as the optimum value.  Personally, I've

 >> >found that 2X the mains-resonant value works well.  I doubt there's any

 >> >kind of sharp sweet spot, so any of these factors will all work.

 >> >

 >> >One thing that is clear is that streamer length is proportional to bang

 >> >size.  So if your static gap fixes the bang voltage, you can get a

 >> >bigger bang and longer streamers at a reduced bang interval by using a

 >> >bigger cap.  But if your wife favors your existing cap, you might get a

 >> >bigger ba...  OK, I'll stop there.  Always a compromise...

 >> >

 >> >Regards, Gary Lau

 >> >MA, USA

 >> >

 >> >

 >> >

 >> > > Original poster: "Dirk Stubbs"
<<mailto:dirk@xxxxxxxxxxxxxx>dirk@xxxxxxxxxxxxxx>

 >> > >

 >> > > I have a question about sizing of a capacitor. My power supply is a

 >> > > NST 15kV at 30mA. I originally planned on using 10 doorknob

 >> > > capacitors which are rated at 30kV with 0.006 uF total(each was 620

 >> > > pF). However I have a question about the needed capacitance for my

 >> > > TC. Most of the references such as websites  and calculators said

 >> > > that I need .0053 but I see people saying you need .008-.009 uF.

 >> > >

 >> > > What size is correct?

 >> > >

 >> > >

 >> > > What will happen if I use my current capacitor setup?

 >> > >

 >> > >

 >> > >

 >> > > I would like to use my current setup to save money. The wife has

 >> > > about had it with the TC as it is . J

 >> > >

 >> > >

 >> > >

 >> > >

 >> > > Thanks,

 >> > > Dirk

 >> > >

 >> > > -

 >> > >

 >> >

 >> >


 >>






--

Best regards,

Sebastiaan