Re[2]: Capacitor Size

Original poster: Illicium Verum <sebas@xxxxxxxxxxxxxxxx>


Hello Gary,

Thanks for pointing out. I to thought a static sparkgap fired always at 120 BPS.

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