[Prev][Next][Index][Thread]
Re: New System, was "Real Data--
Hi Chuck,
If you have 0.1uF on hand with some other caps, I would
love to hear the results of a performance comparison. Sounds like
you'll need some more primary inductance though.
Malcolm
> Right now I am trying to sort through several alternatives associated
> with my winter project. Yes, it is a two coil system and I have a 10
> KVA 14,400 VAC pole pig, welder ballast and Superior 1256D variable
> transformer in the supply. Last night I decided to change the secondary
> to a 56" length with the 15.25" form diameter in order to get a bit
> lower in frequency. This results in a resonance of about 106 Khz
> without a toroid. My curiosity at this point centers about picking the
> optimum capacitor size, with maximum spark being the goal. I originally
> thought a .1 mfd cap would be about in the correct range, but alot
> depends on how far the secondary resonance will drop with a proper
> toroid, if an ideal L/C ratio is a target. I'm still not clear on what
> the proper L/C ratio might be. My 8" diameter by 28" long coil had a
> 221 Khz resonance and with the 48" toroid it dropped to a measured 94
> Khz. If I could expect the 106 Khz resonance of the new secondary to
> drop to around 50-55 Khz with a big toroid, I would have a primary
> needing about 100 uh with the .1 mfd cap. O.K., I guess I could just
> slap a random choice cap size in there and hope for the best, but
> another option makes more sense to me. That option is, we have a
> tremendous amount of experience in this group and I sure don't mind
> listening for a few weeks and filtering out the stuff that will help me
> get a notch closer to the best I can personally do (The real story is, I
> sure don't want to spend $450-$600 on a cap that isn't quite right!).
> My last primary had 15 turns so I have no problem with a similar design
> here. I will use 5/8" thin wall copper refrigeration tube, if they make
> it in that size! Haven't checked yet.
<snips>