Having some problems with caps....

Sparrow338, Mon Apr 23 2007, 06:18PM

For a while now I have been working on a small TC that I was going to set up as a display, kind of like what Duncan did. Using salt water caps I have found what seems to be the best capacitance for this coil, which is around 2-3 nF. So now that I have found this I was going to replace the salt waters with a 35kv 3nF cap that I have. Only problem is when I replaced it all that the coil seems to do is just arc across the main gap. Even if I widen the gap to almost the max it still just jumps it like there is no cap connected. I have tried multiple different caps in this set up and still it does the same thing... I think I'm forgetting something really obvious but I really can't find it. Here's a picture of the cap I'm using.
1177352297 661 FT0 Dsc00268
Re: Having some problems with caps....
Electroholic, Mon Apr 23 2007, 06:59PM

that does not look like a 35kv cap to me...
Re: Having some problems with caps....
..., Mon Apr 23 2007, 10:29PM

That looks a lot like a 'goldmine' (from the an online store called the eletronic goldmine) cap, which have ben proven to work very poorly in TC service. I believe the problem is that the high currents cause acking where the (presumably metalised foil) contacts the leads, so the cap goes open--which would explain the power arcing.
Re: Having some problems with caps....
Sparrow338, Tue Apr 24 2007, 02:36PM

Yep your right, it is from gold mine. Oh well I just go with an MMC then, thanks for the help.

Mods; feel free to lock this up then. smile