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Registered Member #1107
Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792
Im building a large coil running at 4.8kw 9kv and a resonant frequency of 109khz and according to my calculations i need at least 0.1uf of capacitence and i was thinking of going with the proven cde caps but i just dont have the funds to buy those and i was wondering if any of you know what kind of capacitor i should consider using that doesent cost as much.
edit: i searched ebay and found or so tell me if you recommend me getting one of those or if i should still keep looking.
Registered Member #1370
Joined: Mon Mar 03 2008, 09:01AM
Location: Finland
Posts: 56
I'll buy CJE caps too: They are made in China, so don't expect too high quality :). They seem OK, but dV/dt sees low. Last one has value of 130V/µs, but it is probably misspelling. Otherwise it will be totally out of tesla coil design.
Edit: note that at least my caps have identical specifications with CDE's caps. CJE is also near CDE...
Registered Member #477
Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546
teslacoolguy wrote ...
I dident even see that capacitor that is almost identical to the cde caps so i will do some calculating because thhat may be the way to go.
I think most people just assume that you can build anything with almost no $$ and have it work well. Large coils, however, do generally require some funds. Else they're no better than the junk they're made of, and dumping in more power will simply hasten their inevitable doom. Since you'll obviously be spending some serious time building a ~5kVA coil (that's a lot of careful calculation, power supply construction, gap construction, winding a big secondary, etc.), why not spend just a little more time and save up the $150 that it will cost you for the minimum order of 50 of the CDE caps from Richardson Electronics? You'd even have some leftovers that you could resell here on 4hv.org, I bet. And then you can build a nice MMC that will be worth your effort. Seriously, you should think about the big picture! It's really not worth your trouble to do all that other stuff if you're just going to do it with crap. Small coils can run on crap and survive. Big coils (and I consider ~5kVA to be darn good sized!) just won't. If you're not prepared to build a big coil using quality parts, I would recommend building something smaller.
Registered Member #1107
Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792
I sampled some caps from cde so im hoping they come and then im going to sample some more to my grandfathers address so i decided to go with those and hopefully that will cut down the cost
Registered Member #1127
Joined: Mon Nov 19 2007, 12:08AM
Location:
Posts: 139
I'd go with heavy duty 1600 VDC 0.68 uF CDE caps. These guys are great with high current discharges and I've pushed these caps at 2 times DC rating without a single cap faliure. Yep... they are $4.25 each ... but hell.. if you want power here is how you do it. Go with Richardson Electronic.... and order in a big amount!
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best capacitor for the coil im building
no just kidding give it some more time before giving up all hope because hey after all they are doing you a favor 
.
