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Help with capicators

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potatorage

Sun Apr 19 2009, 08:24PM

Registered Member #1891 Joined: Wed Dec 31 2008, 02:30AM
Location:
Posts: 21

I am planning on making a coil, but I am having troubles with capicators-- I think I need 9 nF for my 9kv 30mA coil, but the capicators that are recommended on ebay are too expensive, where can I find a suitable cost capicator?

Dalus

Sun Apr 19 2009, 08:27PM

Registered Member #639 Joined: Wed Apr 11 2007, 09:09PM
Location: The Netherlands, Herkenbosch
Posts: 512

Capacitors are expensive, don't compromise on them. Use multiple cheap capacitors to make an MMC that has the suitable voltage and C for your coil.

Btw It would be appreciated that you use a spell checker and try to show some own effort in your posts.

rp181

Sun Apr 19 2009, 08:43PM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

Are the capacitors you find on ebay one large capacitor? Tesla coil capacitors are usually made up of several small capacitors, the 942C series from CDE being the most popular and suited for tesla coil use. Make sure not to use normal lyctics, those will not work, and can result in an explosion. If you really do not have money, you can make "beer bottle capacitors". You can google those to find information.

potatorage

Mon Apr 20 2009, 01:53AM

Registered Member #1891 Joined: Wed Dec 31 2008, 02:30AM
Location:
Posts: 21

I am not planning on using one large capacitor. I looked at these

and they are $80, which is way over my budget. These are cheap, but I do not know if they are effective

Also: These seem good

rp181

Mon Apr 20 2009, 02:32AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

Those are a bit over priced. go to CDE's website, and search 942C. Find the capacitor that will work, and click the quantity, it will list some distributers. Try digikey. What is your budget?

Diarrg

Mon Apr 20 2009, 07:46PM

Registered Member #1904 Joined: Sat Jan 03 2009, 02:40AM
Location: Pittsburgh
Posts: 14

The CDE caps are decently priced. I got mine at 3.50 ish a piece, + 12 for shipping from DC Cox (If you're in the US, he'll have some for you too, probably.)

Film capacitors are terrible, and hold up very poorly under stress. And above all else, make sure you have the right voltage rating...

They are expensive, but it's worth it. I ended up paying $50 for my ten piece MMC, for a 7.5kV 30mA coil.

potatorage

Mon Apr 20 2009, 11:45PM

Registered Member #1891 Joined: Wed Dec 31 2008, 02:30AM
Location:
Posts: 21

My budget is about $30, where can I get some for cheap?

Arcstarter

Tue Apr 21 2009, 02:25AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

potatorage wrote ...

My budget is about $30, where can I get some for cheap?

You should just wait until you have the money. You might spend your whole $30 budget on some capacitors that die, and then you might get say $20-$40 again, and buy some other capacitors that die. Then your are close to what it would have costed for a good MMC!

Once you use the CDE instead of a homemade capacitor, like i did, you will never regret spending the money.

semiconductor

Tue Apr 21 2009, 04:20AM

Registered Member #1989 Joined: Fri Feb 20 2009, 05:28AM
Location: Edmonton Alberta, Canada
Posts: 17

For $30 bucks you can buy a case of beer and a roll of tin foil. If I were you I would save my pennies and invest in some good caps :)

Plasma Lover

Tue Apr 21 2009, 02:44PM

Registered Member #1911 Joined: Mon Jan 05 2009, 06:30PM
Location: Salem, Oregon, USA
Posts: 165

Beer-bottle caps are a good bet, if you can get the beer bottles cheap, but they are also very lossy, so you'll get 'unexplicably poor' results. For the same reason I disadvise beer-bottle caps, I also disadvise party-cup caps and most rolled caps, however, the classic shortened width aluminum foil and overhead transparency dielectric rolled capacitors seem to work well and, if submerged in oil, aren't very lossy.

For a first coil, if you can get beer bottles and Al foil cheap, I suggest using this, just for simplicity. Once you make an MMC of the 942C20P15K-F caps, or any other polypropylene self-healing caps, you'll respect the usefulness and the increased quality. It's almost worth the money just to have them shipped to you, ready-to-go.

By the way, if you run 9nF capacitance on your coil, it's very likely that you'll kill your transformer. I recommend running AT LEAST 11nF, since the recommended LTR (Larger Than Resonant), I believe, was 11.8nF, with TeslaMap.

If you'd like, I can help you out with your coil once you get it going. I am available via Skype and MSN messenger. If you ever need any help, I'm here. Obviously, I don't know everything, so searching the forums and even google can turn up some good answers. Just remember; when in doubt, turn to the forum. Not everything that everyone says online is as good as gold.

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