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teslacoolguy

Thu May 15 2008, 04:39PM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

hey guys i found this

and i thought it was a good buy until i read that one of them has a small leak in it. I was wondering if that Would effect the proformance of the capacitor any?

J. Aaron Holmes

Thu May 15 2008, 05:57PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

For a Tesla coil? If so: The real trick is never the capacity or the voltage, it's the pulse discharge characteristics: Peak and RMS current ratings, % voltage reversal rating, etc. In most cases, these characteristics are not printed on the product, but are instead available only as documentation from the manufacturer. In lieu of that, I would never even consider buying them. Life's too short to waste on blowing up the wrong kind of capacitors.

Also, caps encased in metal or glass would never be my first choice for a Tesla coil cap (here again, assuming that's your intended application). If the caps "blow up", then you've got metal or glass fragments flying everywhere. I've been standing only a few feet away from a metal cap (pulse-rated, too!) that inflated like a balloon due to internal arcing while being used in a friend's Tesla coil. A 12' geyser of oil sprayed out from around the ceramic bushing and we all ran for our lives! By comparison, I've had Maxwell pulse caps "blow up", and the expoxied-on ends just pop off with a thud. No flying debris. I suppose it's possible to rig up a scenario where one would truly detonate, but that seems unlikely in Tesla use unless extreme neglegence is involved.

...and if not for TC use, then what? Impossible to say whether a cap is ok or not without knowing what it's for.

Cheers,
Aaron, N7OE

teslacoolguy

Thu May 15 2008, 06:27PM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

No actually it is not going to be used for a tesla coil but for a future can crusher that i was planning to build. Trust me i found out that these are not meant for tesla coils the hard way

Shaun

Thu May 15 2008, 06:56PM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

Its funny that the item location is supposedly Colorado Springs

Mathias

Thu May 15 2008, 06:57PM

Registered Member #1381 Joined: Fri Mar 07 2008, 05:24PM
Location: Hungary
Posts: 74

if you really want to use just a few(1-2) caps instead of a whole bank of caps , then as posted before me (you cant really tell this enough times:P) for not just test purposes (then most descently made homebrew will do) but for long term use you need high quality stuff that can withstand tc abuse for prolonged time ,

btw maxwell pulsed caps ,i think i read it somewhere on one at the lab that those can't really handle more then 40% of the rated voltage in reserve (we use those in the marx) and these are not "cheap"

in my option, your best chances are with a mmc made with some nice caps , if you build one thats large enough it wont get warm even at around 1x kVA

edit: doh this post took too long ,anway im not gonna rewrite it :P

teslacoolguy

Thu May 15 2008, 07:04PM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

I sead that i am not going to be using them in a tesla coil but in a future can crusher.

J. Aaron Holmes

Thu May 15 2008, 07:32PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

teslacoolguy wrote ...

I sead that i am not going to be using them in a tesla coil but in a future can crusher.

Keep an eye out for some of those Aerovox or Maxwell "energy storage" capacitors like TDU has. E.g., 200+uF @ 10+kV. They weigh a few hundred pounds, so local is good! Watch out for PCBs. They go by on eBay periodically for pretty cheap, too (couple of $100 versus a couple of $1k new). They're not really meant for pulse discharge and their lives will be significantly shortened as a result, however since you're not going to be crushing hundreds of cans per second, you'll never know or care

Hhhhhhhhh

Fri May 16 2008, 08:30AM

Registered Member #1340 Joined: Thu Feb 21 2008, 12:47AM
Location:
Posts: 23

Yes if the oil leaks out the cap will go bad sooner, and more then likely it is leaking becuse it is bad. that is what i've seen with caps ive used.

a pic of some oil filled caps

big DC caps sounds like that could be painful

Dragon64

Sat May 17 2008, 02:40AM

Registered Member #1438 Joined: Sat Apr 12 2008, 12:57AM
Location: Canada
Posts: 218

Another quick question, hopefully not too OT.
One of my MOC got damaged on the lid of the metal can. The oil insided it started to drip out slowly. I epoxyed the end but im a bit worried with running my resonant MOT with it.

Also, wonder if the oil is toxic. It did say that there are no PCB.

Arcstarter

Sat May 17 2008, 04:57AM

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

hydraliskdragon wrote ...

Another quick question, hopefully not too OT.
One of my MOC got damaged on the lid of the metal can. The oil insided it started to drip out slowly. I epoxyed the end but im a bit worried with running my resonant MOT with it.

Also, wonder if the oil is toxic. It did say that there are no PCB.

Well if the oil is non toxic it is probably not toxic if touched, but if you were to chug it you will probably wake up with electrodes all over you

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