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Re: [TCML] TC Newbie
I too have built glass jar capacitors.
They are lossy with AC voltage and, yes they do heat up.
I would use the bottle capacitor for short runs.
The Ozone created by the charged air around the plates results in breakdown of the dielectric~glass.
I have had a large battery of jars fail after about 2 weeks in service. They usually overarc and shatter. These were clear pyrex glass containers.
Don't expect a lot of life from these. Performance is poor.
I'd be running these DC if I were you, and even then be careful.
There is NO compairison between this and CDE 942K capacitors! The performance is like compairing a bicycle and a rolls royce.
----- Original Message -----
From: Matt <tonedeafmessiah@xxxxxxxxx>
Date: Friday, December 5, 2008 9:21 am
Subject: Re: [TCML] TC Newbie
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Gregory;
>
> Thank you very much for a both informative and entertaining run
> down on a
> subject that I have found eye-crossingly confusing to research!
>
> Will be embarking on the construction of my coils and spark gap
> tomorrow, so
> hopefully I will be posting results. I constructed a jacobs
> ladder to
> demonstrate my new obit and managed to give myself a good shock
> through a
> housebrick I was using to hold the antennae up. I think there
> must have been
> moisture in the brick - needless to say marigolds and a healthy
> dollop of
> safety awareness will be applied from now on!
>
> I'll be sure to check your site,
>
> -Matt
>
> On Thu, Dec 4, 2008 at 11:26 PM, G Hunter
> <dogbrain_39560@xxxxxxxxx> wrote:
>
> > Hi Matt,
> >
> > There's a lot of mythology out there concerning bottle
> capacitors. Most of
> > it conflicts so badly with my own experience that I can only
> conclude they
> > are tall tales. For example:
> >
> > 1) Beer bottles quickly overheat in Tesla coil service
> and often crack.
> >
> > A) I've built and used over 100 beer and wine bottle
> caps, and I NEVER had
> > one fail in Tesla coil service, even at powers of up to 7200VA
> and at NST
> > voltages of up to 15kvac. I've also never had one warm
> up above room
> > temperature. Never had a leak either--not a drop.
> >
> > 2) Bottle caps are lossy and inefficient, and shorten
> your sparks.
> >
> > A) I won't argue with this one. I've not measured
> it myself, but expert
> > coilers assure me that plastic film pulse caps outperform
> glass caps by a
> > mile and a half. I have no reason to doubt them.
> It may depend on what
> > kind of bottles are used, as not all glass is created
> equal. No doubt some
> > formulations of glass have better RF properties than
> others. Cap bank
> > configuration probably matters too. A large number of
> small bottles wired
> > in parallel is probably more efficient than a few large
> ones. Having said
> > all that, I've been very satisfied with the sparks I generated
> on a
> > beer-bottle budget! Giving up a couple of inches of
> spark length to save
> > L50-L100 on capacitors seems like a pretty good deal.
> >
> > 3) Bottle caps sometimes burst while the Tesla coil is
> running. In fact,
> > one time a bottle cap exploded with so much force, it
> compressed the water
> > inside it to the fusion temperature of Hydrogen. The
> resulting nuclear
> > explosion vaporized the poor kid who built the Tesla coil, and
> he got a big,
> > fat "F" on his science project!
> >
> > A) OK, I just made that one up. But some of the
> bottle cap stories I've
> > read are nearly that silly.
> >
> > Matt, I'm guilty of making a short story long, so let me close
> with this
> > bit of advice. If you want to make salt water caps,
> stick with plain old
> > NaCl, and clear glass containers. Table salt may not be
> the last word in
> > conductive electrolytes, but it is cheap and non-toxic.
> Likewise, green and
> > brown bottles are pigmented with...what? I don't
> know! The dye could be
> > metallic salts! Do you really want unknown compounds of
> Iron or other
> > metals mixed in with the glass? Stick with water-clear
> glass and avoid the
> > whole issue. For mind-numbing text and grainy visuals on
> salt water bottle
> > caps, visit my site at:
> >
> > http://myweb.cableone.net/grcarhunter/
> >
> > Cheers,
> >
> > Gregory R. Hunter
> >
> >
> >
> > --- On Thu, 12/4/08, Matt <tonedeafmessiah@xxxxxxxxx> wrote:
> >
> > > From: Matt <tonedeafmessiah@xxxxxxxxx>
> > > Subject: Re: [TCML] TC Newbie
> > > To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> > > Date: Thursday, December 4, 2008, 11:26 AM
> > > Hello again, I'm back
> > >
> > > Just received, my transformer - I don't really feel
> > > like shelling out the
> > > money for high voltage caps (or several lower voltage ones)
> > > though. I was
> > > thinking of making a 'beer bottle' salt water cap.
> > > The transformer delivers
> > > 2x 7.5kv at 40mA. It is a danfoss oil burner transformer. I
> > > was wondering if
> > > anyone could provide me with some advice - especially as I
> > > have heard that
> > > salt water capacitors can tend to explode when things go
> > > wrong...
> > >
> > > All input and help is valued and appreciated
> > >
> > > Thanks a lot,
> > >
> > > -Matt
> >
> >
> >
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
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