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Re: [TCML] Capacitor calculator?
Beer bottles with salt water for the inside plates and foil for the outside plates work well. Beer bottles are a good choice because they are free from the trashcan, and because they are made of very thin, strong, glass. A single 12oz beer bottle will yield 750-900pF. A six-pack in parallel is good for about 5nF. I've verified my approximate values using the cap function on both cheap and expensive digital multimeters.
I'm not as certain about the voltage rating, but my 11kv pole transformer never cracked a bottle, even running an asynchronous RSG, so 20kv peak is probably a conservative rating.
Some coilers have reported overheating, cracking, and catastrophic failures with saltwater caps, but I was never able to duplicate these results. Mine held up fine. However, they are way too heavy and bulky. The only good thing about them is the low cost. For rather dated documentation of my experiences with saltwater caps, see:
http://myweb.cableone.net/grcarhunter/bottom.htm
http://myweb.cableone.net/grcarhunter/swc.htm
http://myweb.cableone.net/grcarhunter/bottle.htm
My fixation with bottle caps was not and is not main-stream (if there's any such thing in coiling!) I was a bit of a bottle cap extremist. I'm over it now. Plastic film caps rule!
Happy Sparking,
Greg
--- On Wed, 9/16/09, Brian Hall <brianh4242@xxxxxxxxxxx> wrote:
> From: Brian Hall <brianh4242@xxxxxxxxxxx>
> Subject: [TCML] Capacitor calculator?
> To: tesla@xxxxxxxxxx
> Date: Wednesday, September 16, 2009, 11:12 AM
>
>
> Does anyone know of a link to a good site (or what the
> formulas are) for calculating the capacitance AND max
> voltage of a leyden jar/saltwater cap/stack of alternating
> styrofoam cups and tin foil type
> cap? Container dimensions, sueface area of
> conductor if it matters, etc.
>
>
>
> And for the saltwater leyden jar, how does one figure out
> the teaspoons of salt to ounces/some standard measurement of
> water ratio in terms of how it affects the capacitance and
> max voltage? I have made a small TC with snapple
> bottle saltwater caps in series, and got lucky with random
> guessing to get nice bright 1" sparks ... but I have a
> bigger coil under construction now. I know they can be
> lossy and messy if spilled but I know they work.
>
> ----------------------------------
> Brian Hall
>
>
>
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