RE: Quick and dirty capacitors

Here's an old post of mine that may help.  While salt water/glass caps are
not great, I suspect wax paper would be even worse.  The slightest warming
up and your dielectric is gone.  Enjoy!

As a point of reference, I built a quick salt water cap out of a 16 oz
Nestea glass bottle.  The bottle measured 6.9" H x 2.8" Dia.  I filled it
with salt water (I didn't bother with the oil layer since I was only
interested in the cap value, and the oil has no effect on that).  I
wrapped the exterior with aluminum foil to a height of 4.5", just where
the sides go from straight to curved.  I stuck a piece of stranded wire
into the water.  The length of immersed wire had no effect on the
capacitance, but it would affect the amount of losses in an actual Tesla
coil application.

I measured the value on my Wavetek 27XT multimeter, which is able to read
capacitance.  After subtracting the lead capacitance, the net result was
a capacitance of 0.57nF, or 0.00057uF, or 570pF, per bottle.

Still no idea to what voltage one bottle is good for though.

Gary Lau
Waltham, MA USA

>Original Poster: "Yuri Markov" <wmondale-at-hotmail-dot-com> 
>I am looking for a way to construct a capacitor who's capacitance I would 
>have SOME rough idea about. I've been shooting in the dark too long with 
>vast arrays of glass bottles. Could somebody tell me a somewhat quick and 
>inexpensive way to make a capatitor out of, say, aluminum foil and wax 
>paper? Or, if somebody knows the exact capacitance of a specific type/brand

>of bottle, could they please tell me? I realize I can measure the bottle 
>myself - yeah, with an accuarcy of +/- 50%. Not good enough. So if anyone 
>knows roughly the exact capacitance of a certain brand of bottle, PLEASE 
>tell be. I'd appreciate it a WHOLE lot. Thanks.
>-Yuri Markov