RE: Liquid Layered Capacitors

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx>

As far as the opposite charge problem, I did leave out one component 
of my idea ... to drive nails into the bottle and seal them on 
alternating layers, then connect all the nails on each side 
together.  The other problems are certaintly real though.
More what I was wondering was if the general concept of layering 
liquids that can then harden on top of each other had any inherent 
problems.  Different materials could be used other than salt water 
and oil, such as molten metal and paraffin or some other kind of 
plastic that could be melted.  How would the following variation, 
made of different materials, work?
A 2-liter plastic soda bottle has nails driven into it with one 
column of nails on each side.  The nails on each side are equidistant 
from each other, and the nails on one side would be offset from the 
nails on the other side by half of the nail-to-nail distance, forming 
contacts for different layers inside.  The spacing of the nails could 
be determined mathematically taking into account the dielectric 
constant and breakdown voltage of paraffin.  Then liquid paraffin is 
poured into the bottle until it comes up to just under the first 
nail.  This is allowed to harden, and a layer of molten metal (some 
alloy that melts at a relatively low temperature so as not to melt 
the paraffin or bottle before hardening) is poured in so that it just 
covers the nail.  After hardening, another layer of paraffin is 
poured in until it reaches the next nail (on the other side), and so 
on.  After the bottle is filled, the nails on each side would be 
connected together to form the leads of the capacitor.
It seems to me that this would solve most of the problems that you 
mentioned, except perhaps the dielectric issues, and paraffin could 
potentially be substituted for some kind of plastic that could melt 
at reasonable temperatures but would have better dielectric properties.
I have a source of molten metal at work (some kind of alloy that does 
melt at relatively low temperatures), so if nobody sees any problems 
with this new design, I'll probably try it out.  If paraffin is a bad 
dielectric, could someone recommend a better dielectric that is hard 
at room temperature but can be melted relatively easily?

Thanks,
Chris




-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Sun 11/26/2006 9:34 PM
To: tesla@xxxxxxxxxx
Subject: Re: Liquid Layered Capacitors

Original poster: BunnyKiller <bunnikillr@xxxxxxx>

There are several problems with the design...

each "layer" of salt water would have to be of an opposite charge.. 1
layer +, the next - , then + again...etc. getting a conductor thru
each layer without shorting it out would be difficult.

if it could be done, the heating of the cap while running would "melt"
layers and mixing would occur, or most likely, separate and become
just one layer of saltwater and one of oil.

the dielectric constant of oils isnt that high to start with so you
would need a rather thick layer to hold off the voltages used in coiling.

which brings us to another problem, the thicker the insulating
material, the less effective the cap becomes thus leading to a rather
big cap to produce the voltage rating and the amount of farads needed.

the best bet is to take the time needed and save the money for a MMC
( multi-mini cap) capacitor.  If you go the route of trying to make
your own cap, you will spend 2 - 3 X the money trying to make one
that works...  you will blow up the first 2 or 3 home mades and thats
a fact!!  Buy commercially made caps, save yourself the cost,
frustration, and time of homemade caps...

Scot D




Tesla list wrote:

>Original poster: "Breneman, Chris" <brenemanc@xxxxxxxxxxxxxx>
>
>Hello,
>
>I'm new to building tesla coils, and am trying to get my first one
>built.  The problem is that I have very little money available to
>spend on materials.  The main thing I'm trying to get now is a
>capacitor for the primary circuit, and it looks like my best option
>is to build one.  I've seen a number of designs for homemade
>capacitors, but came up with one myself, and was wondering if anyone
>has tried it, or if there is any inherent problem in the design.
>I was thinking that the most efficient and easy-to-build designs
>were liquid capacitors where at least one of the plates is a liquid
>such as salt water.  The most common design of a liquid capacitor
>seems to be filling bottles with the solution and putting them all
>in a vat with another conductive solution.  But isn't this wasting
>space due to the large plates?  The best space-savers seem to be
>layered capacitors, which also seem to be pretty efficient (from
>what I've read), but the recurring problem is apparently that the
>solids don't get extremely close contact with each other.  So I got
>thinking ... what if a layered liquid capacitor could be built?  Or
>more like liquids that could dry.
>Here's one specific design idea that I had: Inside of some kind of
>bottle, put a small amount of salt water, then a layer of olive oil
>as a dielectric.  Olive oil will float on top of the water and
>generally has a higher freezing point than water
>(http://www.oliveoilsource.com/olive_chemistry_freezing.htm) so it
>should be possible to freeze this or at least make it harden
>somewhat without causing the water to freeze and expand - this could
>potentially be done in a refrigerator.  After the layer of oil
>hardened, a small layer of hot glue could be placed on top of it to
>prevent it from mixing with above layers.  Then more salt water
>could be added, and the process repeated, until there were enough
>layers to fill the bottle.
>One problem with this is that I can't find the breakdown voltage of
>olive oil.  Does anyone happen to know this?  Also, is there any
>mechanical or other problem with this design that would prevent it
>from working?
>
>Thanks,
>Crispy
>
>