Re: Liquid Layered Capacitors

["Tesla list" <tesla@xxxxxxxxxx>]

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