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Re: Not shooting for anything gloriuous, but... (fwd)



---------- Forwarded message ----------
Date: Thu, 15 Apr 1999 08:44:24 -0700
From: Bob <misiura-at-nccoast-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Not shooting for anything gloriuous, but...

Yuri,

You can use aluminum foil on the outside of your bottles for one plate
of your cap.  Try to get the foil and water level roughly even, for the
maximum capacitance, per bottle.  Choose bottles with a minimum of
imperfections in the glass/plastic (a small bubble can cause a puncture,
the same with areas of thin glass or plastic).  Plastic soda bottles
tend to puncture easily, but you don't say what voltage you will be
using. 

With plastic, you will probably need to use series caps to keep the
voltage from destroying them.  You will probably need several, series
strings, in parallel to get the capacitance you need.

The size (capacitance) you will need, is dependent on your spark
transformer's voltage and current, the size of the secondary, and the
size of the primary.

A better way to make a Leyden Jar capacitor is to use salt water on the
outside as well as the inside of the bottles.  It tends to eliminate
corona losses, and if a bottle breaks, the salt water is contained by
the outside container.  It does make a series string more difficult
(outside containers must be separated and insulated) and may exacerbate
the shock hazard . . .

Corona will create ozone and ultraviolet light, both can cause the
plastics to weaken.

Practically, a farad is a way to keep track, numerically, of the ability
of a cap to store energy (at a given voltage).  25 is a bigger number
than .002 (12,500 more charge, if the voltage remains the same for both
caps).  It is also part of the resonance formula, that will determine
the operating frequency of your coil.

Bigger primary capacitance is necessary for more turns in the secondary
of the coil (all other things remaining equal).  Bigger capacitance
means lower frequency (all other variables remaining equal).  A more
powerful transformer (measured in watts) is capable of using a higher
capacitance (voltage remaining equal).

Hope that helps
bob
Tesla List wrote:
> 
> Original Poster: "Yuri Markov" <wmondale-at-hotmail-dot-com>
> 
> Please bear in mind as you read this message that I am not attempting
> to build a solid-state coil. The primary is unmeasured and hand
> shaped. The secondary is wound on a wrapping paper tube. I am not
> looking for help abot that - I know perfectly well that it is silly.
> However, I need some help regarding the capacitor. I plan to use
> something of the salt water type. If I put water in a two liter soda
> bottle and dissolve ordinary table salt (lots of it) until it stops
> dissolving, then wrap the outside with aluminum foil, will it worr?
> Should I use several in series? In parrelell? Please help.
> 
> By the way - when a capacitor is measure in farads, what exactly does
> the number mean? I understand that it is coulumbs(forgive the
> spelling) per volt, but what does that mean, practically? What is the
> difference, say, between 0.002 uF and 25 uF? Any clarifying comment
> would help. Thanks.
> 
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