Re: Salt Water Caps

You wrote: 
>I have completely finished my coil except for the capacitor.  I'm 
>planning to build some rolled polyethylene caps as soon as I gather the 
>required materials and find the time.  Until then, I would like to easily 
>construct a salt-water capacitor so I can play with the coil until I 
>build a better unit.  I was not really able to find anything online about 
>salt-water caps, but I keep seeing references to them.  What would be 
>required to build one capable of withstanding a 15 kv, 60 ma neon 
>system?  The secondary is 24 inches, 6 inches diameter, 880 turns 22 awg 
>magnet wire.  Primary is 14 turns, conical spiral, 1/4 inch copper 
>tubing.  Spark gap is a 6 inch, 16 electrode disk rotary system.  Any 
>advice would be greatly appreciated!

Sit back and I will tell the tale of my first salt water capacitor.  It 
consisted of 7x7 rows (that's 49) one liter glass 7-UP bottles.  They were 
placed in a wooden tub that had a galvanized steel liner.  A solution of 
super-saturated brine was poured into each bottle up to about 4" from the 
top.  The tub was filled to the same level.  It is now obvious that the water 
in the tub is one capacitor plate and the water inside each bottle is the 
other.  The bottle, of course, is the dielectric.  A 1/2" dia copper tubing T 
fitting above each bottle was fitted with a piece of pipe going down into 
each bottle to contact the solution, and horizontal pipes to connect to each 
other.  This capacitor stood up to 14,400VAC at about 6KVA.  Each bottle was 
good for about 900pF.

This capacitor worked well and was next to free to make.  However, the 
difference in spark when we went to real store-bought capacitors was more 
than subtle.  The sparks went from OK but kinda wimpy to mean snapping white 
discharges.  You will get the same result with your homebrew polypropylenes.
Good luck.

Incidentally, Tesla used bottles in Colorado Springs from the Manitou Water 
company in nearby Manitou Springs.  When I was there a few years ago, I 
combed the many antique shops for a Manitou Water bottle from that era.  The 
dimensions and a sketch of the bottle are given in Tesla's Colorado Springs 
Notes so I knew what I was looking for among the zillions of old bottles in 
the antique shops.  The shop employees and patrons thought my girlfriend and 
I were crazy measuring old glass bottles going "Nope, not the one.  Next."  I 
quickly learned not to even try to explain what I was doing and why the 
bottle had any particular significance.  I finally found one that was real 
close and bought it.