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From: keithd@cadovax.UUCP (Keith Doyle)
Newsgroups: net.analog
Subject: Re: Jacob's Ladder
Message-ID: <646@cadovax.UUCP>
Date: Mon, 3-Jun-85 14:33:21 EDT
Article-I.D.: cadovax.646
Posted: Mon Jun  3 14:33:21 1985
Date-Received: Sun, 9-Jun-85 23:58:22 EDT
References: <72@biomed.UUCP>, <344@moncol.UUCP>
Organization: Contel Cado, Torrance, CA
Lines: 57

[.............]

No, an expensive neon sign power supply is not required, an inexpensive
neon sign transformer is (unless you think $10.00-$30.00 expensive).  
I would suggest you look in the phone book under 'signs' for someone who
does neon sign repair.  You can usually obtain a used 15kv transformer
relatively cheap from such an outfit.  I have a 15kv 60ma transformer I
use for a Tesla coil.  I only paid a couple of bucks for it (this was in
1971).  15kv 30ma transformers are common, and for a jacobs ladder you probably
can't tell the difference.  And basically, that's it.  115v in, and 15kv out.
All you have to do is come up with a couple of metal rods and some sort of
insulative base, (I've used plexiglas).  You want to position
the rods such that at the bottom, they are about 1/4 to 1/2 inch from 
each other, and at the top, about 2-1/2 to 3 inches.  Some time ago, I made 
one using a curtain rod (the cheap kind with the 2 pieces that slide in and 
out of each other).  I took each piece, and flattened about 1-1/2 inches on one
end of each one, drilled mounting holes in the flattened end, and bent
the end and used this angled flange to mount it to my insulative base.
With this setup, I could get the arc to rise 2 to 2-1/2 feet.  The closer
the rods are to being perfectly parallel, the farther the arc will climb,
but if they are completely paralell, the arc will probably stay at the 
bottom.  If you have trouble making it climb, try making the distance between
the rods at the bottom a little larger, and/or spreading the rods at the top
a little more.

       *        *
       *        *
       *        *
       	*      *
       	*      *
       	*      *
       	 *    *
     __  *    *  __
    ******    ******
     []          []
     []          []
[][][][][][][][][][][][][]

key:   * = metal rods
       [] = insulative base
       -- = screw heads (for mounting rods to base)

Attach the two output terminals of the transformer to the two rods, and 
away you go.

Again, the usual warnings:  15kv is DEADLY!  And, many times the
center tap of these transformers is connected to the metal case.  If you
mess with this with the transformer sitting on the concrete floor of your
garage or something, you will have 7.5kv between either insulated output
of the transformer and ground.  I used a jacobs ladder like this for a
Halloween's haunted house once, and encased the whole thing in clear plexiglass
so that no one could get near it.  ( with slight ventilation at the top)
Use in well ventilated area, as OZONE is a major by-product.

Keith Doyle
#  {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd