Re: More Fun with Bottle Capacitors

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: More Fun with Bottle Capacitors
From: Tesla List <tesla-at-stic-dot-net>
Date: Thu, 13 Nov 1997 21:37:26 -0600
Approved: tesla-at-stic-dot-net

From:	Esondrmn-at-aol-dot-com [SMTP:Esondrmn-at-aol-dot-com]
Sent:	Thursday, November 13, 1997 1:39 PM
To:	tesla-at-pupman-dot-com
Subject:	Re: More Fun with Bottle Capacitors

In a message dated 97-11-13 14:24:33 EST, you write:

<< Did some more tests with 750ml wine bottle saltwater & foil caps. 
 Today I used a Fluke tabletop digital multimeter to do the current
 measurements instead of the Fluke 87 pocket model.
 
 With four bottle caps (two in series with two) I got a really
 peculiar result.  When I applied power to my 15kv/30ma neon xfmr, I
 heard a loud snapping sound.  To my amazement, I saw (& heard!) a
 spark periodically jumping AROUND the standoff insulator to the case
 of the neon!  An incredible jump for 15kvac.  I'm using the outdoor
 model "Transco" xfmr with ribbed, ceramic HV terminals on each end. 
 The jump distance around the insulator to the case is probably a
 couple of inches.  I'd love to know how it was doing that.  I got in
 such a hurry to kill the power I forgot to measure the series
 current.
 
 In the next test, I ran six bottle caps--three in series with three.
 The anomalous spark did not reappear.  The Fluke meter said the
 series current thru the caps was 32ma--max current for my neon.
 Obviously, the bottle caps have even more capacitance than I
 estimated earlier.  
 
 I ran the six caps for several minutes at 15kvac.  They didn't fail.
 I'm going to go with this "sixpack" configuration for my little 4.5"
 x 23" coil and see how it does.  I wish I had a real capacitance
 meter.  Maybe I'll build or buy one before I start my next coil
 project.  15kv is more trouble than it's worth.  My next neon will be
 9 or 10kv -at- 60ma.  I'll get more power with less voltage--much easier
 on the caps!  I've also got a matched pair of 900w microwave xfmrs. 
 These would make a robust low voltage/high current supply.  I've 
 already started thinking about my 6" coil...
 
 Greg
  >>
Greg,

Good experiments again.  Be careful in doing this.  It will destroy your
transformer.  One of the earlier instruction sets for building rolled poly
caps said to connected it directly across a neon sign transformer and let it
cook for a few hours to help get the air bubbles out.  I did this and the
transformer got very hot and died.  I think it developes a 60 hz resonant
condition and overvoltages the neon secondary.  It must be the case because a
dead short across the transformer should not hurt it.

Ed Sonderman