Re: Coil Doesn't Fire

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Esondrmn-at-aol-dot-com 

In a message dated 9/15/04 11:52:36 AM Pacific Daylight Time, 
tesla-at-pupman-dot-com writes:


>Original poster: JBarrett-at-trumbullcorp-dot-com
>
>
>Hey I bet no one has had this problem. Just kidding!
>
>Transformer:
>12,000 Volt 30 ma
>
>Caps
>Panasonic ECW-H 0.0043uf +- 3% W.V. 1500 VP-P 2500 VDC with a 1 megaohm
>bleeder resistor across each cap. 8 in series 12 parallel.
>
>Secondary
>21" of 22 guage wire on a 4 1/2 inch PVC Pipe
>
>Primary
>14 turns of 3/8 copper tubing mounted on 3/4 inch plastic risers set at 30
>degrees. The inner radius is 5 1/2inches.
>
>Torid
>22 inch major radius of 4 inch flexible dryer duct mounted on aluminum foil
>covered 1/4 inch plywood.
>
>Spark Gap
>Air cooled at 25 psi
>
>Grounding
>2- 4 foot ground rods driven into ground and soaked with h2o.
>
>I believe my caps are the major source of the prolem however someone
>pointed out that my transformer is a little small too.
>Any other thoughts?
>
>JIM


Jim,

What is the coil doing?  Is the primary spark gap firing?  With a low power 
coil like this, you don't need a blown gap.  A static gap made of 1.0" 
copper tube sections about 3.0" long would work fine.  Use about six copper 
tubes with about .020" to .030" gap between each.  Then start by using only 
about four of these gaps to see if you can get the coil running.  It is a 
good idea to use a small fan for cooling on the gap.

If the gap doesn't fire, either something is wrong with the transformer,or 
the caps or it is not hooked up correctly.  I am not familiar with the caps 
that you are using.  Are these the good poly/metal foil caps?  The total 
equivalent capacitance is only .0065 ufd.  That is kind of small for a coil 
of this size.  Some quick calculations show the coil should tune as is with 
the primary tap set at about turn 12.5.

I see Gary mentioned the bleeder resistors.  That is a good catch.

Ed Sonderman