Re: Coil Doesn't Fire

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

Original poster: JBarrett-at-trumbullcorp-dot-com 


Man you guys are a wealth of good information! Thanks!
When I power up my coil the spark gap immediately begins to fire. It is 
pretty loud too. I had it set to 1/4" and tried to open it up slightly 
until it wouldn't fire at all, or the air psi applied would quickly quench 
the spark. My gap consists of two solid brass dowels mounted in 1 inch 
thick plastic shaped in the form of an U. A set screw in the plastic allows 
for adjustment of the two dowels and air is applied through the bottom.

The only way I can get any fire at all from the torrid is if I suspend a 
ground wire to within two inches of the torrid. Even then the corona is 
very very small.

As far as the caps go I must admit ignorance on this. I purchased these 
caps from Ebay because I thought they were similar to the ones Terry Fritz 
uses. The funny thing about these caps is nobody seems to know anything 
about them. Each cap has a 10 meg bleeder resistor .      Ebay Description 
Below
Description
 > > >SEALED BAG OF 100 PANASONIC HIGH FREQUENCY
 > > METALLIZED
 > > >POLYPROPYLENE FILM CAPACITORS. PER PANASONIC'S DATA
 > > >SHEET "DESIGNED FOR APPLICATIONS WHERE HIGH
 > > FREQUENCY
 > > >AND HIGH PULSE ARE REQUIRED". .0043 MICROFARAD,
 > > >2500VDC, PANASONIC PART # ECW-H15H432F7

.  Maybe this will shed more light on the situation.

Thanks Again for everyone's input.
Jim Barrett


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

09/16/2004 07:36 PM
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Subject
Re: Coil Doesn't Fire




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