Re: Coil Doesn't Fire

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

Original poster: "Harold Weiss" <hweiss-at-new.rr-dot-com> 

Hi,

On your gap, watch that it does not get too warm or it will melt the
plastic.  It sounds like you are out of tune.  Start on the outer turn and
work in one turn at a time, and see which turn gives the best spark.  Then
work back and forth on that turn for fine tunning.  If then you are still at
2" then you will have to add to or subtract from your capacitance and try
again.  Your capacitors are on the small side for MMC building, but they are
the good Panasonic ones and are perfect sized for Terry filters.  The .1-.15
uF ones would be best for MMC building.

David E Weiss

 > 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 fir   e.Itis
 > 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
 > To
 > tesla-at-pupman-dot-com
 > cc
 > 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
 >
 >
 >
 >
 >