RE: My coil/Commercial caps

Hi Stan,

You wrote:

>I'm writing to ask for some assistance. The stats on my coil are:
>Secondary:      6.25" X 26.25", #20 AWG magnet wire
>Primary:        30 degree inclined, 12 turns,11 inch inner diameter
>Spark Gap:      Cylinder Static gaps, about six nominally
>Power Supply:   Down to 2 15-30 neon sign xfrmers until I fix a few more.
>Capacitors:     5 18 quart Rubbermaid(tm) buckets.
>Total C:        20 nF=.02 uF
>Problem:        My best spark length is a crummy 15". I have tried
>several things to increase it, including an 8" inner turn 30 degree
>primary, removing approx. 2 inches secondary winding, and various
>discharge terminals.  My assumption is that the buckets cannot hold
>enough energy to make a larger spark.  I am going to try replacing one of
>them with capacitors made from either Mason jars, or my original plan,
>tea bottles, this evening.
>Question:       Does my assumption about the energy capacity
>of the buckets sound correct?  Please, guys, don't tell me to just build
>rolled caps, the cost of the PVC alone here makes it more desirable to
>buy commercial caps.  Suggestions, comments, accusations of stupidity for
>something I  may have overlooked are welcome.

Power, Power, Power!  It sound like your spark is good for 900 watts.  Sure some
commercial caps will increase Q.  There are plenty of little tweaks you can
make.  You have already tried several, including the increased coupling.  But
when it comes down to it, you need more power.  You MIGHT be able to get up to
20" with increased efficiency, but I wouldn't hold my breath.  If I had to quote
a rule of thumb for spark length VS power, I would say that for every 1 KVA, you
can get roughly 1.5' of spark.  Since you have (2) 15000 VAC, .03 A
transformers, you have 900 watts, or .9 KVA.  You should be able to get a few
more inches, but probably not much.

I'm almost at the point of trying to buy those commercial pulse discharge caps.
As I have said before, I am trying to get people together so we can make a group
purchase to get a good price.  See my post I am making on this today.  I have
some prices and specs.

Scott Myers