Re: Coil Form needed

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

Original poster: DRIEBEN-at-midsouth.rr-dot-com 



----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
Date: Wednesday, May 12, 2004 9:20 am
Subject: Coil Form needed

 > Original poster: "Paul Marshall" <klugmann-at-hotmail-dot-com>
 >
 > I am looking for a coil form 12" or greater diameter. The length
 > should be
 > about 4 times the diameter. Also I am planning on using a 40kV
 > .5uF
 > capacitor for the tank circuit. I have a 25kVA pig to drive it.
 > Has anyone
 > on the list ever used that much capacitance in their tank circuit ?
 >
 >
 >
 > Paul S. Marshall

Paul,

I would think that 0.5 uFD would be way too large for
anything except maybe for an Electrum sized coil. The
biggest cap that I've used so far is .0825 uFD, but I
do now have (2) 0.1 uFD, 50 kV Hipotronics custom Tes-
la caps that I got from Jeff Parrise of KVA Effects.
I plan on using one of these for my future BIG coil
project and driving it with a 15 kVA pig.

As for large diametered secondary coil forms, I was
able to get gray PVC ducting pipe from a local plas-
tics supplier. I had picked 12" but they had 18" too.
Of course it was quite pricey, though. I payed over $5
a foot for the 12" and I'd hate to even ask how much
the 18" was ;^0 Another cheaper alternative is the
concrete former tubes. They are cardboard and are
considered to not be the best form material due to
higher lossiness and low Q, but if thuroughly dried
and varnished, they do work. I know from experience.
My biggest coil to date used a 12" dia cardboard
"Quiktube" concrete fromer from Home Depot and it
was only about 38.5" long but gave 8 to 10 ft. sparks
from a 9x30 toroid and driven by a 10 kVA pig (14.4 kV)
and with the aforementioned .0825 uFD primary capa-
citance and a homemade lexan and brass RSG.
I've seen 24" concrete formers at construction sites
so you could definitely build a large coil with one
of these.

David Rieben