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Coil design questions.
I have built one coil from a book and got pitiful performance. After
reading here and on varrious websites I think I have enough info to start
again. I did just about everything wrong the first time so any info here
that can save me time/money would be appreacted.
The plan.
6" dia 24" long PVC Secondary wound with 22 AWG for 888 turns. PVC sanded,
dried, and treated.
Inverse conical primary from 1/4" copper tube starting at 8" with .200
spacing and 30 degree slant.
Rolled poly cap(s) WinTesla says .0108 mfd should do it.
I was planning on using the design from the list archive page.
15kv 30ma Neon
RQ Style static series gap
6A Varriac
Topload of about 14 pf.
-----
Now, this seems to fit, I was planning on using one rolled poly cap of the
design listed which with 90 mil poly should give me .0100 mfd according to
the docs, I was thinking to build two of them right off just in case. The
doc states that it will handle a coil with input of 15KV.
For the poly, I think 90 mil is the way I should go. Are 3 30 mil layers
prefferable to a 60 and a 30 or otherwise?
For the oil soaking does layering oil soaked paper in with the poly sheets
help? If I do so that will affect the thickness of the dielectric. Is
replacing a poly sheet to compensate a good idea? I'm leaning against
this and would preffer to just parallel 2 of them if I do add the
paper. "better safe then sorry".
I don't have a vacuum pump and would preffer not to buy one. I can let
them sit for a while before use and plan to break them in with the NST and
varriac. I would preffer not to have them explode. :)
If the vacuum is that important any idea on where I can obtain a cheep
pump?
Any ideas where the primary will tune? I found a good price on a 50ft roll
of copper tube and don't mind using the whole thing if I need it. The
calcs I have from WinTesla and the spreadsheet on the archive page think I
can get 12-14 turns starting from 8 in.
For the topload, I was thinking of using the duct wrapped in foil method.
But the copper spheres mentioned on the list today calc to a higher
capacitance for a 6" then the torriod that I was planning. And it would
look cooler and be eaiser to work with. Is there a prefference on sphere
vs. torriod for this?
The transformer/cap match equations seem to think I want 60ma for this
size cap. Can I get by with 30 or should I go up to 60? I don't mind
limited performance for the first runs and I allready have the 30 ma
transformer from my previous efforts. Any estimates on performance either
way? Would putting another 30 in parallel overload my varriac? Do I need
PFC on this thing? :)
For hookup wire I would like to use the 8 AWG power cable I use in my car.
It's very flexable and is made from thousands of tiny strands. I am
concerned about the insulation. Has anyone used simmiliar cable for the
connections on a coil? I would like to use it in the caps too, so
breakdown is important. Is encasing it in poly tubing a workable way to
prevent problems? I believe it's made by "Monster Cable".
For oil filling the caps I found a local jobber I can get Shell Diala AX
from for what seems to be a reasonable price ($25/5 gal). Is there any
problem using this oil in a cap? I've read on the list that it is a good
oil, I just didn't see anything saying what for. They tell me it's a
transformer oil, which seems to fit the requirement. Any idea how much oil
I need for 2 caps?
For the neon protection network I need caps, where can I get some? :) What
exactly do I need for this? I found a doc thinking that the LC filter was
prefferable to RC. I don't really know and don't want to start a debate.
Any pointers? I need to keep the cost reasonable so please keep that in
mind. :)
Thanks if you got this far, I'm a bit new and thought I should ask all the
questions I could think up in one message rather then flood the list with
posts over the next week. :)
Any thoughts on my proposed system would be welcome, even to say I'm an
absolute idiot. :) If you do that please provide somewhere to look for
more info though! :)
Saftey tips are great too, after shocking myself on the primary of my last
coil I'm pretty carefull now though. ;) I think I'll build a box for the
primary circuit this time.
Thanks!!
Travis