Original poster: "M G" <gt4awd@xxxxxxxxx>
Yesterday I took apart the coil in preparation for building the
portable base. I will also be making a new flat spiral primary coil,
using 50' of 1/4" copper tubing, and 1" PVC for insulated supports.
Found the tubing at Lowes for a really good price compared to the
other stores. It was only $29 dollars including tax. The 1/4" tubing
seems like it would be easier to shape than the previous 10ga. solid
copper wire used for the first primary. Should I get by fine only
using four supports with notches cut in them to hold the coil turns,
or consider using eight? I'm trying to get the new coil as even as
possible so any tips on winding it would be great.
I plan on taking apart the old primary coil and using the wire to
make a bi-polar coil setup. I might make a new secondary for the
setup using the 780' spool of 24AWG magnet wire I still have, or
possibly just design it for an easy exchange of the secondary coil I
already have onto both coil setups. It will be a while before I
start any work on the bi-polar coil though.
I was wondering what most people use for the end caps on the their
secondary coils? What I did was use two water catch plates for pots,
and cut them to size. The problem is they are made out of the one
type of poly plastic that epoxy does not bond to. Everything plastic
I can find, that would make a good end cap, is made out of this same
type of poly plastic.
When I was taking apart the coil I had just removed the nut off the
end cap bolt, and someone knocked the secondary off, unsealing what
little bond the epoxy had made. Thats the second time the secondary
has fell from a good distance, and it has held up fine. As long as
it the wire does not get cut on something sharp. What I found on the
inside has me a little worried. A good burn mark on the wall of the
PVC that was the ground side of the secondary. Here's a link to an
image.
<http://img66..us/img66/3541/1000204rc7.jpg>http://img66.imageshack.us/img66/3541/1000204rc7.jpg
Any idea why that would happen or what I should do to prevent it?
Thanks,
Matt G.
---------[ Received Mail Content ]----------
Subject : Re: A few problems..
Date : Thu, 01 Mar 2007 16:17:14 -0700
Original poster: "M G"
The max output I get right now is fine for me, but it would be nice
to get around 20" streamers. For a first coil it turned out good
enough. Just a few more things I need to do and it will be complete.
My top priority right now is to finish building a portable base that
holds all the components. If you look at the pictures of the complete
setup you can see the capacitor/TeslaMap board and terry filter board
are just sitting slightly above the ground.
The primary might be close to tuned, but due to the amount of
imperfections on my primary coil I was told finding the exact (1/4?)
resonant tap point would be difficult because a programmed
calculation, for instance using TeslaMap, would be off. For now I
have been using compaired5. It calculates the tap point to be right
before the start of turn nine. So its possible I am tapped slightly
over resonant right now, but where I am tapped seems to work best.
I checked where the secondary bottom winding sits NST to the
primary and it seems to be no more than 2" below the top primary
turn. I really cannot move the secondary up any more without finding
a new bolt that is longer, and remaking the bottom end cap. The bolt
on the end cap goes through a hole on the primary support and on its
end is placed the ground connection and a nut which holds the
secondary in place. It only has less than half an inch left that
could be moved up and the nut screwed on.
Matt G.
------------------------------------------
Original poster: "Barton B. Anderson"
Hi Matt,
Thanks for sharing the basic specs at the bottom of your post. Don't
be depressed if you don't reach the 28" spark length. Feel real good
if you get close 20" to 22"! Your coil is large enough to run a 12/60
sparklength if you feel up to it. The specs indicate your coupling is too
high (which explains your periodic racing sparks). Adjust your
secondary so the bottom turn is 1.5" below the center line of the
primary's top turn (due to your particular . This should result in a
coupling of 0.12. I would probably do that before winding a new primary.
Your max NST expected is 24" with your particular calc's (not
28"). Yes, only 4", but sparklength I use don't show 28", even on a good
day. Once you adjust the secondary, you will likely only notice that
racing sparks are not occurring and no change to spark length. This
is normal. Now, work on you spark gap. Rebuild it if necessary. This
is the obvious component for losses and is where the best increase in
kv is to be realized. Much "power" is lost in the gap.
Minimize the power lost at the gap and you will increase the power
available for output sparks. This is not always easy, but it is
definitely a very important arena to do battle in (up to 50% losses
in the gap on average). Any increase there in efficiency goes a long
way with spark lengths. Anyone who has coiled long enough realizes
the importance of a "good" spark gap. It can make or break a coil.
Take care,
Bart
---------------------------------------------
Original poster: Ed Phillips
Are you sure the primary is tuned correctly? Doesn't look like
enough turns to me but I haven't tried to run the calculations.
Ed
---------------------------------------------
>Original poster: "M G"
>
>Hi everyone,
>
>I finished my first coil a little more than a week ago. A 4" spark
>gap coil, using a 9NST 30ma kv, and eleven 2mfd .15overcoupling CD
capacitors
>in series. For past week or so I have been adjusting certain parts
>of the coil to get better output. My recent changes include making a
>tap for capacitor eleven, which helped increase secondary streamer
>output by some. Raising the secondary coil up more to prevent
>kv racing arc's. Still seems to happen on full power runs.
>
>The secondary appears have not received any damage from the
>problems, but I will probably add more polyurethane coats just in
>case. Some may remember that my primary is at too high an angle, 55
>degree's. Is it time to just scrap the primary and make a flat
>spiral or can I get good coupling just by raising the secondary up
>more? So far the best output of the coil is only around 12-14",
>which is no where near the 28" that should be possible using a 9PSU
>30ma NST. The coil uses a "Terry filter" setup as shown in the
>standard filter schematics. I was wondering if the filter degrades
>overall performance some in trade for less stress on the topload?
>
>The toroidal topload, 4"x8.5", is made from aluminum ducting, and
>covered in aluminum tape in an attempt to smooth out the sharp
>points some. Secondary end is connected to appriciate by end of the
>wire. I have yet to make the secondary top end cap. Secondary bottom
>ground, with end cap, is made with end wire wrapped around solid
>brass bolt. I would stramers ANY suggestions for improving the
>coil output. Max output is around 10" with occasional 12-14" air imageshack.
>
>All of the images I have taken so far of the coil can be viewed on
>my imageshack public page.
>Link: http://profile.imageshack.us/user/gt4awd/
>I would just put links if there was not so many images.
>
>Here are some coil specs I did not mention.
>
>Secondary: 4.20"x20.25" using 26AWG single build magnet wire on
thin wall pvc.
>
>Primary: 55 degree angle using 10AWG non-insulated solid copper
>wire. Tapped at turn 9.7 with a total of 11 turns. Inside diameter
>is nearly 7", outside diameter 13", height of 4.5", and primary turn
>spacing of about 1/2". Both connections leading to primary are
nearly 2' long.
>
>Wire: Primary circuit wire and ground wire using 12AWG insulated
>solid copper wire.
>
>Filtering: Standard "Terry Filter" for high voltage end, and a 2x10
>amp CD RFI filter for mains line.
>
>Ground length: Coil support stands about 2' above ground level.
>Ground wire has a total length of around 15'.
>
>I might be missing some important information. Let me know if I am.
>
>Thanks,
>Matt G.
----------
Create and Share your own Video Clip Playlist in minutes at Lycos
MIX (<http://mix.lycos.com/?if_Event=MAILmixtagline>http://mix.lycos.com)