Re: first, second and third light of a flat coil

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

Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

I have a question about your primary orentation. You said output in the
center like Tesla. I would have started witn my spacing near the low voltage
edge and farr at the high voltage center.THIS WOULD REDUCE the coupeling
where the problems are the greatest.
   Robert  H

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Mon, 04 Mar 2002 20:51:07 -0700
> To: tesla-at-pupman-dot-com
> Subject: Re: first, second and third light of a flat coil
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Mon, 4 Mar 2002 21:12:30 -0700
> 
> Original poster: "marc metlicka by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <mystuffs-at-orwell-dot-net>
> 
> Paul, Bart, All
> 
> Tesla list wrote:
>> 
>> Original poster: "Paul Nicholson by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>
>> 
>> Hi Marc,
>> 
>>> I wound a somewhat conical primary that hangs under the secondary,
>>> 70 deg. angled inward, 11 turns at 20" in.
>> 
>> Can you give us more details of the primary, and its position
>> wrt the flat secondary?
> 
> I glued popsicle sticks extending from the underside of my paneling
> coilform, These are set at a 70 degree angle inward toward the center.
> The primary windings are of 18g mag wire with the first turn starting 1"
> from the base and a spacing of 1\2" between turns, 11 turns total.
> My thinking in using the inward angle was that it seemed to look like it
> would give me the best interaction of the flux field lines cutting
> across the secondary? For tapping i just scrape the enamel off were i
> want to place a tap.
> 
> 
>> 
>>> Racing arcs along the sec. windings are a real problem.
>> 
>> At what firing voltage does the trouble start?
> 
> I'm using a 12\30 nst and tsg, a 22nf cap gives what looks tuned the
> best at 7 turns. This could be a little wrong because i just couldn't
> keep the racing arcs down. The racing arcs extend in a radial pattern
> from the inner turns outward to the outermost turn like spokes in a
> wheel. There are many of them at once, they are very strong blue\white.
> I tried extending the center bolt to three inches and placing a 6" spun
> toroid on it to shield the inner turns hoping i could get topload
> breakout instead of racing arcs. It seemed to help some with a fuzzy
> corona like discharge from the toroid as the tap\tune started to come
> in, then the spoke arcs would start again. I also tried one of those
> expanded aluminum down spout screen units for a topload, These look like
> a 150w light bulb that is made of expanded metal, i was starting to get
> 1"-2" leaders from this along with the radial spoke arcing, this is when
> i noticed the massive amount of carbon pinholes in the center windings.
> 
> What are your
>> primary cap and tap settings?  You'll need to retune by 20% or 30%
>> between the rim-grounded and center-grounded configurations.  Do
>> the racing arcs form at a particular radius on the coil?
> 
> The spoke arcing would very within the inner turns of a 2" diameter
> circle, not always coming from center bolt out but sometimes from 1\2"
> to 1" away. 
> Bad news now because the inner 1" or so turns have been burnt so bad
> that i had to remove them, I will have to rering the operating
> parameters for this coil before we can do more modeling on it, sorry
> Paul.
> 
> It was somewhat my fault for not setting up a ground rod to allow the
> discharge an easy path or contact surface, i should have done this
> rather then trying free air discharges right from first light (hind
> sight 20\20). It was very exciting experimenting and am looking forward
> to more.
> 
> I have since removed the inner turns and i put a layer of pvc tape
> across the coil to try to give some insulation to the 28g mag wire in
> the windings to try to curb some of the arcing. I will also use a variac
> to bring tank voltage up slowly from 9kv up to the 12kv.
> 
> 
>> 
>> It would be nice to model this situation.
> 
> I am hoping that i can remove the primary easily so i can ring out the
> new L-R and fres due to new 8 7\8" winding area extending in from the
> original 20" diameter, If not no biggy, the primary was only hoaky'd
> together for a start.
> I should have a few pics on my site by the time this is posted:
> http://www.fortunecity-dot-com/meltingpot/syria/1210/index.htm
> Follow site map to "flat coil" page.
> 
> More to come soon,
> Marc M.
> Geek #1055
> (PI geek)
> 
> 
>> --
>> Paul Nicholson
>> --
> 
> 
>