Re: A Little more than general questions

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

Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bigfoo39-at-telocity-dot-com>

Tesla list wrote:

> Original poster: "Wade B AndB Anderson by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <nabedaw-at-juno-dot-com>
>
> Hi folks,
>   I am going to turn my questions to the primary and secondary windings.
>
> By increasing the diameter of the secondary coil, I will increase wire
> resistance, that is a gimme. In what ways does that affect the coil
> operation???
>
> Why is 1,000 turns of wire the magic # for this coil??? Of course if the
> turns are increased or decreased the inductance is affected, as would be
> the inductive reactance, as is it's ability to establish a magnetic
> field.
> And of course the secondary voltage is directly related to the # of turns
> in relation to the primary.
>
> My question is, what effects ( to the operation of the coil) would result
> if the turns are say.... doubled, or halved???
>
> On the primary coil how many turns would you all recommend??? Maybe a
> ratio to the secondary???
> And at what spacing???
>
> >From what I can gather from previous responses, it sounds like that a
> flat or coned primary is just a matter of preference??? Is there a
> different affect if the primary windings actually surround the secondary,
> other than the fact that one may risk damaging the primary with secondary
> strikes.
>
> Thanks, all of your comments are very helpful;
>
> Wade

Hi Wade...

by increasing the secondary size ( dia.) doesnt really increase the
resistance ( if you use the same
length of wire) but it will increase the Cself of the Sec. ( a minimal amount)

as far as 1000 turns .. that just happens to be the number the general
conciensus has agreed upon to put
on the secondary..   there are coils with 600 turns and some with 1600
turns  both work quite well.

the primary normally consist of about 12 turns on the average. ( due to
capacitor limiting factors and
space) I base my primary turns off of the capacitors i can get. Most
primaries are coiled with about .25"
space between the windings,  for 2 reasons,  1. the ability to place a
clip, clamp, or what ever
connecting device to the tubing ( which is usually 1/4" copper tubing for
lower powered coils) and reason
#2. the voltage gradient between turns for an average med - to low powered
coil runs about 1000V, thus
.25" is sufficient to hold off arcing from wind to wind. There is another
reason which Im not too familiar
with and that is the amount of primary turns has something to deal with
inductance surge (???)

as far as ratios go there has been some speculation that the secondary
diameter to the secondary height
should be 1 : 3.14  ( Pi)  a bit on the short side for my preferences. I
prefer a 1:5 ration on
width/height.

on average the ratio of primary turns to secondary turns "seem" to be 1:100
but since we are dealing with
Reso rise factors and not direct transformation this theory of
"transformation" doesnt really apply.

flat primaries compared to coned or even helical primaries are the results
of the "K" factor, the coupling
of the magnetic field that is imposed upon the secondary. The higher the
coupling to the secondary ( the
more the primary is enveloping the secondary base) , more energy is
transfered to the to the secondary
from the primary. Sounds great ... but there are some difficulties when the
coupling is increased.  first
off, the likelyhood of secondary spark racing increases ( which is bad) the
quenching of the spark gap
becomes difficult ( I'm still trying to understand that one) and a few
other nasty items which I  have
heard about but dont remember.

hope this tidbit of info helped    and if there is anyone out there who
knows why the gap quenching
becomes more difficult with increased coupling I'd like to know why :)


Scot D