Re: Practical limit to number of turns on primary ? ? ?

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 1/27/03 1:34:26 AM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

Steve, all,

I've found the best efficiency when using a rather large number
of primary turns on a small coil.  For example my old research
coil used about 18 to 22 turns, and gave 42" sparks from a normal
12/30 NST.  By using a lot of primary turns, the surge impedance
is raised, and the gap losses are reduced as a result.  Also, coils
with a lot of primary turns probably also have a lot of secondary
turns, and this tends to result in a coil which operates at a low
frequency.  There is evidence that a lower frequency is effective
in producing longer sparks also.  Using a lot of turns may be less
important in larger coils which tend to have high surge impedances,
and lower frequencies even when using fewer turns, but this seems
to be unknown at this time.  Of course if too many turns are used
on any coil, it will increase the wire losses due to the high resistance
of the thin wire, and the losses will increase too much.  I discuss
these issues at my website
at: 
<http://hometown.aol-dot-com/futuret/page3.html>http://hometown.aol-dot-com/futuret/page3.html
click on the link for "efficiency theory".

John

>A friend of mine made a coil with about 24 turns.  It had 2 12 turn
>primaries in series.  I think he used 21 turns of it. The coil used a 12/60
>NST, RQ gap, 4.5" x 24" (28awg) secondary, a 4.5"x18" toroid.  One special
>note is that he uses for his MMC the cornel dubilier 940C, NOT 942C caps.
>They are rated .15uf at 2000v.  I was worried when he said he bought them,
>he didnt know there was a differece. But surprisingly, they worked
>extremely well!  Though we didnt run the coil for too long yet.  The coil
>made 38" sparks, and the coil seemed exceedingly wild in behavior.  I dont
>know that he really lost any efficiency, but i think he gained
>some.  Compared with other coils of the same input, and spark gap, there
>was an increase in spark output of about 6" at least, and the coil appeared
>more powerful overall.
>So maybe 18 turns isnt a bad thing!
>
>Steve Ward.
>
>
>