Re: Arc Over Between Secondary and Primary Coils (Tuning?)

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Nolan - 

Tesla list wrote: 
>
> Original poster: "tmoore by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <tmoore-at-erie-dot-net> 
>
>     When tuning my coil how am I suppose to know when I have it exactly in 
> tune? Can I tell by the behavior of the streamers?  What should they look, 
> sound like and behave?

There are many methods. I like to measure with a scope or similar. If tuning
for streamer length, then I use a ground rod and tune until I can acheive the
longest arc at 1/2 power. I then tryit at full power. If I get racing arcs or
strikes out to the primary, I'll adjust coupling by raising the secondary up
until it stops. I'll then go through the tuning to a ground rod one more. 

Racing arcs can occur from an out of tune coil and/or from too high of
coupling. Each coils a little different but they all have the same basic
behavier. When you can run at full power with sparks coming only from the top
terminal, then your in tune for sparking. Top terminal sizing makes a
difference in field control. This is best accomplished from trial and error
with different sizes. Typically, we only build one or two top teriminals and
call that "good enough". 
>
> BTW it is a flat primary coil and I believe its taped at the 5th turn.

Thanks for letting me know. I reran with a 12.75" secondary length. 

ETesla6 = 613kHz = 41% reduction in effective top C. When I ran ETesla6, I ran
with the bottom edge of the toroid even with the top of the secondary winding.
Toroid positioning will change Fres and tuning of course. 

At this frequency, JavaTC shows tuning at 3.1883 turns with this primary
(assumes measurements are correct). (If you ever have a primary that kind of
vary's spacing between turns, simply measure the ID and OD, then adjust the
spacing until the OD in a program like JavaTC matches your measurement). 

I took the liberty of putting your coil into the JavaTC database. You can goto
JavaTC and type your name in lower case = nolan = this goes in the input box
next to the "Retrieve Coil Data" button. Once your name is typed, just click
the button and your coil inputs will be loaded and calculated. 

 <http://www.classictesla-dot-com/java/javatc.html>http://www.classictesla-dot-com/
java/javatc.html 

Mutual inductance is 13.18uH and coupling is 0.1134 in JavaTC which looks
pretty good. My guess is the tuning is off. Here is Acmi's output for mutual
and inductance and K for reference. 

PRMY.h2|    PRMY.L| PRMY.R|    SCNY.L| SCNY.R|PRMY-SCNY.M|PRMY-SCNY.K 
 -3.000|   1.33 uH|   0.00|6079.06 uH|  31.67|    7.01 uH|     0.0781 
 -2.000|   1.59 uH|   0.00|6079.06 uH|  31.67|    8.60 uH|     0.0874 
 -1.000|   1.94 uH|   0.00|6079.06 uH|  31.67|   10.68 uH|     0.0982 
  0.000|   2.22 uH|   0.00|6079.06 uH|  31.67|   13.16 uH|     0.1134 
  1.000|   1.94 uH|   0.00|6079.06 uH|  31.67|   15.64 uH|     0.1438 
  2.000|   1.59 uH|   0.00|6079.06 uH|  31.67|   17.70 uH|     0.1800 
  3.000|   1.33 uH|   0.00|6079.06 uH|  31.67|   19.27 uH|     0.2146 

Take care, 
Bart 
>
> Sincerely, 
> Nolan Moore 
>
> ----- Original Message ----- 
> From: Tesla list <tesla-at-pupman-dot-com> 
> To: <tesla-at-pupman-dot-com> 
> Sent: Saturday, March 16, 2002 2:25 PM 
> Subject: Re: Arc Over Between Secondary and Primary Coils 
>
> > Original poster: "boris petkovic by way of Terry Fritz 
> <twftesla-at-qwest-dot-net>" <petkovic7-at-yahoo-dot-com> 
> > 
> > 
> > > Hi Nolan, 
> > > 
> > > If the tuning is off, you can get some pretty long 
> > > primary to secondary 
> > > arcs (like a foot long!).  You may want to try 
> > > adjusting the tuning if all 
> > > else fails. 
> > > 
> > > I recently saw this problem and it is amazing how 
> > > long the primary to 
> > > secondary arcs can be if the coil is out of tune. 
> > > 
> > > Cheers, 
> > > 
> > > Terry 
> > > 
> > --- 
> > Yes.Needless to say ,it's more likely to happen 
> >  when Fp>Fs than in Fp<Fs case. 
> > (Fp..resonant F of primary ,Fs ...res F of secondary) 
> > 
> > regards, 
> > Boris 
> > 
> >