Re: Tesla Coils


Let's think about this question.   You have obviously been mulling this 
matter over a bit.  That the sign of a first rate coiler.   If the primary 
is tuned to a frequency X then it will ring up to this frequency only.  Now 
the secondary with its top loading also has a frequency of resonance which 
should ideally be X also.  If, while firing, the secondary has corona and an 
ionized shell about it, this loads the secondary or effectively shifts its 
frequency a bit.  (always downward)   If the primary is tuned to X and the 
secondary is now tuned to Y (lower loaded frequency) more  primary turns are 
required regardless of whether the primary sees the secondary or is coupled 
to it during subsequent firings.  Otherwise, the primary is just not going 
to do its job very well.

 I somehow get the impression that you might think that the sparks and 
illuminated corona must be at full tilt to create this frequency shift. 
 Ionized air, especially around a big machine, has a long lifetime  (100's 
of milliseconds)  and sparks are not necessary to lower the secondary 
frequency prior to the next "pop" if the machine has been on a few moments. 
  Machines with large terminal loadings are particularly sensitive to this 
effect.  The best one can hope for is to actively fine tune the system under 

Whether the primary circuit sees the secondary (bad quenching) or not will 
rarely matter to the secondary and the ion cloud, other than to impede best 
performance through poor quenching.  On big coils with large loadings, a 
full extra turn is most often needed to bring the operating system into 

Richard Hull, TCBOR
From: tesla
To: Tesla-List-Subscribers
Subject: Re: Tesla Coils
Date: Monday, April 22, 1996 9:00AM

>From MALCOLM-at-directorate.wnp.ac.nz Sun Apr 21 14:42 MDT 1996
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From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
To: mrbarton-at-ix-dot-netcom-dot-com (Mark Barton)
Date:          Mon, 22 Apr 1996 08:21:45 +1200
Subject:       Re: Tesla Coils
Cc: tesla-at-grendel.objinc-dot-com

cc. tesla-at-grendel.objinc-dot-com

Hi Mark and others,
                   An extra note on the discussion of primary-
secondary matching in the coil. I realized over the weekend that
there is a strong piece of evidence that I had previously overlooked
to support the idea that the coil must be considered a coupled system
during secondary spark production. At higher power levels, it is
found that the frequency the primary is tuned to must be lowered
beyond what the scope shows is correct. I have heard figures ranging
from 1/4 extra primary turn to a full extra turn. This would not
be necessary UNLESS the primary can "see" the extra secondary capa-
citance caused by the secondary corona/sparks. It can only do this
while the primary gap is firing. QED.