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RE: Does a "regulating" coil really waste energy?

Original poster: "Dave Larkin by way of Terry Fritz <twftesla-at-qwest-dot-net>" <teslaman15-at-hotmail-dot-com>

>Please correct me if I'm mistaken - I thought that the secondary Q was
>unimportant since streamer "losses" drive the Q into the dirt, but that
>maximizing primary Q was still desirable?

I am unsure to which part of my post your comment alludes to, however...

In a TC the primary's job is basically to dump as much of its energy as 
possible into the secondary asap, in a typical well quenched system this 
happens in 10-30 rf cycles.  This implies a low Q!

While textbook Q formulae for LCR resonance predict quite high primary Qs 
based on the L, C and approximate R, these neglect the Zsec, transformed 
back down to the primary.  The (relatively) low Qsec implies a low Qpri, in 
fact the only way to increase Qpri for a given value of Qsec is to decrease 
k, which is exactly what adding an off axis inductance does! (This does not 
mean we should all add massive off axis inductors, the penalty in increased 
spark gap losses, set against the dubious benefits of increased Qpri, 
doesn't look good)

I believe, the logic behind Greg Leyh's real time tuning attempt was to 
allow re-tuning on load, to compensate for the 'ion cloud' and streamer 
capacitance effects.  The relatively low system Q means that this had 
little/no effect (correct me if I'm wrong Greg).


>Gary Lau
>  -----Original Message-----
>From: 	Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent:	Tuesday, May 28, 2002 10:08 AM
>To:	tesla-at-pupman-dot-com
>Subject:	Re: Does a "regulating" coil really waste energy?
>Original poster: "Dave Larkin by way of Terry Fritz <twftesla-at-qwest-dot-net>"
>You are quite right.  The myth that off axis inductance directly 'wastes'
>energy is a hangover from the old days.  All it does is reduce k a little,
>which may lead to slightly increased spark gap losses beacuse of the longer
>More generally on the subject of real time tuning - Greg Leyh used a 
>litz wire tuner on his big coil, and quite a few others have tried other
>schemes since, no-one has reported any amazing benefits.
>The Tesla coil is actually a fairly low Q device (under sparking
>conditions), so these small alterations seem to make little difference.