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Re: loose coupling
Subject:
Re: loose coupling
Date:
Mon, 17 Mar 1997 08:07:06 -0500 (EST)
From:
tesla-at-america-dot-com (Bob Schumann)
To:
Tesla List <tesla-at-pupman-dot-com>
Robert,
You are correct that the voltage transformation is due
primarily to resonance rise and not turns ratio. I have done
the equations for mutual inductance (M) and the coefficeint
of coupling (K) and applied these to my coil but I understood
more just by observtion of what the coupling did, not just
a bunch of formulas. When my coupling was loose (for the formulas
sake - say .12), I had longer discharge lengths but at a
sacrifice of current. When I was doing Ion motor experiments,
I found that I could loosen my coupling to the point where there
was not enough current to turn the motor. When I had tighter
coupling, I had thicker discharges but they were overall shorter
than the loose coupling ones. The ion motor worked well with
tighter coupling as there was more of a current factor.
I have gone to both extremes - on purpose. When the coupling
became to loose, the whispy discharges looked just like the
coil was out of tune. When I made coupling very tight, I had
such a visible field between the primary and secondary and
I had strikes that went up the side of the secondary, which
is not a good thing! I photographed the over-coupling and you
can see them in the small coil operation section of my web
page. I caught a secondary strike on film. I believe that the
best coupling you can get on a classic Tesla coil is about k=.25
Tesla maginfiers overcame this limitation abit as I think that
I have read couplings of about k=.60 (Is that right you guys?)
I have not tackled a magnifier yet so that may be a guesstimate.
The International Tesla Society has a catalog with lots of
books to choose from. I would not judge which is a better
book. There are many of them I have not read.
Hope this helps some,
Bob Schumann
tesla-at-america-dot-com
http://www.america-dot-com/~tesla