Original poster: "C. Sibley" <mailto:a37chevy@xxxxxxxxx><a37chevy@xxxxxxxxx>
Bart,
Thanks for confirming my belief. I used JAVATC and
designed my primary for a coupling of .14 - that
seemed safe. If I we to do it again I'd raise the
primary even higher and make the secondary height
adjustable - but this little coil was supposed to be a
quick experiment (it got a little out of hand). When
I get a chance I'll perform the coupling measurement
as you suggest.
Great explanation for measuring the coupling, You
should add it as a permanent addition to your web
page.
BTW: My coil tuned in less than 1/4 turn from where
JAVATC predicted. Kudos...
Curt.
--- Tesla list <mailto:tesla@xxxxxxxxxx><tesla@xxxxxxxxxx> wrote:
> Original poster: "Barton B. Anderson"
> <mailto:bartb@xxxxxxxxxxxxxxxx><bartb@xxxxxxxxxxxxxxxx>
>
> Hi Curt,
>
> The coupling will be maximum when the primary is
> center to the
> secondary. As the primary is moved away from the
> center toward one of
> the ends of the coil (either end), the coupling will
> decrease. As the
> primary is moved even further below or above the
> primary
> (perpendicular), the coupling continues to decrease.
>
> This occurs because mutual inductance is greatest
> when the coils are
> at their closest proximity, which for a 2 coil Tesla
> configuration is
> when the primary is centered to the secondary.
>
> As to your specific question:
> Let's say you start with a config where bottom pri =
> bottom sec (as
> you mention). You will have "some" coupling value.
> As you move the
> primary up the coil, the coupling increases. When
> the primary is
> center to the secondary, it will be maxed out. As
> you go past center,
> the coupling will begin to fall as you near the top
> end.
>
> Your friend is wrong. Prove it to him (measure it).
>
> I drew up a well known measurement technique and put
> up here (since
> my ascii art sucks).
>
>
<http://www.classictesla.com/download/M_and_k_Measurement.gif>http://www.classictesla.com/download/M_and_k_Measurement.gif
>
> Maximum coupling is a point I need to know for the
> program, it is not
> "best" for obvious reasons. For a program, I need to
> know when to
> stop raising the the primary to achieve a coilers
> "desired" coupling.
> Imagine if someone put in a coupling value of 1 and
> the max possible
> was say only .25, well, obviously, I need to know
> when to stop. This
> is "my" purpose for realizing and identifying a
> geometry's maximum
> possible coupling.
>
> Your primary is well below the secondary. As you
> raise it (small 1/4"
> to 1/2" increments), your coupling "will" increase.
> Because it is
> helical, it will have a significant effect on
> coupling due to it's
> geometric relationship with the secondary. Probably
> sooner than
> later, you will begin to notice periodic racing
> sparks. As soon as
> that begins, you should try to retune before
> adjusting the primary
> back down (to maximize performance). The primary
> itself will change
> the secondary resonant frequency slightly, so
> retuning may improve
> the racing spark problems and allow a higher k.
>
> Take care,
> Bart
>
> Tesla list wrote:
> >Original poster: "C. Sibley"
> <mailto:a37chevy@xxxxxxxxx><a37chevy@xxxxxxxxx>
> >
> >Mine is a solenoid (helical) primary. Back to the
> >original question, if the secondary starts below
> the
> >botton of the primary, does that increase coupling,
> >and would it help comphensate for the loose
> coupling
> >die to the oversize primary? According to JAVATC
> it
> >does, but my friend insists that I would get less
> >coupling...
> >
> >--- Tesla list
> <mailto:tesla@xxxxxxxxxx><tesla@xxxxxxxxxx> wrote:
> >
> > > Original poster: "D.C. Cox"
> >
> <mailto:resonance@xxxxxxxxxx><resonance@xxxxxxxxxx>
> > >
> > >
> > > Lay a straightedge across the top of your
> primary if
> > > it is a flat spiral ---
> > > this is the horizontal plane. This does not
> apply
> > > to solenoid type primaries.
> > >
> > > Dr. Resonance
> > >
> > > > > I bet you need this size sec approx 1/2 inch
> > > above
> > > > > the horizontal
> > > > > plane of the pri
> > > >
> > > >What do you mean by horizontal plane of the
> > > prima.........