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Re: Magnifying Coil

In a message dated 5/10/00 9:43:58 AM Pacific Daylight Time, tesla-at-pupman-dot-com 
writes:

> Original Poster: "Dan Kunkel" <kunk77-at-juno-dot-com> 

> I will list the important details pertaining to maggy's as I
>  understand them to be...please correct and add if you can.
>  
>  1) Really tight coupling between pri/sec

Dan,

The tightness depends on the relative amount of inductance in
the secondary and resonator.  As the secondary inductance is
decreased, the pri/sec coupling will need to be increased to keep
the overall k constant.  If the overall coupling is too tight, you'll
get racing sparks, flashovers, corona problems, etc, the same as
with a classic TC.  It is best to design the coil so you can adjust the
k for best performance.

>  3) Pri should be a verticle helix extending almost the whole length of
>  the secondary

Usually the primary is about 1/2 the length of the secondary or less.
If the primary extends too far towards the top of the secondary, you'll
get horrible flashovers.

>  4) Sec is very low inductance and low impedence (space wound heavy gauge
>  stranded wire)

The secondary is often about 1/4 the inductance of the resonator, it
can be more or less than that of course.  Usually close wound pvc
insulated wire is used.  There's no advantage to using stranded wire.

>  5) Sec should should have a fat ratio...~1.5:1

This is to help keep the coupling tight, it's not a critical spec though.

>  6) Sec should be twice the operational frequency of the tertiary

This has no bearing on the performance.

>  7) Tert should be high inductance and high impedence (close wound magnet
>  wire)

Basically yes, but pvc insulated wire can be used in you can get enough
inductance.

>  8) Tert should be heavily toploaded (and be half the freq of sec coil)

The amount of topload will vary with the power input, etc as in a classic
TC.  The frequency relationship does not apply.

>  9) Tert should have a ratio of ~2:1

It doesn't make much difference.

>  10) Use a very fast break rate in the spark gap

This is incorrect.  There's nothing about a magnifier that demands
a faster break rate than a classic TC.  I've seen the best results at
a low break rate in both classic and magnifier TC's.

>  11) Connect sec and tert coils 6'-9' feet apart and use a loss conductor

You can put them farther apart or closer and it won't matter either.  You
can even put the extra coil on top of the secondary, and it will still work
the same (basically).  (Same spark length.)
>  
>  So if there are no real advantages secured from a magnifiying coil, then
>  why build them? Maybe for looks, or something different, or to save a
>  little space?

The way that magnifiers have been built there are not many advantages.
Yes, the look is different, it may have some space advantages in some
situations, etc.  The extra coil can be made quite short for the spark
lengths that are produced.  There is a special way to build a magnifier 
that requires a careful arrangement of inductance and capacitance
values in the coils, this method is explained by Antonio Carlos M.
DeQueiroz at his website, I think he posted the URL recently.  This
method may give a slight advantage because it traps all the energy
in the extra coil at one time, and the coil may benefit from the smaller
amount of Cself in the extra coil.  But this method of construction has
never been tested by coilers.  I've been wanting to try it but never got 
around to it, so much other TC research to do.

Have fun and be safe,

Cheers,
John Freau

>  
>  Thanks,
>  Dan