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Re: [TCML] Half Wave Coil

Normally it is best to wind one coil clockwise and the second coil
counterclockwise --- similar to the construction of an X-ray transformer.
In this technique one coil will hit a positive polarity while simultaneously
the opposite coil hits a peak negative polarity.  The produces max potential
between the two ungrounded output ends of the coils at the same moment in

When winding a 1/2 wave resonator the same techniques apply as winding a 1/4
resonator with regard to coeff. of coupling.  You shold leave 1-2 inches at
the base of each coil at the point where the Archemedian spiral circles your
coilform. This loosens up the coupling slightly and prevents overcoupling.
You may wish to experiment a bit, but with an 8" dia coilform I would
suspect 2.50 inches to work best.

You can check all of this out in JAVATC.  Just use one winding and treat it
as a single coil and the coeff. of coupling will appear. Keep in around 0.1to
0.13 range for best output spark.  You can mathematically adjust the inner
coil radius of the primary until you achieve the proper coupling.

You could also use a small 6" inner tube on which two separate 8" tubes
slide.  Make the 6 inch tube approx 12-14 inches long.  This slider will
allow you to adjust your coeff. of coupling for best spark output.  After
you find the sweet spot for best output spark, just glue the tubes in

In many cases a loose coupling factor will produce much better output sparks
than tight coupling.  In many coils that I have tested it seems a 0.10 to
0.13 k factor produces the longest output sparks.

Happy sparking,

Dr. Resonance

On 3/15/08, Jim Mora <jmora@xxxxxxxxxxx> wrote:
> Hello All,
> I am thinking of building a halfwave resonator. The dimensions I am
> thinking
> about are 8.25" pvc .125"wall irrigation pipe 72" long former. I have a
> 14400 5KVA 240v potential transformer and a Maxwell .1uf 50kv cap (I have
> 2
> of these) and would wind with ~ 10 lbs of 22awg ~5000ft. I also have a 12"
> G10 x 8 arsg with a variable speed dc motor and controller with 1.5" .125
> W
> electrodes.
> There is a lot I don't know about these. Is it wound the same direction
> like
> a double long 1/4 wave the entire length? I seem to remember the primary
> is
> designed to resonate at 2x FR of the whole coil length. I would use a 12"
> wide solenoid with a foot or more of PVC overlapping on each side of
> center.
> There doesn't seem to be very many turns indicated so I suppose .5 Cu tube
> would be ok?... I can get this former in .125" wall as well, in fact I
> have
> 6 feet of it.
> I also seem to remember there is to be a gap under the primary... is this
> to
> tweak the coupling? What is the best gap for such a system? How does the
> efficiency of these compare to a regular coil? Since the arc strikes 180
> degrees out of phase and connects, one of this size and power would have a
> roaring arc, yes?
> I have decided to abandon the 12" 1/4 wave I was going to build in favor
> of
> a 22-24" if I can find a suitable former since I now have access to a very
> favorable steel building with tall roll up doors and a large concrete area
> to roll out into. The electricians I am working with can get me 16 AWG at
> cost in extended lengths. On these big coils is stranded PVC ok or is
> solid
> better?
> Thanks All,
> Jim Mora
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