Re: [TCML] breakouts and a picture

[bartb <bartb@xxxxxxxxxxxxxxxx>]

No problem Simon,

I ran the numbers in Javatc also with the correct primary height. The 
coil is basically 200kHz with top terminal installed. Your data calls 
out the .02uF cap size (which is not a great cap size here as it is too 
damn close to transformer resonance). But, with this .02uF cap size, the 
coil should tune in at 7.5 to 8 turns on the primary. There is a 
problem, the coupling is rather low at .085. You can raise the coupling 
to roughly 0.12 as a good place to start by reposition the relative 
heights of the primary and secondary either by lowering the secondary 
further down into the primary or raising the primary up. However, there 
is also a problem doing that with your coil. In order for 0.13k, the 
primary would need to be positioned at 59.8cm above ground (versus the 
current 45cm). This really cuts down on your toroid to primary distance, 
so I would recommend another option in this specific case.

That is to add inner turns. It looks like your were playing it safe with 
the primary to secondary distance at a large 9cm from edge of sec to 
edge of pri. You can safely reduce this distance down to 3.5cm without 
sec to pri flashover on your particular coil. I've done this before 
(adding a turn or two on the inside of a primary). Simply use the same 
tubing size. Where the two tubes butt together, insert a non-insulated 
butt-splice that fits snug on the inside between the two primary ends. 
Then just sweat solder the joint.

Anyway, with a primary height of 48.3cm, inner radius of 9.5cm at 8.7 
turns, your coil will be tuned to 200kHz with a coupling of 0.12 and 
should help out quite a bit with sparks. I'll also foward my JTC output 
to you off-line for reference.

Take care,
Bart



Simon Dodd wrote:
> I have just seen the help file, yes the primary height is 45, sorry 
> about that!
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