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Re: [TCML] Refurbished Coill



Hi Ruben,

I ran Javatc on your coil specs.

http://www.classictesla.com/temp/rubenpeters.txt

With the primary even with the bottom of the secondary, coupling is .122 and a good value (Javatc recommends .123 on this coil). Javatc has the ability to accurately account the toroid capacitance and it's affect on the coil overall, so the resonant frequency showed 449 kHz when all is said and done for a primary tune at 7.75 turns using .0111uF. The cap value is good.

The primary to secondary clearance is close and could be problematic. You might want to start the primary at 25mm distance to be safe. Javatc recommended 1.2". The toroid size looks good for the coil size. You might get away with a little larger radius, but difficult to say.

Take care,
Bart

Ruben Peters wrote:
Hello All,

I've recently re-joined the list, and am getting back into coiling after a 3
year hiatus, anyway, I'm aiming to refurbish my first coil-to be sturdier
(initially a hot glue and tape job), and a better performer (originally
around 9" sparks with  9.2nf wine bottle caps, and what I think was over
coupling due to the occasional racing spark and the 40 degree, 7 turn
conical primary).

I plan to use my original secondary coil, and 12/30 NST, with a new MMC and
flat primary setup.

For the spark gap, either a Multi-segment static gap, or I'll try out some
gas surge arrestors (Im aiming for a bit of noise suppression)

 The Planned specs are:

Transformer/Cap:

12/30 NST

11.1 nf LTR Cap

Primary (wintesla 5 and Tesla Coil CAD 2) :

Primary capacitance : 0.0111uF

Primary resonant frequency : 428.89kHz

Primary conductor diameter : 0.25in,6.35mm

Primary turn to turn spacing : 0.25in, 6.35mm

Spacing between the secondary and the inside turn of the primary : 0.59in,
15.00mm

The primary will need to be tapped between turn 8 and turn 9 to form a
resonant circuit at 428.89kHz

Inside Diameter: 3.346in 85mm

Total Primary Diameter: 16.35in, 415.29cm

Length 32.66ft, 10m

(This gives 13 turns total with the aim of re-using the primary for the
inevitable next coil)

Secondary: Secondary Wire Diameter (IN) 0.0113, Wire Gauge 29.0000
Secondary Coil Total Outside Diameter (IN) 2.1650  , 55mm

Length of Secondary Coil (IN) 10.5000  , 265mm

Secondary Turns/Inch 86.1508

TOTAL TURNS : 878
Secondary Coil Calculations (wintesla 5):

Inductance (mH) 7.86 Medhurst K 0.78 Radius (IN) 1.08 Circumference (IN) 6.80 Wire Length (FT) 497.33 Self-Capacitance (pF) 4.31 Secondary Frequency (kHZ) 865.00 Secondary Frequency W/Terminal C (kHZ) 428.89
Toroid:

Top Load Capacitance (PF) 13.26pf approx

Sphere Radius/Toroid Tube Diameter (IN) 2.5000  ,63mm

Toroid Diameter Tube Center-to-Center (IN) 10.0000 ,254mm

Of course I have a few questions, so any help/suggestions on the above are
very much appreciated.

1)      Will the 15mm clearance between primary and secondary base be
sufficient (the winding starts around 2cm up the secondary)?

2)       Any advise on coupling for this system (the notion that my previous
setup was over coupled is just a hunch, backed by the occasional racing
spark)?

3)      Am in in the ballpark for an optimum torroid size?

4)       Finally, does anyone know a good MMC source in Australia?

Thanks again for any input

Ruben

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