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Re: [TCML] JAVATC output



Hi Robert,

I was brain dead in my statement below (actually thinking about something else while doing your numbers). Then I realized .04uF with a 15/30? No, bad bad bad! So I reply again with a completely better look at your coil. You didn't have a top load at all. Turns were ok for that. But the .04uF cap is way too large for a 15kV 30mA supply.

You really need to have the bps at least 2 x Hz, so 120 bps in your case, the cap needs to get down to at least 0.008uF (from .04uF). That's a huge drop. Causes your turns to increase to near 14 with the same coil. But you also need a top load of some type. Given the low power, best the top load is very small in the minor diameter.

But really, your nee to rethink this coil altogether. There's nothing wrong with a big coil, but you must have the power supply that can charge the cap at a decent rate. This means you need to identify the NST power and cap size, then figure out the coil to serve the spark length expected (that is very basic common sense with sparking coils).

Look at bps in the static gap. Set the gap so that the arc voltage is only slightly below the charging voltage. Then increase the cap size until you at least achieve near 120 bps. It is actually even better to just look at the LTR value for the cap in the transformer section and use that value or something near. Then, go after the coil design trying to keep the h/d between 4 and 5. Good to use a toroid and with a minor diameter equal or slightly larger than the secondary diameter and that the major diameter is about 4 times the minor diameter. From that, you can look at the primary needed. Keep coupling within or even slightly below the recommended coupling. Those are the basic design parameters.

If you need off-line help, shout at me off-line.

Take care,
Bart

bartb wrote:
Hi Robert,

I looked at your coil. Your lead length is 16 and I think you meant 0.16. Anyway, the coil will need a top load. Have any game plans for that? Given the coil is very short and wide with h/d of 2.27, your likely to get arcing to the primary with enough power. But power is something that is obvious here. It's only a 15/30 NST powering a very large coil. The coil portion isn't so much the issue as is the capacitance of .04uF. Not a big problem, but it would be nice to know your top load as this will affect the results. So, what top load did you look at? I notice the coil is out of tune by factor of 4, so I assume you modeled a top load and forgot to include it.

Bart

Robert Davies wrote:
The gap is a guess at this point as I'm not sure yet if I'm going rotary or static.
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