RE: Neon Sign Transformers (was: spark length formula needed*)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi John,

I checked against the computer models of my big coil.

http://hot-streamer-dot-com/TeslaCoils/MyCoils/BigCoil/BigCoilSCH.gif

The true RMS current and voltage into the NST are 10.23 A at 113.2 V  The
VA is 1158.

The output is 81 mA at 12845 V for a VA of 1040.  So the input VA is higher
than the output.

However, if I look on the other side of the power factor cap (200uF) I see
only 7.77 A which gives an input of only 880 VA.

So with a power factor cap I can have 880VA in and 1040 VA out.

I would not be surprised of using an RC load if you could get a higher "VA"
out than in under various conditions.  A simple cap on the output that was
resonant my give say 80kV at 60mA for a giant VA of 4800 but the input may
only see a VA of 1000.  Even with a non-resonant cap you would see a very
high VA on the output (a pure reactive load provides maximum VA) with
perhaps a much lower VA in.  In the resonant case, the difference could be
dramatic.  Maybe 5X if the NST does not blowup.

There are further possibilities given the looser coupling of an NST...

Cheers,

	Terry

At 11:38 PM 12/23/2001 -0800, you wrote:
>
>Jim, All -
>
>The Tesla coil circuit is an RC type of load on the NST secondary. My tests
>of NSTs indicate that under certain conditions the VA input to the NST could
>be smaller than the VA output to the TC. Has anyone ever checked this
>possibility for a Tesla coil?
>
>John Couture
>
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