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RE: [TCML] BPS Testing

Hi Bart,

Could it be a wide gap setting causing such a low break rate. I assume
though that would rely on resonant charging of the cap and I don't think
that cap is resonant is it?


Colin Heath
07748 662531
MEC-Solutions Ltd
Engineering Solutions for Industry
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of bartb
Sent: 11 March 2008 01:20
To: Tesla Coil Mailing List
Subject: Re: [TCML] BPS Testing

Hi Gary,

I failed to state the test configuration. Here it is:

Sec= 4.5" x 21.81", 24Awg, 895 turns.
Pri= 7.5" x 16.5", flat spiral, 9 turns, tapped at 8.5
Pri Cap= .0188uF (this is 1.77 x the res cap size)
Toroid= 6.25" x 21" (minor and major diameters)

Gap= RQ style, 6 tubes (1.25" Diam., .050" spacing, 0.25" total gap 
width) w/lots of air cooling.

NST= 2 x 15/30's in parallel (no variac, no safety gap, 120Vac input 
directly at wall plug). Identical Franceformers.

Spark lengths were not as good as my main modified NST, but ok at 40" 
average free air sparks. I wasn't doing a spark length test, but did 
notice the sparks relative lengths and a couple strikes to my air 
compressor 45" from the toroid.

The BPS is low. The 12.7 second test confirmed 80 bps. Given the rate of 
charge, cap size, and arc voltage for gap geometry, I calc'd 70 bps for 
this static gap. I can understand the 80 bps value. Also, I could "hear" 
the bps rate was low and this test confirmed it.

As you know I've had a problem with the high bps rates stated. In our 
near last conversation on this topic you asked me "have you ever 
measured it?". Well, now I can say "yep".

I'm curious more about your measurements and setup at this point to try 
to explain the high bps you measured. Either current is higher (modified 
NST? or maybe the gap itself is the cause?). I don't know, just 
stumbling in the dark to explain it. There has to be a logical reason 
for it and if it was something seen by all coils, then I should have 
measured at least 120 to 150 bps, but I didn't. So from my perspective 
at this point, not all systems will see a high bps to what is predicted.

Take care,

Lau, Gary wrote:
> Hi Bart,
> I missed the basic test configuration that you're using.  Two 15/30's, but
what size cap?  Gap geometry?  Did the coil perform well?  82 or 70 BPS
seems low for a well performing coil.
> Regards, Gary
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