# Re: [TCML] BPS Testing

Hi John,

I was looking at my input VA for the 140Vac situation. If I work the math backwards for the bps measured, my calculated current would be 11.6 rms amps. Strangely enough, the expected output spark length equates to 1.42 x sqrt(11.6*240). Why does 1.42 sound so darn familiar? When you first derived the JF formula, wasn't it 1.42? Probably nothing, but as soon as I saw the value, it felt very familiar.

In Javatc in the Transformer section, there is an input for "ballast current". It is meant to insert a measured value. If you insert your measured input draw value here, it will override the transformer current plate specifications and adjust for that particular current draw. So I simply set this current value until my static gap section achieved the measured 104 bps with my gap geometry (11.6A). At that point, I looked at the spark length in the static gap section (57.2") and then found 57.2/sqrt(16.2*240) = 1.42 and that's when familiarity set it. Probably just coincidence.

Unfortunately, I didn't pay attention to spark lengths. Once I flipped the switch to run the coil, I ran back in the house (turning off the garage light in the process) and hit the record function on the pc (I then watched events unfold in real time on the pc). But, I could "hear" some "good" gap and spark firing happening. I'm certain about 50" was real, but can't say if it reached 57" or not.

Bart

bartb wrote:
Hi All,

Today I ran the coil at 140Vac and retested bps.

I also measured input current at both 120Vac and 140Vac while running the coil.

During the 120V measurement, current fluctuated between 12.7A to 13.7A = 13.2A average = 1.58 kva. During the 140V measurement, current fluctuated between 14.6A to 15.8A = 15.2A average = 2.13 kva.

For the BPS Testing, I ran similarly as before, except this time I got rid of the switching power supply and simply installed some 9V battery's on the board to power the light transducer.

The total recording time is 11.3263 seconds. Total breaks were 1176. BPS is then 104. So still pretty low.

Photo of the setup: http://www.classictesla.com/temp/light%20transducer%20board.JPG Photo of the gap: http://www.classictesla.com/temp/spark%20gap%20fiber%20optic.JPG

The sample rate was set to 2500/s, so time divisions are 0.008 seconds.
http://www.classictesla.com/temp/bps_1560_140VAC.gif

Here's the various files (windaq, raw csv, filtered bps excel file):
http://www.classictesla.com/temp/1560-140-1vac.WDQ
http://www.classictesla.com/temp/1560-140-1vac.CSV
http://www.classictesla.com/temp/1560-140-1vac.xls

Take care,
Bart
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