Re: Spark Gap VI Scope Capture

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

Original poster: "Peter Lawrence by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Peter.Lawrence-at-Sun.COM>

Terry,
Jim,
     great experiment, and real nice looking data.

I was wondering why the volts plot was not centered around zero like the
amps plot is, and why it has a net drift. I was thinking this could be the
NST 60-Hz voltage superimposed on the 100-KHz primary resonance, and we
are seeing just a tiny fraction of a 60-Hz cycle. Perhaps if you caught
different firings of the gap you would see the volts offset the other
way half the time.

-Pete Lawrence.



 >
 >Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
 >
 >I've done some quick analysis..
 >First, if you decimate the data by 10 (and appropriately low pass filter
 >before decimating (I used matlab.. which filters at 0.8*Fs/2) you can start
 >to see some real structure.
 >
 >There's a "low frequency" exponential looking offset in the waveform that
 >extends over the entire waveform.  If you look at the expanded view inside
 >the discharge, you can see that the voltage is essentially constant during
 >the spark (which is sort of what you expect.  Assuming that the constant
 >voltage is straddling the real number, it looks like a voltage drop of
 >about 60-75 volts is a good representation of the "steady state part of the
 >discharge.
 >
 >figures can be found at:
 >
 >http://home.earthlink-dot-net/~jimlux/images/vi1.png  - expanded view of
 >decimated data
 >http://home.earthlink-dot-net/~jimlux/images/vi2.png  - all data, decimated by 10
 >
 >
 >At 12:32 PM 5/20/2003 -0600, you wrote:
 >>Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >>
 >>Hi Jim,
 >>
 >>Looks like this:
 >>
 >>http://hot-streamer-dot-com/temp/03-05-20-01.gif
 >>
 >>I tried over smaller times spans but it did not really seems to show much.
 >>
 >>Cheers,
 >>
 >>         Terry
 >>
 >>At 07:03 AM 5/20/2003 -0700, you wrote:
 >>>One might want to plot V vs I for the gap... While time domain behavior is
 >>>interesting, I'd be interested to see the VI characteristic for the gap...
 >>>
 >>>
 >>> > I have no idea where this voltage offset comes from but it seems to
 >>> > certainly have an effect on quenching here!!
 >>> >
 >>> > Much to ponder in this little spark ;-)))
 >>> >
 >>> > Cheers,
 >>> >
 >>> > Terry
 >>> >
 >>> >
 >
 >
 >
 >