Re: Spark Gap VI Scope Capture

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

Original poster: "K. C. Herrick by way of Terry Fritz <teslalist-at-qwest-dot-net>" <kchdlh-at-juno-dot-com>

Terry,

Most detailed & interesting!  But what are the >units< of resistance in
http://hot-streamer-dot-com/temp/2003-05-19-11.jpg?  If ohms, then such a gap
as you tested is n.g. for low-voltage primary circuits.  If the gap was
of some length e.g. 1/4" or thereabouts, can you make the same kind of
test for, say, a 1/16" gap?

Do we infer that the -11.jpg image is for the current shown in
http://hot-streamer-dot-com/temp/2003-05-19-07.jpg?

Also, what are the vertical-axis units in the "spark" images?

I'm trying, of course, to get an understanding of what the measured
resistance might be for running thousands of amperes through a very
closely-spaced gap.

Ken Herrick

On Mon, 19 May 2003 19:05:56 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
 > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >
 > Hi again All,
 >
 > I just added the resistance graphs of the gap here too:
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-10.jpg
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-11.jpg
 >
 > Cheers,
 >
 >         Terry
 >
 > ----------------------------------------------
 >
 >
 >
 > Hi All,
 >
 > I figured out this way to look at the voltage across and the current
 >
 > through a spark gap:
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-01.jpg
 >
 > It is just a tank circuit charged with a high voltage DC power
 > supply.  One
 > side of the gap is grounded through an RF ground.  A 100:1 Pearson
 > 101
 > current monitor and a TEK6015 probe send the voltage and current to
 > a
 > scope.  The power supply and scope probes and circuits are
 > separately
 > grounded and well isolated so it is pretty safe for the scope.  It
 > looks
 > like this:
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-02.jpg
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-03.jpg
 >
 > The capacitor is really 24nF and the coil is 55uH for a resonant
 > frequency
 > of 138.5kHz.  The firing voltage was set at around 3000 VDC.
 >
 > The scope waveform looks like this:
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-04.jpg
 >
 > If you pull it into Excel it is clearer:
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-05.jpg
 >
 > One can add an instant power calculation:
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-06.jpg
 >
 > Oddly, at times the gap seems to be absorbing power!?
 >
 > Just the current looks like this:
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-07.jpg
 >
 > Note the little pre-burst in the beginning.  These are very common.
 >
 > The Excel file is here:
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-08.xls
 >
 > The raw data file from the scope is here.
 >
 > http://hot-streamer-dot-com/temp/2003-05-19-09.CSV
 >
 > The current waveform had a little offset to it, so I adjusted for
 > that in
 > the above.
 >
 > This is just one spark, but it is pretty typical.
 >
 > Cheers,
 >
 >         Terry
 >
 >
 >
 >