Re: Spark Gap VI Scope Capture

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

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

Hi Jim,

I tuned in the inductor to less inductance to get higher currents:

http://hot-streamer-dot-com/temp/2003-05-20-01.jpg

http://hot-streamer-dot-com/temp/2003-05-20-02.CSV

Still have the dip in the average voltage level here at ~125 amps too.

Sure seems odd that the voltage would have this offset and I see that it 
did not return to zero in this faster time frame...  Hmmmm...

I pulled out the "fabulous" Jennings vacuum capacitor divider HV probe and 
go this:

http://hot-streamer-dot-com/temp/2003-05-20-03.jpg

http://hot-streamer-dot-com/temp/2003-05-20-04.jpg

http://hot-streamer-dot-com/temp/2003-05-20-05.CSV

A ton of odd noise now (not sure what is "true"...)  But look how straight 
the average voltage level is!!!

So I pulled out the Terry's plane wave antenna and pointed it the the probe 
top:

http://hot-streamer-dot-com/temp/2003-05-20-06.jpg

http://hot-streamer-dot-com/temp/2003-05-20-06.jpg

http://hot-streamer-dot-com/temp/2003-05-20-08.CSV

Still NOT seeing that average voltage dip...

I note you mention that "maybe the voltage probe system is a bit 
overcompensated".  Hey... I "wonder" how the probe compensation could 
possibly be "off" :o)))

http://hot-streamer-dot-com/temp/2003-05-20-09.jpg

I sure hope "R4" does not need any adjustment ;-)))

Cheers,

         Terry




At 01:59 PM 5/20/2003 -0700, you wrote:
>Once I low pass filtered/decimated the data, it looks like V and I line up 
>quite nicely.  The V transients are right at the I zero crossings.
>
>The overall baseline shift during the pulse is interesting.  I wonder if 
>it's just representative of some AC coupling.  Essentially you've got 
>3000V, then zero volts, (ignoring the LC ringing and transients)and maybe 
>the voltage probe system is a bit overcompensated so you're getting 
>negative overshoot.
>The overshoot looks like about 10%, peak.
>
>The little spikes at the beginning of each conduction interval might be 
>the resonance of the spark gap wiring etc, that you observed in frequency 
>domain several years ago. The overshoot looks like about 80-100%, and it's 
>real fast, so it might also be a probe compensation artifact.  Very much 
>shorter timescale, though, than the big overshoot mentioned above.  It 
>could also be a termination thing. When I look at the unfiltered data, the 
>overshoot is a lot bigger... 500%, making me think very capacitance 
>coupling the edge through.
>
>The final ringing is interesting too.. a much higher frequency (1 MHz?) 
>than the other stuff. Perhaps a parasitic in the gap circuit after it has 
>finally quenched.
.............