Re: scopes and measurements

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

Original poster: "Steven Ward by way of Terry Fritz <teslalist-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>

Hi Antonio,

The pic of your waveform, is not as clear as mine.  I have played with the 
adjustments, and i have managed to clear things up a bit.  I posted that as 
well, but it didnt make it:(.  I tried changing the coupling on my miniTC.
At 1" below the primary, i had 3rd notch, at .5" above, it would swing 
between 1st and second notch, then at 1" above, it was a constant 1st 
notch!  This of course was with a VERY small gap setting, so i didnt want 
to coil killing me with ozone as i play with the scope:).  I was really 
surprised to that the lower coupling as it seems was transferring energy 
faster.  Why does this happen?  I didnt note any better performance with 
the various couplings that i tried, though the scope did;).  Not sure what 
to make of it, maybe i can beat my 13" mark with the 4kv 38ma NST :)

Steve Ward.






>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: scopes and measurements
>Date: Tue, 14 Jan 2003 07:28:55 -0700
>
>Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
>
>Tesla list wrote:
>
>(Sending again, as it appears that the post was lost)
>
> > Original poster: "Steven Ward by way of Terry Fritz 
> <teslalist-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>
>
> > Sorry to be behind the times, but i just got a scope on ebay and was
> > looking at some VTTC and spark gap TC waveforms.  I just had a 12" length
> > of wire attached to the probe (10X).  I COULDNT BELIEVE IT!  You could
> > clearly see the 60hz envelope with the VTTC, and you could see a nearly
> > perfect sine wave inside of the envelope.  The waves looked much like a
> > sine, but the peaks were pointed a bit more, and there was a green glow
> > inbetween the parabolas themselves.  Im not sure what to make of that,
> > perhaps interference?  It looked like someone shaded in the region between
> > the X-axis and the wave itself, if this helps convey my idea.
>
>While the primary gap is conducting, you see a high-frequency burst at
>each zero crossing of the primary current. The bursts disappear when the
>gap ceases to conduct. Streamers can produce bursts too.
>
> > Then i
> > walked near the coil, and wow!  the frequency changed right before my eyes!
> > Putting my hand in front of the probe would distort the waves and make them
> > look wobbly.  As if i wasnt amazed by that, i took a peak at what the mini
> > coil looked like.  On a small gap setting with out breakout, it looked like
> > a large hump then a second smaller hump that slowly decayed across the
> > screen.  Is this "second notch" quenching?
>
>Yes.
>
> > Then i opened the gap a bit.
> > Now there was a bigger hump, then a medium, then a smaller one that
> > decayed.  Would this be 3rd notch (this is basically why im writing all of
> > this).
>
>Yes too.
>
> > I never understood this 'notch' thing when it came to quenching,
> > but i think im starting to see it:)  Ok, but inside these humps, it was a
> > bit confusing.  IT looked like at least one or 2 large sine waves with a
> > very small wave in the middle, and then another medium wave(though it did
> > often bounce between the first and the second scenarios i described).
>The
> > 2 large waves made humps noticeable, but the meduim and small wave were
> > almost continuously decaying (looked linear) the entire time(exept where
> > the humps ended inbetween one another).  Im wondering if pehaps each of
> > these waves i saw was representing something?  Is it possible that my probe
> > was picking up a current reading as well?  I though that the current rose
> > as the voltage fell toward the end of each bang?  I did not see this.
>So i
> > guess i was not picking up current.  But i cant help but wonder why i saw
> > so many different waves in there!
>
>Try to adjust the trigger and the time scale so you see just a single
>energy transfer cycle ("bang").
>The oscilloscope is probably overlapping "bangs" starting from the
>beginning with others caught in the middle of the proccess.
>Even so you will probably see a composition of positive and negative
>"bangs", with positive and negative similar signals overlapping.
>A not very good picture taken with an antenna, from my
>transformerless magnifier operating at full power, showing first
>notch quenching (It always quenches in this way) and energy transfer
>in 2.5 cycles.
>http://www.coe.ufrj.br/~acmq/tesla/567pwr1.jpg
>
>Antonio Carlos M. de Queiroz


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