Re: scopes and measurements

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

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