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Re: More results from DRSSTC land



Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Steve,

At 04:42 PM 6/1/2005, you wrote:
Hi all,

I have had my DRSSTC together and working for a while now, and have made some interesting observations.

1) By hooking it to a digital scope I was able to measure the instantaneous power output from the H-bridge, and integrate it to get the bang energy.
http://www.scopeboy.com/tesla/drsstc/scope/analysis.gif

Nice!!! It seems like your lower rail voltage is very solid but your upper rail is very soft and is drooping a lot. There might be something wrong there with the rail power supplies like a bad +V cap...



It works out to over 5 Joules. Remember this system has a 4x13" toroid and 5.5x13" secondary coil, therefore it can hold maybe 1 to 1.5J before breakout. So this is evidence for the argument I was having with Antonio a while back ;)

This actual bang produced a 22" ground strike. It was operating on the upper pole at ~220kHz. There are some more detailed screen dumps where you can see exactly what the PLL driver is up to-

http://www.scopeboy.com/tesla/drsstc/scope/bangcapture36.jpg

Looks great! Nice triggering!

http://www.scopeboy.com/tesla/drsstc/scope/bangcapture36_zoomstart.jpg

The triggering falls behind some in the middle. This might be enough here to hurt the output.


http://www.scopeboy.com/tesla/drsstc/scope/bangcapture36_zoom_iddle.jpg
http://www.scopeboy.com/tesla/drsstc/scope/bangcapture36_zoom2.jpg

It was not too good at tracking the sudden shift in frequency due to the arc connecting with ground. I later found out that the tuning was set wrongly and it was hitting the lower frequency limit. It probably tracks better now, but I never got the chance to retest it.

The coil was demonstrated at Derby and managed a 33" arc to ground. I have some pictures that were taken by Adam Horden http://www.adamhorden.net/

http://photos.adamhorden.net/SCDRSSTC/DSCF3069
here is the actual 33" arc (partly blotted out by sunlight reflecting off the topload of another coil)


http://photos.adamhorden.net/albums/Derby_2005/SC_DRSSTC.wmv
a movie of the coil operating (wmv format, might not play on macs or linux?)

Nice!!! I see you can do ground arcs and even had a primary arc event without blowing anything up :-))



I was surprised that it "only" got 33". I tried several different tunings but the upper pole/tight coupling setup gave the best result of all. With this tuning it needed only ~180A peak to get that spark length, and flashover was what limited it. I tried currents up to 300A with the other tunings but couldn't beat that length.

No matter the tuning, the burst length didn't cause any more growth (only brightening and thickening) above ~150us and the streamers had reached more or less full length by a breakrate of 100Hz. I have some ideas about that lack of growth and will post them later.

Yep!!!

Cheers,

        Terry



Steve Conner