Re: More results from DRSSTC land

["Tesla list" <tesla@xxxxxxxxxx>]

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