Re: Terry's DRSSTC - Experiment - A curious thing...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Steve,

At 10:04 PM 4/12/2005, you wrote:
> .....
> >
> > The 1, 2, 3... pulse thing did not seem too interesting.  After about 5 to
> > 10 pulse the streamers seem to reach a maximum level.  After that they just
> > last longer but their length does not increase....
>
> This has been found to be true not only when running the coil in
> "burst" mode (several pulses per firing with a long rest inbetween)
> but also true of increasing the length of each burst in themselves.
> The plasma just gets fatter, not longer.

Yeap!  Does not seem to be anything too exiting there...  Streamer growth 
per pulse seems to be pretty much as everyone imagines it to be.

> ......
> > Those are not really the exact numbers, but just increasing the BPS say
> > from 660 to 690 increased the length of the streamers about 5X!!
>
> I did notice that at very low powers, the growth was much more
> exaggerated.  My coil will go from spitting corona to forming nice
> streamers (probably 4X as long as the corona) when you really stomp on
> the BPS!

Yes!  that is what I was seeing!  Did you note any effects at other power 
levels?  Perhaps the effect is not a big deal at high power?


>  Then
> > increasing the BPS further to 720 made the streamers fall back to the short
> > discharge again!
>
> Very strange!

I was thinking I was hitting the AC buss cap charging cycle.  However, the 
computer controller and the AC line are not synchronized in any way....  I 
will have to get the scope and stuff on it...  But I sure don't see where 
the electronics would cause it.

> .....
>
> >
> > I don't "think" it is anything in the electronics.  There is nothing to
> > really cause it on the controller side.  I just used 20 pulses all the time
> > at fixed pulse width (35mS)
>
> Do you mean 35uS?  Or is this width the time between each group of firings?

I meant 35uS ;-)


>  so the total power is pretty much the
> > same.
>
> Well... the ENERGY is the same, but you are delivering it in a shorter
> amount of time, so power is greater at higher bps.  Or have i got
> something wrong?

Your right.


> >
> > I was wondering if the L and C of the streamer was resonating or
> > something.  But I could not imagine how that could be...  It certainly did
> > seem like the long streamers "go in and out of tune"....  You could adjust
> > the BPS to maximize the length....
>
> Hehe, gotta watch the IGBT heating then!

I have IGBT overtemp sensors :-)))

> My coil made some wild
> noises when running like this.  I could even tune my 2 oscillators to
> play musical 5ths, 3rds, octaves etc... it really WAS singing ;-).

At 1000 BPS, the thing really grates on the nerves!!  If I only have 35uS 
of pulse width, I suppose I could run at 10,000 BPS if the controller will 
think that fast. ;-)  By pulsing these high BPS bursts, we can still keep 
the overall duty cycle and power levels in the happy zone.


> Perhaps my next project should be to take an old junker PC and make it
> into a DRSSTC controller!

Yeah!!  You could probably make it talk and play music and such.  The 
computer could calculate power, current, IGBT heating and stuff too 
;-))  There are limitless possibilities there!!  You could hook it to the 
net so the TC has it's own IP address :o))  Set up a webcam and it could be 
run off the Internet by anyone with a "credit card" :o)))

I was thinking it would be the first coil on the net.  However, Paul and 
my's resonator experiment was all on the net a few years back (but that was 
not quite a real net controlled TC)...  However, a remote controlled TC on 
the net would be pretty cool and the DRSSTC does not wear out...


> > So curious if anyone has ever noticed streamer length dramatically coming
> > and going buy changing BPS a little at the above 600BPS level?
>
> I havent gone above 600bps.  Like i said, at low power the differences
> were dramatic, but i didnt get too much gain in spark length when it
> was maxed out on buss voltage.

Ok,  Maybe it is a subtle thing where the sparks go from a random brush to 
a streamer so at higher power it is a don't care.  But when you can fiddle 
with it in fine detail, it is a darn strange effect!

> This *might* change at more than
> 600bps so cant verify it.  My buss caps often sagged from this kind of
> use and would result in shorter sparks.  This is where it really
> helped to "gate" the interrupter to just send out 10 shots at a time
> or something.

I should not be sagging anything much.  But nothing is synced so it is not 
from an AC buss charging timing effect....


> Writing this email i see we should really start defining terms like
> "burst" "firing" "shot" etc... i think that *you* will know what i
> mean, but other people probably wont.  Care to make a set of
> definitions or should i?

You can ;-)  I would probably make silly things up :o))  I am still 
"unforgiven" for the OLTC :-))

Cheers,

        Terry



> Steve
>
> >
> > Cheers,
> >
> >         Terry
> >
> >