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why do SGTC and SSTC's have differant outputs than VTTC's

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LAN_403

teravolt

Sat Mar 18 2006, 05:41AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

In all of the pictures and videos I've seen the outputs of VTTC move out in straight lines vs. zigzag with regular TC's. If there was a VTTC big enough would the spark arc around and strike the ground? Does anybody think that a tesla of any type could generate sparks ina some what sraight line? and what is the bigest VTTC built as far as spark length? Maby the VTTC's have higher frequency components in them? What do you think

...

Sat Mar 18 2006, 05:54AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

I think that the reason that vttc/sstc have straighter sparks that sgt's is that in a vttc/sstc the related to the fact that a tc only gets one 'bang' every 1/50 of a second (when the sg fires) were as a vt/sstc are fed at their resonant frequency...

I believe the duel 811a coils get ~30" I have yet to see a vttc that needs a strike rail; even with streamer length longer than the secondary height. This is because so long as you put the breakout point on top the streamers never find their way down to the bottom of the coil.

As to making a strait line of streamers, my vttc is pretty dang strait (the Y one in my avitar was a very rare event), but it would be very hard to make one perfectally strait... You might be able to design a topload that creates an e-field that forces them to be strait, or use some huge magnets...

Plasmaniac

Sat Mar 18 2006, 09:22AM

Registered Member #206 Joined: Sat Feb 18 2006, 03:17PM
Location:
Posts: 72

IIRC, the sword-like streamers are the result of using only one halfwave. If you use halfwave reciftation for a SSTC, you can get nearly the same output.

HV Enthusiast

Sat Mar 18 2006, 01:32PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Plasmaniac wrote ...

IIRC, the sword-like streamers are the result of using only one halfwave. If you use halfwave reciftation for a SSTC, you can get nearly the same output.

Not really. The sword-like streamers have to my knowledge only been produced by vacuum tube coils. There has not been a definitive answer yet to why these swordlike streamers occur in VTTCs and they have NOT been duplicated in SSTCs yet. There was some work done a few years ago where some have tried to run an SSTC using the same RF envelope shape as seen in VTTCs, but from what i hear, the experiment wasn't successful.

So the simple word is, no one really understands why the swordlike streamers occur in VTTCs. Its still a mystery!

Steve Conner

Sat Mar 18 2006, 02:45PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Nobody "really" knows for sure. But we think sword streamers are caused by the combination of two things: A coil with a high resonant frequency (like over 500kHz) and a drive waveform with a fairly gentle rising envelope, such as a half-cycle of AC line. I have seen pictures of a small DRSSTC making sword streamers at 450kHz, with no energy storage capacitors and a staccato circuit instead of an interrupter. It was built by a Czech guy "Rayer" IIRC.

...

Sat Mar 18 2006, 04:07PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

I believe the swordlike streamers only show up in a certain frequency range even with vttc's My vttc (resonating at .8mhz on a half wave rectified mot) gives sstc-like streamers... And I remember someone saying that if they put a larger secondary on their vttc they loose the swordlike streamers...

vasil

Sat Mar 18 2006, 04:21PM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

Sometime, for 100-120 VDc input, half rectyfied, the Royer SSTC shows streamers that look like the VTTC output.

http://d.turboupload.com/d/439677/AVSEQ04.MPG.html

Of course the discharge is branched, but it is possible to obtain lesser streamers using a short and thicker nail.
I believe it depends by the input shape, power, frequency...How are they related, I dont know...

williamn

Sat Mar 25 2006, 02:14AM

Registered Member #55 Joined: Thu Feb 09 2006, 04:56AM
Location:
Posts: 149

I was able to get very sword like streamers with a CW PLL SSTC. This coil used halfwave rectified mains. Heres one of the few pictures I have, I mounted the breakout to the side for this particular one.

P1010135

[Edit: Fixed oversize picture]

Avalanche

Sat Mar 25 2006, 11:38AM

Registered Member #103 Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845

It definitely has something to do with the waveform going into the bridge. The long thin streamers are interesting though, and I think it has something to do with the varying voltage of each cycle. My theory is that the air is still ionised from the last cycle of the oscillator, so a higher voltage cycle means the streamer can form further away, therefore it grows longer instead of bushing out, like it does if you run in CW mode where each cycle has the same voltage. Therefore each half cycle forms one long sword.... not sure.

This is a picture I captured from one of my SSTCs, a single half cycle forming a sword. Interestingly it has a spiral around it too, very strange indeed. I would love to look into it further, by feeding different waveforms into the bridge. Maybe a signal generator hooked to an audio amp would do for a small power supply into the bridge....

1143286702 103 FT4698 Av Sstc3 Vttclike1

Finn Hammer

Sat Mar 25 2006, 05:44PM

Registered Member #205 Joined: Sat Feb 18 2006, 11:59AM
Location: SkÃ¸rping, Denmark
Posts: 741

Holy moly.

Here is something that I know.

On a DRSSTC, there is litle point in letting the on time exeed 150-200ÂµS. This gives branched streamers like the ones we get from disruptive TC`s.
However, with a SSTC, when the on time approaches 1mS the streamers change appearance from branched to straight with corkscrew base.
It should be easy enough to temporarily modify your pulser to verify this.
Cheers, Finn Hammer

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