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10 minute SSTC

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Goodchild

Wed Nov 28 2012, 03:28AM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

Hi Folks,

Just wanted to share a fast project. I needed a HV AC source to test out some of the fabulous plasma globes made by zrg. His work can be found here

I have not had an SSTC around for many years and the QCW is undergoing upgrades so I needed to throw together a fast SSTC to test out the new globes that came in the mail today.

My solution, a 10 min SSTC! I had all the parts on hand and mostly assembled so I just threw them together and made some sparks. The spark output is minimal but that's ok because all I was after was the E-field. The driver board is actually a UD DR driver (without phase lead) it surprisingly works very well as an SSTC drive go figure... It is running in base current feedback mode with a 33:1 CT. The power transistors are 30N60 ISOTOP IGBTs or something I had around collecting dust.

Here are some photos and a video, enjoy!

Video:

Physics Junkie

Wed Nov 28 2012, 04:55AM

Registered Member #7267 Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407

Very nice. I dont know anything about plazma globes but I wonder if something with a much larger e field like a larger dr might be able to light the globe without having to touch it with sparks much like other noble gases/fluorescent lights.

Goodchild

Wed Nov 28 2012, 05:13AM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

Well I have to get rather close because I'm only putting in about 30W of power. If I was to run it off of mains and put in maybe a couple hundred watts it would be another story.

Dr. Drone

Wed Nov 28 2012, 05:13AM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
Location:
Posts: 1673

Goodchild

Wed Nov 28 2012, 05:16AM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

That's what I was wondering, QCW or VTTC would be sweet to test it out on! We will have to crank out one of your VTTCs and give it go! Although I don't think I want to get my hand near Quadzilla... hehe

RickR

Wed Nov 28 2012, 06:20PM

Registered Member #93 Joined: Thu Feb 09 2006, 04:11PM
Location: Houston, Texas
Posts: 64

Zrg can probably tell you more about this, but I'm wondering if placing the globe in direct contact with the plasma might cause pinhole-sized punctures in the glass. Maybe the power's so low that it doesn't matter, but it's worth considering given what I imagine is the cost of each globe.

EDIT: I just viewed one of zrg's videos, and it looks like he's doing what I just cautioned about. So maybe I'm talking out of my hat. With more powerful coils, I still think it would be best to just use the E-field to start the discharge rather than expose the globe directly to the plasma.

-Rick

Goodchild

Wed Nov 28 2012, 06:50PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

I agree, this is why I didn't pull out one of my DRs rather I made this little 30W coil for testing. I will probably end up making a little class E thing to play with the plasma globes in the future.

Steve Conner

Wed Nov 28 2012, 09:01PM

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

I once destroyed a neon beer sign like that. I put it on top of a Tesla coil, and when I tried it again a couple of days later, it was completely non-functional. I assume the glass got punctured and the neon got away.

zrg

Wed Nov 28 2012, 11:20PM

Registered Member #4762 Joined: Sun May 06 2012, 05:59PM
Location: Russia
Posts: 93

With CW coils it is possible to touch the streamer directly with the glass of the plasma ball for a second. That usually doesn't do any damage to it. I usually do that to ignite the discharge easily. But longer exposure such as in Goodchild's video can be harmful. The streamer's plasma temperature is really high and the glass can easily get cracked from thermal expansion.
The best way is to quickly touch the topload with the ball, and then immediately remove it to the safe distance. As you know, the discharge in the low pressure gas is much harder to ignite than to sustain, and the E field is most powerful near the topload, so that'll keep the ball running and safe.

Any pulsed coils are very likely to destroy the balls with microcracks. I've had some of the bigger balls lying around while testing the big SGTC, which sometimes hit them to the glass, and several days later half of them were leaked, and there's absolutely no way to repair such a ball in home lab conditions. Pulse lengths shorter than a ~5 ms are really not recommended for direct strikes.

Goodchild

Thu Nov 29 2012, 06:21AM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

Good tip, I was trying to be sure it didn't heat up the globs too much when I did have direct contact. At most they got up to maybe 10 to 20 C above ambient. For some reason it's much harder to get the tubes to ignite off the toroid, may need a bigger toroid.

I'm starting to see why having an internal electrode is a good idea! I imagine it makes for much easier ignition.

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