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loneoceans

Mon Sept 29 2014, 05:50AM

Registered Member #4098 Joined: Fri Sept 16 2011, 09:26PM
Location:
Posts: 236

Hi everyone,

I guess I'm somewhat late to the QCW party, but I thought I'd share a simple and small QCW I finally got around to putting together after occasional on-and-off work. I started putting it together a year ago or so but never got around to finishing it until now. It's still very much a work in progress but I think I've figured out most of it. Here's it so far running at 150V, only half of the 300V I plan to run it at!

Update: Write-up in progress here -

I wanted to build a really simple QCW coil. It runs on a simple asynchronous buck converter via bang-bang control modulation, and I managed to put all the control circuitry on a nice small PCB. The QCW secondary itself is a 3.5 x 5.5" coil with a small spun toroid, and runs on a TO247 IGBT double-bridge which I made another compact PCB for.

15289405402 A0b9abf21d Z

The coil is driven by my version of the UD2 which I've called the UD2.7 (check it out here:

with primary feedback, and my buck converter I managed to get working.

UD27A SCHEMA Sept2014 Small

I've also posted my schematics and board layouts on my website. Hopefully this might be useful. Note that they are still experimental and I already have several ideas to improve it.

I haven't got around to tuning it or anything so these are really 'first light' photos. Right now it's running with a 150V ramp about 6 to 7ms long, with a fairly high operating frequency of 470 to 430kHz (winding mistake on my part), but it's pumping out about 100cm (~40 inch) sparks at just above 100A primary current. Each spark consumes about 31J of energy. Next up is a bit more fine tuning and I'll be able to push much more spark when I get it up to 300V :D (recently got a 240V transformer for this). Many thanks to Steve whose conversations really helped.

There isn't much documentation on QCWs so I'll be writing a fairly comprehensive page with all my schematics and designs as well as what I've learned building this coil. Feel free to ask questions.

Short Video of the coil running at 1pps:

(Some sparks look smaller/disappear because of the camera sensor read-out speed)

15387725142 B7118fe21b C

First light of QCW 1.

15201480729 2f290fdbb9 C

Here's a photo of my bridge. Everything stays basically cold. I like how colorful it came out. I've named it EasyBridge because it's so easy to mount IGBTs on by just soldering the pads directly. This makes replacing IGBTs really easy.

14861807825 D588bdb2e3 C

Here's my buck converter controller v1.0 (actually second version)
More to come soon!

kilovolt

Mon Sept 29 2014, 09:40AM

Registered Member #2018 Joined: Tue Mar 10 2009, 09:56AM
Location: Switzerland
Posts: 74

Loneoceans, that's an awesome project, I love it!!! Nice looking coil and great results. Thanks for posting.

Best regards
kilovolt

Graham Armitage

Mon Sept 29 2014, 11:54AM

Registered Member #6038 Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248

This is impressive. Never tried a QCW coil, but this is inspiring me. Thanks for sharing. You do some awesome work - neat construction. As always your photos are incredible too. Any video of it in operation?

teravolt

Mon Sept 29 2014, 04:55PM

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

Hi loneoceans, the pictures Are not showing up on your thread can you try again. I am building QCW to and I am always looking for ideas. thanks

Sigurthr

Mon Sept 29 2014, 05:23PM

Registered Member #4463 Joined: Wed Apr 18 2012, 08:08AM
Location: MI's Upper Peninsula
Posts: 597

Absolutely beautiful project and results. I haven't tried QCW yet myself either, but this looks extremely enticing, especially running on TO-247's!

Dr. Dark Current

Mon Sept 29 2014, 06:20PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Nice work, thumbs up

...

Mon Sept 29 2014, 06:35PM

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

Mighty impressive!

BSVi

Mon Sept 29 2014, 07:41PM

Registered Member #1637 Joined: Sat Aug 16 2008, 04:47AM
Location: Kiev, Ukraine
Posts: 83

I suppose this coil can give longer streamers. Looking forward to see how it operates at max bus voltage.

Dr. Dark Current

Mon Sept 29 2014, 11:26PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

loneoceans wrote ...

Feel free to ask questions.

So are you running on the upper or lower pole?

Mads Barnkob

Tue Sept 30 2014, 08:02AM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

Good results. While you think you are late for the QCW party, you are wrong, it would rather seem that you is the first to do a full documentation on your work and from the look of your boards you also have a simpler setup than the first experimental and developing versions we saw from other members :)

Could you please post some more photos of the rest of the setup, like the buck converter bridge, primary coil and capacitor etc

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