Fusion Success with Precipitator Power Supply

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Bob Reite
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Re: Fusion Success with Precipitator Power Supply

Post by Bob Reite »

I asked my seller about the purpose of the 2 dip switches and the four pin header. He did not respond to my question about the header. As far as the switches all he said was "You can just ignore them for normal operation", so I left them as shown in the photo.

I did get a .docx instruction sheet from the seller. Grab a copy at: http://telcen.com/gbopix/CNC7353-600.docx

I came to pretty much the same conclusions as Rex Allers. I do find it interesting that the instructions specify "Positive and negative discharge distance should be less than 8cm" to protect from over voltage. Apparently arcing the output won't damage the supply, but letting the HV get too high will.

The voltage control is wired as a two terminal device, that will make it easer to remote it. I'll report back when I get it set up so I can safely adjust it hot and see if can get more current out of it at a higher voltage.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Mark Rowley
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Re: Fusion Success with Precipitator Power Supply

Post by Mark Rowley »

Hi Rex,
That’s some top-notch sleuthing! I’m looking forward to your results.

I have yet to test the 60 to any reportable degree due to some flashover issues with my 30kV feedthru. I’ll post more about that in a different thread.

Finn was fairly clear about his concern regarding a flashover between the core and output wire. Main reason I’m running my supplies under mineral oil. Not worth chancing the potential damage by running it in open air.

Bob, thanks for reaching out to the seller. It was on my list but hadn’t done it yet. Even though the instructions are anemic, the info about “locked state” is a good thing to know. Had no idea.

Mark Rowley
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Bob Reite
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Re: Fusion Success with Precipitator Power Supply

Post by Bob Reite »

Somehow I killed the driver circuit after extending the voltage control. It might have been because I had an open circuit.

In any case, I was planning to trash the factory drivers and build my own, but I decided to research the issue of driving these flybacks in parallel and connecting the outputs in series. I used my trusty bullet proof audio amps with the function generator to drive the primaries. Even though I was putting in only 70 V RMS, I was able to get 35 KV at 7 mA out of the things. I increased the load impedance (by lowering the chamber pressure) and got the arcing again at around 48 KV. I was able to determine that it was the highest potential transformer arcing to the core. Even though the core is on an insulated board, I suspect that it was also arcing from the core to the primary.

Bottom line, I don't think these will be usable for full fledged fusors, unless derated perhaps to 40 KV tops. In the intended application, the electrostatic precipitator, plus and minus are left floating so there is no stress from the HV winding to the core, certainly not as much as when one end of the output is grounded.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Mark Rowley
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Re: Fusion Success with Precipitator Power Supply

Post by Mark Rowley »

I disagree, at least at this point. Proof will be in the doing and I’ll be moving forward with the tests.

If I end up being wrong then so be it. But that being said, Ive yet to blow out either of my supplies.

And what is the definition of “full fledged”? A spherical large cavity fusor? I’ve logged close to a full hour of neutron production at 30kV with the smaller supply with no hiccups. I contend that after the feedthru mod is complete a similar result will follow with the 60.

You’re too quick on the naysayer button. Give it a chance.

Mark Rowley.
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Bob Reite
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Re: Fusion Success with Precipitator Power Supply

Post by Bob Reite »

As I said, if you derate the supply to 40 KV it should work fine as it stands. The small cross fusors seem to do quite well at 30 KV. I am going for higher Q in an 8 inch cylinder, and I want to get to 50 KV at 10 mA. The grid design I'm using now can handle 500 watts input. I dismantled my supply transformers and there is no evidence of damage from the arcing, which is good news. I plan to make some changes that should solve the arcing problem at higher voltages.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Mark Rowley
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Re: Fusion Success with Precipitator Power Supply

Post by Mark Rowley »

Eight inches is the Carlsbad Caverns compared to a 2.75" system. If your goal is maximum fusion potential, then yes, you'd want something better...even me. 10mA at 50kV would be a bit much for one. But with that being said, even larger systems like Richard's and Carl's generated respectable neutrons well within the operating limits of these power supplies.

A quick search revealed these examples (being a smattering of many):

"50 kV / 4 mA. A BF3 detector nearby was happily chirping away at this point"
viewtopic.php?f=18&t=7768&p=56184#p56180

"40kV at 5Ma"
viewtopic.php?f=6&t=2770&p=16689#p16689

"50.7 Kv (at supply) 3.8 ma average (fairly stable)"
viewtopic.php?f=53&t=370&hilit=neutron+club

"33,550V -- 5mA -- ~10 Microns -- 1000 CPM on 22" RS He3 tube 3' from Poissor"
viewtopic.php?f=18&t=7861&hilit=neutron+club

Regarding your arcing, I highly recommend you pot these supplies in oil before venturing past 20kV. I'm not sure why you pushed it to 48kV in open air.

Mark Rowley
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Bob Reite
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Re: Fusion Success with Precipitator Power Supply

Post by Bob Reite »

Just don't like having to deal with oil. My existing supply with the 8 stage CW multiplier works fine up to 50KV in air, but it will only do 5 mA at that voltage. Now I know that people are going to ask why I just don't stick with that supply or improve the drive to it. Reason is I'm working on a new design that needs two independent supplies, and I wanted to see what those precipitator supplies could do.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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