A new topology for building a low-cost DIY HV power supply ... 30kV/80W for $25.

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Richard Hull
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Re: A new topology for building a low-cost DIY HV power supp

Post by Richard Hull »

I will be very curious to see if any one using this topology ever enters the neutron club. This is a great idea and effort. All the best on this to any and all using it in a fusor. Slick thinking and design.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Benjamin Walsh
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Re: A new topology for building a low-cost DIY HV power supp

Post by Benjamin Walsh »

Chris, I was wondering if you might be willing to part with a few of your inverters (for a price, of course)? It would be greatly appreciated.

Thanks for the great information and idea regardless of your decision.
-Ben


(Sorry to make a public post, but I lurk too much and don't post enough to have private messaging enabled. Oops.)
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Chris Bradley
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Re: A new topology for building a low-cost DIY HV power supp

Post by Chris Bradley »

They are boxed up at the moment but in principle I could do that (if I can find them!!). What is the specification/project you are aiming for and how many do you want, where are you?

These days, it might be easier to find a smaller number of higher power lighting or OBIT transformers that are also useful in this arrangement, as they can make use of the 'GFI' type devices.
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Re: A new topology for building a low-cost DIY HV power supp

Post by Benjamin Walsh »

I was hoping to achieve 30kv at around 15 mA. I was looking at purchasing about 25-30 of your inverters. I live in Southern California (if you want to pm me your email, I can send you my address) about 30 minutes outside Los Angeles.
I hadn't considered an OBIT or similar transformer, and a cursory glance shows that it might end up being a tad more expensive than a CCFL based transformer, depending on how much you are willing to part with your inverters for. But a great option nonetheless!

Thanks,
Ben
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Re: A new topology for building a low-cost DIY HV power supp

Post by James Hammond »

Chris, how exactly did you go about powering the CCFL inverters you had?
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Richard Hull
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Re: A new topology for building a low-cost DIY HV power supp

Post by Richard Hull »

I build GM counters for sale at hamfests and use only CCFL inverters to obtain the HV. They typically take 5-12 volts DC, depending on the inverter and demand from 20ma to over 250ma of current at these voltages, again, depending on the inverter. Powering 1 to 50 inverters is a snap as construction of a low voltage, high current supply is child's play.

As my inverters need only 700 volts HV and only 100 microamps or so of current, the inverters I use run off 5 volts DC. They draw about 25ma from the 9 volt transistor battery I use in the GM counter. I use a LDO 5 volt regulator to power the inverter from the 9 volt battery. (Lets the battery voltage drop pretty low before it needs replacement.)

I also have some very small Toshiba inverters that can supply 1.3kv @ 3ma. These run off 12 volts and drag 370ma from the supply!

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Benjamin Walsh
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Re: A new topology for building a low-cost DIY HV power supp

Post by Benjamin Walsh »

I'm just going to leave this here.... You can get 5 (absolutely 100% positively free. With pretty fast shipping too!) samples for 8 different inverters.

http://www.coilcraft.com/ccfl.cfm
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Re: A new topology for building a low-cost DIY HV power supp

Post by Dave Xanatos »

Benjamin Walsh wrote:I'm just going to leave this here.... You can get 5 (absolutely 100% positively free. With pretty fast shipping too!) samples for 8 different inverters.

http://www.coilcraft.com/ccfl.cfm

Cute little transformers, but how would you ever get enough of them to generate the CURRENT you need in a fusor? You'd need like a hundred of these :)
It would take decades of work, by thousands of scientists, in a particle accelerator powered by dump trucks of flaming grant money! - Professor Farnsworth/FUTURAMA
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Re: A new topology for building a low-cost DIY HV power supp

Post by Benjamin Walsh »

Seeing as this ( https://web.archive.org/web/20121018042 ... -40mm.html ) is what Chris used, I think that somewhat less than 100 might work.... 2 of the inverters (for 10 free samples between the two) are rated higher than Chris's, so hopefully they can be run at higher voltage/current like Chris did to his. He ended up using 6 inverters to make a 30kv 60 watt transformer. And even if these end up not living up to quite what his were, there are still extras that can be thrown into the circuit to boost the current. And it'll cost you pretty much nothing. For freebies I'm not going to complain too much.
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Re: A new topology for building a low-cost DIY HV power supp

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The hottest transformer I saw was 2kv @11ma that means 15 would make 30 kv in series with zero current reserve. (The foregoing would demand a primary drive of about 400 watts of high frequency energy assuming about 80% conversion efficiency!) That 80 watts is long gone and exceeded.

I would wonder how well the secondaries might connect in parallel? This would be demanded to give more useful current.
Isolation on the primary driver systems might become an issue especially if driven in parallel. Lots to work out here, but maybe worth it. Good luck to all who venture out here in an attempt to get real, viable fusion voltage and current in fusion load and operational conditions.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Benjamin Walsh
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Re: A new topology for building a low-cost DIY HV power supp

Post by Benjamin Walsh »

Thankfully I am not the only one working on this fusor effort. As such I more than enough of the highest rated inverters. I feel really bad for having so many free samples, I guess I'll just have to make it up to them by buying some stuff in the future from them :). But I digress.

I did some math on the inverters. I calculated assuming 1.6kv output at 11mA. I figured that I will need 60ish inverters for the voltages and current I'm looking to have as a maximum output, just to have some wiggle room with inefficiency and drop in output. And thats with quite a bit of extra current and voltage available, in case I want to operate at some higher levels later on in my efforts. (Not any time remotely soon.) And if it works less well than hoped, I should still have enough juice to power a fusor by powering those extra inverters rather than leaving them off and just sitting there. But if this works as well as I'm hoping it will , I don't want to have to worry about modifying it in the future to achieve higher voltage. I'm probably going to make an Image du Jour post documenting my fusor sometime soon, so look for updates on my efforts there.
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Richard Hull
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Re: A new topology for building a low-cost DIY HV power supp

Post by Richard Hull »

Defintiely! Keep us informed on your efforts.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: A new topology for building a low-cost DIY HV power supp

Post by prestonbarrows »

For what it is worth, I have seen similar topologies used successfully up to hundreds of kV and tens of kW. Basically consists of a dozen or so Glassman style power supplies around 20-50kV apiece each floating the ground of the next. The mains line power is fed up with a spinning shaft and a generator set at each stage. You can keep on stacking them up until limited by corona/arcing at the top end or the power rating of your motor-generator set.
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Re: A new topology for building a low-cost DIY HV power supp

Post by Chris Bradley »

I'm pleased to see that there is an interest in building the first supply with this topology to power a conventional fusor. It will be interesting to get some learning from that.

In regards evaluating how many inverters you would need for a given power, I think in general you will need to push smaller inverters towards their limit to get the best solution. These things are commercial and are designed with so much head-room that both continual use (possibly in 'thermally compromised' circumstances) and the vagaries of manufacturing tolerances should not compromise their tolerance to withstand a long life. If you blow up a few of the lower performing ones, just replace them til they stop failing!

In the case of the inverters I was using, I tested at 15W, which was over 3 times their rating, for a half an hour at a time and did not have any failures because of the power demand I was making on them. At 20W I started to get one or two failures, hence I pitched the title power at just under 6 x 15W as I knew they were reliable there. But it is all an experiment with any other inverters you can find. Maybe you will find better ones still and push them even harder!?

I did take a quick look and I came across these. I asked the vendors but they do not know the rated power. The fact that they can take anything from 5 to 28V would make them more attractive to me now than the inverters I got, which are really 12V but can be pushed to just under 20V reliably. At 28V design limit, that could mean some very useful '+' power, maybe. Dunno 'til you try.

http://www.ebay.co.uk/itm/310952320305
http://www.ebay.co.uk/itm/201075984427

I reckon I could get more out of those than I do out of the ones I have used. They actually look quite good quality, mine were pretty cheap manufacture.

In regards getting serious power, I would tend to advocate looking for a set of lighting transformers in the 60W range. Don't forget that you can still use one power supply to feed a number of stages, it doesn't have to be one supply per stage. So maybe you get 5 60W lighting inverters and use each to power 3 stages each, of 15 total, that way you'd get 300W output at 30 x rated voltage output of the inverters.
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Re: A new topology for building a low-cost DIY HV power supp

Post by nicolas leboucher »

hello chris,

after a long time of heavy workload, I m back to go on my projects and one of these is still to reproduce your epicyclotron experiment.
I ve found a suitable "multipurpose" vacuum chamber, completed my vacuum system and now I ve to build my négative HV PSU for the outer electrodes. I ‘m also on the way to complete a new website.

I ve got a few more questions:

- which value for the impedance of the small inverters do you take into account to choose the resistors that are connected between the capacitors and the diodes network ?

- can you give more details on the circuit that you build to switch the negative HV between the four electrodes ?How do you implement the 8 NOR gates circuit, with which components? MOSFETS as you said in your patent ? Do you have any picture or diagram of your circuit ?

I m on the way to test a first HV PSU with two inverters, more to come

nicolas
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