What kind of power supply do I need?

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Crockett Hensley
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Real name: Crockett Hensley

What kind of power supply do I need?

Post by Crockett Hensley » Fri Sep 07, 2018 6:49 pm

Hello Fusioneers,

I am fairly new to nuclear fusion and I am attempting to construct a demo fusor. I have a vacuum pump, and I can easily get the necessary vacuum chamber equipment. However, what I am wondering about is how to get the HV power supply for my demo fusor. I know that for a real fusor I would need a high quality power supply, but for my demo fusor can I just use a flyback converter salvaged from a microwave or a CRT tv? Or, better yet, would it be possible to use an ordinary wall transformer (designed for stepping down 120v to 5v) in reverse, connecting the wall voltage to the secondary coil and the fusor to the primary coil (obviously through a current rectifier and in parallel with a capacitor) to turn the 120v into 2880v. I think this would work in theory, but I'm a bit concerned since I've never heard of anyone doing it and it seems like if getting such a power supply were so easy then everyone would do it. Also I'm afraid that the transformer might burn up in such a configuration. I'm just looking for a little guidance on that account. Would the wall transformer in reverse work? Would another kind of easy to get transformer work? Or do I need to seek out a serious power supply?

Thanks in advance,

Crockett Hensley

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Dennis P Brown
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Re: What kind of power supply do I need?

Post by Dennis P Brown » Fri Sep 07, 2018 7:08 pm

Reversing a step down transformer has issues - the wiring insulation is no where near rated for such high voltage. There are methods to address this but with a neon sign transformer (NST) being fairly cheap, and fairly safe, a NST would for a new person tend to make a better project (but, of course, useless for real fusion.)

As for a fusor grade supply (with BOTH enough voltage AND current AND correct polarity is essential), watching ebay and looking for deals is your best bet; however, working units that are fairly turn key can be a bit expensive.

A simple high voltage and sufficient power transformer can be the lowest price to obtain for fusion work. Then there is the issue that one must build/install the rest of the power supply supporting systems - variac, diodes, ballast resistor, install display meters, and proper cable hookup. Not something someone with no experience should undertake lightly - a reason a NST system offers good training in doing many of these mini-projects as one gains experience and knowledge. Also, with a much safer and far more forgiving transformer (a typical NST can have its two terminals shorted together with no immediate harm. Don't ever try that with any other high voltage transformer.)

Going high frequency and using voltage multipliers is strictly for a pro who has a good bit of electronics knowledge.

Finally, while a proper power supply is essential, one must also have deuterium gas and a proper detector system (for neutrons - that is a very special detector.) Including these in your plans is important, if you desire to do real fusion.

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Real name: Eduardo Machado
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Re: What kind of power supply do I need?

Post by Eduardo_Machado » Mon Sep 10, 2018 11:29 am


I just finished my demo fusor and I used a 12kV Neon HV transformer. It worked really fine.



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