Building a Fusor at 12 Years Old

For posts specifically relating to fusor design, construction, and operation.
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Scott Moroch
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Re: Building a Fusor at 12 Years Old

Post by Scott Moroch » Sat Aug 03, 2013 2:57 am

I have purchased a robinair pump amd the same high voltage power supply from united nuclear. I quickly tested my fusor and it failed. I have spent a month researching my equipment and know a lot about it. If you need any assistance with your demo fusor feel free to ask me any questions especially about the high voltage or pump. I have been told that 25kv@5ma will not work I will tell you how it goes. I will be testing my fusor again shortly.

Good luck,

Scott
"In the middle of difficulty lies opportunity"
-Albert Einstein

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Carl Willis
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Re: Building a Fusor at 12 Years Old

Post by Carl Willis » Sat Aug 03, 2013 5:23 am

Jack,

Can you clarify your comment about the failure? I'm not clear from reading if you mean the experiment with the fusor failed, somehow, or if the power supply failed (broke down).

The power supply in question is not one that meets the frequently-discussed criteria for even "demo" fusors, as its maximum output will be less than 12 watts. In other words, it cannot deliver more than 480 microamps at 25 kV, and in reality probably delivers considerably less. The reason why is simple: it is powered from a 12V/1A power supply (12 watts max input). If one is lucky, a faint glow discharge might be sustained in a fusor with this supply. However, it's not evident that the supply can even be hooked up to a typical fusor geometry with the anode (chamber or outer electrode) grounded and still deliver output. Maybe it can, maybe not; all depends on the internal configuration, not described by United Nuclear. Anyway, you did the experiment and hopefully can shed light on what exactly didn't work out for you and why.

The forum's archives document a wealth of proven power supply solutions, including neon sign transformers (for "demo" fusors only), x-ray transformers, microwave oven transformers driving large Cockroft-Walton multipliers, homebrew off-line inverters driving RF transformers and multipliers, multipliers driven by multiple CCFL inverters, and of course traditional HV power supplies made by Spellman, Glassman, Bertan, Universal Voltronics, Hipotronics, etc. obtained as surplus. Suitable power supplies need not be expensive. Previous experience or basic knowledge of electronics is a strongly-advised prerequisite to a fusor project.

-Carl
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Scott Moroch
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Re: Building a Fusor at 12 Years Old

Post by Scott Moroch » Sat Aug 03, 2013 5:44 pm

Carl,

If this high voltage power supply from united nuclear did in fact produce 25kv@5ma and no less than 5ma. Could this power supply work in a demo fusor. I have spent hours going through the posts on this website and have seen people who say they have run a demo fusor at 8kv@4ma.

Sincerely,

Scott
"In the middle of difficulty lies opportunity"
-Albert Einstein

Tom McCarthy
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Re: Building a Fusor at 12 Years Old

Post by Tom McCarthy » Sat Aug 03, 2013 5:50 pm

Scott,

Your q's directed to Carl, hope ya don't mind me trying to answer.

From what I've read a 5ma 10kv supply can run a demo fusor - I haven't built one or anything though...
I'm not sure about the current, 10kv seems to be enough for a demo but as I said I'm not too sure about the current needed for a demo Fusor.

Hope it helped,
Tom

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Scott Moroch
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Re: Building a Fusor at 12 Years Old

Post by Scott Moroch » Sat Aug 03, 2013 5:59 pm

Tom,

Thank you for your help. I emailed the company and they told me they test every high voltage supply to make sure it runs at 25kv@5ma and if it does not, then I can ship it back and they will fix it to run at that. So my main concern was making sure that it will run at 5ma. I saw one post where someone produced neutrons at 30kv@7ma. Thank you again for your help.

Sincerely,

Scott
"In the middle of difficulty lies opportunity"
-Albert Einstein

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Nick Peskosky
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Re: Building a Fusor at 12 Years Old

Post by Nick Peskosky » Sun Aug 04, 2013 12:07 am

Scott,

Carl attempted to clarify this in his post earlier but let me make this explicit beyond a doubt. Consider Ohm's law: If the United Nuclear supply is driven by a 12VDC adapter rated at a MAXIMUM current of 1A then under ideal circumstances assuming no switching or joule heating losses the supply could source an input power of P = I*R = (1A)*(12V) = 12 Watts. UN quoted you that the supply could run at 25kV and 5mA, referring back to our power equation that would mean P = I*V = (25,000V)*(0.005A) = 125 Watts... leaving 113 Watts of electrical power evolving out of thin air. The person you spoke to may have meant that the supply might be able to deliver 25kV OR 5mA current over it's range of operation but based on the aforementioned math it's not going to occur simultaneously. I've purchased chemicals and lab glassware from UN before and have been less than thrilled with their customer support.

Sorry to rain on the parade.

Nick
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"The whole of science is nothing more than the refinement of everyday thinking." - Albert Einstein

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Carl Willis
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Re: Building a Fusor at 12 Years Old

Post by Carl Willis » Sun Aug 04, 2013 12:17 am

Scott,

Their own description makes clear, in two places, that the power supply CANNOT source 5 mA at the same time it is delivering 25 kV.

First of all, it is driven with a 12V / 1A power supply. Multiply twelve by one. That's how much power is available to the HV supply. Conservation of energy dictates that more power cannot come out of the HVPS than goes into the HVPS. So 12 watts can be delivered, in theory (arbitrarily somewhat less in practice). If delivery voltage is fixed at 25 kV, you find the maximum current theoretically available at that voltage by dividing 12 by 25,000. It's nowhere close to 5 mA. It's physically impossible for it to deliver 5 mA at 25 kV.

Secondly, I quote from UN's website:
The HV Power Supply produces 25 kV (open circuit) with a short circuit current of <5 ma.
25 kV OPEN CIRCUIT. Translation: the load draws NO current. Short circuit current of <5 mA means it produces less than 5 mA at short circuit, or zero volts output.

Do the math.

Do the reading.


-Carl
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TEL: +1-505-412-3277

charlie_mccartney
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Re: Building a Fusor at 12 Years Old

Post by charlie_mccartney » Sun Aug 04, 2013 3:18 am

I am 15 and I have aqquired a decent amount of parts and just a word of knowledge, get a REAL NST for free-$90. It needs to be solid metal and weigh 20-50 pounds (mine weighed at 45). It also needs to have ceramic knobs for the input and outputs. My NST is 15kv 30ma.

He has one more if you would like to buy it.
Here is his Ebay http://myworld.ebay.com/markebenson/
Charlie McCartney
charlie.mccartney1104@gmail.com
charliespersonalproject.weebly.com

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Scott Moroch
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Re: Building a Fusor at 12 Years Old

Post by Scott Moroch » Sun Aug 04, 2013 3:24 am

Thank you everyone for your help with my high voltage power supply. Luckily I can still use the United Nuclear power supply for other science experiments and I will probably buy a neon sign transformer and use that for my fusor.

Thanks again,

Scott
"In the middle of difficulty lies opportunity"
-Albert Einstein

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