HV power supply ideas

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GreenApple
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HV power supply ideas

Post by GreenApple »

Hi

For a while now ive decided myself to start building a small fusor (maybe powerful enough to fuse but im not sure if thats too dangerous) and after watching a lot of videos, artciles and documenting myself on the subject i have a pretty good general idea on how im going to do this. On most of the things ive read or watched people used neon sign tranfsormers sometimes coupled with a voltage multiplier or big power supplies that are way to dangerous for me.So im asking myself this question :what is the safest HV transformer i could use for my project ?
It doesn't really need to be powerful enough to fuse for now (but it could be nice). I don't have much experience with HV and im kind of scared when it comes to this subject so im always very careful.

Im new to the forum so tell me if i did anything wrong (my username maybe) and excuse me if you see some spelling mistakes, im from France.

Sincerely,
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Rich Feldman
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Re: HV power supply ideas

Post by Rich Feldman »

Welcome to the forum.

It's my turn to say: When you registered, you saw the rules. One says to use your real name. (I bet your father's name isn't APPLE.) Another says you should begin with a post to subforum called Please Introduce Yourself.

A neon sign is nothing to be afraid of. It has plenty of voltage and current to light up a demo fusor, and can't be damaged by an accidental short circuit. Then, by observing the plasma shapes, you can estimate the performance of your vacuum pumping system without using a vacuum gauge. Any HV power supply that can light up the demo plasma can give you a painful electric shock. Electricity from the wall can kill you even with no transformer to increase the voltage.
Last edited by Rich Feldman on Thu Apr 07, 2022 7:16 pm, edited 2 times in total.
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Liam David
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Re: HV power supply ideas

Post by Liam David »

There is no safe fusion-capable power supply. Neon sign transformers and MOTS (demo fusors only), and switching supplies, even the ones incapable of fusion, can all kill you. If you deem yourself unable to safely handle high voltages and are scared, then do not attempt to build a fusor. You should start with smaller, low-voltage electronics projects and work up from there. A DIY Geiger counter would be a great fusion-applicable and relatively safe project. Such an approach will serve you well in the long run

Welcome to the forum.
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Richard Hull
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Re: HV power supply ideas

Post by Richard Hull »

I will echo Liam's words. The one deadly aspect of doing real fusion here is electrical. By comparison radiation from an operating fusor is a virtual non-issue. One misstep at 30,000 ( where fusion is easily detected), and you are dead. Most of the older fusioneers here never work at those lower 25,000 to 30,000 volt levels where beginner work. We tend to exceed 40,000 volts up to nearly 80,000 volts. To work with voltages at these levels you need a good deal of HV experience.

Tesla coil builders learn about high voltage issues as part of their craft. However, only those who have built systems that can throw 6-8 foot arcs have been forced to deal with instantly deadly voltages found in the needed transformers to create such systems.

I might venture to say there is no great danger in making a fusor and in doing and proving fusion, save for the deadly power supply issues associated with powering the successful fusor.

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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Dennis P Brown
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Re: HV power supply ideas

Post by Dennis P Brown »

Neon-sign transformers (NST's) are safe and a great way to begin learning high voltage operation procedures - they will provide a nasty shock but aren't deadly if a mistake is made - they are current limited (the cores quickly saturate under any load) and their voltage drops to very low values when also under load. Adding a voltage multiplier (VM) to a NST will never get you fusion so such a power supply is problematic - the issue is that depending on the storage caps used such a supply can become very dangerous to very deadly. Building supplies that use VM's are a step above most people's electronic knowledge and require a great deal of effort and have a learning curve. However, a number of people here have done it here and posted their results (one very recently.) Worth reading.

Building and operating a real fusor requires skill and great deal of learning in order to be fairly safe (read the FAQ's here and some fusor build threads for certain.) The sources you site are really not very useful to get anyone 'ready' to build and operate a real fusor. One gains such experience by 'hand's on work' not by watch in vid's or reading other's posts that often offer no supporting proof that they have done fusion (we have strict rules on that aspect of claiming fusion here.) As Richard and Liam have pointed out - the power supply for a real fusor is absolutely deadly and permits zero mistakes.
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Rich Feldman
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Re: HV power supply ideas

Post by Rich Feldman »

Just got back from the flea market, where I sold a NST (nominal 7500 V, 20 mA) for $5 or $7 to a teenager accompanied by his parents.
Open circuit voltage is enough to reliably jump outside of the wires, if set up with a narrow gap.
They were talking about making a Jacob's Ladder to start with.

As Dennis pointed out, if there are no energy storage capacitors then the current won't exceed the rating (20 mA RMS), even momentarily, even in case of a short circuit. The current limiting effect is from intentionally large leakage inductance, controlled by laminated steel core shunts as described in one of Richard Hull's old FAQs. It's not from saturation; core is closer to saturation when open circuited than short circuited. Core flux is whatever it needs to be, for induced back-EMF in the primary to match ( applied primary voltage minus I * R drop in the primary winding ). As we turn up the load current, the magnetizing force from secondary ampere-turns cancels the magnetizing force from increase in primary ampere-turns.
All models are wrong; some models are useful. -- George Box
Matt_Gibson
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Re: HV power supply ideas

Post by Matt_Gibson »

A NST is probably the only thing that makes sense if you’re doing a demo fusor. For a neutron producing fusor, you’ll likely have to go the high frequency transformer plus multiplier route. If you could get ahold of an X-ray transformer, then you’ll have a much easier time.

I’d say that none of these are safe at all, but that would depend on your operating practices. Same idea behind proper gun safety…Proper storage and handling will lessen the chances of an accident, but no gun is fool proof nor (in my opinion) are any transformers capable of neutron production.

Since this seems to be your first push into high voltage projects, spend some time and thought on safe operating procedures and a safe work space. You don’t want to be fumbling around with shoddy electrical connections or sticking your hand into narrow places.
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