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Dennis P Brown
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Re: Greetings!

Post by Dennis P Brown » Tue Jun 27, 2017 10:36 am

Good post on your part (except the wrong forum!) and it is important to know what does what in a very high voltage and power transformer before connecting any input power! Again, that transformer can be lethal when energized; as Richard mentioned and you need to do, get a variac rated for the required power and voltage to control the input to the transformer - I will not waste time explaining these ideas; you need to study up on x-formers, how they work (basics, not detailed theory!) before attempting any wiring or testing. When testing, use the smallest possible input voltage to keep the x-former output low enough to be "relatively" safe. There are a huge number of youtube and other sites that explain transformers operation/theory in many levels of detail. Visit some and study this subject - including rectifying x-former outputs. These basics must be learned to even begin to be safe around such lethal devices like an x-ray x-former.

Your statement
If I'm inputting DC current because of the rectifier

indicates that you don't know much about simple electrical theory of circuits/devices. You are dealing with exceedingly dangerous and lethal devices when building a real fusor. You get no second chances if you make a mistake with an x-ray x-former nor radiation above 25 - 30 kV. You really must read all the related FAQ's and study these subjects like x-formers!

The x-former, and diodes will need to be under oil (especially when used for a fusor supply or for any high voltage work; not necessarily needed for testing at lower voltages (say, a few kV or under) and very low power draw); however,one does not just place a x-former in oil. There is a procedure so research that in this forum and learn about that subject.

Richard raises a good point - whether the x-former can output 10-20 ma at 20 kV. This will be determined by the rated x-former power. Exceeding its rated load can quickly burn out a x-former (another reason these are placed under oil; to help with heat load, besides helping to suppress voltage shorting between the HV secondary winding's.)

Be aware that diodes have to be rated to handle the max voltage and an AC voltage has a rated value and a peak value - your diodes must be rated for the peak, not average voltage. If this isn't clear, you need to read up on this subject as well. A ballast resistor for the x-former output is another issue you will need to know but not important yet; however, Richard covers that subject in detail in the FAQ's so do read that.

Also, as Richard said, get your He-3 detector working - that will educated you a great deal on high voltage systems (in the low kilo-voltage range) that is also low current. Once you get the He-3 detector going, calibrating it for background and signal is very useful. If you have funds to burn, possibly consider renting (for six months so have the detector working first!) a powerful (but legal and safe) polonium source. Combined with a very thin and small (!) sheet of beryllium (extremely toxic so know the safe handling and disposal of Be!) and one can have a safe and low flux neutron source to calibrate the detector. However, getting a bubble detector is the easiest (but these are a little pricey) way to calibrate a detector but that does require that one has a working fusor ... .

Consider getting some type of Geiger-counter to scan for x-ray issues around your chamber. A surplus unit (ancient CD units) that works (can be rather low cost) is all one needs. A uranium ore (small amount; Richard sells these) can be used to confirm proper operation. This need not be calibrate - just knowing roughly if there is an x-ray flux is what's critical. Shielding isn't very difficult; I use sheets of slate available from any home depot - extremely cheap, non-toxic (unlike lead), easy to cut (use an abrasive blade) and can be stacked/glued together to form thick enough shielding for any x-ray threat. Doesn't conduct so safe around high voltage.

From now on, post your questions in the appropriate section; this belongs in the High voltage forum.

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Joshua Turbyfill
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Re: Greetings!

Post by Joshua Turbyfill » Wed Jun 28, 2017 9:47 pm

I was talking about putting a 20A 1000V rectifier between the variac and the transformer. According to the seller on eBay the transformer will operate on a pulsed DC input and then output DC. As such I'll just use one of the inputs and one of the outputs unless that ends up being idiotic in some way, and add some ballast alongside the metal oxide varistor. I'm aware of the degassing and drying process for the oil, however I'm not finding proper transformer oil anywhere so I might end up using mineral oil, with active cooling and maybe mA and voltage readouts if I really need them. And with some more research I'll probably end up changing a few things but either way I'll get this properly setup soon. On another note, slate sounds like a great alternative to lead, but I wonder how much neutron radiation it would block at 60kV. Either way I might just skip shielding all together and operate from 50-70 ft outside. I'll keep the rest in mind, thanks.

John Futter
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Re: Greetings!

Post by John Futter » Thu Jun 29, 2017 2:03 am

Joshua

WHOA
What a lot of bullS&*T

Time you learn't what to do before blowing up your local supply transformwer making your house and several others dark because of back feeding DC into a supply transformer. sometimes 1 -2 amps of DC is all it needs to saturate the core and BANG Darkness

You need a mentor before going further ---for your own and others safety

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Dennis P Brown
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Re: Greetings!

Post by Dennis P Brown » Thu Jun 29, 2017 10:03 am

John is correct and please take what he says to heart; do not blindly add power to such a x-former. Getting help, as John has suggested is a good idea.

Also, not aware of anyone cooling x-former oil for a fusor; the power draw is just too low - my x-former is air rated and I added a fan just to be careful. But mine is NOT an x-ray transformer, however.

You can post questions about how to wire your high voltage x-former in the fusor power section (High voltage section.) Also, one uses a vacuum to get a x-former transformer (really within its winding's) to fill with oil so there are no trapped air pockets. Drying should not be an issue. I use synthetic motor oil (extremely good for HV; there was a study done so this isn't just wag) but most here use mineral oil or proper x-former oil - always a good idea when one isn't experienced.

Again, never just try stuff with such a lethal x-former. One needs proper proper cabling (60 kV is not cheap or easy to make connectors), oil tank for the x-former, ability to measure the input voltage, output voltage and currents and have a safe way to load the system. These are not easy tasks even for someone experienced - I spent over a month setting up and testing mine and I had both a lot of HV experience and a nearly turn-key system!

I strongly suggest that you get a cheap neon sign x-former (NST) and use that to test and gain experience with high voltage systems - powering, measuring and creating rectified outputs. A NST is a far safer (but even those can be dangerous if one is really careless - I am not saying they are fool proof.)

Calculating the stopping thickness of slate for a 80 keV X-ray (safety factor!) is trivial (called google.) Slate can be drilled so bolting in place is easy as is stacking. I will say that remote operation is not easy for an expert and no way a novice has the time and patience to remain that far away (and frankly, you haven't looked into x-rays if you think that distance is required.)

Again, as John added, you need to get a mentor; also, I feel you are not studying the issues carefully enough (taking what that person said about the x-former and not know that wasn't correct indicates you know very little on that subject.)

Learning is critical if one wants to be: 1) safe 2) not killed (ok, really part of one) and 3) ever get a fusion system up and running. Having little knowledge/experience is how we all start. The difference in people who make successful fusor's and those that don't is often that successful people read, study, practice/experiment on simple systems and work their way up to full level systems - buying advanced equipment and not understanding the HV power systems is a dangerous approach. What you have is not turnkey and you really need to learn about that system before attempting to construct such a dangerous x-former system.

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Dennis P Brown
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Re: Greetings!

Post by Dennis P Brown » Thu Jun 29, 2017 1:42 pm

A few more thoughts: first, please start posting in the correct forum! This is really for introductions only.

Next, consider buying a turnkey supply like a Spellman or Glassman that can supply 30 - 40 kV at 10 -20 ma (at least. Check the power rating before buying and the polarity! Negative only (but some allow both which is ok.) Also, make sure you get a working unit with the proper control electronics (some higher wattage units have separate control boxes and main supply box.) Also, you will need a proper cable (rated to handle the max. voltage) and a vacuum feed-thru (also correctly correctly rated.) Sell that x-ray transformer to someone with the knowledge to work with it safely.

Finally, maybe focus for now on other issues like the neutron detector and gas supply since these are both critical and needed as well. This will allow you to both gain experience and knowledge to help you handle HV issues when you get ready for that part of the project.

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Joshua Turbyfill
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Re: Greetings!

Post by Joshua Turbyfill » Thu Jun 29, 2017 2:47 pm

Dennis, I understand these things. Do you think I would jump into such a complex project without proper research? I only posted that question here because of how confused I was about that guys instructions, I wanted to know if they were legitimate since they obviously differ from how you all seem to be doing things, as well as pretty much every other reference online. In a couple of weeks I'll post my nearly-finished or maybe even completed fusor build.

And thanks Matthew for clarifying that it about the inputs.

Regards,
Josh

Andrew Seltzman
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Re: Greetings!

Post by Andrew Seltzman » Thu Jul 20, 2017 2:15 am

As far as the wires go, the bare wire connected to the frame is secondary ground, the 2 bolted ones are AC input. For the secondary outputs, the copper pad is the output of one secondary, the other two pins on the other secondary are the filament winding in series with the other secondary. Check with an ohm meter that they are connected to the black insulated wire on the back of that secondary, if so connecting to either of the two pins or the black wire would give the HV output of that secondary.

Remember that that transformer can only give -60kV with respect to ground. The secondaries produce AC that is 180 degrees out of phase, or 120kV differential between them. In the x-ray tube this would produce 120kV x-rays, but once rectified with diodes for a fusor it will only give -60kV peak DC. The secondaries can not be connected in parallel as this would cause a short, nor can the core ground be floated as it would arc to the primary.

I would also recommend what others said about going with a spellman supply, they are pretty common on ebay for a reasonable cost and will give you a much nicer, regulated DC output with short/arc current limiting. Here's a -30kv one, though I'd hold out for a -40kv one with at least 5mA output (the PTV40n200x2113) is a nice supply that will definitely give you detectable fusion.
http://www.ebay.com/itm/Spellman-PTV30N ... SwyWZZQHPl
Andrew Seltzman
www.rtftechnologies.org

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