Precipitator power supplies?

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ian_krase
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Re: Precipitator power supplies?

Post by ian_krase » Wed Jun 07, 2017 11:10 am

You're saying that to use this in a (conventional) fusor one would ground the, well, ground, and then use the negative 30kv output to drive the grid (And yes, that does sound rather low, and low current to boot)

Is that correct?

This suggests that an unconventional system (i.e. one with different grounding requirements) might use both ends properly?

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Dennis P Brown
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Re: Precipitator power supplies?

Post by Dennis P Brown » Wed Jun 07, 2017 12:41 pm

To use this power supply for a real fusor one needs a couple of things (previously mentioned in this thread.) First, one MUST get a negative output from this wildly swinging AC source so diodes (at least two but a bridge could also be done) are required; and second, a ballast resistor to prevent a massive over current flow when a plasma first ignites. The resistor issue is well covered in the FAQ's on power supplies. Of course, the diode as you may or may not know is seeing a higher peak voltage than the max rated voltage for the supply (for any AC powered device) so these diodes must be rated for the higher voltage with some safety factor. As for grounding, that is an issue but that depends on the supply - the fusor's chamber itself (generally) is the main ground. Grounding a flyback isn't a straight forward thing to do. Yes, the case should be grounded but most flybacks I've seen (not too many, however) float. Other's can weigh in on that specific topic.

Aside: don't underestimate the lethality of flybacks - even if the unit can't do fusion that PS will be deadly with anywhere near that power. Use proper cables and follow all standard HV safety protocols.

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Re: Precipitator power supplies?

Post by Jerry Biehler » Wed Jun 07, 2017 3:27 pm

Wildly swinging AC source? This unit should be DC out. Precipitators dont work on AC. The negative size goes to the wires in the collector and positive to the plates where the particles are collected.

Those transformers probably have diodes built in.

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Re: Precipitator power supplies?

Post by John Futter » Wed Jun 07, 2017 6:50 pm

Ian
No you would connect the positive output to ground and the negative output to your grid, but because of what i said earlier this may compromise
creepage distance on the PCB and the flyback transformers winding to core
they certainly dont cost much so it is worth a try

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Re: Precipitator power supplies?

Post by Shireesh Apte » Sun Oct 29, 2017 2:01 am

This is the high voltage unit I have recently used to generate a plasma at 100 microns pressure. If the specs are to be believed, this unit may be capable of (mid-range) 30 KV and 10 mA. By all accounts, from whatever I have read on the FAQ posts, this should be good enough to detect fusion. By the way, my plan is to use a silver sample contained in a moderator (i.e a water bath) so as to allow the (slower thermal neutrons) to convert part of the silver to cadmium and emit gamma and x rays that I can detect with a Geiger counter.
I will of course devise methods to measure the actual voltage and current for the fusor part of my project.
Thanks and Best regards,
Shireesh Apte
electrostaticprecipitator.jpg
High Voltage Electrostatic Precipitator Power Supply with 400W 60kV

Specifications

1.Input voltage AC160V-260V

2.The output voltage is DC5KV-60KV, adjustable speed

3.Output current 8-12mA

4.Size: 230*180*80mm

5.Weight 1.78KG

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Finn Hammer
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Re: Precipitator power supplies?

Post by Finn Hammer » Sun Oct 29, 2017 7:32 am

Gods speed to you, for testing this supply.
Those of us who has had access to better supplies like Spellman et al will tend to disbelieve the suitability of it, with regard to delivering, in particular, the voltage. I doubt it too, due to experience with similar supplies, where corona issues, and tracking, put an end to the transformers. But this is speculation, whereas nothing beats hands on experience, and you are getting it.
Looking forward to read your results.
Cheers, Finn Hammer

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Richard Hull
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Re: Precipitator power supplies?

Post by Richard Hull » Sun Oct 29, 2017 9:11 pm

Those flybacks look like the type with diodes in them. If those are repurposed TV flybacks, the voltage out is positive. I suppose a manufacturer might have special negative polarity diodes potted into them. Like Finn, I hope you efforts pay off. Keep us in the loop and report your efforts as they go.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

Shireesh Apte
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Re: Precipitator power supplies?

Post by Shireesh Apte » Mon Oct 30, 2017 2:29 am

Thanks Finn, Richard,

My students rigged the potentiometer knobs with a short piece of tubing into which glass rods were inserted (attached). These glass rods project out of two holes in a wooden enclosure made from waste oriented strand board that I scavenged from Lowes. I will post a photograph next week. I am a novice at circuits (as with almost everything else - as I have found that Knowledge is essentially a black hole) but so far- my method has been NOT to touch ANYTHING once I have it fired up. I am learning as I go - I realize this is dangerous; but as the man said - D-day might have been under entirely different circumstances had Eisenhower waited for the weather to clear.
The safety of my students is my primary concern and I take that very seriously - even with the more zealous (Instant gratification) types - as I seem to have this year helping me on my 'Star-in-a-jar' and 'fusor' project.
I will post detailed pictures of my set up in the 'construction' part of the forums next week.
By the way, my expertise (such as it is) lies in the field of Pharmaceutical excipients -having worked for over 20 years in the pharmaceutical industry - and you can find many of my manuscripts in the peer-reviewed journal I run: https://jefc.scholasticahq.com
Thanks again.
Best,
Shireesh

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Dennis P Brown
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Re: Precipitator power supplies?

Post by Dennis P Brown » Mon Oct 30, 2017 10:29 am

I have my doubts that 30 kV at 10 ma is enough to activate Ag that is detectable (if that supply really is providing enough average power to really provide a full 300 watts - as I said previously, being an AC driven system (the flyback), the output current is varying a great deal so the real average power could be less than that simple calculation would lead one to believe.) That said, since you came this far, might as well try it. However, if you are unable to detect activation of Ag, that does not necessarily mean you've had no fusion (if your real power is three hundred watts you likely have some not insignificant level of fusion.) So, don't be discouraged. Detecting neutrons is not easy.

I say this because I can easily detect fusion neutrons using my Russian boron-based gas filled tube and my fusor power is 1500 watts (or more) but I can't activate Ag enough to detect it using a Geiger tube. That could, partly be geometry issues but still, in the FAQ's, three hundred watts is not considered enough to activate Ag, if memory serves.

That all said, how are you going to measure both the voltage and current of that power supply? Knowing those values is essential to determining if the supply is even capable of being used for fusion and is delivering those values to the plasma. I ask this because determining that this flyback based supply can deliver that level of power would be a very useful contribution to this forum.

I may have forgotten if you already talked about this topic but what type of chamber are you planning to use? Saying "star in a jar" is not reassuring ... if you get my drift.

Finally, I know only what you posted and what the picture shows about that power supply - the two input points (if they are) then require a single phase source, which means you need 208 AC single phase - that is not routinely available. Three phase 220 does not appear to be supported by that supply - hopefully, that isn't the case. But since you indicate you know little about electricity, that is a rather critical issue if you plan to power that specific supply (single phase 120, if the documentation is correct, will not be sufficient.) Maybe check the instructions and confirm that input issue.
Last edited by Dennis P Brown on Mon Oct 30, 2017 11:02 am, edited 2 times in total.

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Finn Hammer
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Re: Precipitator power supplies?

Post by Finn Hammer » Mon Oct 30, 2017 10:54 am

Shireesh,

For your consideration, here is an image of the voltage divider I use for my high voltage work. It is shown hooked up to another Precipitator supply that I am evaluating for a precipitator project I am associated to.
It is a 20.000 : 1 divider. The high voltage resistors are 1% 20Mohms, 10 of them, the bottom resistor is 10Kohm.
The resistors are terminated in 6mm brass balls, and there are potential rings at the top. I should have completed the rings all the way down, but got distracted.
It is fine for DC work, but lacks compensation for AC work, where a sophisticated arrangement of parallel capacitors would be needed.
Feel free to replicate, It will serve you well.
IMG_20171030_113626.jpg
Hope this helps

Cheers, Finn Hammer

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