Seems too good to be true

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charlie_mccartney
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Seems too good to be true

Post by charlie_mccartney »

http://www.ebay.com/itm/CPI-Advanced-ne ... 2a2da5dd45

I need a NST for a demo fusor and I found this and was wondering if it is legitimate or is there something wrong with this.
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Carl Willis
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Re: Seems too good to be true

Post by Carl Willis »

This is not a transformer. It's a high-frequency inverter-based "neon power supply". Your clues are the weight, the shape, and the absence of ceramic insulators for the output. Unfortunately, these supplies are of no known utility in the fusion hobby. You need to locate a real transformer. They are not in short supply.

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Re: Seems too good to be true

Post by Jeroen Vriesman »

This is what I did to get a NST's:

Call a neon-sign production/maintenance company.

They usually replace the old real transformers with modern "electronic transformers" (= switched PSU), so the old transformers pile up, close to my work there was such a company, they had a pile of more than a few hundred old NST's!
I got 5 for free, 2 of them worked.
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Chris Bradley
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Re: Seems too good to be true

Post by Chris Bradley »

Carl Willis wrote: Unfortunately, these supplies are of no known utility in the fusion hobby.
That's not entirely true, Carl. They can be made to deliver the desired voltage, power, polarity/earthing, etc., with appropriate external circuitry. The level of control achievable on that voltage and power is, however, somewhat dependent on the specifics of these types of inverters, but is usually within the realms of 'do-able'.

However, for the purposes of new-comers who have to ask the question, I agree that they should be overlooked in the first instance, in preference to much simple routes. But the reality is that iron-cored transformers are getting rarer and rarer (unless you have a friendly neon sign shop nearby, it seems!!), and at some stage folks (other than only myself) will have to start using this type of device and learn how to build an HV circuit around it, for want of those simpler options.
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Carl Willis
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Re: Seems too good to be true

Post by Carl Willis »

Okay Chris, show me where someone powered a fusor with a neon inverter.

Sometimes things get past me, but at last count, the number of successes was zero point zero.

I'm sure it's not for lack of familiarity that these are poorly regarded in our community and the Tesla coiling community and the HV hobby generally; they're cheap, they've been around a long time, and lots of people have had fun burning them out. I had about a half-dozen of blown ones in a box at one point, awaiting my interest in salvaging them for anything of residual value (I ended up throwing them away). I'm sure it's not strictly impossible to make these pigs fly. I'd argue that it's not a diversion that would appeal to a beginning fusioneer.

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Dan Tibbets
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Re: Seems too good to be true

Post by Dan Tibbets »

I actually MAY have used a transformer similar to this (?). It is an 18,500 volt center taped oil burner electronic transformer rated at 23 mA and 20,000 HTZ.
It would produce a steady glow discharge in a Demo fusor once the Variac was turned up past ~ 60 volts input. On an oscilloscope the wave form was a bunch of cycles covering the upper ~ 1/3 of the sine wave (presumably ~ 20,000 HTz), then a pause till the next ac peak. So I think it was putting out ~ 20,000 HTZ voltage for ~ 1/3 to 1/2 of each half cycle.

It seemed to follow ~ the 2/3 current rating - 1/3 voltage drop pattern.

I had it on a full wave voltage doubler at one point with a stage capacitance of ~ 1 nanoF. It would maintain reasonable voltage up to 5-10 mA (presumably due to the high frequency -part time)as measured by a DC voltmeter. With an old fasioned NST, the same multiplier resulted in severe voltage drop at currents well below 1 mA and I could only obtain feeble glows). One nanoFarad capacitance is much to small for a 60 HTZ input, but for the (part time) 20,000 HTZ input it worked.

My recollection is that the oscilloscope wave form after the multiplier was not flat but somewhat sawtooth with increasing current, but still it functioned for a demo fusor. I suspect the average dc voltage may have been closer to ~ 1/2 of the peak dc (Meter measuring near peak?) so actual perceived voltage based fusion efforts would suffer.

I have wondered if several of these electronic high voltage 'transformers' could be hooked up in parallel (in phase or out) to generate both adequate voltage and current for actual fusion. Might they fry each other? Could they use a common multiplier or should separate multipliers be used with merging of the dc current after the multipliers?
An example would be two 17,000 volt oil burner electronic transformers rated at 45 mA each. With full wave single stage multipliers with easily obtained high voltage capacitors of reasonable capacity, a peak DC voltage of up to ~ 22,000 volts might be obtained and there may not be too much voltage drop at currents of up to ~ 20-30 mA.

Ground fault features might interfere, though the single ignition transformer did work in my dirty demo fusors.

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Chris Bradley
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Re: Seems too good to be true

Post by Chris Bradley »

Carl Willis wrote:these supplies are of no known utility in the fusion hobby. You need to locate a real transformer.
Carl. I have demonstrated, and well-reported, my supplies to 60kV and 10 mA continuous output. If this is 'of no known utility' then feel free to explain why not.

The tested levels I have worked to is limited only by the number of modules I have made. They are modular and the whole design purpose is that they can be stacked in serial and parallel to make whatever voltage or current combinations you want, within the stand-off voltages of the capacitors chosen.
Dan Tibbets wrote:I have wondered if several of these electronic high voltage 'transformers' could be hooked up in parallel (in phase or out) to generate both adequate voltage and current for actual fusion. Might they fry each other? Could they use a common multiplier or should separate multipliers be used with merging of the dc current after the multipliers?

Not quite 'in parallel', Dan. I have explained how to do this in my patent application, which is in the following post:

viewtopic.php?f=11&t=4887&p=27725#p27725


In the case of simplifying the output/circuit for a transformer such as the one shown above, which might be more 'do-able' for the first-timer, the two-stage circuit in the following post can be used:

viewtopic.php?f=11&t=4882&p=27720#p27720


The control over the output voltage will depend on the exact functionality of the inverter used. Some will happily work over a range of input voltages from 30% to max, whereas others may be much more limited. Obviously, you want to pick inverters with the widest operating voltage range.


Carl, I've put years of effort into the developments I have created, and patents applied. I can assure you the above circuits are a means to make use of such inverters for the output of 10's of kV at robust continuous current outputs. These power supplies I have made have been the only ones I have been working with, above 10 kV, throughout my work. They are cheap, compact and easy to control because they are essentially 0 to 12V -> 0 to 30kV floating DC-DC converters.

Carl Willis wrote:I'd argue that it's not a diversion that would appeal to a beginning fusioneer.
I've already made the point that they shouldn't see it as an appealing approach, so I sort-of agree with you (though I'd not write it in such a prescriptive form as to argue what is or is not in the mind of someone else).

I'm not encouraging a beginner to go ahead with the circuit unless they are confident with electronics, and that they should stick to simpler things that are available. Voltage control is an obvious issue that is made simple by basic transformer types, but it is not insurmountable if they have the skills and/or commitment to making it work.

I do not side with the view that nothing is worth trying until someone else has tried it first. This is a recipe for doing nothing new.
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Carl Willis
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Re: Seems too good to be true

Post by Carl Willis »

Good grief.

"NST": A true transformer operating at 50/60 Hz, referenced in various FAQs and many demo projects.
"Neon power supply," as linked in the original post in this thread: an off-line-powered high-frequency inverter with a balanced, center-grounded output, made specifically for driving neon tubes. The thing the guy thought was an NST, in common with many others before him.

Chris, kudos on your CCFL inverter power supply. A twenty-one gun salute with four hundred ruffles and flourishes on the patent for it. Now that the requisite pomp and circumstance are out of the way: satisfy yourself that it uses inverters that are relevantly different from the type referenced in the original post, to wit, the "neon power supply" that the guy was about to purchase. Among other differences, your CCFL inverters' outputs are not centered around a ground reference (indeed, your schematic requires this). They probably have no fault shutdown circuitry. They obviously operate at much lower voltages than the neon supplies.

I'd love to see you try a neon inverter in your multiplier circuit, in place of the CCFL inverter. You might learn something while waiting for the smoke to clear.

-Carl
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Chris Bradley
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Re: Seems too good to be true

Post by Chris Bradley »

Carl.

It seems dichotomous that on the one hand you seem to want to stick with answering the first question 'No, it's not an NST', which would be a fair enough point, but you are moving on to discuss/ask other points.

I'll happily address your points, if you like. Feel free to add to one of the existing threads on using this capacitive coupling method (and, yes, works for any AC output, from any source).

I was trying to offer something constructive, and a new insight which I have tested through, but this thread is now of an 'adversarial' nature that I now have zero interest in it.

You're right, the thread is simply 'is this [above] NST OK', the answer to which is 'it's not an NST'. Can we close, and agree amicably on that?
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Re: Seems too good to be true

Post by Carl Willis »

Chris,

My goodness, you do have a short-term memory problem today.

The reason your power supply is being discussed in this NST thread is evidently because you brought it up. Now there would be nothing wrong with bringing it up as an alternative, but the reason we're in this donnybrook is because of your implication that it works with the neon power supplies that the fellow linked, that my dismissal of the neon power supply was "not entirely true" based on your experience. So, logically enough, we're at that point in the discussion where you are being asked to put up or shut up. Put up a link showing your power supply running with neon inverters, or go back and qualify your claim about my untruthfulness. THEN we can close. (Not amicably of course; too late for that.)

-Carl
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Re: Seems too good to be true

Post by charlie_mccartney »

Thank you for showing me the grave difference between these two different HV power supply's.
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Re: Seems too good to be true

Post by Richard Hull »

I will not enter into the argument above, but suffice it to say the average cheapo switcher type neon replacement is not suitable for demo fusor work. Some may be marginally acceptable as Chris notes, but do you want to experiment with your own money to try and find one that will sorta'' work for you.

Classically these modern cheapo substitutes are not adjustable. ( full voltage or none at all.) Many of the cheap electronic switchers don't come on at all with lower voltages, but snap on at some minimum line voltage and may only allow a limited range of variability with lower currents at those voltages.

Save yourself time and effort and get a real honest to God neon transformer that is warranted to work over a full adjustable range of 0 volts to its kilovolt nameplate rating with no load. If what you buy doesn't weigh 15-40 lbs you are not getting a real neon transformer and must suffer under the yoke of whatever you do get.

Finally, no fusing fusor will work well with even a real neon transformer! Only a demo fusor will work using a neon transformer, but it is only guaranteed to work as long as you use a real neon transformer. Buy anything else for your demo system power supply and you are on your own.

I am going to work up an FAQ on this with the why's and wherefores.

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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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