CRT Tv based power supply

This forum is for specialized infomation important to the construction and safe operation of the high voltage electrical supplies and related circuitry needed for fusor operation.
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luke jarzebczyk
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CRT Tv based power supply

Post by luke jarzebczyk »

As most Crt tvs are now outdated many can commonly be found by the street and so they are a common and usually free resource for all attempts to tap into. Although I haven't personally found any that go to theses ranges research on the internet suggest that you can find some with voltages between 10-50 kv with the upper end being more than enough for most well built machines. The bonus of this is that when voltages are run in the opposite direction the electron gun component can sometimes be used as a Ion gun if you decide to use a Ion gun in your own design. If you want a smaller range old computer displays commonly come in the 30-40 kv range which is more consistent and can be sufficient for most fusion experiments.
luke jarzebczyk
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Re: CRT Tv based power supply

Post by luke jarzebczyk »

They are less common to find then they were a decade ago but many are still obtainable today.
Jerry Biehler
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Re: CRT Tv based power supply

Post by Jerry Biehler »

You will never get enough current out of one to be useful. These things put out microamps.
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Dave Xanatos
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Re: CRT Tv based power supply

Post by Dave Xanatos »

You CAN get useful voltage and current out of SOME flybacks, though. I wouldn't put much stock in old TV or monitor flybacks, but there ARE useful ones available if you're interested in using high frequency, high efficiency voltage generation. I'm working with one now from Information Unlimited in Amherst, NH. I'm using the "standard" ZVS Driver schematic (Mazilli oscillator, all over the internet) and tweaking it to drive two paralleled flybacks. Information Unlimited offers their high-output heavy duty 4000:1 flybacks - but they're pricey, about $80 each. I seriously burned my worksurface (I actually call these marks "tattoos" because they remind me of various projects :) ) with the output of one of these flybacks. There's NO WAY that only microamps would burn that deeply, that fast - I'm guessing at least 10 to 15mA, around 15kv right now (not measuring anything yet until I get "beefier" arcs), and I've just received my IRFP260 MOSFETs to upgrade the 250s in the original driver. I'm shooting for 40kv at around 30mA with these, using paralleled coils and very muscular drivers.

Video here shows an arc from one coil and the first iteration of the ZVS. You can see the burn I refer to above, immediately below the arc in the vid. Also listen to the high-pitched whistle from the driver/flyback.

https://www.youtube.com/watch?v=Zn5Xdoe08SU

Dave
It would take decades of work, by thousands of scientists, in a particle accelerator powered by dump trucks of flaming grant money! - Professor Farnsworth/FUTURAMA
DanielSandner
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Re: CRT Tv based power supply

Post by DanielSandner »

I completely agree that you can achieve high output and nice arcs, but the most common DC ones only deliver positive HV, you can't use them for a fusor. Furthermore i wouldn't use a ZVS with that much Power, in the end your flybacks will all die...
Daniel Sandner
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Richard Hull
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Re: CRT Tv based power supply

Post by Richard Hull »

All of this played out many times here. If your fly-back can pound out a continuous 600+ RMS watts without burning out or melting then it stands a chance, providing you are hooked up to some very special electronics.
Decent fusion has never been done with any fly-back. It has been done a number of times with a special HF transformer powered by 24kz or better electronic controlled power supplies. We await a major fly-back winner. They buzz around constantly like horse flies, but they never make it. In the end, they never measure a good voltage under a usable, stated load current for fusion.

Modern fly-backs all tend to have internal diodes forcing a positive output. They will never work. Older non-rectified fly-backs never had the guts or oomph needed.

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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Dave Xanatos
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Re: CRT Tv based power supply

Post by Dave Xanatos »

The flybacks I'm using are from Information Unlimited in Amherst, NH. They are very beefy, unrectified, and apparently designed to be seriously beaten on. Their secondaries have 4000 windings, and they state that they will do 40kv at 40ma. If I can get half of that with a ZVS (Mazilli Oscillator) driver, I'll be happy. My first, run-it-up-&-see-what-happens pass resulted in some nice arc that actually carbonized a deep chunk out if my workbench. It sounds like it's resonant around 15kHz or so. So.... I'm actually holding out some hope I might be able to get into fusion range (or at least into x-ray range) with these. If nothing else, it's a fun side/feeder project for my fusor. :) I'll keep everybody posted in case it turns into a successful output level.
It would take decades of work, by thousands of scientists, in a particle accelerator powered by dump trucks of flaming grant money! - Professor Farnsworth/FUTURAMA
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Dennis P Brown
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Re: CRT Tv based power supply

Post by Dennis P Brown »

Air arcs mean little; a hot, ultra high pressure plasma can conduct far above what any device could normally provide - note a NST can provide very large, long arcs in air and are worthless as a fusor supply since their current is too low. That said, I have one of those fly backs and it is a joke compared to a real x-former that provides 30 kV at up to 25 ma continuous. So, try it but don't expect much - never use an air test to determine performance (you will be fooled) - must be in the 5 - 20 micron range to gauge its real characteristics. As for the ZVS circuit, most people use batteries to power these (the example I saw used two large and beefy marine types, no less. In this manner they provided high current to the ZVS. Not sure that investment is worth it just to get a short time test.) Do try and measure the current/voltage in a real vacuum environment but don't count on more then a few ma in the 20 kV range; less if pushed into the 30 kV's would be my guess. Hope you prove me wrong!
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Richard Hull
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Re: CRT Tv based power supply

Post by Richard Hull »

I forever remain amazed at claims with no voltage actually measured at a claimed current which is also never measured.

The current and voltage at high voltages is a snap to measure by anyone with just very minimal skills.

I can make an ad-hoc 0-50kv voltmeter with a free (no Charge Harbor Freight DVM and a few high ohm resistors. A second Harbor Freight free meter can mesure current with no modifications whatsoever! The entire effort would take about 10 minutes from no proper metering to full 50kv @ any realizable current measurement system.

Claims without the slightest attempt at measurement........

Such claims are usually made by folks who have an AC arc with no capability of proper rectification and filtering on hand to cover the DC voltages and currents they are claiming might be had. Hot flaming air arcs mean nothing beyond a WOW! I have videos of a 16 kv 2kw potential transformer that we "played with" in the 90's allowing a really evil white hot arc to be pulled out to 4 feet in length as an insulated rod with the hot lead is drawn away. We know that a voltage of 16kv will not leap across a cold air distance of 1 inch... Air arcs mean nothing.... burn spots mean even less.

Properly conducted measurements always mean something and tell the tale..

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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