## Xray high voltage multiplier

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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### Xray high voltage multiplier

Hi
With luck got my hands on xray tube with multiplier circuit.
I think its around 70 to 80 kv. Which is perfect for my fuser reactor.
My only concern is the transformer have three inputs.
I got a circuit diagram showing AC input with two wires
I have there in the board. Where to connect the AC .
Thanks
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C-W-Voltage-multiplier-circuit.png (27.46 KiB) Viewed 671 times

John Futter
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### Re: Xray high voltage multiplier

I think you will find that you have high frequency unit there
Designed to be driven at 30 -70 kHz
the three wires are likely to be for half bridge drive

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### Re: Xray high voltage multiplier

Hi john
So should I be using number 1 an 3 wires?
For the AC voltage . We are using 250v 50 Hertz where i live
Is this correct?
Thanks

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### Re: Xray high voltage multiplier

More detailed picture
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Rich Feldman
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### Re: Xray high voltage multiplier

I stand with John, in betting that you need a high frequency inverter between wall plug power and that transformer.

Suppose you want to give it a try with 50 Hz.

Step 1: measure the resistance between the three input terminals. That may prove or disprove that it's a center-tapped primary winding.

Step 2: Figure out how to apply 50 Hz limited to a few volts and a few amperes, whichever comes first. I bet it will be a few amperes, with less than 1 volt across the primary. Measure voltage at secondary terminals and multiplier output, and report the results here.
All models are wrong; some models are useful. -- George Box

John Futter
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### Re: Xray high voltage multiplier

All the clues are there
now calculate how much current you will have at the output if you use 50 or 60 Hz 220 volts
clue =capacitor value of 1000pf

for 50 /60 hz work I would expect 1,000,000pf or more per capacitor

you can try putting in your component values in to here
http://www.blazelabs.com/cw-brm-java.asp

Dennis P Brown
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### Re: Xray high voltage multiplier

I'd suggest you disconnect that x-ray tube before applying power; best to be safe than get a dangerous exposure. Also, be careful - caps charged to HV can deliver a dangerous shock. Small caps like that simply won't provide anywhere enough power to drive a fusor at 50 Hz. John is guiding you to this through "How to calculate" app.

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### Re: Xray high voltage multiplier

Hi all
Some people like to learn from there mistakes. Like me
Just went and connected it to 220v . But before that i added 2 fuses with 13 amps one on the circuit and one in the socket.
First time when powdered on had a boooof
Ok so i changed the fuse, and i thought because no transformer oil !
So i covered it in oil and had another boooof
The circuit still alive which is good.
By the circuit diagram it shows Ac voltage . Buy i think 220v
Is too much for it. Maybe it needs 110v?

Thanks for the help

Dennis P Brown
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### Re: Xray high voltage multiplier

Hello and learning by doing is ok for circuits and voltages that aren't lethal; unlike fusors. Can't say if yours is in that class but the last way one wants to prove that is via getting hit.

As such, I'd suggest (as others here have) apply a very low voltage - i.e. use a variac to control input voltage - if that x-former does use 110v AC (50/60 Hz), and you apply that voltage, the output will reach the rated value (possibly 70 kV.) Voltages above 25 kV do not behave in a fashion that one can easily expect; I developed a 100 KV voltage multiplier supply and I abandoned it after one use for that very reason. Far too dangerous and unstable to operate - that is, even under oil, the output was trying to reach ground.

Also, unless you have a very special HV meter (mine only goes to 50 - 55 kV) you need a low voltage input to that device so the average voltmeter (500 to 1000v) can read its output.

Blindly applying full voltage to an unknown voltage multiplier/transformer system isn't smart nor necessarily safe.
Last edited by Dennis P Brown on Fri May 08, 2020 8:55 pm, edited 1 time in total.

Rich Feldman
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### Re: Xray high voltage multiplier

Apparently the transformer-multiplier is not very precious to you.

110 V will surely give you another boooof result, maybe with one less o than 220 V. Why did you pick 13 A fuses, do you think the transformer primary can withstand any current-time combination that doesn't blow the fuse?

As mentioned before: if you insist on applying 50 Hz AC, and don't want to blow anything up, you need to limit the current. As with a ballast: incandescent lamp in series. I bet you will measure 219 V across the lamp and 1 V across the transformer primary.

Here is another view. The primary voltage which a transformer can handle, without core saturation, can be stated in volts per hertz. From the pictures, I will wildly guess that yours is good for 10 mV per hertz.
That means you can drive it with 220 V at 22 kHz, or 0.5 V at 50 Hz, plus some extra voltage to cover the I * R drop from resistance of the primary winding. You never told us what that resistance value is.

If the transformer were designed for 50 Hz, its core would be made of laminated steel instead of ferrite.

Nuclear physics experiments at home don't always require knowledge of electricity.
But fusors need more than some newcomers (and precocious high schoolers) want to bother with.
All models are wrong; some models are useful. -- George Box