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Driving X-Ray tube with ignition coil.

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zippotix

Wed Nov 05 2014, 11:12AM

Registered Member #5208 Joined: Thu Jun 07 2012, 06:12PM
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Posts: 86

I found a V1-0,15/55 kenotron tube for a nice price (2 USD equivalent) and bought it. Will this tube produce enough X-rays to make some thrashy looking radiograph? Or at least some fluoroscopy?

zippotix

Fri Nov 07 2014, 01:04PM

Registered Member #5208 Joined: Thu Jun 07 2012, 06:12PM
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Posts: 86

Sorry for double posting, but WOW! In hot cathode mode this thing is quite powerful! CCD gets overloaded at 20-25 cm distance.

Conundrum

Sat Nov 08 2014, 02:43PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Um.. please tell us you have proper shielding, at this level radiation sickness is a real concern.
Certainly the CCD can be damaged and my phone actually has permanent dead/hot pixels from being used as a "test dummy" behind 5mm of lead sheet using nothing more than a 5642 diode as X-ray source and a 48V powered gas igniter transformer for under 5 minutes.
My counters were registering high enough to be a concern even with such short pulses, and the radiation even permanently scrambled a 32GB test card resulting in all the data being lost.

See

zippotix

Sat Nov 08 2014, 06:53PM

Registered Member #5208 Joined: Thu Jun 07 2012, 06:12PM
Location:
Posts: 86

Of course, I have 3 small blocks of lead, blocking whole lamp exept one side, which is "hot" side. I myself hide behind wall (there's also fridge and furnitures along the way).
I know CCD gets dead pixels, this is old phone so I don't care really :D. I would like to have some way to measure the intensity, but all I have is old army GM counter and it's not that good for X-rays.
Here's my lamp, operating at 50-55kV plus 5vac at filament

GrantX

Sun Nov 09 2014, 07:11AM

Registered Member #4074 Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335

zippotix wrote ...

Of course, I have 3 small blocks of lead, blocking whole lamp exept one side, which is "hot" side. I myself hide behind wall (there's also fridge and furnitures along the way).
I know CCD gets dead pixels, this is old phone so I don't care really :D. I would like to have some way to measure the intensity, but all I have is old army GM counter and it's not that good for X-rays.
Here's my lamp, operating at 50-55kV plus 5vac at filament

Hmmm, it still seems like a scary amount of radiation. I once fired up an old Russian 5kV voltage stabilizer tube in cold cathode mode and tried to film it. I applied perhaps 30-40kV from a pulsed induction coil capable of about ~2mA at short circuit (when cranked way up to 100-120kV). I didn't really see many white pixels at all, but my CDV-700 detector freaked out and the needle swung up with frightening speed.... I never did it again.

Enough radiation to completely overload the CCD in your camera is terrifying. I'm not an expert by any means, but it sounds like you could end up with X-ray burns on your hands, or carcinoma if you keep exposing yourself. If I were you I'd weld up a small chamber out of 6-10mm thick mild steel, then stack it with as many lead bricks as humanly possible. And then stand on the other side of a brick wall two streets away, haha ;)

But, as I said, I don't know much about X-ray dosages and how it correlates to biological effects, so perhaps I just scared myself for no reason (if there's not many white pixels showing up the emissions can't be too intense, correct?)

zippotix

Mon Nov 10 2014, 01:10PM

Registered Member #5208 Joined: Thu Jun 07 2012, 06:12PM
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Posts: 86

No no, I don't expose myself, the lead blocks are few centimeters thick. I would think they completely, or at least in 99%, block all radiation. I also leave the room :). Nice idea with small chamber, I will have to do something like this, I don't like the idea of them x rays scattering about.

If you don't see much white pixels it could mean two things I guess:
1. Their kinetic energy is not high enough to pass through the plastic housing and lenses, but they can be absorbed by your body, someone above said that low energy photons are worse than those of high energies.
2. The voltage is not high enough for x rays to get through the glass of the tube.
At least that's what I think, we'll have to wait till some expert chimes in ;).

Ash Small

Mon Nov 10 2014, 01:53PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Maybe the easiest way to determine approximate dosage/exposure would be photographic film/paper. A darkroom is easy enough to set up. There may be some other useful info here:

Also, what's on the other side of the wall? are you sure you're not irradiating next door's cat/kids, etc?

zippotix

Mon Nov 10 2014, 03:30PM

Registered Member #5208 Joined: Thu Jun 07 2012, 06:12PM
Location:
Posts: 86

Thanks for suggestion Ash, but to get really accurate readings I can't think of anything else than a scintilation counter. And they're expensive ;). I just treat it as if it outputs 5000R/h. On the other side of the wall, there is a road, and a big prewar building, kind of private hospital, made of thick red bricks. They have CT and regular x-ray there too, LOL!

klugesmith

Mon Nov 10 2014, 05:39PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

zippotix wrote ...
... I would like to have some way to measure the intensity, but all I have is old army GM counter and it's not that good for X-rays.

X-ray dose units are based on ionization of air. So are most civil defense radiation meters.

To get quantitative in your lab, I suggest a pen-shaped fiber dosimeter, which you can buy on ebay, and a recharger which you could make.
Most CD dosimeters have full scale range of 20 or 200 roentgens, but there are some training units available with 200 mR range.
My dentist gave one a "normal" exposure and the dosimeter registered a change of about 10 mR.
Remember that's not the dose to patient's whole body -- only a few grams of tissue are in the beam.

Did some experiments at home with a Coolidge tube and 15 kV NST. Full-wave center-tapped rectification produced about 10 kVp, and the x-rays apparently could not penetrate the dosimeter's aluminum tube. Running the tube between the two "hot" sides of NST, with a floating filament supply, gave about 20 kVp and the dosimeter responded briskly.

Here is a homebrew motor-generator being used as a filament PS with high voltage isolation. Made me proud of my username here.

zippotix

Mon Nov 10 2014, 05:43PM

Registered Member #5208 Joined: Thu Jun 07 2012, 06:12PM
Location:
Posts: 86

I have a quartz pen shaped dosimeter, but I totally forgot about it. It can be charged by my GM counter, there's special socket for this.
Now I tried to light up a intensifying screen, sensitivity of 400, Kodak green, but it failed. Hmm, either the voltage is not enough (55kV) or this tube requires DC. But it still should light it up, at least a bit.

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