Pentode X-Rays!

Some 50kV fun with a PL504 Pentode...

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In this project, I use a leftover PL504 Pentode to create some X-Rays using the vacuum inside it.
DISCLAIMER: I am in no way encouraging you to try this at home, nor anywhere, the pentode emits X-ray photons up and down the spectrum which can cause harm. I am in no way responsible for your actions, don't try this anywhere.

As most of you know, when a sufficiently accelerated electron beam hits a target in vacuum, it releases X-Rays up and down the spectrum. I used that phenomena to create X-Rays using some leftover parts.

I saw some YouTube videos on how to create X-Rays using powerful vacuum diodes, got the idea, and then used a Pentode to recreate the effect at home.

  • 1 × A High Voltage Power Supply Any >20kV, >30W power supply, AC or DC.
  • 1 × PL504 Vacuum Tube Any tube that isn't gas-filled. (Pentodes, Triodes, Diodes...)

  • 1
    Step 1

    Get A Vacuum Tube!

    Almost every one will do the job: Pentodes, Triodes, Diodes, and even combined tubes are a good choice. Stay away from Nixie tubes, Voltage regulator tubes and Thyratrons!

  • 2
    Step 2

    Identify two electrodes on the inside of it that are close, but not touching. Then find the pins which are connected to them.

  • 3
    Step 3

    Connect the output terminals of the power supply to the two chosen pins on the tube.

View all 4 instructions

Enjoy this project?



greenaum wrote 11/15/2015 at 05:47 point

Might be a good idea to point your X-rays downward, on the bottom floor of where you live, so they're going into the Earth and nowhere else. That's assuming the rays don't just fly in every direction! You could perhaps check with some fluorescent material.

Just because you're only exposed for minutes, doesn't mean you're safe! There was an article on HAD about THERAC that killed people, or at least damaged them enough to die a short while later, using fairly short exposures. Safe exposure limit depends on power. I've no idea how much you're putting into your pentode, perhaps a series resistor would let you measure the current? Similarly a resistor divider might bring the voltage range into something you could measure.

Ionising radiation can kill you quick. It's not safe to mess about with.

  Are you sure? yes | no

Teodor Zafiroski wrote 01/07/2016 at 11:36 point

I tried to light up a fluorescent screen with it, but I got very little to no light from the screen, so I think it is quite safe.

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Richard Crowley wrote 05/07/2015 at 18:58 point

1) Electricity does not "pass through vacuum". But a sufficiently accelerated electron beam will.

2) Electrons passing through vacuum do NOT "release X-rays".  They must collide with a metal target ("anode") .

Suggest more careful research before making such claims.  Suggest learning about the hazards of ionizing radiation to your own safety before suggesting such dangerous experiments to others.

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Teodor Zafiroski wrote 05/08/2015 at 12:27 point

Thanks for pointing out my mistakes, I will edit the project details...

Also, I figured out that the DANGER tags are not very noticeable, so I added a disclaimer.

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J Groff wrote 02/02/2015 at 16:26 point

So I notice you put the 'danger' tags on. When I was a kid my dad, a dentist, got me some dental mouth slides, you know, those things they used to put in that hurt your mouth for x-rays. I had a 500Kv tesla coil driving a giant old surplus power triode. I took images of a mechanical watch that when developed, showed all the gears inside, right through steel casing. My dad congratulated me and said NEVER DO THAT AGAIN!

You are creating hard and soft xrays all up and down the spectrum. Its dangerous, limit your exposure.

BTW that glow that you see inside the tube on the glass is not exactly x-rays, its gas that has leaked in to the tube fluorescing and sometimes you can see it under normal conditions, a sign of a failing tube.

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Teodor Zafiroski wrote 02/03/2015 at 14:08 point

I limited my exposure to about 5 min. total time at a distance of half a meter from the tube. Won't hurt more than a CT scan! (I think...) :)

And for the glow... I first thought that it might be the glass luminescing because of the X rays...

  Are you sure? yes | no

Teodor Zafiroski wrote 05/07/2015 at 18:25 point

I was thinking if the vacuum inside the tube could be compromised, and concluded it isn't because the getter hasn't turned into oxide, not even a tiny bit. So I guess it's the glass after all....

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