Building A Miniature X-ray Tube


We’ve seen homemade x-ray devices and we’ve seen people making vacuum tubes at home. We’ve never seen anyone make their own x-ray tube, though, and it’s doubtful we’ll ever see the skill and craftsmanship that went into this build again.

An x-ray tube is a simple device; a cathode emits electrons that strike a tungsten anode that emits x-rays. Most x-ray tubes, though, are relatively large with low-power mammography tubes being a few inches in diameter and about 6 inches long. In his amazing 45-minute-long video, [glasslinger] shows us how to make a miniature vacuum tube, a half-inch in diameter and only about four inches long.

For those of you who love glass lathes, tiny handheld spot welders and induction heaters, but don’t want your workshop bathed in x-rays, [glasslinger] has also built a  few other vacuum tubes, including a winking cat Nixie tube. This alternate cat’s eye tube was actually sealed with JB Weld, an interesting technique if you’d ever like to make a real home made tube amp.

30 thoughts on “Building A Miniature X-ray Tube

      1. A question of definition. It is definitely a way to drive very fast through life. :-) But could give you a couple of speeding tickets.

        In German “Bleifuß” like “lead foot” means somebody who steps heavily on the gas pedal of the car.

  1. Back when TV sets had tubes, there was one in the HV flyback circuit that was just a massive diode. Those caused the engineers enough trouble struggling to keep all the X-rays IN the tube, finally they turned to making them out of leaded glass. Supposedly “misusing” one of these will still result in detectable X-ray emission.

    They are the bane of the tube collector, absolutely worthless. The dozen or so that I have are to meet the firing squad of the Daisy Red Rider. So, they can probably be had for free at Hamfests.

    1. As far, as I remember, such tubes were just turned in such a way, as to not direct X-rays at viewers. And, with voltage on the range of 25kV, it is just soft Xrays, as in ‘relatively safe’

    2. I actually own eight of those exact flyback rectifier tubes, and once i used one as a xray generator, at three meters and running at 22kv i was redaing 1800 counts a minute on a digital geiger counter, it really freaked me out

  2. Brian, Please add a warning.

    “Ron says:
    May 17, 2012 at 8:01 am
    Seriously HAD? This guy is demonstrating the absolute worst safety I’ve ever seen around x-ray equipment. Sure, awesome craftsmanship, but damn. He be sterile soon. And possibly have further health complications. That glass won’t block the lower-power x-rays. The lower power x-rays are actually the most dangerous to organic matter. Please edit the post to note how extremely dangerous this can be, or even take it down. I hate to be that guy, but damn…”

    “Caleb Kraft says:
    May 17, 2012 at 8:12 am
    Edited to add a warning.”

    1. The X-ray fluorescence was rather dramatic and probably gave him a dramatic radiation exposure in the process. He seems to be old enough that he doesn’t need to worry about fertility (or even cancer, really), so more power to him.

      1. From youtube “I use a survey meter to select a safe place to stand. Also, I don’t operate this stuff for more than a few seconds at a time. Also I rarely operate the x ray tubes at all!”

        1. Survey meters do not trigger on soft Xrays, or show much lower levels than the real ones.
          There was a guy in Russia, who powered an Xray tube and acted the same way.
          But he operated the tube for extended periods, and ignored warnings from others.
          End result – radiation burns on hands, hospital stay and the dose was rather high (if I remember the numbers correctly, if it was full body, he wouldn’t have lived).

          See 5-th post.

        2. also: Survey meters are SENSITIVE – what you’re hearing in the video is probably an exposure level he could have kept up for days before coming close to exceeding his dose limit.

          I’ll admit – when I first saw this video, I thought it was potentially hazardous too… but since then I’ve done a RSO training course at a national nuclear facility. Big point: know why a survey meter =/= dose-rate meter.
          Dose-rate meters are much less sensitive, and usually calibrated for a MUCH higher range – keep in mind that unlike any other hazardous material, sensitive survey meters can have quantum sensitivities that mean they’re probably able to get better than 10% of EVERY single damn atom disintegrating.
          Contrast that to a fictitious “hazardous chemical” sensor that is good for detecting exposure levels of say 0.001 parts per *billion*…. even a typical survey meter is around *a million* times more sensitive than that. Real chemical sensors probably are several thousand to several million times less sensitive than that fictitious 0.001 PPB example, probably having sensitivities in the PPM range.

          The point is that calibration really matters – to know what kind of health risk a source is, you need properly calibrated *dose rate* measurement gear – not a *survey* meter which is sensitive on purpose: It’s for “sniffing out” the location of possibly weak sources, not for figuring out how dangerous they are.

          To make matters worse, most cheaply available survey meters come with a piss-weak “radio active” sample that is perhaps twice background level…. Just a few clicks per second. So that when the new owner finds some rock that makes it scream like this little x-ray tube does, they panic, thinking they’ve found something deadly.

          tl;dr: Just because the survey meter *sounds exciting* doesn’t mean that there’s a significant hazard.

          All this just feeds the urban myth of the super-deadliness of RADIATION!

          1. one CT scan, equating to about one year of background radiation carries about a 1 in 2000 risk of developing a tumour, over and above background risk of cancer. It may surprise you to know that people have actually quantified the ‘deadliness’ of radiation….

  3. I needed a Xray dosimeter just to watch the last part of that video.

    The guy might have mad tube making skills, but lacks even the basics of common sense when dealing with radiation sources.

    And unlike Madam Curie, who died from exposure to her work, but her work moved science forward, this guy is just proving Darwin was right.

  4. Needs more Arduino, then we can call it the “Nukeduino” … :-)

    Seriously guys, X-rays are NOT funny and should be treated as the ionising radiation they are. You wouldn’t mess around with weapons grade plutonium, but even a small tube can do a lot more damage in careless hands.

  5. 10 years of practice to make it look so easy. Worked for a while as an off-hand glass blower, but lamp-work was always beyond me. Sort of the difference between a diesel mechanic and a watch maker.
    Some neat information in general though. Love the home brew pinch welder (I can think of some uses for that) and using an induction heater to flash the getter is (while probably common) is cool.
    If one can get beyond the “You’ll Put Your Eye Out” syndrome, this guy has some neat stuff that could be used for a bunch of non-related hacks.

  6. By the way, the reason that a lot of tubes – even low power tubes – are larger is because then the electron beam flux density is lower, which means the surface of the target isn’t heated/eroded as much, extending the life of the X-ray generator. Also, I believe – though I’m less sure of this part – that larger targets allow for better cooling. Modern X-ray tubes also spin the target so that a larger area is directly heated, so each spot is heated less. The larger target and associated machinery makes the tube and enclosing assembly much larger.

  7. You can make X-rays using: a two stage vacuum pump (even a bad one), piece of LiTaO3 from a defunct PIR sensor or some gas lighters, thin window made of silicon harvested from a broken 8GB uSD memory card, Peltier unit and an aixiz module used as a chamber, with Epoxy and glass feedthrough salvaged from a light bulb then glued where the diode normally goes and the whole thing screwed together, sealed with cyano or LOCA and pumped down.
    Its commercially available with a Be window as “Cool-X” but the snag is that the crystal only lasts about 500 to 1000 cycles.
    I’ve yet to locate them used, probably due to the elf&safety police :-(

  8. Just came by again to see the blab. All I can say is the people that have the most to say seem to have the LEAST amount of ACTUAL experience with the subject! I HAVE THE ACTUAL EXPERIENCE, BOTH IN INDUSTRY HANDLING MASSIVE RADIATION SOURCES AND XRAY EQUIPMENT! I KNOW exactly what I am doing all the time, while these “heresy experts” blab nothing accurate at all. Freedom of speech in action!


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