On no planet is making your own X-ray tube a good idea. But that doesn’t mean we’re not going to talk about it, because it’s pretty darn cool.
And when we say making an X-ray tube, we mean it — [atominik] worked from raw materials, like glass test tubes, tungsten welding electrodes, and bits of scrap metal, to make this dangerously delightful tube. His tool setup was minimalistic as well– where we might expect to see a glassblower’s lathe like the ones used by [Dalibor Farny] to make his custom Nixie tubes, [atominik] only had a small oxy-propane hand torch to work with. The only other specialized tools, besides the obvious vacuum pump, was a homebrew spot welder, which was used to bond metal components to the tungsten wires used for the glass-to-metal seals.
Although [atominik] made several versions, the best tube is a hot cathode design, with a thoriated tungsten cathode inside a copper focusing cup. Across from that is the anode, a copper slug target with an angled face to direct the X-rays perpendicular to the long axis of the tube. He also included a titanium electrode to create a getter to scavenge oxygen and nitrogen and improve the vacuum inside the tube. All in all, it looks pretty similar to a commercial dental X-ray tube.
The demonstration in the video below is both convincing and terrifying. He doesn’t mention the voltage he’s using across the anode, but from the cracking sound we’d guess somewhere around 25- to 30 kilovolts. The tube really gets his Geiger counter clicking.
Here’s hoping [atominik] is taking the proper precautions during these experiments, and that you do too if you decide to replicate this. You’ll also probably want to check out our look at the engineering inside commercial medical X-ray tubes.
One of my favorite books as a kid was the collection of Scientific American’s Amateur Scientists columns. Two of my favorite projects I never made were the particle accelerator and the X-ray tube. Thank goodness I wasn’t adept enough to pull either off at that time! I would probably not be here or, at least, my son would not be here!
“The Amateur Scientist” by C.L. Strong. There’s a copy on the shelf behind me in my office.
You can order a copy from Amazon, it’s truly an amazing book.
Also, you can find it online for free at the Internet Archive:
https://archive.org/details/Projects_for_the_Amateur_Scientist_Scientific_American
And it has an xray machine for $20.
I had a subscription to Scientific American for two years starting about 1969. Almost all was beyond me. The projects seemed more advanced than those in the book.
I morphed into hobby electronic magazines in Jan 1971, everything beyond me too, but I stuck with it and got better.
Scientific American has dumbed down a lot in recent times.
One issue in the 1970’s had a big article on making the equipment for a LASER show, including how to make a mercury vapor LASER from scratch.
Truly a great book! I also have the CD:
https://archive.org/download/Scientific_American_The_Amateur_Scientist_Tinkers_Guild_2000
“dangerously delightful tube” or “delightfully dangerous tube”? :D
You’re not in danger of being overly delighted which means it’s the later.
I suppose a homemade X-ray could de-light its builder if they are not careful.
B^)
“Bremsstrahlung radiation? At this time of year, at this time of day, in this part of the country, entirely localised to your work bench?”
Bremen Strasse what?
B^)
Bremerhavencontainerhafen
Great Work! Especially the part about Titanium-Oxidation to increase the vacuum without a turbo-pump!
But ;) https://www.youtube.com/watch?v=gmOTpIVxji8
And I would recommend some lead foil – hint: it is a material sometimes used by roofers cause you can bend it easily around complicated real roof tiles patterns to stop water from coming in.
The first paragraph hits an excellent balance between spirit of experimentation and basic safety warning and ethical reporting. Thank you, HaD.
I call BS. How does that sentence have a “basic safety warning”? It says “On no planet is… a good idea…”. That’s not an “excellent balance” between experimenting and expressing safety concerns- it insists no-one should do it. It doesn’t encourage experimentation; in fact, it actively insists on no experimentation. I’m not judging the writing, just your comment praising it for it’s even-handedness. “Ethical reporting”? That’s nonsense- we don’t need journalists to make value judgements, or to decide if a project’s risk is too high for the readers: if there’s a safety concern, they can report on actual incidents or concerns, rather than acquiescing to the mob of namby-pamby readers who’re terrified someone will slightly hurt themselves. Just saying “don’t do this” is the lazy way out. Again, not judging the piece, only saying you should put on your apron and goggles and calm down, sir.
Ah yes, your xray goggles. I saw an ad for those once.
““Ethical reporting”? That’s nonsense- we don’t need journalists to make value judgements, or to decide if a project’s risk is too high for the reader”
Well, good job that’s not what has happened then, is it?
Though of course, the moment someone mentions that terrible dreadful scary word ‘ethics’, the usual subjects emerge from the woodwork to yell and scream about imaginary boogeymen coming to do terrible awful things of an unspecified and nebulous nature (as if telling “running an active unshielded X-ray emitter on your workbench is not a good idea” is somehow a horrible grievance that actively offends everyone).
You ethics dweebs make my skin crawl. Why are you like this?
Virtue signaling is all the rage these days.
Never publicly let a sucker keep his money!
So, what’s the roadmap between what’s been done here and building new CRT displays? Any way to get there from here?
It’s a looooong way from a new CRT. Unless you mean one of those very simple static deflection ones from the late 1800’s. Braun made those with pretty simple tubes. You could make a very crude oscilloscope.
Or Philo Farnsworth’s display tube that was able to show a straight line imaged with his image dissector tube. Crude but the first demonstration of all electronic television.
Not quite: http://www.sparkbangbuzz.com/crt/crt6.htm
any way? Trial and error, lots if it. Even a monochrome CRT for picture/video is surprisingly hard. Especially if you want to make reasonably sized.
Orthogonal, CRT’s are steered electron beam emitters, any X-rays are an undesired byproduct.