Ever wanted your own X-ray machine? Of course you have! Many of us were indoctrinated with enticing ads for X-ray specs and if you like to see what’s inside things, what’s better than a machine that looks inside things? [Hyperspace Pirate] agrees, and he shows you the dangers of having your own X-ray machine in the video below.
The project starts with an X-ray tube and a high voltage supply. The tube takes around 70,000 volts which means you need a pretty stout supply, an interesting 3D printed resistor, and some mineral oil.
The output display? A normal camera. You also need an intensifying screen, which is just a screen with phosphor or something similar. He eventually puts everything in lead and reminds you that this is a very dangerous project and you should probably skip it unless you are certain you know how to deal with X-ray dangers.
Overall, looks like a fun project. But if you want real credit, do like [Harry Simmons] and blow your own X-ray tube, too. We see people build similar machines from time to time. You shouldn’t, but if you do, remember to be careful and to tell us about it!
my father had a 1920s copy of ‘the boy electrician’ which showed how to make one. an earlier copy is on project gutenburg. the parts were more available back then. https://www.gutenberg.org/files/63207/63207-h/63207-h.htm#figure-3843
I have a dead trees version. It describes how to make one from scratch (CRT excepted).
It notes that if your skin is becoming red, you shouldn’t use it too much.
If you can pull a good vacuum, you can just use sellotape to make x-rays, no specialist tubes or CRT required. Just unwind the role.
The whole HV supply is just great a giant Cockcroft Walton multiplier and the arc he drew from it just reminded me so much of my time working on televisions and monitors but my god, I was cringing the whole way through at the dots on the pictures where the x-rays were hitting the image sensor, absolutely terrifying.
As they say though, he did it so we don’t have to
the time that i had a dentist x-ray, i pointed it down in the basement and had a mirror underneath the phosphor screen under a 45 degrees angle, so my camera was not in the direct path of the x-rays. even then i had spots, so i concluded the shielding of the tube was insufficient and i stopped immediately after taking just one picture. the x-ray device is now in a military museum as a exhibition piece.
X-ray scattering is a thing. The X-ray generator might be shielded, but everything in the path scatters some of the rays.
A return to modern living for those of us who had our shoe fittings done with the aid of an x-ray machine.
https://clickamericana.com/topics/health-medicine/how-x-ray-shoe-fittings-used-to-really-be-a-thing-years-ago
I’m surprised nobody has tried to recreate them with AI and radars or something.
When I was about 12 years old ( 1967), I did create x-rays in my bedroom. They were strong enough to expose some film with my hand in front. But very poorly . As there was no focusing mech. ( a scatter gun of black spots with a hand print). I guess I was luck to have normal kids.
[Hyperspace Pirate] got some things wrong, but he got enough right for it to work and not kill himself doing it. Kudos.
What he really missed, though, is the importance of x-ray filtration: He’s not using any (except the glass wall of the tube), and he really should.
The x-ray source produces a broad spectrum of X ray photon energies, biased strongly toward the lower energies. Those lower energies you really don’t want: They get absorbed first, dumping all their dose in the first millimeter or two of the object (or your skin). They don’t penetrate the object, don’t contribute to the image except by making it nonlinear in response (brightness:object density).
Worse: even if the photons make it through, they don’t have enough energy to light up the fluorescent screen much. Even worse: The huge number that do hit the screen unimpeded by any object make up in numbers what they lack in efficacy and light it up brightly anyway, swamping the camera with too much scattered light and way too much dynamic range.
So you fix that by putting a sheet metal filter in front of the x-ray source. For 70 kV potential, 10 mm of aluminum is good, or 1 mm of copper is better (produces lower scatter). You end up compressing the (ridiculous) dynamic range and linearizing the image, and maybe (literally) save your skin.
Yep. The lack of filtering (hardening) plates made this all very unnerving to watch for me. Especially the bit where he was not getting any xrays through because the PSU sagged. I don’t know what currents he was running on the anode but from my limited understanding this must have been an awefully large dose of 100% absorbed soft xrays
The classic Scientific American Book of Projects for the Amateur Scientist, published 1960, includes instructions for an X-ray machine based on a (then still fairly common) model 01A vacuum tube.
The CD of “The Amateur Scientist” which has all of those projects is still available from Surplus Shed and elsewhere. If memory serves, the step-up transformer was to be made with a primary of a few turns of 1/4″ copper tubing. The secondary was something like 5000 turns of much finer wire.
One day I plan to do this but with a cheap dental x-ray unit off aliexpress and the digital sensor plates. While I can’t vouch for the quality of such a device and would still need to take all possible precautions, it’s still going to be a lot better than rolling the x-ray source myself and almost certainly includes the appropriate filtering as mentioned elsewhere.
I heard that some thermionic vacuum tubes can give off xrays if the anode-cathode voltages are greatly exceeded. was never able to test this.
They can, but then the trouble is that the X-rays aren’t what you’d call directional, as they are in a purpose-built X-ray tube.
The X-ray tube is adorably sized!
It’s rare that I say this, but the comments below the video are worth reading if you’re thinking about making something similar. Especially regarding his lack of hardening plates (basically aluminum or copper, to absorb the lower-energy X-rays). IMO, it would have behooved him (and informed us) to have a film badge, so he actually knew the dosage he received.