This Homebrew X-ray Machine Sees Right Through You — and Most Other Things

Pseudonymous self-described builder of things "Hyperspace Pirate" has decided the latest thing to build should be a homebrew X-ray machine — because, with apologies to the lessons of Marie Curie, what could go wrong?

"I've had this X-ray tube sitting on my shelf for three or four years," Pirate explains of the project's origin, "so I figured it was time I finally did something with it. The inner workings of an X-ray are actually surprisingly simple: the rays are generated by an X-ray tube, which is just a special type of vacuum tube. Heater current comes into the cathode to get it white hot and boil off electrons, just like in any other vacuum tube — but in an X-ray tube the anode is at tens of thousands of volts, so when that electron pops free from the cathode it accelerates like a bat out of hell toward that high voltage anode. The electrons hit the anode so fast that some of them release a super high energy photon, which is where you get your X-rays from."

Theory is one thing, but Pirate was after something more hands-on — building an X-ray machine to make use of the tube that had otherwise been serving as unusual office decor. The final design uses a 10-stage voltage multiplier built using pairs of 20kV 1nF capacitors in series and 20kV 100mA diodes in series, putting out nearly 120kVDC unloaded and 50-70kVDC under load.

A high-voltage transformer is created using two flyback transformer cores, with four turns on the primary and 750 on the secondary, turning 24V into around 12kV unloaded — and both the transformer and the X-ray tube are submerged in mineral oil to keep them cooled. Finally, the cathode heater is powered by an adjustable DC-DC buck converter, with 2.3A delivering the highest quality image. "This number is highly dependent on the power of the anode power supply, and a more powerful supply would be able to provide a picture at a higher cathode current without pulling down the voltage excessively."

Now, playing around with X-rays at home is perhaps not the safest thing in the world, but Pirate has at least taken a few precautions: a remote control allows the operator to stand well clear of the device before triggering X-ray generation, a timer limits its operation to less than a second, and measurements taken with a dosimeter show radiation levels of ~0.5-1.0µSv/h averaged over a one minute period during exposure, falling to almost nothing at around 32 feet from the device.

Rather than using photographic film as the target, Pirate opted to put a smartphone in the beam path — capturing the X-rays as they pass through, are reflected from, or absorbed by the materials placed in the beam, ranging from electronics to a fortunately already-deceased squirrel. The resulting images are impressive, though fellow YouTuber "thethoughtemporium" points out in the comments that the phone is likely being damaged in the process — and that better results can be achieved using a DSLR camera and a mirror to keep the camera out of the beam path.

The full video is embedded above and on the Hyperspace Pirate YouTube channel; a schematic has been uploaded to Google Drive, though Pirate advises that you "don't generate ionizing radiation ['cos] it's bad and stuff."