If you’ve got a decent CRT monitor, you can usually adjust the settings to make sure the image scans nicely across the whole display. But what if you could rotate the whole image itself? [Jeri Ellsworth] has shown us how to achieve this with an amusing mechanical hack.

The trick behind this is simple. On a standard CRT, the deflection yoke uses magnetic coils to steer the electron beam in the X and Y axes, spraying electrons at the phosphors as needed. To rotate the display as a whole, you could do some complicated maths and change how you drive the coils and steer the electron beams… or you could just rotate the entire yoke instead. [Jeri] achieves this by putting the whole deflection yoke on a custom slip ring assembly. This allows it to receive power and signal as it rotates around the neck of the tube, driven by a stepper motor.

Amusingly, [Jeri] even found a super nifty way to drive the stepper. There are no microcontrollers or fancy driver logic here—instead, the quadrature output from a rotary encoder outputs a perfectly legible pulse train which can drive the stepper as needed. [Jeri] notes this provides a nicely instantaneous response. There’s still work to be done, too. The project is due to get a 3D-printed housing, a homing system, and some improvements to the DIY slip ring setup.

If [Jeri’s] name sounds familiar, that’s because she’s built many a grand project over the years. You might have seen her work on the C64 DTV or the breadbin keytar.

I have big plans for spinny CRT

— Jeri Ellsworth (@jeriellsworth.bsky.social) 2026-01-05T10:42:52.953Z

[Thanks to Neonsystem95 for the tip!]

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