A Digital Replacement For Your Magic Eye

Magic Eye tubes were popular as tuning guides on old-school radio gear. However, the tubes, the 6U5 model in particular, have become rare and remarkably hard to come by of late. When the supply dried up, [Bjørner Sandom] decided to build a digital alternative instead.

The build relies on a small round IPS display, measuring an inch in diameter and with a resolution of 128×115 pixels. One can only presume it’s round but not perfectly so. It was then fitted with a 25mm glass lens in order to give it a richer, deeper look more akin to a real Magic Eye tube. In any case, a STM32F103CBT was selected to drive the display, with the 32-bit ARM processor running at a lovely 72 MHz for fast and smooth updates of the screen.

The screen, controller, and supporting circuitry are all built onto a pair of PCBs and installed in a 3D-printed housing that lives atop a tube base. The idea is that the build is a direct replacement for a real 6U5 tube. The STM32 controller receives the automatic gain control voltage from the radio set it’s installed in, and then drives the screen to behave as a real 6U5 tube would under those conditions.

By virtue of the smart design, smooth updates, and that nifty glass lens, the final product is quite a thing to behold. It really does look quite similar to the genuine article. If you’ve got a beloved old set with a beleagured magic eye, you might find this a project worth replicating. Video after the break.

20 thoughts on “A Digital Replacement For Your Magic Eye

    1. I’ve got a radio with one. They look much better in person than they do in a picture.

      This looks like a decent alternative if you can’t get the real thing, but an LCD screen is not capable of producing the same color as the phosphor in an eye tube. A decent OLED screen would probably get a bit closer though.

      It would look better if there was a metal shield in the middle of the screen and it may be possible to make it look more 3D with some lenses.

      1. I think he meant “IN-33 plasma bar graph” units, which are neon VU meters. That’s at least a bit more special than a row of common neon bulbs. (Although still not ‘magic’ as there’s no ‘shaping’ of the plasma or electron beam.)

  1. I have a working magic eye in my R1155, and one spare in case of the original going.

    But, sooner of later, these will die. The magic eyes had a habit of burning out for unclear reasons. Having a replacement once I run out of spares is valuable.

  2. I scored a Pioneer binaural amp/tuner (2 discrete channels, bridgable) dated 1959 back in the ’80s… Steel Cased, glass lenses, cast knobs, inordinately heavy…

    It used a magic eye tube with green/red responses as a tuning aid, to help fine-tune your reception… IIRC, the green was a very narrow sliver at 12 o’clock position which rarely lit up without a solid VHF-UHF Antenna on the roof and a good deal of manual “fiddling” with the tuner knobs (cannot recall if it was seperate or stacked, but it had a “fine tuning” control in addition to the larger center knob.

    GREAT Sound for its power output, which was damned decent by 1950s standards, but nothing to get worked up over in the 80s, until you plugged it into some beefy speakers… then, it got scary!

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