Day: November 1, 2025

Volumetric Display Takes A Straight Forward (and Backward) Approach

November 1, 2025 by 11 Comments

There’s something delightfully sci-fi about any kind of volumetric display. Sure, you know it’s not really a hologram, and Princess Leia isn’t about to pop out and tell you you’re her only hope, but nothing says “this is the future” like an image floating before you in 3D. [Matthew Lim] has put together an interesting one, using persistence-of-vision and linear motion.

The basic concept is so simple we’re kind of surprised we don’t see it more often. Usually, POV displays use rotary motion: on a fan, a globe, a disk, or even a drone, we’ve seen all sorts of spinning LEDs tricking the brain into thinking there’s an image to be seen. [Matthew’s] is apparently the kind of guy who sticks to the straight-and-narrow, on the other hand, because his POV display uses linear motion.

An ESP32-equipped LED matrix module is bounced up by an ordinary N20 motor that’s equipped with an encoder and driven by a DRV8388. Using an encoder and the motor driver makes sure that the pixels on the LED matrix are synced perfectly to the up-and-down motion, allowing for volumetric effects. This seems like a great technique, since it eliminates the need for slip rings you might have with rotary POV displays. It does of course introduce its own challenges, given that inertia is a thing, but I think we can agree the result speaks for itself.

One interesting design choice is that the display is moved by a simple rack-and-pinion, requiring the motor to reverse 16 times per second. We wonder if a crank wouldn’t be easier on the hardware. Software too, since [matthew] has to calibrate for backlash in the gear train. In any case, the stroke length of 20 mm creates a cubical display since the matrix is itself 20 mm x 20 mm. (That’s just over 3/4″, or about twice the with of a french fry.) In that 20 mm, he can fit eight layers, so not a great resolution on the Z-axis but enough for us to call it “volumetric” for sure. A faster stroke is possible, but it both reduces the height of the display and increases wear on the components, which are mostly 3D printed, after all.

It’s certainly an interesting technique, and the speechless (all subtitles) video is worth watching– at least the first 10 seconds so you can see this thing in action.

Thanks to [carl] for the tip. If a cool project persists in your vision, do please let us know. Continue reading “Volumetric Display Takes A Straight Forward (and Backward) Approach” →

ChatControl Gets Coup-De-Grace

November 1, 2025 by 37 Comments

Possibly the biggest privacy story of the year for Europeans and, by extension the rest of the world, has been ChatControl. Chatcontrol is a European Union proposal backed by Denmark for a mandatory backdoor in all online communications. As always with these things, it was touted as a think-of-the-children solution to online child abuse material, but as many opposed to it have warned, that concealed far more sinister possibilities. For now, it seems we can breathe easily as the Danes are reported to have formally backed away from the proposal after it was roundly condemned by the German government, sending it firmly into the political wilderness.

Hackaday readers are likely vastly more informed on this matter than many of the general public, so you’ll have no need for a primer on the obvious privacy and security concerns of such a move. From our point of view, it also suffered from the obvious flaw of being very unlikely to succeed in its stated aim. Even the most blinkered politician should understand that criminals would simply move their traffic to newly-illegal encrypted forms of communication without government backdoors. Perhaps it speaks volumes that it was the Germans who sounded its death-knell, given that state surveillance on that level is very much within living memory for many of them.

The mood in European hackerspaces has been gloomy of late on the subject, so it’s something of a cause for celebration on the continent. If only other governments on the same side of the Atlantic could understand that intrusive measures in the name of thinking of the children don’t work.

European flags: Šarūnas Burdulis, CC BY-SA 2.0 .