This (Pseudo) Random Number Generator Does It With Neon

May 12, 2026 by Donald Papp No comments

The quest for true randomness has roots in cryptography and is a rabbit hole that gets surprisingly deep with alarmingly rapidity. Still, the generation of random-enough numbers is a popular hacker project. Part of the appeal is the way these devices strive to incorporate physical phenomena, and in [Joshua Coleman]’s case, his Neon Entropy (Pseudo) Random Number Generator uses a trio of vintage neon lamps.

Neon lamps discharge at rates that vary unpredictably. They’re also pretty to look at.

[Joshua] chose neon lamps in part because the discharge rate of an energized lamp is a variable, physical process that makes a good source of entropy. They also have an attractive visual appeal that fits the concept [Joshua] had in mind. Unlike random number generators that kick off by measuring radiation or some other imperceptible thing, it’s possible — at least in a sense — to see this one working.

The small variations in the three neon lamps are measured optically by three TEPT4400 ambient light sensors (isolated from the neon lamps themselves) and turned into analog signals. A Raspberry Pi Pico W reads these signals, then uses them in a process that culminates in SHA-256 64-bit values that can be used as random seeds.

There’s also a web dashboard that shows everything live, furthering the “watch it work” concept [Joshua] is aiming for. The video below shows the project in action if you want to see how the sausage gets made.

Earlier we mentioned how random number generators are popular projects among hackers, and here are a few selected ones. Don’t miss the stylish glow and slick enclosure of this Nixie tube RNG, or the lava lamp RNG which is in fact not a gimmick. And while it is commonly understood that meaningful randomness must come from outside a digital chip, uninitialized internal volatile RAM — if accessed correctly — can be a remarkably good source of entropy.

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Want Driving Simulator Feedback? Make The Robot Do It

May 11, 2026 by Donald Papp 24 Comments

Humanoid robots are a thing now, and here’s an interesting research project that explores using one as a form of haptic media. Specifically, using a humanoid robot to move a chair while one plays a VR driving simulator.

Here’s how it works: a Unitree G1 robot sits behind a player’s chair and grasps it with its hands. Spherical markers on the chair help the robot’s depth camera know the chair’s position, and real-time G-force signals fed from the simulator (Assetto Corsa, running on PC) tell the robot how much and in what direction to shift the chair to match in-simulator events.

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How To Avoid Failed Screw Holes In 3D Printed Parts

May 7, 2026 by Donald Papp 21 Comments

Screws are useful fasteners for 3D prints, but the effectiveness of a screw (not to mention the ease or hassle of insertion) depends on the hole itself. This comprehensive guide on how to design screw holes in 3D printed parts takes guesswork out by providing reference tables as well as useful general tips.

The guide provides handy tables saying exactly how big to design a hole depending on screw type, material (PLA, PETG, or high-flow PETG) and whether the hole is printed in a vertical or horizontal orientation. This takes the guesswork out of screw hole design.

There’s no reason to guess the right size of hole for a screw, just refer to some handy tables.

The reason for different numbers is because multiple (but predictable) variables affect a 3D-printed hole’s final dimensions. Shrinkage, filament properties, and printing orientation can all measurably affect small features like screw holes; accounting for these is the difference between a good fit, and cracking or stripping.

In addition to the tables, there are loads of other useful tips. Designing lead-ins makes screws easier to insert and engage, and while increasing walls is an easy way to add strength it’s also possible to use 3D-printed microfeatures which are more resistant to distortion and don’t depend on slicer settings. There’s even suggested torque amounts for different screw and material types.

Sure, the most reliable way to get a hole of a known size is to drill it out yourself. But that’s an extra step, and drill bits aren’t always at hand in the desired sizes. The guide shows that it is entirely possible to print an ideal screw hole by taking a few variables into account.

If your design calls for screws, be sure to check it out and see if there’s anything you can use in your own designs.

How To Better Enjoy VR On Linux

May 6, 2026 by Donald Papp 18 Comments

Linux folks are used to having to roll many of their own solutions, and better Linux desktop usability is a goal of the WayVR project, which aims to provide desktop control and app launching from within a VR session.

VR applications can already stream from Linux to standalone headsets with projects like WiVRn (check out this WiVRn setup guide for a fuller understanding), but what WayVR does is let one launch programs and access desktop screens within VR. Put another way, instead of the headset being limited to acting as a pseudo-monitor that only receives the output of an already-running VR application, the headset and controllers can now be used to interact with one’s computer as if one were physically sitting at it. Controls and user interface are highly flexible and help users to do anything they need — including clicking, typing, and launching applications. It’s a considerable step forward for convenience and general usability.

Naturally, when it comes to using a computer from within VR there is plenty of unexplored territory regarding user interfaces. It’s fertile ground for experimentation in everything from DIY headsets to ways to input text without a keyboard, so if you enjoy working on the frontiers of such things, it’s a good scene to dive into.

The Threadless Ball Screw Never Took Off, But Don’t Write It Off

April 2, 2026 by Donald Papp 37 Comments

If you’ve never heard of the threadless ball screw, which was invented over sixty years ago, [Angus] of Maker’s Muse has a video demonstrating the whole thing, covering its history and showcasing both its strengths and weaknesses. If you like seeing mechanical assemblies in action, give it a watch.

The device — consisting of little more than a smooth rod and three angled ball bearings — is a way to turn rotational motion into linear motion. Not a single belt, thread, or complex mechanical assembly in sight. While a simple nut on a threaded rod can turn rotation into linear motion, those come with their own issues. The threadless ball screw was one effort at finding a better way.

While it lacks precision, the threadless ball screw nevertheless offers quiet and smooth motion with adjustable tension in a very DIY-friendly design.

Threadless ball screws never really took off, although they were given some consideration for use in 3D printers back in the RepRap days. Today one can purchase quality CNC components without leaving one’s web browser, but back in the early 2000s things like lead screws and ball screws were rather more specialized, less accessible, and more expensive than they are today. RepRap folks had to make their own solutions. But while the threadless ball screw is a very DIY-friendly design, it was ultimately lacking in performance.

The main problem is they’re just not precise enough for anything like CNC work. [Angus] does some back-and-forth tests with a 3D printed unit that shows serious drift after only a few minutes. Now, he knows perfectly well that his 3D-printed test unit is far from ideal, but the rapidity at which it drifted was still a surprise. Making a carriage with two threadless ball screws — one at each end — performed a lot better, but was ultimately still flawed.

It’s not all bad. There’s zero backlash. They are mechanically simple, remarkably smooth, and utterly quiet. Also, [Angus] discovered that the maximum force this setup can be made to apply is surprisingly significant, and is directly related to the tension on the bearings. That means one can trivially adjust how easily the carriage slips (or doesn’t) just by tightening or loosening the screw holding each bearing.

Sure, they’re not precise. But maybe you don’t need precision. Maybe you just need to move something back and forth in a strong & silent sort of way that can still slip gracefully (and quietly) if something goes awry, like bottoming out an axis. 3D printing makes it pretty easy to whip one up, so maybe there’s still a place for the threadless ball screw.

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Pixel Camera Puts Lo-Fi Images In The Palm Of Your Hand

April 2, 2026 by Donald Papp 1 Comment

Some things have an undeniable appeal, and lo-fi, pixelated Game Boy-camera-like images are one of them. In service of this, [Raul Zanardo] created his handheld pixel camera that goes the extra mile. It implements slick real-time pixel art filters and a number of other useful features.

A live preview with real-time filters makes capturing just the right image easy.

For hardware, [Raul] uses a LilyGo T-Display S3 Pro which is an ESP32-based development board, camera, and color touchscreen display in a handheld form factor that vaguely resembles a chunky smartphone. The only change is swapping the stock camera for an OV3660-based camera module. It’s a drop-in replacement, but necessary because some of the features and settings his software uses are not available on the stock camera.

The camera captures 240 x 176 images, but the really neat part is the real-time filter pipeline. There are many configurable choices to play with, including pixelation, dithering, edge detection, CRT scanline effect, and color palette presets. Captures are saved to a local micro SD card and there’s all kinds of handy features like a photo gallery that takes full advantage of the color touchscreen. There’s also USB Mass Storage functionality, so downloading photos is as simple as plugging in a USB cable.

The Game Boy camera’s charming lo-fi imagery has inspired many pixel-camera projects, and this one makes great use of an inexpensive handheld development board and includes truly useful features.

Do you have your own pixel-art inspired camera project? Hit up our tips line and tell us all about it!

Watch An Electro-Permanent Magnet In Action

April 1, 2026 by Donald Papp 12 Comments

Electro-permanent magnets (EPMs) are pretty nifty concepts, and if you aren’t familiar with them, they are permanent magnets with the ability to be electrically switched on or off. Unlike an electromagnet — which maintains a magnetic field only while power is applied — an EPM can remain “on” even when power is removed. Want to see one work? There’s a video embedded below that shows one off, but if you’d like to know how they work, we have you covered.

Inside are two types of magnet, one of which is permanent and the other being a semi-hard magnet paired with an electromagnetic coil. A semi-hard magnet’s flux can be changed by exposing it to a strong enough magnetic field, and that’s the key to making it work.

When both magnets work together, the EPM is “on” and acts like a permanent magnet. To turn the EPM off, the polarity of the semi-hard magnet is flipped with a short and powerful electromagnetic pulse, after which the two magnets oppose one another and more or less cancel each other out. So rather than generating a magnetic field, an EPM more accurately reconfigures it.

As intriguing as EPMs are, we haven’t really seen one properly in action until it was brought to our attention that [Dave Jones] of EEVblog tried one out last year. He received a Zubax FluxGrip EPM, which is intended for drone and robotic applications and can hold up to 25 kg. Watch [Dave] fire it up in the video (link is cued up to the 7:30 mark), it’s pretty interesting to see one of these actually work.

EPMs are not prohibitively expensive but they are not exactly cheap, either. But if a switchable magnet sounds up your alley and you can’t afford an EPM, consider an alternative “switchable” magnet design that works by momentarily canceling out a permanent magnet with a paired electromagnet. Unlike an EPM, it’s not a permanent switch but it would be enough to drop a payload.

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