Author: Lewin Day

3561 Articles

Random Number Generator Uses Camera Noise

February 25, 2026 by 17 Comments

Random numbers are very important to us in this computer age, being used for all sorts of security and cryptographic tasks. [Theory to Thing] recently built a device to generate random numbers using nothing more complicated than simple camera noise.

The heart of the build is an ESP32 microcontroller, which [Theory to Thing] first paired with a temperature sensor as a source of randomness. However, it was quickly obvious that a thermocouple in a cup of tea wasn’t going to produce nice, jittery, noisy data that would make for good random numbers. Then, inspiration struck, when looking at vision from a camera with the lens cap on. Particularly at higher temperatures, speckles of noise were visible in the blackness—thermal noise, which was just what the doctor ordered.

Thus, the ESP32 was hooked up to an OV3660 camera, which was then covered up with a piece of black electrical tape. By looking at the least significant bits of the pixels in the image, it was possible to pick up noise when the camera should have been reporting all black pixels. [Theory to Thing] then had the ESP32 collate the noisy data and report it via a web app that offers up randomly-generated answers to yes-or-no questions.

[Theory to Thing] offers up a basic statistical exploration of bias in the system, and shows how it can be mitigated to some degree, but we’d love a deeper dive into the maths to truly quantify how good this system is when it comes to randomness. We’ve featured deep dives on the topic before.

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Building An Interactive Climbing Wall

February 25, 2026 by 6 Comments

Climbing is a cool sport. With that said, like everything, it’s even better if you integrate lots of glowing colorful LEDs. To that end, [Superbender] worked up this fun climbing wall that features interactive lighting built right in.

Structurally, there’s nothing too wild going on here. It’s a wood-framed climbing structure that stands 10 meters long and 2.5 meters high, and can be covered in lots of climbing holds. It’s the electronic side of things where it gets fun. An Arduino Due is installed to run the show, hooked up with a small TFT display and some buttons for control. It’s then hooked up to control a whole bunch of LEDs and some buttons which are scattered all across the wall. It’s also paired with an Arduino Nano which runs sound feedback, and a 433 MHz remote for controlling the system at a distance.

[Superbender] uses the lighting for fun interactive games. One example is called Hot Lava, where after each climbing pass, more holds are forbidden until you can’t make the run anymore. Chase the Blues is another fun game, where you have to climb towards a given hold, at which point it moves and you have to scamper to the next one.

We’ve featured similar projects before from other inventive climbers.

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Modded Lightbox Makes For Attractive LED Matrix Display

February 24, 2026 by 5 Comments

If you’ve been to a wedding or a downtown coffee shop in the last 10 years, you’ve probably seen those little lightboxes that are so popular these days. They consist of letters placed on a plastic frame in front of a dim white light, and they became twee about five minutes after your hipster friend first got one. However, they can also make a neat basis for an LED display, as [Folkert van Heusden] demonstrates. 

The build is straightforward enough, using daisy chains of 32×8 LED matrix modules, two each for the three rows of the lightbox. This provides for a 24 character textual display, or a total display resolution of 64 x 24 pixels. An ESP8266 is used to command the matrixes, which are run by MAX7219 display controllers. Thanks to the microcontroller’s onboard wireless hardware, the display can be addressed in a number of ways, such as using the LedFX DDP protocol or [Folkert’s] Pixel Yeeter python library. Files are on GitHub for the curious.

Quite a few of these exist out in the wild — [Folkert] has built a variety of modded lightboxes over the years with varying internals. The benefit of the lightbox is that it effectively acts as a handy housing for LED matrixes and supporting electronics, while also providing a neat diffuser effect. The lightboxes are also readily wall mountable and generally look more like an intentional piece of signage than most things we might homebrew in the lab.

We’ve featured similar-looking builds before, like this public transit display that was hacked for custom use. If you’re building your own public information boards or other nifty LED displays, don’t hesitate to notify the tipsline!

How Safe Are Old Airbags, Anyway?

February 23, 2026 by 56 Comments

Automotive airbags are key safety devices that aim to reduce injuries and mortality in the event of motor vehicle accidents. These rapidly-inflating cushions act to soften the blow of an impact, catching occupants of the vehicle and preventing them from hitting hard parts of the vehicle’s interior.

Airbags are rigorously tested to perform as faultlessly as possible under all conditions. However, no system is perfect, and every automotive component has an expected service life. The question is—how old is too old when it comes to airbags? The answer is not exactly straightforward.
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Recreating Mega Man’s Mega Buster

February 22, 2026 by 9 Comments

Mega Man is a popular video game character who is perhaps most notable for having a sort of lasery-type blaster for an arm. A real hand cannon, if you will. It’s officially called the Mega Buster, and [Arnov Sharma] recently recreated it for cosplay purposes.

Key to any good cosplay build is getting the visuals right, and [Arnov] achieved that well. The Mega Buster was first recreated in Fusion 360, scaled to an appropriate size to fit [Arnov]’s arm. It was 3D printed in several sections, with the body including a grab handle and fire button inside, and the side panel and blaster nozzle having provision for installing LEDs. The former is the blaster’s “power meter” which shows how many shots it has left until it runs out of energy, with the blaster able to fire six times before needing to cooldown. A Raspberry Pi Pico controls the LEDs and provides sound effects with the aid of a PAM8403 class D amplifier module and a small speaker.

The 3D files are available on Instructables for the curious. Perhaps by virtue of its arm-mounted nature, this build reminds us of the venerable Pip Boy from Fallout, of which we’ve seen many grand recreations before. Video after the break.

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Exclamation Point Indicates Worthy Notifications

February 22, 2026 by 1 Comment

As far as punctuation goes, the exclamation mark is perhaps the most eye-catching of the bunch. That’s why [Conrad Farnsworth] thought this form would be perfect for his Home Assistant notifier build. 

The key to this build is the large bi-color printed housing in the shape of an exclamation mark. It makes for an attractive wall-hanging, but it also perfectly serves the purpose [Conrad] had in mind. Inside the enclosure is an ESP32, hooked up to a string of 16×8 LED matrixes which are commanded over I2C. These sit behind a white panel in the enclosure to nicely diffuse the light and make their output more readable. The ESP32 displays notifications on the LEDs that are fed from Home Assistant, such as when the mailbox sensor is triggered or if a vehicle is detected in the driveway. There’s also a bell on the unit to provide audible notifications, which us dinged with a solenoid fired via a 2N2222 transistor switching a 12 volt supply from a boost converter.

It’s a neat build that fits nicely into [Conrad]’s daily life and appears to have some genuine utility. If you’re looking for other ways to neatly display notifications where you can see them, you might consider whipping yourself up a smart mirror.

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Cheap Writing Deck Eschews Distractions

February 20, 2026 by 13 Comments

A modern computer can be a great productivity tool. It can also be a great source of distractions. To solve that issue, [Quackieduckie] built the e-typer—a device for writing without distraction.

[Quackieduckie] refers to the device as a “low-cost e-ink typewriter” which lays out the basic mode of operation. It consists of a 4.2 inch e-ink screen, combined with an Orange Pi Zero 2W running the Armbian operating system. It’s set up to boot straight into a document editor so there’s no messing around with other software that could get in the way of productivity. The components are all wrapped up in a tidy 3D printed housing, which includes a foldable stand so you can prop the screen up wherever you happen to be working. [Quackieduckie] built the device to work with any USB-C keyboard, probably figuring that those eager to maximize productivity will already have the typing device of their dreams on hand. Code for the project is available on GitHub for those eager to replicate the build.

We’ve featured similar builds in the past, often referred to as “writing decks.” They’re becoming increasingly popular as people look for distraction-free, ad-free tech experiences. A great example is this clamshell design with an integrated keyboard. If you’re building your own productivity aids in your home lab, don’t hesitate to notify the tipsline!