Building Beautiful LED Lanterns With Black LED Acrylic

December 27, 2025 by 1 Comment

[Geeksmithing] and [When Geeks Craft] recently came together for a glowing collaboration. They wanted to build ever more attractive lanterns for a local parade event. They recently discovered a fantastic material that can really improve the look of whatever project you might be building with LEDs.

The material is commonly referred to as “Black LED Acrylic” or similar. In this case, it was sourced from TAP Plastics, though you can source similar acrylic from other vendors, too. From first glance, it looks like any other piece of black acrylic plastic. However, shine an LED through it, and it will be beautifully diffused and smoothed out to wonderful visual effect. A simple test of a 3×3 array of LEDs behind a 3D-printed grid shows how good this can look. It almost entirely eliminates hot spots, and the result looks like a display built out of juicy glowing cubes. The duo used this material to produce giant pixel art lanterns for their local parade. We only get a glimpse at the final build, but it appears giant Pacman and Blinky totems are on the way.

If you’ve been struggling to find a good way to diffuse the light from LEDs, you might want to give this stuff a try. Alternatively, you might explore some other methods we’ve looked at before, and don’t discount ping pong balls, either.

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a torn-up printer with a very long image of different frames

Playing DOOM On A Receipt Printer

December 27, 2025 by 6 Comments

Gaming is a wonderful thing. Unfortunately for many of us, work takes up our valuable time, which should be allocated to our gaming. What if there was a better way? Well, printers can print an image quickly, and receipt printers can print a lot of images. This sounds like an effective display for DOOM in a pinch. [Bringus Studios] managed to find such a printer and got the classic shooter running.

Getting the printer’s attached computer, which was only designed for printing the cost of your chicken sandwich, to run Half-Life was far from easy. [Bringus] struggled through the process of swapping operating systems from Windows 7 to Linux just to return to Windows 7 after a painful process of maintaining compatibility between 32 and 64 bit software. Driver issues followed through the entire process just to get anything running at all.

But we can’t play DOOM while at work on a normal screen. The printer MUST display our glorious 480p gameplay. To achieve such a workflow, [Bringus] implemented a script to print out a frame of the display, allowing for “visible gameplay”. Along with some heat issues from the nature of thermal receipts, eventually the printer displayed the glory of DOOM.

Playing games on a thermal printer might be one of the weirdest things you’ve seen today, but what if we could reverse the script a bit and create a printer from something else? Here at Hackaday, we have exactly the thing for you: a printer made from a vintage typewriter!

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Active Ideal Full Bridge Rectifier Using TEA2208T

December 27, 2025 by 12 Comments

Everyone loves a full-wave bridge rectifier, but there’s no denying that they aren’t 100% efficient due to the diode voltage drop. Which isn’t to say that with some effort we cannot create an ideal bridge rectifier using active components, as demonstrated by [Mousa] with an active bridge circuit. This uses the NXP TEA2208T active bridge rectifier controller, along with the requisite four MOSFETs.

Comparing a diode bridge rectifier with an active bridge rectifier. (Credit: Mousa, YouTube)
Comparing a diode bridge rectifier with an active bridge rectifier. (Credit: Mousa, YouTube)

Taking the circuit from the datasheet, a PCB was created featuring four FDD8N50NZ MOSFETs in addition to the controller IC. These were then compared to a diode-based bridge rectifier, showing the imperfections with the latter when analyzing the output using an oscilloscope.

As expected, the active rectifier’s output was also one volt higher than the diode bridge rectifier, which is another small boost to overall efficiency. According to NXP’s product page, there’s about a 1.4% efficiency gain at 90 VAC, with the chip being promoted for high-efficiency operations. When you consider that many designs like computer PSUs feature one or more diode bridge rectifiers often strapped to heatsinks, the appeal becomes apparent. As for [Mousa], he put this particular board in his laboratory PSU instead of the diode bridge rectifier, because why not.

Perhaps the biggest impediment to using an active rectifier is the cost, with the TEA2208T coming in at $4 on DigiKey for a quantity of 100, in addition to the MOSFETs, PCB, etc. If power efficiency isn’t the goal, then some wasted power and an aluminium heatsink is definitely cheaper.

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Print Your Next LED Bezel

December 27, 2025 by 3 Comments

LED bezels (also known as LED panel-mount holders) are great, so how about 3D printing the next ones you need? Sure, they’re inexpensive to purchase and not exactly uncommon. But we all know that when working on a project, one doesn’t always have everything one might need right at hand. At times like that, 3D printing is like a superpower.

Printing a part you find yourself short of can be a lifesaver.

[firstgizmo]’s design is made with 3D printing in mind, and most printers should be able to handle making them. Need something a little different? You’re in luck because the STEP files are provided (something we love to see), which means modifications are just a matter of opening them in your favorite CAD program.

There’s not even any need to export to an STL after making tweaks, because STEP support in slicer programs is now quite common, ever since PrusaSlicer opened that door a few years ago.

Not using 5 mm LEDs, and need some other size? No problem, [firstgizmo] also has 3 mm, 8 mm, and 10 mm versions so that it’s easy to mount those LEDs on a panel. Combined with a tool that turns SVG files into multi-color 3D models, one can even make some panels complete with color and lettering to go with those LEDs. That might be just what’s needed to bring that midnight project to the next level.

Building A Wall-Mounted Sound Visualizer

December 27, 2025 by 5 Comments

Visualizers used to be very much in vogue, something you’d gasp in at amazement when you’d fire up Winamp or Windows Media Player. They’re largely absent from our modern lives, but [Arnov Sharma] is bringing them back. After all, who doesn’t want a cool visualizer hanging on the wall in their living room?

The build is based around the Raspberry Pi Pico 2. It’s paired with a small microphone hooked up to a MAX9814 chip, which amplifies the signal and offers automatic gain control to boot. This is a particularly useful feature, which allows the microphone to pick up very soft and very loud sounds without the output clipping. The Pi Pico 2 picks up the signals from the mic, and then displays the waveforms on a 64 x 32 HUB75 RGB matrix. It’s a typical scope-type display, which allows one to visualize the sound waves quite easily. [Arnov] demonstrates this by playing tones on a guitar, and it’s easy to see the corresponding waveforms playing out on the LED screen.

It’s a fun project, and it’s wrapped up in a slick 3D printed housing. This turns the visualizer into a nice responsive piece of wall art that would suit any hacker’s decor. We’ve featured some other great visualizers before, too. Continue reading “Building A Wall-Mounted Sound Visualizer” →

Drunken EBay Purchase Becomes Motorized, Speaking Dalek

December 26, 2025 by 9 Comments

Not every impulsive purchase on eBay leads to possession of a wooden Dalek, but when a friend did exactly that, [Tony Goacher] did his part to turn ‘Dalek Bob’ into a motorized and remote-controlled unit of impressive stature.

Fitting wheels to shafts and motors to a frame can be a bit tricky when none were made with the other in mind.

The purchased Dalek is made of wood and, with the help of two bolts, is of sufficient size to trap a human inside. There’s a bench of sorts upon which the captive can sit, and with some effort, shuffle the surrounding frame awkwardly about. The scale of the Dalek is impressive, but it was clear the effect of human-powered locomotion was lacking. The solution was to install wheelchair motors, tires, and an ESP32-based remote control.

Quite a lot of work went into mounting the motors and wheels, and the challenges will be familiar to anyone who has done hobby robotics. One can choose ideal motors and wheels, but making them fit one another can be an entirely different story. Shafts and hubs are of different sizes, motor mounting doesn’t quite match the platform, and it’s all a bit like fitting a square peg into a round hole. But with access to the right tools, it’s nothing a little metalwork and welding can’t solve.

For the control system, the ESP32 (with a beautiful CNC-routed custom PCB) sets itself up as a wireless access point that serves a web-based control panel for piloting, and controls two H-bridges to drive the motors. What’s more, it also provides a sound board from which a second operator can trigger appropriate phrases and sounds from the Dalek.

Some folks prefer their remote-controlled Daleks plush and cute instead of large and looming, but we like the smooth movement and imposing stature of this one. Watch it all in action in the video, embedded below.

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Simulating Driven-Dissipative Quantum Spin Dynamics On Consumer Hardware

December 26, 2025 by 4 Comments

Physics simulations using classical mechanics is something that’s fairly easily done on regular consumer hardware, with real-time approximations a common feature in video games. Moving things to the quantum realm gets more complex, though with equilibrium many-body systems still quite solvable. Where things get interesting is with nonequilibrium quantum systems.

These open systems are subject to energy gains and losses that disrupt its equilibrium. The truncated Wigner approximation (TWA) is used as a semi-classical method to solve these, but dissipative spin systems proved tricky. Now however [Hosseinabadi] et al. have put forward a TWA framework (PR article) for driven-dissipative many-body dynamics that works on consumer hardware.

Naturally, even with such optimizations there is still the issue that the TWA is only an approximation. This raises questions such as about how many interactions are required to get a sufficient level of accuracy.

Using classical computers to do these kind of quantum physics simulations has often been claimed to the ideal use of qubit-based quantum computers, but as has been proven repeatedly, you can get by with a regular tensor network or even a Commodore 64 if you’re in a pinch.