Mural: The Plotter That Draws On Walls

March 24, 2025 by Lewin Day 16 Comments

Let’s say you’ve got a big bare wall in your home, and you want some art on it. You could hang a poster or a framed artwork, or you could learn to paint a mural yourself. Or, like [Nik Ivanov], you could build a plotter called Mural, and get it to draw something on the wall for you.

The build is straightforward enough. It uses a moving carriage suspended from toothed belts attached to two points up high on the wall. Stepper motors built into the carriage reel the belts in and out to move it up and down the wall, and from side to side. In this case, [Nik] selected a pair of NEMA 17 steppers to do the job. They’re commanded by a NodeMCU ESP32, paired with TMC2209 stepper motor drivers. The carriage also includes a pen lifter, which relies on a MG90s servo to lift the drawing implement away from the wall.

The build is quite capable, able to recreate SVG vector graphics quite accurately, without obvious skew or distortion. [Nik] has been using the plotter with washable Crayola markers, so he can print on the wall time and again without leaving permanent marks. It’s a great way to decorate—over and over again—on a budget. Total estimated cost is under $100, according to [Nik].

We’ve featured some neat projects along these lines before, too. Video after the break.

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The SNES Seems To Be Getting Faster Over Time

March 24, 2025 by Lewin Day 24 Comments

Every Super Nintendo console should run at the same speed. They were all built in factories with the same components so they should all operate at the steady clip mandated by Nintendo all those years ago. Except, apparently, the SNES is speeding up as it gets older.

The matter was brought to the public’s attention by the [TASBot] team, a group within the speedrunning community. If anyone was going to notice vintage consoles suddenly running a hair faster, you could bet it would be the speedrunners. Soon enough, a call was put out to crowdsource some data. Submitters were asked to run a set piece of code to test the DSP sample rate on consoles when cold and warm, to get the best idea of what was going on.

As reported by Ars Technica, the group seems to have pinned down the problem to the SNES’s Audio Processing Unit. It’s supposed to run at 24.576 MHz, with a sample rate of 32,000 Hz. However, over the years, emulator developers and speedrunners had noticed that 32,040 Hz seemed to be a more realistic figure for what real consoles were actually running the DSP sample rate at. Developers found that building emulators to run the DSP at this rate was important to run commercial games as expected, suggesting the hardware might have always been a little faster than expected.

However, more recently, it seems that the average speed of the DSP sample rate has increased further. The average result collected by [TASBot] from modern consoles is 32,076 Hz. What’s more interesting is the range of submitted figures—from 31,976 Hz to 32,349 Hz. It seems that the DSP’s ceramic resonator—used instead of a quartz crystal—might degrade over time, causing the speedup. [TASBot] team members also tested temperature changes, but only found a 32 Hz variation from a frozen SNES to one at room temperature.

The fact that console components degrade over time isn’t exactly news; we’ve featured plenty of articles on leaky batteries and corroded traces. Still, for speedrunners, the idea that the hardware standard itself can shift over time? It’s like feeling quicksand under your feet. What even is reality anymore?

[Thanks to s7726 for the tip!]

A Cute Handheld Gaming Device That You Can Build In An Altoids Tin

March 21, 2025 by Lewin Day 9 Comments

The MintyPi was a popular project that put a Raspberry Pi inside an Altoids tin to make a pocketable gaming handheld. Unfortunately, it’s not the easiest build to replicate anymore, but [jackw01] was still a fan of the format. Thus was born the Pi Tin—a clamshell handheld for portable fun!

Neat, huh? More pocket-sized than the Game Boy Pocket.

The build is based around the Raspberry Pi Zero 2W, which packs more power than the original Pi Zero into the same compact form factor. It’s combined with a 320 x 240 TFT LCD screen and a 2000 mAh lithium-polymer battery which provides power on the go.

There are also a pair of custom PCBs used to lace everything together, including the action buttons, D-pad, and power management hardware. Depending on your tastes, you have two main enclosure options. You can use the neat 3D printed clamshell seen here in beautiful teal, or you can go with the classic Altoids tin build—just be careful when you’re cutting it to suit! Files can be found on GitHub for the curious.

We love a good handheld project around these parts; it’s particularly awesome how much gaming you can fit in your pocket given the magic of the Raspberry Pi and modern emulation. If you’re cooking up your own little retro rig, don’t hesitate to let us know!

Turning A Kombucha Bottle Into A Plasma Tube

March 21, 2025 by Lewin Day 9 Comments

Kombucha! It’s a delicious fermented beverage that is kind to your digestive system and often sold in glass bottles. You don’t just have to use those bottles for healthy drinks, though. As [Simranjit Singh] demonstrates, you can also use them to create your very own plasma tube.

[Simranjit’s] build begins with a nice large 1.4-liter kombucha bottle from the Synergy brand. To make the plasma tube nicely symmetrical, the bottle had its original spout cut off cleanly with a hot wire, with the end then sealed with a glass cap. Electrodes were installed in each end of the tube by carefully drilling out the glass and installing small bolts. They were sealed in place with epoxy laced with aluminium oxide in order to improve the dielectric strength and aid the performance of the chamber. A vacuum chamber was then used to evacuate air from inside the chamber. Once built, [Simranjit] tested the bottle with high voltage supplied from a flyback transformer, with long purple arcs flowing freely through the chamber.

A plasma tube may not be particularly useful beyond educational purposes, but it does look very cool. We do enjoy a nice high-voltage project around these parts, after all.

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Building A Handheld Pong Game

March 21, 2025 by Lewin Day 2 Comments

Pong was one of the first video games to really enter the public consciousness. While it hasn’t had the staying power of franchises like Zelda or Call of Duty, it nonetheless still resonates with gamers today. That includes [Arnov Sharma], who put together this neat handheld version using modern components.

An ESP32 development board serves as the brains of the operation. Capable of operating at many hundreds of megahertz, it has an excessive amount of power for an application as simple as this. Nonetheless, it’s cheap, and it gets the job done. It’s paired with an SSD1306 OLED screen of 124 x 32 resolution. That might not sound like much, but it’s plenty when you’re just drawing two paddles and a ball bouncing between them. Control is via a pair of SMD push buttons for a nice responsive feel.

What’s really neat, though, is the presentation. [Arnov] wrapped the electronics in a neat bean-shaped housing that vaguely apes game controllers of the 16-bit era. Indeed, [Arnov] explains that it was inspired by the Sega Genesis specifically. It looks great with the black PCBs integrated so nicely with the bright orange 3D printed components, and looks quite comfortable to use, too.

It might be a simple project, but it’s done rather well. Just by thinking about color choices and how to assemble the base components, [Arnov] was able to create an attractive and functional game that’s a lot more eye catching than some random boards thrown in an old project box. Indeed, we’ve featured stories on advanced FR4/PCB construction techniques before, too. Meanwhile, if you’re creating your own projects with similar techniques, don’t hesitate to let us know!

High Frequency Food: Better Cutting With Ultrasonics

March 21, 2025 by Lewin Day 36 Comments

You’re cutting yourself a single slice of cake. You grab a butter knife out of the drawer, hack off a moist wedge, and munch away to your mouth’s delight. The next day, you’re cutting forty slices of cake for the whole office. You grab a large chef’s knife, warm it with hot water, and cube out the sheet cake without causing too much trauma to the icing. Next week, you’re starting at your cousin’s bakery. You’re supposed to cut a few thousand slices of cake, week in, week out. You suspect your haggardly knifework won’t do.

In the home kitchen, any old knife will do the job when it comes to slicing cakes, pies, and pastries. When it comes to commercial kitchens, though, presentation is everything and perfection is the bare minimum. Thankfully, there’s a better grade of cutting tool out there—and it’s more high tech than you might think.

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Aluminum Business Cards Make Viable PCB Stencils

March 21, 2025 by Lewin Day 25 Comments

[Mikey Sklar] had a problem—namely, running low on the brass material typically used for making PCB stencils. Thankfully, a replacement material was not hard to find. It turns out you can use aluminum business card blanks to make viable PCB stencils.

Why business card blanks? They’re cheap, for a start—maybe 15 cents each in quantity. They’re also the right thickness, at just ~~0.8 mm~~ 0.18 mm, and they’re flat, unlike rolled materials that can tend to flip up when you’re trying to spread paste. They’re only good for small PCBs, of course, but for many applications, they’ll do just fine.

To cut these, you’ll probably want a laser cutter. [Mikey] was duly equipped in that regard already, which helped. Using a 20 watt fiber laser at a power of 80%, he was able to get nice accurate cuts for the stencils. Thanks to the small size of the PCBs in question, the stencils for three PCBs could be crammed on to a single card.

If you’re not happy with your existing PCB stencil material, you might like to try these aluminium blanks on for size. We’ve covered other stenciling topics before, too.

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