Arduino Hacks

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A small, colorful synth built for a 3-year-old. It has five pots, four sliders, and a tiny screen.

Baby’s First Synth Was Daddy’s First Project

November 22, 2025 by 7 Comments

We absolutely adore inspired labor-of-love tales such as this one. [Alastair] wanted to build a synth for his daughter’s third birthday in spite of having no prior hardware knowledge. It became the perfect excuse to learn about CAD, microcontrollers, PCB design, and of course, 3D printing.

So, why a synth for a toddler? Aside from plain old ‘why not?’, the story goes that she received a Montessori busy-type board which she seemed to enjoy, and it reminded [Alastair] of the control surface of a synth. He wondered how hard it could be to build something similar that made sound and didn’t require constant button presses.

[Alastair] began his journey by dusting off a 15-year-old Arduino Inventors Kit. The initial goal was to get potentiometer readings and map them to 12 discrete values, and then emit MIDI messages. This was easy enough, and it was time to move to a synth module and an Elegoo Nano.

The full adventure is definitely worth the read. Be sure to check out the pink version in action after the break. You really don’t wanna miss the lil’ panda bear. Trust us.

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Dark lab setup with scientific looking drink dispenser

Scared For A Drink?

October 31, 2025 by 1 Comment

Halloween is about tricks and treats, but who wouldn’t fancy a bit to drink with that? [John Sutley] decided to complete his Halloween party with a drink dispenser looking as though it was dumped by a backstreet laboratory. It’s not only an impressive looking separating funnel, it even runs on an Arduino. The setup combines lab glassware, servo motors, and an industrial control panel straight from a process plant.

The power management appeared the most challenging part. The three servos drew more current than one Arduino could handle. [John] overcame voltage sag, brownouts, and ghostly resets. A healthy 1000 µF capacitor across the 5-volt rail fixed it. With a bit of PWM control and some C++, [John] managed to finish up his interactive bar system where guests could seal their own doom by pressing simple buttons.

This combines the thrill of Halloween with ‘the ghost in the machine’. Going past the question whether you should ever drink from a test tube – what color would you pick? Lingonberry juice or aqua regia, who could tell? From this video, we wouldn’t trust the bartender on it – but build it yourself and see what it brings you!

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Qualcomm Introduces The Arduino Uno Q Linux-Capable SBC

October 7, 2025 by 89 Comments

Generally people equate the Arduino hardware platforms with MCU-centric options that are great for things like low-powered embedded computing, but less for running desktop operating systems. This looks about to change with the Arduino Uno Q, which keeps the familiar Uno formfactor, but features both a single-core Cortex-M33 STM32U575 MCU and a quad-core Cortex-A53 Qualcomm Dragonwing QRB2210 SoC.

According to the store page the board will ship starting October 24, with the price being $44 USD. This gets you a board with the aforementioned SoC and MCU, as well as 2 GB of LPDDR4 and 16 GB of eMMC. There’s also a WiFi and Bluetooth module present, which can be used with whatever OS you decide to install on the Qualcomm SoC.

This new product comes right on the heels of Arduino being acquired by Qualcomm. Whether the Uno Q is a worthy purchase mostly depends on what you intend to use the board for, with the SoC’s I/O going via a single USB-C connector which is also used for its power supply. This means that a USB-C expansion hub is basically required if you want to have video output, additional USB connectors, etc. If you wish to run a headless OS install this would of course be much less of a concern.

WALL-E’s Forgotten Sibling Rebuilt

September 28, 2025 by 5 Comments

Do you remember the movie WALL-E? Apparently, [Leviathan engineering] did, and he wasn’t as struck by the title character, or Eva, or even the Captain. He was captivated by BURN-E. His working model shows up in the video below.

We’ll be honest. BURN-E didn’t ring a bell for us, though we remember the movie. He grabbed a 3D design for the robot on the Internet and planned out holes for some servos and other hardware.

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Worst Clock Ever Teaches You QR Codes

September 18, 2025 by 9 Comments

[WhiskeyTangoHotel] wrote in with his newest clock build — and he did warn us that it was minimalist and maybe less than useful. Indeed, it is nothing more than a super-cheap ESP32-C3 breakout board with an OLED screen and some code. Worse, you can’t even tell the time on it without pointing your cell phone at the QR code it generates. Plot twist: you skip the QR code and check the time on your phone.

But then we got to thinking, and there is actually a lot to learn from here on the software side. This thing pulls the time down from an NTP server, formats it into a nice human-readable string using strftime, throws that string into a QR code that’s generated on the fly, and then pushes the bits out to the screen. All in a handful of lines of code.

As always, the secret is in the libraries and how you use them, and we wanted to check out the QR code generator, but we couldn’t find an exact match for QRCodeGenerator.h. Probably the most popular library is the Arduino QRCode library by [ricmoo]. It’s bundled with Arduino, but labelled version 0.0.1, which we find a little bit modest given how widely it’s used. It also hasn’t been updated in eight years: proof that it just works?

That library drew from [nayuki]’s fantastically documented multi-language QR-Code-generator library, which should have you covered on any platform you can imagine, with additional third-party ports to languages you haven’t even heard of. That’s where we’d go for a non-Arduino project.

What library did [WTH] use? We hope to find out soon, but at least we found a couple good candidates, and it appears to be a version of one or the other.

We’ve seen a lot of projects where the hacker generates a QR code using some online tool, packs the bits into a C header array, and displays that. That’s fine when you only need a single static QR code, but absolutely limiting when you want to make something dynamic. You know, like an unreadable clock.

You will not be surprised to know that this isn’t the first unreadable QR-code clock we’ve featured here. But it’s definitely the smallest and most instructive.

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PCBs The Prehistoric Way

September 18, 2025 by 46 Comments

When we see an extremely DIY project, you always get someone who jokes “well, you didn’t collect sand and grow your own silicon”. [Patrícia J. Reis] and [Stefanie Wuschitz] did the next best thing: they collected local soil, sieved it down, and fired their own clay PCB substrates over a campfire. They even built up a portable lab-in-a-backpack so they could go from dirt to blinky in the woods with just what they carried on their back.

This project is half art, half extreme DIY practice, and half environmental consciousness.  (There’s overlap.)  And the clay PCB is just part of the equation. In an effort to approach zero-impact electronics, they pulled ATmega328s out of broken Arduino boards, and otherwise “urban mined” everything else they could: desoldering components from the junk bin along the way.

The traces themselves turned out to be the tricky bit. They are embossed with a 3D print into the clay and then filled with silver before firing. The pair experimented with a variety of the obvious metals, and silver was the only candidate that was both conductive and could be soldered to after firing. Where did they get the silver dust? They bought silver paint from a local supplier who makes it out of waste dust from a jewelry factory. We suppose they could have sat around the campfire with some old silver spoons and a file, but you have to draw the line somewhere. These are clay PCBs, people!

Is this practical? Nope! It’s an experiment to see how far they can take the idea of the pre-industrial, or maybe post-apocalyptic, Arduino. [Patrícia] mentions that the firing is particularly unreliable, and variations in thickness and firing temperature lead to many cracks. It’s an art that takes experience to master.

We actually got to see the working demos in the flesh, and can confirm that they did indeed blink! Plus, they look super cool. The video from their talk is heavy on theory, but we love the practice.

DIY clay PCBs make our own toner transfer techniques look like something out of the Jetsons.

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Theremin-Style MIDI Controller Does It With Lasers

September 7, 2025 by 7 Comments

Strictly speaking, a Theremin uses a pair of antennae that act as capacitors in a specific R/C circuit. Looking at [aritrakdebnath2003]’s MIDI THEREMIN, we see it works differently, but it does play in the manner of the exotic radio instrument, so we suppose it can use the name.

The MIDI THEREMIN is purely a MIDI controller. It sends note data to a computer or synthesizer, and from there, you can get whatever sound at whatever volume you desire. The device’s brain is an Arduino Uno, and MIDI-out for the Arduino has been a solved problem for a long while now.

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