Piano Doorbell Adds Music To Your Home

June 8, 2025 by Lewin Day 16 Comments

Regular ding-dong doorbells are fun and all, but it can be nice to put something a little more special by your front door. To that end, [Arpan Mondal] built this neat little piano doorbell to make visiting his home just a touch more fun.

The heart of the build is an ESP32 microcontroller. It’s responsible for reading the state of five 3D printed piano keys: three white, two black. It’s nowhere near a full octave, but for a doorbell, it’s enough. When a key is pressed, the ESP32 plays a short audio sample embedded within the program code itself. This is done with the help of a PAM8403 audio amplifier module, which jacks up the output to drive the doorbell speaker loud enough to be heard throughout the home. It’s not exactly studio quality audio, but for a doorbell, it sounds pretty solid.

If you’re looking for a fun and easy build to make your home just a little bit more whimsical, it’s hard to beat something like this. Your musical friends will love it—they might even develop an intro riff of their very own. We’ve featured some other fun doorbell builds before, too—the best of which are the Halloween projects.
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When Wireless MIDI Has Latency, A Hardwired Solution Saves The Day

June 7, 2025 by Lewin Day 14 Comments

[Moby Pixel] wanted to build a fun MIDI controller. In the end, he didn’t build it just once, but twice—with the aim of finding out which microcontroller was most fit for this musical purpose. Pitted against each other? The ESP32 and Raspberry Pi Pico.

The MIDI controller itself is quite fetching. It’s built with a 4 x 4 array of arcade buttons to act as triggers for MIDI notes or events. They’re assembled in a nice wooden case with a lovely graphic wrap on it. The buttons themselves are wired to a microcontroller, which is then responsible for sending MIDI data to other devices.

At this point, the project diverges. Originally, [Moby Pixel] set the device up to work with an ESP32 using wireless MIDI over Bluetooth. However, he soon found a problem. Musical performance is all about timing, and the ESP32 setup was struggling with intermittent latency spikes that would ruin the performance. Enter the Raspberry Pi Pico using MIDI over USB. The hardwired solution eliminated the latency problems and made the controller far more satisfying to use.

There may be solutions to the latency issue with the wireless ESP32 setup, be they in code, hardware configuration, or otherwise. But if you want to play with the most accuracy and the minimum fuss, you’ll probably prefer the hardwired setup.

Latency is a vibe killer in music as we’ve explored previously.

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The bill of materials and the assembled smartwatch.

Piko, Your ESP32 Powered Fitness Buddy

June 5, 2025 by John Elliot V 3 Comments

Over on Hackaday.io there’s a fun and playful write-up for a fun and playful project — the Piko, an ESP32 powered smartwatch.

Our hackers [Iloke Alusala], [Lulama Lingela], and [Rafael Cardoso] teamed up to design and manufacture this wrist-worn fitness wearable. Made from an ESP32 Beetle C6 and using an attached accelerometer with simple thresholds the Piko can detect if you’re idle, walking, jogging, or sprinting; and at the same time count your steps.

The team 3D printed the requisite parts in PLA using the printer in their university makerspace. In addition to the ESP32 and printed parts, the bill of materials includes a 240×240 IPS TFT LCD display, a LIS331HH triple-axis accelerometer, a 200 mAh battery, and of course, a watch strap.

Demonstrating splendid attention to detail, and inspired by the aesthetic of the Tamagotchi and pixel art, the Piko mimics your current activity with a delightful array of hand-drawn animations on its display. Should you want to bring a similar charm to your own projects, all the source is available under the MIT license.

If you’re interested in smartwatch technology be sure to check out our recent articles: Smartwatches Could Flatten The Curve Of The Next Pandemic and Custom Smartwatch Makes Diabetes Monitoring Easier For Kids.

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3D Printed Tank Has A Cannon To Boot

June 3, 2025 by Lewin Day 7 Comments

Few of us will ever find ourselves piloting a full-sized military tank. Instead, you might like to make do with the RC variety. [TRDB] has whipped up one of their own design which features a small little pellet cannon to boot.

The tank is assembled from 3D printed components — with PETG filament being used for most of the body and moving parts, while the grippy parts of the treads are printed in TPU. The tank’s gearboxes consist of printed herringbone gears, and are driven by a pair of powerful 775 brushed DC motors, which are cooled by small 40 mm PC case fans. A rather unique touch are the custom linear actuators, used to adjust the tank’s ride height and angle relative to the ground. The small cannon on top is a flywheel blaster that fires small plastic pellets loaded from a simple drum magazine. Running the show is an ESP32, which responds to commands from [TRDB]’s own custom RC controller built using the same microcontroller.

As far as DIY RC tanks go, this is a very complete build. We’ve seen some other great work in this space, like this giant human-sized version that’s big enough to ride in.

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Planetary Poetry With A Tiny Digital Core

June 2, 2025 by Heidi Ulrich 7 Comments

Some hacks just tickle the brain in a very particular way. They’re, for a change, not overly engineered; they’re just elegant, anachronistic, and full of mischief. That’s exactly what [Frans] pulls off with A Gentleman’s Orrery, a tiny, simple clockwork solar system. Composed of shiny brass and the poise of 18th-century craftsmanship, it hides a modern secret: there’s barely any clockwork inside. You can build it yourself.

Peek behind the polished face and you’ll find a mechanical sleight of hand. This isn’t your grandfather’s gear-laden planetarium. Instead of that, it operates on a pared-down system that relies on a stepper motor, driving planetary movement through a 0.8 mm axle nested inside a 1 mm brass tube. That micro-mechanical coupling, aided by a couple of bevel gears, manages to rotate the Moon just right, including its orientation. Most of the movement relies on clever design, not gear cascades. The real wizardry happens under the hood: a 3D-printed chassis cradles an ESP32-C6, a TTP223 capacitive touch module, STSPIN220 driver, and even a reed switch with magnetic charging.

You can even swap out the brass for a stone shell where the full moon acts as the touch control. It’s tactile, it’s poetic, and therefore, a nice hack for a weekend project. To build it yourself, read [Frans]’ Instructable.

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3D Printing A Capable RC Car

June 2, 2025 by Lewin Day 6 Comments

You can buy all sorts of RC cars off the shelf, but doing so won’t teach you a whole lot. Alternatively, you could follow [TRDB]’s example, and design your own from scratch.

The Lizard, as it is known, is a fun little RC car. It’s got a vaguely Formula 1-inspired aesthetic, and looks fetching with the aid of two-tone 3D printed parts. It’s designed for speed and handling, with a rear-wheel-drive layout and sprung suspension at all four corners to soak up the bumps. The majority of the vehicle is 3D printed in PETG, including the body and the gearbox and differential. However, some suspension components are made in TPU for greater flexibility and resistance to impact. [TRDB] specified commercial off-the-shelf wheels to provide good grip that couldn’t easily be achieved with 3D-printed tires. An ESP32 is responsible for receiving commands from [TRDB’s] custom RC controller running the same microcontroller. It sends commands to the speed controller that runs the Lizard’s brushed DC motor from a 3S lithium-polymer battery.

The final product looks sleek and handles well. It also achieved a GPS-verified top speed of 48 km/h as per [TRDB’s] testing. We’ve seen some other great DIY RC cars over the years, too, like this example that focuses on performance fundamentals. Video after the break.

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2025 Pet Hacks Challenge : Poopopticon Is All Up In Kitty’s Business

May 29, 2025 by Tyler August 6 Comments

After seeing this project, we can say that [James] must be a top-tier roommate. He has two flatmates– one human, one feline, and the feline flatmate’s litterbox was located in a bathroom close to the other human’s room. The odors were bothersome. A bad roommate might simply say that wasn’t their problem, but not [James].

Instead, he proclaimed “I shall build a poopopticon to alert me so I may clean the litterbox immediately, before smells can even begin to occur, thus preserving domestic harmony!”* We should all aspire to be more like [James].

It was, admittedly, a fairly simple project. Rather than dive into feline facial recognition, since it only has to detect a single cat, [James] used a simple IR sensor out of his parts bin, the sort you see on line-following robots. The microcontroller, an ESP8266, also came from his parts bin, making this project eligible for the ‘lowest budget’ award, if the contest had one.

The ESP8266 is set to send a message to a waiting webhook. In this case it is linked to a previous project, a smart ‘ring light’ [James] uses to monitor his Twitch chats. He’s also considered hooking it up to his lazy-esp32-banner for a big scrolling ‘change the litterbox!’ message. Since it’s just a webhook, the sky is the limit. Either way, the signal gets to its recipient and the litter gets changed before it smells, ensuring domestic bliss at [James]’ flat. If only all our roommates had been more like [James], we’d be much less misanthropic today.