Author: Lewin Day

3368 Articles

Mechanical 7-Segment Display Combines Servos And Lego

June 25, 2025 by 4 Comments

If you need a seven-segment display for a project, you could just grab some LED units off the shelf. Or you could build something big and electromechanical out of Lego. That’s precisely what [upir] did, with attractive results.

The build relies on Lego Technic parts, with numbers displayed by pushing small black axles through a large yellow faceplate. This creates a clear and easy to read display thanks to the high contrast. Each segment is made up of seven axles that move as a single unit, driven by a gear rack to extend and retract as needed. By extending and retracting the various segments in turn, it’s possible to display all the usual figures you’d expect of a seven-segment design.

It’s worth noting, though, that not everything in this build is Lego. The motors that drive the segments back and forth are third-party components. They’re Geekservo motors, which basically act as Lego-mountable servos you can drive with the electronics of your choice. They’re paired with an eight-channel servo driver board which controls each segment individually. Ideally, though, we’d see this display paired with a microcontroller for more flexibility. [upir] leaves that as an exercise for the viewer for now, with future plans to drive it with an Arduino Uno.

Design files are on Github for the curious. We’ve featured some similar work before, too, because you really can build anything out of Lego. Video after the break.

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The Rise And The Fall Of The Mail Chute

June 25, 2025 by 17 Comments

As the Industrial Age took the world by storm, city centers became burgeoning hubs of commerce and activity. New offices and apartments were built higher and higher as density increased and skylines grew ever upwards. One could live and work at height, but this created a simple inconvenience—if you wanted to send any mail, you had to go all the way down to ground level.

In true American fashion, this minor inconvenience would not be allowed to stand. A simple invention would solve the problem, only to later fall out of vogue as technology and safety standards moved on. Today, we explore the rise and fall of the humble mail chute.

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Digitally-Converted Leica Gets A 64-Megapixel Upgrade

June 24, 2025 by 26 Comments

Leica’s film cameras were hugely popular in the 20th century, and remain so with collectors to this day. [Michael Suguitan] has previously had great success converting his classic Leica into a digital one, and now he’s taken the project even further.

[Michael’s] previous work saw him create a so-called “digital back” for the Leica M2. He fitted the classic camera with a Raspberry Pi Zero and a small imaging sensor to effectively turn it into a digital camera, creating what he called the LeicaMPi. Since then, [Michael] has made a range of upgrades to create what he calls the LeicaM2Pi.

The upgrades start with the image sensor. This time around, instead of using a generic Raspberry Pi camera, he’s gone with the fancier ArduCam OwlSight sensor. Boasting a mighty 64 megapixels, it’s still largely compatible with all the same software tools as the first-party cameras, making it both capable and easy to use. With a  crop factor of 3.7x, the camera’s Voigtlander 12mm lens has a much more useful field of view.

Unlike [Michael’s] previous setup, there was also no need to remove the camera’s IR filter to clear the shutter mechanism. This means the new camera is capable of taking natural color photos during the day.  [Michael] also added a flash this time around, controlled by the GPIOs of the Raspberry Pi Zero. The camera also features a much tidier onboard battery via the PiSugar module, which can be easily recharged with a USB-C cable.

If you’ve ever thought about converting an old-school film camera into a digital shooter, [Michael’s] work might serve as a great jumping off point. We’ve seen it done with DSLRs, before, too! Video after the break.

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Supercon 2024: Repurposing ESP32 Based Commercial Products

June 10, 2025 by 4 Comments

It’s easy to think of commercial products as black boxes, built with proprietary hardware that’s locked down from the factory. However, that’s not always the case. A great many companies are now turning out commercial products that rely on the very same microcontrollers that hackers and makers use on the regular, making them far more accessible for the end user to peek inside and poke around a bit.

Jim Scarletta has been doing just that with a wide variety of off-the-shelf gear. He came down to the 2024 Hackaday Superconference to tell us all about how you can repurpose ESP32-based commercial products.

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Piano Doorbell Adds Music To Your Home

June 8, 2025 by 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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Wave Drive Made With 3D Printed Parts

June 8, 2025 by 10 Comments

You can get just about any gear reduction you want using conventional gears. But when you need to get a certain reduction in a very small space with minimal to no backlash, you might find a wave drive very useful. [Mishin Machine] shows us how to build one with (mostly) 3D printed components.

The video does a great job of explaining the basics of the design. Right off the bat, we’ll say this one isn’t fully printed—it relies on off-the-shelf steel ball bearings. It’s easy to understand why. When you need strong, smooth-rolling parts, it’s hard to print competitive spheres in plastic at home. Plastic BBs will work too, though, as will various off-the-shelf cylindrical rollers. The rest is mostly 3D printed, so with the right design, you can whip up a wave drive to suit whatever packaging requirements you might have.

Combined with a stepper motor and the right off-the-shelf parts, you can build a high-reduction gearbox that can withstand high torque and should have reasonable longevity despite being assembled with many  printed components.

We’ve seen other interesting gear reductions before, too.

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Building A Cyberpunk Modular Keyboard

June 7, 2025 by 9 Comments

Perhaps you have a tilt towards glowing cyberpunk peripherals. Perhaps you’ve been hunting for a keyboard that you can position perfectly to suit both your left and right hands. In that case, you might just like this nifty design from [Modern Hobbyist].

The first thing you’ll note is the split design, which allows each half of the keyboard to be placed optimally for each arm’s comfort. They’re linked with a cable, which allows the STM32 microcontroller to read the keys on both sides and then spit out the right stuff upstream over its USB-C connection. The microcontroller is also in charge of running the per-key LED lighting and the LCD screens on each half.

The board owes its sleek and slim design at least in part to using Kailh Choc low-profile switches. They plug in to hotswap compatible sockets so the switches can easily be changed if desired. Keycaps are blank off-the-shelf parts because this is a keyboard for those who aren’t afraid to spend the time establishing the right muscle memory. It might take some adaptation if you’re not used to the staggered columnar layout. However, the LCD screens can display a keymap if you need a little help now and then.

We’ve seen a lot of great split keyboards over the years, including one amusing design made by hacking an existing keyboard in half with a saw.

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