EclairM0, The Pocket Notepad

April 28, 2025 by Matt Varian 6 Comments

Roughly the size of a Tic Tac container, this project packs a punch in a compact package. [Matt] sent in this beautifully documented pocket device that brings back great memories of texting on early cellphones.

The EclairM0’s firmware is written in TinyGo, a language he hadn’t used before but found perfect for a microcontroller project where storage space is tight. The 14-button input mimics early phone keypads, using multi-tapping and combo key presses to offer various functions. The small SSD1306 OLED display is another highlight. Building on an earlier CircuitPython project, [Matt] optimized the screen’s performance, speeding up its response time for a snappy user experience. The battery picked was only 3 mm thick, however the protection circuity on the battery added another 2 mm so he moved that protection circuity to the main PCB itself to keep it as thin as initially planned.

Weighing just 15 grams, this lightweight device runs on a SAMD21 microcontroller, which supports USB host functionality. This allows the EclairM0 to act as a keyboard, mouse, or even USB peripherals. Housed in a 3D-printed case, the entire project is open-source, with design and firmware files available on GitHub.

We love small handheld projects around here and this well-documented, fun pocket device is no exception, if you want your own he has a page dedicated to helping you build a EclairM0.

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EInk PDA Revisited

April 22, 2025 by Fenix Guthrie 23 Comments

In the dark ages, before iOS and Android phones became ubiquitous, there was the PDA. These handheld computers acted as simple companions to a computer and could often handle calendars, email, notes and more. Their demise was spelled by the smartphone, but the nostalgia of having a simple handheld and romanticizing about the 90’s and 2000’s is still there. Fortunately for the nostalgic among our readers, [Ashtf] decided to give us a modern take on the classic PDAs.

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Self-Hosting A Cluster On Old Phones

April 9, 2025 by Bryan Cockfield 34 Comments

The phones most of us carry around in our pockets every day hold a surprising amount of computing power. It’s somewhat taken for granted now that we can get broadband in our hands in most places; so much so that when one of these devices has reached the end of its life it’s often just tossed in a junk drawer even though its capabilities would have been miraculous only 20 years ago. But those old phones can still be put to good use though, and [Denys] puts a few of them back to work running a computing cluster.

Perhaps the most significant flaw of smartphones, though, is that most of them are locked down so much by their manufacturers that it’s impossible to load new operating systems on them. For this project you’ll need to be lucky enough (or informed enough) to have a phone with an unlockable bootloader so that a smartphone-oriented Linux distribution called postmarketOS can be installed. With this nearly full-fledged Linux distribution to work from, the phones can be accessed by ssh and then used to run Kubernetes for the computing cluster. [Denys] has three phones in his cluster that run a few self-hosted services for him.

[Denys] also points out in his guide that having a phone that can run postmarketOS might save some money when compared to buying a Raspberry Pi to run the same service, and the phones themselves can often be more powerful as well. This is actually something that a few others have noted in the past as well. He’s gone into a considerable amount of detail on how to set this up, so if you have a few old smartphones gathering dust, or even those with broken screens or other physical problems where the underlying computing resources are still usable, it’s a great way to put these machines back to work.

Thanks to [mastro Gippo] for the tip!

Handheld Console Plays Original Pong With Modern E-Waste

March 24, 2025 by Donald Papp 8 Comments

[Simon] wrote in to let us know about DingPong, his handheld portable Pong console. There’s a bit more to it than meets the eye, however. Consider for a moment that back in the 1970s playing Pong required a considerable amount of equipment, not least of which was dedicated electronics and a CRT monitor. What was huge (in more than one way) in the 70s has been shrunk down to handheld, and implemented almost entirely on modern e-waste in the process.

The 1970s would be blown away by a handheld version of Pong, made almost entirely from salvaged components.

DingPong is housed in an old video doorbell unit (hence the name) and the screen is a Sony Video Watchman, a portable TV from 1982 with an amazing 4-inch CRT whose guts [Simon] embeds into the enclosure. Nearly everything in the build is either salvaged, or scrounged from the junk bin. Components are in close-enough values, and power comes from nameless lithium-ion batteries that are past their prime but still good enough to provide about an hour of runtime. The paddle controllers? Two pots (again, of not-quite-the-right values) sticking out the sides of the unit, one for each player.

At the heart of DingPong one will not find any flavor of Arduino, Raspberry Pi, or ESP32. Rather, it’s built around an AY-3-8500 “Ball & paddle” (aka ‘Pong’) integrated circuit from 1977, which means DingPong plays the real thing!

We have seen Pong played on a Sony Watchman before, and we’ve also seen a vintage Pong console brought back to life, but we’re pretty sure this is the first time we’ve seen a Sony Watchman running Pong off a chip straight from the 70s. Watch it in action in the video (in German), embedded below.

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

March 21, 2025 by Lewin Day 10 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!

ClockworkPi Unveils New PicoCalc Handheld

March 14, 2025 by Tom Nardi 34 Comments

Do you like scientific calculators? Don’t bother answering that question, you’re reading Hackaday so we already know the answer. We also know you’re a fan of building things yourself and open source, which makes us fairly sure you’ll be just as interested in the recently announced ClockworkPi PicoCalc as we are.

On the surface, it looks like a chunky scientific calculator, though on further inspection you’ll note it comes equipped with a QWERTY keyboard. But open up the case and what you’ve really got is an elaborate carrier board for the Raspberry Pi Pico. The PicoCalc supports all variants of the microcontroller, but realistically we can’t think of any reason that you wouldn’t just use the latest version.

With the MCU connected, you’ll have access to the PicoCalc’s 320×320 4-inch IPS screen, backlit I2C-connected keyboard, SD card slot, 8 MB PSRAM, and dual PWM speakers. Power is provided by a pair of 18650 cells (which you’ll need to supply on your own), and the board has the necessary circuitry to charge them up over USB-C.

Everything is housed in an injection molded case, but the project page says all the necessary CAD files will be eventually be released under the GPL v3 so you can 3D print or CNC your own enclosure. For now though, the only thing of note that seems to be in the PicoCalc GitHub repository is a PCB schematic.

The software side of things is a little less clear. The page mentions a BASIC interpreter, MP3 playback, and support for various programming languages, but we get the impression that’s just a list of stuff you can run on the Pi Pico. There are a few images that clearly show the PicoCalc actually being used as a calculator however, so there may be an official firmware yet to be revealed.

The PicoCalc kit is on sale now, and will set you back $75 USD — which actually includes a first-generation Pi Pico, on the off chance that you don’t already have a few laying around. We’ve been impressed with the previous offerings from ClockworkPi, so assuming this new kit maintains that same build quality, it seems like a fair enough price.

Solar-Powered E-Reader With No Buttons

March 10, 2025 by Bryan Cockfield 19 Comments

Modern e-readers such as the Amazon Kindle are incredible pieces of engineering, but that doesn’t mean there’s no room for improvement. A device custom-built to your own specifications is always going to provide a more satisfying experience than something purchased off the shelf. That’s why [fel88] put together this custom e-reader which offers a number of unique features, such as a solar panel on the back and button-free operation.

One issue with modern e-readers, at least as [fel88] sees it, is that they have a lot of unnecessary features. This project removes most of them, stripping down the device to its core functionality: a straightforward menu for selecting books and gesture-sensing for navigating the menu as well as changing the pages. The only physical input on the device is a small reed switch to turn the device on. A 3D printed case holds the e-ink display and encloses the inner workings, driven by an Arduino Mega 2560 and powered by three lithium-ion capacitors (LICs) and a small solar panel.

By dropping all of the unnecessary features, the device doesn’t need to waste energy with things like WiFi or Bluetooth and can get around 880 pages on a single charge, not counting any extra energy coming in through the solar panel while it’s operating. The LICs will also theoretically improve its life cycle as well. If you’re still stuck with a paperweight when you formerly had a working e-reader, though, there are plenty of ways to bring old devices back to life as well.