Cardboard is a surprisingly durable material, especially in its corrugated form. It’s extremely lightweight for its strength, is easy to work, can be folded and formed into almost any shape, is incredibly inexpensive, and when it has done its duty it can be recycled back into more paper. For these reasons, it’s often used in packaging material but it can be used to build all kinds of things outside of ensuring that products arrive at their locations safely. This working cardboard record player is one example.

While the turntable doesn’t have working records in the sense that the music is etched into them like vinyl, each has its own RFID chip embedded that allows the ESP32 in the turntable’s body to identify them. Each record corresponds to a song stored on an SD card that instructs the ESP32 to play the appropriate song. It also takes care of spinning the record itself with a small stepper motor. There are a few other details on this build that tie it together too, including a movable needle arm held on with a magnet and a volume slider.

As far as a building material goes, cardboard is fairly underrated in our opinion. Besides small projects like this turntable, we’ve also seen it work as the foundation for a computer, and it even has the strength and durability to be built into a wall or even used as shelving material. And, of course, it’s a great material to use when prototyping new designs.

When choosing a low-level language, it’s hard to beat the efficiency of Forth while also maintaining some amount of readability. There are open source options for the language which makes it accessible, and it maintains its prevalence in astronomical and other embedded systems for its direct hardware control and streamlined use of limited resources even though the language started over 50 years ago. Unlike 50 years ago, though, you can now take your own self-contained Forth programmer on the go with you.

The small computer is built on a design that [Dennis] built a while back called my4TH which has its own dedicated 8-bit CPU and can store data in a 256 kB EEPROM chip. Everything else needed for the computer is built in as well but that original design didn’t include a few features that this one adds, most notably a small 40×4 character LCD and a keyboard. The build also adds a case to tie everything together, with ports on the back for I2C and power plus an RS232 port. An optional battery circuit lets the computer power up without an external power supply as well.

Part of the appeal of Forth for systems like this is that it includes an interpreter and compiler in addition to the programming language itself, meaning that it has everything needed for a usable computer system built right in. For some more details on this unique language, or if you’d like to explore below the world of Python or C, check out [Elliot]’s discussion on the “hacker’s language.”. While Forth can tackle big problems, it can fit on tiny machines, too.

Believe it or not, there was a time when the only way for many of us to play video games was to grab a roll of quarters and head to the mall. Even though there’s a working computer or video game console in essentially every house now doesn’t mean we don’t look back with a certain nostalgia on those times, though. Some have turned to restoring vintage arcade cabinets and others build their own. This hackerspace got a unique request for a full-sized arcade cabinet that was also easily portable as well.

The original request was for a portable arcade cabinet, and the original designs were for a laptop-like tabletop arcade. But further back-and-forth made it clear they wanted full-size cabinets that just happened to also be portable. So with that criteria in mind the group started building the units. The updated design is modular, allowing the controls, monitor, and Raspberry Pi running the machines to be in self-contained units, with the cabinets in two parts that can quickly be assembled on-site. The base is separate and optional, with the top section capable of being assembled on the base or on something like a tabletop or bar, and the electronics section quickly drops in.

While the idea of a Pi-powered arcade cabinet is certainly nothing new, the quick build, prototyping, design, and final product that’s mobile and quickly assembled are all worth checking out. There is even more information on the build at the project’s GitHub page including Fusion 360 models. If you need your cabinets to be even more portable, this tabletop MAME cabinet is a great place to start.

Morse code, often referred to as continuous wave (CW) in radio circles, has been gradually falling out of use for a long time now. At least in the United States, ham radio licensees don’t have to learn it anymore, and the US Coast Guard stopped using it even for emergencies in 1999. It does have few niche use cases, though, as it requires an extremely narrow bandwidth and a low amount of power to get a signal out and a human operator can usually distinguish it even if the signal is very close to the noise floor. So if you want to try and learn it, you might want to try something like this Morse trainer from [mircemk].

While learning CW can be quite tedious, as [mircemk] puts it, it’s actually fairly easy for a computer to understand and translate so not a lot of specialized equipment is needed. This build is based around the Arduino Nano which is more than up for the job. It can accept input from any audio source, allowing it to translate radio transmissions in real time, and can also be connected to a paddle or key to be used as a trainer for learning the code. It’s also able to count the words-per-minute rate of whatever it hears and display it on a small LCD at the front of the unit which also handles displaying the translations of the Morse code.

If you need a trainer that’s more compact for on-the-go CW, though, take a look at this wearable Morse code device based on the M5StickC Plus instead.

Until the early 2000s, the computer processors available on the market were essentially all single-core chips. There were some niche layouts that used multiple processors on the same board for improved parallel operation, and it wasn’t until the POWER4 processor from IBM in 2001 and later things like the AMD Opteron and Intel Pentium D that we got multi-core processors. If things had gone just slightly differently with this experimental platform, though, we might have had multi-processor systems available for general use as early as the 80s instead of two decades later.

The team behind this chip were from the University of Califorina, Berkeley, a place known for such other innovations as RAID, BSD, SPICE, and some of the first RISC processors. This processor architecture would be based on RISC as well, and would be known as Symbolic Processing Using RISC. It was specially designed to integrate with the Lisp programming language but its major feature was a set of parallel processors with a common bus that allowed for parallel operations to be computed at a much greater speed than comparable systems at the time. The use of RISC also allowed a smaller group to develop something like this, and although more instructions need to be executed they can often be done faster than other architectures.

The linked article from [Babbage] goes into much more detail about the architecture of the system as well as some of the things about UC Berkeley that made projects like this possible in the first place. It’s a fantastic deep-dive into a piece of somewhat obscure computing history that, had it been more commercially viable, could have changed the course of computing. Berkeley RISC did go on to have major impacts in other areas of computing and was a significant influence on the SPARC system as well.

If you missed the introduction of the Axis-49 and Axis-64 keyboards by C-Thru Music, you’re definitely not alone. At the time it was a new musical instrument that was based on the harmonic table, but it launched during the Great Recession and due to its nontraditional nature and poor timing, the company went out of business. But the harmonic table layout has a number advantages for musicians over other keyboard layouts, so [Ben] has brought his own version of the unique instrument to life in his latest project.

Called the Midihex, the keyboard has a number of improvements over the version from C-Thru Music, most obviously its much larger 98 playable keys and five function keys. The keys themselves are similar to Cherry MX keys but which use Hall-effect sensors. This style of key allows the device to send continuous key position information to the host computer, and since this is a MIDI instrument, this capability allows it to support a MIDI protocol called MIDI Polyphonic Expression (MPE) which allows each note to be more finely controlled by the musician than a standard MIDI instrument. The PCB is powered by a Teensy 4.1 at the core.

For any musicians that haven’t tried out a harmonic table before, an instrument like this might be worth trying out. The layout provides easier chord and scale patterns, and for beginner musicians it can have a much shallower learning curve than other types of instruments. If you can’t find an original Axis-49 or Axis-64 anywhere to try out, though, we actually posted a teardown of one way back in 2009 when the company was still producing instruments.

Batman is a compelling superhero for enough reasons that he’s been a cultural force for the better part of a century. His story has complex characters, interesting explorations of morality, iconic villains, and of course a human superhero who gets his powers from ingenuity instead of a fantastical magical force. There are a number features of the Batman universe that don’t translate well to the real world, though, such as a costume that would likely be a hindrance in fights, technology that violates the laws of physics, and a billionaire that cares about regular people, but surprisingly enough his legendary Batwing jet airplane actually seems like it might be able to fly.

While this is admittedly a model plane, it flies surprisingly well for its nontraditional shape. [hotlapkyle] crafted it using mostly 3D printed parts, and although it took a few tries to get it working to his standards, now shoots through the air quite well. It uses an internal electric ducted fan (EDF) to get a high amount of thrust, and has elevons for control. There are two small vertical stabilizer fins which not only complete the look, but allow the Batwing to take to the skies without the need for a flight controller.

Not only is the build process documented in the video linked below with some interesting tips about building RC aircraft in general, but the STL files for this specific build are available for anyone wanting to duplicate the build or expand on it. There are plenty of other interesting 3D-printed models on [hotlapkyle]’s page as well that push the envelope of model aircraft. For some other niche RC aircraft designs we’ve seen in the past be sure to check out this F-35 model that can hover or this tilt-rotor Osprey proof-of-concept.

Thanks to [Keith] for the tip!

As far as model construction sets go, LEGO is by far the most popular brand for building not only pre-planned models but whatever the builder can imagine. There are a few others out there though, some with some interesting features. Meccano (or Erector in North America) is a construction set based around parts that are largely metal including its fasteners, which allows for a different approach to building models than other systems including the easy addition of electricity. [Craig], a member of the London Meccano Club, is demonstrating his model Enigma machine using this system for all of its parts and adding some electricity to make the circuitry work as well.

The original Enigma machine was an electronic cypher used by the German military in World War 2 to send coded messages. For the time, its code was extremely hard to break, and led to the British development of the first programmable electronic digital computer to help decipher its coded messages. This model uses Meccano parts instead to recreate the function of the original machine, with a set of keys similar to a typewriter which, when pressed, advance a set of three wheels. The wheels all have wiring in them, and depending on their initial settings will light up a different character on a display.

There are a few modifications made to the design (besides the use of a completely different set of materials) but one of the main ones was eliminating the heavy leaf springs of the original for smaller and easier-to-manage coil springs, which are also part of the electrical system that creates the code. The final product recreates the original exceptionally faithfully, with plans to create a plugboard up next, and you can take a look at the inner workings of a complete original here.

Thanks to [Tim] for the tip!

Although Moore’s Law has slowed at bit as chip makers reach the physical limits of transistor size, researchers are having to look to other things other than cramming more transistors on a chip to increase CPU performance. ARM is having a bit of a moment by improving the performance-per-watt of many computing platforms, but some other ideas need to come to the forefront to make any big pushes in this area. This startup called Flow Computing claims it can improve modern CPUs by a significant amount with a slight change to their standard architecture.

It hopes to make these improvements by adding a parallel processing unit, which they call the “back end” to a more-or-less standard CPU, the “front end”. These two computing units would be on the same chip, with a shared bus allowing them to communicate extremely quickly with the front end able to rapidly offload tasks to the back end that are more inclined for parallel processing. Since the front end maintains essentially the same components as a modern CPU, the startup hopes to maintain backwards compatibility with existing software while allowing developers to optimize for use of the new parallel computing unit when needed.

While we’ll take a step back and refrain from claiming this is the future of computing until we see some results and maybe a prototype or two, the idea does show some promise and is similar to some ARM computers which have multiple cores optimized for different tasks, or other computers which offload non-graphics tasks to a GPU which is more optimized for processing parallel tasks. Even the Raspberry Pi is starting to take advantage of external GPUs for tasks like these.

Unless you’re living in a bicycle paradise like the Netherlands, most people will choose to add some sort of illumination to their bicycle to help drivers take note that there’s something other than a car using the road. Generally, simple flashing LEDs for both the front and the rear is a pretty good start, but it doesn’t hurt to add a few more lights to the bicycle or increase their brightness. On the other hand, if you want to add some style to your bicycle lighting system then this persistence of vision (POV) display called the BikeBeamer from [locxter] might be just the thing.

The display uses four LED strips, each housed in their own 3D printed case which are installed at 90-degree angles from one another in between the spokes of a standard bicycle wheel. An ESP32 sits at the base of one of the strips and is responsible for storing the image and directing the four displays. This is a little more complex than a standard POV display as it’s also capable of keeping up with the changing rotational speeds of the bicycle wheels when in use. The design also incorporates batteries so that no wires need to route from the bike frame to the spinning wheels.

This is an ongoing project for [locxter] as well, meaning that there are some planned upgrades even to this model that should be in the pipe for the future. Improving the efficiency of the code will hopefully allow for more complex images and even animations to be displayed in the future, and there are also some plans to improve the PCB as well with all surface-mount components. There are a few other ways to upgrade your bike’s lighting as well, and we could recommend this heads-up headlight display to get started.

While most of us have likely spun up a virtual machine (VM) for one reason or another, venturing into the world of containerization with software like Docker is a little trickier. While the tools Docker provides are powerful, maintain many of the benefits of virtualization, and don’t use as many system resources as a VM, it can be harder to get the hang of setting up and maintaining containers than it generally is to run a few virtual machines. If you’ve been hesitant to try it out, this guide to getting a Docker container up and running is worth a look.

The guide goes over the basics of how Docker works to share system resources between containers, including some discussion on the difference between images and containers, where containers can store files on the host system, and how they use networking resources. From there the guide touches on installing Docker within a Debian Linux system. But where it really shines is demonstrating how to use Docker Compose to configure a container and get it running. Docker Compose is a file that configures a number of containers and their options, making it easy to deploy those containers to other machines fairly straightforward, and understanding it is key to making your experience learning Docker a smooth one.

While the guide goes through setting up a self-hosted document management program called Paperless, it’s pretty easy to expand this to other services you might want to host on your own as well. For example, the DNS-level ad-blocking software Pi-Hole which is generally run on a Raspberry Pi can be containerized and run on a computer or server you might already have in your home, freeing up your Pi to do other things. And although it’s a little more involved you can always build your own containers too as our own [Ben James] discussed back in 2018.

Intel has had a deathgrip on the PC world since the standardization around the software and hardware available on IBM boxes in the 90s. And if you think you’re free of them because you have an AMD chip, that’s just Intel’s instruction set with a different badge on the silicon. At least AMD licenses it, though — in the 80s there was another game in town that didn’t exactly ask for permission before implementing, and improving upon, the Intel chips available at the time.

The NEC V20 CPU was a chip that was a drop-in replacement for the Intel 8088 and made some performance improvements to it as well. Even though the 186 and 286 were available at the time of its release, this was an era before planned obsolescence as a business model was king so there were plenty of 8088 systems still working and relevant that could take advantage of this upgrade. In fact, the V20 was able to implement some of the improved instructions from these more modern chips. And this wasn’t an expensive upgrade either, with kits starting around $16 at the time which is about $50 today, adjusting for inflation.

This deep dive into the V20 isn’t limited to a history lesson and technological discussion, though. There’s also a project based on Arduino which makes use of the 8088 with some upgrades to support the NEC V20 and a test suite for a V20 emulator as well.

If you had an original IBM with one of these chips, though, things weren’t all smooth sailing for this straightforward upgrade at the time. A years-long legal battle ensued over the contents of the V20 microcode and whether or not it constituted copyright infringement. Intel was able to drag the process out long enough that by the time the lawsuit settled, the chips were relatively obsolete, leaving the NEC V20 to sit firmly in retrocomputing (and legal) history.

While 3D printers have evolved over the past two decades from novelties to powerful prototyping tools, the amount of support systems have advanced tremendously as well. From rudimentary software that required extensive manual input and offered limited design capabilities, there’s now user-friendly interfaces with more features than you could shake a stick at. Hardware support has become refined as well with plenty of options including lighting, ventilation, filament recycling, and tool changers. It’s possible to automate some of these subsystems as well like [Caelestis Workshop] has done with this relay control box.

This build specifically focuses on automating or remotely controlling the power, enclosure lighting, and the ventilation system of [Caelestis Workshop]’s 3D printer but was specifically designed to be scalable and support adding other features quickly. A large power supply is housed inside of a 3D printed enclosure along with a Raspberry Pi. The Pi controls four relays which are used to control these various pieces hardware along with the 3D printer. That’s not the only thing the Pi is responsible for, though. It’s also configured to run Octoprint, a piece of open-source software that adds web interfaces for 3D printers and allows their operation to be monitored and controlled remotely too.

With this setup properly configured, [Caelestis Workshop] can access their printer from essentially any PC, monitor their prints, and ensure that ventilation is running. Streamlining the print process is key to reducing the frustration of any 3D printer setup, and this build will go a long way to achieving a more stress-free environment. In case you missed it, we recently hosed a FLOSS Weekly episode talking about Octoprint itself which is worth a listen especially if you haven’t tried this piece of software out yet.

The progress for electronics over the past seven decades or so has always trended towards smaller or more dense components. Moore’s Law is the famous example of this, but even when we’re not talking about transistors specifically, technology tends to get either more power efficient or smaller. This MIDI keyboard, for example, is small enough that it will fit in the space of a standard business card which would have been an impossibility with the technology available when MIDI first became standardized, and as such is the latest entry in our Business Card Challenge.

[Alana] originally built this tiny musical instrument to always have a keyboard available on the go, and the amount of features packed into this tiny board definitely fits that design goal. It has 18 keys with additional buttons to change the octave and volume, and has additional support for sustain and modulation as well. The buttons and diodes are multiplexed in order to fit the IO for the microcontroller, a Seeed Studio Xiao SAMD21, and it also meets the USB-C standards so it will work with essentially any modern computer available including most smartphones and tablets so [Alana] can easily interface it with Finale, a popular music notation software.

Additionally, the project’s GitHub page has much more detail including all of the Arduino code needed to build a MIDI controller like this one. This particular project has perhaps the best size-to-usefulness ratio we’ve seen for compact MIDI controllers thanks to the USB-C and extremely small components used on the PCB, although the Starshine controller or these high-resolution controllers are also worth investigating if you’re in the market for compact MIDI devices like this one.

If you’ve ever seen artifacts on a digital picture of a computer monitor, or noticed an unsettling shifting pattern on a TV displaying someone’s clothes which have stripes, you’ve seen what’s called a Moiré pattern where slight differences in striping of two layers create an emergent pattern. They’re not always minor annoyances though; in fact they can be put to use in all kinds of areas from art to anti-counterfeiting measures. [Moritz] decided to put a few together to build one of the more unique clock displays we’ve seen.

The clock itself is made of four separate Moiré patterns. The first displays the hours with a stretching pattern, the second and third display the minutes with a circular pattern, and the seconds are displayed with a a spiral type. The “hands” for the clock are 3D printed with being driven by separate stepper motors with hall effect sensors for calibration so that the precise orientation of the patterns can be made. A pair of Arduinos control the clock with the high-accuracy DS3231 module keeping track of time, and [Moritz] built a light box to house the electronics and provide diffuse illumination to the display.

Moiré patterns can be used for a number of other interesting use cases we’ve seen throughout the years as well. A while back we saw one that helps ships navigate without active animations or moving parts and on a much smaller scale they can also be used for extremely precise calipers.

Despite the name, so-called “instant” noodles still need to sit for a few minutes before they’re actually ready to eat. Most people would likely use a simple kitchen timer to let them know when it’s time to chow down, but this unique mechanical timer uses the weight of the noodles themselves to power a timing mechanism.

The timer acts in much the same way that a pendulum clock would, in that a weight provides the energy to drive the clock’s mechanism which releases that energy in discrete steps. Besides a few metal parts and some magnets, the majority of the clock is 3D printed with a small platform on the side where the noodles rest. As the platform falls the weight drives the clock mechanism which will finally alert the user when they finish their descent three minutes later with the help of a small bell. There’s even an analog display which shows the number of minutes remaining before the noodles are ready to eat.

As far as single-purpose kitchen appliances go, this is one that we might find ourselves sacrificing some counter space for not only for the usefulness but also for the aesthetic appeal of the visible clock movements and high-quality design. It could even go beside the automatic ramen cooker for when we’re too busy (or lazy) to even boil the water for instant noodles ourselves.

Thanks to [PietdeVries] for the tip!

Unique clocks are a mainstay around here, and while plenty are “human readable” without any instruction, there are a few that take a bit of practice before someone can glean the current time from them. Word clocks are perhaps on the easier side of non-traditional displays but at the other end are binary clocks or even things like QR code clocks. To get the best of both worlds, though, multiple clock faces can be combined into one large display like this clock build from [imitche3].

The clock is actually three clocks in one. The first was inspired by a binary clock originally found in a kit, which has separate binary “digits” for hour, minute, and second and retains the MAX 7219 LED controller driving the display. A standard analog clock rests at the top, and a third clock called a retrograde clock sits at the bottom with three voltmeters that read out the time in steps. Everything is controlled by an Arduino Nano with the reliable DS3231 keeping track of time. The case can be laser-cut or 3D printed and [imitche3] has provided schematics for both options.

As far as clocks builds go, we always appreciate something which can be used to tell the time without needing any legends, codes, or specialized knowledge. Of course, if you want to take a more complex or difficult clock face some of the ones we’re partial to are this QR code clock which needs a piece of hardware to tell the time that probably already has its own clock on it.

Sometimes it seems like ideas for projects spring out of nothingness from a serendipitous set of circumstances. [Maarten] found himself in just such a situation, with a combination of his existing Tetris novelty lamp and an awkwardly-sized window on a second-floor apartment, he was gifted with the perfect platform for a giant playable Tetris game built into that window.

To make the giant Tetris game easily playable by people walking by on the street, [Maarten] is building as much of this as possible in the browser. Starting with the controller, he designed a NES-inspired controller in JavaScript that can be used on anything with a touch screen. A simulator display was also built in the browser so he could verify that everything worked without needing the giant display at first. From there it was on to building the actual window-sized Tetris display which is constructed from addressable LEDs arranged in an array that matches the size of the original game.

There were some issues to iron out, as would be expected for a project with this much complexity, but the main thorn in [Maarten]’s side was getting his controller to work in Safari on iPhones. That seems to be mostly settled and there were some other gameplay issues to solve, but the unit is now working in his window and ready to be played by any passers-by, accessed by a conveniently-located QR code. Tetris has been around long enough that there are plenty of unique takes on the game, like this project from 2011 that uses Dance Dance Revolution pads for controllers.

For those willing to put some elbow grease into it, there is an almost unlimited supply of 18650 lithium ion batteries around for cheap (or free) just waiting to be put into a battery pack of some sort. Old laptop and power tool batteries are prime sources, as these often fail because of one bad cell while the others are still perfectly usable. [limpkin] built a few of these battery packs and now that he’s built a few, he’s back with a new project that allows him to use four custom packs simultaneously.

The problem with using different battery packs in parallel is that unless the batteries are charged to similar voltages, they could generate a very high and potentially dangerous amount of current when connected in parallel. This circuit board, powered by a small ATtiny microcontroller, has four XT-60 connectors for batteries and a fifth for output. It then watches for current draw from each of the batteries and, using a set of solid-state relays, makes sure that no dangerous overcurrent conditions occur if the batteries are connected with mismatched voltages. The code for the microcontroller is available on this GitHub page as well.

Using an array of batteries with a balancing system like this has a number of uses, from ebikes to off-grid power solutions, and of course if you build your own packs you’ll also want to build a cell balancer of some sort as well. Batteries go outsidelectrical e the realm of theory and into that of chemistry, so we’ll also provide a general warning about working in potentially dangerous situations without specialized knowledge, but you can see how [limpkin] built his original packs here if you want to take a look at one person’s strategy for repurposing old cells.