What Do You Call An Ekranoplan With An Outboard Motor?

If there’s one thing [rctestflight] likes, it’s… probably radio controlled test flights. If there are two things [rctestflights] likes, the second one is probably ground-effect vehicles, AKA Ekranoplans. Tired of having them flip over and crash, he’s trying an an innovative solution: stick a planing hull on it.

Ekranoplans have a stability problem because the center-of-pressure isn’t static: as the wing gets closer to the ground, the high pressure cushion of air that creates the ground effect tends to put more lift rearwards. The net effect of that is to torque the vehicle nose-down, which is kind of a self-limiting problem at a fraction of a wingspan’s altitude. The opposite problem is more concerning: the higher the ekranoplan gets, the more it wants to nose up, and there’s nothing to stop it. That leads to the vehicle flipping over. Continue reading “What Do You Call An Ekranoplan With An Outboard Motor?”

3D Printing A Piano Action

Part of the reason there are always free pianos on your digital classifieds listing of choice is that, at least economically speaking, a piano is less of a musical instrument and more of a complicated machine that can and will wear out (not to mention the physical difficulty of actually moving one). Once a piano reaches that point, whether through age, use, or neglect, at that point it’s to intents and purposes worthless. But still, they’re essentially just machines. [Toast] figured that, since 3D printers not only can print all kinds of other machines and musical instruments alike, he would take a stab at combining these two and made his own 3D printed piano.

A piano’s action is the mechanical linkage between the keys and the strings of the piano themselves. Over many hundreds of years this has developed into a complicated series of levers which not only rapidly strike strings when a key is pressed, but also mute the strings while the key is not being pressed and strike the strings in a way that the hammer won’t be pressed into the strings if the player leaves their finger on a key. Rather than try to recreate all of this in meticulous detail, [Toast] has swapped out the strings for a series of tubes which, unlike strings, do not much change their musical behavior if the hammer remains on the tube after being struck. This greatly simplifies the action (and cost) of his miniature piano.

The piano works by positioning hammers above these tubes, which strike downwards when a musician depresses the keys. Rubber bands return the hammers to their upright positions after the key is lifted. The instrument went through a few stages of design as well where [Toast] refined the size and shape of the tubes as well as improved the way by which the hammers are attached to the keys.

Is it still a piano if it has pipes instead of strings? Perhaps, but at the very least we can all agree that he’s built a working keyboard action capable of producing music, if not an outright definitionally-accurate piano. It’s an interesting build that we hope to see more iterations of in the future, if not to build a more functionally accurate 3D printed piano action then to see what is possible from a 3D printer in the piano space. Despite their complexity and weight, pianos are a fundamental and popular instrument in the Western music tradition and we’ve seen many interesting builds around them like this modern player piano built with a series of solenoids. Continue reading “3D Printing A Piano Action”

2025 Component Abuse Challenge: Relay Used As Guitar Pickup

We’ve all built projects that are a rats’ nest of wiring and feature creep, but the best projects in the end are usually those that use a simple solution to elegantly solve a problem. [Kauz] had been thinking about a unique type of electric guitar pickup for a while and rather than purchase an expensive option or build a complex microcontroller-based system he found his elegant solution in the form of a common electronic component.

The core of this idea is that guitar pickups are essentially coils of wire, and are surprisingly similar to the coils of wire found in electromechanical relays. [Kauz] has used six small relays, left them unmodified, and then built an amplifier circuit for each to allow the vibrations of the guitar strings to resonate in the relay coils, eventually producing a sound. Not only do the relays work perfectly well as pickups, but [Kauz] also created a mixing board that allows the six relays to be combined into two channels, allowing for options like stereo sound for different strings directly out of the guitar or for different effects to be applied to different strings.

The build also allows for some interesting options in future versions as well. [Kauz]’s plans are eventually to build this into an instrument which can output polyphonic MIDI signals, where various strings can behave as different instruments. In theory, with six circuits six different instruments can be produced, and we’re excited to see what the next versions will look and sound like. In the meantime, be sure to check out some other guitar pickups we’ve seen that use even simpler parts found lying around the workbench.

Continue reading “2025 Component Abuse Challenge: Relay Used As Guitar Pickup”

The Pi 500 Turned Overkill Bluetooth Keyboard

Perhaps we’ve all found ourselves at one time or another with more computers in use than keyboards and other peripherals at hand to use them with. With a single user you can make do with remote terminals or by simply plugging and unplugging, but with multiple users it’s not so easy.

CNX Software’s [Jean-Luc Aufranc] had just such a problem involving broken keyboards and a forgotten wireless dongle, but fortunately he had just reviewed the latest version of the Raspberry Pi 500 all-in-one computer with the fancy mechanical switches. His keyboard solution is inspired but completely overkill: to use the full power of the compact Linux machine to emulate a Bluetooth keyboard.

At the heart of this hack is btferret, a Bluetooth library. Run the appropriate software on your Pi, and straight away you’ll have a Bluetooth keyboard. It seems there’s a bit of keymap tomfoolery to be had, and hitting the escape key terminates the program — we would be caught by that SO many times! — but it’s one of those simple hacks it pays to know about in case like him you need to get out of a hole and happen to have one of the range of Pi all-in-one machines to hand.

If IRobot Falls, Hackers Are Ready To Wrangle Roombas

Things are not looking good for iRobot. Although their robotic Roomba vacuums are basically a household name, the company has been faltering financially for some time now. In 2024 there was hope of a buyout by Amazon, who were presumably keen to pull the bots into their Alexa ecosystem, but that has since fallen through. Now, by the company’s own estimates, bankruptcy is a very real possibility by the end of the year.

Hackaday isn’t a financial blog, so we won’t get into how and why iRobot has ended up here,  although we can guess that intense competition in the market probably had something to do with it. We’re far more interested in what happens when those millions of domesticated robots start getting an error message when they try to call home to the mothership.

We’ve seen this scenario play out many times before — a startup goes belly up, and all the sudden you can’t upload new songs to some weirdo kid’s media player, or the gadget in your fridge stops telling you how old your eggs are. (No, seriously.) But the scale here is unprecedented. If iRobot collapses, we may be looking at one of the largest and most impactful smart-gadget screw overs of all time.

Luckily, we aren’t quite there yet. There’s still time to weigh options, and critically, perform the kind of research and reverse engineering necessary to make sure the community can keep the world’s Roombas chugging along even if the worst happens.

Continue reading “If IRobot Falls, Hackers Are Ready To Wrangle Roombas”

Running A Minecraft Server On A WiFi Light Bulb

WiFi-enabled ‘smart’ light bulbs are everywhere these days, and each one of them has a microcontroller inside that’s capable enough to run all sorts of interesting software. For example, [vimpo] decided to get one running a minimal Minecraft server.

The Bl602-equipped board inside the LED lightbulb. (Credit: vimpo, YouTube)
The Bl602-equipped board inside the LED lightbulb. (Credit: vimpo, YouTube)

Inside the target bulb is a BL602 MCU by Bouffalo Lab, that features not only a radio supporting 2.4 GHz WiFi and BLE 5, but also a single-core RISC-V CPU that runs at 192 MHz and is equipped with 276 kB of RAM and 128 kB flash.

This was plenty of space for the minimalist Minecraft server [vimpo] wrote several years ago. The project says it was designed for “machines with limited resources”, but you’ve still got to wonder if they ever thought it would end up running on a literal lightbulb at some point.

It should be noted, of course, that this is not the full Minecraft server, and it should only be used for smaller games like the demonstrated TNT run mini game.

Perhaps the next challenge will be to combine a large set of these light bulbs into a distributed computing cluster and run a full-fat Minecraft server? It seems like a waste to leave the BL602s and Espressif MCUs that are in these IoT devices condemned to a life of merely turning the lights on or off when we could have them do so much more.

Continue reading “Running A Minecraft Server On A WiFi Light Bulb”

PLA mail being tested against a sword

3D Printed Mail Is A Modern Solution To An Ancient Problem

The human body and sharp objects don’t get along very well, especially when they are being wielded with ill-intent. Since antiquity there have been various forms of armor designed to protect the wearer, but thankfully these days random sword fights don’t often break out on the street. Still, [SCREEN TESTED] wanted to test the viability of 3D printed chain mail — if not for actual combat, at least for re-enactment purposes.

He uses tough PLA to crank out a bed worth of what looks like [ZeroAlligator]’s PipeLink Chainmail Fabric, which just so happens to be the trending result on Bambu’s MakerWorld currently. The video shows several types of mail on the printer, but the test dummy only gets the one H-type pattern, which is a pity — there’s a whole realm of tests waiting to be done on different mail patterns and filament types.

In any case, the mail holds up fairly well to puncture from scissors and screwdrivers — with a heavy sweater or proper gambeson (a quilted cloth underlayer commonly worn with armor) on underneath, it looks like it could actually protect you. To slashing blows, PLA holds up astoundingly well, barely marked even by slashes from an actual sword. As for projectiles, well, everyone knows that to an arrow, chain mail is made of holes, and this PLA-based armor is no different (as you can see at 8:30 in the video below).

If you want to be really safe when the world goes Mad Max, you’d probably want actual chain mail, perhaps from stainless steel. On the other hand, if someone tries to mug you on the way home from a con, cosplay armor might actually keep you safer than one might first suspect. It’s not great armor, but it’s a great result for homemade plastic armor.

Of course you’d still be better off with Stepahnie Kwolek’s great invention, Kevlar.

Continue reading “3D Printed Mail Is A Modern Solution To An Ancient Problem”