Author: Tom Nardi

2482 Articles

AqMood Is An Air Quality Monitor With An Attitude

March 27, 2025 by No comments

You take your air quality seriously, so shouldn’t your monitoring hardware? If you’re breathing in nasty VOCs or dust, surely a little blinking LED isn’t enough to express your displeasure with the current situation. Luckily, [Tobias Stanzel] has created the AqMood to provide us with some much-needed anthropomorphic environmental data collection.

To be fair, the AqMood still does have its fair share of LEDs. In fact, one might even say it has several device’s worth of  them — the thirteen addressable LEDs that are run along the inside of the 3D printed diffuser will definitely get your attention. They’re sectioned off in such a way that each segment of the diffuser can indicate a different condition for detected levels of particulates, VOCs, and CO2.

But what really makes this project stand out is the 1.8 inch LCD mounted under the LEDs. This display is used to show various emojis that correspond with the current conditions. Hopefully you’ll see a trio of smiley faces, but if you notice a bit of side-eye, it might be time to crack a window. If you’d like a bit more granular data its possible to switch this display over to a slightly more scientific mode of operation with bar graphs and exact figures…but where’s the fun in that?

[Tobias] has not only shared all the files that are necessary to build your own AqMood, he’s done a fantastic job of documenting each step of the build process. There’s even screenshots to help guide you along when it’s time to flash the firmware to the XIAO Seeed ESP32-S3 at the heart of the AqMood.

If you prefer your air quality monitoring devices be a little less ostentatious, IKEA offers up a few hackable models that might be more your speed.

Custom Slimline CD Player Hides Out Under Speaker

March 27, 2025 by 10 Comments

In the era of digital streaming, the market is full of wireless speakers that will play content from your smartphone or pull it down from the Internet directly over WiFi. But if you’re feeling a bit nostalgic and want to throw on one of your old CDs, well, you might have a problem. That’s the situation [Chad Boughton] recently found himself in, so he decided to build a compact CD player that could discreetly connect up to his fancy Klipsch speaker.

The optical drive itself was the easy part, as [Chad] already had a laptop-style drive in an external enclosure that he could liberate. But of course, the speaker wouldn’t know what to do with an external disc drive, so there needed to be an intermediary. Enter the Raspberry Pi.

It might not look like it at first glance, but that’s a Pi 3 tucked into the back of the 3D printed frame. It would have been too tall in its original configuration, so [Chad] removed the USB and Ethernet ports; a modification we’ve covered in the past. Of course, he still needed to use the USB ports, so he ended up soldering the two cables — one to the CD drive and the other to the back of the speaker — directly to the Pi.

When plugged into the Raspberry Pi, the Klipsch speaker shows up as a USB audio device, so the software side of things was relatively simple. [Chad] installed VLC to handle CD playback, but he still needed a way to control everything. To that end, a IR receiver hooked up to the Pi’s GPIO pins means the Pi can detect the signals coming from the speaker’s original remote and pass the appropriate command on to VLC. The whole thing is very well integrated, and you could be forgiven for thinking it might be some kind of stock upgrade module at first glance.

Despite recently celebrating its 40th birthday, the CD is unlikely to completely disappear from our lives anytime soon. Manufacturers can turn their back on the standard if they want, but so long as folks still want to play them, they’ll keep coming up with inventive ways to make it happen.

Continue reading “Custom Slimline CD Player Hides Out Under Speaker” →

Rolling Foam Cutter Gives Mattress A Close Shave

March 24, 2025 by 19 Comments

There’s many different reasons why somebody might have to hack together their own solution to a problem. It could be to save money, or to save time. Occasionally it’s because the problem is unique enough that there might not be an accepted solution, so you’re on your own to create one. We think the situation that [Raph] recently found himself in was a combination of several of these aspects, which makes his success all the sweeter.

The problem? [Raph] had a pair of foam mattresses from his camper van that needed to be made thinner — each of the three inch (7.62 cm) pieces of foam needed to have one inch (2.5 cm) shaved off as neatly and evenly as possible. Trying to pull that off over the length of a mattress with any kind of manual tools was obviously a no-go, so he built a low-rider foam cutter.

With the mattresses laying on the ground, the idea was to have the cutter simply roll across them. The cutter uses a 45″ (115 cm) long 14 AWG nichrome wire that’s held in tension with a tension arm and bungee cords, which is juiced up with a Volteq HY2050EX 50 V 20 A variable DC power supply. [Raph] determined the current experimentally: the wire failed at 20 A, and cutting speed was too low at 12 A. In the end, 15 A seemed to be the sweet spot.

The actual cutting process was quite slow, with [Raph] finding that the best he could do was about 1/8″ (3 mm) per second on the wider of the two mattresses. While the result was a nice flat cut, he does note that at some point the mattresses started to blister, especially when the current was turned up high. We imagine this won’t be a big deal for a mattress though, as you can simply put that side on the bottom.

In the end, the real problem was the smell. As [Raph] later discovered, polyurethane foam is usually cut mechanically, as cutting it with a hot wire gives off nasty fumes. Luckily he had plenty of ventilation when he was making his cuts, but he notes that the mattresses themselves still have a stink to them a couple days later. Hopefully they’ll finish outgassing before his next camping trip.

As you can imagine, we’ve covered a great number of DIY foam cutters over the years, ranging from the very simple to computerized marvels. But even so, there’s something about the project-specific nature of this cutter that we find charming.

Acoustic Levitation Gets Insects Ready For Their Close-Up

March 22, 2025 by 6 Comments

The average Hackaday reader is likely at least familiar with acoustic levitation — a technique by which carefully arranged ultrasonic transducers can be used to suspend an object in the air indefinitely. It’s a neat trick, the sort of thing that drives them wild at science fairs, but as the technique only works on exceptionally small and light objects it would seem to have little practical use.

That is, unless, you happen to be interested in exceptionally small and light objects. A paper titled Automated Photogrammetric Close-Range Imaging System for Small Invertebrates Using Acoustic Levitation describes a fascinating device which allows the researchers to image insects in what’s essentially a weightless environment.

With the delicate specimens suspended in front of the lens, there’s no background to worry about and they can be perfectly lit from all angles. What’s more, with careful control of the ultrasonic transducers, it’s possible to control the rotation of the target — allowing researchers to produce 3D scans of the insects using just one camera.

There isn’t a whole lot of technical detail on the device itself, other than the fact that spherical chamber has a radius of 60 mm and is fitted with 96 Murata MA40S4R/S transducers operating at 40 kHz. The paper notes that early attempts to control the transducer array with a Arduino Mega failed, and that the team had to switch over to a FPGA. With their current signal generator stage, the researchers are able to rotate the specimen by 5° angles.

Interested in learning more about acoustic levitation? University of Bristol research scientist Asier Marzo gave a talk on the subject at Hackaday Belgrade in 2018 that you won’t want to miss.

PiEEG Kit Is A Self-Contained Biosignal Laboratory

March 20, 2025 by 9 Comments

Back in 2023, we first brought you word of the PiEEG: a low-cost Raspberry Pi based device designed for detecting and analyzing electroencephalogram (EEG) and other biosignals for the purposes of experimenting with brain-computer interfaces. Developed by [Ildar Rakhmatulin], the hardware has gone through several revisions since then, with this latest incarnation promising to be the most versatile and complete take on the concept yet.

At the core of the project is the PiEEG board itself, which attaches to the Raspberry Pi and allows the single-board computer (SBC) to interface with the necessary electrodes. For safety, the PiEEG and Pi need to remain electrically isolated, so they would have to be powered by a battery. This is no problem while capturing data, as the Pi has enough power to process the incoming signals using the included Python tools, but could be an issue if you wanted to connect the PiEEG system to another computer, say.

For the new PiEEG Kit, the hardware is now enclosed in its own ABS carrying case, which includes an LCD right in the lid. While you’ve still got to provide your own power (such as a USB battery bank), having the on-board display removes the need to connect the Pi to some other system to visualize the data. There’s also a new PCB that allows the connection of additional environmental sensors, breakouts for I2C, SPI, and GPIO, three buttons for user interaction, and an interface for connecting the electrodes that indicates where they should be placed on the body right on the silkscreen.

The crowdsourcing campaign for the PiEEG Kit is set to begin shortly, and the earlier PiEEG-16 hardware is available for purchase currently if you don’t need the fancy new features. Given the fact that the original PiEEG was funded beyond 500% during its campaign in 2023, we imagine there’s going to be plenty of interest in the latest-and-greatest version of this fascinating project.

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Relativity Space Changes Course On Path To Orbit

March 17, 2025 by 25 Comments

In 2015, Tim Ellis and Jordan Noone founded Relativity Space around an ambitious goal: to be the first company to put a 3D printed rocket into orbit. While additive manufacturing was already becoming an increasingly important tool in the aerospace industry, the duo believed it could be pushed further than anyone had yet realized.

Rather than assembling a rocket out of smaller printed parts, they imagined the entire rocket being produced on a huge printer. Once the methodology was perfected, they believed rockets could be printed faster and cheaper than they could be traditionally assembled. What’s more, in the far future, Relativity might even be able to produce rockets off-world in fully automated factories. It was a bold idea, to be sure. But then, landing rockets on a barge in the middle of the ocean once seemed pretty far fetched as well.

An early printed propellant tank.

Of course, printing something the size of an orbital rocket requires an exceptionally large 3D printer, so Relativity Space had to built one. It wasn’t long before the company had gotten to the point where they had successfully tested their printed rocket engine, and were scaling up their processes to print the vehicle’s propellant tanks. In 2018 Bryce Salmi, then an avionics hardware engineer at Relatively Space, gave a talk at Hackaday Supercon detailing the rapid progress the company had made so far.

Just a few years later, in March of 2023, the Relativity’s first completed rocket sat fueled and ready to fly on the launch pad. The Terran 1 rocket wasn’t the entirely printed vehicle that Ellis and Noone had imagined, but with approximately 85% of the booster’s mass being made up of printed parts, it was as close as anyone had ever gotten before.

The launch of Terran 1 was a huge milestone for the company, and even though a problem in the second stage engine prevented the rocket from reaching orbit, the flight proved to critics that a 3D printed rocket could fly and that their manufacturing techniques were sound. Almost immediately, Relativity Space announced they would begin work on a larger and more powerful successor to the Terran 1 which would be more competitive to SpaceX’s Falcon 9.

Now, after an administrative shakeup that saw Tim Ellis replaced as CEO, the company has released a nearly 45 minute long video detailing their plans for the next Terran rocket — and explaining why they won’t be 3D printing it.

Continue reading “Relativity Space Changes Course On Path To Orbit” →