Ploopy Builds Open Source RP2040-Powered Headphones And You Can Too!

February 15, 2023 by Dave Rowntree 16 Comments

We’ve seen many DIY headphones projects on these fair pages over the years, but not many that are quite as DIY as the Ploopy Headphones. What makes this project interesting is the sheer depth of the construction, with every single part being made from what we might call base materials. Materials such as 3D printer filament, foam and felt, and the usual metallic vitamins.

The electronics are fairly straightforward, with an RP2040 functioning as the USB audio interface and equalizer function. Audio samples are emitted as I²S into a PCM3050 24-bit stereo codec which generates a pair of differential output audio signals. These are then converted from differential to single-ended signals and passed on to the coil drivers. The coil drivers consist of no fewer than eight-paralleled opamps per channel. All of this is powered by the USB-C connection to the host computer. Whilst a kit of parts is available for this, you can make your own if you wish, as the full source (Altium designer needed for tweaks) is available on the Ploopy headphone GitHub.

Many DIY headphone builds would likely be using off-the-shelf speaker units, with large parts of the ear cups being taken from spare parts kits for commercial offerings. But not the Ploopy. The drivers are constructed from flex PCB coils with a standard TRRS jack on each side. Magnets for these coils to react against are held in a 3D-printed frame that is attached to the outer cover. The coils are aligned with a special jig and bonded to the ‘driver foam’ with some 3M VHB tape.

The ear cups are constructed with some 3D printed rings, foam pieces, and simple woven material. The resonator plates push into the inner side of the cup, and the assembly simply screws to the driver assembly. The incredibly detailed assembly wiki makes it look easy, but we reckon there are a few tricky steps in there to trip the unwary. The headband again consists of printed spring sections, some woven material, and foam with a few metallic vitamins thrown in. That makes it sounds simple, but it isn’t.

On the whole the build looks fantastic, but what does it sound like? The Ploopy team has tested them against a pair of Sennheiser HDRXX giving a broadly comparable response, but we’re no audio experts, and the proof, as always, is in the wearing. This project seems to be the ultimate in audio tweakability, with the punchy RP2040 capable of running six audio filters at the full 48 KHz, 16-bit audio, though, the PCM3050 is capable of more.

Want to build some headphones, but need a Bluetooth interface? We got you covered. Can 3D printed headphones ever compare to the big names? We’ll see.

Electronic Shoe Explores Alleged Chess Misbehavior

February 1, 2023 by Bryan Cockfield 20 Comments

A few months ago, a scandal erupted in the chess world which led to some pretty wild speculation around a specific chess player. We won’t go into any of the details except to say that there is virtually no physical evidence of any method this player allegedly used to cheat in a specific in-person chess match. But [Teddy Warner] and partner [Jack Hollingsworth] were interested in at least providing a proof-of-concept for how this cheating could have been done, though, and came up with this device which signals a chess player through a shoe.

The compact device is small enough to fit in the sole of one of the player’s shoes, and is powered by an ATtiny412 microcontroller paired with a HC-06 Bluetooth module. The electronics are fitted into a 3D printed case along with a small battery which can then be placed into the sole of a shoe, allowing the wearer to feel the vibrations from a small offset-weight motor. With a second person behind a laptop and armed with a chess engine, the opponent’s moves can be fed into the computer and the appropriate response telegraphed through the shoe to the player.

While [Teddy] and [Jack] considers the prototype a success in demonstrating the ease at which a device like this could be used, and have made everything related to this build open source, this iteration did have a number of issues including that the motor buzzing was noticeable during play, and that his chess engine made some bizarre choices in the end game. It also requires the complicity of a second person, which is something this other chess cheating machine does away with. They also note that it’s unlikely that any chess players at the highest levels use devices like these, and that other chess experts have found no evidence of any wrongdoing in this specific scandal.

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Supercon 2022: Sophy Wong Is Making An Impact With Artistic Wearables

January 25, 2023 by Kristina Panos 5 Comments

Prolific designer and maker Sophy Wong is always looking toward the future, and that goes for everything from the costume pieces she makes to the idea of making itself. In her excellent and highly-visual Supercon talk, Sophy explores both, and gives the viewer a window on her evolved-and-evolving design philosophy.

You likely know Sophy as That Maker Who 3D Prints On Fabric, a label she is quick to dismiss, pointing animatedly toward the seminal work of one David Shorey, who also happened to be at Supercon 2022. As Sophy explains, the process begins by modeling disconnected bodies to be printed, then printing the first layer and pausing the print. At this point, a piece of nylon mesh is inserted, and the print is resumed. The result is that the mesh is trapped between the first and second layers, and the bodies are now connected by a common thread. Carefully remove the sandwich from the print bed and you have a highly-flexible, mesmerizing piece of material that almost acts like chain maille.

Continue reading “Supercon 2022: Sophy Wong Is Making An Impact With Artistic Wearables” →

ZSWatch: This OSHW Smart Watch Is As DIY As It Gets

January 16, 2023 by Tom Nardi 17 Comments

We say it often, but it’s worth repeating: this is the Golden Age of making and hacking. Between powerful free and open source software, low-cost PCB production, and high resolution 3D printers that can fit on your desk, a dedicated individual has everything they need to make their dream gadget a reality. If you ever needed a reminder of this fact, just take a look at the ZSWatch.

When creator [Jakob Krantz] says he built this MIT-licensed smart watch from scratch, he means it. He designed the 4-layer main board, measuring just 36 mm across, entirely in KiCad. He wrote every line of the firmware, and even designed the 3D printable case himself. This isn’t some wearable development kit he got off of AliExpress and modified — it’s all built from the ground up, and all made available to anyone who might want to spin up their own version.

The star of the show is the nRF52833 SoC, which is paired with a circular 1.28″ 240×240 IPS TFT display. The screen doesn’t support touch, so there’s three physical buttons on the watch for navigation. Onboard sensors include a LIS2DS12 MEMS accelerometer and a MAX30101EFD capable of measuring heartrate and blood oxygen levels, and there’s even a tiny vibration motor for haptic feedback. Everything’s powered by a 220 mAh Li-Po battery that [Jakob] says is good for about two days — afterwards you can drop the watch into its matching docking station to get charged back up.

As for the software side of things, the watch tethers to a Android application over Bluetooth for Internet access and provides the expected functions such as displaying the weather, showing notifications, and controlling music playback. Oh, and it can tell the time as well. The firmware was made with extensibility in mind, and [Jakob] has provided both a sample application and some basic documentation for would-be ZSWatch developers.

While an unquestionably impressive accomplishment in its current form, [Jakob] says he’s already started work on a second version of the watch. The new V2 hardware will implement an updated SoC, touch screen, and an improved charging/programming connector. He’s also looking to replace the 3D printed case for something CNC milled for a more professional look.

The ZSWatch actually reminds us quite a bit of the Open-SmartWatch project we covered back in 2021, in that the final result looks so polished that the average person would never even take it for being DIY. We can’t say that about all the smartwatches we’ve seen over the years, but there’s no question that the state-of-the-art is moving forward for this kind of thing in the hobbyist space.

Sensor Glove Translates Sign Language

January 13, 2023 by Lewin Day 17 Comments

Sign language is a language that uses the position and motion of the hands in place of sounds made by the vocal tract. If one could readily capture those hand positions and movements, one could theoretically digitize and translate that language. [ayooluwa98] built a set of sensor gloves to do just that.

The brains of the operation is an Arduino Nano. It’s hooked up to a series of flex sensors woven into the gloves, along with an accelerometer. The flex sensors detect the bending of the fingers and the gestures being made, while the accelerometer captures the movements of the hand. The Arduino then interprets these sensor signals in order to match the user’s movements up with a pre-stored list of valid signs. It can then transmit out the detected language via a Bluetooth module, where it is passed to an Android phone for translation via text-to-speech software.

The idea of capturing sign language via hand tracking is a compelling one; we’ve seen similar projects before, too. Meanwhile, if you’re working on your own accessibility projects, be sure to drop us a line!

Walk-Bot Is A Navigation Device For The Vision-Impaired

January 11, 2023 by Lewin Day 11 Comments

For the vision impaired, there are a wide variety of tools and techniques used to navigate around in the real world. Walk-bot is a device that aims to help with this task, using ultrasound to provide a greater sense of obstacles in one’s surroundings.

Is trigonometry the most useful high school maths out there? There’s an argument that says yes.

Created by [Nilay Roy Choudhury], the device is intended to be worn on the waist, and features two sets of ultrasonic sensors. One set is aimed straight ahead, while the other points upwards at an angle of 45 degrees. An infrared sensor then points downward at an angle of 45 degrees, aimed at the ground.

The distance readings from these sensors are then collated by a microcontroller, which uses trigonometry to determine the user’s actual distance to the object. When objects are closer than a given threshold, the device provides feedback to the user via a buzzer and a vibration motor. The combination of three sensors looking out at different angles helps capture a variety of obstacles, whether they be at head, chest, or knee height.

It’s unlikely that a complex electronic device would serve as a direct replacement for solutions like the tried-and-tested cane. However, that’s not to say there isn’t value in such tools, particularly when properly tested and designed to suit user’s needs.

We’ve seen some great projects regarding visual impairment before, like this rig that allows users to fly in a simulator. If you’ve been working on your own accessibility tools, don’t hesitate to drop us a line!

pulse oximeter as a small sticker that sticks on your fingernail and measures heart rate, motion, and blood oxygen

This Fingernail Sticker Can Detect When You Stop Breathing

January 1, 2023 by Orlando Hoilett 8 Comments

Sometimes we dig through the archives to see what kind of crazy hacks we can pull out of the depths of the world wide web and this one was worth sharing. Researchers at Northwestern University developed a sticker that’s applied to the fingernail and measures heart rate, motion, and blood oxygen, all without a battery.

The photoplethysmograph (PPG) system is similar to what we’ve covered before and the motion sensor is simply an accelerometer, so we won’t go over those aspects of the device. The parts of the device that did catch our attention were the battery-less operation as well as its size. It’s just so dang small! And fits snuggly on a fingernail or on even on your earlobe. The size here is actually a very interesting feature and not just a marketing plug. Because the device is so small and lightweight, it is very easy to adhere to the fingernail or skin with very little sensory perception. Basically, the person wearing the device won’t even notice it’s there. That’s definitely an advantage over the traditional, bulky, hospital-grade instruments we’ve grown accustomed to.

The device adheres really well given its small and lightweight design, so motion artifacts are significantly reduced. Motion artifacts in PPG-based devices are due to the relative motion between the optode (LED and photodiode) and the skin. The traditional approaches of ensuring the device don’t move are for the patient to keep very still during a recording, to wear the device tightly against the skin (think of how tightly you need to wear your smartwatch to get consistent readings), or use some seriously tough and uncomfortable adhesive as you may have done if you’ve ever gotten an electrocardiogram reading before. This device eliminates those three problems.

The other aspect of the device that caught our attention is its use of wireless power instead of a battery. In some senses, this could be seen as an advantage or as a disadvantage. The device relies on NFC for power and data transmission, a pretty common approach for devices that only need to be used intermittently. Wireless power could be a bit problematic for continuous monitoring devices which provide readings every second or several times a second. But who knows, wireless power seems to be everywhere these days.

Digging into the details a bit, the double-layer antenna is designed around the circumference of the device using wet etching to create traces on a copper polyimide foil. The team electroplated holes through the different layers of the device (optode layer, first antenna layer, polyimide, second antenna layer, component layer, protective top coat) connecting the antenna to the die pad NFC chip (SL13A, AMS AG). Connecting the chip requires some pretty fine-pitch soldering techniques, but nothing we’re not accustomed to here at Hackaday. Overall, they seemed pretty successful, obtaining a Q factor of 16 and a transmission distance of 30 mm using a smartphone and not some giant reader antenna.

Definitely, a really cool project that we recommend checking out.