Over the last few years, it’s been increasingly common for concertgoers to be handed a light-up bracelet from PixMob that synchronizes with the others in the crowd to turn the entire audience into a music visualizer. They’re a clever way of enhancing the concert experience, but unfortunately, they don’t do anything once you leave the show. Or at least, that used to be the case.

We’ve seen efforts to reverse engineer the IR (and occasionally radio) signals that drive these PixMob devices, but since we checked in last it seems like things have gotten a lot easier for the home gamer. [David Pride] has recently posted a brief write-up that shows how quickly and easily it is to get these devices fired up using nothing more exotic than an Arduino, an IR LED, and an audio sensor module.

With the audio sensor module connected to the Arduino’s digital input and the IR LED wired to digital out, all you need to do is flash firmware to the board and start playing some beats. The source code [David] has provided is a a remixed version of what’s previously been published by [Carlos Ganoza], which, in this case, has been tweaked to make the lighting patterns less random.

Presumably, this is to make the devices behave more like they do during an actual concert, but since nobody at Hackaday is cool enough to have seen a live musical performance in the last decade, we’re not really sure. All we can say is that the effect looks pretty sweet in the demo video.

Back in 2019, we saw a teardown of an early PixMob device, and by 2022, the efforts to reverse engineer their IR control protocol were well underway. We’re glad to see things have progressed to the point that you can piece together a transmitter from what’s in the parts bin, as it means at least some of these devices will have a lifespan longer than a single concert.

It’s a constant battle for musicians — how to practice your instrument without bothering those around you? Many of us live in apartments or shared accommodation, and having to wait until the apartment is empty or only being able to practice at certain times of day can be restrictive, especially if you need to practice for an upcoming gig or if the creative juices start flowing and it’s 3 AM! [Gavin] was having this issue and started developing Porter, a guitar/bass practice device which works with all effects pedals and is portable and rechargeable. So you can grind away your epic heavy metal solo no matter the time of day!

While there have been similar solutions, many musicians weren’t satisfied with the sound and often couldn’t support inputs from distortion pedals. They usually chewed through batteries and were just not a great solution to the problem. [Gavin] has spent the last two years fine-tuning the design. It’s a fully analog design, with built-in rechargeable batteries to boot. So it not only sounds great, but it can last as long as your practice session does with a 15-hour runtime when fully charged!

Initially, the project began as a headphone amplifier but morphed into a design specifically for guitar and bass, with preamp and power amp stages and adjustable input impedance – 500kΩ for guitars and 1MΩ for bass. The latest revision also changed to a different power amp that further reduced THD and led to an even better sound. The schematics are up on the Hackaday.io project page, but [Gavin] is also hoping to do a crowdfunding campaign to get these devices out into the hands of guitarists everywhere!

Craig Lindley is a technical author and a prolific maker of things. This simple project was his first attempt to create a laser harp MIDI device. While on vacation, Craig saw a laser harp with only three strings and decided to improve upon it by expanding it to twelve strings. The principle of operation is straightforward: twelve cheap diode laser modules aim a beam towards an LDR, which changes resistance if the light level changes when the beam is interrupted.

The controller is a simple piece of perf board, with a Wemos D1 mini ESP32 module flanked by some passives, a barrel socket for power, and the usual DIN connector for connecting the MIDI instrument. Using the ESP32 is a smart choice, removing all the need for configuration and user indication from the physical domain and pushing it onto a rarely-needed webpage. After a false start, attempting to use a triangular frame arrangement, [Craig] settled upon a simple linear arrangement of beams held within a laser-cut wooden box frame. Since these laser modules are quite small, some aluminium rod was machined to make some simple housings to push them into, making them easier to mount in the frame and keeping them nicely aligned with their corresponding LDR.

Sadly, the magnetic attachment method [Craig] used to keep the LDRs in place and aligned with the laser didn’t work as expected, so it was necessary to reach for the hot glue. We’ve all done that!

An interesting addition was using an M5 stack Unit-Synth module for those times when a proper MIDI synthesiser was unavailable. Making this luggable was smart, as people are always fascinated with laser harps. That simple internal synth makes travelling to shows and events a little easier.

Laser harps are nothing new here; we have covered plenty over the years. Like this nice build, which is more a piece of art than an instrument, one which looks just like a real harp and sounds like one, too, due to the use of the Karplus-Strong algorithm to mimic string vibrations.

Synth designers [Erica Synths] have devised a very cool, approachable way to get started with DIY synth hacking. Designed around a breadboard, the EDU DIY LABOR is a synth module with everything you need to get started. The Basic version comes with potentiometers, switches, and jack sockets, and is aimed more at those who likely already have a decent supply of parts on hand for experimentation. The Full kit comes with all that, plus a supply of resistors, capacitors, ICs and transistors so you can get up to speed, even as a beginner.

The device is supplied as a semi-DIY kit, with some soldering and assembly required. The kit was designed in collaboration with Dr. Shalom D. Ruben, a teaching professor of engineering at the University of Colorado. So it should be approachable for those with some soldering experience under their belt. Labor includes a multi-voltage power supply which supplies all Eurorack voltages, an oscillator section for both audible ranges and LFO, a full envelope control section, an output amplifier and more! Once assembled you can quickly start making bloops, beeps, and bzzts. You can easily design filters, oscillators, amplifiers, sequencers, and whatever else you can dream up!

However, the kit is designed to be more than just a synth playground – the idea was also to create an environment where you could learn the basics of electronics at the same time, in an approachable, fun way. This is reflected in the excellent user manual, which goes beyond just assembling the device and gives some example circuits, complete with wave diagrams and detailed working explanations. Great for beginners and experienced hackers who want to learn more about fundamentals and audio synthesis!

The Marimbatron is [Leo Kuipers] ‘s final project as part of the Fab Academy program supervised by [Prof. Neil Gershenfeld] of MIT’s Center for Bits and Atoms. The course aims to teach students how to leverage all the fab lab skills to create unique prototypes using the materials at hand.

Fortunately, one of the main topics covered in the course is documentation, and [Leo] has provided ample material for review. The marimba consists of a horizontal series of wooden bars, each mounted over a metal resonator tube. It is played similarly to the xylophone, with a piano-type note arrangement, covering about five octaves but with a lower range than the xylophone. [Leo] converted this piano-type layout into a more logical grid arrangement. The individual pads are 3D printed in PETG and attached to a DIY piezoresistive pressure sensor made from a graphite-sprayed PET sheet laid upon a DIY flexible PCB. A central addressable LED was also included for indication purposes. The base layer is made of cast polyurethane, formed inside a 3D-printed rigid mould. This absorbs impact and prevents crosstalk to nearby sensors. The sensor PCB was initially prototyped by adhering a layer of copper tape to a layer of Kapton tape and cutting it out using a desktop vinyl cutter. While this method worked for the proof of concept, [Leo] ultimately outsourced the final version to a PCB manufacturer. The description of prototyping the sensor and dealing with over-moulding was particularly fascinating.

For the electronics, a modular approach was needed. Each row of ten sensors was daisy-chained to connect the LEDs, with an individual sense line passed down for each sensor to a common sensor PCB. This uses a SAMD21-series microcontroller with enough ADC channels to handle the task. This was initially prototyped using a micro-milled PCB and a laser-cut PET solder stencil. Once that was proven to work well, the sensible thing was done, and the final PCBs were ordered from a proper fab. Additionally, a user interface PCB was created to host a few pushbuttons and a Waveshare round LCD display. Finally, a main control PCB routes I²C to the sensor boards and interfaces to the SPI LCD. It also handles sending MIDI data over USB for playback on an external MIDI device.

Documentation and design data can both be found on the project fabcloud page. To dig into the Fab Academy courses, wander over to the course archive and get cracking.

This is the first marimba we’ve covered, so here’s a mechanical xylophone instead. Whilst we’re on the subject of mechanical music, here’s a fun one to go back over.

There’s no shortage of devices out there for creating electronic music, but if you’re just looking to get started, the prices on things like synthesizers and drum machines could be enough to give you second thoughts on the whole idea. But if you’ve got a well stocked parts bin, there’s a good chance you’ve already got most of what you need to build your own Crunch-E.

Described by creator [Roman Revzin] as a “keychain form factor music-making platform”, the Crunch-E combines an ESP32, an MAX98357 I2S audio amplifier, an array of tactile buttons, and a sprinkling of LEDs and passives. It can be built on a perfboard using off-the-shelf modules, or you can spin up a PCB if you want something a bit more professional. It sounds like there’s eventually going to be an option to purchase a pre-built Crunch-E at some point as well.

But ultimately, the hardware seems to be somewhat freeform — the implementation isn’t so important as long as you’ve got the major components and can get the provided software running on it.

The software, which [Roman] is calling CrunchOS, currently provides four tracks, ten synth instruments, and two drum machine banks. Everything can be accessed from a 4 x 4 button array, and there’s a “cheat sheet” in the documentation that shows what each key does in the default configuration. Judging by the demo video below, it’s already an impressively capable platform. But this is just the beginning. If everything goes according to plan and more folks start jamming on their own Crunch-E hardware, it’s not hard to imagine how the software side can be expanded and adapted over time.

Over the years we’ve seen plenty of homebrew projects for producing electronic music, but the low-cost, simple construction, and instant gratification nature of the Crunch-E strikes us as a particularly compelling combination. We’re eager to see where things develop from here.

Historically speaking, optional peripherals for game consoles tend not to be terribly successful. You’ll usually get a handful of games that support the thing, one of which will likely come bundled with it, and then the whole thing fades into obscurity to make way for the next new gimmick.

For example, did you know Nintendo offered a pair of bongos for the GameCube in 2003? They were used almost exclusively by the trio of Donkey Konga rhythm games, although only two of them were ever released outside of Japan. While the games might not have been huge hits, they were successful enough to stick in the memory of [bl3i], who wanted a way to keep the DK bongo experience alive.

The end result is, arguably, more elegant than the hokey musical controller deserves. While most people would have just gutted the plastic bongos and crammed in some new hardware, [bl3i] went through considerable effort so the original hardware would remain intact. His creation simply snaps onto the bongos and connects to them via the original cable.

Internally, the device uses an Arduino to read the output of the bongos (which appeared to the GameCube essentially as a standard controller) and play the appropriate WAV files from an SD card as hits are detected. Add in an audio amplifier module and a battery, and Nintendo’s bongos can finally go forth into the world and spread their beats.

As far as we’re able to tell, this is the first time the Donkey Kong bongos have ever graced the pages of Hackaday in any form, so congratulations to [bl3i] for getting there first. But it’s certainly not the first time we’ve covered ill-conceived game gadgets — long time readers will perhaps be familiar with Nintendo’s attempt to introduce the Robotic Operating Buddy (ROB) to households back in 1985.

What was the worst thing about the 70s? Some might say the oil crisis, inflation, or even disco. Others might tell you it was 8-track tapes, no matter what was on them. I’ve heard that the side of the road was littered with dead 8-tracks. But for a while, they were the only practical way to have music in the car that didn’t come from the AM/FM radio.

If you know me at all, you know that I can’t live without music. I’m always trying to expand my collection by any means necessary, and that includes any format I can play at home. Until recently, that list included vinyl, cassettes, mini-discs, and CDs. I had an 8-track player about 20 years ago — a portable Toyo that stopped working or something. Since then, I’ve wanted another one so I can collect tapes again. Only this time around, I’m trying to do it right by cleaning and restoring them instead of just shoving them in the player willy-nilly.

Update: I Found a Player

A couple of weeks ago, I was at an estate sale and I found a little stereo component player and speakers. There was no receiver in sight. I tested the player with the speakers and bought them for $15 total because it was 75% off day and they were overpriced originally. While I was still at the sale, I hooked it up to the little speakers and made sure it played and changed programs.

Well, I got it home and it no longer made sound or changed programs. I thought about the play head inside and how dirty it must be, based on the smoker residue on the front plate of the player. Sure enough, I blackened a few Q-tips and it started playing sweet tunes again. This is when I figured out it wouldn’t change programs anymore.

I found I couldn’t get very far into the player, but I was able to squirt some contact cleaner into the program selector switch. After many more desperate button presses, it finally started changing programs again. Hooray!

I feel I got lucky. If you want to read about an 8-track player teardown, check out Jenny List’s awesome article.

These Things Are Not Without Their Limitations

So now, the problem is the tapes themselves. I think there are two main reasons why people think that 8-tracks suck. The first one is the inherent limitations of the tape. Although there were 90- and 120-minute tapes, most of them were more like 40-60 minutes, divided up into four programs. One track for the left channel, one for the right, and you have your eight tracks and stereo sound.

The tape is in a continuous loop around a single hub. Open one up and you’ll see that the tape comes off the center toward the left and loops back onto the outside from the right. 8-tracks can’t be rewound, only fast-forwarded, and it doesn’t seem like too many players even had this option. If you want to listen to the first song on program one, for instance, you’d better at least tolerate the end of program four.

The tape is divided into four programs, which are separated by a foil splice. A sensor in the machine raises or lowers the playback head depending on the program to access the appropriate tracks (1 and 5, 2 and 6, and so on.)

Because of the 10-12 minute limitation of each program, albums were often rearranged to fit better within the loud solenoidal ka-chunk of each program change.

For a lot of people, this was outright heresy. Then you have to consider that not every album could fit neatly within four programs, so some tracks faded out for the program change, and then faded back in, usually in the middle of the guitar solo.

Other albums fit into the scheme with some rearrangement, but they did so at the expense of silence on one or more of the programs. Check out the gallery below to see all of these conditions, plus one that divided up perfectly without any continuations or silence.

The second reason people dislike 8-tracks is that they just don’t sound that good, especially since cassette tapes were already on the market. They didn’t sound super great when they were new, and years of sitting around in cars and dusty basements and such didn’t help. In my experience, at this point, some sound better than others. I suppose after the tape dropout, it’s all subjective.

What I Look For When Buying Tapes

The three most important things to consider are the pressure pads, the foil splices, and the pinch roller. All of these can be replaced, although some jobs are easier than others.

Start by looking at the pressure pads. These are either made of foam that’s covered with a slick surface so the tape can slide along easily, or they are felt pads on a sproingy metal thing like a cassette tape. You want to see felt pads when you’re out shopping, but you’ll usually see foam. That’s okay. You can get replacement foam on ebay or via 8-track avenue directly, or you can do what I do.

After removing the old foam and scraping the plastic backing with my tweezers, I cut a piece of packing tape about 3/8″ wide — just enough to cover the width of some adhesive foam window seal. The weatherstripping’s response is about the same as the original foam, and the packing tape provides a nice, slick surface. I put a tiny strip of super glue on the adhesive side and stick one end down into the tape, curling it a little to rock it into position, then I press it down and re-tension the tape. The cool part is that you can do all this without opening up the tape by just pulling some out. Even if the original foam seems good, you should go ahead and replace it. Once you’ve seen the sticky, black powder it can turn to with time, you’ll understand why.

Another thing you can address without necessarily opening up the tape are the foil splices that separate the programs. As long as the pressure pads are good, shove that thing in the player and let it go until the ka-chunk, and then pull it out quickly to catch the splice. Once you’ve got the old foil off of it, use the sticky part of a Post-It note to realign the tape ends and keep them in place while you apply new foil.

Again, you can get sensing foil on ebay, either in a roll, or in pre-cut strips that have that nice 60° angle to them. Don’t try to use copper tape like I did. I’ll never know if it worked or not, because I accidentally let too much tape un-spool from the hub while I was splicing it, but it seemed a little too heavy. Real-deal aluminium foil sensing tape is even lighter-weight than copper tape.

One thing you can’t do without at least opening the tape part way is to replace the pinch roller. Fortunately, these are usually in pretty good shape, but you can usually tell right away if they are gooey without having to press your fingernail into it. Even so, I have salvaged the pinch rollers out of tapes I have tried to save and couldn’t, just to have some extras around.

If you’re going to open the tape up, you might as well take some isopropyl alcohol and clean the graphite off of the pinch roller. This will take a while, but is worth it.

Other Problems That Come Up

Sometimes, you shove one of these bad boys in the player and nothing happens. This usually means that the tape is seized up and isn’t moving. Much like blowing into an N64 cartridge, I have heard that whacking the tape on your thigh a few times will fix a seized tape, but so far, that has not worked for me. I have so far been unable to fix a seized tape, but there are guides out there. Basically, you cut the tape somewhere, preferably at a foil splice, fix the tension, and splice it back together.

Another thing that can happen is called a wedding cake. Basically, you open up the cartridge and find that the inner loops of tape have raised up around the hub, creating a two-layer effect that resembles a wedding cake. I have not so far successfully fixed such a situation, but I’ve only run across one so far. Basically, you pull the loops off of the center, re-tension the tape from the other side, and spin those loops back into the center. This person makes it look insanely easy.

Preventive Maintenance On the Player

As with cassette players, the general sentiment is that one should never actually use a head-cleaning tape as they are rough. As I said earlier, I cleaned the playback head thoroughly with 91% isopropyl alcohol and Q-tips that I wished were longer.

Another thing I did to jazz up my discount estate sale player was to make a capstan-cleaning tape per these instructions on 8-Track Avenue. Basically, I took my poor Dionne Warwick tape that I couldn’t fix, threw away the tape, kept the pinch roller for a rainy day, and left the pressure pads intact.

To clean the capstan, I took a strip of reusable dishrag material and stuffed it in the place where the pinch roller goes. Then I put a few drops of alcohol on the dishrag material and inserted the tape for a few seconds. I repeated this with new material until it came back clean.

In order to better grab the tape and tension it against the pinch roller, the capstan should be roughed up a bit. I ripped the scrubby side off of an old sponge and cut a strip of that, then tucked it into the pinch roller pocket and let the player run for about ten seconds. If you listen to a lot of tapes, you should do this often.

Final Thoughts

I still have a lot to learn about fixing problematic 8-tracks, but I think I have the basics of refurbishment down. There are people out there who have no qualms about ironing tapes that have gotten accordioned, or re-spooling entire tapes using a drill and a homemade hub-grabbing attachment. If this isn’t the hacker’s medium, I don’t know what is. Long live 8-tracks!

Anyone who first experienced music on computers using Winamp probably shares a memory of seeing that classic UI for the first time. Everything about it was a step ahead of the clunky, chunky interfaces we were used to, and even though it was supposed to be unobtrusive, it was hard to tear your eyes off that silky-smooth spectrum analyzer bouncing out your favorite MP3s.

Recapturing a little of the Winamp magic is the goal of Linamp, an physical version of the classic media player. It reproduces the Winamp UI on a touchscreen LCD with a wide aspect ratio that almost perfectly matches the original layout. Behind the display is a Raspberry Pi 4 with a 32 GB SD card, with all the important connections brought out to a board on the back of the case. The case itself is a treat, as it borrows design elements from another bit of retro gear, the mini-rack audio systems that graced many a bookshelf in the 1980s — and powered many high school parties too, if memory serves.

To recreate the case, [Rodmg] designed a sheet metal case and had it custom-made from anodized aluminum by PCBWay. He also printed a bezel for the display that looks very similar to the Winamp window border, complete with control icons. Where the build really shines, though, is with the work [Rodmg] put into the software. He matched the original Winamp UI very closely, both in terms of layout and performance. The pains he went to to get the spectrum analyzer working, including a deep dive into FFT, are impressive.

The results speak for themselves on this one, and hats off to [Rodmg] for the effort and the ride on the nostalgia train. We don’t know if the recent announcement of Winamp’s impending open-sourcing will have much impact on this project, but it might result in a flood of new Winamp builds.

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.

Are you tired of the same old music, but can’t afford any new tunes, even if they’re on dead formats? Boy, do we know that feeling. Here’s what you do: build yourself a GlobeTune music player, and you’ll never want for new music again.

The idea is simple, really. Just turn what we assume is a nice, clicky knob, and after a bit of static (which is a great touch!), you get a new, random radio station from somewhere around the globe. [Alexis D.] originally built this as a way to listen to and discover new music while disconnecting from the digital world, and we think it’s a great idea.

[Alexis D.] has production in mind, so after a Raspberry Pi Zero W prototype, they set about redesigning it around the ESP32. The current status seems to be hardware complete, software forthcoming. [Alexis D.] says that a crowdfunding campaign is in the works, but that the project will be open-sourced once in an acceptable state. So stay tuned!

Speaking of dead-ish formats, here’s an Internet radio in a cassette form factor.

Pianos traditionally had keys made out of ivory, but there’s a great way to avoid that if you want to save the elephants. You can build a keyboard using spoons, as demonstrated by [JCo Audio]. 

The build relies on twelve metal spoons to act as the keys of the instrument. They’re assembled into a wooden base in a manner roughly approximating the white and black keys of a conventional piano keyboard, using 3D-printed inserts to hold them in place. They’re hooked up to a Raspberry Pi Pico via a Pico Touch 2 board, which allows the spoons to be used as capacitive touch pads. Code from [todbot] was then used to take input from the 12 spoons and turn it into MIDI data. From there, hooking the Pi Pico up to a PC running some kind of MIDI synth is enough to make sounds.

It’s a simple build, but a functional one. Plus, it lets you ask your friends if they’d like to hear you play the spoons. The key here is to make a big show of hooking your instrument up to a laptop while explaining you’re not going to play the spoons a la the folk instrument, but you’re going to play a synth instead. Then you should use the spoon keyboard to play emulated spoon samples anyway. It’s called doubling down. Video after the break.

Creating music in 2024 is made easier by ready access to a host of effects in software that were once the preserve only of professional studios. One such is the delay; digital delays are now a staple of any production software where once they required infrastructure. [Look Mum No Computer] is no stranger to the world of Lo-Fi analogue music making, and along with his musical collaborator [Hainback], he’s created an analogue delay from an unexpected material: garden hose pipe.

The unit takes inspiration from some commercial 1970s effects, and lends a fixed short delay intended to give a double-tracking effect to vocals or similar. It involves putting a speaker at one end of a reel of hose and a microphone at the other, while the original unexpectedly used Shure SM57 capsules as both speaker and microphone they use a very small loudspeaker and a cheap microphone capsule.

The sound is not what you’d call high quality. Indeed, it’s about what one might expect when listening down a long pipe. But when mixed in behind the vocals, it gives a very pleasing effect. The duo use it on their new EP which, as you might expect, is released on vinyl.

If such effects interest you, also take a look at a 1950s reverb room at the famous Abbey Road Studios in London.

Have you ever wanted to take a break from reading or studying to just rock out for a few blissful minutes? If you’re anything like us, you like to rock out most of the time and take the occasional break to do your reading. Either way, you really can’t go wrong with this MIDI bookmark from [Misfit Maker].

This slick little bookmark may look 3D printed, but it’s all carefully-cut foam board in two thicknesses. Even the keys are made foam board — they’re just wrapped in carbon fiber so they look extra cool.

Underneath that carbon fiber is a layer of aluminium tape to make them capacitive. [Misfit Maker] recommends using copper tape instead because it allows for wires to be soldered directly to the keys.

The brains of this beauty is in the form of an ESP32 which is controlling an MPR-121 capacitive touch sensor. If you’d like to make one of these for yourself, there are plenty of helpful GIFs embedded in the thorough write-up. Be sure to check out the brief demo after the break.

If you want to easily MIDI-fy something and use touch inputs, you can’t really go wrong with the Raspberry Pi Pico, which does capacitive touch natively. Check out this MIDI kalmiba to learn more.

NASA astronaut [Don Pettit] shared a short video from an experiment he performed on the ISS back in 2012, demonstrating the effects of sound waves on water in space. Specifically, seeing what happens when a sphere of water surrounding an air bubble perched on a speaker cone is subjected to a variety of acoustic waves.

The result is visually striking patterns across different parts of the globe depending on what kind of sound waves were created. It’s a neat visual effect, and there’s more where that came from.

[Don] experimented with music as well as plain tones, and found that cello music had a particularly interesting effect on the setup. Little drops of water would break off from inside the sphere and start moving around the inside of the air bubble when cello music was played. You can see this in action as part of episode 160 from SmarterEveryDay (cued up to 7:51) which itself is about exploring the phenomenon of how water droplets can appear to act in an almost hydrophobic way.

This isn’t the first time water and sound collide in visually surprising ways. For example, check out the borderline optical illusion that comes from pouring water past a subwoofer emitting 24 Hz while the camera captures video at 24 frames per second.

We’ve all seen a million videos online with singing Tesla coils doing their thang. [Zach Armstrong] wasn’t content to just watch, though. He went out and built one himself! Even better, he’s built a guide for the rest of us, too!

His guide concerns the construction of a Class-E solid state Tesla coil. These are “underrated” in his opinion, as they’re simple, cheap, and incredibly efficient. Some say up to 95% efficient, in fact! It’s not something most Tesla coil fans are concerned with, but it’s nice to save the environment while making fun happy sparks, after all.

[Zach]’s guide doesn’t just slap down a schematic and call it good. He explains the theory behind it, and the unique features too. He uses an adjustable Schmitt trigger oscillator for the build, and he’s naturally given it an audio modulation capability because that’s a good laugh, too.

If you’ve ever wanted to convince you’re friends you’re incredibly smart and science-y, you can’t go wrong with a singing Tesla coil. This beats out Jacob’s ladder and most other plasma experiments for sheer mad scientist cred.

Have fun out there! Video after the break.

For decades now, we’ve been able to quickly and reliably interface musical instruments to computers. These tools have generally made making and recording music much easier, but they’ve also opened up a number of other out-of-the-box ideas we might not otherwise see or even think about. For example, [Joren] recently built a human interface device that lets him control a computer’s cursor using a flute instead of the traditional mouse.

Rather than using a MIDI interface, [Joren] is using an RP2040 chip to listen to the flute, process the audio, and interpret that audio before finally sending relevant commands to control the computer’s mouse pointer. The chip is capable of acting as a mouse on its own, but it did have a problem performing floating point calculations to the audio. This was solved by converting these calculations into much faster fixed point calculations instead. With a processing improvement of around five orders of magnitude, this change allows the small microcontroller to perform all of the audio processing.

[Joren] also built a Chrome browser extension that lets a flute player move a virtual cursor of sorts (not the computer’s actual cursor) from within the browser, allowing those without physical hardware to try out their flute-to-mouse skills. If you prefer your human interface device to be larger, louder, and more trombone-shaped we also have a trombone-based HID for those who play the game Trombone Champ.