Trashed Sound System Lives To Rock Another Day

May 22, 2025 by Bryan Cockfield 6 Comments

Plenty of consumer goods, from passenger vehicles to toys to electronics, get tossed out prematurely for all kinds of reasons. Repairable damage, market trends, planned obsolescence, and bad design can all lead to an early sunset on something that might still have some useful life in it. This was certainly the case for a sound system that [Bill] found — despite a set of good speakers, the poor design of the hardware combined with some damage was enough for the owner to toss it. But [Bill] took up the challenge to get it back in working order again.

The main problem with this unit is that of design. It relies on a remote control to turn it on and operate everything, and if that breaks or is lost, the entire unit won’t even power on. Tracing the remote back to the control board reveals a 15-pin connector, and some other audio sleuths online have a few ways of using this port to control the system without the remote.

[Bill] found a few mistakes that needed to be corrected, and was eventually able to get an ESP8266 (and eventually an ESP32) to control the unit thanks largely to the fact that it communicates using a slightly modified I2C protocol.

There were a few pieces of physical damage to correct, too. First, the AC power cable had been cut off which was simple enough to replace, but [Bill] also found that a power connector inside the unit was loose as well. With that taken care of he has a perfectly functional and remarkably inexpensive sound system ready for movies or music. There are some other options available for getting a set of speakers blasting tunes again as well, like building the amplifier for them from scratch from the get-go.

Stylus Synth Should Have Used A 555– And Did!

May 20, 2025 by Tyler August 8 Comments

For all that “should have used a 555” is a bit of a meme around here, there’s some truth to it. The humble 555 is a wonderful tool in the right hands. That’s why it’s wonderful to see this all-analog stylus synth project by EE student [DarcyJ] bringing the 555 out for the new generation.

The project is heavily inspired by the vintage stylophone, but has some neat tweaks. A capacitor bank means multiple octaves are available, and using a ladder of trim pots instead of fixed resistors makes every note tunable. [Darcy] of course included the vibrato function of the original, but no, he did not use a 555 for that, too. He used an RC oscillator. He put a trim pot on that, too, to control the depth of vibrato, which we don’t recall seeing on the original stylophone.

The writeup is very high quality and could be recommended to anyone just getting started in analog (or analogue) electronics– not only does [Darcy] explain his design process, he also shows his pratfalls and mistakes, like in the various revisions he went through before discovering the push-pull amplifier that ultimately powers the speaker.

Since each circuit is separately laid out and indicated on the PCB [Darcy] designed in KiCad for this project. Between that and everything being thru-hole, it seems like [Darcy] has the makings of a lovely training kit. If you’re interested in rolling your own, the files are on GitHub under a CERN-OHL-S v2 license, and don’t forget to check out the demo video embedded below to hear it in action.

Of course, making music on the 555 is hardly a new hack. We’ve seen everything from accordions to paper-tape player pianos to squonkboxes over the years. Got another use for the 555? Let us know about it, in the inevitable shill for our tip line you all knew was coming. Continue reading “Stylus Synth Should Have Used A 555– And Did!” →

Zen Flute Is A Teensy Powered Mouth Theremin

May 17, 2025 by Dave Rowntree 13 Comments

An intriguing mouth-played instrument emerged—and won—at the 2023 Guthman Musical Instrument Contest hosted by Georgia Tech. [Keith Baxter] took notice and reproduced the idea for others to explore. The result is the Zen Flute Mouth Theremin, a hybrid of acoustics, electronics, and expressive performance.

At its core lies a forced Helmholtz resonator, a feedback system built with a simple microphone and speaker setup. The resonator itself? The user’s mouth. The resulting pitch, shaped by subtle jaw and tongue movements, is detected and used to drive a MIDI controller feeding an external synthesizer.

Like a trombone or classic electromagnetic theremin, the Zen Flute doesn’t rely on discrete notes. Instead, the pitch is bent manually to the desired frequency. That’s great for expression, but traditional MIDI quantisation can map those “in-between” notes to unexpected semitones. The solution? MIDI Polyphonic Expression (MPE). This newer MIDI extension allows smooth pitch transitions and nuanced control, giving the Zen Flute its expressive character without the hiccups.

Physically, it’s an elegant build. A flat speaker and microphone sit side-by-side at the mouth end, acoustically isolated with a custom silicone insert. This assembly connects to a length of clear PVC pipe, flared slightly to resemble a wind instrument. Inside, a custom PCB (schematic here) hosts a mic preamp, an audio power amp, and a Teensy 4.1. The Teensy handles everything: sampling the mic input, generating a 90-degree phase shift, and feeding it back to the speaker to maintain resonance. It also detects the resonant frequency and translates it to MPE over USB. A push-button triggers note onset, while a joystick adjusts timbre and selects modes. Different instrument profiles can be pre-programmed and toggled with a joystick click, each mapped to separate MIDI channels.

Mouth-controlled instruments are a fascinating corner of experimental interfaces. They remind us of this Hackaday Prize entry from 2018, this wind-MIDI hybrid controller, and, of course, a classic final project from the Cornell ECE4760 course, a four-voice theremin controlled by IR sensors.

Continue reading “Zen Flute Is A Teensy Powered Mouth Theremin” →

Boxie – A Gameboy-Esque Audio Player

May 11, 2025 by Matt Varian 8 Comments

This little audiobook player is a stellar example of the learning process behind a multifaceted project blending mechanical, electrical, and software design. [Mario] designed this audiobook player, dubbed Boxie, for his 3-year-old son to replace the often-used but flawed Toniebox.

The inspiration for Boxie was the Toniebox, a kid-friendly audiobook player. While functional, the Toniebox had drawbacks: it required internet connectivity, limited media selection, and had unreliable controls. Enter Boxie, a custom-built, standalone audiobook player free from web services, designed to address these issues with superior audio quality and toddler-friendly controls.

Boxie’s media is stored on microSD cards inserted into a slot on the device. To make this manageable for a toddler, he designed a PCB with a standard microSD card interface, ensuring easy swapping of audiobooks. The enclosure, crafted via 3D printing, is durable and compact, tailored for small hands.

Continue reading “Boxie – A Gameboy-Esque Audio Player” →

A Yamaha smart speaker, now with external DAC.

Smart Speaker Gets Brain Surgery, Line-Out

May 2, 2025 by Tyler August 4 Comments

Sometimes you find a commercial product that is almost, but not exactly perfect for your needs. Your choices become: hack together a DIY replacement, or hack the commercial product to do what you need. [Daniel] chose door number two when he realized his Yamaha MusicCast smart speaker was perfect for his particular use case, except for its tragic lack of line out. A little surgery and a Digital-to-Analog Converter (DAC) breakout board solved that problem.

You can’t hear it in this image, but the headphones work.

[Daniel] first went diving into the datasheet of the Yamaha amplifier chip inside of the speaker, before realizing it did too much DSP for his taste. He did learn that the chip was getting i2s signals from the speaker’s wifi module. That’s a lucky break, since i2s is an open, well-known protocol. [Daniel] had an Adafruit DAC; he only needed to get the i2s signals from the smart speaker’s board to his breakout. That proved to be an adventure, but we’ll let [Daniel] tell the tale on his blog.

After a quick bit of OpenSCAD and 3D printing, the DAC was firmly mounted in its new home. Now [Daniel] has the exact audio-streaming-solution he wanted: Yamaha’s MusicCast, with line out to his own hi-fi.

[Daniel] and hackaday go way back: we featured his robot lawnmower in 2013. It’s great to see he’s still hacking. If you’d rather see what’s behind door number one, this roll-your-own smart speaker may whet your appetite.

Terminal DAW Does It In Style

April 30, 2025 by Fenix Guthrie 30 Comments

As any Linux chat room or forum will tell you, the most powerful tool to any Linux user is a terminal emulator. Just about every program under the sun has a command line alternative, be it CAD, note taking, or web browsing. Likewise, the digital audio workstation (DAW) is the single most important tool to anyone making music. Therefore, [unspeaker] decided the two should, at last, be combined with a terminal based DAW called Tek.

Tek functions similarly to other DAWs, albeit with keyboard only input. For anyone used to working in Vim or Emacs (we ask you keep the inevitable text editor comment war civil), Tek will be very intuitive. Currently, the feature set is fairly spartan, but plans exist to add keybinds for save/load, help, and more. The program features several modes including a multi-track sequencer/sampler called the “arranger.” Each track in the arranger is color coded with a gradient of colors generated randomly at start for a fresh look every time.

Modern audio workflows often span across numerous programs, and Tek was built with this in mind. It can take MIDI input and output from the JACK Audio Connection Kit, and plans also exist to create a plugin server so Tek could be used with other DAWs like Ardor or Zrythm. Moreover, being a terminal program opens possibilities for complicated shell scripting and other such Linux-fu.

Maybe a terminal DAW is not your thing, so make sure to check out this physical one instead!

Pi Pico Throws Us For A (MIDI) Loop

April 28, 2025 by Tyler August 3 Comments

Modern micro-controllers are absolute marvels, but it isn’t too many projects use one and nothing else. For an example of such simplicity, take a look at [oyama]’s Pi Pico MIDI looper.

It uses the PicoW to interface with a synth via MIDI-BLE, which can be anything from pro equipment to an app on your smartphone. The single control button is already provided by the Pico W– the bootsel button is wearing a lot of hats here, allowing one to select betwixt 4 tracks (all different drums), set the tempo, and input notes on the selected track.

The action is simple: pound out the rhythm for each track, and it will repeat forever, or at least until you press the single button again to change it. There’s also a nice serial interface so you can see what’s going on via UART or USB. For what it does, it is amazingly simple: the BOM is one item, the Pi Pico W. To see it in action, check out the demo video below.

Given the ADC chops on the Pico, it would probably be easy to extend this build with a speaker to make a tiny stand-alone, one-button synth. Or you could add more buttons buttons, but then it’s no longer the beautifully simple single-line BOM project that [oyama] showed us.

Of course, everything is open-source on GitHub, under the BSD license, and forking is encouraged, so [oyama] would doubtless be more than happy to see you go nuts hacking and extending this tiny MIDI looper.

We’ve actually seen the MIDI-BLE standard used before, like this hack adding it to a Eurorack. If you like synths, you may be interested to see what it takes to design one from scratch, sans microcontroller. Continue reading “Pi Pico Throws Us For A (MIDI) Loop” →