Arduino PLC Keeps The Beat

July 6, 2024 by Bryan Cockfield 12 Comments

For most of our prototype, hobby, or one-off electronics projects it’s perfectly fine to use a development platform like an Arduino Uno or something to that effect. They’re both easy to program and easy to wire up to projects without breaking the bank. But if you step into an industrial setting where reliability is paramount even in places that are noisy, vibrating all the time, hot, or otherwise unpleasant for electronics, you’ll want to reach for a programmable logic controller (PLC) that are much more robust. There is actually a PLC from Arduino, and if you want to dip your toes into the PLC world then take a look at this drum kit based on the Arduino Opta.

With the PLC at the core of the build, it’s on to making the drumming mechanisms themselves. For that, project creator [JC Audio] is using a series of solenoids attached to camera mounts with a custom 3D printed part that allows for quick assembly and disassembly so he can get the positioning of each drum sound just right. The high hat is taken care of by the noise of an internal solenoid, with the other drums striking various real drums and other solid objects in his shops. The solenoids themselves are driven by a solid-state relay expansion module to ensure there’s enough power

While the build doesn’t sit inside a factory and run for years at a time, a musician’s stage is certainly a rough enough environment that we might reach for a PLC over a standard development board for its benefits. The code for this project is available as well at the project’s GitHub page for those looking for a more advanced timekeeper to play along with their music practice, and for more details on why you might choose a PLC for your project take a look at this Arduino vs PLC showdown from a few years ago.

Continue reading “Arduino PLC Keeps The Beat” →

Hosting Your Own PixMob Party Made Easy

June 28, 2024 by Tom Nardi 10 Comments

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.

Rock Out Without Getting Knocked Out

June 27, 2024 by Alexander Rowsell 20 Comments

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!

A Simple Laser Harp MIDI Instrument

June 19, 2024 by Dave Rowntree 5 Comments

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.

Educational Breadboard Synth Module

June 15, 2024 by Alexander Rowsell 11 Comments

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!

Continue reading “Educational Breadboard Synth Module” →

Marimbatron: A Digital Marimba Prototyping Project

June 13, 2024 by Dave Rowntree 6 Comments

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.

The final polyurethane/PET/Flex PCB stack-up for the sensor pad

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.

Continue reading “Marimbatron: A Digital Marimba Prototyping Project” →

ESP32 Powered Crunch-E Makes Beats On The Go

June 11, 2024 by Tom Nardi 6 Comments

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.

Continue reading “ESP32 Powered Crunch-E Makes Beats On The Go” →