Effects pedals: for some an object of overwhelming addiction, but for many, an opportunity to hack. Anyone who plays guitar (or buys presents for someone who does) knows of the infinite choice of pedals available. There are so many pedals because nailing the tone you hear in your head is an addictive quest, an itch that must be scratched. Rising to meet this challenge are a generation of programmable pedals that can tweak effects in clever ways.
With this in mind, [ElectroSmash] are back at it with another open source offering: the pedalSHIELD MEGA. Aimed at musicians and hackers who want to learn more about audio, DSP and programming, this is an open-hardware/open-software shield for the Arduino MEGA which transforms it into an effects pedal.
The hardware consists of an analog input stage which amplifies and filters the incoming signal before passing it to the Arduino, as well as an output stage which does the DAC-ing from the Arduino’s PWM outputs, and some more filtering/amplifying. Two 8-bit PWM outputs are used simultaneously to make pseudo 16-bit resolution — a technique you can read more about in their handy forum guide.
The list of effects currently implemented covers all the basics you’d expect, and provides a good starting point for writing custom effects. Perhaps a library for some of the commonly used config/operations would be useful? Naturally, there are some computational constraints when using an Arduino for DSP, though it’s up to you whether this is a frustrating fact, or an opportunity to write some nicely optimised code.
[ElectroSmash] don’t just do pedals either: here’s their open source guitar amp.
Continue reading “Stomping On Microcontrollers: Arduino Mega Guitar Effects Pedal”
Ever since Jimi Hendrix brought guitar distortion to the forefront of rock and roll, pedals to control the distortion have been a standard piece of equipment for almost every guitarist. Now, there are individual analog pedals for each effect or even digital pedals that have banks of effects programmed in. Distortion is just one of many effects, and if you’ve built your own set of pedals for each of these, you might end up with something like [Brian]: a modular guitar pedal rack.
Taking inspiration from modular synthesizers, [Brian] built a rack out of wood to house the pedal modules. The rack uses 16U rack rails as a standard, with 3U Eurorack brackets. It looks like there’s space for 16 custom-built effects pedals to fit into the rack, and [Brian] can switch them out at will with a foot switch. Everything is tied together with MIDI and is programmed in Helix. The end result looks very polished, and helped [Brian] eliminate his rat’s nest of cables that was lying around before he built his effects rack.
MIDI is an extremely useful protocol for musicians and, despite being around since the ’80s, doesn’t show any signs of slowing down. If you want to get into it yourself, there are all kinds of ways that you can explore the studio space, even if you play an instrument that doesn’t typically use MIDI.
Sometimes we get lucky and find a part we need for a project in our parts drawer. [Scissorfeind] got even luckier and found a part for his project lying around in the street. It was a Crybaby Wah pedal, a classic effects pedal typically used for a guitar. Since it was somewhat damaged, [Scissorfeind] got to work creating a control voltage (CV) and volume circuit for his Korg synthesizer.
For those who aren’t synthesizer aficionados, CV is a method of controlling the pitch of a tone. A higher voltage creates a higher tone and vice-versa. The wah pedal has a rocker on it that allows one’s foot to control the effect, but this particular one has been modified for CV instead of the wah-wah sound these pedals normally make. [Scissorfeind] built in a switch that will allow it to control volume as well, which makes this pedal quite unique in the effects world.
[Scissorfeind] built the custom circuit out of other parts he had lying around (presumably not in the street) and put the entire thing together on perfboard, then fit it all back together in the pedal. Now he has a great control voltage pedal for the vintage Korg synthesizer he recently restored! [Scissorfeind] knows his way around a synth, but if you’re looking to get started on a synthesizer project we have a great tutorial for you!
When the apocalypse hits and your power goes out, how are you going to keep yourself entertained? If you are lucky enough to be friends with [stopsendingmejunk], you can just hop on his pedal powered cinema and watch whatever movies you have stored on digital media.
This unit is built around an ordinary bicycle. A friction drive is used to generate the electricity via pedal power. In order to accomplish this, a custom steel stand was fabricated together in order to lift the rear wheel off the ground. A 24V 200W motor is used as the generator. [stopsendingmejunk] manufactured a custom spindle for the motor shaft. The spindle is made from a skateboard wheel. The motor is mounted in such a way that it can be lowered to rub the skateboard wheel against the bicycle wheel. This way when the rear bicycle wheel spins, it also rotates the motor. The motor can be lifted out of the way when cruising around if desired.
The power generated from the motor first runs through a regulator. This takes the variable voltage from the generator and smooths it out to a nice even power signal. This regulated power then charges two Goal Zero Sherpa 100 lithium batteries. The batteries allow for a buffer to allow the movie to continue playing while changing riders. The batteries then power the Optomo 750 projector as well as a set of speakers.
[Lee O’Donnell] is showing off his version of a MIDI organ pedal hack. We’ve been seeing a few of these lately. The organ pedals are a great stating point as they’re easy to patch into electronically, and are designed to take a beating from your feet and come out the other side no worse for wear. The build goes beyond one of our favorite MIDI pedal conversions in both features and finish.
An Arduino Nano pulls this project together. It scans the pedals constantly and converts the key presses into MIDI signals. But the design includes this fabulous looking front-end which [Lee] first prototyped in cardboard before cutting and bending his own Aluminum tread plate. A two-row character display provides a menu system, but the buttons themselves act as feedback based on the behavior of the light inside each of them. One example of this is shown early in the demo video after the break. The blue button toggles between polyphonic and monophonic mode with the light fading in and out for the latter.
Continue reading “MIDI pedal project looks as good as it sounds”
Drumming hackers take note, if you’ve got an extra bass drum pedal it’s cheap and simple to use it as a MIDI controller. This rig was thrown together to supplement a DIG DRUM electric drum set. That piece of equipment has a pedal add-on that didn’t come with it. Turns out all it does is feed a resistance value to the set.
To get this up and running a frame was built from a metal base and acrylic side piece. The acrylic hosts a trimmable potentiometer which connects to an 1/4″ stereo jack right beside it. This facilitates connecting the pedal to the drum set using an audio patch cable. Interface with the pedal is accomplished with a few bits from the hardware store. The axle of the pedal sticks out one side, and is clamped between two washers. The other side of the washer grip the timpot causing it to move when the pedal does.
This hardware is a snap to use with your own MIDI device. We’d suggest giving the HIDUINO package a try.
Your hands do a lot of work between the keyboard and the mouse, why the heck are you letting your feet be so lazy? [Dossier van D.] is putting an end to the podiatric sloth. He built this set of three foot pedals which have gone through two versions of functionality.
The buttons themselves are made from a base plate of plywood with a smaller piece on top for each ‘key’. The two parts are separated with some foam carpet pad, with a tactile push button in between to register a click. The only thing we’d change about this is adding a couple of wooden spacers next to the switch so that accidentally sanding on a button doesn’t break that electronic component.
Originally each button was soldered to a gaming controller. This worked just fine using button mapping, but recently [Dossier] made the switch to using an Arduino Leonardo. This is a perfect choice. Unlike input devices made with older Arduino versions the Leonardo board can natively register as a keyboard, making it a snap to programmatically map any key to the switches.
If you like this project you should check out [Dossier’s] foot mouse as well.