Instructables

OpenChord.org V0 - Build a Real Guitar Guitar Hero/Rock Band Controller

We all love Guitar Hero and Rock Band. We also know that we'll never learn how to actually play guitar playing these games. But what if we could at least build a Guitar Hero controller that let us use a real guitar? That's what we here at OpenChord.org are trying to do.

This instructable will show you how to take a regular electric guitar and turn it into the OpenChord V0, a Guitar Hero / Rock Band controller that you play by actually playing notes on the guitar. Instead of pressing buttons, you'll be pressing strings, sliding up and down the fretboard to connect notes together.  However, it still relies on the internals of a Guitar Hero controller to generate the proper signals to the console, and it uses the strum bar from the controller as well.

 This project has been superseded by the OpenChord V1, which actually uses the real strings and generates real controller signals.

For a little more information about the project as a whole, visit OpenChord.org.


 
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Step 1: Theory of Operation

Picture of Theory of Operation
The basic idea of this guitar is to use the strings and frets of the guitar as a circuit. When you play a note on the guitar, you press the string between two frets. If we connect the string to a voltage source and the frets to a ground, each time a note is held down, it creates a circuit. By connecting each fret to a microcontroller, we can then measure which frets the string is touching. Finally, we can do this process for each string on the guitar, measuring (almost) where every finger is.

Why almost? Once more than one string is involved, some ambiguous situations arise. For instance, electrically, holding two strings down at the second fret is no different from holding one finger down on the first fret and another on the second fret, because the fret connects everything together. Fortunately, we'll deal with this in software...
wrecklesst1 year ago
I made mine wireless and invisible. sure get funny looks while I am playing though..

alan.chatham (author)  wrecklesst1 year ago
Awesome! I'd love to see pictures if you've got some!
dynno974 years ago
Poor guitar... Cool project... but why did you have to kill that little guitar...
alan.chatham (author)  dynno974 years ago
This project has kinda moved on - the newer version is here: http://www.instructables.com/id/Play-Guitar-Hero-with-a-Real-Guitar/ In the new version, you're actually using a wired-up pick instead of the strum bar, and so you don't have to add anything else onto the faceplate of the guitar - you can install it internally to the guitar and the guitar will still play just like a regular electric guitar!
Forgive me if this is a stupid question; Can a midi guitar be used for this? I'd look into it myself but whenever I read the word arduino my head starts spinning and I have to curl up into the fetal position. Regarding a metal pick; I made one by placing a nickle on a railroad track and then shaping it with a file. Perhaps a double pick, one side positive the other negative could be used? (once again the arduino thing happened before I was able to completely understand the circuitry so this answer may not be applicable). I know I'm a bit late but just had to input my five cents. Impressive project, to say the least.
alan.chatham (author)  VagsmaCutter4 years ago
 So I've moved away from the Arduino - I'm now using my own PCB and a regular ATMega328 without all the extra Arduino nonsense.  There are instructions for that on the website, as well as an instructable here showing how to make a version of the guitar without the Arduino.

In fact, in the latest board revision, I've freed up the serial pins on the microcontroller, so hopefully I'll be using it to implement MIDI out.  However, it could also be used to take in MIDI data and create controller signals as well....
Right on. I was thinking along the lines of using a guitar that already output midi. But, it's not like I've got one laying around for parts and I don't know if one would even work for this application. Not to mention buying parts is against my religion so making the thing would probably be what I would do. Of course I'm not insane/ sane enough to embark on such a journey and follow it to fruition without heavy collateral damage/ casualties along the way (not saying you're insane, on the contrary, I admire your sackitude for even attempting doing what you're doing AND what you have done.) I will visit the site as soon as I can wake up enough grey matter to do it justice. Honestly, I'm pushing overload as it is. Good stuff man.
8bit4 years ago
Wow, great idea. Who would have thought it could be so simple? 
Option 1(strum bar is a switch): If you didn't want to use the strum bar, id suggest using your electrified strings in concert with a metal pic (if you can find one)(no pun intended!) that is wired to one side of the strum switch and get the strings to attach to the other side of the switch Option 2(strum bar is an odd potentiometer): get one of those digital potentiometer chips, like for the audio controllers and such(maxim has some) and do the same thing with option 1, except run the connections to the chip, then to wherever it was going in the first place. I apologize if that makes little sense, but I'm sleep deprived right now and could be clearer headed later
alan.chatham (author)  The Ideanator5 years ago
Thanks for the advice! I've thought about using a metal pick; made one out of tinfoil and stuff, but I spent a bunch of time focusing on how to get the code to work for the strings, then interfacing with the GH controller, so I kinda let that slip by the wayside... I should look into that. Thanks! Not sure about what you mean with the potentiometer, though... I'm intrigued! Let me know more, or e-mail develop@openchord.org. Thanks!
matthewruth5 years ago
Sweet work here guys I'm contemplating where i can get my hands on a cheap guitar and a guitar hero controller. I'd be aiming for a xbox 360 controller - so making it wireless, as i have an xbox 360. It will go on my To-Do list......
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