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Making a guitar (some bits) more fun

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This idea has been spinning around my head for a long time, and I finally had the time, the knowledge and the motivation for doing it. Much has been said about how wonderful is the Wii, and about the possibilities of the Wiimote as a controller for many exciting applications. We’ve been using a Wiimote in my band KillDemonios (and I want to do it with La Fábrica as well) as a controller for synthesizers, and I wanted to do something with my guitar, something that went a little bit beyond taping the controller to the body of the instrument. Read on to see is what I did (video at the end).

I never use the tone knob of my Schecter 006 Deluxe, so I wanted to use it for something cool. What about sending MIDI data to a guitar processor or any other software? How to do the trick?

I don’t want to have more cables between me and my guitar processing stuff. I don’t even like the standard cable, but I have to live with that (at least until I can afford a decent wireless system). So the Wiimote, with its bluetooth connection capabilities seemed like an excelent option. It’s range is supposed to be around 10 meters, which is not too much, but I still don’t perform in Wembley-like arenas, so I think it’s ok for now. However, besides the accelerometers, the Wiimote lacks analog controls. That’s what a (relatively) inexpensive Nunchuk is for. So, Guitar+Nunchuk=fun (I wanted to show a detailed tutorial, but unfortunately I didn’t take photos from the beggining, so the only thing I can show now is photos of the finished project and a small description of the process).

The first thing I did was opening my guitar, unscrewing the tone pot and unsoldering it. It’s a good idea to understand the (simple) circuit of the guitar, so you can replace the pot with a resistance without altering the tone. In my case, I found the schematics here. The schematics are usually available in the webpages of the guitar manufacturers. There’s alse plenty of web sites which deal with the subject, also. The pot was in series with a capacitor, which I also unsoldered. I recreated the circuit replacing the pot (which was 500KOhms) with a resistance, and soldering it in series with the capacitor and then to ground. I compared the original guitar sound with the sound obtained using different resistance combinations. Just one 470KOhms resistance sounded good for me:

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470KOhm resistance in series with the capacitor

Then I soldered a cable and a small connector to the pins of the potentiometer:

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It used to be a tone pot...

That was all about the guitar circuitry. Pretty simple, huh? Then the Nunchuk part. I bought a black Nunchuk, since I will use the cable and prefer it to be black.  I needed to open the Nunchuk. It, however, uses two screws which are very difficult to unscrew, because they have a triangular shape, much like a Mercedes-Benz logo, so I decided to destroy the case in order to open it. I did it very gory-wise and I wouldn’t recommend doing it like that. It would be better to do it in a more civilized way, like these guys did: Wii Nunchuk Dissection and Comparison. I strongly suggest reading that link in order to become familiar with the device before opening it.

Once opened, you will find a small circuit board with some stuff attached: the joystick (very similar to this), an even smaller board with the contacts of the two buttons and the cable which goes to the Wiimote. I got rid of the joystick and unsoldered the two potentiometers that it controls. These pieces came out and I threw them away (after taking a photo of them):

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Clockwise, from top-left corner: The joystick handle, the joystick cage wich has the spring-loaded mechanism, some random Lego piece (just kidding, it's really the membrane of the buttons) and one of the two potentiometers

Then I soldered two empty female headers (like these) in place of the potentiometers:

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Modified guts of a Nunchuk

Now I have a sensor interface where I can accommodate two analog sensors (and also two digital sensors: the buttons, which are still unused and can be seen taped in the photo). As a plus, I have a 3-axis accelerometer already soldered, and all that for just €20. Great!

Right now the next step is pretty obvious: just connect the pot to one of the sensor inputs, connect the cable to the Wiimote and voilà!

I’ll mention the software part in a minute, first, I certainly need to have a way to accommodate the circuit board and to take the cable out of the guitar. I only have one guitar (and I love it), so I didn’t want to do anything irreversible to it. So I made a “custom” back cover out of a DVD box (it was from the movie Seven, in case you’re curious. Excellent movie, by the way). I cut the straight lines with a cutter, and the round corners with the scissors of a swiss army knife:

Custom back cover. Courtesy of David Fincher.
Custom back cover. Courtesy of David Fincher.

I drilled a hole to let the Nunchuk cable out and another two small holes, for inserting a pair of small plastic bolts to hold the circuit board in place:

Custom back cover from a back cover
Custom back cover from a back cover
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Custom... you get the idea
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Whatever

I tied the Wiimote to the strap of the guitar and connected the Nunchuk to it. It looks a little bit weird, but you can use those additional controls too (11 buttons and another 3-axis accelerometer… good!). And this is finally how it looks:

Back
Back

I’m planning to buy a black Wiimote , which I think would look better on the black strap (hmm… another €40… maybe it would be cheaper to buy a white strap!).

Coolest guitar in town
Coolest guitar in town

For interfacing the Wiimote with software (and eventually with hardware), there are some options around. If you use a Mac, I strongly recommend Osculator. I allows you to map all Wii controls to practically anything: MIDI controls or notes, OSC routings, HID controls and a long et cetera. It’s really worth its price. There’s also Darwiinmote, which converts only to OSC (I think). For PC, you have GlovePIE. If you want to do some complex controller mappings, you definitely should use Pure Data.

I will post some more info on mapping and programming soon, and also a video example of what can be done soon as the video is already up! See it:

That’s it.

Thanks for reading. Thanks to Ina for the correction of the title.

JP

9 thoughts on “Making a guitar (some bits) more fun

  1. No es que entienda del todo el mecanismo, pero se que ahora es una guitarra nada común, como te gustan las cosas a ti. Diferentes y mejores. Te amo. Felicitaciones

  2. Sobrino JuanPa:
    La guitarra tiene ahora más cosas que un vó…..
    Te felicito por tu berraquera y el excelente inglés.
    Un muy fuerte abrazo,
    Poncho

  3. Juanpa!

    Te recuerdo que hay que mapear el eje horizontal del acelerómetro, así podrás deleitar a tod@s tus admirador@s con unos movimientos rítmicos de cadera al mejor estilo de Los Demonios del Caribe. Espero cuanto antes un video de eso!!!

    Pon.

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