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________________________________________________________________________

This is how it looks and this is how it sounds

Yeah, uhhm, I wanted a little guitarish thing to play powerchords on.
You know to bring to festivals and impress girls and all that.
Something that is easily connected to my little amplifier, that I
made from an old mc-player, follow this link to check it out.

Anyways, I built this using an ukulele as size-model.
Ukulele strings, if you buy a 4 pack of ukulelestrings I used the fattest
next fattest and the thinnest.
I’ve tuned them to C, E, C (one octave higher) to play them powerchords.
I did not frett it, just drew with a pen on, if you want to fret it best
use a chromatic tuner for to find the sweetspots on the neck.
The tuning pegs are from a cheapo kids acoustic guitar, cheap but working.
A large pice of metal (actually a bbq pin) is bent to hold the strings down.
A pice of square metal is used as to lay the strings on.
Same pice of bbq stick is used to rest the strings at on the end of the
string instrument.
The pickups are piezo discs connected in serial to increase the volume.
And the jack is a standard guitarjack.

Top View

Back.

Dont do mistakes, then you have to glue stuf together.

Side of head.

Back of head.

The jack from behind.
Forgot to take a closeup photo of the unpainted front, sorry.

A bunch of tips:
* Pizeo tutorial at Erinys superb how-to
* Get the tuning pegs first, and measure everything, otherwise you will end up with
a few more holes then expected (as I did)
* You can use metallic strings, but that its not needed with piezos.
* Try different placements on the picups before attatching them (you can alter the
sound pruduced radically, I went four loud volume though)
* Have fun.

And Finally some pictures of me rocking out on it.

What why?

A while ago I found an interesting post on the arduino forums about
a guy who made a 8×8 LED panel for his friend to use to visualise when
playing music. So when I was browsing my local thrift-store
I found an old slide viewer (for you kids, it’s an old pre digital way
to take photo’s).

-Hell yeah I thought (but in Swedish) this would look sweet if I mounted
a bunch of LED’s in it. So i bought it for 15 SEK. (1.51 EUR or 1.9 USD)

Hardware.

I have already made almost all of the arduino-code I needed on my
moanonme. Also the 8×8 LED matrix is no mystery to me. If you want to
recreate it it’s dead easy. First you read the shiftout tutorial on
arduino.cc and make one of those a bit more permanent. After that you
make 7 more rows with led’s and connect each row’s gnd to a different
pin on the Arduino. Then with a little bit of code magic you write to
the shift register which led’s that are on on a specific row. that row
being set to “read” in the software forcing that row to be the only one
that is lit. By doing this superfast you’re eye wont notice the difference.

This might sound easy, and it is, unless you do it on a small scale. The
Lens on the slide viewer was only 3*4cm so I needed LED’s that would fit.
I found some green that fitted perfectly. I tried to glue them toghether
first but in the end that was all a big heap of fail. easiest was to use
a perfboard and mount them on that. I used an iDuino board since these are
smaller and thus easier to mount inside the pretty cramped battery
compartment inside the box.

Decimilia used for prototyping

Backside of LED matrix

The 595 chip shiftout for the led’s

Software

There where a few features I wanted of the finished build. I wanted to
easily create sprites/images. And I wanted to be able to controll the
displaying of the images from within Ableton Live. Prefferably as a
MIDI device so I would not have to code yet another VST.

So yep a very tiny little Arduino program which you can get here

So I made a little processing sketch that let’s you draw on your computer
screen and both show it there and on the device. This was as really easy.
Press 2 to paint, 3 to erase and 1 to print the image in data format so
I can copy-paste it to a server program. I choose to print the data in a
human readable/modifiable code so I could change it without the program if
I wanted to.

Here it is if you want to play with it: opalpainter.pde (you’ll need
processing)

So to the serverside. Easypeasy aswell as always with processing, chose
another type of visualisation though. It all worked well until I tried
to get any of the MIDI processing solutions to work. fail fail fail.
It works though, and here it is for your playing fun: opalserver.pde
1 and 2 to flip between your images

So in the end I reused stuff from the moanonme project. os x serialport and
MIDI in from a totally own port. Most of this code is not written by me
although I’ve seen that os x serialport stuff on more then five different
places on the internet so I’m not really sure who’s the original author.
Anyways, this program listens to midi-in and tells the arduino to display
graphics I hooked up to the current MIDI note. get it here

The video

What would a build be without a video? nothing, since nobody reads these text’s
of mine that’s what!

Total Cost:

Arduino iDuino 17.82 USD
Diabildsvisare 1.91 USD
LED’s 4.57 USD
some wire and solder 1 USD
——————————-
Total 25.3

just below 200 SEK, NICE!