Electronic Laser Harp - Sensor Edition

Hello World,

I'm officially back to show you some extraordinary gadgets like the one you are seeing right now. This project may require technical knowledge and mental brain power. This type of a instrument can't generaly be find in shops but some deep digging into the internet you could find someone who makes these sort of things or they are just selling theres because they may no longer want them.

NOTE: Some views may not be able to follow instructions properly and as time keeps ticking they may loose BIG CHUNK of their lives, if you do find yourself a person with the appropriate assets as suggested above please go ahead!

well it is a is a musical instrument made of light. A fan of beams shoots up from the floor into the night sky. The performer can create music by placing their hands in the beams. Not only does “breaking” the beam produce notes, but sliding the hand along the beam will also change the sound.

The harp does not produce any sound by itself, but creates MIDI data that can be connected to any modern synthesizer. The laser harp concept was invented by Bernard Szajnerand used extensively by Jean-Michel Jarre, and more recently Little Boots.

What is it meant by MIDI?

well what this acctually means is simply a protocol allows musical instruments to communicate with each other and with computer. So basically it like a language which could be understood by a computer, it a bit like a foreign language. Computers function to a given information, what is meant by this is that computers take in information through a series of sometimes complex or either simple code(ing).

Where is the sensoring part?

well the circuit which i will soon come to is designed so that when the laser beem is broken, using MIDI a input is given which is then converted into a form of sound (s)

the material used are quite expensive and because i own a business i cant simply hand it to you guys because of copy right.''LAME''. What you guys have to do it buy the chapters in order to finish this project. However i'm able to tell you most of the content! YAY :)

Sorry for any Problems caused.

(I fully expect Jean Michel-Jarre to raise the bar in his next concert tour, now that the cat is out of the bag regarding the traditional laser harp – not sure what he’ll come up with but I hope it’s as impressive today as the laser harp was in 1986)

The problem with the standard laser harp is that it’s not very expressive – we need more control over the sound as we break the beams. Soon after I finished the first release of the harp I was introduced to the work of Johnny Chung Lee over at the WiiMote Project site. I had no idea that the WiiMote had a hardware blob tracking camera built in to the front.

So I followed some of the examples and managed to get a WiiMote + BlueTooth + Software solution running that allowed control of MIDI parameters by sliding your hand up and down in the beam.

For this you will need:

A A WiiMote dissasembling TriWing screwdriver (warranty now void)

A BlueTooth adapter and stack (I use this one)

A .Net frameworkMy modified Wiimote software for Windows << Click to DownloadA

Copy of MidiOX and MidiYokeA Software Synth (I use this)

A Working laser harpA flask of weak lemon drink (optional)

Step One

First thing to do is open up the WiiMote and remove the black plastic filter over the front of the camera (this is a sensor made by PixArt that can track up to 4 bright “blobs” on screen). Replace the cover and attach a notch filter to the front if you have one – alternatively green transparent plastic helps. Attach the WiiMote to the harp sensor so that it has the same field of view. Step Two

Download the software . Next step is to install MidiOX and MidiYoke. We are going to create a virtual MIDI cable and merge the output of the Laser Harp with control messages from the modified WiiMote Software. Here is an excellent guide to merging two MIDI streams using MIDI-OX / MIDI-YOKE. Set this up so that MIDI Yoke-1 and the input from your laser harp are routed to Midi-Yoke-2. Then use Midi-Yoke-2 as an input to your sampler, synthesizer (or use one of your hardware outputs for an external device)

Install BlueSoleil if you have it (The built in Microsoft Blue Tooth does not seem to connect to a Wiimote correctly). Search for the WiiMote and then right-click on the icon for it and select “Connect”. If you have done it right then the device indicator will turn green. Like this: BlueSoleil and Wiimote software

Here is a guide to using BlueSoleil with the WiiMote. Run my software, if you connected the WiiMote OK then the software will run, if not you will get an error “Wiimote not in HID list”. Fill in the MIDI controller ID you want to control, and click “Run”. (On the impOSCar I’m using the frequency cutoff control which is ID 74 – although the image shows controller 77). If you have everything running and connected correctly, you can start up the harp and it should now behave like the image above

Run my software, if you connected the WiiMote OK then the software will run, if not you will get an error “Wiimote not in HID list”.

Fill in the MIDI controller ID you want to control, and click “Run”.

(On the impOSCar I’m using the frequency cutoff control which is ID 74 – although the image shows controller 77).

If you have everything running and connected correctly, you can start up the harp and it should now behave like this:

Last year I tried to find out if it were possible to connect a PixArt blob tracking camera directly to the Arduino. I knew they both spoke I2C and in theory it should be possible

Now that they have, it’s time to try to create a hardware only tracking Laser Harp. There are two sources of info out there – one from Johnny Lee himself, and the other from Kako

First off, we need to get the sensor out of the WiiMote, you can either desolder it, or just cut the board (bye bye WiiMote

Next we need to provide a 25Mhz clock signal, and 3.3V regulator to power the camera.

The Arduino does have a 3.3v line, but I think you are better off with a separate regulator.

Now the *really* tricky bit. We need to add an LTC4301L 5v/3.3v I2C buffer chip. These only come in MSOP form factor and are just like surface mount – very difficult to solder.

Adapters are available to convert the MSOP to more manageable DIP form factor

I can just about solder these things now, but it took me a couple of goes to get “the knack”. I ordered 3 of the chips – just in case.

Downloading and running Kako’s sketch should get the whole thing running,

I just finished the first pass of the C++ object library for accessing the WiiMote/Pixart sensor from an Arduino. A simple example included with the library.

I then mounted this detector along with two standard TAOS detectors in a neat metal box I found.

The second Arduino will relay the MIDI data coming from the harp body, and mix in the MIDI controller information based on the readings taken from the Pixart sensor. This is why the MIDI output port has been moved to the detector case.

I have some simple serial relay software running for the MIDI data, I just need to get the ‘merge’ function going.

well still didn't quite understood? So please visit the following link to have a much more brief detailed information + the conents which you may need to pay for:

http://www.stephenhobley.com/blog/laser-harp-2009/

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