After experimenting with LDRs, I wanted to take this idea further. I had since decided that throwing things at an instrument wouldn’t provide the degree of control that I wanted, and therefore, decided that light or infrared would provide a similar user experience (in the sense that the user must stand away from the instrument to control it.)


Basic sketch of Light Instrument

Rather than diving right in to build this instrument, I deemed it necessary to first build a very simplified prototype, as I had not used more than one LDR to build a viable instrument. I decided to use a button to toggle between three parameters: Pitch; Modulation and; Amplitude.

To begin, I connected five LDRs to my Arduino and attached them to analogue inputs 0 through 4. I also connected a button to digital input 2. An image of the setup and the Arduino code can be seen below:


Arduino setup


I wanted to use Max MSP to produce the sound of this instrument. What the setup of the Arduino does is produces two pieces of information for Max to use. The first piece of information describes one of three states that the button is in, whilst the second piece of information describes which LDR has been triggered. In order for an LDR to be triggered, it must read a value of of over 200.

When Max receives this information, it will use the LDR information to change one of the three parameters based on the state of the button. Below is a screenshot of the Max patching screen used with the instrument:


Screenshot of Max patch screen

I included some visual representation of the modulation (in this instance called tremolo), pitch and amplitude through the use of sliders and a dial. As the light moves up and down the row of LDRs these values will increase and decrease, as can be seen in the video below:

Video of Light Instrument


Layout of mobile phone GUI

Whilst this instrument is crude, it does show that LDRs can be used in many ways to control an instrument. I had considered using infrared as a way to control it, but since most infrared devices beam codes to a reader, I decided that light would still provide the best visual representation. I have therefore deemed that the instrument I build will need to be used as more of an installation than a portable instrument. To take this idea further, I will use a large board to create a more viable instrument with a greater deal of control. I also plan to use Bluetooth to control the entire instrument (see image above). This way, the instrument can be played using just a mobile phone, as most phones which run apps have torches. This also allows it to be played by more than one person.


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