Color Controller

I wanted to experiment with RGB color LED and phototransistors, given my interest in visual media and installations. As a starting point, I created a sort of “visual theremin,” which allows you to control color via your hand motions in space.

I placed four phototransistors in top, bottom, left, and right positions. Moving your hand left/right would control the blue, top/bottom would control the green, and up/down vertically (towards the board) would control the red. In order to get consistence RGB values in the range of 0-255, I needed to tweak the numbers from each of the analog input values based on observation. In the charts below, you can see the input value ranges before and after my calculations.

Because the RGB LED had a common anode, I needed to connect one of the pins to 5V, and the other three input pins provided RGB values in inverse (lower value for stronger color).

Here’s a video in action. It’s hard to see the color change because of lighting, but it’s happening!