Listen to the colours

This instrument uses RGB LEDs to illuminate the tested surface and plays tones depending on phototransistor response. 

When the key is pressed, it plays the tone (about 200 ms), with lower pitch if the red component is darker, and higher pitch if it is lighter. The same is for green and blue, so the whole sequence is about 600 ms. After that, if the momentary key is still ON, MCU goes to sleep mode, to save battery. The key simply switches power supply ON and OFF. 

This instrument helps blind persons or daltonists to get more information about their surrounding. After some time they will not listen the tone pitches, but the "melody" of the colour. 

The lower part of the inside surface of the enclosure must be black, and the photo transistor light shielded (with the black heat shrinkable tube or so), to ignore direct light from LEDs and to pick only the reflected light from the tested surface.


Here's the schematics...:

...and YouTube demo: