We’ve successfully gotten the first stage of our guitar hero bot working. In the video below, you can see a prototype of our photodiode circuit correctly viewing the notes on the screen, and blinking the LED appropriately. For now, We are only detecting the green notes, but more are soon to come. If you look closely at the oscilloscope, you can see the nearly perfect digital square waves. Before implementing the circuit shown in the diagram, the photodiode signal was very noisy and weak.