The Simulator below can be used to see what you know about musical ratios. See if you can get all of the bars to be in tune to make the full major scale. The tuner to the side will help you out. Eventually I will add more functions, like a score keeper, turning the tuner on and off and so on, but I was ready to move on to a new project. Also the sound needs a little work. Getting it to play was easy, turning it off is something I don't think I'm doing correctly.
