You have definitely have heard of a piano or a digital piano before, but have you ever heard of a flexible Mechanical NXT keyboard piano? Pianos are one of the most interesting and popular instruments for billions of people to play and learn, but often cost more than what everyone can afford. My piano only costs around 200 dollars whereas the digital piano costs minimum around 400 dollars and averagely around 1000 dollars, so everyone can afford it and create their own music. They can also learn about programing, circuit design, and mechanical assemblies in a fun way.
There are five circuit boards on the model and each has five sound buttons. Digital pianos create sound when the key that is pressed down by our finger hits the sound buttons inside of the piano. However, instead of pressing down the buttons, I place my circuit board on the wall of my piano so that you need to push the key toward the buttons in order to create sounds. I created a special “seesaw” with two keys on top of another with different angles. If you press down one key, the end will bump up the other key. I put a bumper with special angle on the end of the second key so that when it is bumped up by the lower key, it would push the key button to make sounds. Every digital piano uses springs to control the motion of keyboard by pressuring when it goes up and release it to gain force. I used elastic energy instead. The middle of two keys are connected using elastic bands so that after I press down the lower key and bump up the upper key, the elastic band will tightened and release automatically after my finger leaves the key board.
Although I didn’t really calculate the actual time of building each part of the piano, I can still estimate the time and the whole progress of making the MechNXT keyboard. I spent almost a week thinking about different interesting projects that can bond both music and mechanics together. After I decided the topic of my project, I made three different types of keyboards, each with a different solution to make sounds. After I finally decided and built one key by using my favorite and interesting mechanical structure, I spent around 30 minutes building an independent keyboard with 5 semi-notes. I spent another 30 minutes thinking about how to connect two or more independent keyboards together by making special and fixed connection.
It took me another week thinking about an innovative way to let my piano makes sounds. I first thought about using different length and depth of woods, however, I decided to use some more high tech solutions. I got my circuit board idea when I was playing around with my Electronic Snap Circuit. I found out that resister acts to reduce current flow while acting to lower voltage levels within circuits. Therefore, I put five sound buttons, which are like switches, each with a different value of resister so when one button is being pressed, my MechNXT can identify which one is pressed. In order to do that, I need to make something that can identify the current of the circuit and know which specific key is pressed.
Afterward, I spend few weeks making a program that can identify the value of the pressed button. Because I made a program to let the NXT brain know the individual key tone for every value of the resister, sounds will be played from my piano after keys are pressed. At last, there is one port on each circuit board to connect with the four ports on the NXT brain. Because there are only four ports on one NXT brain, I need to make the circuit board larger and fit more key buttons on it so that one NXT port could hold more key tones.
While building, I met some problems too. Firstly, the minimum number of key buttons for playing a whole song should be around 20 key buttons. However, there are only four ports on the NXT. The solution is putting 5 to 10 buttons on each circuit board and connect the four circuit boards to the NXT. Secondly, digital Pianos are too heavy and big to carry around whereas you can construct the mechanical keyboard into any sizes that you want. It can always be extended or shortened since I separate every five semi notes into an independent keyboard.
Therefore, there are a total amount of four main sections to build my MechNXT keyboard. The dominant parts are circuit boards, independent keyboards, a program, and one NXT brain. Some other small parts are some ports to connect with NXT, few cables, and at least 20 buttons.