Memlody Music Box
Creator: Zhaorui Wang
Supervisor: Peter Yeadon
Memlody is a music box that can alter itself to play different melodies. The drum is made out of two layers of metal. The outer layer is made out of shape memory alloy (SMA). The SMA changes shape in response to heat, flipping certain pin units to control which notes are being played on the comb. The inner copper layer, which conducts electricity and also acts as a bias spring, manages the position of each pin unit when the SMA is cool.
Underneath the comb and right next to the drum, there is a row of electrodes that brush through each pin on the surface of the drum, and heat up certain pins through the conduction of electricity. The ones that are heated up will flip inwards; the remaining cool ones will then hit the comb and make sounds, all of which will be controlled by a chip in the circuit board.
The challenge in this project is to control the temperature of the SMA accurately. Depending on the diameter and speed of the drum, the activation temperature has to be low enough to allow for the SMA to cool down during the given rotational timeframe, but also has to be high enough to make sure the process is not ambient room temperature.
This is something that requires extensive experiments. One solution might be to train the SMA to “overfold” the pins slightly, which means the activation temperature could be reduced a little but still allows for a desired amount of change in shape.