There are many ways of building a theremin, from kits that are available online or from creating a handmade theremin with objects like the Wiimote. To start with the basics, I explored a simple example which uses two phototransistors and a small speaker. The way that it works is very simple, and a provides a good starting point. This is essentially a basic theremin that uses light and can also be ‘played’ by moving one’s hands closer or farther away. The input taken from the phototransistors as light is converted into current and outputed through speakers.