In the Adafruit Arduino Lesson 10, Pseudo-Theramin, an Arduino Uno is combined with a light-sensitive cadmium sulfide (CdS) photocell to make a light responsive music machine. This project allows you do do the same with an Adafruit Trinket or Gemma mini-microcontroller. This project costs less and works in smaller circuits or wearable projects.

Changes in light intensity on the photocell will change the pitch of a note on the piezo speaker as you wave your hand in front of the cell. While not a true theramin (which uses changes in a circuit's reactance), this project is much simpler to build.
This guide was written for the 'original' Trinket/GEMMA boards, but works with either the original or M0 Gemma. We recommend M0 boards as they're easier to use and more compatible with modern computers!

This guide was first published on Sep 19, 2013. It was last updated on May 18, 2024.

This page (Overview) was last updated on Sep 18, 2013.

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