Strictly speaking, a Theremin uses a pair of antennae that act as capacitors in a specific R/C circuit. Looking at ...

The MCP_POT library implements access to MCP digital potentiometers. These devices have 1 or 2 potentiometers, 10 KΩ, 50 KΩ and 100 KΩ and communicates over SPI. The library supports both hardware SPI ...