**Details** The Tibbit is based on the MCP4561 digital POT IC from Microchip. This IC has an 8-bit resolution. Refer to Microchip datasheet for operation details. **LEDs** There is one red and one yellow LED. The red LED is connected to the SCL line of the I2C interface, the yellow LED -- to the SDA line. **Sample project** The use of this Tibbit is illustrated by a Tibbo BASIC test project. Yo can find it here: [https://github.com/tibbotech/CA-Test-Tibbit-40](https://github.com/tibbotech/CA-Test-Tibbit-40).