This video shows how to use an AC light dimmer to control an AC bulb using an AC dimmer and an Arduino.

I opened the sketch File>Examples>RBDdimmer>SerialMonitorDim, where you can control the light from the command line of the Serial Monitor. But, due to an issue explained in the video, it does not work properly, and the code needed to be modified. It might work in regions with 50Hz, which I have not tested.

Resources for this sketch