I have an existing project using an Arduino Yun that controls Christmas lights with relays to turn them on/off. There are currently 13 separate rows of lights on the (60 foot) tree, each plugged into a wall wart that's controlled by its own relay.
I'm considering adding the ability to dim the lights, so I wanted to figure out the best way to do it. The lights can all be dimmed "in unison" - there's no need for 13 seperately controlled dimmers. But I have to be mindful not to cause any "buzzing" in the audio equipment on stage where the tree is.
I've read about PWN, zero cross, and other terms and saw the zero cross tail from powerswitchtail.com that seem useful in the typical project. I'd like to be able to pull this off with no more than 2 "dimmers" for the whole project, if possible.
Where do I start, and how do I do it?