Arduino Christmas light project with dimmer 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?
I can think of a couple of ways to approach this:


Use a DMX dimmer, something like this 4-channel dimmer, or
Use an household X10 dimmer.


DMX is used for stage lighting and there is some information on controlling DMX devices with an Arduino in the Playground where there is also some information on the hardware interface and shields, it looks pretty simple. DMX is a differential RS485 interface.

X10 is used for home automation, the signaling is done over the AC line. There is some information on using X10 and an Arduino library in the Tutorials.

Both seem like viable approaches, if you're working in a theater it is likely that they might already have DMX equipment and it would be as simple as hooking up to the gear in the house. Then you'd only need to add a shield or build the interface hardware.