Looking to see if anyone has built a simple Christmas light controller. Basically a start button to initiate the sequence. Looking to use 2-3 of the popular 16 channel relay modules. Have a LCD as a readout for changing the frequency and duration of the relays staying on. Some sort of external input control to change the values for the frequency and duration. Any ideas? Thanks!
Use a pot for the requency control.
Why not use logic MOSFET, N-channel, at the negative side of the LEDs? Then You don't get the realy clickings.
Was thinking of using this. I’m lost on the code on how to change frequency and duration.
Hi,
Welcome to the forum.
Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.
What model Arduino are you aiming to use?
Thanks.. Tom... 
As Railroader hit on above, if you're planning to do a lot of switching, those relays will drive you bonkers with all the clicking. You will definitely NOT want them in a living area. Personally, I would take his advice and run with it. Switching a single relay a bunch of times per second isn't something a relay is good at either. Or so it has been my experience.
Sorry, No code or Ardunio picked out yet. It does need to have relays though as I’ll be using this unit for other applications. They will not be constantly be switching on and off, more like a one time use thing.
Something to consider is the massive amount of information contained in this thread: LEDs and Multiplexing - Arduino Forum about LED's and flashing lights.
I have benefited greatly from the conversations in the flashing light threads. I now got my own flashing light thingy using an LED strip, the DFRobot Audio Analyzer, and some code. All without the clicky-clicky of relays.