I'm planning on building some dimmable lighting controller for Christmas lights, but with LEDs being all the rage nowadays, I was thinking that instead of using triacs and dimming at 60/120 Hz, rectify the AC to DC and use MOSFETs to reduce the strobing that is more evident in LEDs. This might allow the controller to be smaller and/or cheaper.
This would depend on how the LED strings are actually wired up. I don't currently have any to look at, and I could imagine a few different ways they might be connected, such as diodes that only conduct for half the cycle, which would axe the DC idea if true.
Best Answer
LED Christmas lights are wired in series to "gobble" up the 110V applied to them. A great site to read up on this is here.