Syncing Two Strands Of G35 Christmas Lights


For a few years now, the set of Christmas lights most wanted by hackers and makers the world over is the GE G35 color changing set. With 50 individual RGB LEDs controlled by a microcontroller, these light strings can display any pattern of lights with the help of something as simple as an Arduino. The stock light sequences are a little problematic, especially if you’re running more than one string.

[Todd] picked up two G35 strings, and even when they’re turned on at the same time the light sequences slowly go out of sync after a half hour or so. He came up with a great way to make sure these lights stay in sync that requires only a slight modification. To make two light strings stay in sync, it’s simply a matter of disconnecting the data line from one string’s controllers and bridging that connection with the other string.

It’s a very easy modification, but it won’t give you twice as many individually controllable LEDs – for that, you’ll have to use either multiple Arduinos or buy a longer RGB LED strip. Still, having two identical 7×7 LED panels is better than a single panel, so we’ll have to tip our hat to [Todd] for this one.

6 thoughts on “Syncing Two Strands Of G35 Christmas Lights

  1. Running two strings in parallel off the same bus? Not really a high level hack… Build an analog PLL based timing circuit to sync the clocks and I’ll be impressed.

    Also, the data bus is self clocked….why would you need two micros to pull this off? More like two pins.

    1. Well, in the actual post he has links to people that have completely replaced the controller with an Arduino or reverse-engineered its radio and its data bus.

      All he wanted to do was keep them synced, and he found a way to do it that was eminently simple and effective.

    2. Well aren’t YOU a hardass?

      On another note, anywhere an average European could get this or a similar product at a fair price?
      Can’t find the exact same product without going overseas according to my own search.
      And as usual, then shipping becomes expensive, and also import taxes.

    1. I just bought four strings from Costco for $40 each. I do see they are sold on Amazon for $129.50 (yes the same 50 light string). I have just put them up only to find they won’t sync. I thought by plugging only one in at a time and setting them to solid white that when I turned them all on the one remote would scroll them through the 14 set programs. Hoping I can fix this.

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