Optoisolated Xmas Light Control

[buzzkill] brought this crazy christmas light controller to my attention. The hack is pretty neat. The potiometers in several standard dimmers were replaced with photo-resistors. When squares of the screen are lit, the dimmer is activated. In essence, it’s a cheap optoisolator for controlling AC power. The software that generates the interface appears to be sound actuated once it’s programmed by the user.

11 thoughts on “Optoisolated Xmas Light Control

  1. So thats how that lighting on that guys house was done was done….I had wondered since Xmas last year when I saw it..There’sa video somewhere on youtube of it. It’s a pretty unconventional control method but I like it….


    I half-assed it last year(2006) with some car relays and the 8 port serial relay box and qbasic4.5

    needless to say actual “programs” were choppy. and at ~$3.5 per outlet, I’ll be giving this a shot this year and piss the neighbors off even more.

    The best thing about computer controlled lights, is adaptability. Going out of town for a week, hook a few table lamps upto the box and turn on different rooms at +/-30 minutes each day… or at new years make the lights count the last 60 seconds and then go crazy nuts at midnight… I love these things.. .

    About the project, I love it and hope to see some improvement!!!

  3. This hack is certainly interesting, but not the “normal” way of doing things. Personally I love the concept and it is the very definition of a hack. But it is hard to scale in that as you can see from the photos that as you add dimmers and outlets it takes up a lot of room. He also mentions that variations in the dimmer components and the photo-resistors themselves lead to inconsistant results. Some lights don’t turn on. Some never turn off. For a more scalable solution that is still DIY check out Computer Christmas. Many etch their own controller boards and the forums are pretty active with new circuit designs and board layouts. The easiest solution is on/off only. But they are quickly working on a dimmable option that should be ready in time for christmas 07.

  4. hey, that idea rocks! unfortunately we (my family) live in germany where these masses of lights on the house aren’t very common… maybe i’ll use this technique for building a cheap and simple light control for party rooms… if i do so, i’ll write a software in vb and let you know ;)


  5. Ha, I did something like this back in 98, using exactly the same idea, I figured out doing it after my brother showed me his casio “datawatch” or some thingamajig. The device used the computer as an authoritative source for data, I think it had basic scheduling and stuff, and to sync it you held it up to the screen over these two blinking squares, you could tell one was a clock signal and the other was data. Slick Idea really – a real hack – totally in the spirit of hacking.

  6. this is DANGEROUS. Normal wall switch dimmers have no electrical isolation between the potentiometer and line voltage. Using a wall dimmer in this manner exposes the telephone wiring he is using to line voltage, and also creates a severe fire hazard since all of that 24ga wire is protected by a 15 or 20 amp breaker. The safe way to do this would be to use a triac, optocoupler, and related circuitry. While a bit more expensive than this method, it’s much cheaper than causing a fire or causing bodily injury to someone.

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