Computer Controlled Christmas 2009

Well it’s that time again already, Christmas is on our doorstep. During the month of November we begin putting up all our lights as it is no small task. Unpacking lights from last year can sometimes be a tangled mess, once that’s sorted all lights move onto the testing stage. Last few years I have been using mostly incandescent globes, and a few LED strings. Only problem with globes is their tendency to stop working, and are easily broken. Its a tedious task at best trying to find a bad bulb in a section, to add to that try being in the roof at dusk. Time to wheel in the wheelie-bin! In go all the incandescent light strings, it’s time to upgrade to LED. I had been holding off switching to LED’s as in past years they had been quite expensive, this year they were much more affordable, every dollar saved matters when you’re buying 20+ sets of strings 😛

LED’s can be controlled by using my 240AC switching logic, but that means lots of unnecessary transformers. So this year I’m using a lower voltage switching board, which can operate up to 60vDC. The board has 16 outputs and is powered by a 350w 36vDC power supply, this supply powers ALL the LED’s. Downside to this is some LED strings come with a multi-function controller that take 240VAC input and provide a crude ~24VDC output. As I’m using a DC power supply I have to remove this controller and feed the DC directly into the light strings. Problem two is that depending on the combination of colours of the LED’s, the requited power could be anywhere between 24v ~ 30v, hence the reason I’m using a 36v power supply.

While the LED’s will operate on a full 36v, they will quickly die. So the solution is to add a resistor/s into the string to limit the voltage to the required amount. The current through each LED is circa 10mA, some colours can require up to 15mA, I’ve checked all my strings and Im quite happy with the brightness at 10mA. So once I’ve calculated the resistor size its time to solider and heat shrink it onto the string.

 

All ready to go! I’ve completed modifying all my strings and have hooked them up to the controller. I’ll be putting the controller in a better enclosure next year, it will do for now 🙂

I’ve only got a few more things left to do before the Dec 1st switch on date, ill do my best to post a video up shortly.

Wishing everyone a very happy and safe Christmas!

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