# Can LED Christmas Lights Run Off Low Voltage Yard Lights?



## gonediesel (Nov 27, 2009)

Hey guys my wife has been bugging me to hang Christmas lights for several years. I have a 3 year old and she keeps asking for lights. So if I do this I will go LED. I do not have a set in hand but was wondering if I could tie LED Christmas lights into my low voltage yard lights. Anyone mess around with this kind of project?


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## Al Combs (Nov 27, 2009)

:welcome:

I'm pretty sure the ones you buy in the store are wired in series, a.k.a. high voltage. The reason they need to be in series is because the red LED's need about 1 volt lower than the other colors. You usually have to go in series to drive multiple LED's anyway, but especially in this case. If they were all wired in parallel and you measured the current at the brightest LED while you tweaked your voltage regulator, the red would be very bright while the blue and green wouldn't even be lit. With everything in series you only need an ≈ 15ma constant current regulator.

In a homemade string you could parallel all the LED's of various colors and put the different color string in series. Say a 20 string of 5 white, 5 red, 5 green and 5 blue would be wired 4S5P. But that would be 5 wires in a string and way too much work.:thumbsdow

I never actually owned a string of LED lights. I wanted to buy some online once and changed my mind after reading the customer reviews. Mostly things like after spending twice as much as a normal string of lights, they didn't make it through the first season. That made sense to me since most of the time a normal string goes bad from contact problems in the socket, not the bulb itself. A string of LED Christmas lights are probably more reliable all other things being equal because they generate less heat. Less heat would cause less oxidation. I don't know how much that actually helps since even when they're new, those $3 Chinese Christmas lights have brown copper contacts like a 30 year old penny.:santa:


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## StarHalo (Nov 27, 2009)

Philips now has a whole range of solar-powered LED christmas lights available in a few different stores; a small solar panel is attached to a length of lights/icicles/net/ornament, you just set the panel so it gets some sun and arrange the lights per usual, no power cord, nothing connected to anything else.


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## Ken_McE (Nov 28, 2009)

What is the voltage of the yard lights?


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