# 5mm LED Christmas Lights



## bhds (Oct 6, 2013)

Anyone have any experience with them? 
Last year was my first experience with LED xmas lights. I strung about 8 strings of C9 bulbs and while it was nice to plug 4 or 5 strings together without burning my house down, I wasn't very happy with the looks of them.:ironic:


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## Oznog (Oct 17, 2013)

You may notice a "flicker"... to say the least.

The thing is, most strings are NOTHING but a BUNCH in series and a resistor. It's not just that it rises and falls 120 times a sec like fluorescent- no, it has no bridge rectifier. It actually turns on and off at 60 cycles/sec and is completely "off" for MORE that half the cycle. 

You may think "I'll just include a fullwave bridge and capacitor", but the LED forward current was CHOSEN with the idea of a ~60% off-time, and the time it IS on expects a rise to a peak of 170V- put a cap on it and it'll get a constant 170VDC. They'll be overloaded.

I was working on a design to hack this a bit and give it a constant-current DC drive. Maybe more work than it should be, but... I do hate the flicker. A lot. I do like the Christmas lights LOOK, and incans are not only expensive to run, they tend to start burning out bulbs one by one within a few hundred hrs.


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## Canuke (Nov 19, 2013)

The trick with any rectifier or DC setup is that often some strings have the LED's in 30-35 unit "banks" that aren't in phase, forcing you to cut and rewire.

My thought for a "flicker fixer" would be to use a higher frequency AC wave, but I imagine that such a device, especially if it produced a square wave or "modified" sine wave like the cheap inverters, would be really noisy.


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## Changchung (Nov 26, 2013)

Great, my posts start to disappear...


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