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Author Topic: How does this LED/LED string work?  (Read 674 times)
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I've been trying to figure out this string of battery powered Xmas lights... it's this string specifically http://www.lamplust.com/multi-color-battery-string-lights-wtimer-functions-battery-p-16808.html




I'm a bit new to circuitry in general, but I'm pretty confused about how this string operates — specifically the fact that there three wires connected to the board with the microprocessor (which controls the blink patterns). Why 3 wires? Why do two share the same terminal on a single LED in this photo? I'm guessing the whole thing is two strings braided together but I just can't wrap my head around how these are wired.

Also, could someone explain to me why when I remove the board between the power source (three AAA batteries) and the lights, and just connect the lights to the power source directly — nothing works? (I'm still wrapping my head around how transistors work, but I'm guessing I need one in place for the circuit to work?) If I connect a power source and ground to the contacts on a single LED in the string it will light up, but only that one and not the rest it's connected to...

Maybe a full explanation is a lot to ask for, so even being pointed in the right direction would help greatly — thanks!
« Last Edit: December 11, 2012, 01:04:52 am by awesomerobot » Logged

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I'm a bit new to circuitry in general, but I'm pretty confused about how this string operates — specifically the fact that there three wires connected to the board with the microprocessor (which controls the blink patterns). Why 3 wires?

I'm guessing the lights don't all turn on/off at the same time, there's really two or three strings woven together.

Also, could someone explain to me why when I remove the board between the power source (three AAA batteries) and the lights, and just connect the lights to the power source directly — nothing works?

Three AAA batteries is only enough to light up two LEDs. The board must have a voltage booster circuit on it to raise the battery voltage to whatever's needed for the LED strings (something like a "joule thief").
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Quote
I'm guessing the lights don't all turn on/off at the same time, there's really two or three strings woven together.

They do all turn on at the same time, but it definitely seems like at least two strings woven together

Quote
Three AAA batteries is only enough to light up two LEDs. The board must have a voltage booster circuit on it to raise the battery voltage to whatever's needed for the LED strings (something like a "joule thief").

Yeah, I think that's definitely it — I'm just at the frustrating point where I have a general idea of what to do, but not enough knowledge to know how to do it! I'll get there eventually, Thanks for your help!
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