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I need to string together to lines of 6 Led bulbs each together the leds I bought came with resistors but I see projects that don't or I can't see any resistors so My question is do I need to put resistors in the string or before each bulb or...and can I run 6 leds with a battery?like 2 AA's or a 9 volt or something. or go with a hard wired 5V transformer type plug in?
 

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If you solder the leds without a resistor, you run the risk of blowing out the leds.
Depending on the voltage, some leds are more sensitive then others. I soldered a string of them together once before w/ resistors to each one, powered by two 6 volt square batteries wired together in a series. Local Radio Shack would be able to help you with any questions.
 

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you always need a resistor for limiting the LED current. If the LEDs are wired in series, you only need one resistor. If they're in parallel, you'll need one per LED. It looks as though your LEDs are already prepped to be in parallel, so I'd run with that (wire each LED/resistor unit to the supply, directly).

With regards to the voltage and supply source, the pre-made LED resistor combos I've seen have been for +12v. You should verify this for your LEDs, if you can. Alternatively, if you can see the resistor color bands, decode these using a resistor decoder, and plug in to this forumla... V = 1.7 + (.02) * R, and this should get you close.

If the resistors were chosen for +12v supply, (2) AA's won't cut it. That's only 3v.

- Hook
 

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It depends on the LED, find out the voltage, use the calculator link. If you have them in series. It is a myth that you absolutely need a resistor. If you go the the doller ( no time for spell check) store and get some 3 volt disk type batteries they should power the leds all night at aBOUT $.50 each. research throwies on the net. But you need one battery per LED.
 
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