just smoke some leds

Pandaram · May 8, 2012

HI GUYS.. afternoon..

the shop i bought the trancefomer, said i dont need resistors.. but when i solder 10, 1w led in parrallel and switch the power.. its gone in smoke..

i am tryin to build a led unit with 10, 1w led in parallel line AND a 5, 1w led in parallel line

**********10x1w

*****5x1w

using 40w 12v trancefomer.. leds r 3.2v . 350mA . 1W.

what is the best way to build it? thanks..

Pandaram · May 8, 2012

27ohms.. but do i need 3+w for each led?

how about resistor for eash lines.. 10 and 5?

ev13wt · May 8, 2012

You need 3.2V, not 12. No wonder they broke.

Correct me if I'm wrong.

How did you connect them?

Slickseth · May 8, 2012

If you wired them parallel then you gave them nearly 4 times too much voltage. You need to wire them with 3 in series and a resistor to drop the excess voltage.

eh4 · May 9, 2012

I don't know much, but I've read that if you wire them in parallel, then Each One needs it's own resistor, if you have them share a resistor then irregularities among the leds will lead to some bearing more current than others... if one of them blows then the rest will get the additional current, and then another blows, add current, etc. etc.

Pandaram · May 9, 2012

ev13wt said:
You need 3.2V, not 12. No wonder they broke.

Correct me if I'm wrong.

How did you connect them?

thanks mate i just order some dc to dc step down trasfomers.. hopefully it will do the trick..

Pandaram · May 9, 2012

thanks for the input guys.. do me lots of good..

Cataract · May 10, 2012

eh4 said:
I don't know much, but I've read that if you wire them in parallel, then Each One needs it's own resistor, if you have them share a resistor then irregularities among the leds will lead to some bearing more current than others... if one of them blows then the rest will get the additional current, and then another blows, add current, etc. etc.

Not quite 100% correct. Yes some LED's might conduct more current, but you can take out as many as you want, it won't change how much current will go through the other LED's. So, if one burns, the others won't care and you'll be pulling less overall current. If you put more LED's, you'll pull more overall current and then you might burn the one resistor, so the choice in resistor has to be calculated according to how many watts you are pulling.

DUQ · May 13, 2012

Pandaram, please get the program listed here ---> http://www.candlepowerforums.com/vb/showthread.php?31388-Introducing-the-LED-Pro-Modders-Program

yellow · May 14, 2012

With that power supply You do:

THREE of the led in series + 2.5 Ohms resitor in series, all hooked to the supply.

works for 9 such "strings"

just smoke some leds

Pandaram

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