Got my led's today. Questions

[PESteele 10+ year member]

i got them today but they also came with ten 390 ohm resistiors. Am i supposed to use the resistiors when using it w/ 12 volt or something. im confused. any help would be appreciated

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[audiobahnuser18 5,000+ posts]

It's optional really

 

[yacob.naif 10+ year member]

it's mandatory for led zeppelins

 

[PESteele 10+ year member]

does it do anything. Will it hurt the led's be not using them. Also if i was to use it would i just wire it inline with the posative

 

[PESteele 10+ year member]

it's mandatory for led zeppelins

nice

 

[PESteele 10+ year member]

bump need help

 

[Worlddre 5,000+ posts]

led generaly require a certain voltage in order to function...the resistor is to drop the voltage to that required voltage...

 

[acold7dusta 10+ year member]

say they're 3v LED's, you cant just put 12v through them. they'll light up very bright for less than a second and then burn up. use the resistors, theyre there for a reason

 

[Worlddre 5,000+ posts]

there is a resistor calculator somewhere on the interweb that will do all the math and such for you

 

[phantom240 5,000+ posts]

Or if theyre like 3v, use 4 in series. 2v, use 6... and so on.

 

[enzowho 10+ year member]

say they're 3v LED's, you cant just put 12v through them. they'll light up very bright for less than a second and then burn up. use the resistors, theyre there for a reason

The resistor is used to control the current through the LED's. You can determine your current value by ohms law. Lets say you are connecting three, 3 volt LED's use the following eq. 12V-9V/Needed Current = R. (Your current is probably like 10mA or something small like that.) The 9 volts comes from the fact that you have 3 LED's each with a 3V drop.

 

[phantom240 5,000+ posts]

...or you could just think of em like sub coils... 4ohm + 4ohm series = 8 ohm. 3v + 3v + 3v +3v series = 12v ftw

 

[bigwheel15 10+ year member]

there is a resistor calculator somewhere on the interweb that will do all the math and such for you

http://led.linear1.org/1led.wiz

http://led.linear1.org/led.wiz

Are those them?

 

[disturbedfuel15 10+ year member]

^ Yup, those are the calculators. You'll see they are all pretty much the same across the web, ones just look fancier than others or use bigger words //content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif I've always used this website http://www.metku.net/index.html?path=mods/ledcalc/index_eng

By the way, blowing up LEDs is fun. I first expirienced the thrill when I hooked up and LED and resistor to 12v instead of 3.3v on accident.

 

[BoomBoomBoy 10+ year member]

bump need help

Wire it inline on the anode or you'll burn out the LED w/12V. I usually solder it to the anode and then to the (+) wire. Then slip a pc. of heat shrink over it to protect it.