well i just bought those $10 blue led witht he cigarette lighter plug to tape on to my dash last week, but yesterday, one of them became hella dim and the other one remains bright. Anybody know why? I thought led bulbs dont burned out...... (sorry if this topic doesnt belong in this section, but i have no idea where else i can put it)

 

they do burn out, not very quick, usually last for tens of thousands of hours, possibly the voltage from the cig lighter was too high, LED's, especially blue, are very sensitive to over and under voltage

 

but the other one which is also connected to the same plug still works tho.

 

grab a multi-meter, check the voltages at the dim LED

if you only bought them last week, just take it back to where you got it from, tell them they sold you a piece of ****, and get a replacement

 

i wish i could take it back but i buoght it during my trip to canada and im back to california right now.....

 

okay i checked the voltage, the dim one has 2V going thru it after the resistor and 12V before it, but the bright one has 4V going thru it after the resistor

 

ummm you prob just have a bad LED... It happens... LED feeds more on current then voltage.... but that should cause one to go bad... you could try replacing the LED.... ceck the value of the resistors maybe their wrong... but it's prob a bad LED.....look at the LED... does it have any discoloration inside where the the light is emmitted?

 

no the dim led looks exactly like the good one, cant really tell any differences visually. And i dont know where i can get 1 led with 1 resistor..... cuz on ebay they are usually in package of 10 or 20 which i really dont need that much..... what does the resistor do? just step the voltage down? maybe its resisting too much current so not enough current is passed thru?? i dont know anything about these led thing, what do they look like when they are burned out? like darkened on the inside surface?