Rep Power: 248

Oh im using these values to find resistance:
Supply=14V
Voltage Drop=2.2V
Current=20mA
w/ 3 LEDS
and im getting a resistance of 260 Ohms
are these values good?

 
Rep Power: 813

well, the car normally puts out 14.4v typical, but there are also times when warming up (esp in cold weather) where it reaches 15.5v so i always do mine around 15-16 to be safe. 14 is way too risky. its better to sacrifice a lil brightness to make them last longer.

 
Rep Power: 248

ok so ill use 15.5V. i live in central cali and it doesnt get below 30 so it shouldnt be that much of a problem. should i go ahead and use 20mA in the calculations or use 15mA for the 3mm LEDs?

 
Rep Power: 813

well the led specs should tell what it is. i know most 5mm are 20mA. never used the 3mm.

 
Rep Power: 248

it never gave anything, but a constant max of 30mA and a max of 75mA. i went by radio shack and their 3mm LEDs are rated at 15mA so i think i will use that value. i know the resistor has to be soldered to the anode (positive) side of the LED, but does it matter what end of the resistor is soldered to the LED? i dont think it does but just checking

 
Rep Power: 292

no. resistors aren't polarized

 
Rep Power: 0

ok, so i got my LED's and resistrs last week - but i was too busy to do anything. Tonight after work I got started and if my way works (kinda of a play off gearbox's version) I'll write a DIY for it.

only issue right now is i dont know the resistance of the resistors that they sent because they didnt label them like they did with the LED's

Blue 7000mcd 5mm
Wavelength:460-470
MCD:5000-7000
Vf(V): 3-3.4
Degree:20
is whats labeled on the bag for the LED's

oh, and gearbox - how many resistors/and what resistance, resistors did you finally end up using?
I know the color bars on the resistors help identify the #, but i cant find anything to help determine the resistance - here are the color if anyone happens to know:yellow,orange, looks like black, dark green, and dark brown?

 
Rep Power: 292

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