im trying to hook 4 parallel wired LEDs up to a DC power supply that plugs into the wall. its output is 5VDC at 260mA. i plan on adding a resistor so that only 3.5VDC gets to my LEDs. the question is, do i have to be mindful of the 260mA, and if so what can i do to make it suitable for my LEDs? i am getting either 3mm 4000mcd blue and 3mm 6000mcd red LEDs from lsdiodes, or 3mm red/blue dual LEDs from coolerguys. thanks in advance for the help.
First off, your mA figure is too large. Don't look at the maximum current rating, but look at the typical rating, which is 20mA in this case. For resistance, you need (5v-3.5v)/.08A = ~18.75ohms. The wattage rating needs to be at least 1.5*.08 = .12w. So a 22ohm, 1/4w resistor will suffice nicely.
ok so if i got this right the 260mA coming out of the DC convertor is the maximum that can be pulled from it right? so since my leds only pull 20mA that is less by the 260mA and therefor wont draw more than what is supplied. alright thanks for the help thats what i wanted to know.
