Hello I'm currently planning on using 4 LEDs for my project, which I will hook up to an Arduino Uno. Being new to all this I want to make sure that I've gotten the numbers correctly.
Do I need 3 resistors for each LED?
According to the Datasheet for the LEDs https://www.sparkfun.com/products/10820
this is what I've calculated:
Forward Voltage: 2.2V (Red), 3.4V (Green & Blue)
Forward Current: 20mA (For Red, Green and Blue)
I'm assuming that since I'll be using a wall DC charger for the Arduino (9V DC), that the source voltage is 9V.
I'm using this calculator to calculate the ohms: http://led.linear1.org/1led.wiz
Based off of my calculations Am I correct?
- 4x 390ohms, 1/2W (The wizard recommends a 1/2W or greater 390 ohm resistor. The color code for 390 ohms is orange white brown). <-- That's for the red value.
- 8x 330ohms, 1/4W (The wizard recommends a 1/4W or greater 330 ohm resistor. The color code for 330 ohms is orange orange brown.) <-- That's for the green and blue values. Would these work: https://www.sparkfun.com/products/8377
I've looked for them on sparkfun but I can't find any 390ohm resistors. Does anyone know where to find them or a better alternative? Thanks!