a fool question

i want to use a RGB led but i dont know if its better to use a common Anode or Cathode ones? iknow how comon cathode works but anode ones? how can i drive them? power should be reversed?

Analog electronics will drive me crazy.

Thanks in advance

It makes little difference which you choose if all you're doing is driving it with an Arduino, just how you connect it and arrange your software. Common anode to 5V rail, cathodes via resistors to output pins, or Common cathode to GND and anodes via resistors to output pins.

Common anode sinks current, so a LOW lights the LED, common cathode sources current, so a HIGH lights the LED.

Many led drivers will actually sink current instead of sourcing current. Therefore a lot of RGB LEDs are common Anode. So you connect the anodes to a common V+ and you switch the cathodes. It will all depend on the circuit you are using to drive your LED's.

[edit]Like the above poster said at the same time ;)[/edit]

ok, i will conect it to arduino, no driver. But if use a comon anode then how can i control the amount of power it will receive?

i'm asking because common anode is cheaper and i want to know how to use them.

Common anode, put the current limiting resistors on each of the cathodes.

ok then is the same than common cathode :S

You'll want to be sure the anodes/cathodes are connected to PWM pins. Then you can analogWrite to them to change the brightness. Just keep in mind if you use a common anode RGB that 255 is off and 0 is full on. With a common cathode 0 is off and 255 is full on.

ok i see