I'm just starting with arduino, and want to light up 2 RGB leds (common cathode), and just think that the only thing I nedd was connecting them in parallel, no extra parts (my mistake), then I read about the max current of the ardunino pins, and found out about driving leds with transistors.
I have been reading about this in here and al around the web (can't post more :p ), my set up is simpler, just 2 leds in parallel, but I want to make sure I won't blow up my ardunino.
When I was driving one led directly from the arduino, I was using HIGH to turn on de led, now I will have to change the logic to light de leds on LOW.
First, is this set up correct? and Second there is a simple way to drive de 2 leds.
Each pwm pins in the ardunino (9, 10 and 11) connect to base on each of the NPN transitors (one per color), emmiter of all transistors go to 5v, and collector of each transistor go to respective color on both leds. Common cathode on both leds go to ground.
I plan to use 2N3906 transistor for this.