I am using a uln2803a transistor array to drive a LED series ( 2 ) . The LEDs are 5 mm LED. blue and white. This is using 6 pins total of 12 LEDs of the uln2803a . The. What is recommended for the current limiting resistor for the LEDs ( 12 volt is the source ), ? I was using 200 ohm resistors ( 1/4 watt ). There is some heat i am noticing. Do i need to use 1/2 watt resistor instead? This will be in a closed box with little air flow.
The uln2803a is driven by a Arduino Nano using PWM /digitical pins ( 6 of them ) to the uln2803a–not sure if that is relevant or not.
Thanks for any guidance here. If i need to explain more I will. Will throw together a diagram if needed. Hopefully it is just some math i need to work through.