User:Rob Kam/sandbox1/Talk:LED

• https://learn.sparkfun.com/tutorials/light-emitting-diodes-leds/introduction

How to choose a perfect resistor to LEDs to get same brightness?

You can only calculate this if you have bought LEDs that have been 'binned' (selected, sorted) to particular brightness bands. Randomly bought LEDs can cover such a wide range of brightness that all you can do is adjust the resistors until they look matched. https://electronics.stackexchange.com/questions/554586/how-to-choose-a-perfect-resistor-to-leds-to-get-same-brightness