In my case LEDs are connected to a 3.3V power supply by default. Some LEDs does not require a resistors and some does.
Most LEDs works best around 0.020A.
The table below has been tested with an Voltcraft DSP-3005V power regulator. You can also check the resistor calculator, they will correspondent with the table below.
| Color | Working voltage | Resistor |
| Green | 3.3V | None on 3.3V 100Ω on 5V 470Ω on 12V |
| Yellow | 1.9V | 82Ω on 3.3V 180Ω on 5V 560Ω on 12V |
| Red | 1.9V | 82Ω on 3.3V 180Ω on 5V 560Ω on 12V |
| Orange | 1.9V | 82Ω on 3.3V 180Ω on 5V 560Ω on 12V |
| Blue | 3.3V | None on 3.3V 100Ω on 5V 470Ω on 12V |