I read some guide that claimed that around 330Ω resistors were needed, but the small board I have has one 33Ω resistor per each two leds.
The color stripes of the resistors are orange, orange, black which I understand to be 33Ω, I also measured them and got 33.4Ω.
I realized that my multimeter could measure the forward voltage, and I got 1.63V. Then I would get (3.3V - 2*1.63V)/0.016 = 25Ω. Or in reverse with a 33Ω resistor the current would be 12mA if I have understood this correctly.
Will that be fine?
( I am also a bit worried about that it being two LED in series, with what I measured 3.3V-2*VF is rather close to 0. )