Wire multiple LEDs in series. Possible?

[FantomXR]

Hey people,

inspired by another thread I'd like to create a pcb which has 3 RGB LEDs (or 9 single LEDs) on it. This PCB could be stacked on top of a encoder and illuminate it. I could cnc mill the caps for it by myself. 
My question is now if it's possible to wire each color in series (so, all blue, all red and all green LEDs) or if the current and / or voltage provided by a DOUT (maybe with ULN installed) is not sufficient to light all three LEDs. 

The reason for this is, that it would be less programming because I only would need to add one string for each color in the NGC instead of three strings. Also it would be less wiring. There is no need to access the LEDs individually.

Thanks!
Chris

[TK.]

Please wait for this until I've checked various RGB LEDs at my side (it's on my Agenda to try this out for upcoming MBCV V2)
I've already the RGB LEDs, just need some time for some experiments - and I will try this with a MBNG.

It might be that I will add special extensions to minimize wiring effort, but to ensure that we've enough dim levels

Best Regards, Thorsten.

Edited October 6, 2015 by TK.

[latigid on]

On a sort-of side note, I've tested both the Bourns and Sparkfun illuminated encoders for brightness. I'd guess both are actually made by Topup corp judging by the very similar packages. The illumination is sufficient when I used some analogue PWM, although I don't have clear "Waldorf" knobs.

It's now a question of this easy solution or a cheaper option with hollow shaft ones. It would be possible to bend a square/flat 5mm RGB LED across a PCB cutout, or maybe there's an SMD version that would fit into the 3 mm hole on the same side of the board.

[FantomXR]

Great! I'll wait for it then ;-)