I have ordered the white Optrex LCD from Mouser (as noted in the Ambika BOM):
The instruction for the ambika main board assembly is telling me that I need a 100 ohm resistor for the green Optrex LCD. Is it the same for the white LCD? Could I just try it savely with a 100 Ohm resitor?
Here is the data sheet of the white LCD:
Sorry for being overcautiously 
Yes, that one to needs the 100Ohm resistor.
I have this display too. It’s black letters on a white background… But by white they actually mean grey. It is supposed to be used with a 100 ohm resistor. But i found it really dim. i think i used 10 or something… but you can safely go to 50 ohm
Great. Thanks a lot for your fast replies!
Well… there is a picture of my ambika in the successful builds thread… The whole story is that i first too calculated it to be 100 ohm. I’m using a grey case and wanted the display to break to the dark plexi. So i was a bit disappointed to find it very grey and dim and it looked it could be a lot brighter. So i started testing lower and lower resistance. When i was down to 5 ohm i thought… well f%^ck this doesn’t need a resistor at all. So i tried shorting the connection for a very brief moment but i noticed this was not good 
… So one of my leds burned i think cause the display is a little dark on one side. But now i’m using something like 10 ohm… It works but i takes a lot more power. My ambika doesn’t work on a 1000mA adapter… i’m probably using something like 1250mA and it get pretty hot…
I like the display and it’s very clear and readable under all conditions. But after i’ve seen what a transmissive display does in a grey plexi case like on the sonic potions LXR i’d rather want a white on black display.
I’m sure the red Ambika above my post is using the same display and you see what it looks like with a 100 ohm through a clear window.
It looks cool.