I would like to use a CNY70 with arduino that is not 5v but 3.3v powered. On the web there most tutorials use 5v and 200 + 10k resistors (e.g. here and here). So as far as I understand for 3.3v I would have to use lower ones.
Can someone explain how those 200 or 10k were calculated? How could I use CNY70 with 3.3v (if it's possible at all) ?