But I miss RN1 & RN2 too. I suppose they are resistors networks 4k7.
Exactly. Just install 4k7 resistors here.
Also, can you describe a story with photo resistor? I miss that too, but I see on the BOM's something about it's optional. I would like to have it so please let me know what value I'm looking for and do I have to miss some other resistor in that case?
Photoresistor used as brightness controll for 7-seg display.
No brightness controll: use 3k3 (brighter).....8k2(dim) resistor at the place of R20, ommit photoresistor and R21.
For me, optimal value is 5k6.
If you want to use brightness controll option, install R20,21 and use photoresistor-
allmost everything will work here... Roff >100k, Ron 0.3...2k.