Sorry I don't understand
"You make a solder-bridge that shorts the regulator if you use 3.3V"
If I understand correctly, the display can work with 3.3V regulated display even If it's better to supply with 5V
As for the Arduino , I don't understand why I don't have any led working with 3.3V from my regulated supply. I understood that If I supply with 3.3V it's connected to VCC and If I want to supply with 5 V it's on the raw entry.
I chose 3.3V to make my life simpler but it's not working :-(.
When you say I must solder the header strip to my Arduino, you mean the 7 connections : VCC,GND,10,11,12,13,8,9) ?
or all of them
thanks