I've tried building this one:
The 5V to 3.3V works fine and I can transmit data from the Uno to the ESP.
I've tried building the 3V to 5V in the diagram and its not working. If I connect the ESP TX to directly to the Uno's RX it works fine - but put it through any kind of level shifter and it stops working.
Also tried building this one - no go.
What level shifters do you guys use that give no issues?