The OLED has it's own regulator on the back, so is powered with 5volt (works on 3.3volt too).
The SHT30 board is a 3.3volt model (no regulator or level shifter fitted), so powered from 3.3volt.
The blue LED on the ESP short-flashes in the rythm of the seconds update to the OLED.
I didn't bother connecting a LED to pin 0.
I uploaded with the CPU clock set to 80MHz, hoping for a bit less current draw.
I have it plugged into a USB voltage/current adapter. Current draw is below whet that adapter can detect.
Leo..
