I’ve just received my ESP8266 expansion IO board but the pcb didn’t embed the 3.3V regulator (as expected according to the pictures from the eBay seller) 😦
As I have plenty of 5V, 9V and 12V salvaged power supplies laying around (and not a single 3.3V), I was very interested to use them with my ESP8266 ESP-07 module…
It was not a big deal to find out the needed regulator (with compatible pinout) but, as Google was not my friend this time, the operation deserves a few lines of blogging with IC reference… 🙂
The ‘trick’ is to remove the 0 Ohm shunt resistor (which directly connects the VCC pin of the adapter board to the VCC of the ESP module VCC when not using a voltage regulator).
Once this resistor unsoldered, the VCC pin of the expansion board provides power supply to the voltage regulator (to be soldered on the back).
I chose the AP1115BY33G-13 LDO (low dropout) regulator which I found to be cheap (0.3 €) and easy to buy (RS, Mouser, Digi-Key, Farnell, …). Here is a link to the datasheet.