Powering an ESP-01

Just another reminder to myself about how to convert 5V, like provided by Arduino, USB, and any number of wall warts, to 3.3V as needed by the ESP-01 board, using a resistive divider.

It's a little hard to see what's going on. Here is a schematic:

This only shows 2 resistors. In the photo, I'm using 2 1kΩ resistors in series to make 2kΩ resistance. The top yellow wire is Vin, R1 is the left most resistor, which is 1kΩ, R2 is the combination of the right 2 resistors, also both 1kΩ. The formula for the math is



As it turned out for my project, it was actually easier and better to buy one of these:

https://www.amazon.com/gp/product/B01CONBSV0

This power supply module takes 4.5V - 12V as input and outputs 3.3v.