ESP8266: 3,3V or 5V

According to the secs the ESP8266 should be powered with 3,3V and the RX line should be 3,3V.

I have seen lots of postings from people saying they run this device since month now 24/7 with 5V. No problems.

What are your experiences with the ESP8266?

It is designed to work properly with 3.3v, so I only supply 3.3v.
Might work with 5v "no problems" from a human perspective, but whats going on internally is a different story. Definitively stressing the components until one day poof the magic smoke wafts through the air.

OK I am a beginner and I'm trying to lean. Mostly from the Internet.

But there are some strange sketches out there ...

  • Why would one connect 3V3 and 5V from both Arduinos together?
  • Why put a 220Ohm resistor between TX(ESP8266) and RX(Arduino). Should this be some kind of (failed) voltage devider? If so, shouldn't it between TX(Arduino) and RX(ESP8266)?

Have you tried asking the person who generated the diagrams?

@zoomkat @Zealot You probably found it out already, but the chip is 3.3V only, but RX and TX are 5V tolerant, so you can safely use it with a 5V Arduino as long as you only supply 3.3V to the power pin on the ESP8266 module.