Fritzing

A sample connection, speaker to ESP8266(WEMOS D1) with resistors included

The sample it's based on WEMOS D1 (ESP8266), the speaker has an inmpedance of 8 Ohms and the resistors are 200 Ohm and 100 Ohm in serial, due the amount of consumption in mAh is 10,71 mAh (aprox), avoid overloading the digital pin on ESP8266 (maximum 12 mAh).

The code sample only emit a sound every second to test, but sufficient to validate the circuit

Really is a very simple project, but helps me to studying which are the resistances necessary to add to the circuit. 

Enjoy!!!!