I am trying to make a small project using Nodemcu. My project is WiFi controlled LED, 2 LED's will blink at the same time. I have successfully uploaded the code and it works fine using USB connection. But I want to power the Nodemcu using 12 volts 1.5 amps AC to DC adapter. I have checked it in web search but I have not found an understanding circuit. please help me out guys.
You connect the + side of the adapter to VIN pin and the - side to GND.
You have to check the maximum voltage when using the VIN pin. Probably it means you 'waste' some power (but it's from a wall wart, so it should be ok). See the remark of Flyingfenix below for heating consequences.
See this link: Power Related ESP-12E Development Board Pins, fragment 'Using a Wall Wart':
The current (1.5A) should be more than enough; the adapter's current should be higher than what is needed by the NodeMCU + circuit. So this is ok.