I have NodeMCU ESP8266N Lolin V3, my 5V relay is powered from Vin of the NodeMCU. The NodeMCU is powered from 5V USB.
My difficulty is when I measure voltage between Vin & GND, it is of 1.9V, but supposed to be around 5V as it is directly attached with usb 5V supply. Actually my relay is not working with the power tapped from Vin, but relay's led & NodeMCU led are blinking but relay coil does not trip. Please confirm is my NodeMCU having problems as voltage between vin & GND read 1.9V. https://drive.google.com/file/d/1Z6jYX4sCLmRxnWbtBYZCNW6LpckokaC9/view?usp=drivesdk