0 to 25V Voltage Sensor, 3 Terminal Sensor Module 2pcs

Principle:These are not really 'sensors' per se, but actually just a 7.5K+30K ohm voltage divider to make it safe for your to read up to 25V(or your ESP8266 to read up to 5V).Advantage:This module already come pre-built, can be mounted through a bolt/screw to any surface, and have terminals already set up for your application.You can find example codes all over the internet for using this, but the basic formula is voltage output = voltage input * (R2/(R1+R2)), where R1 is 30K and R2 is 7.5K.Note:If you're really looking for even greater accuracy, you should take a calibrated multimeter and measure the resistance of each of the tiny resistors on the board sensors, since they each have a bit of variance from stated 7.5 and 30K ohms. Then just adjust those numbers in your code.Application:It gives a very close to perfect 1/5th of the voltage sensed. This module is perfect for when you want to measure something higher than VCC on an electronics project.Specification:VCC: DC input, positiv