Voltmeter is a measuring instrument, used to measure the voltage difference between two points in electrical network. Generally there are two types of voltmeters - one is analog voltmeter and the other one is digital voltmeter. In analog voltmeter a pointer moves on the scale to represent the voltage. Digital voltmeter directly displays the voltage in digits with the help of analog to digital converter. This article explains you how to design a digital voltmeter using 8051 microcontroller.
This project measures the input voltage from 0V to 5V. Here, the input voltage should be DC voltage to get the accurate output on LCD. If you apply AC voltage as input, then will see the continuous running numbers on LCD as AC varies continuously.