We build a simple digital voltmeter
using a popular IC for voltage measurement namely ICL7107/CS7107. Using ICL7107, we can build accurate and very low cost voltmeter. ICL7107 is a 3.5 digit analog to digital converter (ADC) which consumes very low power. The IC has internal circuit for driving four seven segment display to display the measured voltage. It also has a clock circuit and a reference voltage source.