The nonideal behaviors of liquid mixtures are characterized by excess thermodynamic properties such as excess volumes, enthalpy of mixing, compressibilities etc. The excess dielectric constant ï¥E is also one such parameter that indicates the strength and nature of intermolecular interactions in binary liquidmixtures. The positive deviations fromideal behaviour (ï¥E being positive) are qualitatively attributed to a Âbuild inÂ of components of the mixture in the structure of respective solvent. The negative deviations from ideal behaviour (ï¥E being negative) is explained qualitatively either due to interstitial solvation or due to breaking of aggregates. In the present study, the excess dielectric constants for the binary liquid mixtures (1) benzene + nitrobenzene (2) chlorobenzene + nitrobenzene and (3) cyclohexanone + nitrobenzene aremeasured at 303K and at different concentrations. The dielectric constants for these binary liquid mixtures are measured using a microcontroller based system. The necessary software is developed in C language.