Voltage fluctuation always occurs in electrical supply system. Due to voltage fluctuation, life of electrical equipment consumed electricity is shorted really. To solve this problem, automatic voltage stabilizer is needed for domestic and industries. Both single phase and three phases are available. In this journal intend to known that automatic voltage stabilizer plays efficient role in all type of load i.e. resistive, inductive and capacitive loads. This journal present control circuit for automatic voltage stabilizer provides voltage comparator, relays and servo controlled motor that compare instantaneous input and output voltage. Automatic voltage stabilizer consists of two unit; measuring unit and regulating unit. In this stabilizer, toroidal type variable auto transformer is used for regulating unit and electronic control circuit is used for sensing unit. Electromechanical or servo control system is used for measuring unit to sense the supply voltage. This electronic control circuit will operate within the fluctuation range from 120V to 250V.The rating of this automatic voltage stabilizer is 7kVA (single phase) and its frequency range is 50Hz. The output sensitivity is ±1%. If input voltage is lower than 120V or higher than 250V, the system will be automatic shutdown. The main purpose of this research is design calculation of control circuit