Water quality analyzer

A water quality analyzer, comprising:

• a pair of sensor electrodes that are made of different metals from each other and are soaked in water and used, the sensor electrodes generating a sense voltage across the electrodes in proportion to concentration of impurities included in the water;
• a detection means that detects concentration of solute from a voltage value of the sense voltage to provide a detection result;
• an impedance element that is connected between the sensor electrodes, and having an impedance value which is a resistance value that can improve non-linearity of the sense voltage;
• an offset voltage supply means that superposes an offset voltage on the sense voltage;
• and
• an amplification means that amplifies a voltage obtained by superposing the offset voltage on the sense voltage at a prescribed gain to provide for the detection means, wherein the above detection means detects the concentration of solute based on a voltage value of an input voltage from the amplification means;
• and
• a setting means that provides a calibration mode of the sense voltage and sets the offset voltage and the gain so that with the sensor electrodes soaked in a liquid of reference concentration, the sense voltage generated across the sensor electrodes agrees with a reference voltage corresponding to the above reference concentration in the calibration mode.