The output of a thermocouple is generally amplified by an electronic circuit, which has a limited life period. A modified, saturable reactor- or transductor-based circuit has been proposed which has more accuracy than the conventional transductor-based circuit and has a much longer life period than the electronic circuit with much rugged construction and reliability. The theory of operation and the design of this circuit along with its experimental study are reported. From the experimental graphs, very good linearity and repeatability of the circuit with both millivolt input and thermocouple input have been observed. © The Institution of Engineering and Technology 2010.