In order to control the temperature of the furnace precisely and to study the mass variation of the substance with
respect to temperature, it is essential to read the temperature of the furnace and temperature of the substance. Here the substance (sample bucket) is suspended inside the ceramic cylindrical tube over which the heating coil is
wounded. The heat experienced by the substance inside the thermobalance is due to the radiation, because of which there is a temperature gradient between the walls of the furnace and the substance. In order to carry out the experiment in synchronization between the temperatures of the sample and the sample mass variation, two thermocouples are used, one to measure temperature of the furnace and other to measure temperature of the sample. In this application the maximum temperature that will be measured is around 1000 _C. PIC16F877A microcontroller used is having 10 bit internal ADC with 5 V reference. Therefore its resolution will be 4.87 mV (_5 mV).The thermocouple used is Kanthal type thermocouple which is having the resolution of 40 lV/_C and it has to be amplified to 5 mV/_C. Therefore
outputs of the thermocouples are amplified by the amplifiers constructed using op-amp op07 designed for a gain of 125 (5 m/40 l) (Figs. 5 and 6). The output of the thermocouple amplifiers are fed to channel-0 and channel-1 of
ADC of the microcontroller respectively.