DEVELOPMENT OF A MICROCONTROLLER BASED GREENHOUSE GAS DETECTOR: CO2 AND CO

Abstract

The development of CO2 and CO gas detecting system which is portable, cheap and easy to implement is presented. This detector is made up of dual power supply (AC and DC), sensing circuit, microcontroller unit and liquid crystal display effectively coupled together for efficient performance. To detect CO2 and CO gases, metal oxide sensors (MQ 135 and MQ 7) are used. When these gases come in contact with the sensing element, it lowers its electrical resistance. The PIC18F2550 microcontroller is used for this portable gas detector. The developed instrument was calibrated against a Kane Gas Analyser. It measures carbondioxide and carbonmonoxide concentration in air, within the range of 10 to 2000 ppm and with a resolution of 1 ppm. It is found that the gas concentration indicated by the developed system is a linear function of CO2 and CO in the test chamber and the output is in good agreement with the actual gas concentration. This indicates that the developed system works relatively well with great accuracy and reliability