MQ-303A

HANWEI ELETRONICS CO.,LTD MQ-303A http://www.hwsensor.com GAS SENSOR MQ-303A for ALCOHOL DETECTION * High sensitivity * Low power consumption * Miniature-size The MQ-303A is a tin dioxide semiconductor gas sensor which has a high sensitivity to alcohol with quick response speed. This model is suitable for alcohol detection such as portable breath alcohol checker or ignition locking system in automobiles. Structure Gas sensitive semiconductor material is a mini bead type and a heater coil and electrode wire are embedded in the element. The sensing element is installed in the metal housing which uses double stainless steel mesh (100 mesh) in the path of gas flow. The mesh is an anti-explosion feature (Fig 1). Operating conditions Fig 2 shows the standard operating circuit for this model. The change of the sensor resistance (RS) is obtained as the change of the output voltage across the fixed or variable resistor (RL). In order to obtain the best performance and specified characteristics, the values of the heater voltage (VH) circuit voltage (VC) and load resistance (RL) must be within the range of values given in the standard operating conditions shown in the Specification table on the next page. Generally, the sensor enters into normal working conditions after several minutes’ preheating, If you connect the sensor heater with a high voltage 2.2 ± 0.20V for 5-10 sec before normal testing , the sensor shall stabilize and enter into normal working conditions quickly. Sensit...