Gesamt 2 Seiten
HANWEI ELETRONICS CO.,LTD
GAS SENSOR MQ-303A for ALCOHOL DETECTION
* High sensitivity
* Low power consumption
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.
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 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.
Fig 3 shows the sensitivity characteristics curves of the MQ-303A (typical data). Sensitivity characteristics of the
gas sensors are expressed by the relationship between the sensor resistance and gas
concentration. The sensor resistance decreases with an increase of gas
concentration based on a logarithmic function.
TEL: 86-371-67169070 67169080
E-mail: [email protected]
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|[ MQ-303A Schematic.PDF ]
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