Data Sheet

MQ-3 Semiconductor Sensor for Alcohol
Sensitive material of MQ-3 gas sensor is SnO
2,
which with lower conductivity in clean air. When the
target alcohol gas exist, The sensor’s conductivity is more higher along with the gas concentration rising.
Please use simple electrocircuit, Convert change of conductivity to correspond output signal of gas
concentration.
MQ-3 gas sensor has high sensitity to Alcohol, and has good resistance to disturb of gasoline, smoke
and vapor. The sensor could be used to detect alcohol with different concentration, it is with low cost and
suitable for different application.
Character
Configuration
* Good sensitivity to alcohol gas
* Long life and low cost
* Simple drive circuit
Application
* Vehicel alcohol detector
* Portable alcohol detector
Technical
Data
Basic
test loop
The above is basic test circuit of the sensor.
The sensor need to be put 2 voltage,
heater voltage（VH） and test voltage（VC）.
VH used to supply certified working
temperature to the sensor, while VC used
to detect voltage (VRL) on load resistance
（RL）whom is in series with sensor. The
sensor has light polarity, Vc need DC
power. VC and VH could use same power
circuit with precondition to assure
performance of sensor. In order to make
the sensor with better performance,
suitable RL value is needed:
Power of Sensitivity body(Ps):
Ps=Vc
2
×Rs/(Rs+RL)
2
Model No. MQ-3
Sensor Type Semiconductor
Standard Encapsulation Bakelite (Black Bakelite)
Detection Gas Alcohol gas
Concentration 0.04-4mg/l alcohol
Loop Voltage V
c
≤24V DC
Heater Voltage V
H
5.0V±0.2V AC or DC
Circuit
Load
Resistance
R
L
Adjustable
Heater
Resistance
R
H
31Ω±3Ω（Room Tem.）
Heater
consumption
P
H
≤900mW
Sensing
Resistance
R
s
2KΩ-20KΩ(in 0.4mg/l alcohol )
Sensitivity S
Rs(in air)/Rs(0.4mg/L
Alcohol)≥5
Character
Slope α ≤0.6(R
300ppm
/R
100ppm
Alcohol)
Tem. Humidity
20℃±2℃；65%±5%RH
Standard test circuit
Vc:5.0V±0.1V；
V
H
: 5.0V±0.1V
Condition
Preheat time Over 48 hours
Vc
V
H
GND
R
L
V
RL