605-00007 Parallax Inc, 605-00007 Datasheet - Page 3

• Manufacturer Part Number: 605-00007
• Description: Flow Sensors CO Gas Sensor
• Manufacturer: Parallax Inc

Specifications of 605-00007

• Supply Voltage: 5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Signal
VH5v
1.4v
HANWEI ELECTRONICS CO ., LTD
OPERATION PRINCIPLE
. The surface resistance of the sensor Rs is obtained through effected voltage signal output of the
load resistance RL which series-wound. The relationship between them is described:
Fig. 5 shows alterable situation of RL signal output measured by using Fig. 2 circuit output
signal when the sensor is shifted from clean air to carbon monoxide (CO) , output signal
measurement is made within one or two complete heating period (2.5 minute from high voltage
to low voltage ).
excellent long term stability. Its service life can reach 5 years under using condition.
SENSITVITY ADJUSTMENT
using this components, sensitivity adjustment is very necessary. we recommend that you calibrate the
detector for 200ppm CO in air and use value of Load resistance that( R
considering the temperature and humidity influence. The sensitivity adjusting program:
-10
TEL:[phone] 67169080
Sensitive layer of MQ-7 gas sensitive components is made of SnO
When accurately measuring, the proper alarm point for the gas detector should be determined after
a. Connect the sensor to the application circuit.
b. Turn on the power, keep preheating through electricity over 48 hours.
c. Adjust the load resistance RL until you get a signal value which is respond to a certain
d. Adjust the another load resistance RL until you get a signal value which is respond to a CO
Resistance value of MQ-7 is difference to various kinds and various concentration gases. So, When
carbon monoxide concentration at the end point of 90 seconds.
concentration at the end point of 60 seconds .
1.5
1.4
1.3
1.2
1.1
0.9
0.8
0.7
0.6
0.5
1
0
60s
90s
Supplying special IC solutions, More detailed technical information, please contact us.
In air
10
MQ-7
Rs\RL = (Vc-VRL) / VRL
20
In 100ppmCO
30
FAX:[phone]
Fig.5
33%RH
85%RH
MQ –7
40
Fig.4
50
Temp
Fig.4 is shows the typical
dependence of the MQ-7 on
temperature and humidity.
Ro: sensor resistance at 100ppm CO in
air at 33%RH and 20degree.
Rs: sensor resistance at 100ppm CO at
different temperatures and humidities.
In air
L
) about 10 KΩ(5KΩ to 47 KΩ).
2
Email: [e-mail]
with stability, So, it has
http://www.hwsensor.com