Question on seed studio MQ9 gas sensor

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I am back to student life. This question is about coursework and in that I have to interface a Grove MQ9 Gas sensor 1.4. Here is the link of it

 

http://wiki.seeed.cc/Grove-Gas_S...

 

In simplest terms, just accept analog signal into arduino and use it as a measure of gas concentration.

 

The datasheet of sensor describes the heater voltage of 5 volts for 60 seconds and then 1.4 volts for 90 seconds.

 

The module mentioned above, has four terminals, namely VCC, SIG, NC and GND. SIG is measured signal output, while VCC is tied to 5 volts. Seed studio has given interface code but does not mention anything about the heater voltage cycles? I am a bit lost, whether the sensor module has inbuilt circuit to perform 5v/1.4 volts cycle, I am not sure. Any comments on this are welcomed.

 

I was confused whether this is arduino question or general electronics, I thought it is general electronics and hence here.

Many thanks in advance

This topic has a solution.
Last Edited: Sun. Dec 10, 2017 - 11:38 AM
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thakkarhimanshu wrote:
I was confused whether this is arduino question or general electronics,

Actually, it's neither - it is a specific question about a particular product.

 

As such, you should b directing the question to the manufacturer and/or supplier.

 

Or, as this has been given to you as part of a school assignment, you should ask your teacher for the complete documentation.

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I did write an email to the supplier but email to their technical support did not deliver.

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It is my interpretation of the datasheet that you run the heater at 5V for best sensitivity.
The specifications you quoted are for the heat up time - ie the time it takes from applying the power until the sensor is warmed up sufficiently to give accurate readings.

Last Edited: Sat. Dec 9, 2017 - 10:06 PM
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Thanks Kartman for spending your valuable time looking into the matter.

 

I had not been thinking in right direction but you have shown me that. When looking into the sensitivity, the heating element has higher sensitivity to LPG or CH4 when 5 volts are applied. Whereas, during 1.4 volts cycle, the sensitivity is higher for Carbon Monoxide.

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You could use a lm317 and use a port pin to switch resistors to switch the voltage.