Interfacing Gas sensor with 3.3V ucontrollers

[shubh1994]

I am trying to interface MQ7 (CO) with TI Stellaris launchpad (operating voltage is 3.3V) but according to datasheet MQ7 requires Vh= 5v
and Vl=1.4v.
So, how to interface MQ gas sensors with 3.3v microcontroller????

 

[jayanth.devarayanadurga]

Voltage level translator made using 2 transistors.

 

[shubh1994]

Is it not possible to use this MQ7 (gas sensor) with 3.3ucontroller directly without using level shifter??
Can't we heat the heating element will 3.3V??

 

[jayanth.devarayanadurga]

It might work. See this circuit. **broken link removed**

It is for 5V. Just change the resistors connected to LEDs to 180E if you use 3.3V. Op Amp is used as a Comparator. Use Op Amp like OPA350 or any other op amp which works from 2.5V to 5V.


Here is a level sensor circuit but level sensor is of no use for your purpose.

https://www.incrediblediy.com/2013/02/simple-33v5v-level-shifter.html