Sensor amplifier circuit diagram

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vasia_uvi

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Sensor amplifier

Hi!
I have a gas sensor from
h**p://www.gaskiki.com/ns/product/p1.htm
and i need to comand with this a relay.
When is sensing gas the relay must be closed.This circuit is good?How this circuit works?
I have never understood the OPAMPS
 

Re: Sensor amplifier

To drive a relay, you need to add 2 things to your circuit:
1. Comparator, which will detect when the output signal (proportional to gas level) will reach the threshold, where you want to close the relay. Almost any comparator (e.g. LM393) as awell as opmap wired as somparator will work for you.
2. MOSFET, whose gate is connected to the output of the comparator.

May be the circuit below can work for you.
 

Re: Sensor amplifier

Thanks for reply!
I have an other question: what the first Opamp do(pin 1,8,4,2,3) and the second Opamp?
The gas sensor is modifying his resistance(Ohm) when the methan is in the chamber.
 

Re: Sensor amplifier

I have made the circuit and is working just fine.....without any extra components.
 

Re: Sensor amplifier

I have an other question: what the first Opamp do(pin 1,8,4,2,3) and the second Opamp?
Click to expand...
in short, the 1st OP is an inverting amplifer + Low pass filter
and the 2nd OP is acted as a comparator with hysterisis
 

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