Gas detector project

Chazziemann

Hi,

Starting a small project, building a gas detector using a electrochemical senor. Anyone have any info on a simple circuit design ?

Thanks

DublinDilbert

Chazziemann wrote: »

Hi,

Starting a small project, building a gas detector using a electrochemical senor. Anyone have any info on a simple circuit design ?

Thanks

You circuit will depend on the type of sensor and on what sort of Gas your trying to detect

NoseyMike2010

And can also depend on what type of Zone you would plan to have your gas detector!

There are three zones..... hopefully somebody can expand on this to clarify things!!!!

The different zones would depend on what type of items you can and can't use. If your detecting gas you don't want electronics that could spark!

FarmerGreen

A non intrisically safe gas detector.
Sounds like fun, at least you would know when you had a problem.
Soonish.

pljudge321

NoseyMike2010 wrote: »

And can also depend on what type of Zone you would plan to have your gas detector!

There are three zones..... hopefully somebody can expand on this to clarify things!!!!

The different zones would depend on what type of items you can and can't use. If your detecting gas you don't want electronics that could spark!

Mmm Atex Regulations. Spent a happy summer doing that

Chazziemann

I will be using a electrochemical sensor, current is proportional to concentration.

Could i just connect the sensor to a multimeter and see if i get a reading or do i need other components??

gooch2k9

What do you want it do if you do detect gas? Siren?

Chazziemann

First stage: If the sensor detected gas, current will flow from the sensor. This current will pass through a relay which will switch on a second stage.

How would you build the circuit for the first stage

FarmerGreen

If you would just give us a link to the sensor data sheet that would be great.
The first stage would be to convert the sensor output to a voltage proportional to the gas concentration.
The second stage would be to compare the voltage to a 'setpoint'
and operate a relay if it goes above this.

DublinDilbert

Chazziemann wrote: »

I will be using a electrochemical sensor, current is proportional to concentration.

Could i just connect the sensor to a multimeter and see if i get a reading or do i need other components??

You'll have to look at the data sheet for the sensing element you select, but typically the current is very small so will need to be amplified. A few stages of amplification may be required.

I might be useful to get a few off the shelf detectors and take them apart to see what way they are designed.

Chazziemann

Here is the sensor data,

Any ideas on an op amp to operate a relay? and what relay

I was looking at a few different amps like the LM741 or the OPA347 but when it come down to the finer details i get lost.

As for relays i was looking at the Solid state SPSTNO types but again i am getting lost in the finer specs

Any advice will be great

DublinDilbert

There really isn't enough information in that datasheet. Get the full datasheet off them, you could also email them and ask for application circuit examples.

Don't touch a 741 opamp, use something like a LM2902 or LM2904, they will operate off a single rail and can also function as comparators, which you'll probably need in this case.

FarmerGreen

From a different manufacturer admittedly
Sensor spec http://www.alphasense.com/pdf/H2SB1.pdf

Application note describing how to use it http://www.alphasense.com/pdf/AAN_105-03.pdf

Chazziemann

thanks for the info, much app...