Electrical Conductivity and PH design circuit

Dharmesh Joshi

Expert 1925 points

Other Parts Discussed in Thread: LMP91200, TIDA-00561

Dear All

Is there any reference design or application note on how to create the circuit for a EC and PH probe circuit for liquid substances?

Or if someone can point me in the right direction.

Thanks

Regards

over 9 years ago

0 Victor Salomon over 9 years ago

TI__Expert 3910 points

Hello Dharmesh,

LMP91200 is an Integrated analog front end for pH Sensing Applications and we have a reference design that uses this part, TIDA-00561, which you can find in the following link:

0 Dharmesh Joshi over 9 years ago in reply to Victor Salomon

Expert 1925 points

Thank You
How would i develop a electrical conductivity meter with this IC or any other?

0 Victor Salomon over 9 years ago in reply to Dharmesh Joshi

TI__Expert 3910 points

Dharmesh,

There is a couple of approaches used in Electrical Conductivity depending on your application. If you are considering Inductive Sensing check out the products available and for any Inductive Sensing specific questions please go to the Inductive Sensing Forum.

If you are using electrode conductivity sensors you will need to work on your signal conditioning, refer to the following E2E Post for reference:

0 Dharmesh Joshi over 9 years ago in reply to Victor Salomon

Expert 1925 points

Dear Victor
Thank You for your reply
Yes i would like to use this for testing in solution as well as soil samples. Could this be achieved with inductive sensing?

I will also read that post that you recommended.

Thank You

0 Dharmesh Joshi over 9 years ago in reply to Victor Salomon

Expert 1925 points

Dear Victor

I had a look

Can you please explain what you mean by signal conditioning? Would this mean by signal output such as sine wave?

I am thinking using the PWM output of my microcontroller. I am not sure how this would be incorporated as an AC signal, with 3.3V

As suggested to use an transimpedance amplifier, which is first schematic, but is the second schematic is total different design?

Where would probes connect?

Would you have any document on this?

0 Victor Salomon over 9 years ago in reply to Dharmesh Joshi

TI__Expert 3910 points

Dharmesh,

I hope I can address some of your questions for for more specifics I would recommend posting on the forum of the technology you are considering (e.g. Inductive Sensing Forum or Precision Amplifiers Forum).

Dharmesh Joshi said:
Can you please explain what you mean by signal conditioning? Would this mean by signal output such as sine wave?

What I mean is the circuit you would design to condition the signal to be appropriate for the input of our ADC, such are the two examples on the post I shared.

Dharmesh Joshi said:
I am thinking using the PWM output of my microcontroller. I am not sure how this would be incorporated as an AC signal, with 3.3V... As suggested to use an transimpedance amplifier, which is first schematic, but is the second schematic is total different design?

I am not too familiar with Conductivity Probes, but from I can gather you measure the current given the change in conductivity, for any further questions on this post on the Precision Amplifiers Forum.

Dharmesh Joshi said:
Where would probes connect? Would you have any document on this?

We do have application specific documentation (see: ti.com/applications), however, we do not have a specific page for 'Conductivity Probes', but we do have a more general page for 'Process Analytics'.

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Electrical Conductivity and PH design circuit