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WEBENCH® Tools: Soil EC on moving

Tool/software: WEBENCH® Design Tools

Hi,

I want to design circuit of Electical Conductivity which we used for Soil(While Moving on the filed of truck) measurement. In the Truck we need to connect has 4 electrode method

For 1st and 4th(last) has Need to provide the current and 2 and 3 electrodes need to measure potential voltage.

We are suing the battery of 12V..

Kindly provide the reference circuit for the same.

• Hello User,

Based on your information to me it seems like you are looking for instrumentation amplifier that can measure voltage across electrodes 2 and 3? Is that right ? If yes, please let me know and I can help you connect with the group that can help you with instrument amplifier selection.

Arjun

Applications, Current and Position Sensing

Hello,

Thank you for your replay. Yes we want to measure the volatge at electrode 2 and 3 points.

We are using the below method to calculate the electrical conductivity

The first and last electrodes we are injecting the current. so due to potential force electrode 2 and 3 will get the Volatge.

In this we want measure the current flowing through electrodes and volatge of elctrodes 2 and 3.

So can we measure this values by microcontroller ADC pins. We are giving the input of battery supply and that will giving the LM317 input and will doing the constant current of 50mA.

So kindly advice and provide the solution.

• In reply to Bala krishna Varkala:

Hello user,

Arjun

Applications, Current and Position Sensing

Hello Bala,

The following TI Application Note goes into detail on the various soil measurement techniques, and may be useful for your work.

Document Number: sbaa275
Title: A Basic Guide to RTD Measurements
www.ti.com/.../sbaa275.pdf

I believe your question has to do with how to use the LM317 as a current source.
Please clarify if this is not the case.

The LM317 datasheet shows an application where you can use this as a current source.
I've copied the circuit below.

Keep in mind that other current sources exist which may be options.
See the LM134/LM234/LM334 series of current sources.