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Conductivity Circuit

Former Member

Wondering if anyone can help.

Need to design conductivity circuit to interface with standard sensor to measure in NaCl solution.

Sensor has PT100 temperature sensor (for compensation) and plate electrodes need to drive with AC stop liquid polarisation current flow proportional to conductivity mS.

Will interface to PIC for logging.

Can use AC bridge measurement. Had though use LVDT drive circuit AD do one expensive.

Any thoughts.

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    There was a blog on a salt detector on Hackaday a few month ago.  It used an RC circuit to measure the resistance between clean water and salt baring water.  As I recall, the circuit used an LM324 operational amplifier with various levels of gain.  Once you calibrate it to zero out with pure water, you can then measure various levels of salt in the water by the RC time constant change.

     

    Hope this helps.

    DAB

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  • 0

    There was a blog on a salt detector on Hackaday a few month ago.  It used an RC circuit to measure the resistance between clean water and salt baring water.  As I recall, the circuit used an LM324 operational amplifier with various levels of gain.  Once you calibrate it to zero out with pure water, you can then measure various levels of salt in the water by the RC time constant change.

     

    Hope this helps.

    DAB

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