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CN-0349

Question asked by bwjm on Nov 20, 2016
Latest reply on Dec 2, 2016 by R.L

Hi there,

 

I am using CN-0349 development board to measure EC. I have these setting

Rcal1 = 100ohms

Rcal2 = 1K ohms

Rfb = 100

 

Vp-p = 2v

Output external Freq = 2Khz

MCLK=1MHz

Frequency Increment = 0

Number of increment = 1

 

I have 2 questions that need help on.

 

1) My graph mS vs magnitude is inverted

Rcal = 1000ohms, real number=805, Imaginary number= 64978, magnitude = 64982

Rcal = 100ohms, real number=7762, Imaginary number= 60185, magnitude = 60185

Is this wrong?

 

2) If i would wish to measure high conductance, how can i measure below 100ohm. The circuit has a R2=100ohm in series with the unknown conductance. So if my unknown conductance is 0ohm, i would still measure 100ohm.

The table shown in CN-0349, shows the measure can be done at 10ohm. How can it be?

Thank you

 

Regards

Bryan

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