Differential mode ADC - wrong readings

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JaRa_1183061
Level 2
Level 2
10 replies posted 10 sign-ins 5 replies posted

Hi

I am using the ADC_DelSig in differential mode. I am interested in sampling the voltage between two metal electrodes in electrolysis (between 100 mV to 1 V). The ADC voltage is fluctuating a lot – most of the time giving random values.  My question is therefore, what could be wrong?

Here is my setup for the ADC.

JaRa_1183061_0-1633874356548.png

 

JaRa_1183061_1-1633874356553.png

Pin_1 is on metal 1 (positive) and pin_2 is on metal 2 (negative). I am using the ADC_DelSig_1_CountsTo_mVolts(ADC_DelSig_1_GetResult32()) function.

Thanks - 

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1 Solution
Len_CONSULTRON
Level 9
Level 9
Beta tester 500 solutions authored 1000 replies posted

JaRa,

As Vasanth suggested, it is always useful when testing out your design to apply a known voltage on the electrodes.  This will allow you to verify the quality of your design before using it on a unknown test environment ( ie: electrolysis bath.)

Using a series of "known" voltages is also a good method of calibrating your system before putting it into use.

 

Len
"Engineering is an Art. The Art of Compromise."

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2 Replies
Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

Hi, 

One doubt, are the absolute voltages on the terminals are within the working range of the device ?(between VDDA and VSSA ?) Is the setup working properly if you try to measure any other known voltage?

Best Regards,
Vasanth

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Len_CONSULTRON
Level 9
Level 9
Beta tester 500 solutions authored 1000 replies posted

JaRa,

As Vasanth suggested, it is always useful when testing out your design to apply a known voltage on the electrodes.  This will allow you to verify the quality of your design before using it on a unknown test environment ( ie: electrolysis bath.)

Using a series of "known" voltages is also a good method of calibrating your system before putting it into use.

 

Len
"Engineering is an Art. The Art of Compromise."
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