01-18-2017 10:51 AM
I want to use the PXIe-4331 to measure the changes (very small) in voltage of one resistor. I want to use the built-in excitation source (2.5 V) to excite a wheatestone bridge (non standard); the wheatestone bridge will be balance via a potentiometer.
Once the bridge is balanced, I want to monitor the changes of the output of the bridge. Is it possible to configure the card for working as I am describing? The bridge is going to look like a "quarter bridge" configuration (3 resistors are constant, and 1 is going to fluctuate), but the resistances are going to have non-standard values. I just want to understand the changes of the output, so I can correlate them to resistance. Best regards and many thanks in advance.
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01-18-2017 10:54 AM
Hello,
I want to use the PXIe-4331 to measure the changes (very small) of one resistor (it is an strange material which change its resistance in a random way; I want to monitor the changes to understand why this is happening). I want to use the built-in excitation source (2.5 V) to excite a wheatestone bridge (non standard); the wheatestone bridge will be balance via a potentiometer.
Once the bridge is balanced, I want to monitor the changes of the output of the bridge. Is it possible to configure the card for working as I am describing? The bridge is going to look like a "quarter bridge" configuration (3 resistors are constant, and 1 is going to fluctuate), but the resistances are going to have non-standard values. I just want to understand the changes of the output, so I can correlate them to resistance. Best regards and many thanks in advance.
01-18-2017 10:56 AM
Hello,
I want to use the PXIe-4331 to measure the changes (very small) of one resistor (it is an strange material which change its resistance in a random way; I want to monitor the changes to understand why this is happening). I want to use the built-in excitation source (2.5 V) to excite a wheatestone bridge (non standard); the wheatestone bridge will be balance via a potentiometer.
Once the bridge is balanced, I want to monitor the changes of the output of the bridge. Is it possible to configure the card for working as I am describing? The bridge is going to look like a "quarter bridge" configuration (3 resistors are constant, and 1 is going to fluctuate), but the resistances are going to have non-standard values. I just want to understand the changes of the output, so I can correlate them to resistance. Best regards and many thanks in advance.
01-18-2017 11:18 AM - edited 01-18-2017 11:20 AM
01-20-2017 09:41 AM
If you have non-standard values for the resistances, it is not clear how you would use the internal bridge completion circuits of the PXIe-4331. It appears that the full bridge configuration (which requires you to supply all the fixed resistors and the potentiometer) may be the better choice. Look at Chapter 2 of the User Manual.
The specifications are in terms of mV/V so you may need to do some calcualtions to get the actual resistances.
Lynn
01-23-2017 02:12 AM
Hello, Lynn
Many thanks for your help. I am trying to use it as you are explaining:
1- Creating my own balanced wheatestone bridge
2- Using the internal stabilised excitation voltage of the card
3- Reading the output of the bridge (mV/V), and by multiplying by the excitation voltage get the mV.
4- Having 3 known resistor, work out the value of the fourth one.
Best regards and many thanks again.