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Usable for 10 resistors


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5 replies to this topic

#1 AndreB

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Posted 31 May 2013 - 12:19 PM

Hi, we need to install 10 strain gages on a wing profile to evaluate strain at specific locations. We currently use a Lab Jack U12 for load cell (12K ohm) mounted on a hydraulic jack to load the test wing which work perfectly but takes already some channels. So, can we set-up the LabJack for these resistors to to have reading of 10 output voltages separately, simultaneously or sequencially (I read on the forum that for USB it have to be sequencial...)? Furthermore, a wheatstone bridge is used with these resistors. :mellow:

#2 LabJack Support

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Posted 31 May 2013 - 12:37 PM

To measure from a bridge circuit with the U12, you need to provide excitation for the bridge and you need an instrumentation amplifier. So what are you using for excitation and amplification?

https://forums.labja...?showtopic=4376

#3 AndreB

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Posted 31 May 2013 - 12:54 PM

To measure from a bridge circuit with the U12, you need to provide excitation for the bridge and you need an instrumentation amplifier. So what are you using for excitation and amplification?

https://forums.labja...?showtopic=4376

We used a 6 V battery and a Labjack EI-1040 Dual Instrument Amplifier.

#4 LabJack Support

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Posted 31 May 2013 - 02:58 PM

How fast do you need to scan the 10 bridge signals? What are you using for software?

#5 AndreB

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Posted 03 June 2013 - 05:58 AM

How fast do you need to scan the 10 bridge signals?

What are you using for software?


The speed does not really matter. we can wait every load level until the 10 resistors have been measured so we can have an idea about the strains for the whole wing at one particular time. Do you think that connecting 10 gages at a time on the U12 is feasible?

For the software, we use the LJstream V1.05 and VersaPro! I will look further for more details.

#6 LabJack Support

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Posted 03 June 2013 - 10:09 AM

Doing things similar to now, you would need 5 EI-1040s and 2 U12s to read 10 bridge circuits.

You then need software to read 6 inputs on 1 U12 and 4 inputs on the other U12. You can write your own program in about any language, or use DAQFactory:

http://labjack.com/s...rt/u12/examples

http://labjack.com/s...ions/daqfactory


An alternate route, would be 1 U3-LV, 1 CB15, and 5 LJTick-InAmps. You could then use LJLogUD to collect the 10 channels of data.


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