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I have these 2 strain gauges as you can see in the image (code 632-180) and I want to connect it to the Arduino so I can read the deformation.

They should be in Wheatstone Half Bridge.

I read that I would have to connect it to an operational amplifier so i can be able to read the data, so i have already an INA122P from TI and a LM234 DRG3 is coming.

Hope someone can help me with the connections from the strain gauge to the amplifier and then to the Arduino.

Thanks in advance.

enter image description here

enter image description here

so guys, I've tried to make a schematic with the help of the datasheet of INA122p and i hope you can now help me.

here is a image of the datasheet of an example in wheatstone full bridge. https://i.sstatic.net/krOFi.jpg

here is what i will try to do with the half bridge. https://i.sstatic.net/2PrFH.jpg

Is it correct?

Hope you can help me.

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    \$\begingroup\$ Where is your schematic? \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Jun 16, 2015 at 15:36
  • \$\begingroup\$ that is what i'm looking for \$\endgroup\$
    – Carlos Maia Neto
    Commented Jun 16, 2015 at 15:38
  • \$\begingroup\$ A bit of the "protocol" for school work (I assume this is school work) and most other questions: is that SE.EE users like to see what you've tried and where you fail at. In this case, you are looking for a schematic so SE.EE would prefer to see what schematic have you made. It's much easier to point out where you went wrong, than explaining in great detail everything that you need to do, in order to accomplish your goal. \$\endgroup\$
    – Nick Williams
    Commented Jun 16, 2015 at 15:48
  • \$\begingroup\$ imgur.com/rwkE35c this is what I've managed to do so far. \$\endgroup\$
    – Carlos Maia Neto
    Commented Jun 16, 2015 at 16:02
  • \$\begingroup\$ I suggest you read the op amp datasheet, there often are example schematics. The arduino probably has an ADC inside of it, use that. Read the datasheet. \$\endgroup\$
    – Formagella
    Commented Jun 16, 2015 at 21:36

1 Answer 1

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i do not know whether this answer is in time. If not just ignore it! the two strain gauges are shown separated. that means if one is bent the other is perhaps not bent. generally at least wto strain gauges are used in any sensor, so that their temp coefficients can cancel each other, by utilising them in a nridge or call it half bridge. When they arer separate as shown, this advantage may cease to exist. are you jts trying to get to see their resistance variation? A 4 1/2 digit meter in the range slightly exceeding the resistance of the strain gaugse cna be used to get a feel of what this modifgied resistance is after bending. In such a cse, two may not be reuired. If two are used, plan to use it as half brigde. One in upper part and another in lower part of wheatsotones bridge, with the other two being say 1% low ppm resistors of 1k or 470 ohms.

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