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Let me preface this by saying I'm a total beginner to this. My area is Software, not usually electronics; and I haven't done any since I was in high school.

I've done a lot of reading about Wheatstone bridges in preparation for this, but I'm struggling to apply the diagrams to what I have in front of me.

I'm trying to follow this tutorial. In terms of the code side of it, I'm totally fine with what it does, how it calibrates the readings etc. My main problem is the actual scales part of it.

I have the I/O shield that they use in the example as well.

My main problem is the scales. I have a set of scales with 4 load cells in each corner. I have no idea where to start with wiring this up. I desoldered the cables from the board, which also handled the power supply, as I figured I would need to rewire a lot of it.

The tutorial itself isn't very clear as it refers to a certain scale, which I can't get in the UK.

Each load cell has 3 cables coming from it: a red, black and white.

Close up of one corner

My basic questions:

  1. How would I go about wiring this into a Wheatstone Bridge?
  2. Where would I then connect the battery back to the cables?
  3. How can I determine what the individual cables actually do?

If I need to provide any more information, I'll do my best to reply with what you need. Thank you in advance

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    \$\begingroup\$ Dismantling it further until you find a part number, then look up the datasheet: that ought to give you (3). \$\endgroup\$ – pjc50 Oct 19 '15 at 13:28
  • \$\begingroup\$ I've had another look at the board. Each cell seems to be grouped into V-, E+, V+ and E-, with each cable taking a position within those groups \$\endgroup\$ – jmo Oct 19 '15 at 13:31
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Start with this concept: -

enter image description here

And take your three terminal load cells and fit them at each corner of the diamond like so but note that the labels for input power (+) is in the wrong place unfortunately - basically excitation voltage should be applied across opposite corners and output taken across the two opposite corners remaining: -

enter image description here

Circuit wise it looks like this: -

enter image description here

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  • \$\begingroup\$ I assume the "signal+/-" refers to E+/- on the original board? \$\endgroup\$ – jmo Oct 19 '15 at 13:47
  • \$\begingroup\$ I have no idea what your original board is but "E" would imply "excitation" to me corresponding to the DC symbol on my final picture. \$\endgroup\$ – Andy aka Oct 19 '15 at 13:54
  • \$\begingroup\$ Ah, OK. This is very helpful, thank you. I'll give it a go and see what happens! \$\endgroup\$ – jmo Oct 19 '15 at 13:55
  • \$\begingroup\$ I've made an amendment in a note about the 2nd circuit - it has labels in the wrong place. \$\endgroup\$ – Andy aka Oct 19 '15 at 13:57

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