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[on:]

Hey guys,

My background is in programming so am something of a newbie when it comes to analogue devices. I have taken apart a cheap set of digital bathroom scales and removed the sensors from each of the foot cups. I'm fairly sure it's a type of strain guage but I could be wrong. All I need to know is how to hook it up my Arduino board so I can get a reading on the force being applied. I've found a number of circuit diagrams for strain guages but they all have 4 wires coming out the strain guage where as mine only has 3: 1 red (presuably V+), 1 blue (presumably ground) and 1 white (presumably signal out). I suspect there should be an op-amp involved somewhere and I have a bunch of LM324n's lying around (as you do) but I'm pretty much flying blind. Any guidance would be appreciated.

The sensor looks like this

[Reply #1 on:]

Do you have some pictures of the other side of those 3 wires ?

Red/blue could be pos/neg, knowing what they were attached to (often edit) makes it  a lot easier.

[Reply #2 on:]

Not sure how much use it'll be but here they are. The first photo shows where the wires lead into a small mounted board. There are four sensors connected to this board although some of the wires have fallen out so only 2 sensors are still full connected. This mounted board then connects through to the other side of main board (top right on second photo) where it then goes through various resistors and into what appears to be an small op-amp (L24C02B), which can be seen in the second photo.