I have a 3-wire load sensor that looks like this:
I'm trying to wire it up to my Arduino to detect changes in weight. From what I understand, the changes in voltage are so small that the Arduino can't detect the changes without amplifying the voltage. So I bought an 8-pin LM741CN Op-Amp at Radio Shack that looks something this:
I found this video that shows how to wire everything up. However, I can't figure out the schematic and why they are using two load sensors instead of just one. They also mention resistors but I'm not sure why they are using them (and why the sizes they chose), or where in the circuit to put them.
Can someone please help me figure out how to wire this thing up to detect changes in voltage? Also, is there a way to do this by using only one of these sensors? This is what I've done so far:
The amp also has some pins that I don't understand: Offset null, NC. What are these pins for? Should I be using them?
Update: Now I am working with an Instrumentation Amplifier (AD623). I also now have a 4-wire load sensor that I am playing with. Still can't get it to work, but I thought I would try to understand that before moving to the 3-wire load sensor.
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