You probably have some way to go before you hit my tallyGeez, i can't believe i messed up the layout again!
This is great. I started to watch the video and spotted one thing straight away though. The pot doesn't seem to be connected at all.Got one more INA122 and figured i'd hook it up to a breadboard before soldering everything together
You seem to have already figured out the direction of the tracks in the breadboard as you have connected up the pins of the INA122 using them, but I think you got them mixed up when you installed the pot as you have both the wires to the right of the pot on the same track and the pot has all it's pins on one track too.
Will have to do this one tomorrow with some more tools.2. find a way to mechanically clamp one side of the bar load cell so that you can apply a reasonable amount of force to it. If you have something like a luggage scale, try using that on the other end so you can verify you are able to apply > 10kg
I believe this is as you mentioned before, pin 6 goes to A0 on Arduino.1. can you take a photo of the breadboard showing the markings on the chip clearly so we can verify your wiring
Not sure about the bridging :/EDIT: also, when you swapped the cells in the vid, I could not tell if you had the 1K resistors making up the other half of the bridge.
First of all, the wiring on the Arduino side is without ambiguity: Pin 7 goes to VCC, pin 6 goes to A0 (or any other analog pin on the arduino), and pins 4 and 5 go to GND (you could also connect pin 5 to VCC if you want to invert the output, but lets keep it simple for now). No need to switch the wires around on that side.
Some things I can tell from the pictures you provided:
But as GeekyDeaks suggested, let's focus on getting the 4-wire load cell working first.
- The orientation of the INA122 looks ok to me and the pin numbering should be correct.
- In the second picture, you have connected the black wire of the load cell to pin 1. That wire should be connected to either GND or VCC. I think you had it right in your video.
- The wiring diagram in the last picture can't be correct. Assuming the color coding of your load cell is the same as mine (red=signal, black/white = GND/VCC), then the resistors are correct, but the white and red wire to the board should be swapped (this is really confusing, as for the 4-wire load cells, red actually is the VCC and not the signal wire). Also note, that the used resistors should be matched as closely as possible, preferably from the same production batch.
I would recommend to always use the black wire on the load cell as GND to avoid further confusion (as the load cells themselves don't have polarity, you could also connect it to VCC). Then, for the 4-wire cell, connect the red wire to VCC. The two signal wires (white/green) go to pins 2 nad 3 of the INA122, here you might have to switch around to find the right configuration.
With the 4 wire cell wired up as suggested the voltage readings look more like the approximations, GeekyDeaks mentioned before, except for when the white loadcell wire is connected to pin 3 or 2.
The reading on pin 3 and 4 is a bit low = +- 1.4V
Sorry, have been busy with work and only just got around to looking at this. I agree with @Panicpete, this seems odd and you should verify the resistances in the loadcell between the wires to determine it's internal configuration.The reading on pin 3 and 4 is a bit low = +- 1.4V