I'm trying to use the Sparkfun OpenScale (schematic) in combination with this loadcell (datasheet) and am having some strange issues. Not only is the signal inaccurate and inherently noisier than it should be, but it also seems to be sensitive to my proximity to it. I.e. the mean of the readings will be completely and repeatably different depending on whether or not I am near the Openscale board; see below:
I've calibrated/tared the openscale according to the provided guide. I've also observed the same results with an identical loadcell. I know the openscale board is working because I was able to get everything working fine with a TAL220 load cell on the same board. Some other things I've tried:
isolating from my phone/smart watch/any nearby electronics save for the computer it's plugged into
coiling load cell cable in a ferrite choke
applying ferrite choke on USB cable]
wrapping cable in tin foil tied to Openscale shield terminal
using both amplified and unamplified terminals on the Openscale
I don't have many other options in loadcells that will work for my application so I'm pressed to figure out what is going on here. Any ideas?
I see the problem on the schematic oops I do not see the schematic. Also missing is wiring and grounding information. Links to technical information on each of the hardware devices will also help.
Have you checked the loadcell with a meter to verify its intact? Its a bridge of 4 resistances and you should be able to check each resistance is present by checking they all read the same.
The symptoms suggest a floating input or something basic is wrong with the physical circuit.
Sorry about that. I included schematics for the load cells but if you are talking about the schematics for the openscale specifically, I updated the OP with a link to it. But it probably does bear mentioning that the loadcell I am having issues with has a different color scheme from what I've seen around, but as far as I can tell I have it hooked up correctly. See below for how I have it hooked up:
No, the FC2311 isn't shielded. The datasheet for the TAL220 that I was able to get working says it is shielded but does not appear to be either (only 4 individual wires)
I tried measuring with an oscilloscope but didn't see anything meaningful. Could have been doing something wrong though. Could you elaborate on what might be oscillating?
Here is what I measured; refer to the "FC2311/Openscale Wiring" drop down or the FC2311 schematic in the OP.
Not sure what the other choice you intended was, but I do have the FC2311. FC2311-0000-0500-L, to be exact. Edit: sorry, I read your two P/N's as the same thing
