HX711/Load Cell Temperature Sensitivity

Hi All,

I’m wondering whether anyone’s seen the output of an HX711 load cell amp become VERY temperature dependent below a certain temperature.

I’ve got a set of hacked bathroom scales with the 4 strain gauges connected to the HX711 via a Wheatstone bridge. As you can see in the attachment, everything looks good indoors at around 22 DgC (where it was from around 07:00 on the graph). When it was outside the night before it was behaving much more erratically. I’ve now seen the same behavior with the Arduino connected to a breadboard and PCB, powered via USB and 5V supply to the 5V pin, different HX711s etc.

The only common factor is the scales, and since they are working at some temperatures my best guess is that one of the strain gauges is a bit dodgy - anything fundamentally wrong with my wiring or code isn’t likely to cause these symptoms

Has anyone seen anything like that before? If it’s a common problem, then a different set of scales is unlikely to help!

Cheers

Rich

Read this PDF:Known load cell problems

Paul