Hello,
I'm building a weight scale. Selected load cells are NA1, 40Kg (or 50Kg, yet to decide).
I've not yet selected the load cell amplifier, I'm thinking about the common HX711 or the ADS1231.
Recommended excitation voltage is between 5V and 12V, so both the two IC above will work.
The NA1 sensitivity is 2.0mV/V +-10%, find full specification below.
For my project it will be difficult to calibrate each cell, cause the weight is not equally balanced on that cells, it's some kind of "particular" weight scale.
I don't need that much accuracy. Let's say I need 100gr per cell accuracy.
Supposing to select the HX711 amplifier, a 40Kg cell (sensitivity is 2mV), set the gain at 128x and just keeping 14 bits out of the 24 to remove some noise (see note below), I should get 40000/(2^14*0.128*2) almost 10gr resolution, and that fits my need.
By datasheet rated output (sensitivity) and the other error involved (non-linearity and so on), should not affect the cell reading that much.
So my question is, can I skip calibration for each individual cell or am I missing something? I'm wondering if I can just set the conversion value between the raw IC output (let's suppose the HX711) according to the sensitivity of the cell, and keep this same value for all the difference cells.
Thanks!
Note about the HX711 there's an interesting noise analysis here:
https://forum.arduino.cc/t/hx711-noise-free-resolution-tests/351959