In the process of building my   Displacement Sensor  , I realized it could also make for a decent little load cell. And since I recently found myself wanting a better mass balance while trying to mix silicone, I decided to build one!

 

I have some work to do on the electronics side, but I'm pretty pleased with it! 

 

 

 

As the above calibration plot shows, the balance has a sensitivity of about 10 mV/g. From my brief testing thus far, it seems repeatable to about +/- 0.5 g.  With some work on the electronics, I think it's reasonable to think it could be improved by about an order of magnitude. In the simple config I have it in now (just a duplication and expansion of the circuit shown in the Displacement Sensor page), I think there are multiple sources of noise that could be improved on.

 

An issue that I'm less sure how to improve is that the mass of the tabletop itself eats up a fairly significant chunk of the total range.