Combining/paralleling wheatstone bridges

If you have, for example, a platform with 4 load cells, one on each corner, and you want indicated weight to be independent of load position, each load cell must be individually gain tweaked, so you wouldn't want to just slap them in parallel. I've seen "mixing" pots used here, but I'd imagine they would be a serious pain to adjust.

John

I worked in a scale shop for awhile, we used juntion boxes similar to these

And yes they do have pots to *balance* the cells. Rather common in truck scales. For truck scales to be certified legal for trade they need to pass a section test to prove the same readings regardless of the position of the vehicle on the scale. This is where *mixing the pots* is needed.

Unfortunately I never really bother to investigate the circuit design.

Chris

That is a common practice, we have hopper units that sit on three load cells, they are all tied together into one signal. with these cells, you simple zero each unit with the others not plugged in. when completed, we just plug them all in afterwards.

they are all joint together via a network at which point, should be balanced to a zero point. when ever any one of these units change it alters the balanced and if one cell is much more than the other. Basically, you get a very accurate reading with load shifting and so on because the three cells will differentiate the value.

We do have another set up where each cell is a DeviceNet link, these units are all combined via communications and talk to via an device number to read, calibrate, zero etc.. these work good for a single control process unit to indicate load imbalance if you wish to do so.