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Precision Load Cell (Wheatstone Bridge) Simulator

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Overspeed:
Hello

Thanks for explanation I agree but

a strain gage is a not a rubber band , a strain gage have a gage factor so resistance variation is limited and limited also by the fixation / gluing so a simulator will match the reality no need of a wide resistance variation but better to have an very accurate link between Delta resistance and output voltage of the bridge

AC bridge request ( or have in the past as HBM AC bridge ) complex electronic with some advantages but I use DC since years that work easy

I link a interesting doc on 1/4 bridge and a symmetrical dual op amp circuit

I agree on the output voltage to voltage ref ratio solution

Regards
OS

hozone:
Thanks again.
The DAC, or any other active component would work better for this design.
I think I'll go for a +-0.003% VExc absolute error label for this passive simulator. Even if it's a unknown behavior to me  :palm:

Overspeed:

--- Quote from: hozone on August 06, 2024, 07:54:27 am ---Thanks again.
The DAC, or any other active component would work better for this design.
I think I'll go for a +-0.003% VExc absolute error label for this passive simulator. Even if it's a unknown behavior to me  :palm:

--- End quote ---

Hello

Can you provide the calculation : I'll go for a +-0.003% VExc absolute error label

That interesting

Regards
OS

hozone:
Hi @Overspeed,

Don't know if I'm right, and why it's like so, but:

Excitation 10.024V readings (expected, read and abserr in mV)         

 range   expected      read    abserr
   0.0      0.000     0.181     0.181   
   0.5      5.012     5.311     0.299
   1.0     10.024    10.316     0.292
   1.5     15.036    15.314     0.278
   2.0     20.048    20.320     0.272


Excitation 4.999V readings (expected, read and abserr in mV)

 range    expected       read    abserr
   0.0       0.000      0.087     0.087
   0.5       2.500      2.647     0.148
   1.0       4.999      5.146     0.147
   1.5       7.499      7.643     0.145
   2.0       9.998     10.142     0.144


Locking at the results above (for all ranges expect 0.0):

* absolute error is almost 0.146(mV) when Vexc is 5V (5000mV), so 0.00292%, let's say 0.003% * VExc => 0.15mV
* absolute error is almost 0.285(mV) when Vexc is 10V (10000mV), so 0.00285%, let's say 0.003% * VExc => 0.3mV
Note that absolute error for 0.0 range is almost 1/2 (0.003% * VExc)

hozone:
Little updated.
I've notice the 0.272mV shift even on simulator on the R1/R7/R5/R8 branch, given a Vexc of 10V. (see image).
Is it somehow correlated?  :-//

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