Help me about load cell amplifier

[ikramjadoon]

Please configure the resister value for opa2277 load cell amplifier circuit. Load cell 200 kg input supply 10 v output 3mv / v.
Thanks

 

[esp1]

hi,
Are you considering building a Bridge INA amp, using two OPA2277.?
If so, the resistors must be close tolerance values.
The Gain formula is shown in this clip from the d/s.

E

 

[ikramjadoon]

Thanks for reply .but I m confused for (v1 and v2) . What means for that.

In the formula v out= (v1-v2)(1+R2/R1). So v1 and v2 what means. Please explain.
Thanks

 

[KlausST]

Hi,

V1, V2, R1, R2 all is clearely described in the schematic.

****
In post#1 you ask for resistor values, so you should show a circuit, too.

Post#2 is more clearely than post#.

Klaus

 

[ikramjadoon]

From v1 means 3mv or 30 mv ???
And from v2 zero .??
???

 

[esp1]

hi,
Assume a L/C excitation voltage of 10Vdc and L/C bridge sensitivity of 3mV/V
Also the mass being weighed is 200kG.

The L/C bridge would give an output of 3mV * 10Vext = 30mV at FSD of 200kG on the two Signal V1 ,V2 wires from the bridge.

Say you required an amplified voltage output of 5V, the amp would require a Gain of Vout/30mV = 166.67'

Choose R2 as 20k, this means that R1 would have to be in the order of 120R.

Plugging these values into the Vout = (V1-V2) * ( 1+ (R2/R1)) .

Vout = 0.03 * (1 + (20,000/120)) = +5.03V

E

EDIT:
This LTSpice sim shows your project.
It is IMPORTANT that the resistors are close tolerance, ideally 0.01%