Load cell and signal conditioning

[A.Rashad]

I am working on czl-601 load cell which gives me maximum o/p of 24 mv if i give supply voltage of 12 v(2mv/v ). I want this to be interfaced to lpc2148 inbuilt ADC, I need to amplify this 24 mv signal to 3.3 volt , i used opamp741 in inverting amplifier mode with gain of (3300/24==>137.5), but without connecting anything at opamp input it is giving output of 1.8 volt , how ca i achieve 0 to 3.3 volt by 0 to 24mv ? suggest any circuit ?

 

[alexan_e]

Why did you use an inverting amplifier, you have a low positive input and you want a higher positive output so a non inverting amplifier seems to be the proper solution.

https://en.wikipedia.org/wiki/Operational_amplifier#Non-inverting_amplifier

You should use a precision opamp that has a low input offset because your input level is low and you have to use a high gain.

You can also use an instrumentation amplifier like AD620
https://www.analog.com/en/specialty...tation-amplifiers/ad620/products/product.html

 

[A.Rashad]

Why did you use an inverting amplifier, you have a low positive input and you want a higher positive output so a non inverting amplifier seems to be the proper solution.

https://en.wikipedia.org/wiki/Operational_amplifier#Non-inverting_amplifier

You should use a precision opamp that has a low input offset because your input level is low and you have to use a high gain.

You can also use an instrumentation amplifier like AD620
https://www.analog.com/en/specialty...tation-amplifiers/ad620/products/product.html

hello,
I tried with AD620 , i connected a resistor of 330 ohms to achieve a gain of 140 , i connected +5v at pin no. 7 , ground at pin 4 and pin 5 and output of load cell (positive green wire to pin 3 and negative white wire to pin2) but I am getting 0.64 volt at pin no 6 constant with no change , even if i apply weight on load cell ,(input is geting increase to 10-15 mv but constant o/p of 0.64 V ) ?
Do i need to short pin no 2 to ground?

 

[alexan_e]

AD620 needs a symmetric power supply

Wide power supply range (±2.3 V to ±18 V)

 

[A.Rashad]

Thank You alexan_e, it worked now.

---------- Post added at 11:49 ---------- Previous post was at 11:48 ----------

AD620 needs a symmetric power supply

Thank you it worked now

 

[hiremathpraveen1]

hi,
even i am facing same prob as mentioned above, am using "ina 118" here please suggest me

thamk you
praveen

 

[dhanraj_kmr]

Thank You alexan_e, it worked now.

---------- Post added at 11:49 ---------- Previous post was at 11:48 ----------



Thank you it worked now

Can you share the circuit diagram with us?

Atleast a paint diagram..