fork03
Newbie level 3
I am attaching here a my pt100 gain circuit..
In which i am using lm358 opamp for gain.
First i am calibrating this circuit for 0 - 300'c range.
1) Pt 100 resistance on
0’c -> 100 Ω
300 ‘c -> 212 Ω
First i am putting 100 Ω at input side and changing vr1 till vout will 0v.
Then i am putting 212 Ω at input and changing vr2 till vout will 5v.
2) So now pt100 (0 – 300 ) range calibration has done.
Now as resistance changes my V out will vary from 0 – 5v.
But gain variation is so much that I am getting the range from 2.6 – 1.5 v range.
Please somebody help that why this much non linear gain is coming...
Is this due to lm358 (error prone op-amp) ?
In which i am using lm358 opamp for gain.
First i am calibrating this circuit for 0 - 300'c range.
1) Pt 100 resistance on
0’c -> 100 Ω
300 ‘c -> 212 Ω
First i am putting 100 Ω at input side and changing vr1 till vout will 0v.
Then i am putting 212 Ω at input and changing vr2 till vout will 5v.
2) So now pt100 (0 – 300 ) range calibration has done.
Now as resistance changes my V out will vary from 0 – 5v.
But gain variation is so much that I am getting the range from 2.6 – 1.5 v range.
Please somebody help that why this much non linear gain is coming...
Is this due to lm358 (error prone op-amp) ?