what would the transfer function of this circuit, where R1=1K, R2= 560R, Rm = 240R and Rt = 530R. and what would be the output voltage. power supply of op-AMP is +5V and -5V.

 

hi T165,
Is this problem a College or Homework assignment?

Moderation.

 

hi T165,
Is this problem a College or Homework assignment?

Moderation.

its not college or assignment, i didn't share complete details i just share part where i am facing problem.
this is the pressure sensor IC MTCS2601, internal diagram. output of my circuit is slightly different form the expected output. i want to make sure if there is mistake.

as shown in above image the original output need to me as blue line but my circuit output is as red line. complete project details would be complex so i just shared part of it.

 

The pressure sensor datasheet ought to have a reference design for how it should be connected. If you use that design, it ought to produce the specified output. If you don’t you are on your own.

How about linking the datasheet for the sensor and a schematic showing how you have it connected it. Then someone here might be able to help.

 

The pressure sensor datasheet ought to have a reference design for how it should be connected. If you use that design, it ought to produce the specified output. If you don’t you are on your own.

How about linking the datasheet for the sensor and a schematic showing how you have it connected it. Then someone here might be able to help.

thanks for reply.
here i attach the datasheet. below circuit is given in datasheet. i exactly copy the same circuit, with one change,
1- option one was that i use +5V and -5V supply for this circuit but i did some thing different.
2- i use 0 to 10V supply and apply fix 5V at positive pin of boath op-amp. in that case mat output was expected to be 7.5V but its different.

 

How did you create the midpoint voltage? That voltage must be stiff, it cannot just be a voltage divider. Have you measured your midpoint voltage when your circuit is operating? If it does not stay at 5V, that is likely your problem.

Disclaimer: I have no knowledge or experience with that type of sensor, but I do have experience with single supply virtual ground op amp circuits.

 

How did you create the midpoint voltage? That voltage must be stiff, it cannot just be a voltage divider. Have you measured yiur midpoint voltage when your circuit is operating? If it does not stay at 5V, that is likely your problem.

Disclaimer: I have no knowledge or experience with that type of sensor, but I do have experience with single supply virtual ground op amp circuits.

Thanks for your reply:
voltage is fix 5V its not with voltage divider, and i also measure it always remain fix 5V. for that i use LM404 diode in series with 13k resistor to get fix 5V. i also attached my schematic too.

 

If indeed it always measures 5V, then that is not the problem, the circuit should work as is.

But, I am skeptical. 13K sounds way too high for the series resistor of the LM404. I would try 1K, which is well within the limits for the LM404 and see if that helps.

Also, what op amp are you using? It might be maxing out, though you have 2.5V of headroom, which should be enough. What is the load on it? Perhaps you are overloading the output.

 

Thanks for your reply:
voltage is fix 5V its not with voltage divider, and i also measure it always remain fix 5V. for that i use LM404 diode in series with 13k resistor to get fix 5V. i also attached my schematic too.

View attachment 330575View attachment 330574

thanks for reply:

If indeed it always measures 5V, then that is not the problem, the circuit should work as is.

But, I am skeptical. 13K sounds way too high for the series resistor of the LM404. I would try 1K, which is well within the limits for the LM404 and see if that helps.

Also, what op amp are you using? It might be maxing out, though you have 2.5V of headroom, which should be enough. What is the load on it? Perhaps you are overloading the output.

thanks for reply.
1- yes i will change resistor to make sure it, according to datasheet this resistor is also ok and i also make sure by measuring the voltage that always remain stable 5V. as you said 1K would more better.

ap-amp i am using is : TS922, this op amp is rail to rail op-amp.

 

Hi T165,
Is this LTSpice simulation of your circuit a close approximation?, please advise of any correction required.
E

 

what would the transfer function of this circuit, where R1=1K, R2= 560R, Rm = 240R and Rt = 530R. and what would be the output voltage. power supply of op-AMP is +5V and -5V.

Hi T,
Answering your original question.
This is what LTS shows for Vo.
E

 

See

 

Hi Alex @Bordodynov

I am using the TS922 OPA Spice model, as shown in the TS's circuit of post #7, I am puzzled why my LTSpice simulation gives a different plot result as your post image #12.?

E

 

Hi Alex @Bordodynov

I am using the TS922 OPA Spice model, as shown in the TS's circuit of post #7, I am puzzled why my LTSpice simulation gives a different plot result as your post image #12.?

E
View attachment 330608

Post your .asc file

 

Hi ee,
As requested files attached, ask if you require additional info.
E

 

Hi ee,
As requested files attached, ask if you require additional info.
E

thanks

 

See

 

Hi Alex.
Same opa LM324, different plots??
E

 

See

 

Hi Alex,
Why did you post #17 with a circuit did not produce the plot?
This plot is also different from your post #19 plot.

I am trying to determine the cause of the problem .
E