# OP AMP Gain for complex circuit

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#### Bandit03

##### New Member
Can someone verify the gain of this op amp circuit?
The frequencies I will be testing the circuit at are 1, 10, 100 and 500 Hz.
I would like to know the method and values of the theoretical gain.
The circuit diagram is in the attachment.
Values are
R14 = 3570
R15 = 57600
R16 = 2320
R17 = 59000
L1 = 6 Henries

#### Attachments

• OPAMP_OP77.jpg
17.2 KB · Views: 142

#### ericgibbs

##### Well-Known Member
Can someone verify the gain of this op amp circuit?
The frequencies I will be testing the circuit at are 1, 10, 100 and 500 Hz.
I would like to know the method and values of the theoretical gain.
The circuit diagram is in the attachment.
Values are
R14 = 3570
R15 = 57600
R16 = 2320
R17 = 59000
L1 = 6 Henries

hi,
Is this a school problem.?

#### Bandit03

##### New Member
NO, I am a mechanical engineer and I am trying to understand this op amp circuit in our test stand.

#### ericgibbs

##### Well-Known Member
NO, I am a mechanical engineer and I am trying to understand this op amp circuit in our test stand.

OK, I assume that R15 is the voltage input and R14 is at 0V.?

#### Bandit03

##### New Member
Both have voltages applied to them.

#### ericgibbs

##### Well-Known Member
Both have voltages applied to them.

hi,
This is with one signal on the NINV input.

Whats the voltage level of the two inputs.??

Its a 65Hz notch filter [60 Hz]

#### Attachments

• esp01 May. 31.gif
26.9 KB · Views: 128
• esp02 May. 31.gif
26.4 KB · Views: 102
Last edited:

#### Bandit03

##### New Member
I 've attached an excell file where I did some calculations.

#### Attachments

• singleworksheet.zip
10.4 KB · Views: 52

#### ericgibbs

##### Well-Known Member
I 've attached an excell file where I did some calculations.

Sorry, dont have a XLS reader program.

Do you follow the simulations I posted.?

#### Bandit03

##### New Member
I will need some time to disect, but generally yes.
What program did you use to do the analysis?

The plots looks accurate since the resonant frequency is 64 Hz.

Thanks for your help, the plots should help me know if I calculated the right gains.

#### ericgibbs

##### Well-Known Member
I will need some time to disect, but generally yes.
What program did you use to do the analysis?

The plots looks accurate since the resonant frequency is 64 Hz.

Thanks for your help, the plots should help me know if I calculated the right gains.

hi,

If you do, you can run the attached file.

#### Attachments

• Forum1.asc
1.9 KB · Views: 92

#### Bandit03

##### New Member
Thanks again - your knowledge and help was outstanding and extremely fast.

#### Hero999

##### Banned
Please don't call µF mF, it's very confusing, mF really means 0.001F.

Use µF for values <99,999µF and F for values >0.1F.

If you can't write µ for whatever reason use u.

#### ericgibbs

##### Well-Known Member
Please don't call µF mF, it's very confusing, mF really means 0.001F.

Use µF for values <99,999µF and F for values >0.1F.

If you can't write µ for whatever reason use u.

hi,
Am I missing something, where is the mF, uF stated in this thread.?

#### andy257

##### Member
Erricgibbs : If you look at the original posters attachment of the circuit he is trying to understand you will see hes labeled some of the components. That is what Hero999 is getting at.

#### Bandit03

##### New Member
Eric,

What you provide me was exactly what I needed and you used the values I provided which was correct.

Hero is right the mF should of been uF in the .jpg.

Thanks again for helping a ME out.

#### ericgibbs

##### Well-Known Member
Erricgibbs : If you look at the original posters attachment of the circuit he is trying to understand you will see hes labeled some of the components. That is what Hero999 is getting at.

hi andy,
You are right.

When Bandit posted the actual parts list, where the part notations are correct I ignored the values on the jpg.

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