INA332 help

Discussion in 'The Projects Forum' started by techspark, Dec 24, 2012.

  1. techspark

    Thread Starter New Member

    Dec 24, 2012
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  2. WBahn

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    Mar 31, 2012
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    Please don't hijack someone else's thread. If you can't find an answer to your question by searching the forums, then start your own thread.
     
  3. bertus

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  4. techspark

    Thread Starter New Member

    Dec 24, 2012
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    sorry as m new to usn forums i cudn find wher to start 4m.. so thot of dis
    nxt time wil tc
     
  5. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Well that is actually pretty much a rule on every forum on the internet but perhaps this is the very first forum you have ever posted to.

    In addition please post using full words and not texting language if you want to be understood by every one. This includes starting your sentence with a captial letter and ending it with a period. Please do what you can to help others to help you with your questions. There are folks on here that might have difficulty with text. There are plenty of people to help. If you are not easily understood then they could pass you over and move on to the next person. Besides it is just simple courtesy on your part.

    The other thing to get people to help is do some work on your own like, what you think the circuit should do or what you want to do.
     
  6. ramancini8

    Member

    Jul 18, 2012
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    If you can't take the time to spell correctly, I won't take the time to answer!
     
  7. WBahn

    Moderator

    Mar 31, 2012
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    I get the gist of what you are saying, but I can't figure out much of it. Electronics and engineering involves the communication of very specific thoughts and information. Use this as an opportunity to practice communicating in complete, well-formed sentences. Besides, this is an international forum and many people here (possibly even you) struggle with English as a second (or later) language. Trying to deal with something that smacks of teen text talk is more than many people are willing to do -- they simply move on to someone they perceive as being more deserving of assistance.

    The same goes for posting your efforts. The more you present, the more time people here are willing to put into assisting you. It also provides an invaluable starting point because we can see where your thinking is coming from, what concepts you seem to have a handle on, what level you are working at, and specific places where you are going astray.
     
  8. techspark

    Thread Starter New Member

    Dec 24, 2012
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    So many replies but all on not using texting language and stuff. Expected explanation regarding the circuit.
    Anyways regarding the circuit:
    I basically want to amplify the low frequency ecg signals using this circuit and just wanted to know it's working.

    Thanks
     
  9. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Instead of complaining about what is expected of you maybe an apology is in order?

    See above the more information you can provide the better chance you will get an answer. But even after providing enough information, that does not guarantee and answer.
     
  10. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    OK, I'll tackle this.


    Not shown in the original schematic are the power supply connections, but we can deduce, from the fact that a virtual ground is used, that this circuit uses a single 5V supply. I have added these connections to the schematic.
    R1 and R2 form the virtual ground (VR), used for biasing all the op amp inputs halfway between the supply rails. U3 is a voltage follower, and, if it is connected, biases the entire body at VR (2.5V). Otherwise, R5 and R6 provide the common-mode bias for U1.
    U1 is the differential instrumentation amplifier that amplifies the difference in the millivolt-level signals from the arms, while rejecting any common-mode EMI noise that the body picks up, primarily the mains frequency and its harmonics. These signals come in through R3 and R4. The gain of U1 is 5, set internally.
    It is necessary for U1's output to be centered around VR. This is done with the integrator consisting of U2, R7, and C1. The output of U1 is basically compared with VR, which is on the +input of U2, and the difference is low-pass filtered and amplified by the integrator and fed back to the REF input of U1. This feedback loop forces the long-term average of the U1 output to be at VR.
    U4 and the four resistors connected to it form an inverting amplifier with a gain of (R11/R8) 100. This gain is low-pass filtered by the combination of R11 and C2, with the corner frequency being at Fc=1/(2*pi*R11*C8)=100Hz.

    Therefore, the overall gain is 5*100=500.
     
  11. techspark

    Thread Starter New Member

    Dec 24, 2012
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    hello Sir and thanks alot.
    Sir but I have a question what is the value of Rg?
    also Sir I tried this circuit but I am getting all noise and not a perfect ecg graph.
    Can you help out Sir?
     
  12. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Can you tell my why you make two threads in the same forum on the same thing?
     
  13. Ron H

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    Rg is zero ohms in the schematic you posted.
     
  14. techspark

    Thread Starter New Member

    Dec 24, 2012
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    thanks alot sir.
    but still I m getting noise.
    and what is that shutdown pin?
     
  15. techspark

    Thread Starter New Member

    Dec 24, 2012
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    Did I? sorry den.
     
  16. techspark

    Thread Starter New Member

    Dec 24, 2012
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    sorry den.
     
  17. Ron H

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    Apr 14, 2005
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    I don't know what you are apologizing for.:confused:
    A den is a cave that wild animals live in. Or, it could be a room in your house.
    I think the word you are looking for is 'then'. You may recall that we don't like text speak here.

    Have you looked at the datasheet for the INA332? The shutdown pin is described there. The datasheet should be your first resource for questions about a part. If you don't understand it, come here with your questions.
     
  18. techspark

    Thread Starter New Member

    Dec 24, 2012
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    I am trying to get rid of the habit of not using text language but somehow I end up doing same.
    I connected V+ to the shutdown pin i.e +5v. I refer the datasheet.
    Is it correct?
     
  19. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Yes, that's correct.:)
     
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