need explaination in my circuit

Discussion in 'General Electronics Chat' started by alapeh, Apr 3, 2012.

  1. alapeh

    Thread Starter New Member

    Mar 17, 2012
    9
    0
    hi all electronics experts and pros.. i need some explanation on my ecg circuit.

    this is my ecg circuit diagram.
    please kindly help me as i am not very sure.
    i need advice and explanation

    [​IMG]


    from what i know, op amp 1 is rc low pass filter,
    electrode 1 connects to op amp 3 and its a non inverting op amp for amplifying.
    electrode 2 connects to op amp 5 and its a non inverting op amp for amplifying.
    electrode 3 connects to op amp 6, it is a invering op amp.

    what about op amp 2 and op amp4? what are they acting as, what are they use for in this whole circuit? are they also amplifying? i thought op amp 3,5,6 are already amplifying? can and pro explain to me ?

    can any 1 also please explain my whole circuit and let me have a better understanding ? :confused::confused::confused:

    i really appriciate it. thanks!:)
     
  2. alapeh

    Thread Starter New Member

    Mar 17, 2012
    9
    0
    can any1 help ?
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,765
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    Have patience. Quality answers take a while. Quick answers may not be what you want.
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    An old 741 opamp is too noisy to be used in an ECG circuit. The resistors in the circuit must be extremely well matched.

    Therefore an instrumentation amplifier IC has been used for many years. It has low noise opamps and extremely well-matched resistors built-in.
     
  5. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    Could you please upload a diagram with higher resolution. Labels such as signal names and some other values cannot be read reliably with the present diagram.

    For instance, this thing seems to be running off a single 5V supply, ( too low ) and the extra amps may be to establish a half - rail, but we can't really see.

    PS some of the wire crossings look like JFETS - very confusing at first glance!
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,432
    3,360
    Why do you call this "my" circuit if it is not your circuit?
     
  7. alapeh

    Thread Starter New Member

    Mar 17, 2012
    9
    0
    http://picturepush.com/public/7973490

    this website show a clearer version of my circuit,

    i used 741 for simulation purpose only.
    i admit that i am not very good in my electronics. this circuit was plan and design with my project supervisor. however, i need to understand the whole thing before my project presentation.

    Thank to those who help me with this!
     
  8. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  9. alapeh

    Thread Starter New Member

    Mar 17, 2012
    9
    0
    thanks for the help, can any 1 tell me what is op amp 2 and op amp acting as ?

    and i am right to say that, op amp 3 ,5 and 6 act as a instrumental amplifier and op amp 1 is a rc low pass filter.?

    thanks!
     
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