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EKG circuit

Sait hakanoglu
Prodigy 25 points
Other Parts Discussed in Thread: INA333, ADS1298

Hi there, I'm going to design EKG as a project for my FBE course, I found a circuit diagram in this link, http://www.picotech.com/applications/ecg.html#safety  , what do you think about it? it seems to be simple one with some forgotten parts on it, I mean do we need any other parts such as filters and etc to use with this circuit schematic or it works properly without any other parts?

  • 0
    TI__Guru 62895 points

    Hello Sait,

    I agree this seems to be a very simple ECG circuit that may get you started in the correct direction.  In addition to the components shown I imagine you would require the following:  Differential and Common-mode input filtering, AC Coupling with an integrating servo amp or an AC couple capacitor, Right Leg-Drive, Wilson Central Terminal, and several other circuit components.  Below is an example using the INA333 and other supporting components:

    There are a number of ECG/EKG/EEG related posts on the forum already with circuits and significant dialogue.  I strongly suggest you search and read through those before you start your project.

    Regards,
    Collin Wells
    Precision Linear

  • 0 in reply to Collin Wells
    Prodigy 25 points

    Thanks a lot dear Collin, It seems to be a complete ecg circuit, I wish to start implementing it very soon!

    But I have some problems here, is it necessary to use normal battery for each +Vs input of opamp because of safety or we can use normal DC voltage sources that we normally use in lab experiments?

    What is the function of ac/dc switch under the INA333?

    How should we choose the amount of RG ?

    Thanks

     

  • 0 in reply to Sait hakanoglu
    TI__Guru 62895 points

    Hello Sait,

    You will have to determine the safety requirement of your final product and ensure that unsafe voltages do not ever reach the user (or yourself). 

    The switch goes between AC and DC coupling of the INA.  DC coupling grounds the reference, AC coupling connects the reference to the output of the AC servo integrator.

    You will need to choose RG based on the desired gain in your system. 

    As mentioned before, please consider reading through ALL of the ECG/EKG posts on this forum as well as the Precision Data Converter Forum.  I suspect you will find answers to most of your questions as well as several common mistakes and lessons learned during the design of these systems.  You may also consider looking at the ADS1298 which is an Analog Front-End (AFE) specifically designed for ECG applications.

    Regards,
    Collin Wells
    Precision Linear Applications