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EMG circuit problem

Other Parts Discussed in Thread: OPA2132, INA2126, OPA2604, INA2128

5355.EMG AMPLIFIER CIRCUIT DIAGRAM FOR ONE CHANNEL.doc

 

Hi,

 

I made a design of surface EMG and that circuit as attached.  In this circuit i used INA2126 for behalf of INA 2126 and OPA2132 for OPA2604. But i cant see clear variation of the signal. so can you pls tell me what kind of changes should to success this circuit with INA2126 and OPA2132.

I used INA2126 because INA2128 not availble in the markrt

 

Pls help me and reply me soon sir,...................

 

Lakmal

  • Lakmal,

    I don't see any major errors in you circuit. I recommend that you probe the output of U1A to see the signal after this first gain stage. Make sure that there are no oscillations and the the op amp is operating in its linear output range.

    If you see oscillations, the problem could be due to the connection from R1/R2 to U2A. Put a 10k resistor in series with pin 3 of U2A and locate it close to R1 and R2.

    Your schematic appears to connect pin 2 of U1A to the shield of the input cable. You should use the output of U2A to drive the shield. Both inputs of U1A should be inner conductors of the cable.

    I hope this helps.

    Regards, Bruce.