Gain in ina114 is not obtained

Discussion in 'The Projects Forum' started by nakulnasa, Oct 16, 2010.

  1. nakulnasa

    Thread Starter New Member

    Oct 15, 2010
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    Hi i am using ina 114 for my signal conditioning circuit.According to the calculation the G=1+(50k/Rg). When i set the Rg value to 50k the gain must be 2 an if i give 10 mv of input to the non inverting terminal the output must be 20mv but the output is 647mv till the input is 550 mv. Can any body help me out.
     
  2. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Post your schematic.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    The INA114 requires a dual-rail supply; it will not work properly with a single supply.

    If you must operate an instrumentation amplifier with a single supply, you need to select a different model.
     
    nakulnasa likes this.
  4. nakulnasa

    Thread Starter New Member

    Oct 15, 2010
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    Thanks for ur information. I have now optimized my circuit for ina 114 using single supply. I have made an virtual ground with vcc/2 (using the voltage divider circuit) to the inverting terminal (PIN 2)and i have connected the Vref (PIN 5) of ina114 to the virtual ground. And by giving the input to non inverting terminal (PIN 3) with respect to the virtual ground and by measuring the output from the Vout (PIN 6) with respect to the virtual ground i am obtaining the gain exactly what required(only the range of the output voltage is reduced to 0v-1.5v when vcc is 5v, and 0v-3v when vc is 12 v). I want to provide the input and measure the output with respect to the system ground. Is this possible can u please help me out...


    Thank you..
     
  5. nakulnasa

    Thread Starter New Member

    Oct 15, 2010
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  6. nakulnasa

    Thread Starter New Member

    Oct 15, 2010
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    Last edited: Oct 21, 2010
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Sure. Add a negative supply rail, and get rid of your virtual ground.

    Either that, or get an instrumentation amplifier that is rated for single-supply operation who's input and output range includes ground.
     
  8. nakulnasa

    Thread Starter New Member

    Oct 15, 2010
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    Thanks...Since my circuit is battery powered i cannot go for the negative supply , i have to work with the single supply....
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    So use two batteries in series, with the junction in between them grounded.

    Or, use a DC-DC converter like an ICL7660 to generate a negative rail from the positive rail.
     
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  10. nakulnasa

    Thread Starter New Member

    Oct 15, 2010
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    Thanks ..i got the output...
     
  11. zabeeb

    New Member

    Dec 15, 2014
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    i m using INA114 in my project but i cant find it in proteus software . any one please help me how can i add this or other options to use this in simulation .
    Thanks
     
  12. zabeeb

    New Member

    Dec 15, 2014
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    how did u made INA 114 in prepteous ??? can u please tell that to me
     
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