XR2206 function generator circuit connecting with Instruementation amplifier

Discussion in 'The Projects Forum' started by @m@, Jun 20, 2011.

  1. @m@

    Thread Starter Member

    Mar 9, 2009
    hello to everyone...!

    I have made function generator circuit using XR2206 and it works perfectly with varying frequencies of 20Hz-20KHz.. But the the problem is that when i connect this function generator output to the input of AD620 (pin 3) having Rg=100 then there is no output at the pin 6 of AD620 [​IMG] whereas when i connected the same fucntion generator output to my low pass butterworth filter (Fc = 25 Hz) then its working as well as showing excellent frequency response.. I am just stuck here ... what's the problem with AD620...? ( my AD620 circuit is working fine when input is given by lab Function generators)

    Thank u...:confused:
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  2. beenthere

    Retired Moderator

    Apr 20, 2004
    We need to see a complete schematic to be able to see what might be wrong.
  3. Audioguru

    AAC Fanatic!

    Dec 20, 2007
    The XR2206 uses a single-polarity supply so its output is at a positive voltage.
    The AD620 probably has a dual-polarity supply so its DC gain is amplifying the DC output of the XR2206 which causes the output of the AD620 to be slammed as high as it can go.

    Simply add a coupling capacitor between them to block the DC but pass the AC. The input of the AD620 will need a resistor to 0V.
  4. t06afre

    AAC Fanatic!

    May 11, 2009
    The 620 is a Low Power Low Drift, Low Power Instrumentation Amp with Set Gains of 1 to 10000. I do not know what you try to create. It may be that it is ok. But are you sure the Instrumentation Amp is the correct thing to use in your application
  5. @m@

    Thread Starter Member

    Mar 9, 2009
    Actually I am making circuit for EEG .. the need of function generator is just for checking my circuitry through sine wave input and to check out my filter responses that either they works f9 or not and the first stage of my circuit is AD620 (I.A) ,if AD620 will not show output for this function generator then how i will be able to check my whole circuit... :( It was not so hard to make function generator :( .. Ryte
  6. #12


    Nov 30, 2010
    You have been answered. The answer is: AC couple the output of the oscillator.
  7. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    isolation indeed:)
  8. @m@

    Thread Starter Member

    Mar 9, 2009
    oka thanks for the help ...!
    i will try this & then will inform u ppl , that it is working or not...[​IMG]
    thank u..
  9. @m@

    Thread Starter Member

    Mar 9, 2009
    thanks every1 its working :D