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Old 06-20-2011, 03:07 PM
@m@ @m@ is offline
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Default XR2206 function generator circuit connecting with Instruementation amplifier

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 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...
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Old 06-20-2011, 03:46 PM
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beenthere beenthere is offline
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We need to see a complete schematic to be able to see what might be wrong.
First comes the hardware, then the software.
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Old 06-20-2011, 06:07 PM
Audioguru Audioguru is offline
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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.
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Old 06-20-2011, 06:17 PM
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t06afre t06afre is offline
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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
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Old 06-20-2011, 07:19 PM
@m@ @m@ is offline
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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
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Old 06-20-2011, 10:02 PM
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You have been answered. The answer is: AC couple the output of the oscillator.
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Old 06-21-2011, 12:10 AM
mozikluv mozikluv is offline
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Default Xe2206

isolation indeed
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Old 06-21-2011, 08:03 AM
@m@ @m@ is offline
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oka thanks for the help ...!
i will try this & then will inform u ppl , that it is working or not...
thank u..
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Old 06-22-2011, 11:51 AM
@m@ @m@ is offline
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thanks every1 its working
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