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I am using an INA121 instrumentation amplifier, and its output is 156 mV, but it is not seen in the microcontroller, it is just giving 0 like:

I increased its output voltage (gain) by decreasing the gain resistor value, but it did not work. Because of this, even if I amplify with other amplifiers, it is keeping the reference point 0 and shows signals like this:

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Normally it should be like this:

enter image description here

Can you help me?

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I have added an amplifier to amplify 2 times (IC4) and used the output from there, but it is optional to use it. IC$ is used also as a Driven Right Leg circuit.

ocrdu
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Merve Özdaş
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    Merve Özdaş - Hi, You already have [this active question](/q/673619) which seems related to your new one here, as [one of the images](https://i.stack.imgur.com/e6bor.png) looks the same. Please edit *both* of your questions to explain why you need two active questions at the same time & explain if & why there is any overlap between them. || FYI it generally annoys people if they answer one question and then find something in another related question (which they didn't see) that affects the answer they wrote. Please ensure that your questions do not duplicate each other *in any way*. Thanks. – SamGibson Jul 12 '23 at 20:56
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    @merve Please post a schematic – Voltage Spike Jul 12 '23 at 20:59
  • okay I am putting in answers @Voltage Spike – Merve Özdaş Jul 12 '23 at 21:13
  • @MerveÖzdaş Please edit the question. Thanks – Voltage Spike Jul 12 '23 at 21:15
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    INA121-REF pin needs to be connected to 0V/GND. Can't be left floating. From INA121 Datasheet "The output is referred to the output reference (Ref) terminal which is normally grounded. This must be a low-impedance connection to assure good common-mode rejection. A resistance of 8Ω in series with the Ref pin will cause a typical device to degrade to approximately 80dB CMR (G = 1)." – elchambro Jul 13 '23 at 00:33
  • Why do you expect a DC component after AC coupling? –  Jul 13 '23 at 11:12

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