Hello,
I am working on a circuit for a project that requires an audio input into an electret microphone to feed into an instrumentation amplifier (AD620A), which has a high CMRR and also provide a gain of 50 V/V. My problem is that the two of these components integrated does not work. At first the microphone output did not feed into the AD620A op-amp (it was in the range of mV) so a buffer (LM741) was added. It still didn't work, but after much research a 10 k ohm resistor was added, which I'm also not exactly why it worked. I guess it provided an alternative path for the current to flow to ground. And, I kept the buffer because it gave a much better output than without it. Now, although there is an output from the AD620 op-amp, it only yields a gain of 2 V/V versus 50 V/V. I have been working on this for quite some time. Any help would be very much appreciated. Thank you and have a good day! I've attached the circuit.
I am working on a circuit for a project that requires an audio input into an electret microphone to feed into an instrumentation amplifier (AD620A), which has a high CMRR and also provide a gain of 50 V/V. My problem is that the two of these components integrated does not work. At first the microphone output did not feed into the AD620A op-amp (it was in the range of mV) so a buffer (LM741) was added. It still didn't work, but after much research a 10 k ohm resistor was added, which I'm also not exactly why it worked. I guess it provided an alternative path for the current to flow to ground. And, I kept the buffer because it gave a much better output than without it. Now, although there is an output from the AD620 op-amp, it only yields a gain of 2 V/V versus 50 V/V. I have been working on this for quite some time. Any help would be very much appreciated. Thank you and have a good day! I've attached the circuit.
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