Hi all,
I have constructed a small microphone preamp for an electret condenser. According to the simulations I ran prior to putting the circuit together, the setup should work as intended, which it is not. (In order to analyze the amplified microphone data, I am using a microcontroller to read the data into my computer where I view the output on screen).
Foremost, instead of getting constant "center" unamplified values when the microphone is not receiving sound, the input indicates that the microphone is outputting a voltage. When I increase the op-amps gain, this idle value increases accordingly instead of remaining relatively the same. For example, if a central value of 512 indicated 0 voltage output from the microphone, I would receive a constant value 550-700, depending on the gain that I set.
Furthermore, the only time I am able to detect a change in these values is when I make physical contact with the microphone or blow on the microphone -- simply talking into it does nothing.
Does anyone have any hypotheses as to why this might be happening? Below is the schematic of my preamp circuit. I am using the microcontroller's 5V power supply to power both the op-amp and the mic.
Thanks you in advance,
Andy
I have constructed a small microphone preamp for an electret condenser. According to the simulations I ran prior to putting the circuit together, the setup should work as intended, which it is not. (In order to analyze the amplified microphone data, I am using a microcontroller to read the data into my computer where I view the output on screen).
Foremost, instead of getting constant "center" unamplified values when the microphone is not receiving sound, the input indicates that the microphone is outputting a voltage. When I increase the op-amps gain, this idle value increases accordingly instead of remaining relatively the same. For example, if a central value of 512 indicated 0 voltage output from the microphone, I would receive a constant value 550-700, depending on the gain that I set.
Furthermore, the only time I am able to detect a change in these values is when I make physical contact with the microphone or blow on the microphone -- simply talking into it does nothing.
Does anyone have any hypotheses as to why this might be happening? Below is the schematic of my preamp circuit. I am using the microcontroller's 5V power supply to power both the op-amp and the mic.
Thanks you in advance,
Andy
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