electret microphone constant voltage output

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1

I’m using the same microphone and amplifier circuit that is on the Sparkfun Electret Microphone breakout board: https://www.sparkfun.com/products/9964

I built this circuit using the same parts except the microphone is a different part (CMA-4544PF with datasheet at http://www.cui.com/product/resource/cma-4544pf-w.pdf) and VCC is at 3.3V.

I am getting a constant voltage at the output of the microphone. I set the scope to AC coupling with 5 mv/div and I just see noise. I checked all the connections and VCC/ground. I have built this circuit before and it worked, and I have no idea what could be wrong now. Any ideas about common problems or possible sources of error with a circuit like this?

2

How sure are you that pin 1 of the mic is connected to R1/C1 ? That pin 2 is connected to ground ?

3

I hope this isn’t too obvious, but is the microphone polarized? How do you tell which is pin 1?

4

thankyou:
I hope this isn’t too obvious, but is the microphone polarized?

According to the link to the PDF you posted, it is.

thankyou:
How do you tell which is pin 1?

The mechanical drawing at your link shows some sort of green marking nearer to pin 2 than to pin 1.
5

Haha wow, THANK YOU SO MUCH!!! There is no color on the datasheet I see, but I just read that the metal casing of an electret microphone is grounded. I just measured the resistance from the case to the pin that was presumably ground, and it’s not connected!!! It’s connected to the other pin! So it’s backwards…amazing…