Electret Microphone Breakout Board

Hi !

I want to read the voice through this microphone using Micro-conroller ADC channel.
I have one question about this which is : Do I need to use any type of amplifier with it??
It is said in pololu that this microphone has a built in 100x opamp and it will output an amplified analog signal. Is that built in opamp enough or I need to connect an amplifier to it??

Thanks in advance.

Regards,
Raghad

Hello.

As you saw on the product page, it has a built-in amplifier, but whether you need more amplification than this really depends on your application. If you will be speaking into the microphone or somewhere very close to this, the built-in amplifier should be sufficient. If you will be across the room, it probably won’t be. If you have access to an oscilloscope, you can look at the outputs to see what kind of signal you’re getting.

- Ben

Hi!
Thanks Ben for the reply :slight_smile: . I have connected the microphone to my ADC controller channel and I have supplied the microphone with GND and 5 V. Actually I am getting nothing from the microphone and I also checked ADC channel with Oscilloscope but it gives nothing. All I get is a value of 1023 on the display. Actually I wanted to display the ADC value from microphone but I get only that number and it does not change.
Can Anyone help me with this please!!!

Thanks in advance.

Regards,
Raghad

If you have an oscilloscope, I suggest you disconnect your Arduino completely and just use your scope to try to get some response from the mic. Unfortunately, the mic is not very complicated, and if you don’t see any output when you connect 5V to Vcc and ground to GND, I’m not sure what else to suggest. Is there any chance you initially connected things wrong or used the wrong voltages? The manufacturer of the part is likely to be able to give you better troubleshooting assistance, so I suggest you contact Sparkfun directly if you continue having problems.

- Ben

Hi Ben!

Now I got the microphone working.

Thanks.

Raghad

Was the microphone damaged or were you just doing something wrong?

- Ben

Hi Ben!

The problem was that one of my group members did not apply a good soldering to the ground pin.

Another question appears now: Will the performance of the microphone change if the supply voltage is 3.3V ??
The supply voltage for the microphone in datasheet is from 2.7 to 5.5, but I am connecting it to my Evk1100 board that is 3.3v. As you know that I use ADC channel to read the microphone values. When I connect it to my board(3.3 V) I get 512 as the maximum number from The microphone, but when I connect it to 5 V then I get the maximum number up to 1023. The ADC channel that is on the board is 10 bit(which means the maximum i can get is 1023) but when I connect the microphone to 5V , then I get the max. value 512, which means 9 bit. Will that affect the performance of the microphone!!??

Regards,
Raghad

The microphone board uses an opamp with 0 - Vcc rails, so the output will be between 0 and Vcc. I don’t expect Vcc to affect the sensitivity of the microphone, but all the information I have to go on is what is on our product page.

- Ben

Thank you very much for the reply :slight_smile: . I think That I can only use 3.3 V in my case… Thanks a lot for the help you provided Ben. Your help ave me a better understanding for a lot of things :slight_smile: .

/Raghad

I hope no one objects to my re-visiting this issue. I, too, am attempting to use the Electret Microphone Breakout Board for a sound activated project. I have connected the breakout board to an Arduino Mini04’s ADC channel0 pin. Both the Arduino Min04 and the microphone breakout board are powered by the voltage coming from a host PC’s USB port via a FTDI Friend USB-to-serial board from Adafruit. The FTDI Friend board is also providing connection to the Arduino Mini for the Arduino IDE, as well as being the Serial port over which the Arduino Mini is returning values from its ADC.

For the record, I am getting signal from the microphone breakout board, and I can see it both on an oscilloscope and via the ADC function on the Arduino Mini, so I know the microphone breakout board is working. The “gotcha” is, I only see signal from the microphone breakout board if it is placed about 3 inches or less from a speaker. Is this the expected performance for this microphone? I was hoping to get a response from about 12 inches from a sound source.

Thanks!
Dave