Electret microphone

Using Arduino Audio
1

Hi,

I would like to read a microphones values with the Arduino and build something like this.

I have an electret microphone without any amplifier circuit.
Do I need one and what is the easies way to do that?

I found a TDA2822M and the datasheet says its some kind of amplifier. Is it useful for this project?

Can I use a microphone like this without any additional circuit? I dont have one, so I'd rather make one out of parts I already have.

As I assume Im not the first one to ask this, I would be happy if you post a link to a working circuit.

Here I documented what I tried some months ago without success.

2

All your circuit should work. You just need to make sure that the mic's polarity is correct and the output signal is an ac signal.

You can use a hardware low-pass filter / rectifier or you can do that via software.

3

dhenry:
All your circuit should work.

But they don't and I don't know why.

4

marian42:

dhenry:
All your circuit should work.

But they don't and I don't know why.

Nobody else knows why either... We don't know if the problem is in your microphone, amplifier circuit, or in your firmware/sketch, or somewhere else... In order to troubleshoot your project, you need to test the individual sections and "zoom-in" on the problem.

What's happening? Anything?

Do you have a multimeter to measure the signal out of your microphone amplifier? Maybe try putting +5V on the Arduino input to make sure the Arduino and the firmware are working. (With 5V, I assume the VU meter will max-out.)

Or, maybe add a [u]protection circuit[/u] (two diodes and a resistor) and feed-in an audio signal from somewhere else (bypassing the microphone) .

I found a TDA2822M and the datasheet says its some kind of amplifier. Is it useful for this project?

Maybe... But it has fixed gain, and we don't know how much gain you need. The required gain depends on the sensitivity of the particular mic, and the loudness of the sound. Usually, it's best to have a gain/sensitivity control. And, you'd still need to bias the electret mic.

Can I use a microphone like this without any additional circuit?

That looks like it should work.

I dont have one, so I'd rather make one out of parts I already have.

I'd say your odds are better with something pre-built. :wink:

5

DVDdoug:
Nobody else knows why either... We don't know if the problem is in your microphone, amplifier circuit, or in your firmware/sketch, or somewhere else... In order to troubleshoot your project, you need to test the individual sections and "zoom-in" on the problem.

The last link in the first post leads to a description of what I already tried.

DVDdoug:
What's happening? Anything?

I assembled the circuit again. The arduino always reads a random value between 1000 and 1020.
I connected 3 different microphones, one of them works with my PC. (I dindnt try the other ones) I tried both polarities for each microphone.
Also, I connected the line out of my PC while playing music with the same result.
The only way to get a signal, although a very weak one is to directly connect A0 to the PC and play music at maximum volume. Then it reads a tiny peak at each beat.

DVDdoug:
Do you have a multimeter to measure the signal out of your microphone amplifier? Maybe try putting +5V on the Arduino input to make sure the Arduino and the firmware are working. (With 5V, I assume the VU meter will max-out.)

The arduino works perfeclty with all my other projects.
I hava a multimeter. (I actually bought it to debug this circuit when I tried it the first time)

Do you think its worth trying to put up a circuit with the IC?

6

Could be hardware failure, try to connect analog input directly to on board 3.3V and see what value you get.
Applying AC voltage to any arduino pins, even it coming from your PC sound card , is something Never DO.

7

It reads 680. The A0 pin also works with potentiometers and all other projects.

What is the problem with connecting an AC signal to an analog pin?
Its the closest I ever came to making a VU meter :wink: