LM358 module - how to connect?

Hi,

can anybody help me connect a condenser mic to a LM358 module to the Arduino.

I have a LM358 module like the one at http://www.wayengineer.com/index.php?main_page=product_info&products_id=2981

I have the VCC and GND connected and the power led comes on but no matter how I connect the IN and OUT connectors I do not get a proper signal to the Arduino.

At the moment: I have the mic connected to IN and GND (GND on the mic to GND) (I have tried the other way as well). I have the OUT connected to pin A2 on the Arduino

I get a reading of around 500 (the value fluctuates between about 490 and 520). Changing the onboard pot does not effect the value. EDIT - just found out I get the same reading when the mic is not connected.

I have contacted the company I purchased it from and they don't know. Even though they sell it as Arduino compatible.

Provide a schematic of what you’ve done.
Doing this stuff verbally, and with all that back-and-forth, is a waste of time.
Draw a picture of your circuit, take a decent picture of that and upload it as an attachment.

A condenser (electret) mic requires power.
It’s not like a crystal mic.

In my dwg, attached, there are some biasing resistors and coupling caps.
“+V” should not be greater than 3V.
If you don’t like it, google for others.

electret_mic_2.JPG

I get a reading of around 500 (the value fluctuates between about 490 and 520). Changing the onboard pot does not effect the value. EDIT - just found out I get the same reading when the mic is not connected.

That's sort-of a good thing... With no signal the Arduino ADC should by biased at 2.5V (half of the full-scale 1023 reading with the default 5V reference). ...I didn't see anything in the amplifier modual discription saying that.

Now, you just have to get a signal from your mic to the amp, and the readings shoul jump-around, centered around approximately 512.

Get a "dynamic microphone". The condensor mic needs up to 48 volts to provide static electricity. Or maybe 5 volts... Read this...

http://en.wikipedia.org/wiki/Phantom_power

Hi,

here’s the circuit:

Here’s the sketch I am using to test:

int micPin = 1;
int micVal = 0;
int oldMicVal = 0;
int micMax = -9;
int micMin = 9999;

int ledPin = 13;


void setup() 
{
  Serial.begin(9600); 
  while (!Serial)   {  ; // wait for serial port to connect. Needed for Leonardo only
                       }
  pinMode(ledPin, OUTPUT);                   
}



void loop()
{
  micVal =  analogRead(micPin);   
  if (micVal >560)            {  digitalWrite(ledPin, HIGH);  delay(100);   digitalWrite(ledPin, LOW);    } 
  if (micVal > micMax )     {  micMax = micVal;  }
  if (micVal < micMin )      {  micMin = micVal;   }
  
  Serial.print("\nmicVal = ");Serial.println(micVal); 
  Serial.print("micMax = ");Serial.println(micMax); 
  Serial.print("micMin = ");Serial.println(micMin); 
  delay(10);
}

and here is the output I am getting:

micVal = 515
micMax = 529
micMin = 502

micVal = 514
micMax = 529
micMin = 502

micVal = 527
micMax = 529
micMin = 502

micVal = 511
micMax = 529
micMin = 502

micVal = 513
micMax = 529
micMin = 502

micVal = 513
micMax = 529
micMin = 502

micVal = 508
micMax = 529
micMin = 502

I get the same values when I remove the mic.

AmbiLobe: Get a "dynamic microphone". The condensor mic needs up to 48 volts to provide static electricity. Or maybe 5 volts... Read this...

http://en.wikipedia.org/wiki/Phantom_power

WTF!

http://www.epanorama.net/circuits/microphone_powering.html

Don't post if you don't know anything!