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Topic: How to make the LED react on input (Read 9468 times) previous topic - next topic


Hey again
I tryed it with a potentiometer, and i got it to work like i would like with the microphone, but when i connect the microphone again, and change the values, it doesn't work


Well, now we know that your circuit works to measure 0-5V signals.

This probably means that the signal from the microphone is too small relative to the 0-5V amplitude you are measuring, as Mike was saying earlier, I believe.

You will need to amplify it somehow. You should mention this to your professor as how to do this will depend on what parts you have available in class.


I have already amplified the signal, the level is now 0.2V. What do you suggest?


So the arduino measures 0-5V just fine with the potentiometer, and you know you have 0.2V at the amplified microphone, but when you connect the two, the arduino measures 0?

(going to lunch, by the way, so I won't be able to reply for a bit)


I have already amplified the signal, the level is now 0.2V.

Is this measurement taken before you connect it up to the Arduino's input or when it is connected up?

I suspect that the output of your amplifier is being killed by the arduino's input impedance. Have you connected this up through a capacitor like I said earlier or is it a direct connection? Have you connected the -ve supply on your amplifier to the GND on the arduino. Note that GND on the amplifier is NOT the same as GND on the Arduino if you are running it all off the same supply.


everybody, thanks for your help!!!
But my time is done, so i talked to my professor, about it. i choose to simulate it with a potentiometer instead. i've used too long time on this projekt...
so i close this post


Sorry to hear that, better luck on the next one!


I guess we all got an F on that project.  >:(


It was proberbly something I did wrong...
But still thanks, for your help, because of that, i got to know a lot about the arduino, and i think, somehow I will score some more grades :) :) :) ;) ;) ;) ;) ;) ;) ;)...


Sep 26, 2008, 12:47 am Last Edit: Sep 26, 2008, 12:51 am by macegr Reason: 1
I thought I posted this in another thread on this forum...probably would have needed to tweak the amplification a little for the microphone, but it would do the trick:

This one looks a lot better signalwise, but the response really doesn't look as good as the simpler circuit when you actually build it.

Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store


Sep 28, 2008, 01:29 pm Last Edit: Sep 28, 2008, 01:29 pm by oddish2211 Reason: 1
ignore this post, wrong topic


Oct 31, 2008, 07:08 am Last Edit: Oct 31, 2008, 07:10 am by Interesting Reason: 1
Code: [Select]
int val = 0;

void setup()
// note that you should not call pinMode for the analog pins
Serial.begin(9600); // initialise serial port for 9600 baud

void loop()

  val = analogRead(analogPin);   // read the input pin
  delay(250); // delay 1/4 second between readings

Would something like this work over the USB port? Would it give off results?


A microphone does not provide enough signal to drive the analog inputs without amplification. The circuit in the top picture in macegr's post above is an example of what is needed.

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