breath sensor to control LED brightness

Other Hardware Sensors
1

Hi forum.

I should preface this post by saying I'm new to coding...new to the Arduino (started a couple of weeks ago)...and new to posting on forums.

I've been trying to make this thing that makes an LED increase its brightness dependent on the 'intensity' of a breath [then dim at a constant rate until its breathed on again but that's another part I'm not concerned with yet]...like breathing on hot coals.

I've written some code that handles the RGB/brightness part of the equation but now I'm having a hard time with the breathing input.

What's the best way to capture that breathing "data"?

I've tried:

  1. a piezo wired up like this:

    http://leucos.lstilde.org/wp/2009/06/piezo-transducer-signal-conditioning/

  2. an electret microphone (the panasonic wm-61a) wired up like this:

    http://www.chris3000.com/archive/breath-sensor/

  3. a temperature sensor (TMP36):
    Temperature sensor tutorial - Using the TMP36 / LM35

This is the code I used just to see if I was getting any input.

#define LED 13
#define MIC 1
#define POT 2
int val = 0;
int thresh = 0;

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(MIC, OUTPUT);
  pinMode(POT, INPUT);
}
void loop() {
  thresh = analogRead(POT);
  val = analogRead(0);
  if (val > thresh) { 
  digitalWrite(LED, HIGH);
  digitalWrite(MIC, HIGH);
  }
  delay(10);
  digitalWrite(LED, LOW);
  digitalWrite(MIC, LOW);
 
}

With the piezo I got something if I tapped/thumped it, but nothing at all from breathing. Even loudly. I had originally tested a piezo because of this:

http://www.dtic.upf.edu/~jlozano/interfaces/blow_sensor.html

I didn't test it with the schematic he has posted, but when using a piezo with some signal conditioning, it didn't seem fit for purpose.

With the microphone I got nothing at all happening. I'm assuming this is because the microphone wasn't getting enough power to produce audio. I just had the mic capsule plugged directly into the breadboard and wired up with 5v only.

The temperature sensor seemed to work OK in that if I breathed on it, the values went up, but they didn't go down quickly enough, and I assume would sort of get 'stuck' after a certain point of breathing on it as my breath wouldn't get it any hotter.

I briefly looked at something like the Yamaha MIDI breath sensor:
http://www.dv247.com/computer-hardware/yamaha-bc3a-breath-controller-headset--2970
But I don't need (or want) to have my lips sealed around the sensor the whole time. But simply to breath/exhale on it.

So what's the best way to get breath data into the Arduino?

(Thank you for reading)

2

Go with the condensor mic - only wire it up correctly.

"With the microphone I got nothing at all happening. I'm assuming this is because the microphone wasn't getting enough power to produce audio. I just had the mic capsule plugged directly into the breadboard and wired up with 5v only. "

I use them to record music, but wired up like this, feeding an amplifier, for output centered around ground. You'll probably want to have the output go across two 100K resisters (+5V-100k-100K-Gnd, connect mic & arduino to the middle junction) for steady 2.5V output that can go 0-5V.
(I should try that - heading off to a fencing tournament soon tho).

3

This one.

4

I like the balloon at the end of the tube ...

5

The capsule you linked to appears to be a three conductor type. Mine is two conductors.

And with your setup, you have the capsule wired up to a 9v. So you're saying take the actual audio output from a working condensor setup, and run that into the 100k/100k setup you described?

CrossRoads:
Go with the condensor mic - only wire it up correctly.

"With the microphone I got nothing at all happening. I'm assuming this is because the microphone wasn't getting enough power to produce audio. I just had the mic capsule plugged directly into the breadboard and wired up with 5v only. "

I use them to record music, but wired up like this, feeding an amplifier, for output centered around ground. You'll probably want to have the output go across two 100K resisters (+5V-100k-100K-Gnd, connect mic & arduino to the middle junction) for steady 2.5V output that can go 0-5V.
(I should try that - heading off to a fencing tournament soon tho).

6

Also, would that mean that my input values will be between 500ish and 0/1000? So I would only have half of the resolution (though not terribly important in this setup).

That's if I'm understanding you right.

7

You have to amplify signal from the mic, at least 100x.
Look at sparkfun web site, they have electret mic breadboard with OPA on it.
Other option I could think, is temperature sensor that initially worm up by nearby resistor,
so when you blow on it, it getting colder. Depends on "initial" temperature (100 - 150 C degree)
it could be very sensitive.

8

Oh yeah, I forgot about the spark fun mic/amp. Go with that one.

9

If you goal is to have the brightness depend on how hard you blow on the sensor, and you don't mind having to put your lips around a tube, to blow into it effectively, a good answer would be...

$25 for a device that you wire to 5v, GND and an analog input. To quote from site....

The currently stocked MPXV700xDP sensors are five volt sensors and the outputs float at 2.5 volts, with no pressure on the input. Suction will cause the sensor to output lower voltages, pressure will cause it to output higher voltages.

10

guyton:
Hi forum.

So what's the best way to get breath data into the Arduino?

Hey Guyton,
I am facing the same problem and I am curious to find what was your "final" solution.
Can you post it, with a schematic for the breath-data-into-Arduino portion if possible (I am also a newbie.....)

Thanks!