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61  Using Arduino / Sensors / Increasing sensitivity of a simple resistive touch sensor on: November 12, 2012, 10:29:55 pm
Hello All

I am experimenting with a simple resistive touch sensor, made up by two thumbs tacks. One is connected to +5V and the other to a digital pin with a resistor in parallel to ground as a pull down. I activate the sensor by shortening the two tacks with my finger.
I used a sketch for a Normally OFF momentary push switch.
It took me a while to figure out that it was not working because I was using the recommend (for a switch) 10K pull down resistor (and the fact I am so proud that I figured it out all by myself gives a new meaning to the word "newbie").
I checked the resistance across the shortened tacks (my finger pad resistance) and got about 1.4M.
I replaced the pull down resistor with 2.2M but it did not work too well.
So I replaced with a 4.7M and now it works.
Problem is that you have to cover the two tacks completely in order for it to work. It is not enough to touch them both (with the same finger).
In other words, it is not sensitive enough.
I tried to increase the resistance of the pull down resistor to 6.9M with two resistors in series (2.2 + 4.7) but it does not seem to change much.

Short of licking my fingers or wearing thimbles (one is gross, the other impractical) is there a simple way to increase sensitivity?

Thanks


62  Using Arduino / Audio / Re: ARDUINO + musical instrument shield to make a Keyboard on: November 12, 2012, 07:33:27 am
I found the answer to my own question:
I've been able to use Serial to MIDI converter, which receives midi data from the arduino and sends them directly to the Microsoft GM wawetable synthesizer (or other soft synths), without any additional hardware or software:

http://spikenzielabs.com/SpikenzieLabs/Serial_MIDI.html

Thanks Thot smiley
63  Using Arduino / Audio / Re: Using Arduino Leonardo as MIDI device on: November 12, 2012, 07:23:35 am
Could you use the Serial to Midi Program?

http://spikenzielabs.com/SpikenzieLabs/Serial_MIDI.html
64  Using Arduino / Audio / Re: Serial Midi Converter on: November 11, 2012, 03:13:59 pm

Try replacing that function at the end with this:-
Code:
void MIDI_TX(unsigned char MESSAGE, unsigned char PITCH, unsigned char VELOCITY)
{  
  status = MESSAGE + midichannel;
  Serial.write(status);
  Serial.write(PITCH);
  Serial.write(VELOCITY);
  
}

Grumpy_Mike, you are a genius!   smiley

P.S. After thinking about it, I understand why this works and the previous version doesn't.
But I am puzzled on why did the previous version worked with older board, if it did.
65  Using Arduino / Audio / Re: MIDI Keyboard Encoder - Arduino Piano/Keyboard (question) on: November 07, 2012, 08:26:06 am
....
 Of course, you can do synthesis on PC, there are open source / free software available on-line

Magician, I spent hours looking for something like that for my project but did not find anything satisfactory.
Closer thing I found is VMPK: http://vmpk.sourceforge.net/
What do you recommend? I am looking of something "Arduino friendly".....

Thanks
 
66  Using Arduino / Audio / Re: ARDUINO + musical instrument shield to make a Keyboard on: November 07, 2012, 07:59:31 am
Congratulations Plankton,
  I have a very similar project and I am eager to follow your footsteps. Thank you for posting your results!
Besides being able to generate sounds directly with sparkfun MI interface, or alternatively to it, I want my keyboard to send MIDI data to the computer (PC) with the help of the MIDI library.
I am not quite sure though how to receive the data on the PC side.
In particular, I need to find a program (possibly free, for the time being, while I am experimenting) that receive the MIDI data from the Arduino and plays them right away (with the WIndows GM synth table or something else). So far, no luck.
Do you have any hint or advice to point me the right way?

Thanks

Luca
67  Community / Exhibition / Gallery / Re: Arduino based MIDI controller. on: November 02, 2012, 02:17:50 pm
Very impressive indeed!

I am planning to make a less ambitious MIDI controller to drive  12 pushbuttons (on/off) and 1 analog output (volume)

I would be interested in some details about the multiplexer (hardware, software and model) and the debounce circuits.

Thanks!
68  Using Arduino / General Electronics / Re: Soldering leads to arduino to finish up? on: November 02, 2012, 01:43:31 pm
This may be a bit off topic but I always thought ideally you would transfer your code on a compatible AT microprocessor that you can solder to your final PCB and get rid of all the paraphernalia that make the Arduino board so useful for project development.
According to these websites the transfer is pretty simple.
http://blog.makezine.com/2011/10/10/how-to-shrinkify-your-arduino-projects/
http://hlt.media.mit.edu/?p=1695

The point of those tutorials is to show how to shrinkify your project if you don't need a lot of I/O ports (and you can do with a subset of instructions available for your sketches) but I don't see why you could not do the same with real big AT MCs.

I am not nearly close to "finalize" a project so maybe I am saying something incorrect. Am I?

 smiley-slim
69  Using Arduino / General Electronics / Re: Help: Connecting Flimsy wires to Arduino on: November 02, 2012, 12:31:28 pm
Thanks all for the prompt reply.

I did not think of just stuffing the male end of a header (or maybe an LED or resistor lead) into the socket, but hey if it works.....

Thanks again!
70  Using Arduino / General Electronics / Help: Connecting Flimsy wires to Arduino on: November 02, 2012, 08:39:25 am
VEERY basic question here:

How do you connect flimsy wires, such as for instance those coming out of a piezo element like this: https://www.sparkfun.com/products/10293
so that they make a secure connection with the Arduino I/O pins (or with a solderless breadboard, for that matter) suitable, if need be, for a permanent Arduino device?
If you try to insert them directly in the sockets they bend and the connection is all but secure.

I searched the forum and found similar topics but they all deal with using jumper cable for a breadboard to Arduino connection (which I have).

I was thinking maybe to solder the wire to a male header like this one:
https://www.sparkfun.com/products/553

But it seems to be a tedious job and I am not sure how firm the wire-header connection  will end up to be.

Alternatively to solder them to a piece of solid 22 g (I think) electric wire but I have the same reservations for that as well.

Is there a better way?

Thanks




71  Using Arduino / Sensors / Re: Help: Increasing sensitivity of a Piezo Sensor on: October 31, 2012, 07:54:22 am
DC and Alx,
  Thanks again for the reply.

>>>- a sensitive strain gauge
Did not think about it, it does sound like a good option.
Something like this?:  http://www.digikey.com/product-detail/en/CEA-13-125UN-350/1033-1016-ND/2503707

>>> measuring the change in resistance of a fine heated wire
This is the principle in an hot wire anemometer, right? I was looking at this option:
http://shop.moderndevice.com/products/wind-sensor

>>> having the breath deflect a conductive vane, and measuring the capacitance between that vane and a nearby conductive plate
I am not sure I understand this....  smiley-red

>>> What about one of those small & cheap barometric pressure sensors?
I thought about that, my impression was that a barometric sensor was not fast enough to get the pressure changes you have if you blow in a tube, but I may be wrong
Something like this?:
http://www.karlssonrobotics.com/shop/barometric-pressure-sensor-bmp085-breakout-retired/?gclid=CLrhvrigq7MCFQqe4AodzScAqA

I was also looking, following suggestions given in similar topics, at microphones, to detect the noise you make when blowing, though in an electronic wind instrument you are not suppose to produce sound directly, but to use your breath as a controller for the software to actually play sounds:
Either this: https://www.sparkfun.com/products/9964
or this:  http://robosavvy.com/store/product_info.php/products_id/626/currency/USD
The latter seems to respond better to noise volume than the former, according to posted  comments

Your thoughts are greatly appreciated, thanks.

Luca


72  Using Arduino / Sensors / Re: breath sensor to control LED brightness on: October 30, 2012, 07:23:08 pm
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!

73  Using Arduino / Sensors / Re: Help: Increasing sensitivity of a Piezo Sensor on: October 30, 2012, 06:25:20 pm
Boy, that was FAST!


Do you mean detecting a person breathing lightly, or a blowing hard through a tube?

Something in between. I am trying to build a MIDI breath controller that will respond to blowing in a tube open on two sides, more like a transverse flute than like a clarinet (which is a tube open on one side) and which is the model for commercially available breath controllers (the clarinet, that is).

If I can reliably detect the presence and velocity of the air blown I am half done. The sensor does not have to be linear, as long as the response can be manipulated via software I am fine.

Thanks again

Luca
74  Using Arduino / Sensors / Re: Help: Increasing sensitivity of a Piezo Sensor on: October 30, 2012, 05:16:24 pm
Hey dc42,
    Thank you for the quick reply!

So if I replace my 1 MOhm resistor with, say, a 2 MOhm resistor I will increase its sensitivity (double?).
Will that also protect the Arduino better or the higher the parallel resistor the more the need for the 100 KOhm resistor in series?

And, on a related topic, if a piezo is not ideal for detecting, actually measuring, breath velocity, what other sensor would you recommend?

Thanks

Luca


75  Using Arduino / Sensors / Help: Increasing sensitivity of a Piezo Sensor on: October 29, 2012, 11:14:08 pm
Hello,
  I'm VERY new to Arduino and I am trying to implement a breath sensor using a Piezo and the setup in this tutorial:

http://www.arduino.cc/en/Tutorial/KnockSensor

I simplified the code so that it dumps on the serial monitor any values coming in: 0 if I am not blowing, >0 if I am blowing on the sensor:
The problem is that even if I blow very hard, I am not getting values greater than about 120.

Question: How do I take advantage of the whole resolution of the analog input (1024 if I am not mistaken) so that I get 0 if I am not blowing and 1024 if I am blowing the hardest?

Shall I decrease the value of the resistor in parallel (currently 1 MegaOhm)?
I hesitate just to try because I understand that the piezo can deliver high voltage (up to 90 V or so) and I don't want to fry the Arduino.

TIA

Luca

P.s. The code I am using (modified from the tutorial) is:

___________________
int ledPin = 13;
int knockSensor = 0;               
byte val = 0;
int statePin = LOW;


void setup() {
 pinMode(ledPin, OUTPUT);
 Serial.begin(9600);
}

void loop() {
  val = analogRead(knockSensor);
    Serial.print(val);   
    Serial.write(10);
    Serial.write(13);
  delay(50);  // we have to make a delay to avoid overloading the serial port
}
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