Picture of Arduino Air Cap-Sense Piano
I recently got my shipment of 10 buzzers I ordered about a month ago, so as soon as I got them I was eager to make something fun with them, so I looked around a bit and searched for what to do with them, and by spending some time on www.arduino,cc and posting lots of questions on the forums, I figured out what I am going to make.

I decided to make an air piano which is based upon cap-sense and the arduino.

  1.     Aluminum tape or aluminum foil
  2.     Some wires
  3.     8 10M Ohm resistors
  4.     Piezo buzzer
  5.     Arduino
  6.     9V battery or USB cable

Basically, there are square pieces of aluminum tape stuck onto a thick card which is attached to a jumper cable and a resistor, 8 replicas of this are made, then all the other ends of the resistors are attached together and to pin3 of the arduino, this will act as the common base pin for all the sensors. The resistor values can be 2M or 10M or 40M Ohm. 2M Ohm will make it so that it only senses when you press on the aluminum tape, 10M Ohm resistor makes it so that your hand can be sensed at a little height of 2-4cm or so and 40M Ohm will sense quite a bit further, but it gets a little messy as if the aluminum tape pieces are too close together then at that height interference occurs therefore other keys might get pressed. If you want to use this 40M Ohm version then you have to make sure to place the aluminum tape pieces a little far away from each other.
I used 10M Ohm for my device and it works perfectly when I wave my hand over the note I want to use.
mhidalgo32 years ago
Hi excelent you project!!! Only want question if I want more inputs is it possible with the arduino UNO, like a real piano
vishalapr (author)  mhidalgo32 years ago
Its possible with most of arduino boards, u can get upto 20 or so outputs on arduino uno and duemilanove and upto 50-60 outputs on mega
If you need more outputs then you can try multiplexing, I didn't try it but it should work (Like an LED cube).
Orngrimm2 years ago
Nice 'ible!

And to answer the question you asked: Resistive sensing uses a different method. Simple put, there are 2 foils (Normally bith transparent) with a bad but existing conductivity stacked over each other with tiny beads sandwitched to keep them apart. If you press on the top-foil it bulges down and connects to the foil below. Since the Foils have a given resistance for each mm in distance, you can read the voltage (analog) and determine how far in in the X and Y-direction you are.
The foils are cheap on dx.com if you want to experiment with them.
vishalapr (author)  Orngrimm2 years ago
Thx :)
ah so the distance between the 2 foils is what does all the sensing in the resistive one?
so it cant be used to have it in air and can only be used to have it when the keys are touched I think...
Correct. Resistive touchpads need a mechanical force for deforming the foil.
See IMAGE for a simple representation of one single dimension.
And if you look at this IMAGE you see both dimensions and also the formulas to calculate the positions... :)
vishalapr (author)  Orngrimm2 years ago
Ok :D I understand now,
It might have been nice to see (hear) the unit in action. If you're going to go to all that trouble to produce a video, I don't think it would have been that much extra effort...LOL
vishalapr (author)  SuperTech-IT2 years ago
Its just that Im horrible at playing it XD so Im trying to learn a simple song first and then Ill make another vid with it in action :)
Thanks for the video. I used to actually make touch sensitive inputs for circuits a way back in the 80's - early 90-s. I am sure you have heard of a Darlington pair...well, if you get up to a darlington quadruplet, touching the base of the first transistor would produce enough signal at the fourth transistor's output, that you could trigger other circuits. It might have been nice to have this back then. Thanks though, I didn't know the Arduino (Atmel) could do this til now. I think it's time to get rid of push-buttons!
vishalapr (author)  SuperTech-IT2 years ago
Yea that would be like super annoying, glad I was able to teach something :)
vishalapr (author)  SuperTech-IT2 years ago
Ok I made a vid :) I kinda managed to play jingle bells but badly lol