In this instructable you will learn:
* How to use the Cap Sense library to make Arduino responsive to touch
* How adding a Wave Shield (and some root vegetables), you can make a "Beetbox"
Step 1: You Will Need
* Arduino UNO
* A 4.7M Ohm resistor (or a value similar to that) (one for each sense channel)
* Breadboard for wiring up e.g. (http://goo.gl/1E1iI)
* Some Wires
For an initial experiment to show how touch sensing works:
* An LED
* a 560 Ohm resistor
For the "Beetbox" part:
* Some Root Vegetables (such as a Beet)
* An Adafruit Wave Shield as shown http://goo.gl/KUUZz
* The WaveHC library for Arduino (http://www.ladyada.net/make/waveshield/download.html)
Step 2: The Principles of Capacitive Touch Sensing
To start we'll implement one touch sense channel and activate an LED when Arduino senses touch.
Wire up the circuit as shown in the Fritzing diagrams and photo's.
Get and Install the Capacitive Sense library for Arduino from here: http://goo.gl/EpSX0
Step 3: Here's How the Capacitor Sense Works
The measured delay is proportional to the Resistor value R and the Capacitance C. i.e. Delay = R*C
(strictly speaking there's a scaling factor too depending on the voltage level you're measuring from, but that's just a detail for us).
The Capacitance on the sensor varies as you bring your finger close to the sensor and as you touch it. Touching the sensor gives you the largest capacitance and the longest delay. In order to make the delay large enough to be detected by Arduino you need a large resistor e.g. 4.7Meg Ohms.