by ohneschuh @ instructables.com:
Capacitive sensors are an elegant way to control an Arduino using the Capacitive Sensing Library. But the sensitivity and error tolerance depend strongly on the hardware (sensor) design. I found a design guideline here and tested different setups which mostly work well if the Arduino was powered by battery. But the sensor signal changes dramatically if I connect the Arduino to a power supply.
Actually I found a design for five (and more) sensors which works well powered with battery and power supply.
Capacitive Sensor Design – [Link]
Toumas decided to code his own capacitive touch sensors based on a closed source Atmel example where a single ADC pin is used for capacitive sensing. He reverse engineered it, and documented his results: [via]
I’ve been thinking of a project that needs a little bit more elegant user interface than your usual push buttons. Partly inspired by a video blog on Dave Jones’ EEVblog, I decided to look into capacitive touch buttons. The big issue unfortunately for me was that you usually need a separate chip for capacitive touch sensing. With some tricks, you can however use a normal microcontroller to do the job. Even using only a single pin and resistor.
Capacitive touch sensing with a single ADC pin – [Link]
If you ever wanted to integrate touch sensitivity into your project, this board could just do the trick. It’s a capacitive touch sensor. These sensors are used in our everyday consumer electronics like notebook trackpads, video game consoles, touchscreens…just to name a few.
Capacitive Touch Sensor on Arduino – [Link]
This project is a capacitive touch sensing keypad with 6 buttons based on the QProx QT160 charge transfer proximity sensor chip. When a button is pressed the circuit provides some visual feedback, a clicking noise and translate the output into an i2c bus signal. Special mylar capacitors are required for it to work properly. Check details on the link below.
6-Button Capacitive Touch Sensing Keypad – [Link]
In the past, NerdKits has shown you a 14MHz freezer, a pseudo-random Valentine’s Day card, and a USB-connected digital bathroom scale — so why not a haunted candy bowl? For this special spooky Halloween project, we’ve put together a Halloween Jack-O-Lantern that glows when you reach your hand in. The technology used for our proximity sensor is the same technology that is used in laptop trackpads and smartphone touch screens, just implemented with a somewhat more MacGyver twist. We use two sheets of aluminum foil to create a capacitive proximity sensor. The sensor trips when a hand is near, and lights go on to surprise and scare the unsuspecting trick-or-treater!
Capacitive Touch Sensor: Learn Electronics with a Spooky Halloween Project – [Link]