Capacitive touch wheels using only 3 analog pins!
NOTE: Due to pin hardware limitations, A6 and A7 don't work with the method used.
The TouchWheel library scans 3 touch pads, when put in a circle this allows for a touch wheel that can detect clockwise and counterclockwise finger movement. The 3 pads can be repeated any number of times for higher resolution touch wheels. 9 and 12 pad wheels with a 1.7" diameter work very well.
The TouchSlider library scans 2 touch pads which are interwoven so that the surface area trades off between each pad over the slider area.