For my Pleech project, I am trying to develop a low-cost, low-power, easily assembled generator that can be fixed to walls, fan outlets, and other infrastructure in order to generate environmentally friendly electricity for physical-computing graffiti and sentiti applications.

(Note: "sentiti" is my own coinage. It refers to any illicit sensor that can be placed in much that same way as graffiti. Think of it as an unauthorized reading as opposed to an unauthorized writing.)

The simplest method discovered so far, illustrated above, is a Savonius Turbine. This part of a class of Vertical-Axis Wind Turbines (VAWTs) that do not require directing vanes to pick up wind--they can generate using a breeze from any direction. That are less efficient than other designs (see below,) but are regarded in my research as very sturdy and easy to build.

I envision construction of the turbine as follows:

Parts List:
• 3 used CDs
• 1 steel paint can lib
• 1 wooden dowel
• 1 plastic paper-towel holder
• 1 Pringles can (or similar)
• 8 fixed magnets, preferably rare-earth, but any cheap strong magnet should suffice
• Assorted other magnets to affix the Pleech to metal surfaces (optional)
• Glue, epoxy, and/or caulk
• 28-gauge wire for stators
• Drill for making holes and winding stators
• Other electronics for convert AC to DC (TBA)
• 1/8" stereo jack from Radio Shack use as a universal power connector.

The Pringles can would be cut in half lengthwise to produce to half-cylinders. The metal bottom can be discarded. The two halves would be attached, per the diagram, to the used CDs with epoxy or other fixative. The dowel would be run down the center of the CDs to form the basic turbine.

Below the turbine would be the steel paint can lid. Magnets would be attach there and reinforced with glue, etc. They must have their poles alternate, per the diagram. The magnet plate must have a hole punched dead center and then attached to the dowel.

A third CD would receive the stator coils. Each coil would need 300 windings, minimum, which could be down quickly using a drill and some caution. The windings would also need to alternate in direction, per the diagram. The windings are then affixed to the CD. This CD should remain fixed to the bottom of the device.

The turbine with magnet plate and stator plate are then attached to the paper-towel holder. The turbine must spin freely with the holder (using bearings or other yet-to-be-discovered means). The stator plate would remain fixed. The holder would also receive magnets on its surface-mountable part, if the device is to be attached to a ferrous surface.

The leads from the stators would feed into a AC/DC converter and the electricity would be limited by a voltage regulator and keep steady with a smoothing capacitor. Then the DC current would be attached to both ends of the 1/8" jack. This becomes the power source on which other artists can attach their own work using a male 1/8" jack.

Darrieus Turbine Design

As a more efficient alternative, a Darrieus Turbine could be attempted. It replaces the Pringles can with airfoils. These may be constructed using dowels placed near the circumference of the turbine, with plastic sheet wrapped around the dowels to form the leading edge. The trailing edge would then be formed by glue the ends of the sheet together. Two (or even three) of these vanes would then be attached vertically in the turbine. This method is believed to be more efficient, but may also increase the complexity beyond what is necessary.

The above recipe is part of the project itself. It is as important to the success of this project as the physical devices themselves. The ability for people anywhere to create a Pleech using this method is crucial for its construction and dissemination.