Hoodie Power

In the spirit of sustainable energy, fellow ITP student Gilad Lotan and I worked on a circuit that would enable the wearer of a hooded sweatshirt to light small embedded lights, using the movent of the string through the hood. The concept behind this comes from that of a "shake powered" flashlight, which uses a solenoid like motor coil and a magnet to pass back and forth inside of it. The idea is to transfer the kinetic movement of a magnetic field through the coil into an electrical signal which is can then be used for a light.

For the prototype that we built, Gilad and I took a black plastic tube, and made coils around the outside using enamel coated wire. Below is an image of us making one of the coils using an electric drill.





We experimented with several different guages of enamel coated wire, and eventually settled on a wire that was much thinner than the wire in this photograph, the only reason we didn't start with it is because I had assumed that we needed continuity across the coil, but it turned out that it's fine without continuity to induce electrical current. That concept alone was a hard, but rather useful lesson in the flow of electricity. By stacking several coils, connected in paralell, we were able to up the "juice" to an acceptable level. The circuit itself is just the coils, each attatched to a diode bridge (as shown on the previous post) and then into a capacitor. We also have several groupings of 5 strong magnets in various places on a string that runs through the center of the tube. As the string is pulled back and forth, the coils induce an alternating electromagnetic current, which is then changed to a DC current stored as a charge in the capacitor.

Gilad has included a diagram of how the coil induces current on his BLOG, as well as the figures on the millivolts we were harvesting through the transfer of energy. Also there is a great video of our early prototype in action!