Kinetic Hula Hoops? They don’t work. There is lots of kinetic energy rolling around in a hoop as you spin it, twirl it, trick it, and work your body to keep it going. Unfortunately, this is a difficult energy to harness. It seems like the 30lb force magnet does not get enough force to travel fast enough through the wire coils to conduct the electromagnetic energy needed to power the 5mm LEDs. The centrifugal force tends to hold the magnet in place rather than rotating it quickly around the hoop. To harness the energy I would need spikes jutting from the outside for the magnet to travel up, but this would be unsightly and cumbersome for the hooper.
I was excited to write this article once the prototype was finished and proved to be viable; however, it failed. There are many articles on how to do something that does work. There are very few that tell you how to do something that does not. This is my eHowNot. Why? Because maybe you can tell me how to fix it. It is also a warning to others who decide to embark upon this venture. There are no articles online with the tags “kinetic” or “friction powered” combined with “hula hoop.” At first I thought, “Yes! I can be the first.” A month into the design and creation made me realize why.
This was the final implementation of my design including all of the experimentation that went along with it. Learn from my mistakes. And if you find a working solution, please let me know. I would also appreciate any suggestions on improvement.
I decided upon two tubes: an inner tube with the wire coils wrapped around it and the magnet would travel inside of that one. The outer tube would be for hooping comfort with holes cut into it for 5mm LEDs and their reflective housings. I chose the LED size of 5mm because it would take the lowest amount of energy to power them. The reflective housings were to strengthen their luminescence. The magnet was a 30lb force cylindrical 1″ x 7/16″ neodymium. This was the strongest at that size that I could find. The size was important because it had to fit inside the 1/2″ inner tube and be unrestricted in the travel around the hoop. I also used a spherical 7/16″ ball bearing magnet with considerably less pull. Both were tested in a foot long piece of the inner tube with the wire coiled 750 times in a 1.5″ section. This test proved that it could power the LEDs with enough force. The spherical ones were less effective than the cylinders and the more cylinders, the less friction necessary to power the light.
The ??? gauge copper enameled wire was wrapped 1500 times within a 2.5″ area on the final product. In one case it was wrapped 1370 because the wire broke in the middle of winding. In another case it was wrapped 2000 times for experimental purposes. I should have wrapped one 1000 times and one at 750, but I did not. When I feel like working on it once again I am sure these will be problem solving techniques I address. Both the LED leads and the ends of the wire attached to them were filed with a fingernail file to scrape any protective residue from them to ensure a sound connection. The conductivity was also tested with an ohm meter from the LED leads and the ends of the solder.
Each unit was treated as an individual circuit powered by one magnet. Two spherical magnets attached to either end of one cylinder were attempted first. The final problem I encountered in the structure was to connect the inner tube inside the outer tube’s connector piece. It was not a solid fit, so I resolved to put an assist on the cylinder magnet with the spherical magnets. To compensate for either way the hoop might be spinning, the spheres were attached to both sides. Also tried were a single ball, multiple balls, only the cylinder and two cylinders. My next trials will be the same combinations with grease on the surfaces of them.
The LEDs were secured using a nonconductive cement glue around the edges of the housing. I had no problems keeping them fastened despite much roughhousing with the tubes. They were dropped, pulled, and thrown in the name of testing and not necessarily frustration.
See? This was helpful. I found numerous new experimentation methods just by talking about it with someone to maybe make it actually work. The greasing is the prize, I think. First, I will try wrapping the magnet in wax paper like we used to do with slides in elementary school. This will keep it from getting dirty inside the seals. The other test will need to be the coiling amount and the span of the area. These will be done on a separate piece like the initial tests before doing the entire hoop. Truthfully, though, I believe it is the speed of the magnet that needs to be addressed.
Again, comments would be appreciated.
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