i have seen
http://www.runyourcaronwater.com/................its realtivley simple we did it on one of my automotive courses at camden county college. With a jump box. You put two dissimaler metals, one negative, one postive into a bucket of water. Then two test tubes upisde down near each negative and postive end. When all the water is gone one test tube will be filled with hydrogen gas and the other oxygen.
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Motorcycle tires