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I am trying to create a DIY linear generator like http://www.creative-science.org.uk/gensimple1.html. However, I am wondering if this design i thought of will work or not or give more voltage or not.

Basically, instead of a solid coin-like NIB magnet like the one in website, i will be using a hollow tube shape NIB magnet instead (please refer to image http://www.filefactory.com/file/ah2f2f4/n/Scan10085_JPG ). I am wondering if this design, giving more surface area and thus more change in flux (?) will allow higher voltages to be produced. Because i need around 1.2 V to light an infrared LED for 1/30th of a second and want to minimize number of windings.

Thank you very much.