Figure 1.17. This is a 3 dimensional drawing of a de arson a vall meter movement. The main features are a permanent magnet and a rotating coil with a pointer attached. First the magnet. This is somewhat like a horseshoe magnet except it is completely circular. It is about two inches in diameter and the hole in the center is about 1 inch in diameter. The magnet is about 3/4 of an inch thick. There is a thin cutout where the poles are. Because of the cutout it is not a complete circle and therefore has two ends. Instead of the ends of the magnet being flat they form a circular hole as if drilled out. At the inside and outside of the ring the poles almost touch. In the center they are about half an inch apart. Now for the coil. It is wound of fine wire and is held by a rectangular piece of some insulating material and a lot of glue. It appears as if the wire is self supporting with nothing holding it together. This rectangular coil is a little less than half an inch wide and 3/4 of an inch long. In the middle of the short side on each end is a short piece of springy metal known as a taught band. The free ends of the band are attached to a support which is in turn attached to the magnet across the opening between the poles, not the big hole in the center. The bands also make electrical connection to the ends of the coil. The coil does not touch the poles of the magnet but is very close to them. The pointer is attached to the coil. The taught bands hold it at a particular position but when a current flows through the wire the coil can rotate on an axis that is parallel to the axes of the holes. It can rotate a little over 100 degrees before the pointer runs into the supporting structure. A nonmagnetic metal plate has a scale printed on it for the pointer to move along. The scale hides the magnet and coil from view. End verbal description. Note. The spelling of de arson a vall has been fractured to make Jaws pronounce it correctly, or as close as I can come. I can't say how it will do with Window Eyes or some screen reader that is not on the market at this writing.
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