Multipole magnets for moving coil instruments - with two concentric ring magnets magnetized radially with a coil in the inter magnet gap

摘要

The simple arrangement of magnets is for use in a moving coil instrument such as a galvanometer. The coil travels in the gap between two ring shaped magnets polarized radially with an odd number (such as five) of pole pairs. The excursion of the coil is limited by this means even if too large a current is passed through it. This represents an advance on previous systems in which overcurrent can result in damage to the coil. The details of the magnets and spool are not given, through a perspective schematic diagram of the system is provided.