| 摘要 |
PURPOSE:To enable the large increase or decrease of the width of an inductance during the application of a voltage by controlling the attachment or detachment of a cylinder made of nonmagnetic conductive material into or from a coil and controlling the extension or shrinkage of the coil. CONSTITUTION:A terminal board 2 made of insulator on which a power distribution board or the like is mounted is provided at one end of an insulating cylinder 1. An insulating ring 3 is engaged on the outer periphery of the cylinder 1, and can be laterally moved on the cylinder 1. In this case, the ring 3 can be locked with a screw or the like. A coil 4 is secured at one end to the terminal board 2, and is secured at the other to the ring 3. An aluminum pipe 5 is so mounted so to be laterally move along the inner peripheral surface of the cylinder 1. |
