| 摘要 |
A magnet device with double fixing positions for changing the magnetic circu it is provided, and includes an external housing whose inner edge is fitted wit h a coil The inside of the external housing includes a space for the axial movement of an iron core. The external housing and a positioning cover at th e opening end of the housing are made of metal with excellent magnetic conductivity. The iron core is connected to a permanent magnet which is fixe d at the inner side of the positioning cover. A drive circuit is provided whereby a positive impulse voltage will be output and the electrical energy is saved i n a capacitor when the power is switched on. A discharge current is created to output a negative impulse voltage after the power is switched off, and the positive and the negative impulse voltages serve to make the coil change the direction of the magnetic force by the excitation process, so that a push force or a pull force on the iron core will be created for movement thereof. The permanent magnet will be forced to change the magnetic circuit and the iron core under ordinary circumstances will be kept at the pre-arranged position without continuous waste of electricity. Not only can this save electric energy, but it will avoid creating an over-heated state or a short circuit, so that a dangerous situation is prevented and the useful life of the device is extended.
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