| 摘要 |
PURPOSE:To perform the start of the electromagnet and the maintenance of its operation efficiently by providing one electromagnet with two winding parts and by switching the voltage applied to these winding parts by menas of three switching circuits. CONSTITUTION:When a positive control signal is given to an input terminal 10, a transistor Tr6 and also switching transistors Tr4 and 5 are turned to be conductive by the charging current of a capacitor 9. On the winding parts 1a and 1b of the electromagnet 1 is thereby impressed large voltage, whereby the electromagnet 1 is surely started. By the above input of the control signal, Tr15 and also a switching transistor Tr12 are turned to be conductive, although no current flows to the Tr12. Next, after a prescribed time fixed by the time constants of the capacitor 9 and a resister 8 passes, the charging of the capacitor 9 is completed and thereby Tr6, as well as Tr4 and 5, is turned to be nonconductive. At this time, the current flows to Tr12 since it is left conductive, and thus the electromagnet 1 is kept in the state of operation. The voltage impressed on the winding 1 at this time is controlled to be a value smaller than supply voltage Vcc. |
