| 摘要 |
PURPOSE:To shorten an opening time by completing the control of a current flowed to a flywheel diode in a self-circuit. CONSTITUTION:A series circuit of the coil 3 of an electromagnet and a transistor (Tr) is connected between terminals P and N of a DC power source. When Tr2 is turned OFF, a current is flowed in a circuit of the coil 3, a capacitor 9, a resistor 8, a Tr4, a flywheel diode 5 and the coil 3 by a counterelectromotive force generated in the coil 3. Thus, the capacitor 9 is charged. A base current is flowed to the Tr4 by the charging current to turn ON the Tr4, and the current of the coil 3 is flowed in a circuit of the Tr4, the diode 5 and the coil 3. Then, when the Tr2 is turned ON, the coil current is flowed toward the Tr2 to eliminate the counterelectromotive force. Thus, the base current to the Tr4 is also eliminated, and the Tr4 is turned OFF. Simultaneously, the charge stored in the capacitor 9 is discharged in a circuit of a resistor 6, a diode 7, a resistor 8 and the capacitor 9. This operation is repeated, even if the Tr2 is intermittently interrupted, the coil current is continuously flowed. |
