| 摘要 |
PURPOSE:To prevent the dribble of the driver of an electrically-driven percussing tools by a method wherein only one solenoid excitation is performed without fail in one operation in which an on position is given between the common terminal and the normally opened terminal of a hand-operated switch. CONSTITUTION:A tripple-pole single-direction thyristor 6 repeats a turn-on and a turn-off action in synchronization with the cycle of the Ac current of AC 100V and a gate voltage synchronized to the above is applied to the gate side 14c of the tripple-pole single-direction thyristor 14. Then, after the common terminal 18 and the normally opened terminal 16 of the hand-operated switch 15 are connected, the thyristor 14 is turned on by the next pulse on the side of the gate 14c and a charging current flows to a biexcitation preventing capacitor 19. Through these procedures, a tripple-pole bidirectioned thyristor 3 is turned on and an exciting current flows to a percussing solenoid 2. The charging condition of the capacitor 19 is continuously maintained by blocking a backward current with a diode. Consequently, an off position can be maintained by the thyristor 3 even when the next pulse is applied to the gate side 14c. |
