| 摘要 |
PURPOSE:To reduce the oscillating sound when a power source is turned ON by connecting a soft starting circuit formed of resistors, a capacitor and diodes with the output side, and preventing the voltage immediately after the power source is turned ON from abruptly rising. CONSTITUTION:A soft starting circuit having resistors 2, 3, 4, diodes 12, 13 and a capacitor 15 is connected with an output side. When a power source is turned ON, currents flowed through a photodiode 17, the resistor 4 and the diode 13 and through the resistor 2 charge the capacitor 15 when an output voltage V0 is rising. At this time, when the light emitting amount of the photodiode 17 is large, the output of a photoreceptor 18 controls a controller 9, the ON width of a transistor 8 is reduced to decrease the energy transmission to the secondary side. Thus, the abrupt rise of the output voltage immediately after the power source is turned On is suppressed to reduce the oscillating sound. |
