| 摘要 |
PURPOSE:To protect this device when making and breaking a power source, by delaying the rise of the output voltage of an auxiliary power source circuit when a power source switch is in ON, and by hastening the fall of the output voltage when the switch is in OFF. CONSTITUTION:An auxiliary power source circuit 40' is connected to a control circuit 60 for switching a switching element 61 of an alternating current-direct current converter ON-OFF, and a switching circuit 50 consisting of a Zener diode 51 and transistors 54, 57 is connected to a preceding stage of the circuit 40'. Thus, if main circuit voltage Vi exceeds the Zener voltage of the diode 51 when a power source switch 2 is in ON, the transistor 57 is in OFF, and the output voltage V2 of the auxiliary power source 40' rises; when the switch 2 is in OFF, the action of the switching circuit 50 is inverted, and the output voltage V2 falls by the electric charge of a condenser 43. Consequently, the burden of the transistor 61 in the case when making and breaking the switch 2 can be lightened because the rise of the output voltage V2 is hastened. |
