| 摘要 |
PURPOSE:To reduce the number of high withstand voltage elements by temporarily converting an AC input of a width to a DC constant low voltage, and supplying power to a main power source circuit and a self-excited auxiliary power source. CONSTITUTION:A DC voltage from an input terminal 40 is opened and closed by switching means 23, thus smoothed by smoothing means 24-26 to obtain a DC output 41. The means 23 is controlled by initial starting means 28 at power source energizing time, and control means 29 for applying a switching signal for maintaining the output 41 constant. The auxiliary power source is formed of a self-excited transformer 30 and a transistor 31, and the collector oscillation signal of the transistor 31 is applied to the means 29 to the original switching signal. Thus, since the auxiliary power source is temporarily set to a low constant voltage by the means 23 and the DC output 41 is applied and converted, the number of high withstand voltage elements can be reduced. |
