| 摘要 |
PURPOSE:To obtain a sufficiently stable DC output over a wide input range by using a coverter transformer having two primary windings, and swithching those primary windings which are driven in accordance with a low and a high input. CONSTITUTION:A changeover switch circuit 8 connects the base of a transistor (TR) 4b to the output side of a driving circuit 5 normally, and performs a stabilizing function when high inputs are supplied to input terminals 1a and 1b. On the other hand, when the voltage supplied between the input terminals 1a and 1b becomes a low input, a low input detecting circuit 9 operates and the changeover switch circuit 8 performs switching operation to supply a driving signal from the driving circuit 5 to the base of TR4a. At this time, the TR4b requires high dielectric strength, but a TR4a with low dielectric strength is usable, and such a TR has a large DC amplification factor generally and operates with a relatively small base current. |
