| 摘要 |
PROBLEM TO BE SOLVED: To output a stable DC voltage even when an AC voltage to be inputted changes.SOLUTION: Since transistors Q1 and Q2 are turned into an off state when a voltage V4 from a rectification circuit 2 is equal to or higher than a threshold voltage Vth, current based on the voltage from the rectification circuit 2 does not flow to an output section 3, thereby generating no voltage at an output section 6. When the voltage from the rectification circuit 2 is lower than the threshold voltage Vth, the transistor Q1 is turned in an on state. In this case, if the threshold voltage Vth is equal to or higher than an output voltage, the transistor Q2 is turned into the on state, thereby causing current based on a voltage V3 from the rectification circuit 2 to flow to the output section 6 to generate a voltage at the output section 6. When the threshold voltage Vth is lower than a voltage obtained by adding a base-emitter voltage of the transistor Q2 to the output voltage, the transistor Q2 is turned into the off state, generating no voltage at the output section 6. |
