| 摘要 |
PURPOSE:To prevent the circuit from being influenced by a power source voltage change after the starting by causing a starting current to flow at the first constant voltage element at the initial time of the starting by the function of the second constant voltage element and a switching element and thereafter, interrupting that the starting current flows at the first constant voltage element. CONSTITUTION:Since a starting current flows through a starting resistance 8 to the second constant voltage element 9 at the initial time of the starting, the terminal voltage of the second constant voltage element 9 rises and a switching transistor 10 is biased in the forward direction. As the result, the starting current is supplied through the base emitter of the switching transistor 10 to the first constant voltage element 1. When the terminal voltage of the first constant voltage element 1 rises up to Vz-VBE (provided that the terminal voltage of the second constant voltage element 9), the switching transistor 10 comes to be a reverse bias, is interrupted and the starting current is not supplied to the first constant voltage element 1. Thus, even when a power source voltage Vcc is changed, the output voltage of an output terminal 6 is not influenced by the change of the power source voltage Vcc.
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