| 摘要 |
PURPOSE:To use a driving power supply eficiently, by floating a constant voltage circuit supplying the power supply to a detection circuit, when the output of the detection circuit is present. CONSTITUTION:When an output of a detection circuit S becomes from high to low level, a transistor (TR)Q2 turns off and a constant voltage circuit 3 is in floating state While the instantaneous value of the output of a rectifier 9 is small, a Zener diode Z2 is nonconductive, the thyristor 2 turns off, a capacitor C1 is charged with a voltage at a point D during this period, and a power supply is applied to the detection circuit S. When an instantaneous value is greater, the diode Z2 turns on and the thyristor 2 turns on, allowing to lower the voltage at point F. when the voltage of the capacitor C1 decreases, the diode Z2 turns off and the capacitor C1 is again charged. |
