| 摘要 |
PURPOSE:To prevent burnout and damage of an electronic device due to dissidence of power supply voltage, by switching the power supply voltage to an optimum voltage of the electronic device automatically. CONSTITUTION:The voltage supplied from a plug 1 is led to a transformer 5 and transformed and rectified. The amplitude of the rectified power supply voltage is detected with a Zener diode and when a power supply voltage higher than the set value is applied, a transistor 7 is made conductive, power is applied to a coil 8 to select a switch contact coupled with a cylinder 9 to a position B. Through this operation, changeover to the voltage circuit of an electronic device 4 matched to the voltage supplied from the power supply is performed to complete normal operation of the device 4. Even if low voltage is applied to a plug 1 when the contact of the switch 11 is changed over to the position B, no failure is caused to the device 4. |
