| 摘要 |
PROBLEM TO BE SOLVED: To maintain a step-up voltage when a battery voltage is lowered. SOLUTION: A transistor 48 is turned ON, OFF to generate a counterelectromotive force in a coil 42, and a high voltage is charged in a capacitor 46 through a Zener diode 44. When a voltage drop of a battery is detected, a switch 52 is closed, a transistor 50 is connected in parallel with the transistor 48, and the two transistors are simultaneously turned ON, OFF. It is suitable to maintain a drive voltage of the transistor 48 by utilizing another constant voltage source.
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