| 摘要 |
PURPOSE: A power on/off controlling method is provided to obtain a serial power in a serial AC power without using a power transformer and protect all circuits in respect to an impulsive overcurrent generated from the input AC power or a load. CONSTITUTION: When a switch is short-circuited, a triac 1 is closed and an AC power is inputted to A1 point of a triac 2, then a voltage is applied to the triac 2. If A point is positive and B point is negative, a zener diode(ZD1) is closed to form a uniform voltage to a zener diode(ZD2). The triac 2 is closed and a current corresponding to a breakover current of the triac 2 is flowed to a DC power rectifying circuit. When A point is negative and B point is positive, a voltage division to a parallel voltage is performed to protect a circuit from an overvoltage. When the switch is open, the current does not flow to a load with a sufficient amount to operate the load. DC power can be obtained even in this state according to operative principles of the triac 2, the zener diode(ZD1,ZD2) and capacitors(C2,C3).
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