| 摘要 |
PURPOSE:To easily control power and prevent noise from being generated, by thinning-out-controlling commercial power voltage with a zero-cross trigger. CONSTITUTION:From a zero volt pulse generating circuit 3, pulse train synchronized with the zero-cross point of a commercial power source is generated. A voltage detector 4 is used to detect the voltage across a bidirectional thyristor 2. A comparator 5 compares the output of the voltage detector 4 with a reference voltage 6, and the output of the comparator 5 is directed to one side for input at the input terminal of a NAND gate 7. The output of the zero volt pulse generating circuit 3 is applied to the other side of the input terminal. When the input of a motor fan 1 is heightened, then the output of the voltage detector 4 is lowered, and when the output comes to the value of the reference voltage 6 or less, then the output of the comparator 5 gets lower and the output of the NAND gate 7 gets higher, and the bidirectional thyristor 2 is turned OFF. In other words, to the motor fan 1, the voltage of thinned-out commercial power voltage is applied and controlled. |
