| 摘要 |
PURPOSE:To increase the range of variation and to control a phase controlling circuit safely against an electric shock by controlling the gate of an FET provided in a charging circuit of a capacitor of a gate circuit. CONSTITUTION:When a power source 1 is in positive cycle, a voltage VGS applied between the gate and the source of an FET6 becomes as the equation (1), where R7, R8, R10 represent the resistances of resistors 6, 8, 10, and the parallel resistance value of the resistors 7 and 10 is R7//R10. When the power source 1 is in negative cycle, the voltage VGD between the gate and the drain of th FET6 becomes as the equations (2), (3). Accordingly, the voltage varies when the variable resistor 10 varies, thereby enabling to largely vary the current flowing through the FET6. When the resistance values of the resistors 7, 8 are increased, the electric shock current of human body via wires 9 can be reduced. |
