Patent ID: 8853987
Filing Date: 2014-10-07
Classification: B25B,B25F,H03K

Abstract:
1. An electric tool, comprising: an AC motor to which a power is supplied from an AC power supply; and constant voltage generating means for generating a constant voltage from an AC voltage, and using switching means connected in series to the AC motor to carry out a phase control or an antiphase control over the power to be supplied to the AC motor, wherein the switching means includes two transistors which have sources or emitters connected to each other and are disposed in anti-series, the constant voltage generating means includes a series circuit of a first resistor and a diode and a parallel circuit of a capacitor and a Zener diode, one end of the first resistor is connected to a node between the AC power supply and the AC motor, a cathode of the diode is connected to one end of the capacitor and a cathode of the Zener diode, and the other end of the capacitor and an anode of the Zener diode are connected to the sources or the emitters of the two transistors, a control terminal of one transistor of the two transistors is connected to one end of a second resistor, and a control terminal of the other transistor of the two transistors is connected to one end of a third resistor, and a voltage at the other end of the second resistor and a voltage at the other end of the third resistor are switched between a voltage at a node between the series circuit and the parallel circuit and a voltage at the sources or the emitters of the two transistors so that the two transistors are turned ON or OFF.