Abstract: Power tools are taught having a motor M1, a tool 1 coupled to the motor M1 via a tool holder 2, at least one light 4 disposed proximal to the tool 1, a switch 6 coupled to the motor M1 and the light 4, the switch 6 being capable of activation by an operator, a power supply 7 coupled to the switch 6, and a timer circuit 3 coupled to the light 4, the switch 6 and the power supply 7. Preferably, activation of the switch 6 causes the motor M1 and the light 4 to operate and the timer circuit 3 causes the light 4 to remain lit for a predetermined amount of time after either (1) the switch 6 has been activated or (2) the switch 6 has been deactivated subsequent to being activated. The timer circuit 3 can be, for example, a RC timer circuit 11 or a microprocessor 15. The light 4 may be an LED. The power supply 7 can be a rechargeable battery Ba.

Abstract: A speed control circuit of a direct current motor comprises a switching regulator IC 10. The switching regulator IC 10 is composed of a reference voltage generator 12 which generates a reference voltage of 5V, a first operational amplifier OP1, a second operational amplifier OP2, a third operational amplifier OP3, a triangular wave generator 14 which generates a triangular wave, and a transistor TR1. The speed control circuit is constructed using a general switching regulator IC; therefore, it is possible to cheaply and readily manufacture the speed control circuit of the direct current motor.

Abstract: Power tools are taught having a motor M1, a tool 1 coupled to the motor M1 via a tool holder 2, at least one light 4 disposed proximal to the tool 1, a switch 6 coupled to the motor M1 and the light 4, the switch 6 being capable of activation by an operator, a power supply 7 coupled to the switch 6, and a timer circuit 3 coupled to the light 4, the switch 6 and the power supply 7. Preferably, activation of the switch 6 causes the motor M1 and the light 4 to operate and the timer circuit 3 causes the light 4 to remain lit for a predetermined amount of time after either (1) the switch 6 has been activated or (2) the switch 6 has been deactivated subsequent to being activated. The timer circuit 3 can be, for example, a RC timer circuit 11 or a microprocessor 15. The light 4 may be an LED. The power supply 7 can be a rechargeable battery Ba.

Abstract: A charging system includes an electric power tool (2) and a charger (1) having internal rechargeable batteries (6) and a controller (9) for monitoring the charge/discharge level of the batteries (6). The electric power tool (2) additionally includes a pair of charge terminals (13a, 14a) for carrying current to charge the batteries (6), a temperature terminal (15a) for outputting to the charger (1) data on the temperature of the batteries, and a data terminal (16a) for outputting to the charger data on the battery charge/discharge level from the controller (9). The charger (1) includes a pair of charge terminals (13b, 14b), a temperature terminal (15b), and a data terminal (16b) that are electrically connected to the corresponding tool terminals when the tool (2) is set on the charger for a charge.

Abstract: An improved charging system for preventing battery deterioration and for accurate indication of the remaining battery charge level includes an electric power tool (2) and a charger (1). The electric power tool (2) is provided with an internal rechargeable batteries (6) and a second controller (9). The charger (1) is provided with circuitry for charging, a microcomputer (19), and discharge circuitry which is comprised of a manually-operated battery refreshing button (25), a discharge relay (23) and a discharge resistor (24). Upon depression of the battery refreshing button (25), the microcomputer (19) causes the batteries (6) of the electric power tool (2) to be charged to a full level and discharged to a predetermined level twice. When the two-cycle operation of full charge and discharge is completed, the second controller (9) of the electric power tool (2) updates the remaining charge level of the batteries (6).