POWER SOURCE CIRCUIT FOR CHARGE-AC POWER TOOL

摘要

PURPOSE:To prevent overheat of a tool due to continuous use and to improve safety by measuring the temperature of a heating member in a load side circuit and controlling the output current corresponding to the measurement results. CONSTITUTION:A PWM control circuit 14 performs feedback control of ON/OFF duty of a switching circuit 4 such that the output current or voltage from a rectifier circuit 6 will be constant based on output signals from a constant current circuit 12 and a constant voltage circuit 13. A constant temperature control circuit 16 measures the temperature of a heating member at the load side and provides an output corresponding to the measurement to the constant current circuit 12. The constant current circuit 12 controls the PWM control circuit 14 corresponding to the measurement and maintains the temperature of the load side heating member at an approximately constant level.