JP2985047B

PURPOSE: To prevent the excessive supply of a power to a load in a steady state while the load is operable just after power feeding and provide ideal soft starting characteristic. CONSTITUTION: A resistor T1 is connected in parallel to a thermistor TH, a trigger element TG is laid in ON state (a TRIAC TR is in continued state) from just after the input of a power source AC, and an incandescent lamp LP is operated from just after the input of the power source AC. A resistor R2 is connected in series to the thermistor TH, the ON-period of the trigger element TG is shortened in the steady state, and a power is also prevented from being excessively supplied to the incandescent lamp LP. The time constant is regulated by a capacitor C2 and a resistor R3, and the ON-period of the trigger element TG is gently increased to provide ideal soft starting characteristic.