| 摘要 |
PURPOSE:To accurately start a blower motor against dynamic friction force in a low setting state without sensing a rush of air by applying the base voltage only for a preset period of time corresponding to a high rotational speed. CONSTITUTION:When an off/low/high selection switch 6 is pressed, a relay 4 for low speed rotation is turned on through a Schmitt trigger circuit 7 and a counter 8 via a transistor T1. Simultaneously with this, the Q1 output is differentiated by a capacitor 9 and a resistor 10 and waveform-shaped by Schmitt trigger circuits 12 and 13. The Q1 output issues a logic value (1) only for a preset period of time and operates a relay 5 for high speed rotation through an OR circuit 14 and a transistor T2 for a specified period of time. As a result, when a blower motor is normally set low, noise can be reduced fully and the blower motor can accurately be started in a low setting state even at low temperatures.
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