| 摘要 |
PURPOSE:To ensure insulation between a controller and a motor and to prevent mixing of noise, by transmitting a pulse width modulation control signal for controlling voltage to be applied onto the motor through an optical coupling element. CONSTITUTION:A microcomputor 42 transmits a pulse width modulation control signal through a photo-coupler 61 comprising an LED 61a and a photo-transistor 61b to a capacitor 65. Terminal voltage across the capacitor 65 is fed through operational amplifiers 66, 67, 68 to a combustion fan 12. A rotation detecting circuit 80 transmits a pulse signal from a Hall IC arranged in the combustion fan 12 through a photo-coupler 83 comprising a transistor 81 an LED 82 and a photo-transistor 84 to the microcomputor 42. By such arrangement, the controller is protected from being mixed with noise. |
