| 摘要 |
PURPOSE: To provide a motor-speed controlling circuit for controlling stably the rotation of a motor by preventing the failure of the commutation of an ignition element in a phase controlling circuit which drives an inductive load while igniting a phase controlling element by the ignition element. CONSTITUTION: When a photo-TRIAC-coupler 7 for ignitions is used as the ignition element of a phase controlling circuit, a Zener diode 10 is connected in series with the photo-TRIAC-coupler 7 for ignitions, as a constant-voltage element for interrupting the gate current of a TRIAC 5 when its phase is inverted. |
