| 摘要 |
PURPOSE:To obtain a ventilation fan control device capable of making a relatively large current flow through a transistor of a flywheel circuit, controllable with a large load, and with lesstrouble even under a lightning surge. CONSTITUTION:A device comprises a switching circuit 3 connected in series between an AC power supply 1 and a ventilating fan motor 2 so as to perform both positive/negative switchings by a frequency higher than the power supply frequency, pair of flywheel transistors 11, 16 connected in parallel to the ventilation fan motor 2 to perform both positive/negative flywheelings and a voltage comparator 36 for actuating the switching circuit 3. Through a base of each transistor 11, 16, a continuous current is allowed to flow from the AC power supply 1 respectively alternately by polarity of the AC power supply 1 regardless of switching action of the switching circuit 3. |
