"220V Cooling Fan" Differences and DC electric fan. The former power of communication, alternating positive and negative power supply voltage, unlike the DC fan power supply voltage is fixed, it is necessary to rely on circuit control, two sets of coils in turn makes the job competence are not the same magnetic field occur. AC fan supply frequency is fixed, the pole change speed silicon occurs by power frequency resolution, the higher the frequency, the faster the switching magnetic field, the faster the speed will theoretically like "220V Cooling Fan" the more speed the more the number of poles fast same principle. However, the frequency can not be too fast, too fast to form activated difficult. Conductor through the current, the magnetic field around will occur, if this conductor is placed in another fixed magnetic field, then the attraction or repulsion occurs, creating objects move. In the "220V Cooling Fan" internal blades, attached to a pre-filled with the magnetic rubber magnets. Surrounded by silicon, the axis portion surrounded by two coils, and the use of the Hall sensor component as a synchronous detection device, control a group of circuit which makes surround the axis of the two coils turns the job.