When we open the "Mini Air Cooling Fan" look at its internal structure, in accordance with the position of the coil where we can identify them, the circuit board is controlled by an inverter motor with chip DSP function and the set of drive devices, thereby simplifying the "Mini Air Cooling Fan"internal circuit structure, through the chip, we can change the fan speed. Now every household has a computer, one might find a little bit long time to use the computer, the computer will be dropped for no reason. Especially in summer, this situation is particularly serious, in fact, "Mini Air Cooling Fan" indicator dropped when the cat ADSL, LAN my wireless router flashing lights is normal, if their laptops and PCs combined together fall, dropping perhaps 10 minutes longer.