"220V Cooling Fan" infrared digital tachometer is a non-contact, optical sensing of speed measuring instruments. It consists of a light source, optical disk, a photodiode detector amplifier with digital display devices and other components. "220V Cooling Fan" Optical disc rotates together with the shaft, the photodiode photoelectric plate transmitted optical signals into electrical signals, and then by frequency count pulses, you can read the speed of the rotating shaft on a display unit. The "220V Cooling Fan" measuring instrument is the use of infrared tape rebound principle to measure the value of reliability is relatively high. Then the author of this power data measured at different working conditions.