At present, there are two types of fan monitoring methods: alarm sensors and speed sensors. The alarm sensor can give an alarm signal when the fan speed is lower than a certain threshold value, and the speed signal output can realize real-time monitoring of the fan speed. Obviously, the larger the air volume of the cooling fan, the higher its heat dissipation capacity. This is because the heat capacity ratio of air is certain. The larger the air volume, that is, more air per unit time, can take away more heat. Of course, under the same air volume, the heat dissipation effect is related to the flow mode of the wind.

　    The alarm signal output from the fan circuit has two states: "high level" and "low level". The meanings of the two levels generally follow the positive logic system. The high level indicates "fault" and the low level indicates "normal".

　    The speed signal output from the fan circuit is usually in the form of pulses, and each wave head indicates that the fan has rotated one circle. Such a signal can be directly provided to the host through the data bus for display. The speed signal output by some fans is not the actual speed of the fan, but a multiple of the speed. For example, 2, 4 or 6 pulses are generated per rotation, which must be processed to form a signal reflecting the actual speed of the fan. If you want to distinguish whether the fan speed is the actual speed or a multiple, you can use a tachometer to measure the actual speed and then compare it with the displayed data. 

　    The fan speed signal is usually output from a three-pin plug. The yellow and black leads are +12V power and ground respectively, and the other color is the speed signal output line. It should be noted that the third lead of some three-pin fans is not the speed signal output line, but the speed control signal line, through which the speed control signal is input to the fan motor. 

　    Shenzhen Huaxinrong Plastic Electronics Co., Ltd. (a subsidiary of Dongweifeng) was established in 2008. It mainly produces and develops a series of products such as AC and DC cooling fans and DC motors. In today's rapidly changing modern technology, all colleagues of Dongweifeng will continue to dedicate high-quality products and services to our customers, and strive to become an indispensable partner for every customer to achieve success.

        Shenzhen Dongweifeng Electronic Technology Co., Ltd. was established in 1991. It is a national high-tech enterprise. It has now developed into a professional supplier of cooling solutions and products for computers, electronics, etc. The company has successfully passed ISO9001:2000 quality system certification, ISO14001:2004 environmental system certification and UL. TUV. CE product certification. As a national key high-tech enterprise focusing on R&D, manufacturing and sales, it has formed three pillar industries: computer electronic radiators, cooling fans; LED lighting, outdoor landscape lighting engineering lighting; and architectural decorative panels.