What are the functions of the three wires and the four wires of the cooling fan?

With the continuous expansion of factories, it is necessary to purchase various types of mechanical equipment, but due to work or environmental reasons, many equipment must operate in harsh environments such as high temperature, heavy dust, and humid air. For this reason, many industries need applications Go to the cooling fan to reduce the working environment temperature of the equipment and extend its service life. However, as the demand for cooling fans increases, people’s requirements for them are getting higher and higher. Now there are three-wire and four-wire cooling fans on the market. The three-wire and four-wire cooling fans have What's the function? 　　 The three wires and the four wires in the cooling fan are the two added signals, the speed regulator signal line or the temperature measurement signal line. The three wires are red, yellow and black, which represent 5V, 12V, and ground. However, it can work only by connecting the red and black wires. Connecting 5V turns fast, and connecting 12 turns fast. And the heat dissipation fan manufacturer also told us that the temperature measurement signal line, the manual speed controller is actually a variable resistor, when the resistance is adjusted to the minimum (or shorted with a jumper), the speed of the cooling fan is the lowest when the resistance is the largest (Or remove the jumper) the AC fan runs at full speed. There are two speed regulators in the accessories of the cooling fan. Just put the thermistor between the cooling fan and the heat sink, and then unplug the yellow signal wire jumper on the cooling fan and the yellow signal wire of the cooling fan. The connection of the plug and the temperature measurement signal line is complete, which actually looks relatively simple.　　 The other is the speed regulator signal line, which is connected to the temperature signal. Generally, the thermistor is used as the temperature sensor for temperature sampling. The temperature change causes the resistance value of the thermistor to change. The speed measurement signal of the cooling fan is generally output from a three-lead plug. The yellow and black of the three leads are +12V power and ground respectively. The speed signal output from the cooling fan circuit is usually in the form of pulses. Each wave head means that the cooling fan has rotated once. In this case, the signal can be directly provided to the host through the data bus for display, and work in this form .