This is a four-wire PWM fan speed controller. It can only control 12V four-wire fans that support PWM speed regulation. For example, many 12V four-wire chassis or CPU fans cannot control 2-3-wire fans. If the speed of the fan changes and the direction of adjustment is opposite, it means that the fan is a reverse-sequence fan, and the (PF) setting point needs to be short-circuited with solder, and the power must be turned off before operation to avoid damage! The short-circuited PWM signal changes in the reverse direction with the adjustment, and the reverse-sequence fan can realize forward adjustment. Pay attention to the positive and negative poles and the power supply voltage. After the power supply fan is connected, it can be used. The potentiometer is turned off counterclockwise to the end, and the clockwise end is the maximum output. A separate small adjustable resistor (starting speed adjustment) on the board is used to adjust the