The full name of width modulation is: Width , or PWM for short. Because of performance, it is often used as a lamp dimming in a DC loop or a DC motor speed control. This circuit is a motor controller made using the principle of width modulation (PWM). Using this to control the motor speed has two advantages: 1. It mainly changes the duty of the output square wave to change the average on-time on the load from 0-100% to achieve the purpose of adjusting the brightness/speed of the load. The advantage of using width modulation (PWM) to achieve dimming/speed regulation is the energy of the power supply can be fully utilized and the efficiency of the circuit is high. For example: when the output is a 50% square wave, the power source energy by the width modulation (PWM) circuit is also 50%, is, all energy is converted into load power output. When the common resistor step-down speed regulation is used, to make the load obtain 50% of the maximum output power of the power supply, the power supply must more than 71% of the output power, of which 21% is by the voltage drop and heat consumption of the resistor. 2. The width modulation (PWM) can make the load the full power supply voltage when working, which is beneficial to overcome the internal coil resistance of the motor and make the motor generate greater . The are equipped with external speed control knobs. and reverse control, (, stop, reverse) are equipped with and reverse switches. The chip is used, and the filter capacitor is a monolithic capacitor, the circuit is stable and . The heat sink area used by this speed governor is more than twice of similar on the market, which can the needs of 150W motors. 1. Connect the power cord, the and negative switches are in the middle position, connect the DC power supply, the DC power supply voltage range is 10V, less than 36V, and the output power of the power supply meets the needs of the motor. Do not connect the and negative terminals of the DC power supply in reverse, otherwise The governor may be damaged. 2. Connect the motor, the motor wire can be or negative. 3. Regulating switch, and reverse switch is used to control the direction of motor speed, when the switch is at the position, the motor stops. 4. Potentiometer knob. Adjusting the potentiometer knob can change the output duty of the governor and the motor speed. size:73.5x45.5x27mm Material:ABS+pc colour:Green+black Package Contents: 1 * DC motor speed controller Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.