Knob control PWM to adjust motor speed/light brightness scheme
PWM Adjustment Instructions
The solution about PWM调速and light brightness adjustment has a wide range of applications in the circuit of motor speed adjustment or light brightness adjustment. Of course, it is not limited to these two applications. Other applications such as temperature control, adjustment of the water output of DC water pumps, etc. Learn how PWM regulates your device
1. It PWMis composed of many signals whose high and low voltages are constantly changing. If our LED light is on 高电平(高电压)when it is on 低电平(低电压), it will be off when it is on.
2. The process of PWM controlling the LED light on and off is a process of switching between high level and low level 高电平的时候亮低电平的时候灭. We only need to control the high level time and the low level time to be the same, then the LED light will keep on and off. On off flashing
3. The human eye is 50HZnot sensitive to the flicker of a frequency above (50 times per second), and the 80HZabove flicker is basically insensitive. We only need to PWM的频率increase the number of LED flickers to control the human eye. until the LED blinks
4. We can't see the LED lights flickering here. If the brightness is adjusted, we introduce 占空比the concept to adjust. It is simple to understand that a complete bright time plus off time is a complete cycle, refer to the above picture
5. We only need to control 高电平的时间大于低电平的时间the light for a longer time, then the phenomenon we observe when the LED is flashing is 亮度上升the same, and we can also observe the same conversely.亮度的下降
Knob to adjust PWM
Considering that the user-friendly way to adjust the light brightness or motor speed is to use the knob to adjust, Amway is a small voltage-to-PWM board with a potentiometer knob interface.
The power supply range can work under 3~30Va wide range of voltages, covering the working voltage of most DC devices. The on-board interface can directly change the brightness or speed by WH148电位器welding a potentiometer to power consumption . 调节PWM的占空比By default, an LED light is turned on. You can also see the change of its brightness while turning the knob.
complete circuit
Referring to the pin diagram on the back above, our hand-drawn knobs adjust the light brightness and motor speed for wiring reference
Use matters
Above, we also matched a L298Nmotor driver board to drive the motor. The blue knob turns the PWM board's PWM output 信号and does not have a high-power output to drive the motor.
Therefore, we need 电机的电压与电流to choose a suitable driver board driver according to our parameters.
It is worth noting that the PWM signal output port 无法直接接电机, even if the manual has a 100Ω current limiting resistor onboard for protection, does not mean that the wrong connection will not cause damage to the board.
Summarize
The main function of the board is 模拟量调节PWM占空比the function, and the external knob is very convenient for users to quickly realize the function 旋钮调节when they need to use the function.无需搭建外部电路旋钮调节电机转速或灯光亮度
The price of the small board itself is also a good choice for this type of product. In the manual, the waveform drawn by the board oscilloscope of the op amp solution used in the market is stable, and the current test is a very standard square shape in the complete 0 - 100% 的占空比range . Wave, the square corner of the waveform turns into an arc slightly after loading, and it is basically impossible to see that it is completely within the acceptable range without magnification.
This issue of this article ends here with a board like this from Amway. I hope Uxin can accompany everyone to learn and make progress together. Welcome to one-click three-link, thank you all!