- What it is - A pulse width modulation PWM based motor control circuit designed to adjust the load brightness or speed by changing the duty cycle of the output from 0 to 100 percent. It is commonly used for lamp dimming in a DC loop and for speed control of DC motors, providing a compact motor control solution built on the PWM principle. - Key benefits - High efficiency and full use of the power supply - The load receives power in short on/off cycles, allowing the supply to be used efficiently while the on-time delivers the load voltage. - Precise, wide range control - By varying the duty cycle, you can smoothly adjust the load from 0% to 100% without changing the supply voltage. - Improved motor torque - Because the load can maintain full supply voltage during the on phase, the motor can overcome coil resistance more effectively and generate higher torque. - Simple, scalable control - PWM provides straightforward dimming or speed control without relying on wasteful linear regulation. - How it works - The output waveform is a rectangular (square) wave whose duty cycle is modulated to control the average load power. - As the duty cycle increases, the average power to the load increases, enabling brightness control for lamps or speed control for motors. - In a simple resistive speed control, the load might receive only a portion of maximum output unless the supply delivers more than a certain threshold; PWM avoids this by switching the full supply voltage to the load during on-time. - About heat and losses - In some configurations, part of the input power is dissipated as voltage drop and heat in the resistor path, estimated at around 21%. PWM focuses on keeping the load voltage high during on-time to maximize performance. - Important attributes - Function: Dims DC loads and controls DC motor speed via duty cycle modulation. - Compatibility: Suitable for DC lamps and DC motors requiring dimming or speed control. - Performance: High efficiency through full-voltage on-time to the load; enables smooth, reliable control across the full 0-100% range. - Internal considerations: Some power loss may occur in circuit resistors depending on the configuration. - Use scenarios - LED lighting project in a DC circuit: achieve smooth brightness levels from off to full brightness by adjusting the PWM duty cycle. - Small DC motor control in a robotics project: ramp motor speed with precise, repeatable control while maintaining good torque. - DC-powered equipment in an industrial setup: regulate speed or brightness of DC loads without wasting power through linear regulation. - Practical notes - The control is designed to maximize power supply utilization and improve overall circuit efficiency. - The approach is particularly advantageous for applications where maintaining voltage to the load during the on phase improves performance, such as overcoming motor coil resistance to achieve higher torque.