PWM (Pulse Width Modulation) as Fast As Possible
0 up · 0 down · 0 ratings
Description
PWM is a technology that enables cool things like RGB lighting and variable-speed fans. How does it work? TunnelBear message: TunnelBear is the easy-to-use VPN app for mobile and desktop. Visit tunnelbear.com to try it free and save 10% when you sign up for unlimited TunnelBear data. Follow: twitter.com Join the community: linustechtips.com
PWM, or pulse width modulation, is explained as a method to vary the effective power delivered to an electrical device by rapidly turning the power on and off. The video defines the duty cycle as the proportion of time the signal is on versus off, clarifying that a 50% duty cycle means the signal is on half the time and off the other half, while a 100% duty cycle means it is always on. A key point is that the switching frequency, the rate at which PWM toggles on and off, must be fast enough to avoid perceptible flicker; humans perceive a continuous light around 18 flickers per second, so LEDs are typically driven at around 100 Hz with a 25% duty cycle to appear dimmer without visible flicker. The first part of the video uses LEDs as the primary example to illustrate brightness control and the relationship between duty cycle and perceived brightness at a fixed frequency. The discussion then expands to show how PWM enables quiet, efficient fan speed control for PC cooling, where traditional DC voltage control yielded louder, less precise speeds. It contrasts PWM with older DC-based methods, where power is modulated by changing resistance, noting that wasted power as heat is a drawback of such approaches. The presenter also touches on the broader uses of PWM beyond lighting and fans, including data transmission where pulse lengths encode information, and high-efficiency PWM amplifiers that can achieve much higher efficiency than non-PWM designs, sometimes nearing 99 percent. In addition to the technical content, the video briefly includes a promotional segment about TunnelBear VPN, illustrating the channel’s mix of hardware explanations with sponsor messages. Overall, the video emphasizes PWM as a versatile and efficient mechanism for brightness control, motor speed regulation, and data signaling, while contrasting it with older control methods and highlighting practical considerations like flicker, eye strain, and efficiency.
Topics · technology · electronics · lighting · audio
Questions answered
- What is PWM and what does the duty cycle mean in practical terms?
- PWM modulates power by turning the signal on and off quickly; the duty cycle is the fraction of time the signal is on. For example, a 50% duty cycle means on half the time and off half the time, while 100% means always on.
- Why is switching frequency important in PWM, and what typical frequency is used for LEDs?
- Switching frequency must be high enough to avoid perceptible flicker, which is why PWM uses frequencies well above the flicker fusion rate. LEDs are typically switched around 100 Hz in PWM to appear smoothly lit without noticeable flicker.
- What are common PWM applications mentioned in the video?
- Common applications include dimming LEDs, controlling PC fan speeds for quiet operation, data transmission, and high-efficiency PWM amplifiers in audio systems.