Gadgetory

how does your computer put on such a fantastic light show with all those LEDs how the lights fade and change colors is there a legion of pixies with an amazing array of dimmer switches coordinated precisely so that your friends are impressed with your RGB lighting well the reality is a bit less fantastical but with the recent unionization of Pixies we have the much more practical pulse width modulation so what is pulse width modulation PWM varies the perceived power going to an electronic device by very quickly turning the power on and off the perceived output is changed by varying the duty cycle now the duty cycle isn't the time it takes your dog to spin around before going about its business but instead how long the signal is turned on versus turned off this means with the duty cycle of 50% the signal is turned on half the time and off the other half where is a duty cycle of 100% means the signal is always on an important part of the duty cycle is the switching frequency or how fast the signals turn on and off for instance turning an LED on for a second and then off for a second would be a duty cycle of 50% but the LED won't be half as bright it will just be annoying to make the LED appear dimmer the on/off switching has to be faster than the flicker fusion rate or how quickly a light has to turn on and off to be perceived too by the brain as being continuously on in humans the flicker fusion rate is around 18 times per second typically LEDs controlled by PWM will be switched on and off over a hundred times per second or 100 Hertz by using a duty cycle of 25% at 100 Hertz it means that the LED would be turned on and off 100 times per second but the duration of each on cycle is only a quarter of the time making the LED appear 25% as bright and as you probably know PWM is also useful for quiet and efficient PC cooling older fans controlled from the motherboard had very poor speed control meaning that the fans would run much faster and louder than they act needed to be at that point in time pwm fans however allow for the motherboard to easily control the fan speed giving low quiet fan speeds when just browsing the web to gale force winds when you're playing crisis so can we dim alight or change a fan speed without using PWM well older systems might use DC voltage control this works by changing the resistance in a circuit the more resistance the less power transmitted to the fan or light since there is no switching DC control has the advantage of smoother power delivery but they often don't offer the same range of speeds that a PWM fan does not to mention that any power that isn't being used gets wasted as heat which is why old dimmer switches use the same amount of power no matter how much light they made it has been said that PWM monitors can cause eye strain from the constant flickering although makers of DC controlled monitors seem to pretty much be the only ones that are saying this so trust them if you want beyond changing how much power is going to something PWM can be used to transmit data between two devices where pulses of different lengths represent the data being transferred this is how your TV remote switches channels and how data is transmitted from cell towers to your phone PWM is also used in some audio amplifiers making them extremely efficient the typical efficiency of a non PWM amplifier is between 25% and 50% while a PWM amp can reach efficiencies of 99% the cool operation and high efficiency makes these amplifiers popular in car audios you can bump t-swift all day without you know turning your dash into a frying-pan tunnel Bayer VPN allows you to tunnel into twenty different countries giving you the access to browse the internet from that country and they have easy-to-use apps for iOS Android PC and Mac and I also have a Chrome extension just choose a country in the app turn tunnel bear on and watch as your bear tunnels your internet connection to your new location when you do turn tunnel bear on two things 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