Circuit Skills: PWM (Pulse Width Modulation)

materials used in this video are available from Genco electronics P W M it might seem like just another one of electronics many three-letter acronyms but the fact is pulse width modulation is a really clever way to use electricity let's say I want to control the speed of a motor because hey it doesn't right well I could use a resistor but holding back all that power can make my resistor really hot and if I'm generating unwanted heat that means I'm wasting power and really nobody wants to do that instead I can supply full power to the motor but just in short pulses a motor takes a little bit of time to respond to abrupt changes so by powering it with a pulse wave that switches between say 0 and 12 volts at a fast rate our motor will behave as if it's getting a steady voltage somewhere between zero and 12 volts we can determine that voltage level by taking the amount of time our pulse way of these on vs. off this is known as a waves duty cycle we then multiply that amount by our pulses high level so our signal has an average of 6 volts make sense on paper but I definitely prefer a more hands-on approach I'll demonstrate using this pulse width modulator kit just have to work together first yeah where was I oh this board uses a specialized chip to convert a DC input voltage into a PWM output signal with a duty cycle proportionate to the DC input voltage level this will make a lot more sense if we can actually see it so to the oscilloscope I'll use my adjustable bench top supply to test the board's variable input and connect my oscilloscope probe to have a look at the output turning up the input voltage causes the outputs duty cycle to increase in other words the pulses width is modulated according to the input voltage level so even though that waveform looks pretty harsh and square it does provide some very smooth and a fish motor control as expected changing or modulating the width of those pulses allows me to control the speed of my motor and that's pulse width modulation but PWM isn't just used for motors the same principle can be used to control lamps brightness or even a heating element not only that pulse width modulation is also used as a sort of simple digital to analog converter in many microcontrollers like say on my Arduino board here this can be really handy when you want to generate a simple audio tone or control the brightness of an LED make it fade in and out so in the end PWM ends up being a versatile and important thing in the world of electronics and if you ask me that's pretty wild man if you're in the mood to modulate check out the DC the PWM kit available at Jame co.com

Channel: Make:

Views: 331,983

Rating: 4.8534317 out of 5

Keywords: PWM, pulse width modulation, motors, electricity, electronics, circuits, diy, Arduino, microcontrollers, Make magazine, Collin Cunningham

Id: Lf7JJAAZxEU

Length: 5min 36sec (336 seconds)

Published: Wed Jun 01 2011