Circuit Skills: Pulse Width Modulation

By Collin Cunningham

Pulse Width Modulation (PWM) is a very clever way to use electricity to control analog devices via a digital signal. It's a very simple method and is very efficient in driving motors, lamps, LEDs and more! A perfect example of using PWM is if you've ever faded an LED with an Arduino:

Make Logo

Fading
Demonstrates the use of the analogWrite() function in fading an LED off and on. AnalogWrite uses pulse width modulation (PWM), turning a digital pin on and off very quickly, to create a fading effect.

However, you don't need a microcontroller to generate a PWM signal. The 555 timer chip can be configured to modulate its output duty cycle in response to a potentiometer – with the help of some simple circuitry.

Pulse Width Modulator Kit




For a more robust solution, you may want to consider the DC to Pulse Width Modulator kit suitable for sending up to 6.5A of current and built around the Motorola SG3525 – a chip dedicated to the art of PWM.

Of course, Collin would be denying his own nature if he didn't mention at least one audio-related application. PWM comes in handy for generating simple sounds and melodies from a microcontroller.

Arduino Simple Sounds
Wavetable Melody Generator

Click here for the Velleman K8004 data sheet.

Other Circuit Skills DIY Videos by Collin:

Circuit Board Etching
Function Generator and Enclosures
Fiber Optics
Infrared Light Barrier
LED Color Organ
LED Matrix Kit
Perfboard Protyping
Power Supply
Surface Mount Devices


If you decide to build the DC to pulse width modular kit, we'd like to hear about your results! Send your story to MyStory@Jameco.com