Recently, I built a small PWM (Pulse Width Modulation) dimmer for an LED light I have. It's based on a DC motor controller that uses a 555 timer chip.
The tutorial that I used to build the dimmer can be found at:http://www.dprg.org/tutorials/2005-11a/index.html
Pulse Width Modulation is pretty neat. You can use it to vary the brightness of LEDs, change the speed of a DC motor, or even run a Disco Ball at whatever level of partying-hard is required.
Please watch the video for an explanation of using PWM for a few practical uses.
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