Monday, March 30, 2009

Electronics: Pulsing/Breathing LED

A few months ago I was looking to create a “pulsing LED” effect. What I was using this for was for a Halloween effect where I was placing a series of different colored ultra-bright LED’s under some beakers filled with water and dry ice, creating the Mad Scientists lab. One of my stated goals was to do this without using a microcontroller since I hadn’t gotten into microcontrollers yets.

I ended up using this project:

This essentially makes a scewed triangle wave, where the rise time is quicker than the fall time, creating a “breathing” effect.

There are a couple of other circuits that do similar things:

Of course, making a variable duty cycle PWM program with a microcontroller might end up better next time since I can control more LED’s with less.

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