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Mr.RC-Cam

How to use a common LED as a PhotoDetector

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Did you know that a common LED can be used as a Photo Detector? How about this: With some creative microcontroller design work, a front panel LED can also be used as an input device. For example, wave your hand in front of the LED to activate some special feature.

This white paper explains the basics: EDN Design Ideas

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Yes, I remember seeing some great effects produced using an LED matrix, not sure where I saw it though, maybe hack a day. I had a go at using LED's as detectors after that but had no luck.

Terry

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Yep, that was it !

Do you have any good ideas on how to use this idea ?

Terry

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Do you have any good ideas on how to use this idea ?

It seems to me that this technique would be a clever way to emulate a push switch in order reduce size/weight on a micro-sized board. For example, I believe the "How High" R/C altimeter capitalized on this behavior. There's a single LED on it that blinks out the altitude after the user wiggles their finger in front of it.

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