Using IR LEDs for hidden messages

David_AVD

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A random thought popped into my head just now. (Mods, feel free to move this if it's in the wrong section)

It involves using IR (infra-red) LEDs instead of normal (visible) LEDs to make a sign or decoration. It could be words, patterns, whatever.

This means it could only be viewed with a mobile phone or camcorder. It might get everyone taping your display and telling others about it!

Anyway, something to think about.
 

fasteddy

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This is exactly where i told you to put it as its a great idea in its infancy. David did give this a little test with his remote control and his mobile phone and it did capture the I/R LED, give it a try. A very interesting way of adding that surprise element to your display. Think about it, how many people film your display especially with mobile phones to show others. It would have them all wondering whats going on.
 

David_AVD

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Yeah, you could display a message "Hey you with the camera!". :)

I told my son and he came up with the idea of using the IR as a photography watermark. Hmmm...
 

riri7707

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FYI,
it exists 2 kinds of IR range illuminating...

870nm and 940 nm, if i'm not wrong ( i don't have the datasheet under my eyes actually)

870nm, you can see a very little red emission in total dark, when you are in front on the led and 940 nm, this is invisible to the eyes.

Now about the lenght viewing, the 870 nm have long view : can reach 50 meters, when the 940 nm only have limited lenght : around 20 meters.

For performance, 870nm are better that 940 nm... Cameras are more sensitive with 870nm.
You will need a camera with a resolution better than 500 lines to have full details of the scene.


You must to have a cam where you can cut the IR filter in front of the CCD...

I have several IR beams at house, for night security video. Works fine, but you need to consider the angle illumination for good viewing.

FYI, an IR flood with 128 IR led 10mm costs around $50, the lenght 50 meters and the consumption is around 1.5A under 12 volts.

Hope this give you an idea.
Cheers, Henri
 

David_AVD

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I don't know if Halloween projects are (can be) discussed on this forum?

Anyway, another thought is to use IR LEDs to illuminate otherwise hidden (in the dark) props.

Maybe objects could use them directly such as extra sets of creepy eyes in the trees and bushes.

People would be wondering why they can only see these mystical creatures on their camcorder.
 

Mactayl

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I think this a great idea since I have some IR Leds that I've been looking for a use for them and now I can add some hidden effects in my manger display like twinkling stars around baby Jesus that can only be viewed via cell phone or camcorder, Great idea!!!!
 

riri7707

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Hi,
i just relaunch a little this topic regarding IR LED lights.
Even if they can bee seen by a camcorder, mobile phone or security cam, the main problem is the "HALO", they generated. so very difficult to expect to have a clear text to be read, or you need to space each LED more than 30cms....
I have 1000 units on my personal stock, and i used them to build my IR night lights for my security cams.... Only 20 units and you can light 15 meters without any PB. But if you try to look them, big "Halo", at end.
The only solution will be to manage the intensity, using some "circuits", for that.
This is really a "niche" world...

Cheers....
Henri
 
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