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Author Topic: built IR pen! works beautifully! except..  (Read 11546 times)

Offline mindnumbinglyfun

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on: December 28, 2010, 09:55:04 PM
this might sound dumb but i was excited when i first discovered the whole whiteboard thing, so i rushed into this.. i ripped an IR LED out of an old remote.. did not check the viewing angle before constructing my pen..

it looks from what i can see with my digital camera (most can see IR, did you know?) that looking at the LED from the side, and especially the rear-side angle, you can hardly see the light at all. i am doubtful the wiimote will be able to detect this. (havent tried, bluetooth dongle is in the mail!)

i briefly googled my problem and seemed to find an old post on an unrelated subject which happens to also be able wide viewing angles for LEDs. it was said:

Quote
The viewing angle of your LEDs is too small,  increase the viewing angle by filing the LED lens tips down flat, almost to the metal part and then make the final finish transparent matte (not too shiny, not too rough).

Quote
...their viewing angle is too narrow for head tracking but this is easily fixed by filing the lens tips down flat. This reduces their brightness due to a wider emission angle but they're still no less bright than commercially bought wide angle LEDs like SFH485P.

so i am considering filing down the tip of my LED. i am far too impatient to wait for the correct part to come in the mail. i will of course order it, but in the mean time.. will this work? maybe? tips? (how do i make the finish transparent matte??)


Offline boonjin

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Reply #1 on: December 28, 2010, 10:39:24 PM
Quote from: mindnumbinglyfun on December 28, 2010, 09:55:04 PM
this might sound dumb but i was excited when i first discovered the whole whiteboard thing, so i rushed into this.. i ripped an IR LED out of an old remote.. did not check the viewing angle before constructing my pen..

it looks from what i can see with my digital camera (most can see IR, did you know?) that looking at the LED from the side, and especially the rear-side angle, you can hardly see the light at all. i am doubtful the wiimote will be able to detect this. (havent tried, bluetooth dongle is in the mail!)

i briefly googled my problem and seemed to find an old post on an unrelated subject which happens to also be able wide viewing angles for LEDs. it was said:

Quote
The viewing angle of your LEDs is too small,  increase the viewing angle by filing the LED lens tips down flat, almost to the metal part and then make the final finish transparent matte (not too shiny, not too rough).

Quote
...their viewing angle is too narrow for head tracking but this is easily fixed by filing the lens tips down flat. This reduces their brightness due to a wider emission angle but they're still no less bright than commercially bought wide angle LEDs like SFH485P.

so i am considering filing down the tip of my LED. i am far too impatient to wait for the correct part to come in the mail. i will of course order it, but in the mean time.. will this work? maybe? tips? (how do i make the finish transparent matte??)

Hi,

The IR LED from the remote control may not work with the Wiimote as it may have different wavelength from the optimum one needed for the Wiimote.

If you are using it for a wiimote whiteboard, the small viewing angle should be alright as the Wiimote should be capturing the reflection off the screen and not directly from the IR LED. Your issue will be the Wiimote may vaguely detect your emitted LED and thus very bad tracking.

To save yourself trouble, just get the TSAL 6400 IR LEDs or a pre-made IR pen.

Regards,
Boon Jin

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Using a Mac? Now you can annotate on PowerPoint or Keynote slideshows!

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Offline mindnumbinglyfun

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Reply #2 on: December 30, 2010, 11:22:58 AM
ah, i didnt know it saw the reflection of the surface. thank you. i must have read something wrong.

im still waiting for my bluetooth adapter and led in the mail. i did happen to test my pen with the wiimote though, and it works! all i could really do to test it was to set the wiimote on something and have it point at the tv (so i could see the cursor on the wii), then i unplugged the sensor bar (making the cursor go away), then i positioned the pen about where the bar was and turned it on. the wiimote cursor came back! im guessing this means the random LED ripped from an old remote works on the proper wavelength :)


Offline Davo

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Reply #3 on: December 30, 2010, 02:27:35 PM
Congratulations on getting a step closer! However, just because the wimote registers your led doesn't mean it will work very well with it. Any, or all, of wavelength, viewing angle, or intensity, will almost certainly be far from optimal. There are other leds that work perfectly with the system, but unless you know exactly what you are doing, Boon Jin's advice is the way to go. Good luck with your experimenting.

Regards

Dave
3P Interact Ltd
www.3pinteract.co.nz


Offline mindnumbinglyfun

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Reply #4 on: January 27, 2011, 07:31:28 PM
maybe i should have given an update. it works just fine. i guess the odds were very against me but it turns out that random LED from an old remote control works fine.

i do have a radioshack IR LED (940nm). i havent tested it yet (no need to build another pen yet, my one works fine) but when i do i will see if it works any better. my one and only problem so far has been that i am unable to track about half of my 50 inch plasma tv with it. i followed some of boon jins advice on the matter (in his smoothboard faq) and was unable to get good results. looking at the tv through my camera and testing the pen showed me that not very much light at all was reflected. after many attempts to fix this i just decided that my tv absorbs too much light. but maybe a 940nm IR LED from radioshack will work better than this random and outdated LED.


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