> IR LED, 1.2V, 20mA, 940nm, Will this one suffice?
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JayPee |
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Currently I can only get my hands on a 5mm IR LED with the following info provided by the store:
1.2V
20mA
940nm
manufacturer's code IRS5
However, will this LED suffice? Is the 20mA enough as I've read a lot about people using 70mA and 100mA LEDs, and LEDs with a higher voltage?
Secondly, I find the following a bit odd. 'They' say that I should file off the LED to get a flat top on it. This should be done to generate a forward aimed light beam instead of an omnidirectional light bundle. But, I've also read that a LED should be powerful enough so as to be seen by the cam from the side when I turn my head and the LED is placed under a high angle.
So what's up with this? Do I have to keep it orb shaped to direct the light both forward and sideways, or do I have to file it off?
Nevermind this last part. I mixed up the effect of a filed off LED vs a non-filed one.
Edited by JayPee on 12/01/2013 at 12h41. |
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JayPee |
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Is this community still active anyway?!
Edited by JayPee on 14/01/2013 at 10h34. |
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Steph |
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Hi,
... will this LED suffice?
Only a try will give you the answer.
It depends as well on your webcam and filter you use.
The IRS5 given with 3.31 mW/sr is on the low end of radiant intensity of the SFH485P, given between 3.15 an 5.5 mW/sr.
A good daylight filter will be required. |
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JayPee |
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And the amount of mW/sr is directly dependent on the amount of mA I allow to go through the LEDs?
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Steph |
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Yes, as long as if you don't overstep the max permissible forward current.
Good page for informations about LEDs. |
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JayPee |
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Thanks for your help so far.
It seems I can get my hands on one other IR LED which appears better than the one in my opening post. It is the Siemens/Osram LD274 of which the datasheet can be found here: http://www.datasheetcatalog.org/datasheet/siemens/LD274.pdf
The stats. look much more promising although the LED is made to be a small angle +/-10 deg. off centre LED. Can I completely overcome this issue by filing it or can I only acquire a limited improvement which won't be enough for a LED which has such a small native angle?
Your judgment is once more appreciated! |
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Steph |
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Hi,
I used the LD274 in a earlier mount:
It works quit well, except for, (as you always mentioned), the small beam angle of +-10°. Allows you +-15° real-head-turn, which is to small to get good precision with a 180° in-game-turn.
But you can file them down without any problems.
Use a file or nail-file or 120 sandpaper and finish with fine 800-1000 sandpaper to produce a convex surface. You don't need a real transparency finish. A light opacity is ok. |
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JayPee |
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Do you mean 15 deg. real-head-turn with an untouched LD274, or 15 deg. even when it's properly filed down?
Btw, your design looks pretty neat! What is the output DC of that power adapter? I have a spare power adapter which has a DC output of 5.0V. Came with a USB hub...
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Steph |
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Yes, I mean you can reach about ~-+15° real-head-turn with a non modified LD274, which is not much and often leads to lost tracking dots on the edges.
With filed down LEDs it can be as good as the SFH485p I think.
This is an old mobile charger with 5V output.
You can use your USB power adapter, it's perfect.
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JayPee |
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Great! Thanks for all the help.
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toprak |
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Hi, can you let me know what ~angle you achieved after filing for LD274 and what current rating you finally settled with?
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JayPee |
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This topic was just a bit of preliminary research for me. I won't be making it anytime soon. It'll going to be atleast another 5 or 6 weeks. It was just to check whether it is viable or not. But I will report back when I'm done.
Edited by JayPee on 19/01/2013 at 12h07. |
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Steph |
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toprak @ 19/01/2013 - 05h18 a dit: Hi, can you let me know what ~angle you achieved after filing for LD274 and what current rating you finally settled with?
You will easily reached the SFH485p beam-angle of +-20°. Driving them
with 70-80mA is the right compromise between good radiation intensity
and good lifetime.
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