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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Help with IR LEDs...

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aceshigh #1 10/02/2009 - 23h01

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Apparently, the electronic stores at my city are not specialized at ALL in LEDs.

I didnt find any OSRAM SFH485P... and no store I went to had any deep info on the LEDs... they just knew they had emitters and receptors, 3mm and 5mm and infrared or other colors.

In one store they at least had the model of the LED... they said it was a PHIV 590, but I cant find ANY INFO AT ALL about this LED model on Google!

Thus, I cant even fill out the LED Assembly Wizard, because I have 3 leds with me which I dont know their voltage nor current!
aceshigh #2 11/02/2009 - 19h22

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btw, what does "filing their lens tips down flat" means after all??

I have no idea what that is supposed to mean... :(
mehmetbeyoglu #3 12/02/2009 - 10h08

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I am using plain white leds and it is working fine with my webcam.

I experienced that if you dont want to light up the room with that weird thing above your head then you must buy those rare infrared leds. Otherwise you can use any leds. (Neigbours --from hell-- could easly mis-judge you after 35+,  trying to find out why you insist on  illimunating your LCD )

The most important thing about the leds is that they must be wide angled so that when you yaw/pitch your head the camera can still see the light.

No need to mention you must ask the voltage (to calculate the power need) and current (to calculate the resistance) of the leds to the seller so that you can pick up the right power and resistance. Beware... there is a possibility that you burn the motherboard if you pick usb (5Volts) as a power source and miss configure the current/resistance.

If the seller doest answer your questions as desired then there is no point of buying them. An experienced technician can measure the values with a device.
Edited by mehmetbeyoglu on 12/02/2009 at 10h20.
las6 #4 14/02/2009 - 14h04

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Yeah, normal LEDs do work fine in most conditions, if they're bright and wide enough. I'm using a 3,5 € IKEA christmas led light series that works on two AA batteries. I simply blacked out (tape/cardboard atm  :p ) the leds I don't need and I haven't had an issue with the room lighting or anything like that. The software is the problem... along with the focal length of the webcam (not wide enough, so you need to push it further).

Of course IR leds should be better, for all the reasons mentioned above, but I don't see that they would be required in order for the tracking to work. (Especially the reason that you're bound to look a little silly with christmas lights on your head. )

But go ahead, experiment.
vagos #5 15/02/2009 - 23h00

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You dont really need the IR Led specifications. You can always assume 1.4V forward voltage and around 100mA forward current.

Using 1.5V I'll reccomend 3 resistors with 1Ohm value.
3V use 10Ohm's roughly. You can experiment with your design freely.



btw, what does "filing their lens tips down flat" means after all??



Well if you look the led there is a small metal inside. Trim the plastic all the way down to the metal level. (Not too close though you will destroy the LED). By doing that the angle of radiation will be enough for free movement.

Good luck
Edited by vagos on 15/02/2009 at 23h00.
aceshigh #6 16/02/2009 - 18h05

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cutting open the led? Isnt it vaccum inside? If I cut the led plastic (trim it) wont it expose the inside the air and severely decrease the life of the LED?
Falstar #7 16/02/2009 - 18h34

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aceshigh @ 16/02/2009 - 18h05 a dit:

cutting open the led? Isnt it vaccum inside? If I cut the led plastic (trim it) wont it expose the inside the air and severely decrease the life of the LED?



The plastic is molded around the metal.  You are just flattening the top off.

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