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Seamunky	#1 30/08/2010 - 23h23 Top
Class : Apprenti Posts : 4 Registered on : 30/08/2010 Off line	Hi, I've got 3 x Osram SFH485 - High power 880nm 5mm IR (infrared) LED (emitter) - 880nm 5 mm LEDs infrared: Peak wavelength 880 nm, viewing angle 40 degrees (±20°), radiant intensity min. 25 mW/sr, typ. 30 mW/sr, max. 160 mW/sr, total radiant flux 25 mW, forward current / surge current 100 mA / 3 A, forward voltage 1.3 V / 1.9 V, switching times 600 ns / 500 ns Now what confuses me is "forward voltage 1.3 V / 1.9 V". In the LED Assembly wizard if I put in 1.3V it says I need a 51 Ohms resister... If I put in 1.5V I need a 47 Ohms resister and so on.... Which value should I use? The minimum forward voltage of 1.3? Im just wondering which would be the correct resister for a single 9V battery?
dewey1	#2 31/08/2010 - 00h24 Top
Class : Habitué Posts : 191 Registered on : 25/06/2010 Off line	Did you get the SFH485P or SFH485? A 9 Volt battery will not last very long. Better off using something like this; Did you get the SFH485P or SFH485?
Seamunky	#3 31/08/2010 - 07h30 Top
Class : Apprenti Posts : 4 Registered on : 30/08/2010 Off line	Packaging says SFH485 Its fro RS electronics (their code is 585-242). Apparently the "P" is discontinued. EDIT: OK, got my hands on a 4 cell AA Holder. Will give that a go. Can I use a 27 Ohm resister instead of 2 x 10 Ohm as in the diagram? Edited by Seamunky on 31/08/2010 at 10h31.
dewey1	#4 31/08/2010 - 10h58 Top
Class : Habitué Posts : 191 Registered on : 25/06/2010 Off line	Yes, a 27 ohm resistor will work. That is definitely not a common value. A value between 20 and 30 ohms will work fine. 20 ohm is 75 ma current at 6 volts and 30 ohm is 50 ma at 6 volts. If the led has a flat frontal surface as seen picture in picture, it is the "P" version. See the flat surface near the letter S of top led in pictorial. If it is domed shaped, it is the non "P" version. Read about the the reshaping of the led frontal surface area for better results or take an easier method and reorder from Digi-Key. I purchased 10 SFH485P for $6.81 including shipping ($2.07) from Digi-Key. So I got 9 spares to build clips or hats. There was a price break at 10 pieces. 10 pcs for $.44 each or 1-9 for $.77 each. Almost twice as many for same price. (10 versus 5) Edited by dewey1 on 31/08/2010 at 11h38.
Seamunky	#5 31/08/2010 - 11h26 Top
Class : Apprenti Posts : 4 Registered on : 30/08/2010 Off line	Yeah, 27 is odd...but its what I have lying around. Otherwise, I'll go buy a few 20's. I'll try filing the ir-led's down if I have trouble getting freetrack to work. Thanks for the help
Seamunky	#6 31/08/2010 - 22h18 Top
Class : Apprenti Posts : 4 Registered on : 30/08/2010 Off line	Done, Works like a charm. Just taped it to an old set of headphones...need to make a more... suitable mount. Need to tweak some settings in FT too...but acceptable results in DCSBS, Falcon AF and IL2 right off the bat. Using a Microsoft VX3000 webcam without any IR mods Edited by Seamunky on 31/08/2010 at 22h18.

FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > 9V battery question

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