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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > SFH485P power

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fosamax #1 06/11/2008 - 23h32

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Registered on : 17/10/2008

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I am thinking of using SFH485P ir leds, they are 3v 100mA each.
Which battery?, and resistors?

3 point cap btv.
Edited by fosamax on 06/11/2008 at 23h32.
benmeijer #2 06/11/2008 - 23h54

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Registered on : 19/07/2008

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Take a look here my build: http://forum.free-track.net/index.php?showtopic=466&page=4#8487

1.5 Vf is enough (3Vf is for high freq. pulsing leds), 50 mA current

so if you use 3V from battery use 3 * 30 Ohm resistors
tristan68 #3 11/11/2008 - 08h32

Electronicien en chef
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Hello


1.5 Vf is enough



It's not only enough, it's the operating value.

TRYING TO OPERATE THE SFH485P AT 3V IS AN ERROR. YOU WILL FRY THEM


Also 100ma is a max value.

Please use 75 mA max to power them.
If you use 100mA with freetrack your leds will be overpowered.

About the resistor value, please use the led wizard on the web frontpage, and provide the power supply you plan to use and your leds characteristics (1.5v and 25 to 75 mA, depending of your webcam setup) and it will provide the resistor values.

cya
DButler #4 12/11/2008 - 14h32

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Registered on : 12/11/2008

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Hi all, I have ordered and should receive today 3 SFH485P LEDs and a 30 Ohm resistor. I plan to use a 5VDC cell phone charger as the PS. With the resistor and the LEDs wired in series, sholdn't that work?

Thanks in advance.

DB

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