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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > SFH485P resistor question

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Fu®io	#1 20/12/2008 - 14h19 Top
Class : Apprenti Posts : 18 Registered on : 20/12/2008 Off line	Hi to all. I've a question: With 3 leds SFH485P (1,5V - 75mA I think) and 9V battery, what kind of resistor I need? The Led Wizard suggest 80 ohm resistor. Is correct? And what is the correct values (V/mA) for SFH485P? Thank You!
gaedious	#2 20/12/2008 - 16h16 Top
Class : Apprenti Posts : 13 Registered on : 07/12/2008 Off line	FYI, SFH485P max value is 100mA and 3V max. If you would like to mod your camera 20mA would be enough. Otherwise it is recommended to have at least 50-70mA at 1.5V(that's the typical voltage for SPH485P) for an unmodded webcam. I have pretty much the same setup with you, I'm using 9V battery and have 75Ohms, 0.5watts power rating and 1% tolerance of resistor. 75mA is a bit too high IMO. Maybe the guys out there could give a better opinion to prove I'm wrong. Hope that helps.
Fu®io	#3 20/12/2008 - 18h46 Top
Class : Apprenti Posts : 18 Registered on : 20/12/2008 Off line	Thank you gaedious. Then, If I use the SFH485P (1.5V - 75mA), the wizard calculate a resistor of 80 ohm in serial assembly. Perfect.
tristan68	#4 09/01/2009 - 17h23 Top
Class : Electronicien en chef Posts : 651 Registered on : 10/07/2007 Off line	@gaedious : FYI, SFH485P max value is 100mA and 3V max WRONG ! SFH485P max rating at continuous current use (thats the case in all freetrack setups) are : forward current : 100 mA forward voltage : 1.5v (and not 3V) 3V is the forward voltage of this led , when pulse driven at 1A !!! cya
tristan68	#5 09/01/2009 - 17h24 Top
Class : Electronicien en chef Posts : 651 Registered on : 10/07/2007 Off line	@ Fu®io : Resistor value ok good luck for your setup. cya
epokh	#6 13/03/2009 - 15h27 Top
Class : Apprenti Posts : 9 Registered on : 10/03/2009 Off line	tristan68 @ 09/01/2009 - 17h23 a dit: @gaedious : FYI, SFH485P max value is 100mA and 3V max WRONG ! SFH485P max rating at continuous current use (thats the case in all freetrack setups) are : forward current : 100 mA forward voltage : 1.5v (and not 3V) 3V is the forward voltage of this led , when pulse driven at 1A !!! cya Exaclty I just received my leds today and read the datasheet. I'm using 3 Volt battery supply and 4 parallel LEDS: R=15 ohms P=0,15 W as page 9 of the LED manaul. cheers.

FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > SFH485P resistor question

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