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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Using wires fom Ethernet cable

RSS > Using wires fom Ethernet cable, Are they too thin?

rbonon	#1 09/08/2007 - 16h37 Top
Class : Apprenti Posts : 13 Registered on : 08/08/2007 Off line	Hello all, I am doing a 9V serial setup (4*SFH485P). Is it ok to use the individual wires that come inside normal ethernet cable for connecting the LEDs? Are they too thin for the resultant current (100mA)? Thanks!
Kestrel	#2 09/08/2007 - 17h39 Top
Class : Webmaster (admin) Posts : 780 Registered on : 13/07/2007 Off line	They're more than adequate. 'Clause 33 of IEEE 802.3-2005 (commonly referred to as IEEE 802.3af) provides 48 volts DC over two of the four available pairs on a Cat. 3/Cat. 5 cable with a maximum current of 400 mA for a maximum load power of 15.4 W. ' http://en.wikipedia.org/wiki/Power_over_Ethernet A 9V battery will have a short life at 100mA, I hope you're using rechargeables. Support FreeTrack
rbonon	#3 09/08/2007 - 21h12 Top
Class : Apprenti Posts : 13 Registered on : 08/08/2007 Off line	Kestrel, thanks for the information. Actually, I am waiting for my 4 SFH485P to arrive, and I have 30Ohms 0.5W resistors. In another post somebody (I think it was you) mentioned I should use a higher resistance. What would be your suggestion considering 9V, 4 SFH485P in series? Thanks for your help.
Kestrel	#4 11/08/2007 - 08h04 Top
Class : Webmaster (admin) Posts : 780 Registered on : 13/07/2007 Off line	The choice of resistance is specific to your lighting conditions, as long as you don't have a problem with background light you can increase the resistance. Try doubling it to 60 Ohms, if you can't block enough background light so that only the leds are visible, you've found your upper limit and should choose a value between 30 Ohms and 60 Ohms that will be optimum for you. If you don't mind temporarily losing the visible light capabilities of your webcam, open it up and take out its IR filter (google it for guides), this allows you to use a much higher resistance, with the leds still remaining visible to the webcam, making your battery last much longer. Instead of 30 Ohms you might be able to get away with as much as 150 Ohms (5 times longer battery life). Support FreeTrack

FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Using wires fom Ethernet cable

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