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Paladincubano	#1 09/06/2009 - 12h27 Top
Class : Apprenti Posts : 7 Registered on : 20/12/2008 Off line	Hi, sorry my english. I bought 3 Led SFH485P and I want build 3 cap point model with a Cellphone supply 5v in paralel. Question. 3 Resistors??? Value of resistors??? Thxs very much.
babasior	#2 09/06/2009 - 14h45 Top
Class : Webmaster (admin) Posts : 930 Registered on : 09/07/2007 Off line Www	3 resistors ??? YES ! One by each LED ! Value of resistors ??? Look here and enter valu of Spec led (for your leds model Max 1,5V - 100 ma / 70 ma is the best, alimentation 5 Volts) http://www.free-track.net/english/hardware/calcled/ I have made a Pdf document (included with Freetrack 2.2.0.279 Package - Name of document is 3dotscapEN.pdf) to explain how to do an easy 3 dots cap Good luck, Babasior. FreeTrack Online / www.Free-Track.net
Paladincubano	#3 09/06/2009 - 15h41 Top
Class : Apprenti Posts : 7 Registered on : 20/12/2008 Off line	... Look here and enter valu of Spec led (for your leds model Max 1,5V - 100 ma / 70 ma is the best, alimentation 5 Volts) http://www.free-track.net/english/hardware/calcled/ .... 5v I choose unregulated power supply (IE: power adaptar) 1.5V 70 ma This calc show me only ONE resistor 30 Ohms in Serial Circuit. ????? Edited by Paladincubano on 09/06/2009 at 15h47.
CadillacShane	#4 16/09/2009 - 18h14 Top
Class : Apprenti Posts : 15 Registered on : 12/09/2009 Off line	Well if you do ohms law, that's correct, you want to do those LED's in a serial circuit. Furthermore, it is bad practice to run LED's in a parallel. Here read this, and it will help: http://www.kpsec.freeuk.com/components/led.htm#calculate
alonzo	#5 17/09/2009 - 22h19 Top
Class : Apprenti Posts : 3 Registered on : 17/09/2009 Off line	hi! I'm trying to do the same thing,with same led type. my question is : each resistor has the same value ,right ? I mean each resistor will have to be of the same type,identical.same color stripes.? bye
tomsk	#6 01/10/2009 - 13h36 Top
Class : Apprenti Posts : 9 Registered on : 25/09/2009 Off line	What I did was put the 3 IR LEDs in series, with a single resistor. I put the following information into the resistance calculator: http://www.free-track.net/english/hardware/calcled/index.php Battery source: 9V IR LED forward voltage: 1.4V IR LED current: 25mA The forward voltage you should be able to get from the specs for the LED. As for the current, I followed the guidelines here: http://forum.free-track.net/index.php?showtopic=413 Which says My LED's specification says it's forward current is 100mA. So that's what i should input in the LED Assembly wizard? This value is LEDs maximum rating, meaning that it's the maximum current that won't damage the LED. Anything higher may cause permanent damage. Here are some example recommendations for current values for IR LEDs depending on webcam: visible light filter - about 25% of maximum rating. (SFH485P : 25 mA) * stock camera (with IR filter present) and visible light filter applied - about 50%-70% of maximum rating (only use the higher value if the lower isn't too bright). (SFH485P : 50-70 mA) * illumination for reflective tracking (the camera has to be fully IR-modified: ni IR filter and added visible light filter) - 90%-100% of maximum value. When using such high values it's the best to mount LED in a PCB for better heat dissipation. (SFH485P : 90-100 mA) I was using a visible light fighter, with no camera IR filter so I chose 25% of the maximum LED rating. The LED was rated at 100mA maximum so that's 25mA. Plugging all that information into the calculator said use a 200 ohms resistor in series with the 3 LEDs. So that's exactly what I did, and it works great ... well my webcam was a pain in the butt, but the model worked perfectly first time Hope that helps someone Tomsk Edited by tomsk on 01/10/2009 at 13h38.

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