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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Confused noob... 3-led setup not working

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Citizen86	#1 18/03/2009 - 07h07 Top
Class : Apprenti Posts : 9 Registered on : 17/03/2009 Off line	Alright, so my 3-point model isn't working like it's supposed to, as in, turning on. I have a 9v battery, with 3 IR LED's. They are 1.3v, 20ma LED's. LED Assembly guide said serial assembly, 270ohm resistor. So I put battery positive to 1st led positive, 1st led negative to 2nd led positive, etc, 3rd led negative to resistor, resistor back to battery negative. This is my first time soldering LED's and such, so I'm not even exactly sure how to test, but in testing DC Voltage, the 1st LED is only showing as .58 with my multimeter under 20 range... 2nd LED shows .56, but the 3rd LED shows as 7.75 Did I set this up wrong? Is something blown? Thanks for the help in advance.
bibic0711	#2 18/03/2009 - 07h25 Top
Class : Apprenti Posts : 12 Registered on : 12/11/2008 Off line	Resistor should go before the first LED positive side (battery -> resistor -> LEDs -> battery)...
Citizen86	#3 18/03/2009 - 14h50 Top
Class : Apprenti Posts : 9 Registered on : 17/03/2009 Off line	Yeah, I did that originally because that seemed to be correct, but same thing was happening, no power on the first two lights, lots on the last one.
FJM	#4 19/03/2009 - 00h51 Top
Class : Apprenti Posts : 2 Registered on : 14/03/2009 Off line	Seems like the LEDs are wired with polarity reversed. Also, you should aim for less than 20mA current rating of the device; i.e. increase limit resister (say 470 ohms) to check things out. Reduce later if needed.
Citizen86	#5 19/03/2009 - 04h30 Top
Class : Apprenti Posts : 9 Registered on : 17/03/2009 Off line	Thanks FJM. I read that usually LED's are longer connection = positive, negative is shorter. Is it possible that it's sometimes reversed though?
Falstar	#6 19/03/2009 - 16h00 Top
Class : Apprenti Posts : 44 Registered on : 25/09/2007 Off line	Citizen86 @ 19/03/2009 - 04h30 a dit: Thanks FJM. I read that usually LED's are longer connection = positive, negative is shorter. Is it possible that it's sometimes reversed though? It's possible. Some companys don't follow the standard.
Citizen86	#7 07/04/2009 - 03h36 Top
Class : Apprenti Posts : 9 Registered on : 17/03/2009 Off line	Okay, new bump... I bought new LED's, a new resistor, and tried this again. This time there is voltage going through the LED's... but still not being picked up by my webcam. It for sure picks up IR lights because I used it with a remote. So I did battery positive to resistor to positive led 1, etc... The first and second LED are showing up on my Multimeter using the 20 DC setting (I Don't know if that's how you say it correctly) as ~9.3-9.4V... the 3rd LED shows up as negative 9.3V. I thought maybe I made a mistake and connected negative to positive, so I switched that LED, and it still shows as negative.... I have no idea what's up with this. Any ideas?
Citizen86	#8 07/04/2009 - 06h24 Top
Class : Apprenti Posts : 9 Registered on : 17/03/2009 Off line	Yikes my bad, I was measuring incorrectly... Anyways, everything IS lined up correctly: + Battery to resistor, resistor to + LED1, - LED1 to + LED2, - LED2 to +LED3, - LED3 to - battery. How it is though, is positive on LED1, NEGATIVE charge on LED2, and positive charge on LED3.... I don't know what the crap is going on. But I do know that it's not working and my webcam is not picking up any lights, although I know it is capable of it.
Fanboy1337	#9 07/04/2009 - 12h10 Top
Class : Apprenti Posts : 22 Registered on : 03/04/2009 Off line	did you try different orieantations of all LEDs? as FJM suggested? the SFH485p's cathode (-) for instance is the longer leg Kind regards from Germany. Setting up my Freetrack for www.jumpgateevolution.com
Citizen86	#10 07/04/2009 - 16h51 Top
Class : Apprenti Posts : 9 Registered on : 17/03/2009 Off line	I checked the spec sheet on these LED's and it's the standard longer is positive... I also checked because the short end of the metal INSIDE the LED is positive, and that lines up with where I've placed everything. I'm just a little confused, it is supposed to show up like that on a multimeter? 9 volts through LED 1, -9 through LED2, and +9 through LED3? I ask because the lights are not turning on.... I could try flipping LED2 I suppose, but I mean... I've checked every connection about 5 times, everything looks the way it should.
Citizen86	#11 07/04/2009 - 21h02 Top
Class : Apprenti Posts : 9 Registered on : 17/03/2009 Off line	Alright, I figured it out... I was using protoboard and it had copper on it... I didn't realize that the copper would transfer across the board because I was just soldering parts together. SO although the negative battery lead was no where near LED2, the negative of the LED2 was technically in contact with negative battery. Looks like I'll perhaps buy a hat and do a 3-point hat after all... that should be less confusing, heh...

FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Confused noob... 3-led setup not working

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