led’s in series

Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=68428
Printed Date: May 18, 2025 at 9:47 PM

Topic: led’s in series

Posted By: charlie_one
Subject: led’s in series
Date Posted: December 15, 2005 at 10:19 AM

Hi All

This is probely a silly question, if ill put 3 leds ( 3,3v nom / 3,7v max) in a serie ( - to + on the next led, osv), can ill put 12 volts whit + on the first led and - to the last led ¿¿¿

Or is the only way to use a resistor for each led ¿¿

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Where the asphalt ends, the Pathfinder way begins.

/New nissan 4x4 saying /

Ps sorry for my halfbad english ds

Replies:

Posted By: ff-mike
Date Posted: December 15, 2005 at 2:53 PM

You could use one resistor for the string.

Posted By: charlie_one
Date Posted: December 15, 2005 at 5:09 PM

Is a 470ohm resistor enough for 3 leds, and when ill connect dem ill get all the positive connectors on the led:s to that resistor and the resistor to +12v, an the minus connectors directly to earth ¿¿

Or do ill connect them as in the first post (+ to-), and the resistor on + on the first led ¿¿

Sorry for this simple questions, but im really a novise to this kind of electrical jobs. posted_image

-------------
Where the asphalt ends, the Pathfinder way begins.

/New nissan 4x4 saying /

Ps sorry for my halfbad english ds

Posted By: charlie_one
Date Posted: December 15, 2005 at 5:14 PM

Sorry for the mess above, didnt use my head agine ! posted_image

470ohm resistor enough for 3 leds, and when ill connect dem ill get all the positive connectors on the led:s to that resistor and the resistor to +12v, an the minus connectors directly to earth ¿¿

Or do ill connect them as in the first post (+ to-), and the resistor on + on the first led ¿¿

Sorry for this simple questions, but im really a novise to this kind of electrical jobs. posted_image

-------------
Where the asphalt ends, the Pathfinder way begins.

/New nissan 4x4 saying /

Ps sorry for my halfbad english ds

Posted By: cowboy21
Date Posted: December 16, 2005 at 1:21 AM

it doesn't matter what side the resistors go on, + or - simple =D

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modest yet effective... ECLIPSE 12", Venom 8"x2, Focal 5 1/2" comp.,Response amps x2 (580WRMS total @ 4Ohms), Pioneer TFT + DVD, good for 148.7dB

Posted By: charlie_one
Date Posted: December 19, 2005 at 2:20 AM

Well now ill got it to work, did turn out great, thanks for the help !!!!!!!!!!!

-------------
Where the asphalt ends, the Pathfinder way begins.

/New nissan 4x4 saying /

Ps sorry for my halfbad english ds

Posted By: boyzWidToys
Date Posted: December 22, 2005 at 3:14 PM

i ve actually been experimenting with this. The problem is a car's electrical is NOT a constant 12v.

it varys between 12 and 18 from what i heard.

i attached 3 red led's in series making (assuming 3.3 v each) 9.9 volts.. and connected that across the 12 volts.

it worked fine.

i don't know about life estimate.. or how it would affect. i'm still playing around.

Posted By: charlie_one
Date Posted: December 23, 2005 at 3:25 AM

so its possible to put 4 in a serie and not use any resistor at all ¿

When a car is running its generate just under 14 volts, its only 12 volt when the alternator isnt "engaged", that much ill now.

-------------
Where the asphalt ends, the Pathfinder way begins.

/New nissan 4x4 saying /

Ps sorry for my halfbad english ds