5 leds 4 resistors, how should i do it Options

[rocky2006]

i have a 12v source, (4) 540 ohm resistors, and (5) 3.3v LED's that need ~ 20-25mA each. how do i do this?

EDIT: just did a resistor calculator, and it says the resistors are 560ohm.

This post has been edited by rocky2006: Jun 2, 2005 - 5:01 PM

[SoundSlut_dotcom]

ask clipset tuner

[rocky2006]

pm'ed clipsetuner. is there anyone else that would know?

EDIT: would this work?


This post has been edited by rocky2006: Jun 2, 2005 - 5:37 PM

[DamDirtyApes]

hmmm i think u should have the - of the first led to the + of the secnod then the 2nd led - to the 3rd led + and so on until u get to the last led and connect the negitive wire from the battery to the - on the led

[rocky2006]

i dont think that would work. 12v/5 leds would give 2.4v per LED, and i dont know how many amps they would be getting. i just found this site which shows some diagrams and shows that my proposal 2 posts up should work. ill go try it out and get pics up when im finished, if it works and if i can even do it right.

EDIT: forgot to link the site.
http://www.theledlight.com/ledcircuits.html

This post has been edited by rocky2006: Jun 2, 2005 - 7:01 PM

[mark_426]

It needs to be in series. Parallel will not work, the current would blow them.

http://www.kpsec.freeuk.com/components/led.htm

Try that page, resistance calculators, etc.

[DamDirtyApes]

yeah, what i just said would put it in series

[Snarfer]

you are only going to get 3.2mA per led with that setup, and its generally only a good idea to do a setup like that if all the LED are exactly the same.

This post has been edited by Snarfer: Jun 2, 2005 - 9:42 PM

[rocky2006]

before i waited for replies, i did that setup and i wasnt too satisfied. snarfer was right, i had just over 5mA going through the leds according to the calc. i snapped a pic of that, so hopefully i can get it right tomorrow. here is 5mA, but the pic came out a little darker than it really is:


This post has been edited by rocky2006: Jun 3, 2005 - 2:00 AM

[rocky2006]

if anyone else does this in blue, use a 100 ohm resistor and wire the 3 LEDs in series. this gave me about 25mA and turned out a lot better. other LEDs will require a different resistor. i wasnt able to get pics last night, but ill try to get some tonight. these were the LEDs i used in blue:
http://www.fiberopticproducts.com/danise/c...gory=InvertedWB

[mark_426]

How hard was it to do, did you take the unit out, or do it in the car? Did you use the power from the original lighting?

[rocky2006]

the hard part was finding out how to wire it up. when i found this website it made it much easier.
http://metku.net/index.html?sect=view&n=1&...dcalc/index_eng
i used shoe goo to glue the LEDs in place which took some time to dry. i took the unit out of the car to do some soddering work. i used the power from the cigarette lighter light that way i got 12v and the LEDs would turn on only when the driving lights or headlights are on. some pics of LEDs glued in and glue.