I am looking for information about wiring resistors into a series of multiple LED bulbs. I searched and everything and could not find a definite answer on google. I am doing some DIY LED projects on my Z and I know I can do the work, but I want to make sure I am doing it right. Basically I am wanting to do multiple LED bulbs (~15) in a straight line in a series circuit with white and amber bulbs in separate strips. I did the resistor calculator and everything and it told me to do 3 resistors for 5 bulbs. Basically my question is, where should I place the resistors? I know I should start the initial resistor on the positive charge. Should I do the series in sets of 3 bulbs instead? Thanks

Diagram of what I am thinking: ---wire [either +/-] (+Anode *LED -Cathode) R Resistor

Positive----R (+*-)(+*-)(+*-)(+*-)(+*-) R (+*-)(+*-)(+*-)(+*-)(+*-) R (+*-)(+*-)(+*-)(+*-)(+*-)----Negative

or should I do

Positive----R (+*-)(+*-)(+*-) R (+*-)(+*-)(+*-) R (+*-)(+*-)(+*-) R (+*-)(+*-)(+*-) R (+*-)(+*-)(+*-)----Negative


or is this all completely wrong?? lol

Edit: http://led.linear1.org/led.wiz Calculator I used

I found that amber LED bulbs required sets of 3 bulbs with resistors in between and white bulbs were schemed as sets of 5 bulbs with resistors in between

 

this is how i would do it.....

http://i42.photobucket.com/albums/e3...olf177/led.jpg

 

here is a beter pic lol

http://i42.photobucket.com/albums/e3...f177/lrddd.jpg

 

i have that last schematic from the calculator wizard i used, but I am a little confused by the first drawing you posted. why do you have to take each set of LEDs back to the negative wire? is it not possible to just make one long chain with the bulbs and resistors? So based on your drawing, do you need to expose the entire wire (remove rubber coating) to solder each led (at the end of the set) or resistor onto the wire?

 

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any other advice anyone?

 

The reason why he has multiple "sets" is because of the way leds/resistors work.

Each led will drop about 2.5v and need a max of 20ma of current ( depends on size and color of led). That means a 12v battery can really only supply voltage for 4 leds in a row, really 5 since your car battery is >12v. So, in order to supply 15 leds you need at least 3 rows of 5 minimum. You could do 5 rows of 3 as well.

Depending on the characteristics of the leds, youll will need to size the proper current limiting resistor. Normally a 300 ohm resistor will suffice since it would flow 40ma with the full 12v across it (which wont happen). Leds require very little current to turn on.

So, all you need are 15 leds and 1 resistor per setup. You can use 3 resistors but its not necessary as long as your led's parameters dont vary greatly.

 

Thanks! I think I have it now! I appreciate the help!

 

dont forget when the cars running its 13.9 ~ 14.1 volts.. and when its off a lil under or around 12v