LED tails, Not for the ho'

[steve-o]

Well, this has to do with my ATV, not the alero. I'm thinking about creating a LED tail light for my bike. What I cant figure out is how would I make the LEDs dim for tails, and the brite when brake is applied.

I know that max volts for LEDs is like 2.2, So I was thinking I could wire up some resistors for half that for just tails, and then they would get the full 2.2v when the brake is applied. But how would I wire that up, would I need one set of resistors for lets say 1.1v and then another for 2.2v, or will two sets of 1.1v resistors give me 2.2v?

I know there are a lot of guys on here that have worked with leds before, for me this is the first, so thats why I'm asking.

And the reason for the LED tail lights is not for looks, but to save on power draw, there is a lot of power accessories, so I'm trying to save as much power as possible where I can.

[cherrington17]

so you want dim for your tail lights... but bright when the brake is applied? on the same set of leds??

[steve-o]

you got it.

[cherrington17]

This was easier then trying to explain it...

[teflone]

Looks sounds.. except for the high voltage..

but your math is right..


There is a more complex way of doing it with less parts using tansistors..

But for the first timer, that diagram is good..

[cherrington17]

keep things simple. its easier to work with.

makes me wish i took more electrical classes before i lost the change to take bs classes that don't matter. i could have actually learned the proper way to do things...

[steve-o]

I'm a little confused becuase in the diagram you show the LEDs are in series, according to this webpage http://www.theledlight.com/ledcircuits.html if I hook them up that way using a 12v source, then I could only hook up 4.

wait, now that I think about it, I could hook up a few rows of 4 LEDs in a series, correct?

[cherrington17]

if your using reds... you'd need 5 in series. 2.6Vx5=13V

for series, your adding the voltages of the leds. for parallel, your using each individually (hence why you need resistors) you can do either...

for my diagram, you need to connect each power wire to the power line on the leds. i just think several in series will be easier for your setup.

[The-Ghost]

the bulb in the bike right now is probaly a dual filliment bulb. so one lights up when the bkie is on and the other when you break. that give you the dimming and brightening effect. inorder to acheive the same effect with leds would would need 2 seperate curcuits one for the standard driving lights. and a second that activates when the break is used.

so if your runnig 50 leds (tightly packed) you would problem want to wire only 20 of those to the runnig lights leads. and the other 30 to the break light leads. your best bet would be to run in parallel useing restsers to drop form 12V to 2.5-3V for the leds. i hope you can make out what im trying to describe

[steve-o]

yes, your right, and I was actually thinking about going that route, seems like it would be a hell of a lot more easy. I guess I'm just gonna have to get a shit load of LEDs and experiment.

[teflone]

The voltage dropping way is the smarter and better looking way..