1157 LED bulb

[NightShift]

I was wondering if it was possible to modify this 1157 LED bulb from 12 volts down to 6 volts by changing a resistor or something.
I dont know whats up with the diodes and stuff and what they do...can someone fill me in to understand what the diodes and other components are doing and if its easy to step this down to 6 volts. If not..do you know where i can get 6 volt 1157 LED arrays (similar to the ones at theledlight.com, but less expensive)?

Im looking into getting them for my old moped because the regular incandescents seem to put a heavy load on the electrical system (taillight goes slightly "dim and bright" as directionals flash, headlight & speedometer light go slightly dim when brake is applied) The battery was replaced....its only a small 4AH battery.

Anyway heres a picture of the circuitry of the 12 volt 1157 LED:



Sorry they are so big [img]images/icons/rolleyes.gif[/img]

[NightShift]

Does anyone have any idea?

[lightuser]

Nightshift, we're no expert, at your own risk, but what I would do is hook the bulb up to 12 volts and probe on the solder welds with a multimeter for voltage values. This will give you an idea what it's using, and where. Most leds like no more then 2-3 volts, so they've stepped it down with the resistor, and they're mostly in series, not parallel. You can determine the polarity and input values of each led with a mutimeter, and by looking thru the epoxy, the cuplike part is the +. I don't know why they have a diode in there (anyone-?). Maybe it's just protection against polarity reversal. What you may want to do when you figure out what you've got is rewire it according to what you learn about the existing circuit. Your voltage of 6V, the required amp draw of the leds (25mA or so/ea.) and resistance will need to be calculated all over. See www.misty.com/~don/ledd.html that's where I go for the formulas...good luck and be patient...and remember if you don't tear it up it doesn't have enough features yet.
[img]images/icons/smile.gif[/img]

[Dizney]

Nightshift.......just wondering where you bought those 1157 LEDs from and have you used them on your car?

Thanks!

[NightShift]

Hi dizney. I surprisingly found them in pepboys near me when I was just looking around....and of course I had to buy some.

I put them in my car, but they only light up a concentrated small spot on the lens. I'd much rather have the whole taillight lens light up as much as I like LEDs. The bulbs are really meant/good for aftermarket taillights...probably the ones that have the red circle lenses (that might magnify the bulb) and the rest of the taillight that is clear.

My taillights draw so much (halogens) that I was going to consider just throwing the LEDs in instead.

[Dizney]

Thanks for the info! I used to have some halogen taillights from DesignTech (also got em from Pepboys)but they only lasted a couple of years.

[Bart]

unfortunately those 1157 replacements aren't very bright. I'm sure just one luxeon on there would be brighter than all those LED's combined. They may seem bright straight on, but their viewing angle is only about 15 to 22 degrees. I use to use them in my truck, when I had my truck, and on a sunny day there was no way to tell I had my brakes on.