LEDs..how to go from 12v to 6v, I got 2 6volt leds and I need to tap them onto 12v power Options

[Black0nBlack94]

Any body have any idea how or what I should use to make a 6volt LED light on a 12volt power supply? I know that if I tap it on directly to the 12volt it will burn but I cant figure out how to make it light without burning. I want to install 2 blue LEDs, one on each door behind the lock and I plan to take power from the courtesy light. But After the current leaves the courtesy light and before it reaches the LED...I need to lower the current. I think I need a resisitor but I dont know specificly which one. If anyone has done this before let me know what I need to do. Thanks 6gcers

[mkernz22]

honestly, it would be easier if you got 2 LED's that are 12v

[freddy121389]

find what bulb size you need and buy them from this site, they're amazing and replace factory bulbs http://autolumination.com/

[Zimluura]

cool project.

you'll need the led current too. but this will tell you.
http://led.linear1.org/1led.wiz

to get a big enough resistors you might need to go with these guys
http://www.mouser.com/
you'll need the led current too.

that being said, you can always get led + resistor fabrications at autolumination.com and just solder their legs to your wires. might even be able to find sockets for them so you can have a replaceable bulb.

This post has been edited by Zimluura: Sep 19, 2010 - 11:10 AM

[freddy121389]

cool project.

you'll need the led current too. but this will tell you.
http://led.linear1.org/1led.wiz

to get a big enough resistors you might need to go with these guys
http://www.mouser.com/
you'll need the led current too.

that being said, you can always get led + resistor fabrications at autolumination.com and just solder their legs to your wires. might even be able to find sockets for them so you can have a replaceable bulb.

they come fabricated automatically with resistors and sockets. i love them just pop it in and your good

[malpaso]

Any body have any idea how or what I should use to make a 6volt LED light on a 12volt power supply? I know that if I tap it on directly to the 12volt it will burn but I cant figure out how to make it light without burning. I want to install 2 blue LEDs, one on each door behind the lock and I plan to take power from the courtesy light. But After the current leaves the courtesy light and before it reaches the LED...I need to lower the current. I think I need a resisitor but I dont know specificly which one. If anyone has done this before let me know what I need to do. Thanks 6gcers

what you need is "burn" 6V somewhere... there are two options how to do that:

a) use two 6V LEDs (they share with 12V together and not burn)
b) use resistor that will "burn" 6V. Resistor value you calculate from this: R = 6 / I (I is current in Amperes with that LED works with)

[Zimluura]

here's another one that will help you with series of leds if you decide to go that route
http://led.linear1.org/led.wiz

when i tried to put in 6V leds it said that the number was "suspiciously high". are you sure they're not 3.6V?

[Black0nBlack94]

Hmmm, Im not exactly sure...you see I got them out of a toy wand my tenants daughter broke...I decieded to mess with it one day and I found out its bright as s%*T. So I decieded to put them behind the door lock. I can light them on a varad LED circiut board that makes an LED flash like an alarm when you take the key out the ignition, visual theft deterence {keep dumbasses from breaking into your car if you cant afford an alarm system}...I've beed searching to find out the voltage output on the cicuit board but so far no luck. there is a good possibility that its 3.6volts though. I figured if I cant do that then I would buy bright 12volt LEDs from somewhere...But in that case how many mcd is bright enough? Could someone compare it to something I can see?...the guys in radio shack refuse to show me them before I buy. They have all different ones. 200mcd 250mcd 1000mcd 2000mcd 5000mcd.Thanks lemme know if anyone find out anything I dont know yet

[jlive]

How to get 6V from 12V (V=IR, Voltage = Current * Resistance)

12V --- R1 --- R1 --- Ground

Let R1 equal a resistive value. Say 1 Ohm. The wire between R1 and R1 is then at 6V (12V/2 Ohms = 6 Amps... 6 Amps*1 Ohm = 6V). The Amperage going through the circuit though is high, 6 amps.

So lets make R1 a bigger resistive value. Say 1000 Ohm. 12V/2000 Ohm = .006 Amps... .006 Amps*1000 Ohms = 6V. The amperage then going through the circuit is 6 milliAmps.

Either way you get 6V between R1 and R1.

So adjust the resistors until you get the current value you need. Just make sure you keep the two resistors the same value, and that they can handle the amount of current being pushed through. Also make sure you also use a wire that can take whatever current your pushing.

Place the LEDs in between the two R1 Values like so:

12V --- R1 ------------- R1 --- Gound
.................|.........|
...............LED.....LED
.................|.........|
...........Ground..Ground

Ignore the periods, everything got shifted left when I posted it.

Depending on the LED, the current flow may change a little, just play with it until you get what you need.

Hope this helps.

This post has been edited by jlive: Sep 28, 2010 - 3:57 PM