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Discussion Starter · #1 ·
I am trying to hook up led bulbs to 12 volt and would really appreciate any info on how to do this,
 

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radio shack has prebuilt LEDs with plastic, nuts, washers, and resistor for 1.99. with all that said I can assume you could try finding the right resistor and LED color you want. Plus there are a few guys who have used LEDs in their headlights.
 

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Discussion Starter · #3 ·
I bought the led and resistor seperate but not sure how the resistors hook up to the led then to the wiring. I also work for radio shack and we dont have the leds set up for 12 volt that are blue only green and red
 

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run the postive and negative like normal, but set the resistor in series(run it in place of the wire) with the positive, the resistor will cut down ur current/or voltage, cant remeber for sure... 8O ..im in school right now for electrician..im still too slow to remember anything yet..lol, but this will cause ur LED to light...but dependign on where u want it and how u set a switch in with it or watever u wanna do...hope that helps.
 

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make sure you don't have the wrong resistor. but yes, run the resistor between the wire from the power source and the positive. if you go on ebay, they sell like, a package of 50 leds, and for $0.50 more you can get 50 of the correct resistors for about $11.00 total, the one i saw had free shipping
 

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Discussion Starter · #6 ·
so the resistor only goes to one of the leads off the led? thanks for all the help guys I really appreciate it.
 

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Discussion Starter · #7 ·
also witch one is the positive lead?
 

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all you need to know is:

V = I * R

where V = voltage (volts)
where I = current (amperes)
where R = resistance (ohms)

Just go here and read:
http://www.casemodgod.com/leds_and_modding.htm

After you're done, and if you still don't understand, just give me the recommended voltages of each of the LEDs and each of their resistances and I'll do the rest of the math and I'll tell you what to do. All of this stuff is explained in entry level physics books.

Here's a circuit I'm building for a fakey car alarm LED flasher... only it's night rider style... 20 LEDs, and they're going to go around the perimeter of the center console of the 3000GT. It's going to look really neat.
 

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Discussion Starter · #10 ·
ok so Im kind of getting the idea now. The flat side is the neg the other positive the resistor goes to the positive side. just so im sure I know if these are the right leds and resistors ill tell you witch ones that I have, well I have the 3.7 volt, 20ma,2600mcd, leds and the 220 ohm 1/2 watt, 5% tolerance resistors
 

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Discussion Starter · #12 ·
I am hooking up two with one resistor and I also would like to know witch led will work as a single unit with a resistor
 

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bluescort said:
I am hooking up two with one resistor and I also would like to know witch led will work as a single unit with a resistor
Well, either one will work well by itself, if they are both the same LEDs. But you didn't say you had two. You only mentioned one.
 

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Not to put you down or say you don't know what you are talking about but they do sell pre resistorized LEDs for 12v applications at Radio Shack. I bought some there not too long ago. They may not have them at your particular store, but I know they carry them. They were in the Pull out drawers with all the switches and capacitors and resistors and LEDs. They aren't the super bright ones, but the did already have resistors soldered onto them, and heat shrinked. I had to rig a new OD off switch for my truck, and I used a momentary contact switch and one of the red LEDs both from RS.
 

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Discussion Starter · #17 ·
Well our radio shack does have the 12 volt leds but not the blue like I wanted so I had to work with just the led and resistor
 

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http://linear1.org/ckts/led.php - Easy calculator.

If you hook the lights up in series, just add the voltages up, and the mA is the mean mA. If you hook them in parallel, then the voltage is the mean voltage of the LEDs.

Ex. If you hook up 3 LEDs (identical @ 3V and 20 mA) in Parallel, then the voltage needed is 3V and the amphere's (sp?) needed is 60 mA.

If you hook up the same 3 LEDs in series, then the voltage need is 9V, and the ampherage (sp?) needed is 20 mA.

bluescort, this should solve your problem.[/url]
 
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