Lighting - Neons & LEDs
A) How do I wire 'x' in my car?
There are a few basics of electricity you need to know first. First things first - our cars run "12v" ("12v" because it's not really 12v, but whatever) DC. To keep things simple, we'll just say you need a 12v source ("hot") and a ground point ("cold"). Your 12v source is positive (typically red wire, or the lighter-colored wire), and your ground point is negative (typically black wire, or the darker-colored wire). Never allow a hot wire to directly touch a cold wire, or a metal surface - it will short.
Getting power to your accessories is the first step. You have to decide how you want to do it. The most straightforward method is to run a wire directly from your car battery into your interior (make sure to put an inline fuse in it - 15a works well). Others decide to tap into wires in the fuse panel - the cigarette lighter is an oft-used source. Whatever you tap into, make sure the wire is hot. This is now your 12v source. Now you have to find a ground. A ground is anywhere that electricity can flow to after it's passed through your accessory - ground wires can be tapped into, or you can find a ground in your car (I suggest this). An excellent ground point is any of the four places that your center console bolts to. Run your ground wire there, and use a wire terminal to connect it.
You now have a 12v source and a ground point. ... so? Well, with these you can now splice them all you want, and route them to different accessories/switches in your car.
B) Wonderful! But you didn't answer my question. How do I wire 'x' in my car?
You're right, I didn't answer your question - but the previous answer gave you nearly everything you need... watch.
i) Switches: These come in two common flavors: two lead and three lead. Two lead is just an interrupt - connect your 12v source to one lead, and then connect the other lead ("Acc.") to the positive wire of your accessory. Three lead is an interrupt with a ground - these leads are labeled Ground, Acc., and Source (or Power). Connect "Ground" to your ground point, "Acc." to the positive wire of your accessory, and the "Source/Power" to your 12v source.
ii) Neons: Connect your 12v source to the positive wire of your neon. If there's a switch between your 12v source and your neon, follow instructions in 2.B.i. Connect the ground wire of your neon to your ground point. Easy eh? Mounting neons isn't bad either. Zip-ties work really well for this!
iii) LEDs: Ok this is a bit trickier. There are two ways to wire LEDs - in series, or in parallel. This can get complicated though - typically, LEDs need only (approximately) 3v (you can get LEDs for real cheap at LSDiodes∞). This creates a problem because our cars run 12v, remember?
a) Instructions for wiring in Parallel:
You need to put a resistor on your LEDs, otherwise you will fry them by supplying too much voltage. Our cars put out 12v, but most LEDs take anywhere from 2.3v to 4v. If you get your LEDs at LSDiodes∞, they have a spec sheet for each of their LEDs. Using Ohm's law, R = V/I (resistance = voltage/current), you can determine the amount of resistance you need.
If you're wiring a single red LED from LSDiodes∞, you'll need to supply 2.5v for 20 milliAmps of current, to get the brightest glow possible. Since we're wiring in parallel, you use Ohm's law for one LED:
R = (12v - 2.5v)/.02A
Ok, that's probably a little confusing. 12v is our supply voltage, obviously. The 2.5v is the drop across our LED. That results in 9.5v left that need to be accounted for. The .02A is our current (20mA converts to .02A). This leaves us with 475v/A, or 475ohms. 470ohm is the closest resistor, get it!
Note: The resistor you need depends on the LED you get and how bright you want it to be!! If you purchase LSDiodes∞ 5mm, white 12000mcd LEDs and you want them to be as bright as possible, then you need to supply 4v with a current of 25mA. Ohm's law strikes again:
R = (12v - 4v)/.025A leaves us with 320ohms. So you need a 320ohm resistor.
Now you need to solder a resistor to a lead (I choose the positive (longer) lead, just because) of each and every one of your LEDs, like in the following picture:
If you're going to put multiple LEDs on a single 12v source, follow the below diagram to wire them (only four shown below, but this can be used for as many LEDs as you like!). Notice that you have a resistor for each and every LED. This is necessary if and only if you're using 1/4 watt resistors... I'm not going to go into details, but if you know what I'm talking about then you know you can use only one resistor if you use the right one.
That's wiring in parallel. Note that you can add or remove as many LEDs as you like, without worrying about adding a new resistor.
b) Instructions for wiring in Series:
Wiring in series involves less work than wiring in parallel. Take wire and lead it to the positive lead of an LED, then connect the negative lead of that same LED to the positive lead of another LED using wire. Continue as necessary.
One problem. If you're using 2.5v LEDs, Ohm's law states you can only wire up four LEDs. If you're using 4v (like the white LEDs), only three. Example: four red LEDs in a series
R = (12v - (4*2.5v))/.02A
Note that we have more of a voltage drop than we do in parallel. That's because each LED adds to the voltage drop across the entire circuit. Resistance here is calculated to be 100 ohms.
The differences between series & parallel should be pretty clear now. Note that you can always wire a few series in parallel, or whatever you need to do to get your LEDs wired up. I typically choose in parallel because I don't have to worry about needing to change resistors if say, I want to add one LED to a circuit.
So, to answer the question.. how to wire LEDs? Pick a method above. Once you have an assembly, mount it in your car, and connect the 12v source & ground point to the positive and negative wires you have for your LEDs. Pretty simple eh?
iv) Other 12v accessories:
Simply connect your 12v source to the positive wire of the acc., and the ground point to the negative. It's all really this simple once you have your 12v source & ground point!
3. I hooked up my LEDs in parallel, but some of them aren't lighting up. What's wrong?
Chances are you've mixed voltages with your LEDs. Electricity will always take the path of least resistance. For example, if you have two red LED (2.5v) wired in parallel with a white LED (4v), then the white LED obviously requires slightly more power. Due to this fact, the electricity will flow to the red LEDs and that's it. In order to resolve this problem, you'll need to make sure that each LED is going to get the right amount of current flowing to it. Since the red LED takes a max current of 20mA, you need to bring the white LED to that same current.
R = (12v - 4v)/.02A = 400 ohms. Picking the next highest rated resistor will give you what you need (it's 470 ohm, so this is a bad example. whatever)
The Following Is 3rd Gen Specific!
Looking for a power lead for lighting in your door panels? Look no further...
- Steve wrote:
- Hey guys,
- I was playing around inside my doors and have some new info for you.
- On the 03-04 Cavs, you can wire LEDs using the leads in your power door locks.
- Wire your Ground to the White Door Lock Wire
- Wire your hot to your Orange Door Lock Wire
- Not only does this light the LED, but they blink when you lock and unlock the doors! Adding an optional switch should be no prob.
- I had asked Raptor about this recently but just now got down to posting which wires to use for which. Hope this helps somebody out there!
- -Steve
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