Installing LEDs in dash

I was thinking of installing LEDs in the dash since the bulbs aren't bright and yellowish...

Anyways im new to this and don't know if my plan will work.

My original plan is to buy some wire, LEDs and a switch from radioshack. Then soldering the LEDs to the wire and stick them in where I want them to be.

But I think that the LEDs will blow cause of the 12v power. Is there a specific LEDs I have to buy or add something else so they won't blow from the 12v power?

thanx for any help

 

use a ballast resister to limit current. You can get LED's for 12 volts. Size your resister to limit the current to about 50% of the rated maximum of the LED. These will be in the milliamp range normally. So you want a 300 ohm or larger resister to limit the current. voltage= Current * Resistance so Voltage deivided by resistance will give you a maximum current. (I=V/R) So at 12 volts/300 Ohms=.036 Amps or 36 milliamps. You can adjust that resister to make the bulb brighter or dimmer to your preference.

 

You need to put a current limiting resistor in series with your LEDs. Pick a resistor that will give you 10-20 mA of current.

Ohm's law: V/I = R, so 12v/0.01A = 1200 ohms. 1000 ohms will do fine, and is available at the Shaque. Calculate the power dissipation too: P = IV or 12*0.01 = 0.12 watts. Always use a resistor at least twice the size of your expected power dissipation, so 1/4 watt or 1/2 watt at 1000 ohms will be fine.

LEDs are polar, so be sure to connect plus to plus, and minus to minus. Won't hurt anything if it's backwards, but it won't light either.

<edit> Heh. There's an echo in here!

 

The geeks are in the house. R)

 

Thought of this while rebuilding my dash. Here are a few places with LEDs adapted to auto bases for interior lights.

http://www.superbrightleds.com/led_prods.htm
or
http://www.lightlens.com/ledbulbs.htm?gclid=CJfXjsn1-48CFQSWHgodpjtkHA
or

http://www.ledshoponline.com/automotive_dashboard_bulb.htm

 

Thanx guys for the help...

I may have to copy some stuff down when I go to radioshack cause im a little confused but im sure the employees should know this...

 

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I wouldn't stake my life on that bet if I were you

 

Hear is a diagram to help you understand. This is how I wired my LED turn signal and high beam indicators when I built my new dash insert. In your case, you would just wire off the light switch. Unfortuntaly I do not have any pics of the LEDs installed as they are hidden by the dash wiring. The resistor values are what I started with and adjusted them to get the brightness I wanted. That value was very dim. So don't rely on that as being gospel.



For more information visit My Jeep Page and click on the Dash button at the top.

 

Thanx alot for this. This diagram and the pics on your site gave me a real good idea on how to do this...

 

I think I know how to install one led. But not sure about multiple leds

One LED would be:

Battery -> wire -> resistor -> + side of LED -> - side of LED -> ground wire -> car ground

By I want to install multiple LEDs. How would I do this? I have an idea on how.

Battery -> wire -> something that devides the power wire to multiple wires? And same thing with the ground?

thanx for any help

 

Im thinking it should be like this but I don't know what to use for that "???" if this is a correct way to do it...

BTW I just did this in Paint so no judging... lol



If this isn't a correct way of doing it can someone tell me what am I missing or doing wrong or missing. And if possible draw a picture or edit mine to help me understand it better...

thanx

 

The switch needs to be between the battery and the power buss for the LEDs. It should not go to ground. The way it is wired right now the LEDs will always be on and the switch will cause a direct short to ground when its turned on.

Move the switch and keep everything else the same and you should be good.

 

AS for the ??? you can either go buy some cheap bus bars at Rack Shack. Or daisy chain the positive electrodes together and the negative electrodes together. The second option makes it a royal pain to replace a burned out LED though. The Bus idea is a lot easier to replace parts when they fail.

Pic of bus. The bars on the left hand side distribute power and ground for all the guages in that panel. So you would need 2 of those. 1 for the power from the switch and one that is wired to a good ground.

 

Does each individual LED require its own resistor? Or can you go Battery-->Switch-->Resistor-->Buss Bar-->LED's (I know resistors are not too expensive, just curious. I don't know much about LED's.)

 

The short answer is, best practice is that each LED should have its own resistor.

Yes you can have a single resister to multiple LEDs. You have to use a smaller resistor because you will be dividing the current between multiple LEDs and need more amperage. But remember for every LED that burns out you are increasing the current to the other LEDs and will eventually cause them all to fail in that senario. A lot of the automotive bulb replacements are built this way.

 

Resistors are really cheap - no reason not to use a lot of them. Put the resistor inline with the wire to the LED and cover the whole thing with heat shrink tubing.

If you get serious about this, buy your parts from Mouser or Digikey. Radio Shack parts are cr*ppy, expensive, and a poor selection. Once you buy something from Mouser or Digikey, you'll get a catalog every few months. You might even develop an interest in electronics!

 

:iagree: What he said for parts source. They are cheaper and carry a MUCH larger selection. I am designing a digital control for Stop/Tail/Turn signals that will not care if you are running LEDs or regular bulbs. I will probalby get most of the parts through them.

Why? Because I can and It will make swapping a steering column very easy.

 

HUDSONHAWK and everyone else thanks alot for your help. You made this real easy for me, and gave me great knowledge on wiring. I already bought all the parts and will install over the weekend. Will post results and pics when finished...

 

Well like I said before, I got about everything already. But before I I start soldering and installing in the car. Im wondering what gauge wire should I use? Not sure if its determined with the how many LEDs im using (about 10 white LEDs)


And don't worry w3srl ill post pics of the wiring I did before I install and when installed...