Any help on variable intensity LED's??

[camaroman]

Hey folks,

I am currently planning to make a set of LED boards for the taillights of my 1988 Iroc Camaro. I have some experience with LED's, mostly in model building. My question is this,... how do I make the LED's in the tail work at two intensitys? I.E..... when the headlights are on, they should glow at half intensity,... when I step on the brake pedal they should glow at full intensity. Are their special LED's I need to buy,... or what? Sorry for my ignorance here. Any help will be appreciated.

Thanks,

Jason

 

[Marduke]

They make replacement LED lamps for tail lights if that's your end goal.

Varying the brightness of LED's is usually accomplished by varying the current supplied to them.

:welcome:

 

[camaroman]

Thanks for the reply. I actually make replacement lenses, in clear and smoked colors. I'm looking to make a full board that goes behind each section of the lens with about 90 LED's in each section. I havent found anyone who makes replacement LED tails for the camaros, or I wouldn't be bothering.

The current to the LED's through the tails changed on its own when you step on the brake. How does that work with the resistors you have calculated to work with the LED's on your board? Do you just calculate for the high current of when the brakes are applied,... and the the lower current will automatically be dimmer because you wont be reaching the resistance point?

Thanks again in advance.

 

[Marduke]

The bulbs are fairly standard for different cars. You might want to look and see if what you want already exists here
http://www.dealextreme.com/products.dx/category.708

 

[MrGman]

The brake light is actually on a separate circuit. In a normal tail light bulb its a dual element bulb. The "running" lights are the 12W filament and the break light is a 25 watt filament that comes on separately when the brake pedal is engaged. They could be in one glass bulb or they could be separate bulbs depending on the car. You should already know this if you have worked on cars. JUst looking at a single tail light you should see two separate filament wires in the glass bulb and 2 sets of contacts on the bottom of the bulb and the brass base is the common return for both to chassis ground.

You could do the same thing with the LEDs. Have one module that comes on with the running lights power and then another set that comes one with the line for the power under the brake light control. If your not going to use drivers you could put a string of LED modules in series to the 12V line of each. A series resistor to limit the current flow would need to be selected to keep the LEDs within their normal power range or to make the running light unit dimmer than the brake light unit.

That requires knowing something about electronics and ohm's law.

 

[camaroman]

Thanks once again. I should have thought things through more. I know just what you mean with regards to the dual element inside the bulb now that I think about it. I think I know just what to do now. I just wasnt sure if there was an easier way around it. I have some experience with Ohms law, in my model building. See pics below.

 

[MrGman]

I really hate to break it to you Camaroman but that ain't no model of a camaro. That there is a tractor. Don't let the flashy red and white paint job full you. It is not a 396 RS SS.

Nice model. Good luck. :welcome:

 

[camaroman]

I really hate to break it to you Camaroman but that ain't no model of a camaro. That there is a tractor. Don't let the flashy red and white paint job full you. It is not a 396 RS SS.

Nice model. Good luck. :welcome:

Wow,... I am gonna have to go talk to that salesman. He assured me that it was a 1988 Iroc Z-28 at that. I thought the rear wheels seemed kind of agressive,... but I took his word for it :thinking: