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I bought a pair of blue LED bulbs to replace the ones in the front and my dome light as well...I plugged them in the front and they work fine but the only problem is they always stay on when my car is running; they just stay very dim and sometimes flicker or one is dim and the other is completely off...anyone no why this is happening?...also before i installed my front ones and just had the LED dome light it would never completely turn off...it would dim and stay lit with very little light EVEN with my car off/....whats the deal here?>
thg6anks
 

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To fix this you'll need to add some resistors they are really cheap and easy to do but i don't know exactly what your lights looks like.

But LED's use a very low voltage to operate so that's why they stay on.

But i think if you have the dome switch set to off they wont come on but im sure you get them to turn on when the door opens:(
 

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I guess i didnt make any sence there

It takes more amperage to turn on a Surface mount/superflux LED then a regular 5mm Led

So if you get a bulb that says 10 LEds it could all be 5mm that take no power to turn on versus 5 SMT led wish need more amperage so there more resistence so they require more power/amperage.

So if you want the 5mm leds to work youll need to add resistence via resistor.

I took electronics for 3 years and dont know all of the exact terms LOL

unless someone else can explain it better cause thats the best i can do
 

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LEDs draw as much current as they are allowed. If they draw enough, they will illuminate. Generally the more current they draw the brighter they get. At a certain point in the consumption curve they will get very bright and then progressively dimmer. The more over-current allowed to flow, the faster they become dimmer. I've seen LED act light a single-use flash bulb (you weren't around when those were all the rage).

You don't have to use a resistor to limit the current drawn by an LED, but that is the most common way. You can also drive them with a Pulse Width Modulator, or a constant current source, or many other ways.

Finally, the package the LED comes in makes DIDDLY SQUAT difference how much current it draws. A surface mount LED draws no more or less current than the same device packaged in a 3 mm, 5mm, 10 mm, 45 inch, or any other package. The size of the size and composition of the substrate and doping material make the biggest difference in how much current the LED will require for maximum rated brightness.

~ MattInSoCal
Doing this electronics stuff for over 33 years
 

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So you would be the one to talk to about making a custom Led 3rd brake light.
Another project i am going to tackle. So expect a question in the next week.
If you're asking the 3rd brake light question of me, I'm booked solid until at least the end of July. I'll be out of the country next week, and two weeks after that, and three weeks after that, and so on. There's also the fact that I'm really not interested in designing your blinky thingy at this time, with a major part of that due to my having too many of my own projects that are on hold at the moment.

Besides, it's more fun to experiment. Google is your friend. There are plenty of sites around with information on creating LED clusters. Buy 100 or 1000 LEDs on eBay for $1.48 and play! What you don't burn up or use for your brake light you can scatter around the interior of your car. Put that three years of electronics education to use!

~ MattInSoCal
 
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