dayle97se

Has anyone tried replacing the stock amber LED indicator bulb for the fog light switch with a brighter one? I want to replace it with a brighter one, since it's dim. The LED is rectangular and soldered in, but I can handle the soldering part.

Anyone know where I can a better/brighter LED that will fit? Need an exact bulb/part number.

I took apart my headlight/fog switch and will update this thread with pics tomorrow.

Cliff Harris

It's not supposed to be blindingly bright. It's just supposed to be bright enough to let you know that it's on.

There are millions of LEDs and without knowing the exact specs of the original one it would be virtually impossible to specify a replacement. Just for giggles, I went to my favorite electronic component web site, Digikey, and put "LED" in the search term box. For discrete parts you have 18,187 to choose from. Have fun:

http://www.digikey.com/product-searc...e/524729?k=LED

dayle97se

True, but I really can't tell if the LED is on during the day. I have to stare at it for a few seconds, which takes my eyes off the road for those few seconds.

If I were to remove the stock LED and give it to an electric supply company, think they could determine it's specs?

dayle97se

so i guess no one's ever done this mod.

Goldcylon

No and keep it in mind for night driving you would not want a blinding LED in the IP.

kg4fku

dayle97se - I feel your pain. I thought about the same thing when I got my 96. I plan to swap the LED out this winter when I do the rest of my upgrades to the dash. If you get to it before I do then please post what you find. If not I will do a write up this winter.

Cliff Harris

No. LEDs are not marked in any way. They do come in standard sizes, though. The only way to find out what you have is to take it apart and see what's in there.

You can change the brightness by changing the resistor value. LED brightness is directly proportional to current, which is determined by the resistor. The current must be limited by a resistor or the LED will burn up.

Annoyed

(small) Bulb part numbers

Air Conditioning/Heat Control.................37
Auto Transmission Indicator...................194NA
Courtesy-Door.................................... ..212-2
Dash cluster................................. ........882 (put 168 instead)
Flood-Door.................................... .......73 74
Glove Box..................................... .......194
Mirror-reading Lights.............................168
Mirror-Console Flood..............................74
SideMarkers............................. ............194
Spare tyre light................................... ..194
Visor Vanity Mirrors...............................74
Warning lamps................................... ..194


and you asked where to buy it from??

EBAY! ebay ebay ebay ebay!

Write "37 LED bulb" in the ebay search bar for example and you'll get a billion results and see pictures and dimensions and prices of the LEDs you're after, then have it delivered to your front door for peanuts.

Annoyed

This is what I don't understand. A lot of the LEDs are marked as "plug n play". I have installed LEDs without resistors and they've never blown.. but I do see where you're coming from and believe you. I take it the sellers don't care if you burn out your LEDs 400% or so quicker because at the end of the day you still "plugged and played" them (they worked when you installed them and they didn't blow + you don't keep track of how many hours they worked for before blowing).

I'll be getting one hundred 75ohm 1/4W resistors soon. Should I install one of them before all my small LED bulbs? How am I suppose to know/calculate if it's enough resistance or too much?

kg4fku

http://led.linear1.org/1led.wiz

or do a google search for LED calculator to find one you like (there are hundreds).

Not all LED are made the same. Some LED are designed to work with 12v (no added external resistance needed) while most are not. Most LED were (are) designed to work on low voltage input (TTL voltage level) and not operational voltage (9-36 volts DC).

Therefore, in order for us to use them in car applications, we have to use resistors to match the power requirements of the LED. Otherwise, the magic smoke will escape from the LED and afterwards it will refuse to work.

In other words, just buying a bunch of 75 ohm resistors isn't going to work out very well in your favor. You have to know the specifications of the LED you are working with as each type of LED has unique power requirements.

Cliff Harris

The LED voltage depends on the color. Most red LEDs are about 1.7 volts. Green and yellow LEDs are usually higher voltage. You calculate the resistor value based on the rated current. Most red LEDs are rated at 20mA = 0.020 amps, but they can go as high as 100mA = 0.10 amps. The calculation goes like this: R = (supply voltage - LED voltage)/current. You're calculating the voltage across the resistor and the resistance necessary to get that voltage.

One thing to watch for is the power rating of the resistor. If it's too low the resistor will burn up. Power = (voltage * voltage)/resistance. Usually you should use a resistor that is rated at twice the power that you calculate.

Be aware that 1/4 watt will burn your finger (about 140°), so keep the resistor away from things that can melt.

Many LEDs designed to replace incandescent bulbs in automotive applications have the resistors built in. LEDs are polarized and will not work if they are connected backwards. A lot of LED bulb replacements have diodes inside them to make them non-polarized.

Hot Rod Roy

When substituting LED's for incandescent bulbs in your dash, be aware that your dimmer control will not have the same range of brightness variability as with the incandescent bulbs.

Annoyed

Thanks guys. I'll look into it.
And fyi, I was referring to the typical LED car bulbs you can buy off ebay like the small 5-SMD 194 white wedge ones.
+ I didn't buy the 75ohm resistors for the LEDs... was just wondering if I can/should use them for my LEDs since I'm gonna have 99 resistors sitting around in my garage soon + figured I could hook up multiple ones in-line to get the right amount of resistance.

I think at this stage.. I'm not gonna bother with resistors for my LEDs. I'll see how long they last for first. They're only like $1 for a pair so I'd rather pay a buck than go through all these headaches of trying to calculate the right amount of resistance, then buying the resistors and wiring 'em up....

Annoyed

And trying to replace some regular bulbs - which can be controlled with the dimmer - with LEDs, won't work.
Like the Auto Transmission Indicator bulb.

Cliff Harris

LEDs have a minimum voltage lower than which they stop working. The usual way to dim LEDs is to use PWM (Pulse Width Modulation). Basically they flash the LED really fast so it looks like is on all the time. The dash back lighting uses this system. I wrote an article on this a while back:

http://forums.corvetteforum.com/c4-t...ull-story.html