Red Alarm LED replacement?

Red Alarm LED replacement?

I have an alarm on my S and i was wondering if there was a way to change the red alarm light to a blue one. heres the one on ebay, but if they claim its only two wires, there must be something i can buy at a local store and avoid the shipping and stuff from ebay.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3034347221&category=14934

Its just an LED you can get them from pretty much any electronics supply store. You can get them from www.lumex.com they manufacture them. I put a super-bright (3500mcd) pure green LED behind the face of the clock. You can't see it at all unless its blinking. Its stealthy

Scott

LEDs come in different voltage ratings. Make sure you match it up with the one in there now, or poof...

You want to try and match the LED current as closely as you can.

any idea what the voltage is?

It doesn't really matter what the LED voltage is. LEDs are typically between 1.5V and 3V. The LED is being supplied using a 12V power supply. They put a resistor in series with the LED to "drop" the extra voltage accross, and that resistor also determines the amount of current that flows through the LED. It really doesn't matter what the voltage of the LED you put in is as long as its current rating is right. Let's say the stock LED is 1.5V @ 10mA. To get the current flow to be 10 mA they would put a 1050 ohm resistor in series ( (12V - 1.5V) / 0.01A ).

Now if you put in a 3V LED, you'll get a 9V drop accross the 1050 ohm resistor, which will give you a current of 0.0857A or 8.57mA ( 9V / 1050 ohm). That's close enough to 10mA.

You have to try and match the current of the LED and don't worry about the voltage. I don't know what the current of the stock LED is - you'll have to get an ammeter and check it out.

I tried measuring miy alarm LED output voltage with a DMM. The DMM could not respond quick enough and was jumping all over the place. So I tried a old analog meter, and it couldn't rise fast enough. So I yanked my o'scope out, it was 5V.

This in on a Viper (DEI) alarm system...the stock Toyota MAY be different. Perhaps you can hit the parts counter at Toyota, ask them to look the LED up, and see if it has the voltage on the despcription.


You could also just get a el-cheapo 12V LED, a 5V LED, and a 3.3V LED (most common values). Try the 12V first, if it doesn't light, go down to the 5V, then last the 3.3. Go with whichever lights bright without burning out. Then get your bright one in the same voltage. They're only like a buck a peice, even at Radio Shack.

alright cool, thanks for the info guys. i just thought it would be something different since my console is painted blue and my doors have the blue fabric on them, i might get the blue light. but it only turns on when the car is off.

but one tihng, if i try the 12v, 3v, and the 5v, if one of them burns out will it short circuit anything? cause i tried hooking up the winshield washer lights inside under the drivers side, and i blew a fuse. any idea on how to hook those up, i read here its almost as good as the neons just less light. and thats what i want, less light but just something that looks nice.

No, won't hurt anything, it'll just light REAL bright for a breif moment, then never again. It won't even get warm before it dies.

I should say, oxymoron is right...the ELEMENT (part that actually does the lighting inside the plastic bubble we call a LED) is 1.2v. But the LEDs you get from places like Radio ShacK (you've got questions, we've got blank stares) have the dropping resistor internal to them. That's how they end up with different input voltages.

Ah. I see. That's cheating!

intel61!

Actually, 03ToyMan raises a very good point. Can you measure the voltage accross the LED when it's on? That way you'll know if it has an integral resistor or not. If you measure 12 volts, go ahead and put in a "12 volt" LED - you won't blow anything.

oxymoron, that's nearly impossible without a oscillioscope. Digital meters won't respond fast enough, analog meters won't decay fast enough. I couldn't figure out a way to make the damn thing stop blinking and stay on! Aaargh!

Nothing a diode and a capacitor couldn't fix. Maybe the o'scope would be easier. Of course you could always use an analog voltmeter and a video camera.

alright guys, too much electrical data, jk. i'll try all three when i get time, i got school to keep up with. but if i try it, i'll post which one works exactly

or a meter with a "hold" button on it. That way it would hold the peak value.

I would assume the alarm box has an internal resister and is only outputting the 3V that the led needs. But do like they say and just put the 12V one in and then keep stepping it down till you have it as bright as you want, with no "poof"ing happening.

yeah, thats what mine had. I just removed the old LED and tested it to see how much voltage was needed to get it to light up. Mine is an aftermarket alarm though.

Scott

turns out that my local radio shack doesnt carry the 12v, and they were out of the blue 3.7v leds. they're about 3.00 a piece, so if they blow its a stupid 3.00 down the drain, but i'll try the 3.7 first, cause that seems like that likely choice.

Coincidence you just now posted. I have another window open, checking this out:

http://www.7volts.com/led_resistor.htm

Using this to figure out the proper value for a dropping resistor, you can use any LED you want.

Radio Shack does carry a 12V LED, but for some dumbass reason it's not in their on-line catalog, so the counter people will tell you they don't. Search the parts drawer, unless it's sold out you'll find it there. It is only a 5mm though, so it wouldn't be what you wanted anyways.

yea the guy said no, but i know they carry it too. should i just go ahead and buy the 3.7V and try that first? also it hooks up the same way the old one does right?

I'd give it a try. Just touch it very quickly to the wires. It won't blow that quickly. If it doesn't light at all, reverse which LED lead is on which wire. LEDs are polarity specific, if you hook it up backward it won't hurt itself or anything on the car, it just won't light.

I wish I had access to a factory alarm car so I could check this out!

aight will do, i need some time though, so it might be a day or a couple of days until i try it