anyone know the voltage of LED backlight laptop screens?, I have a project in mind Options

[match220]

I just replaced a friends laptop LCD screen and it has an LED backlight instead of the neon tube type backlight. I decided to disassemble the screen to pull out the LEDs to see what size they are and if I could probably use them in something else. They are the flat bright kind, and I'm thinking about rearranging them into a square pattern and putting them behind my dome light. I can't seem to find the voltage online, and I don't want to risk blowing them by guessing. I thought about wiring them into a radioshack universal power adapter that I cut the tip of a long time ago, that way I can slowly increase the voltage until they come on. But I still won't know the exact voltage they were made for.

Does anyone know what voltage they are supposed to be? Or at least approximately.

[Unicorn]

I just replaced a friends laptop LCD screen and it has an LED backlight instead of the neon tube type backlight. I decided to disassemble the screen to pull out the LEDs to see what size they are and if I could probably use them in something else. They are the flat bright kind, and I'm thinking about rearranging them into a square pattern and putting them behind my dome light. I can't seem to find the voltage online, and I don't want to risk blowing them by guessing. I thought about wiring them into a radioshack universal power adapter that I cut the tip of a long time ago, that way I can slowly increase the voltage until they come on. But I still won't know the exact voltage they were made for.

Does anyone know what voltage they are supposed to be? Or at least approximately.

Without sounding like too much of a nerd ( ) there's very little that I can't tell you about an LED or it's driver circuitry, but I'd need to see a pic of one of them first of all, so that I can determine the exact type of emitter that you're dealing with. If you want me to be general about it, you should be able to direct drive a SMT LED up to roughly 3.5-4v without doing damage, but a safe voltage would be 3v. If you are dealing with high intensity or high output LEDs, it's different - but since these came from a laptop LCD backlight I assume they are just standard SMDs, but I'd still like to see a pic of them so that I can tell you exactly what you're working with

Source(s); I'm an Electronic Engineer, but more importantly I design, build and collect/use high performance flashlights, most of which are LED based.

[match220]

Here's a picture, I can try to take a better one for you, but this is the best one that I could get. I'm cheap and my digital camera is about 5 years old, so it's autofocus and flash are starting to act up. I'm not sure if it matters, but one LED strip came from a gateway nv50a that I just worked on, which is the circuitboard type backlight. The other came from a toshiba satellite I think, which has the tan-ish brown flexible band instead of the circuitboard backlight.

picture of LED strips

I just replaced a friends laptop LCD screen and it has an LED backlight instead of the neon tube type backlight. I decided to disassemble the screen to pull out the LEDs to see what size they are and if I could probably use them in something else. They are the flat bright kind, and I'm thinking about rearranging them into a square pattern and putting them behind my dome light. I can't seem to find the voltage online, and I don't want to risk blowing them by guessing. I thought about wiring them into a radioshack universal power adapter that I cut the tip of a long time ago, that way I can slowly increase the voltage until they come on. But I still won't know the exact voltage they were made for.

Does anyone know what voltage they are supposed to be? Or at least approximately.

Without sounding like too much of a nerd ( ) there's very little that I can't tell you about an LED or it's driver circuitry, but I'd need to see a pic of one of them first of all, so that I can determine the exact type of emitter that you're dealing with. If you want me to be general about it, you should be able to direct drive a SMT LED up to roughly 3.5-4v without doing damage, but a safe voltage would be 3v. If you are dealing with high intensity or high output LEDs, it's different - but since these came from a laptop LCD backlight I assume they are just standard SMDs, but I'd still like to see a pic of them so that I can tell you exactly what you're working with

Source(s); I'm an Electronic Engineer, but more importantly I design, build and collect/use high performance flashlights, most of which are LED based.

[Unicorn]

Ah, judging from the trackpad/wrist rest that those were taken on, the Toshiba was a C6 series (C660?)? I've done some work on those new Satellite Pro models recently, really nice little laptops for the price. The LEDs seem to be fairly standard SMD types, I would assume a safe forward voltage of 3.5v and a maximum voltage of 4v for them. If you could get a macro image of the LED die itself, I should be able to tell you the actual brand of the die and look up what current it should be driven at. Again, a safe assumption for these would be a forward current of about 30-25mA.

[match220]

Ah, judging from the trackpad/wrist rest that those were taken on, the Toshiba was a C6 series (C660?)? I've done some work on those new Satellite Pro models recently, really nice little laptops for the price. The LEDs seem to be fairly standard SMD types, I would assume a safe forward voltage of 3.5v and a maximum voltage of 4v for them. If you could get a macro image of the LED die itself, I should be able to tell you the actual brand of the die and look up what current it should be driven at. Again, a safe assumption for these would be a forward current of about 30-25mA.

actually i lined them up on my laptop that I use, it's an Asus k52f. I just bought it a couple months ago. I work on laptops on the side and I just worked on one today. I think I remember the last LCD screen I did was LED backlit and was a toshiba, but I don't know for sure. The one I did today was the gateway. Here's a better picture.

[match220]

and if I want to cut these off and solder them on something that I choose instead of working with the tiny wire connections, can I just peel them off and resolder them to something else? I'm thinking I can just cut the tiny wire on the circuitboard that connects them and peel them off with a razorblade. It looks like they are only soldered on the sides, it doesn't look like they have pins sticking through the circuitboard. So I guess I can just peel them.

I need more LED backlit screens! LOL

[Unicorn]

Ah I see, the trackpad and wrist rest of your Asus look just like the newer Satellite Pro series.

Yes, you can just cut the tracks and peel them off and then solder them onto something. There are no pins on the underside of these LEDs, they are SMDs. That stands for Surface Mount Devices. What "dome light" are you hoping to solder them into?

[edit]

Just googled that, apparently it's an uncommon term (in the UK, anyway) for the interior cabin light in a vehicle... well for that there are other options apart from opening up more screens or bothering with desoldering and resoldering all those LEDs from the backlight strips - how about an LED conversion kit for it from ebay? They're not that expensive and come in a range of sizes:

http://www.ebay.co.uk/itm/Car-Interior-Lig...4-/230465463415

This post has been edited by Unicorn: Sep 20, 2011 - 9:50 AM

[match220]

I've actually been buying LEDs and citrcuitboards from china, I have 200 white 5mm LEDs that I got for about $15 with 200 resistors that drops the 12v from a car down to 3v for the LEDs, I have 100 yellow 5mm LEDs that are in the mail, and I've been buying cheap circuitboards, also from china. All together I think I've spent $30 on teh LEDs and circuitboards, but I would rather get free LEDs..lol. $30 isn't bad, free is just better. And I've seen the LED conversion kits, I have fun making stuff myself for cheap.

and yeah, dome light is what we americans call interior cabin lights, I thought everyone called it that. Dome light of the celica.

[Lantz]

I just replaced a friends laptop LCD screen and it has an LED backlight instead of the neon tube type backlight. I decided to disassemble the screen to pull out the LEDs to see what size they are and if I could probably use them in something else. They are the flat bright kind, and I'm thinking about rearranging them into a square pattern and putting them behind my dome light. I can't seem to find the voltage online, and I don't want to risk blowing them by guessing. I thought about wiring them into a radioshack universal power adapter that I cut the tip of a long time ago, that way I can slowly increase the voltage until they come on. But I still won't know the exact voltage they were made for.

Does anyone know what voltage they are supposed to be? Or at least approximately.

Without sounding like too much of a nerd ( ) there's very little that I can't tell you about an LED or it's driver circuitry, but I'd need to see a pic of one of them first of all, so that I can determine the exact type of emitter that you're dealing with. If you want me to be general about it, you should be able to direct drive a SMT LED up to roughly 3.5-4v without doing damage, but a safe voltage would be 3v. If you are dealing with high intensity or high output LEDs, it's different - but since these came from a laptop LCD backlight I assume they are just standard SMDs, but I'd still like to see a pic of them so that I can tell you exactly what you're working with

Source(s); I'm an Electronic Engineer, but more importantly I design, build and collect/use high performance flashlights, most of which are LED based.

Hey Unicorn!
A nerd is exactly what I need right now.
I have some backlight leds from a 42" LG TV
There are a total of 40 leds. (4 rows of 10.
The rows of 10 leds all plug in to a board at the top.
I didn't save the main circuit board from the TV and now I'm assuming I should have because of the power supply for the backlight.
My question is, can I just get some sort of power supply and get all the leds to light up?
I'm just wanting to make a really bright art project out of them.