How to get cheap White/Clear SMD LEDs

RGB Guy · January 5, 2020

I figured this out over the last month or so and I think it's pretty cool. It can be a bit dangerous so apply this information at your own risk.

So with people switching to LED light bulbs in place of incandescent/CFL, that means there is an increasing number of LED light bulbs heading for the trash. After investigating these light bulbs for some time and gathering some samples, I have discovered that I can get a 99% recovery rate of working white LEDs from these bulbs (the other 1% burned through my desoldering method so I can't say for sure). What I've found is that the power supply for the light bulb has failed in almost every instance. Kind of a shame so many of them just go to the landfill.

So if you want cheap SMD LEDs, just put the word out and collect LED light bulbs that are headed to the landfill. The head is difficult to get off (typically it's a plastic bulb glued onto a plastic shell so you just have to pry it off). The LEDs used in those bulbs are bright and CAN CAUSE PERMANENT VISION LOSS so wear your protection. There's also a capacitor inside that holds a HIGH VOLTAGE so also make sure you don't shock yourself. I now have a bowl which I'm filling up with clear/white LEDs.

mariushm · January 6, 2020

Usually it's not the power supply but one or several leds dead or dying that cause the led bulb to die.

One common fault is one or several leds going dead when reaching a certain temperature (the wire that connects the led die to the case disconnecting). As there's multiple leds in series , one led disconnecting causes all leds to fails.

Another common fault is one or several leds burning out and becoming shorted. This means the total voltage drop across all leds goes down and the current may go up.

Some power supplies monitor the voltage drop and current and they go outside some ranges, they stop working for various reasons (like safety, don't want to have a cascade failure killing all the other leds, or don't want ugly light output if too many leds are dead)

In a lot of cheap bulbs, the leds are overdriven (more current than rated) so after hundreds of hours of operations, the quality of the light is already sketchy... i guess if you don't care about light quality (color temperature, intensity etc) you can desolder such leds and use for various projects,

January 6, 2020

I figure it goes without saying that if you're desoldering LEDs from a broken device whose primary function is lighting, you shouldn't expect high quality long-lasting LEDs (there's a reason it's broken). But I have yet to find a dead one that hasn't been burned up by the solder blower.

Scheer · January 10, 2020

On 1/6/2020 at 5:23 PM, 7he404guy said:

I figure it goes without saying that if you're desoldering LEDs from a broken device whose primary function is lighting, you shouldn't expect high quality long-lasting LEDs (there's a reason it's broken). But I have yet to find a dead one that hasn't been burned up by the solder blower.

I think the LEDs from lights are probably some of the best LEDs you can get, its not worth the warranty hassle to have a bunch of LEDs fail so the spend the money on decent ones (unless you are buying the $1 LED bulbs). Power supplies failing are likely from bad power coming in and there isn't much protection you can build into something the size of a light bulb to keep them safe. I've had the same experience as you where the power supplies always fail leaving you with good LEDs, unfortunately most of mine are weird voltages like 32v or 56v. I assumed they would just be 5v or 12v, although I have found a few and just remove the whole PCB ring and hook up to a cheap 12v adapter.

mariushm · January 11, 2020

It really depends on the quality and price of the original bulb. Yeah companies can get huge discounts by ordering millions of leds to put inside lamps so you may get good leds for the price.

But, you can't be sure of the CRI and you can't be sure of how well the light is spread around the led.

I can order cheap white leds with <80 CRI which are ok for outdoor night lights or whatever but you won't catch me dead with such bulbs in the bathroom or at a makeup table (because low CRI alters colors) or I can also order 95+ CRI leds for a higher price.

You also get messed up color temperatures because sometimes the phosphorus is in the leds themselves, other times it's in the lens over the led or it's combination of leds and coating on plastic / glass to get the proper temperature.