Identify and replace LED

  • Thread starter chemaddict
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  • #1
chemaddict
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I am not an electrical engineer.

Ok, so I am interested in taking a cheap LED flashlight or headlamp (which I don't have yet) and identifying and replacing each individual LED bulb with an LED of a particular wavelength. I've seen you can buy LED's over the internet in bunches so that's no problem, but my question is this:

How difficult is it to 1) Identify the correct type of LED just by looking at it (e.g. voltage, size etc.) and 2) Replace it with a different wavelength LED of the same type.

More specifically, is there soldering involved? Are special tools needed? I don't even know how they connect LEDs to the circuit board.

I'm looking for an idea of difficulty before I get invested. Thanks for any advice.
 

Answers and Replies

  • #2
vk6kro
Science Advisor
4,081
40
That might be more difficult than you suspect.

Different colored LEDs operate at different voltages and flashlights and headlamps use switching power supplies (after the batteries) to generate voltages that are especially tailored for their exact LEDs.

So, if you put different LEDs in, especially different colored LEDs, you will upset all this careful design and the results would be unpredictable, but probably not good.

You can see a list of these different voltages here:
http://en.wikipedia.org/wiki/LED
under "colors and materials".
It is a good article and well worth reading.
 
  • #3
fss
1,182
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How difficult is it to 1) Identify the correct type of LED just by looking at it (e.g. voltage, size etc.)

Depends on the flashlight or headlamp. Some might give you "specs" you might be able to work with.

More specifically, is there soldering involved? Are special tools needed? I don't even know how they connect LEDs to the circuit board.

Probably. As an example, my recently-purchased LED MagLite has a single LED mounted on what appears to be a surface-mount circuit board smaller than the size of a euro penny. There doesn't seem to be a way to easily remove the board to get at the "circuitry." It runs of two AA (1.5 V) batteries.
 
  • #4
chemaddict
15
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Thanks for the replies. I do see that each of those different wavelength/color LEDs listed on wikipedia has a different voltage range. While some of them overlap, I agree that the results would be unpredictable at best.

That said, http://www.instructables.com/id/Infrared-LED-Flashlight/" website claims to do exactly what I was wondering about, and claims success in doing it. Maybe they got lucky.

Also, websites such as http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=/leds.htm" one that sell LEDs individually lead the consumer to think there are standard sizes and (in my my mind) standard voltages as well.

Thanks for you input, that was exactly what I was looking for.
 
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