Measure the LED

[chris0147]

Hi all,

I need your help as I am stuck and I dont know where to start. I have got four blue leds diode that come with dark blue led lights that I really want to get the same led colours for my 3 fans, but I have got no idea what the wavelength for that blue led lights.

I have attached the pictures for you to take a look.


I am not going to take out the LED diode yet until when I have been advice to do so. I think the wavelength is between 450nm to 470nm but I am not too sure. Do you know how I can find out what is the wavelength for that LEDS?

If you know how I can find out what wavelength for that blue leds, I would be very grateful for that useful information.

Thanks in advance

[janoc]

I have replied to your PM. Please, don't spam/PM your problems to random people. That's pretty rude, IMO. I also don't come to you demanding your help with fixing my car.

I am copying the PM reply here too so that others don't need to repeat the same thing.

Hi there,

I need your help as I am stuck and I dont know where to start. I have got four blue leds diode that come with dark blue led lights that I really want to get the same led colours for my 3 fans, but I have got no idea what the wavelength for that blue led lights.

Here is the pictures:

I am not going to take out the LED diode yet until when I have been advice to do so. I think the wavelength is between 450nm to 470nm but I am not too sure. Do you know how I can find out what is the wavelength for that LEDS?

If you know how I can find out what wavelength for that blue leds, I would be very grateful for that useful information.

Thanks in advance

I am not quite sure how did you figure out that I am the person to help you with this but let's try.

If you want to know the wavelength of a LED, you would need to measure its spectrum using something like a spectrometer:
https://en.wikipedia.org/wiki/Spectrometer

That is likely a massive overkill, though. If all you want is to make sure that the blue in you fans is the same blue for all of them, just buy a set of identical diodes from Digikey, Mouser or similar place. Don't buy cheap diodes from eBay or AliExpress for this - they will likely have much larger spread of parameters and they may not match each other. That's much easier than trying to match color with some random cheap diodes the fan manufacturer got that day from the Shenzen market.

However, if you absolutely do want to find diodes matching the blue of the ones you have already, then the only way I can think of of doing that would be to get your hands on a spectrometer and measure the ones you have. Then buy loads of diodes with a datasheet specified wavelength close to what you have already, measure those too and pick the ones matching the best to minimize the tolerances. Which is, in my opinion, a crazy thing to do for a bunch of fans - especially as the color will change with current, with temperature, when the diodes age, etc.