SparkFun Forums

[cubangt]

So at this moment I have most of my LED's in the original manufacturers packaging, so it has the labels on the side showing what they are and so on..

But it seems that at some point, some have fallen out of the packaging, so is there any way to determine what they are and so on as far as forward voltage? is that something that can be done with a multimeter?

[monkeyxpress]

Get a 1k resistor and a 9V battery and wire them up in series with each LED. Sorry this sounds so obvious, but it is really the best way. Some multi-meters have an LED test function and this is all they are doing inside.

Beyond identifying the colour you'll have to use your eyes to determine whether they are high intensity LEDs or regular.

Each of the colours has a well defined forward voltage characteristic (set by the physics that determines the colour) so there isn't that much need to measure each on individually once you know the colour.

[Ross Robotics]

I use a variable voltage and current bench power supply. Usually start at 2V and go up until the LED comes on. I turn my current all the way up and when the LED is at full brightness, it will give me the current it's consuming. This also gives me the color and that will give you a baseline of the voltage drop and current rating.

[lyndon]

Continuity test on most meters will display the forward voltage during the check. I use it a lot when I drop a couple 0805 LEDs on the bench and I can't see the tiny tag that shows polarity.

[cubangt]

Well in my case, right now I only have 3 types of LEDs and color will help for sure since I only have 1 set of red and the other 2 sets are white.. so the whites are the ones im trying to get back into the right container cause one is 1.5v and the other is 3.2v or maybe the reds were the 1.5, either way, I do have 2 sets of whites that are different..

I have a variable power supply, so I can def try that method and for color I can simply use the battery method..

thanks everyone..

[lyndon]

If your variable supply has a voltmeter, then set it for a 10mA current and connect to LED. LED will light up so you can see the color and the forward voltage will display on meter. Can do the same with the continuity tester I mentioned above. Usually there is enough current in that mode to light the LED.

[Mee_n_Mac]

I turn my current all the way up and when the LED is at full brightness, it will give me the current it's consuming.

Your vernier on the voltage must be a fine tune indeed! I know my shaky fingers would fry an LED. I can see it now ... 3.1v, not on ... 3.2v, barely on ... 3.3v, very bright and ... crap ...

[Ross Robotics]

I turn my current all the way up and when the LED is at full brightness, it will give me the current it's consuming.

Your vernier on the voltage must be a fine tune indeed! I know my shaky fingers would fry an LED. I can see it now ... 3.1v, not on ... 3.2v, barely on ... 3.3v, very bright and ... crap ...

lmao! I get hundredths of a volt and amp..

[Mee_n_Mac]

You must not drink as much as I.

http://youtu.be/Mzcgyk62cHU