How to check LED tint?

[tsl]

I have a couple (2) Cree XR-E Q3 5A LEDs on small boards. Is there any easy way to check the tint of these before installing them in a light?

 

[LukeA]

touch the contacts to 2 alkalines in series?

 

[Cemoi]

I have a couple (2) Cree XR-E Q3 5A

May I ask where you bought them?

 

[Gunner12]

You already have the tint bin(5A), so you should already know the tint. Maybe you can see how it matches with this?

 

[tsl]

touch the contacts to 2 alkalines in series?

Can you be more specific? I don't want to fry the emitter.

You already have the tint bin(5A), so you should already know the tint. Maybe you can see how it matches with this?

I have the emitter and I have studied the chart before, but I know that the tint can vary from brownish to yellow. I was looking for a way of checking the tint.

 

[LukeA]

Can you be more specific? I don't want to fry the emitter.

With two alkalines, you can't fry the LED. There's really not much to it. I use two D cells in a Radioshack holder. The current going though the LED from two alkalines will be less than it sees when it's installed, and so won't be nearly enough current to cause damage.

 

[tsl]

With two alkalines, you can't fry the LED. There's really not much to it. I use two D cells in a Radioshack holder. The current going though the LED from two alkalines will be less than it sees when it's installed, and so won't be nearly enough current to cause damage.

I could only find a 1D holder at Radio Shack. There were 2C holders ... would that work just as well? How about 2AA?

 

[AA6TZ]

I could only find a 1D holder at Radio Shack. There were 2C holders ... would that work just as well? How about 2AA?

tsl -- All of the batteries mentioned so far have been 1.5-vdc each. If you connect any 2 of them in series, you'd have 3-vdc available to connect your LED under test to. Though in no way critical in this particular application, the voltage drop across each battery would be, for all practical purposes, identical when connected in series using the same battery type [i.e., (2) AA's, (2) C's, or (2) D's]. Happily, pairing different types of batteries in your application, i.e., (1) C and (1) D, or (1) AA and (1) C in order to get 3-vdc wouldn't cause anything to "blow up" -- nor ruin your LED.:thumbsup:

-Clive

 

[tsl]

tsl -- All of the batteries mentioned so far have been 1.5-vdc each. If you connect any 2 of them in series, you'd have 3-vdc available to connect your LED under test to. Though in no way critical in this particular application, the voltage drop across each battery would be, for all practical purposes, identical when connected in series using the same battery type [i.e., (2) AA's, (2) C's, or (2) D's]. Happily, pairing different types of batteries in your application, i.e., (1) C and (1) D, or (1) AA and (1) C in order to get 3-vdc wouldn't cause anything to "blow up" -- nor ruin your LED.:thumbsup:

-Clive

So, the difference in battery type for this application is only capacity, not current? I wouldn't want to use 2 AA's and get a weak LED output when something larger would be more helpful.

 

[AA6TZ]

So, the difference in battery type for this application is only capacity, not current? I wouldn't want to use 2 AA's and get a weak LED output when something larger would be more helpful.

tsl -- Your stated task was to test the tint of an assortment of LEDs prior to installing them in your light. By using any (2) 1.5-vdc batteries in series, you should have sufficient voltage (and sufficient available current) to perform your tint testing.

That being said, I pretty much assumed (a no-no...) that all the batteries under consideration were fully charged, or nearly so. So, for sake of argument, let's SAY that each of the AA, C and D cells are "up to snuff", voltage-wise.

The available current from each of the series battery configurations previously mentioned should be more than adequate for your testing requirements, as you are only testing one LED at a time. When you begin to test more than one, i.e., multiple LEDs at a time, then you'll begin to run into trouble, due to the limited amount of available current. Paralleling series-battery configurations (for increased current availability) would become not only cumbersome, but counterproductive, as one could imagine. There are too many variables to delve into when attempting a thorough, all-encompassing discussion surrounding this topic, and this definitely isn't the place to do so, given the limited bandwidth constraints, not to mention quantum-levels of reader BOREDOM!!! :twothumbs

If you want to "do it right" (is there any other way? ), either use a (2) "D"-cell series configuration or, better yet, build/buy a 0-12 volt DC, regulated power supply (10-Amp or greater. More is almost always better, especially with bench power supplies. Variable current power supplies are more $$$) . . . and preferrably not the "wall-wart" type and a decent DVM (Digital Volt Meter -- Fluke is a good name to look for). Now you'll be equipped to perform a wide gamut of accurate testing, which includes, but is certainly not limited to LEDs.

My $0.02

Best of luck to you tsl. Please let us hear how you fared with your testing.

Cheers!

-Clive

 

[tsl]

Clive, thanks for taking the time to provide a thorough answer. Truly appreciated! :twothumbs

 

[AA6TZ]

Clive, thanks for taking the time to provide a thorough answer. Truly appreciated! :twothumbs

You're most welcome. It was my pleasure.

-Clive