How can I tell a LED is blown out?

On Sun, 16 Mar 2008 09:30:17 -0700 (PDT) in sci.electronics.design, Victory wrote,

Only if you can remove the plastic and examine it under a microscope.

Hope your battery was at least 3V, with a current limiting resistor.

Tam

Yes. As opposed to a test for a blown LED, it actually would create a blown LED every time.

You can hang a photo-diode/detector around there to give you an indication, or probably just as good an I-V detector, it's probably working if that's right...

If the LED got blown out by an extreme overload, such as applying 120 VAC, you would see the damage, but in most cases it is much more subtle. Actually, the Light Emitting Diode changes to a Darkness Emitting Diode, or DED :)

Usually an ohmmeter, especially in diode check mode, will provide just enough current to see some light, and it will conduct in the proper forward bias direction. But it may not work on LEDs with higher voltage, like blue and white varieties.

Paul

It's hard to tell if this is a high rel application or an incoming inspection requirement, I'm starting to "suss" it's the latter:-)

Crimany! The retarded word loyalty level in here is ridiculous.

They're just trying to make you feel like you're at 'the home', retard.

BTW, its VERY appropriate for 'dimbulb' to chime in on a thread about a dead LED. :)

Shouldn't that be a Darkness Using Diode?

Now I can see how people try to destroy a group by getting side tracked about some obscure word and avoids answering the question with an honest answer. There is no values with ignorance... The real answer about seeing a blown LED is to say that you need a microscope to see damage to the die or wires. How hard was that???????

Yag1064

Like he said...plus when a LED is transformed to a DED it will no longer emit any light regardless of being visible to the human eye's spectrum or not. Instead they usually tend to emit darkness across the entire spectrum. Maybe there is a way of modding a "darkness sensor" to measure the effect? regards, Joe.

That's called "visual inspection", and will only indicate a failed device if said failure was such that physical damage would be visible during said inspection.

We don't want to know what you have that is hard. Keep it to yourself. Just so you know, jacking off at the mouth about others "destroying a group" puts you in the same box, dipshit.

Then it would always be right.

Dip-Shit ya, your right. This group is called sci.electronics.design. I thought there was some knowledge to be gained. I see your point!! It's better to make fun of people than it is to help them. It seems a waste of a good resource for knowledge. Your command of the topic is pretty obvious. Good Luck to members of this group. I hope you are able to separate the wheat from the chaff.......

Not necessarily. Some failures might not be evident by a simple visual examination.

If it stops putting out light and/or it is no longer operating within specification electrically, its 'blown out'.

Yep. Even if it continues to act as a diode, if it is not putting out human visible spectrum photons in an appreciable quantity, it cannot be a Light Emitting Diode.

We are, of course,talking about standard LEDs.

So much for common sense.