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Topic: LEDs without the use of current limiting resistors (Read 5 times) previous topic - next topic

Hippynerd


You are saying its OK to pulse it at 100mA,  my manufacturer says 30mA  -   hmm .

Some TV remote controls use the internal resistance of the battery to limit the current through the IREDs, perhaps your running 192 LEDs from a couple of AA batteries is doing the same, how many LEDs are on at the same time ?

Whichever, its bad practice.

I run my 25mA rated LEDs at 18mA, and out of the last 25,000  LEDs since October,  I have had only a couple of failures, so I stick to that current.

I am pulsing the latest project ( 50% ) at 21 mA, still well inside of the recommended current.


I never said it was ok to pulse 100ma to anything, I described what I think the author of the document that the OP posted was trying to elaborate, but was unclear on how they made their calculations, I gave an example of made up numbers, and i clearly stated that I made the numbers up.

Your manufacturer is talking about "safe limits", most of the datasheets that I've looked over show LEDs at a 20ma max. I dont know how much current the LEDs Im using are running at, but they are running at 5V from wall wart USB battery chargers, one is 500ma, the other is 800ma. When both are  hooked up to a kill-a-watt, it shows 1 watt running both (it floats between 0 and 1) so my guess is it draws about 1/2 amp. I do know that the red LEDs are 1.8-2.2 VF) so 5v should be way too much for it.

I have another set that I have just completed, and I've run it from a 6 volt lantern battery, and from 4 AA batteries.

I have read that you can safely double the safe limit when using a duty cycle less than 50%, but I havnt done any testing with that. I have run 74hc595s way over their 70ma limit, for a few days without issue.

Grumpy_Mike

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I never said it was ok to pulse 100ma to anything,

So have you measured what you supposed good LEDs are actually taking?
There are two things getting damaged the LEDs and the electronics driving them.

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I dont know how much current the LEDs Im using are running at,

So how do you know you are not damaging things?

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I have read that you can safely double the safe limit when using a duty cycle less than 50%,

Safely doubling safe limits is an oxymoron. You can read all sorts of rubbish on the internet, it doesn't make it true.

I can only tell you what will work 100% of the time for 100% of the people. I know this because I have spent my whole life designing reliable electronics. Any idiot can design unreliable electronics that works for maybe two or three years. Or that works and significantly shortens the life of parts.

You can of course choose to ignore this, I can not stop you from being a total idiot. What I can do is point out that you are an idiot and point out why you are an idiot and why you are suffering from self delusions. Hopefully I can stop sensible people from following your idiotic total lack of logic.

1) You do not have enough equipment or expertise to know if you are damaging a component.
2) You appear not to know about peak current and power dissipation and how that relates to average current and average power dissipation.
3) You think that any activity that doesn't immediately kill you is a safe activity.

retrolefty

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3) You think that any activity that doesn't immediately kill you is a safe activity.


LOL, who first coined the phrase "That which does not kill us only makes us stronger" ?

Lefty

Hippynerd


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I never said it was ok to pulse 100ma to anything,

So have you measured what you supposed good LEDs are actually taking?
There are two things getting damaged the LEDs and the electronics driving them.

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I dont know how much current the LEDs Im using are running at,

So how do you know you are not damaging things?

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I have read that you can safely double the safe limit when using a duty cycle less than 50%,

Safely doubling safe limits is an oxymoron. You can read all sorts of rubbish on the internet, it doesn't make it true.

I can only tell you what will work 100% of the time for 100% of the people. I know this because I have spent my whole lave you measured what you supposed good LEDs are actually taking?
There are two things gife designing reliable electronics. Any idiot can design unreliable electronics that works for maybe two or three years. Or that works and significantly shortens the life of parts.

You can of course choose to ignore this, I can not stop you from being a total idiot. What I can do is point out that you are an idiot and point out why you are an idiot and why you are suffering from self delusions. Hopefully I can stop sensible people from following your idiotic total lack of logic.

1) You do not have enough equipment or expertise to know if you are damaging a component.
2) You appear not to know about peak current and power dissipation and how that relates to average current and average power dissipation.
3) You think that any activity that doesn't immediately kill you is a safe activity.


I havnt measured the current, but Im fairly confident that the arduino is delivering 5v, and I know that 5V is higher than the forward voltage, and *technically* should be doing damage. It should also be noted that LEDs wear, even when using them at the recommended specifications, they will eventually fail. so your statement about 100% of the people 100% of the time is 100% false.

1) false.
2) false.
3) false.

What is true, is that you *want* to call me an idiot, and make a lot of false statements to support your claims that im an idiot. Shame on you mike, you should not behave that way.

I hope you get over your cold or whatever.

Grumpy_Mike

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What is true, is that you *want* to call me an idiot,

I don't want to call you an idiot, it saddens me that when faced with the truth you can't see it.
That is my definition of an idiot.

So let's just look at one claim I made:-
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1) You do not have enough equipment or expertise to know if you are damaging a component.

You said this was false.
So you do have equipment and expertise to assess a damaged component!
If you truly have a decapsulating machine and a scanning electron microscope then please post the pictures of your driver output stage after 6 months of over driving an LED with out any form of current control.
If you do not have this equipment then what equipment do you have that can assess internal component damage?

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