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A140 48 hour burn in test

blrock

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I decide to sacrifice one of my A140 diodes. I needed to know if they cope when under continuous operation for an extended period at highish amps. I read many threads of guys keeping the duty cycle short, then letting it cool down before powering on again.

The setup was simple. One diode glued into the heatsink and a fan keeping the driver and heatsink cool.

I powered on Thurday 16h30, current set to 1.3A. Time now is Saturday 16h30. 48 hours later.
Conclusion: Heatsink is still ice cold. I can touch within mm of the diode and everything is still cool. Absolute no signs of degradation. I was originally going to add a peltier cooler to the heatsink but I think this would have been an overkill.

BTW, it is winter in Johannesburg so the ambient temperature is between 6-23 degrees celsius. I'm sure the heatsink would have been a little warm if the ambient was higher.

Although I don't intentionally want to kill this diode I did volunteer it for sacrifice. I still have 23 more :)
Any ideas how I should push it? I don't have a laser power meter but I thought maybe going 2 amps or so for another continuous 48 hours ????
 

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oic0

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1.8 has been suggested as the highest long life limit so yeah, a test there or higher would be interesting.
 

hakzaw1

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Impressive- The S. Korean makers of these have made a truly robust diode.-and-+rep to you sir.
 

Meatball

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start one at 1.5A, another at 1.75A, and another at 2A. Run each of them for >25 Hours, and report back on any power degradations. Thanks for being willing to do science!
 

Tabish

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Wow that's just crazy. I used to think 1A was already in the "danger zone".

Now I'm regretting ordering that microboost @ 950ma.
 
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I decide to sacrifice one of my A140 diodes. I needed to know if they cope when under continuous operation for an extended period at highish amps. I read many threads of guys keeping the duty cycle short, then letting it cool down before powering on again.

The setup was simple. One diode glued into the heatsink and a fan keeping the driver and heatsink cool.

I powered on Thurday 16h30, current set to 1.3A. Time now is Saturday 16h30. 48 hours later.
Conclusion: Heatsink is still ice cold. I can touch within mm of the diode and everything is still cool. Absolute no signs of degradation. I was originally going to add a peltier cooler to the heatsink but I think this would have been an overkill.

BTW, it is winter in Johannesburg so the ambient temperature is between 6-23 degrees celsius. I'm sure the heatsink would have been a little warm if the ambient was higher.

Although I don't intentionally want to kill this diode I did volunteer it for sacrifice. I still have 23 more :)
Any ideas how I should push it? I don't have a laser power meter but I thought maybe going 2 amps or so for another continuous 48 hours ????
Try keeping the current the same, but cycle the power on/off with 20 seconds on and 20 seconds off and see if it'll pass this kind of test for 24-48 hours.
It's not difficult to make a simple timer circuit to cycle the power.
This would be a much more real life type test as most people will use them as pointers and be turning them on and off hundreds of times. It's also a good test to help determine actual lifetime as most of the stress is put on the diode with the initial inrush of current when turned on.
 

Benm

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I'm not sure the cycling test would make much of a difference - in the original projector they are PWM modulated to switching on and off continoulsy and a rapid rate.

Perhaps with a 20 second or one minute cycle time you do get a simulation of any thermal stresses (expanding and contracting materials) involved in use as a pointer, but to the laser chip itself switching it on and off doesnt matter.

Its really to bad you don't have a power meter though. With these long term tests there couldbe subtle degradation that you will not see - something like a 5 or 10 percent power drop at a given current.
 

Cyparagon

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most of the stress is put on the diode with the initial inrush of current when turned on.
So why aren't those DVD burners that are turned on and off hundreds of thousands of times a second all burned out already? And why then is pulsed power always rated higher?
 
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So why aren't those DVD burners that are turned on and off hundreds of thousands of times a second all burned out already? And why then is pulsed power always rated higher?
I believe he's referring to portables which are literally turned on and off very often. Pulsed laser diode circuits basically modulate the diode between a minimum and maximum current. Typically the minimum is well below threshold and the max is whatever the diodes max pulsed rating is, paying close attention to duty-cycle figures as well. Instantly going from zero current to 1.2A (in the case of these specific diodes) is believed to be harder on the diode than if the current instantly rises to 1.2A from 20mA or less.
 

LarryDFW

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blrock;

Good job on the 48 Hr. testing.

I would suggest continuing the test with just the heatsink, while montoring the heat rise.

Do you know the physical size of the heat sink and weight for reference.

That would give us a rough idea of the heat sink capability.

+1 rep for your work.

LarryDFW
 
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+1 for more data.
But without a meter, the only thing you will learn is if it goes LED.
Its still nice to have another data set for another diode!
 

.3lite

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Just keep at the same current, no more, no less, unless it dies, I hope it can survive quite long at 1.3A.
48 hours online at this point isn't very usefull for me, because I have only one diode and I would like to make lab module from it for laser shows etc. (so it will be running really long at 1A so I hope it will survive atleast 1000 hours).
 

blrock

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It's now running @ 1.45A. I'll leave it again overnight. It's still soccer crazy here in SA so I'm off now for a braai and to watch the playoffs. Will give you so updated info in the morning on the diode.
BTW, at 16 meters I could instantly feal the heat from the beam on the back of my hand. Quite impressive
 

Asherz

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Nice work! :)

I think I'm going to turn mine upto an amp from 650mA when I get a host sorted. Nice info, I'd say either leave it going and see how long it lasts at this current, or go upto 1.75 and see how long it lasts.

Cheers for the work!
 

.3lite

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It's now running @ 1.45A. I'll leave it again overnight. It's still soccer crazy here in SA so I'm off now for a braai and to watch the playoffs. Will give you so updated info in the morning on the diode.
BTW, at 16 meters I could instantly feal the heat from the beam on the back of my hand. Quite impressive
This is reckless, if you will increase current each day we won't be able to know at what point it dies, by testing diode you must stay at the same current level, it won't give any data AT ALL if it dies, there is no point in such action, it's just 24 hours which is nothing, diodes are meant to last at least 10 000 hours, so for example if it dies on 1.5A after 24 hours we will only know that it will be running for 24 hours at that current level and then die.

I suggest to run it at 1W output current, let's say it's 1A, so full test for a month (running 24/7/30) it will be 5040hours online, if it's survive, you will provide unbelievable usefull informations.

But since it's your diode, it's your call, I would like to do the same if I will get more diodes.
 




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