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A140 48 hour burn in test

Nanolaser

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Thanks for sharing this precious information ! :beer:
 

krazer

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Just a reminder, the primary cause of 'death' of these diodes is a slow steady degradation in power, it takes a lot to get them to turn into a LED/DED like the diodes extracted from computers do.

This effect can be seen in my testing at 445nm laser diode
If you look on the long term graph at http://www.krazerlasers.com/lasers/445nm/diode-week.png
(note that the graph is 'backwards' the end it the test is at the left of the graph)
1. the more or less constant power on thursday/friday was with the current set at 1.5A and the diode mounting block at 30C
2. The current was increased to 2A saturday night, which caused a spike in power. The steady decline afterward was the diode slowly being damaged.
3. The logging software went nuts monday morning, and caused the graph to read a continuous 1.3w for a few hours
4. The problem was remedied and the current reduced to 1.5A again for the duration of the test, which ended tuesday just before the final dip in the graph which was when diode was shut off.
 

Tabish

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So it's safe to say that, these diodes can handle up to 1.4A safely with proper heatsinking and short duty cycle ? Like 20s ON / 20s OFF
(Although the diode life might suffer...)
 
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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.
I agree. Knowing how long the diode can survive at 1W would be more helpful.
 
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I agree with the long term testing stuff, but keep in mind that he does not have a LPM.
He will only know if it changes a lot.
 

oic0

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Doesnt the thing run at around or over 1amp in the projector? why would it live a shorter life at the same power taken out of the projector and given better cooling? :thinking:
 
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Doesnt the thing run at around or over 1amp in the projector? why would it live a shorter life at the same power taken out of the projector and given better cooling? :thinking:
Because they are run pulsed in the projector and we are running them with a constant power supply.
 

blrock

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I turned the laser off this morning after about 84 hours. The last 36 hours the diode ran @ 1.4 amps. As you know I dont have a LPM so I guesstimated the output by "feeling" the heat on my hand. I'd be very surprised if the output did drop substantially because it still burnt the crap out of me. Of coarse there is no way I could tell if it did drop 10 percent.
So....I'm going to lock the laser in the cupboard tonight, setting the current to 1 amp. I'll leave it for the month.
Stay tuned

Off topic: I'm ordering a PBS for $50 coated 400-600nm from Crylight.com Going to combined two laser and hopefully get about 2+ watts out. Does the price sound about right?
 

Tabish

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WAIT!!!! Don't do that now. The fact that you drove this diode at well over 1A kinda ruined the experiment. For testing @ 1A for a month+, start with a fresh diode imho.

I think its better to leave this running at about 1.4A and see how long it lasts.

Reason: HIMNL9 found that these diodes are being driven at 1.84A @ 80% duty cycle pulsed. This translates to 1.47A CW.

I think 1.4A CW is probably the highest "safe" current. Also, you already took this diode to 1.4A so it shouldn't affect the experiment.
 
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This is your experiment.

If someone wants you to drive the diode to their specs , let them drive their own.

Drive it to what you want to , record the progress...
 

Ushan

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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.
woud this be why the sanwu lasers have a kind of "soft start" to them?(like it takes a good second to power up fully) and sorry if i bump and old thread, im finding random threads i like :D
 

Richie89

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Are you freaking kidding me!!? Damn it I didn't realize this was an old thread!!! I'm not mad at you Ushan
I'm mad at myself for not realizing it was 7 years old!!
 

Ushan

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Are you freaking kidding me!!? Damn it I didn't realize this was an old thread!!! I'm not mad at you Ushan
I'm mad at myself for not realizing it was 7 years old!!
LOL, i was just sitting here realizing the same thing. 7 years old..... way to gravedig (not you, but me) xD but i had an honest question!
 
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