8X Diode Murder fund

my opinion: the first one was set to a quite conservative current for an expected long surviving (which fortunately worked great). I would set the second one high(er), for the other fraction, who want much power at less runtime.
there are 12 diodes in francorob's list at 350mA up to 400mA. only two died altogether, one at 400mA from physical damage to the window, the other at 365mA for reasons i dont remember clearly. so these high currents dont seem to be *that* instantly deadly at all.

i would suggest 360mA, or at least 350mA.

Manuel

daguin said:

Igor is building the second cycler position now. He was looking at making two more positions but needed another part.

Peace,
dave

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Yep, i'm assembling the second sensor/counter setup, but for the 12x experiment..

The parts required are a counter and a GIANT heatsink. That, and a new sensor (which can easily be made out of parts i have on hand). I bought a second counter a while ago (after learning i'm torturing a 12x), now only the ModWerx heatsink has to come, and i can start that experiment (oh, and we have to decide where to torture the 12x - a very tough decision, in my oppinion...).


I could torture another diode blasting onto a sensor connected to a time recorder only (no counter (and visual feedback - to know when to replot)), but i didn't order a third giant heatsink... :undecided:



As for the currents, i'm already beating myself on the head, for saying "not necessary" to the third diode proposal on the second day of this murder fund. :yabbem:

I will go with whatever the majority of the contribuors wants of course. Might even sacrifice my own diode to answer some of the more complicated questions.

I just hope we don't go too high to get meaningful data this time.. If the result of the second test is 20h or less, that would be bad. It would mean we went too far, cos at those currents, diode life will vary from one to another as much as 1-20h..


Altho if the first murder candidate actually was the weakest diode (in more than just efficiency), there might be quite a bit more in them. We shall see..

And just this is a big reason for why i don't want to change the conditions of the first experiment! The final number of hours at 300mA will be VERY important in figuring out how much further we can push with the second one!


Anyway, attached is the second murder candidate..


P.S. The first diode is nearing 150h! Currently at 144h 33m! (only 385 cycles to go)

my vote is for 330mA. If we can get 50 hours of run time out of it, I'll be very happy

I'm with LarryDFW at 345mA or thereabouts.

I picked his number because he has graphs. :na:

I think that those who have contributed should have a say, but even more important, is Igor's gut feeling on this...

He has the most experience with these tests, and he is contributing the most with all his time and effort.

I would be nice if we could all agree to let Igor make the call...

jayrob said:

I think that those who have contributed should have a say, but even more important, is Igor's gut feeling on this...

He has the most experience with these tests, and he is contributing the most with all his time and effort.

I would be nice if we could all agree to let Igor make the call...

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I vote Igor too. Go people's republic of LPF!

My vote is for Igor too

igor definitely is the 405nm (as well as the torturing) authority on LPF!
what he thinks is good i think is good. when speaking about testing diodes, at least ;-)

manuel

Krutz said:

igor definitely is the 405nm (as well as the torturing) authority on LPF!
what he thinks is good i think is good. when speaking about testing diodes, at least ;-)

manuel

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Oh yeah, Igor is the dude who has his hands tied up constantly with work, but is always willing to fill you in on all your questions during his free time, no matter how confusing or complex his answers may sometime be

I think it's time to start the second 8x Murder experiment!

I was hoping to learn more about the entire degradation pattern (till COD) beforehand, but it looks like it would take too long to wait for this sucker to die!


The first murder candidate reached (and passed) 150 hours the night before last - stopped it at 9013 minutes ON-Time for replotting.

I should have mentioned it earlier, but i seem to have lost sense of time together with sleep... :yabbem:


At the start of this, i said i would consider a power setting reliable, if a diode survived 100-150h.

And i am completelly shocked that the first murder candidate wants to go even further! I was worried 300mA might be too much for these diodes, now i couldn't be happier i was wrong!


I knew we would be testing higher currents when the diode went beyond the 50h mark, but i had absolutelly no idea how much more they might be capable of (the question of what hurts them more - the current or the resulting power - is still open tho)!


I'm starting to think, that maybe, just maybe, we might get useful results at 340-360mA! :bowdown:



One question to 8x owners. Anyone, who has their 8x at 450 to 500mW... How much have you seen your power drop over time?

Dave: You said you kept track up to 20h with yours. What was the power at the start, and what was it after 20h (and what is it now)?

IgorT said:

One question to 8x owners. Anyone, who has their 8x at 450 to 500mW... How much have you seen your power drop over time?

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Im still at my same measurement of 564-565 .

Someone else asked this question earlier and no one answered so I'll ask it again. Which is harder on a diode, constant operation or pulsed? Igor said (correct me if I am mistaken) he thought it was the ON cycles that hurt it more, so running a diode for 100 hours in 1 minute cycles would degrade it more than 100 hours constantly. This would mean that pulsed operation would degrade it more, yes? But commercially they usually run them pulsed even when the device does not require it don't they?

This probably isn't a variable we want to change with second test, but it would be good to know for future tests. Any input is appreciated.

But they are rated @ 5000 hrs plus at their rated pulsed power. We are overdriving them at a constant power.

isnt pulsed power different than constant power though?

IgorT said:

I'm starting to think, that maybe, just maybe, we might get useful results at 340-360mA!

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Igor;

That's about 15% higher current than the diode that is still operating @ 150 hours (172% of original pulse power).

I think it would be an ideal operating point for comparison with ...
the 300ma diode power degradation.

LarryDFW

cappernicus said:

Someone else asked this question earlier and no one answered so I'll ask it again. Which is harder on a diode, constant operation or pulsed? Igor said (correct me if I am mistaken) he thought it was the ON cycles that hurt it more, so running a diode for 100 hours in 1 minute cycles would degrade it more than 100 hours constantly. This would mean that pulsed operation would degrade it more, yes? But commercially they usually run them pulsed even when the device does not require it don't they?

This probably isn't a variable we want to change with second test, but it would be good to know for future tests. Any input is appreciated.

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When diodes are pulsed, they pulse many times a second. They start cold and then the temperature gets up to a certain level and stays there the whole time the drive is working. Then it cools down when the drive is done working. That is really only one "complete" heating cycle.

When we use a laser the diode starts cold , heats up, and then cools back down again EACH time it is used. A laser that is pulsed is a different process than us turning it on and off.

IgorT said:

Dave: You said you kept track up to 20h with yours. What was the power at the start, and what was it after 20h (and what is it now)?

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It's got more than the 20 hours on it now. I just stopped keeping track of it then. It started out at 512mW. It is still putting out 505mW with fully charged batteries. I have lost ~7mW @ 365mA over 20+ hours.

Peace,
dave

IgorT said:

I'm starting to think, that maybe, just maybe, we might get useful results at 340-360mA! :bowdown:

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Thumbs up!!!

That's the info everyone wants.

By the time you finish this murder 8X drives wont be available anymore.