8X Diode Murder fund

[bryce007]

I agree, I think the first should be set at 300mA. Then set the second diode depending on how long the first one lasted.

 

[Crazy Jay]

Igor;

Several board members have lost diodes @ 350ma.

The Sanyo 12X is speced for 200ma continuous.

Setting at 300ma is 50% higher !

Sounds like a good point to test at if you are looking for 100 hour lifetime.

Larry DFW

But wouldn't 200ma be the safety setting (without a doubt) for both good and bad diodes? I would think that 300ma would still be safe

 

[laze_doctor]

Good job everyone. I'm looking forward to seeing the results of this!

 

[HIMNL9]

@ IgorT: probably is better to make the tests for current, not for power, as you said, if for get the same power you need more current, it false the results for the ones that, after, you have to set in current.

After all, we have to manage them with current settings, for drivers, then get all the power we can at these current, so is probably better to have a graph about safe currents, so anyone can decide their driver settings with a common parameter

But wouldn't 200ma be the safety setting (without a doubt) for both good and bad diodes? I would think that 300ma would still be safe

But both bad and good diodes, probably, have the same electrical characteristics, also if they differ in output powers ..... and the degradation curve for overpowered LDs is exponential ..... if i had 2 diodes to fry p) probably i may want to give them different treatments ..... like, one starting from low mA and increasing for plot characteristics, and another putting it on a cycle like 10 seconds on / 30 seconds off, at the maximum acceptable power, and see what's the total life we can have, before it start to become weak (but this is just a personal idea, and anyway it's not the purpose of this serie of tests ..... maybe when 8X become cheap as PHR, can also be done this )

Anyway, for the exponential nature of the degradation, keep in mind that if at 200mA you get 500 hours of life, at 300 maybe you end with 20 or 30 hours (or 50 well heatsinked ?)

Are all suppositions, anyway ..... so, take them for the few that they worth


EDIT: I WAS IN ERROR, and the things are worse of that what i thought ..... the decay of the duration, for contitnuous usage of the diodes, overpowered, is an almost logarithmic function, not just exponential ..... i was taking in consideration just the decay of the material, but there is also to considerate the more quick increase of the temperature, the less dissipation, the fact that any modification of the reflective faces of the cavity keep more power in the crystal, and some other insignificant details like these ones ..... ah, well, brain foxilization, perhaps (or, maybe, i just need vacations ..... )

 

[LarryDFW]

Igor;

Several board members have lost 8X diodes @ 350ma
(electrostatic discharge may be a factor).

Both the 8X Sharp & Sony diodes are speced for 250mw pulsed power

These are probably the diodes we are testing.

Setting at 260ma is ~27% higher than the max. pulsed rating

Setting at 300ma is ~50% higher than this max. pulsed rating !

These are power and voltage levels for the power testing I did on Panasonic 8X diodes:

I (ma) Power(mw) Voltage

260 . . . . 318 . . . . 5.3
280 . . . . 344 . . . . 5.4
300 . . . . 376 . . . . 5.45

300ma & 50% higher power sounds like a good point to test at if you are looking for 100 hour lifetime.

Larry DFW

Note - Sony says pulsed maximum is 5VDC @ 320mw & 25° F for its 12X diodes

 

[HIMNL9]

Setting at 300ma is ~50% higher than this max. pulsed rating !

Yes, but the pulsed power given, is usually rated at 50% duty cycle, that means 200ma pulsed = 100mA CW ..... and this means using them at 300% of the CW given level (or 200% higher, if you prefer) .....

 

[IgorT]

I would like to see 300mA testing personally...

totally agree, these details are up to you, igor!
i said test the first diode at 400mW output, but your point is true. so lets see how much off the two lowest are, compared to the others?

Test current specific. The output will vary, but most of us set by current rather than output.

I agree, I think the first should be set at 300mA. Then set the second diode depending on how long the first one lasted.

Several board members have lost diodes @ 350ma.
...300mA... Sounds like a good point to test at if you are looking for 100 hour lifetime.
Larry DFW

Seems like we agree on current specific testing...
And it's true what Dave said, almost everyone sets their diode for a certain current, and then measure the power they got...

Setting for a power requires a plot first, and while we will have plots for diodes in this experiment, not many LPF members plot diodes before making a laser...

So let's test a current instead. See what happens, go from there...


Looks like we have our test protocol almost established... :yh:
The final adjustments (which current to test) mostly depends on the averages we find after all 13 diodes are tested...

The Sanyo 12X is speced for 200ma continuous.
Setting at 300ma is 50% higher !

200mA continuous? Do you have a datasheet or specs for it?


Otherwise, i can't help but wonder what diode is actually used in these first 12x's... We were all hoping for the 200/450mW Sanyo diode, but after seeing those charts you found, showing 300mW Pulsed for 12x diodes i'm "slightly" confused.. :thinking:

Especially, since it then shows 450mW Pulsed next to 300mW, as if both are meant for 12x speed instead of showing it higher up in the chart for a faster writing speed...

I mean, we know they need more power for faster writing speed at more layers, but I'd imagine if the first 12x's are made with a 150/300mW diode, that once the manufacturers get the 200/450mW Sanyo diode, they would also increase the single layer writing speed (like to 16x?), so their drive would seem better than the first 12x's instead of confusing their intended (and unintended) end buyers... :undecided:


On the other hand, we are already reaching powers i have expected from the 12x diode using 8x's..

If 12x's can make 500mW "reliable", i'll be more than happy.. :angel:

 

[IgorT]

Both the 8X Sharp & Sony diodes are speced for 250mw pulsed power

These are probably the diodes we are testing.

Sorry if i'm asking for info already posted elsewhere (except the threads i have open, i don't have time to read around much at the moment), but where did you get this info (diode manufacturer and specs)? Furthermore, are full datasheets available?

The only info i have is the chart you posted in your 12x thread, showing 240-250mW Pulsed for 8x's and 300mW Pulsed for 12x's..

Otherwise, the lower 8x requirement (240mW Pulsed) could also include Nichia's 120mW CW diode, for which there actually is a full datasheet available...

These are power and voltage levels for the power testing I did on Panasonic 8X diodes:

I just checked my plots, and your Panasonic diode seems close to the first LG 8x i plotted - the low efficiency one.. Does the diode from the Panasonic drive also look the same as LG and Pioneer?

Note - Sony says pulsed maximum is 5VDC @ 320mw & 25° F for its 12X diodes

This confirms that the first 12x's are using a 300mW Pulsed diode then... (Sanyo, Sanyo, lama sabachthani?)

But where did you read this? Again, sounds almost like info from a datasheet... Am i missing something? :thinking:

 

[IgorT]

But wouldn't 200ma be the safety setting (without a doubt) for both good and bad diodes? I would think that 300ma would still be safe

Before the editing, Larry was refering to the 200mW CW / 450mW Pulsed Sanyo diode, we used to expect from 12x BR writers... I am not sure if he meant it is rated for 200mW or 200mA continuous, but it's not the diode we are testing here, and from the latest data, it's not even the diode we will find in the 12x drives.

Here we are testing 8x diodes pushed to the powers i expected from overdriven 200/450mW Sanyo diodes!
The 8x's are rated for 120-125mW CW, while we are using them at 400mW+ CW!

To me this is a little scary, which is the whole reason i proposed this experiment here.
We are using them at over three times their rated power! In some cases even at over four times their ratings (500mW+)...


Looking back, we did push diodes to 3x their rated power with PHRs even at powers considered "reliable" (like ~120mW after plastic lens = 150mW after glass out of a 50mW CW diode - the PHRs most likelly rating), and other PHRs were pushed to 4x their rated power, but with drastically shortened lifetimes...

For some reason the same doesn't work with 6x's, they seem to remain reliable only to around 2.5x their rated CW power (= 100-105mW CW)... I have a freak that does close to 290mW at under 200mA, but it wouldn't live long if i were to set it to 400mW (it would probably pop instantly), even tho this should be the equivalent of setting an 8x to 500mW...

8x's on the other hand seem even more flexible than PHRs, unless it turns out that they don't outlive around 20h at 500mW. Some are dying in much less time than that..


405nm's are weird diodes.. I mean, i didn't even expect we would reach powers equivalent to reds this quickly, never mind higher!
But by the end of next week (or a few days later), Dave will probably show a picture of a 12x laser with twice the power of an open can red (if not more)!



I hope that everyone realizes that heat is going to start becoming an issue now... Even tho the currents we set them to are still lower than those of an open can, the forward voltage of 405nm diodes is almost twice that of reds!

This means at the same current, blu-rays produce almost twice as much heat as reds (1.8x as much to be accurate)!

 

[LarryDFW]

Igor;

This info on 8X and 12X is from the Sony web site:

Sony Global - Laser Diodes for BD Recording

Most likely, the 320mw pulsed power level is what is in the 1st 12X's.
It is 150mw continuous @ 140 ma.
I do think the 5VDC level is significant.

Sanyo also has a 350mw pulsed power level 12X BR diode.
It is also 150mw continuous output @ 135ma.

The Sanyo 450mw diode was shown in my earlier Sanyo links to be 200mw continuous @ 200ma:

LarryDFW

 

[Krutz]

[igor]
dont forget that this is the first time we just use diodes from working drives! they were all tested good and reliable before selling. with sleds, they may be spares, rejects, prototypes or known bad diodes, who knows.. and, if i'm not wrong, all other diodes ever used were from sleds, be it LOC, PHR, 4x, 6x, or the stranger ones which we couldnt even identify..


another thing many other people forget is that 16x DVD has nothing to do with 16x BR. the spindle speed and data transfer rate have nothing in common, the numbers just refer to the speed of the first commercial "1x" drives. cd and dvd both are at their spindle speed limits (i guess around 20k revolutions per minute), although its 52x with cds and 16x (or 24x) with dvds. we will never see 52x dvds, nor 52x BR. with a quick look at the spindle speed of a 1x BR drive we could guess what the maximum speed of BR will be. the media is almost unchanged, from CD to DVD to BR.
not referring to anyone special here, i just saw it mixed up a few times before..

manuel

 

[Crazy Jay]

Double the voltage. Multiple times the heat. These diodes are now the dominate ones on the market. Would it be correct to assume that the current hosts, sold on by members of this website, would not be suitable for these bluray's?

 

[Krutz]

well, we are still talking about a few watts only. there are three watts leds, overdriven to even more, in smaller hosts, with worse thermal contact. of course leds are a bit more sturdy too.. ;-)

as long as you dont hot-glue an aixiz module into your host, but use something comparable to the kryton or one of jay's kits, you're on the safe side!

..you still should leave some margin for different conditions, like cold host (higher current flow and more optical output and stress) or warm host (more stress on the diode, faster degration).

manuel

 

[LarryDFW]

Double the voltage. Multiple times the heat. These diodes are now the dominate ones on the market. Would it be correct to assume that the current hosts, sold on by members of this website, would not be suitable for these bluray's?

The hosts used by many ARE too small for the heat dissipation of these more powerful diodes.

I was running some tests tonight with a very large 14oz. host:

This host heatsink was too hot to touch after about 10 minutes of continuous run time dissipating 2 watts.

LarryDFW

 

[pseudolobster]

The hosts used by many ARE too small for the heat dissipation of these more powerful diodes.

I dunno.... I've run my 8x at 300mA for a solid two minutes without any noticeable temperature change in the heatsink (a jayrob "sidebutton" heatsink), it still felt cool to the touch... My LM1117T and its resistors, however, were far too hot to touch (granted, I was running it off 12v)... A SF-AW210 diode running at 200mA for a solid 60 seconds with no heatsink other than the aixiz head only started to get warm, not hot...
As far as I can tell, bluray diodes don't generate much heat. On the other hand, a 16x red diode running at 300mA, or a LPC-815 LOC running at 400mA tends to get really hot in under a minute.

 

[Crazy Jay]

The hosts used by many ARE too small for the heat dissipation of these more powerful diodes.

I was running some tests tonight with a very large 14oz. host:

This host heatsink was too hot to touch after about 10 minutes of continuous run time dissipating 2 watts.

LarryDFW

hmm I guess for the time being, we can't run these things long term without risking the actual diode itself. Maybe if the diodes where made with platinum they wouldn't need a heat sink but that would be far to expensive. The regulator on a cars exhaust system contains a platinum coating inside and my father told me it gets pretty hot in there (around a few thousand Degrees).