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3x 445nm LD PIV Plot

HIMNL9

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Those data are very close to the ones i'm collecting from the tests on one of my A140 diodes, (also if for now, my tests are mostly based on survival of the diode at constant current cycles for long times) .....

Anyway, there must be some differences of some sort, in the arrays ..... otherwise, it don't justify the fact that they have 2 different part numbers, on them ..... (maybe just cherry-picked, i agree with this too)

BTW, welcome back IgorT, glad to see that you feel better :beer:
 



lasersbee

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I'll be running another test a new A140 from Dave and two
A130 LDs from my projector next week (as soon as I can find
some time) and I'll post the Data here so you can add it to
your Graphs when it is done...

It does looks like my A140 is similar to your A130 LDs...
Well know more once my LDs are tested...

To get similar results I will start at Low Power and go up
by 100mW increments as before...
I know that the LDs will heat up as I get to the higher
powers but they will be in the same type Labby heatsink
as before..



Jerry
 
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daguin

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As for the duty-cycle question, i'll put it like that. As long as the head of the laser is not too hot to touch i am not worried. In the projector these diodes operated at 70°C if i'm not mistaken.
The thermal protection circuit in the projector is a 100C switch

Peace,
dave
 

HIMNL9

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The thermal protection circuit in the projector is a 100C switch

Peace,
dave
Right, but consider that this one is the emergency shutoff ..... inside the matrix there are other 2 NTC sensors (are these small SMD components placed on the first and last ribbon that connect the diodes, faced in the direction of the heatsink, and coupled thermally to the aluminium part with the 2 small pink silpads), that are used for measure the temperature in 2 different points of the heatsink ..... these keep an eye of the global temperature, and only if they fail, the safety thermal switch cut all off.

Unfortunately, there's no way for know what is the temperature at which the circuit is set ....
 

IgorT

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I'll be running another test a new A140 from Dave and two
A130 LDs from my projector next week (as soon as I can find
some time) and I'll post the Data here so you can add it to
your Graphs when it is done...
Thanks!

I like having multiplots available, as they are useful for determining the ranges of diode efficiency, and anyone can use them to figure out which efficiency category their diode falls in simply by tracing upwards from their current setting (or estimate what to expect beforehand)...


EDIT: P.S. Usually it kinda makes more sense to go in equal mA steps than in equal mW steps, cos current is what the Po is a function of in these plots..

Luckily i started making so called "Scatter Plots" a while back to allow accurate plotting from data which is all over the place, so it was relatively easy to insert your numbers into the multiplot.


I'll try to gather as many PI or PIV Plots as i possibly can and then put them into the original post here (obviously giving credit to those who contributed the data)...


There's one thing that bothers me tho. That diode of yours with an obscenely high Vf... I don't know what to make of it, as it drastically reduces that diode's absolute efficiency. It would be a good idea to include a diode like that in any torture testing to determine the absolute worst case scenario.

I really should try to extrapolate the in between Vf values to allow for accurate creation of minimum and maximum Vf boundaries and the average values.
 
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Traveller

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I also wanted to take this opportunity to show off my first 445nm laser ... It's in this wicked little stainless steel AA host wearing a 405-G-1 broadband coated lens ... The beast delivers 1190 mW from 1A of current when cold!
Welcome to the 445 club and talk about "making an entrance" with 1190mW... :beer:
 

IgorT

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Thank you for the great work! IgorT.

Your graphs are textbooks for me.:wave:
Thank you for your comments! Much appreciated! If it wasn't for all the feedback i doubt i would have the motivation to do it all.



And the explanation on test load is COOL.
I experienced two of 1.2W 445nm of 850mA v5.

I'm waiting drlava's v6 that could kill 445nm LD.
Wow, those must be some freak diodes you have there! The best of my three in the multi-plot needs 1A for 1.2W.. EDIT: Unless you did what i tried to explain in that warning and actually set them higher due to unmatching dummy Vf?


With v5 you are referring to the last FlexDrive version, yes?

I'm asking cos later you mention v6, which if i am not mistaken is not really FlexDrive v6 but MicroBoost v1. Don't confuse the two, they are completelly different beasts.

The MicroBoost is very close to what i've been using for over two years by now and made around 150+ of by hand, except that Lava's version is pot-adjustable (i only used fixed resistors) and has numerous safeties built in, to make it virtually fool-proof and user-friendly, which makes it suitable even for beginners to use as long as they follow the instructions... (my driver is much simpler in design as it was only made to work, and not necessarily to be friendly to anyone :evil:)


But in terms of their capabilities and limits they are almost the same, which is why i remembered to mention the warning for when a MicroBoost is used close to it's limits.



But i fear i didn't explain it well enough the first time and started going in circles, once i wanted to elaborate.

Let me try again:


VERY IMPORTANT FOR ACCURATE CURRENT SETTINGS ON THE MicroBoost DRIVER (TAKE 2):
If using a MicroBoost driver close to it's limits one HAS to do it with the dummy's Vf AS CLOSE AS POSSIBLE to the actual Vf of the diode (or a slightly lower dummy Vf just to be on the safe side!) while powering the driver from a PSU set to 4.2V (or a FRESHLY CHARGED battery if no PSU is available, but this is the less preferable option)!


The reason for this is, that when powered so close to it's limits, the driver can and will drop in current slightly (or even a lot) from where it is actually set to, as the battery voltage decreases (that's why i recommend using a PSU for this step) or if the voltage it has to put out increases (= if the Vf of the dummy is higher than that of the final load - the LD)....


In practice this means, that it is possible you unknowingly set the driver higher than intended, if you use an insufficient power supply or a dummy with too high a Vf - in both cases the driver may be struggling to put out your desired current and you actually end up setting it to 1.2A instead of 1A while you only see 1A flowing through your dummy load with a Vf of 5V (example). That's because the driver may be unable to push the current it's actually set to, through the dummy with a too high Vf.

Once you would then put this same driver onto an LD with a 4.5V Vf, the driver would suddenly be able to deliver the entire current it was set to, and pump it through the diode (which could potentially be dangerous depending on how big the difference is).

A similar thing could happen if you used a partially charged battery, forced the driver to push 1A through a 4.5V dummy, but then you put a freshly charged battery into the laser and the diode is suddenly at a higher current than you thought you set it to. That's why setting a driver from a PSU set to the very maximum a Li-Ion can produce is preferable...


I believe this explains the issue slightly better now... :angel:


The reason i am even mentioning this is because i've seen it happening a few times on my drivers and once on the MicroBoost when i was pushing them close to their limits.


But the issue manifests itself differently when the current is set by fixed resistors vs. a pot.

If you measure the driver's feedback voltage you can calculate precisely which resistors you need for 1A. If the driver then doesn't put out 1A through the dummy it can be either because the dummy Vf was too high or the supply voltage too low (or you're simply trying to run it over the limit). But since the fixed resistors set the current exactly to 1A, there is no danger once this driver is soldered to the diode - if it can, it will put out exactly the current it is set to and no more / if it can't the current will simply be lower than set on the LD which again isn't dangerous.

But when the same driver is adjustable with a pot, the user may not necessarily know what they actually set the driver to. If you're setting it too close to the limits you can run into the trouble i explained above.

Luckily these 445nm LDs are tough bastards and 1.2A instead of 1A won't necessarily hurt them (too badly)...


But still i believe it is best to be sure about where you have them set.

I will do some more tests to figure out where these limits i keep talking about actually are, but i can already say i really like the MicroBoost drivers. It's quite amazing how many parts Lava managed to put on there while keeping them small!
 
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IgorT

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Welcome to the 445 club and talk about "making an entrance" with 1190mW... :beer:
Thanks!

Why, is 1.19W a lot for these diodes? I was led to assume it's the norm while talking to some of our members here... :thinking:

But i have plans to design a "no duty cycle" laser that will be capable of powering these diodes at currents even higher than the drivers can deliver now (if it turns out to be "safe" for the diodes), and possibly with the added benefit of a VEEERY gentle start-up (can be made so slow you can actually see it getting gradually brighter, altho that is not required for diode safety), but there's still a lot of work ahead of me.


First i'm gonna order a number of 445nm diodes and most likelly torture one of them to death to determine just how far it is "safe" to go... By the time it's dead, the special new laser design should be ready... :evil:

I'm hoping ~1.5W+ will turn out to be just "reliable" enough...
 
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DrSid

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Yes .. interesting point .. did anyone actually burned this diode by high power ?
 

Prototype

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Only one person I know of, heruursciences, he took one to 2.6W raw diode output before it suffered from COD. It still lases, it's just very inefficient.
 

IgorT

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Only one person I know of, heruursciences, he took one to 2.6W raw diode output before it suffered from COD. It still lases, it's just very inefficient.
Oh noes... Not zombies again!

How do i train a machine to distinguish the living from the undead? :undecided:
 

DJNY

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You should open a thread for donating for 2 torture chamber diodes :evil:
 

HIMNL9

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How do i train a machine to distinguish the living from the undead? :undecided:
A dual thresholds measuring system ? .....

I mean, using a window comparator circuit ? ..... so, you can set it for the "good power", to exit an "ok" signal for continue the test, and a second power level, like, 15% or 20% less than the "good" one, for give a "zombified / too much damaged" signal for stop the test and signal it ?
 

IgorT

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You should open a thread for donating for 2 torture chamber diodes :evil:
No, i plan on buying a number of these diodes myself, torture one and once the end results are known i will accept donations for that one and possibly a second.
 

IgorT

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Those data are very close to the ones i'm collecting from the tests on one of my A140 diodes, (also if for now, my tests are mostly based on survival of the diode at constant current cycles for long times) .....

I'm preparing another "murder experiment" for these diodes, but i didn't get very far cos i was on vacation.

But once everything is up and running i'll start a testing thread, altho i won't be doing the many replots i did with the previous two. It's simply too much work - it'll be a simplified lifetime tests mostly just for the total lifetime.
 




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