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What happens past 1.8A






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Drew

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the multi-mode 445 diodes start to dim out/die around 2 amps. 1.8 is the accepted max safe current to drive them at
 
rhd

rhd

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Drew said:
the multi-mode 445 diodes start to dim out/die around 2 amps. 1.8 is the accepted max safe current to drive them at
Click to expand...

Do we know this to be true of M140s, not just AXXXs ?
 
InfinitusEquitas

InfinitusEquitas

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rhd said:
Do we know this to be true of M140s, not just AXXXs ?
Click to expand...

No we don't unfortunately.

If there is such data, I would LOVE to see it... I'm sure I'm not the only one.

Also the results from m140's seem to be consistently better than they were with the a140s.
 
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lazeerer

lazeerer

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InfinitusEquitas said:
No we don't unfortunately.

If there is such data, I would LOVE to see it... I'm sure I'm not the only one.

Also the results from m140's seem to be consistently better than they were with the a140s.
Click to expand...


It does dim out the same. Iam not going to re attempt it as there is a chance of blowing the diode but i can tell you it does the same thing.

Not all do it at the same spot but for the most part it starts ~2050mW +/- 150mA.
 
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justinjja

justinjja

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is there a fair chance I Would be able to notice the dimming before it was too late?

Most electroncis can handle more current with cooler temps,
have these diodes been tested at freezing temps?
 
lazeerer

lazeerer

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justinjja said:
is there a fair chance I Would be able to notice the dimming before it was too late?

Most electroncis can handle more current with cooler temps,
have these diodes been tested at freezing temps?
Click to expand...

Well I dont know How long is too long for it to be to late.

All I did was turn the currant until it started dimming then quickly turned it back.

I did the same test DTR has done with the A140's:




Iam pretty sure he also tried this with the "M" 140 also.:)
 
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Drew

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lazeerer said:
It does dim out the same. Iam not going to re attempt it as there is a chance of blowing the diode but i can tell you it does the same thing.

Not all do it at the same spot but for the most part it starts ~2050mW +/- 150mA.
Click to expand...

Sounds about right :whistle::angel:
 
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geeo

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I've read a few threads on here that claim unless the LD is of above average efficiency it can die quickly even at 1.8A which led me to believe 1.6A was maybe a better limit?
 
123splat

123splat

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Simple question from an old fool,, why would the blue-violets be any different from reds in this respect? I have a match-box full of reds, gleened from various sources, that have been driven until they dim (then shut off within 3-4 seconds) without any sign of damage. I don't understand why over driving a 445 would cause damage (cod) but a red could survive the same process at a lower power (as long as you don't drive enough power to fuse any wiskers in the can).
 
BShanahan14rulz

BShanahan14rulz

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Anything will die if you mistreat it enough ;-)

Perhaps what you experienced was a result of the different materials that reds are made of. Reds are often GaAs based, while blues and violets and greens are GaN based. This relates to the cavity mirrors because the cavity mirrors are formed by cleaving the ends of the chip along a weak plane in the structure, much like how you can break glass by just scoring it on top. It all depends on how efficiently the OC passes or reflects light and how much is absorbed by the OC facet.

@geo, yes, that makes sense. As Cyp said earlier, COD is caused by too much light, not too much current. If your diode is more efficient, it is making more light per given current than other diodes, and will reach the damage threshold of the output facet at a lower current than other diodes.
 
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Benm

Benm

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BShanahan14rulz said:
@geo, yes, that makes sense. As Cyp said earlier, COD is caused by too much light, not too much current. If your diode is more efficient, it is making more light per given current than other diodes, and will reach the damage threshold of the output facet at a lower current than other diodes.
Click to expand...

While this is true, lowering the temperature may reduce the risk of optical damage to the output mirror facet. I suppose this would be related to absolute temperature though, so cooling from room temperature to freezing point would only make a 5-10% difference in maximum performance.

The again, i'd say pushing these dioes to 1.8 amps is enough torture as it is - they really were never designed to handle that much current and results will vary. Don't complain if you blow it up in 5 minutes ;)
 
BShanahan14rulz

BShanahan14rulz

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I think we should have just answered this with a friendly "Try it yourself and let us know." :eg:
 
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