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can cold "fry" a cheap red diode ?

BKarim

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1 month ago i bought a cheap keychain:
http://laserpointerforums.com/f52/fine-3-red-laser-flashlight-keychain-56438.html

it got suddenly very dim. i didn't expose it a high temperature, nor inverse the polarity, nor let it fall... i just let it 1 or 2 days at 10°C 50°F and when i tried to reuse it the laser was very dim (it doesn't seemed to reach full power even for 1/100 s).
the laser is now at normal temperature, the white LEDs are still working good.

do you know what happened ?
is it cold, or leakage current or voltage too high (that the was first time i powered it with a fresh alkaline for more than a few minutes)
 
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00Giorge

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Did you try changing the batteries?
50 degrees F is not that cold. How did you get the little degrees zeros?
 

BKarim

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sure i tried with fresh alkaline, fresh nimh...
but at reflection i think i had noticed the fading but i thought it was due to low bat.
so i putted a fresh alkaline and let the laser without testing it, hence the confusion...


it is frequent to see cheap red laser keychains fade out like this ?
i was planing to buy other keychain like this one for my friends...
 

LordKaramazov

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How did you get the little degrees zeros?
Off topic- Its his keyboard. My keyboard, as im from Portugal is an "International version" with all the accents(^~`´¨) and ç. His most prolly is an AZERTY one from france. Those are really wierd keyboards where u have to press shift+key to get a number...
So he has the º symbol...for example, and as in my language we also got ª and º, i can use it, for for example 2ª (that means second, feminin, in Portuguese).

For the degrees we just use what was supposed to be an 'o' instead of a degree sign. like 2º (second, masculine genre, in Portuguese).

U can also look for the ASCII code for it and use it like that.
 

CoherentRays

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How did you get the little degrees zeros?
It probably depends on your operating system. I'm running Windows XP Pro and I can find such characters by going to Start > All Programs > Accessories > System Tools > Character map. You can find all the characters you'd ever need there.

Ed
 

LordKaramazov

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Returning to topic. If the batteries are good and its still dim, it can be several things.

Either you used it a LOT! And as it was cheap it had a low "average life".
It can be an electric connection that was badly soldered, etc. and now the laser isnt getting enough Amps.
It could be due to a cheap driver (maybe the same one regulating the LED) that had some currents spikes, and with time it fried it.

There might be other causes...but i highly doubt it was the temperature. 10ºC isnt very cold. Normally laser diodes work in good conditions between -5º~0º to 30º~40º (to not push it very far).

Hope this helps
 

qumefox

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If it's a cheap red, just throw it away and replace it. For the price it's really not worth wasting any brain power on when they die. If fresh batteries didn't fix it, chunk it. Usually when I get cheap pointers like these i'll get a couple since it's inevitable one will die/get broken/get lost.
 

BKarim

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sorry Giorge i did not answer your question about little zero's cause i simply did not understood it :)
as said Karamazov the sign is on my french AZERTY keyboard.
you can get it too with "charmap"
there also must be some freeware that can reassign the caharacters on your keys
maybe you can find another qwerty charset built-in windows with this sign ?


is it frequent that a cheap laser dies quickly like this ?
was i unlucky or all the lasers of this model will die ?
(i was planing to buy more for my friends and family)


edit: when i look at the lens i can see a permanent thin red line. what does that mean ?
 
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00Giorge

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Ya I don't have that on my laptop just thought I might be missing it some where, thanks.

You might also try cleaning you contacts, the cooler temp may have caused some condensation and a little corrosion on the cotact points or threads.
Good luck.
 
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qumefox

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It's the typical cheap chinese laser crap shoot really. Out of the same batch you can get great ones and awful ones. If you really want something of quality that's guaranteed to hold up, your really going to have to buy something from one of the vendors that is known to have good quality, but usually higher cost goes along with better QC though.
 

BKarim

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but these good vendors do not sell keychains :(
what i liked in this one was that it has laser and white leds.
 

millirad

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No, unfortunately the keychain was probably not well built.

Thanks for the charmap info! v

My dog can beat up your dog..............

Ѭ
 

flogged

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Yes. LD's often run more efficiently at cold temperatures. If you're not using an APC (automatic power control) supply -- like most of the constant current supplies here.

The current required for the diode to reach a given power output tends to decrease with colder temperatures. So when you use the pointer in the cold this can kill the diode when using a constant current power supply or a resistor. This is especially true if the laser diode is being pushed over spec.

I've killed a few red diodes this way.
 




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