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445nm LED'd?

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WastedEmu

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I've built a few lasers before and have never had one go on me (atleast until right now? lol)
i'm running the diode with an LM317, and a 1ohm resistor, and it isnt outputting very much light at all. the LM317 does get very very hot within seconds, could this be a problem?

i had this circuit, and diode working just fine a few hours ago and just turned it on again and this happened...
 





At 1.25A you need to heatsink-and-then-some both the driver and the diode.
What's the diode housed in?
I suppose your lm137 is "barenaked" so to say?
Does the diode start bright then goes dim within seconds?
What's your power source? Maybe the batteries are just low.

Oh, and welcome to the LPF!:wave:
 
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The LM317 has built-in thermal protection, so if it does overheat, it will cut output power to save itself. The heatsink on the laser diode is big enough to prevent the diode from overheating before the lm317 does, so i don't see a problem there, unless you somehow managed to install the diode or module without proper thermal contact.

I would get a new 317 and put a heatsink on it, and retry with the existing diode. Normally those 317s are darn hard to kill, but once in a while it does happen.
 
Well breadboards are notorious for unreliable contacts.
Do you have any capacitors in your circuit? If so where?
A capacitor on the output, parallel to the diode could blow it if the
contact were to be interrupted and reestablished, for example.

In any case, the lm317 is going into thermal protect at this current without a generous
chunk of metal attached to it.
 
i may have killed the lm317, i tried changeing the resistance to about 11 ohms to use it with one of the phr-803t LDs and nothing.

i don't have a capacitor in this circuit, the only 2 components are the LM317, and the resistor.

i can easily get more lm317's from my college, and this time I for sure will attach it to a heatsink from an old computer
 
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Benm said:
unless you somehow managed to install the diode or module without proper thermal contact.
Click to expand...

also, i don't know what you mean by that part of your response? i've never made a laser this powerful before
 
If You have the Diode pressed into the AixiZ module correctly you should have more than enough Thermal transfer, but if the Diode is not in correct using a bit of thermal grease before it was inserted would have helped.
 
i know i do have the diode pressed into the module correctly, i'll post a reply tomorrow after i get another LM317 just in case the one i have killed itself
 
alright, so today i got a new LM317, and attached a heat sink to it, i first started off by putting a phr-803t LD on it, and was able to light a match, with a 10 ohm resistor on it.

after that i disconnected the phr-803t LD and hooked the 445nm diode up to the circuit and was not getting nearly as much power as the phr-803t was getting, so i replaced the 10ohm resistor with a 1ohm, and there didn't seem to be a power increase in the beam. so from this i think i can confirm i somehow killed the 445nm LD
 
daguin said:
You have a "zombie."

-- cross referenced for others

http://laserpointerforums.com/f51/445nm-diode-leded-60566.html

Peace,
dave
Click to expand...

thanks for the reply

but do you know how this could have happened? I know i never left the soldering iron on the diode for too long, and i also don't have a capacitor in my circuit, i've never hooked it up backwards, or hooked it up to the circuit when it was already powered... I just want to make sure I don't waste another diode lol. and it is for a school project so I can't keep waiting for shipping time in between diodes

thanks
 
WastedEmu said:
thanks for the reply

but do you know how this could have happened? I know i never left the soldering iron on the diode for too long, and i also don't have a capacitor in my circuit, i've never hooked it up backwards, or hooked it up to the circuit when it was already powered... I just want to make sure I don't waste another diode lol. and it is for a school project so I can't keep waiting for shipping time in between diodes

thanks
Click to expand...

As I stated in the other thread, we are not sure what causes this (heat and ESD are suspects). There have been VERY few of them show up. Compared to reds and violets, these diodes are pretty tough.

It may even be original defect that just takes a bit to manifest. I've had one customer that had a diode turn zombie in a short time and I had one that was slowly degrading over time (that I replaced before it got to the zombie stage). Out of >600 diodes, that is a pretty good record.

However, despite the nice track record of these diodes, we ARE pushing them well above where they run in the projector. We are going to lose a few.

Peace,
dave
 
alright thanks for the help everyone who replied!

i have just ordered 3 more from DTR lol, so hopefully none of them go on me lol.

and one of my phr-803t LD's died on me in the same circuit at the same time, so i may have had it hooked up wrong, but so far on my other phr-803t LD everything is working smoothly after i rebuilt the circuit.

thanks again everyone!
 
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