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Even w/ proper driver circuit my laser diode fries

J

judogti

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wtf Im so lost on this. I bought a sony diode pre-installed in an Aixiz module. I ran it straight from a benchtop DC power supply @ 2.9v 220mA That one fried. So I buy another

This time I also purchase the Laser Diode Driver KIT (LM317T based) and a Sony Diode pre-installed in a Aixiz module. I ran this one from the Benchtop DC powersupply (9v @ .22mA) -> LM317T driver (reduces to 2.9v @ 220mA)-> Diode It ran for approx 1hour on time and BLAM fried.

This sucks! I built a great stencil laser cutter and it wont run for more than an hour. What am I doing wrong???
 





billg519

billg519

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Re: Even w/ proper driver circuit my laser diode f

This sounds nasty ! Do you have specs on the diodes? Are they safe and happy when run at 220 ma?
Maybe, assuming that you have yet another of these diodes available, you should start it out at 130 ma or so. Sometimes there can be an issue with ESD and ground paths through the bechtop supply. I myself use a benchtop supply for the testing of diodes, I don't lose any diodes to ESD yet, but I have lost a few to overcurrent. Try lowering your ma's. If diode OK, try maybe 175 ma. Try to run diode at lowest current that will serve your application. Also you may need more heatsink than just aixiz module.
Good luck, I'm sure you'll solve it.
 
C

chido

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Re: Even w/ proper driver circuit my laser diode f

The stonetek diodes should run ok at 220mA, what was your duty cycle? Were you using a heatsink?
 
J

judogti

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Re: Even w/ proper driver circuit my laser diode f

What do you mean by Duty Cycle?

Im using the Aixiz housing for a heatsink and then there is a metal clamp that is holding the Aixis housing so that it acting as a heatsink too.
 
C

chido

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Re: Even w/ proper driver circuit my laser diode f

Duty cycle means how long you kept the diode on and how long you kept off before turning it back on.
 
J

judogti

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Re: Even w/ proper driver circuit my laser diode f

chido said:
Duty cycle means how long you kept the diode on and how long you kept off before turning it back on.
Click to expand...
Ahh ok. With the second diode, I had it one for maybe 2 sessions of 15 minutes within 1 hour. Then today I had a maybe 3 5 minute sessions with a 5 minute break inbetween and then the last two where about 10 minutes with about 20 minutes inbetween.

So nothing rapid or close together, nothing that is pulsing. It's on 2D motor system, so once you turn it on, it goes for about 10-20 minutes and then its off for a while.
 
C

chido

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Re: Even w/ proper driver circuit my laser diode f

Well then no wonder it died, you're not supposed to run your diode at more than 1 minute without a proper heatsink. ;)
 
J

judogti

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Re: Even w/ proper driver circuit my laser diode f

chido said:
Well then no wonder it died, you're not supposed to run your diode at more than 1 minute without a proper heatsink. ;)
Click to expand...

Hmm, Ive read the Aixiz housing acts a good heatsink for these? Am I wrong? What are my options for heatsinks? Buy them anywhere? or do I have to make one?

Thanks for all the replies
 
C

chido

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Re: Even w/ proper driver circuit my laser diode f

They do act as a heatsink, but at that current you shouldn't drive the diode for too long unless you place the module in a heatsink. You can use a block of aluminum with a hole drilled through it. Just make sure it has a tight fit on the module, or get some thermal epoxy and glue the module in the hole.
 
J

judogti

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Re: Even w/ proper driver circuit my laser diode f

chido said:
They do act as a heatsink, but at that current you shouldn't drive the diode for too long unless you place the module in a heatsink. You can use a block of aluminum with a hole drilled through it. Just make sure it has a tight fit on the module, or get some thermal epoxy and glue the module in the hole.
Click to expand...

Ok I can manage that. How much surface area do I need? I need to keep it light so the stepper motors can move the laser smoothy. So the smaller the better but I obviously dont want to have too little like Im at now.
 
C

chido

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Re: Even w/ proper driver circuit my laser diode f

You decide the size, see how long you're going to keep the laser on and get something that keeps the module cool for that period of time. I don't suggest you let the module get past 90 degrees Fahrenheit.
 
roSSco

roSSco

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Re: Even w/ proper driver circuit my laser diode f

judogti said:
[quote author=chido link=1210472481/0#8 date=1210475338]They do act as a heatsink, but at that current you shouldn't drive the diode for too long unless you place the module in a heatsink. You can use a block of aluminum with a hole drilled through it. Just make sure it has a tight fit on the module, or get some thermal epoxy and glue the module in the hole.
Click to expand...

Ok I can manage that. How much surface area do I need? I need to keep it light so the stepper motors can move the laser smoothy. So the smaller the better but I obviously dont want to have too little like Im at now.[/quote]
Shouldn't the motors move the mirrors, not the laser? :-?
 
J

judogti

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Re: Even w/ proper driver circuit my laser diode f

chido said:
You decide the size, see how long you're going to keep the laser on and get something that keeps the module cool for that period of time. I don't suggest you let the module get past 90 degrees Fahrenheit.
Click to expand...


Thanks, very good info!
 
rog8811

rog8811

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Re: Even w/ proper driver circuit my laser diode f

If you go for a finned heatsink you get a lot of surface area for a smaller mass.


Regards rog8811
 
Zom-B

Zom-B

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Re: Even w/ proper driver circuit my laser diode f

judogti said:
Ok I can manage that. How much surface area do I need? I need to keep it light so the stepper motors can move the laser smoothy. So the smaller the better but I obviously dont want to have too little like Im at now.
Click to expand...
That's crazy. Moving the laser module is crazy. Search for 'scanner' on this forum to get an idea how it's done. People move very tiny mirrors on even smaller axles just to keep them as light as possible, and that way they can reposition up to several tens of thousand times per second.
 
T

thejunkmonger

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Re: Even w/ proper driver circuit my laser diode f

he's moving the laser to cut stencils,I have no idea if he is using a computer to control the movement or not. Using mirrors instead of moving the laser assembly would complicate the build of the stencil cutter way beyond the comprehension of most of us, not to mention a programming nightmare.
 
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