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Need a better red diode for project.

I

irishluck

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Mar 5, 2012
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So I bought 10 of these ML101U29. They are 660nm 400mW diodes.

Unfortunately they only last about 2 weeks and they die.

The diodes are basically on for maybe 8-10 hours on at night.
I need a decent suitable laser diode for my project
maybe around $10 to $20 per diode that will last?
 





Any laser diode can last 5000 hours or even much longer unless it's overdriven or allowed to overheat. A laser of that power requires very good heat sinking and active cooling to be on for 10 hours at a time.

Alan
 
Pi R Squared said:
Any laser diode can last 5000 hours or even much longer unless it's overdriven or allowed to overheat. A laser of that power requires very good heat sinking and active cooling to be on for 10 hours at a time.

Alan
Click to expand...


But that doesn't make since. The driver is only set to .205mA. The diode module is cold to the touch. Doesn't heat up at all. I had it running for a week straight in my room to just test it and it never got hot....

We only had it set at 205mA for a 120mW. Never set it to use its full output potential.

Here is the data sheet for it.

http://www.glyn.de/data/glyn/media/doc/ML101U29.pdf
 
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Your right it doesn't make sense. From your first post I thought you may be running them at full power. You shouldn't be having this problem, it may be a problem with this diode not being able to run for long periods of time. Hopefully someone can suggest something better but I have doubts about $10-$20. I can't suggest anything myself, I have never tried to run red diodes in that power range for many hours at a time.

Alan
 
What driver? Could be runnin too many volts. Or have a harsh start
 
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Yea that my bad for not telling how much power I am running through it.

So its a 660nm 400mW ML101U29 Red laser diode. (I bought 10 for $30)

Its using an x-driver to power it only at .205mA.
Its not hot at all but still is properly heatsinked.

They run from 8-10 hours a night.

When they die out there basically just really dull. They arent completely stopping or anything just very little light.

When I test them out i make sure the driver is still at .205mA and they are.

10fenny Im using an x-driver
 
That is weird if its not getting hot. That diode must not want to run that long even with good heatsinking
 
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Ive seen that guy with that laser that has had it running for a long time.

Problem is that I just dont think its that powerful. I need it to reach almost 100 ft if not more.

Im also going to attach a picture of the setup im doing and you can see the heatsink. Its more than enough for what im using this for.
 

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Ive been trying to do some searching online just for places to find diodes.
Not having much luck.

Does anyone know of any good places to look for diodes? Any good brands?
 
From a read of the datasheet on that diode, it's only rated for 205ma as the max continuous current (not truly a 400mW diode, really more like 120-150mW - only achieves 400mw at a 35% duty cycle with some tens of nanoseconds pulse width) - it's also very much designed for low-duty-cycle operation as it's intended for use in a DVD burner.

I'm not hugely surprised it's only lasting a week or so in constant-on - that's probably around its useful lifetime at full power, as for the vast majority of the time it's in a DVD burner the diode will be doing very little, and it will pretty much never see full power.

If you're not particularly attached to 660nm you might have better luck with a higher power (400-700mW) constant-rated diode running at a lower current - one of the Mitsubishi 500mW diodes DTR sells ( https://sites.google.com/site/dtrlpf/home/diodes/mitsubishi-635nm-500mw-diodes ) may work, or the Oclaro HL6388MG 250mW diode ( https://sites.google.com/site/dtrlpf/home/diodes/oclaro-hl6388mg-250mw-638nm-diodes ) if you can't swing $34/diode - these diodes are intended for continuous operation (in projectors and other such high-duty-cycle applications) and so will likely last much longer, especially if not run at full power.

The Oclaro is also $25/piece in quantities of 5 from DTR, and he may have a further price break at 10 units if you PM him (depending on if you actually need that many)

Your logic in picking a 400mW diode to run at half-power for longer lifetimes was totally sound - you just didn't actually choose a 400mW diode :P
 
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anderp said:
From a read of the datasheet on that diode, it's only rated for 205ma as the max continuous current (not truly a 400mW diode, really more like 120-150mW - only achieves 400mw at a 35% duty cycle with some tens of nanoseconds pulse width) - it's also very much designed for low-duty-cycle operation as it's intended for use in a DVD burner.

I'm not hugely surprised it's only lasting a week or so in constant-on - that's probably around its useful lifetime at full power, as for the vast majority of the time it's in a DVD burner the diode will be doing very little, and it will pretty much never see full power.

If you're not particularly attached to 660nm you might have better luck with a higher power (400-700mW) constant-rated diode running at a lower current - one of the Mitsubishi 500mW diodes DTR sells ( https://sites.google.com/site/dtrlpf/home/diodes/mitsubishi-635nm-500mw-diodes ) may work, or the Oclaro HL6388MG 250mW diode ( https://sites.google.com/site/dtrlpf/home/diodes/oclaro-hl6388mg-250mw-638nm-diodes ) if you can't swing $34/diode - these diodes are intended for continuous operation (in projectors and other such high-duty-cycle applications) and so will likely last much longer, especially if not run at full power.

The Oclaro is also $25/piece in quantities of 5 from DTR, and he may have a further price break at 10 units if you PM him (depending on if you actually need that many)

Your logic in picking a 400mW diode to run at half-power for longer lifetimes was totally sound - you just didn't actually choose a 400mW diode :P
Click to expand...

Well that's just lovely

I cant really use a higher power diode though with the drivers I have I didn't think?

I have the adjustable x-drivers and I thought they were specifically for the red diodes.
 
irishluck said:
Well that's just lovely

I cant really use a higher power diode though with the drivers I have I didn't think?

I have the adjustable x-drivers and I thought they were specifically for the red diodes.
Click to expand...

There are many x-drivers, none are specifically for red diodes, you may or may not be able to use them for a higher power diode depending on the adjustable range.

Alan
 
irishluck said:
Well that's just lovely

I cant really use a higher power diode though with the drivers I have I didn't think?

I have the adjustable x-drivers and I thought they were specifically for the red diodes.
Click to expand...

You can use a higher power diode with the driver exactly as it is, you'll just get less than the full rated power output of the diode (the idea being to run it at a lower current & thus get more lifetime out of it) - the Oclaro diodes are quite happy to run on 200mA.

Depending on the forward voltage of the diode at the current you're pushing, it may or may not make the driver run a bit hotter - ~200mA shouldn't be an issue for any x-drive, however.
 
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