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A little more info about these. @Phritzler suggests (and I concur) that the diodes are most likely Sharp GH04W10A2GC. These are spec'd for 350mW CW and 1100mW pulsed. So running them at 1.5W CW is pushing them pretty hard. They are individually tested so I know they will work at that power, but one possible issue is that the wavelength shifts up at higher currents. I'll fire up the optical spectrum analyzer and get some measurements at various currents and add that data to the spreadsheet.
Thank you for the continued information, Junktronix. I've got two of them sitting on my bench, but I haven't fired them up. If they will fail over time if pushed >1W, then I'd say sticking with the BDR-209 16x 405nm from DTR probably make more sense for most people's needs. Those peak at 1.2W with a G2 lens and are single mode. I run mine at 750mw without issue.Quote:
Originally Posted by Junktronix
It would still be nice to get that sled figured out though!
-David
Running the Sharp diodes at 1.0A is not pushing them any harder than running a 16X diode at 750mA so I don't think the lifetime will be any worse.
I've tested a few of the modules at 1.5W output and the wavelength shifts up to around 412nm. I suspect the 16X diodes do the same, but I don't have one here to test.
Quote:
Originally Posted by dkumpula
Oh, just to clarify, I’m not running those BDR-209s to .75A, I’m running them around .46A so the output with a G2 lens is 750mw. I would doubt they’d hold out for long at .75A (1.18W output).Quote:
Originally Posted by Junktronix
The shift up the spectrum when being overdriven is interesting. I wish it shifted the other way though!
David
Yea 460mA is a good conservative current on the 209's and for sure still way more than the actual manufacturer rated if we had access to that info. I suggest 600mA as a max. When I did the original testing on them many were trying to get over 1W and lots of posts in first several pages of that thread had 750mA listed. Was not long after that it became evident that was too high as most the original builds died in short order. I did edit my posts with warnings about trying to get over 1W by pushing but so many still sell them as 1W diodes. I do know the 209's are reported to be much higher in wavelength. Either they shift a lot or maybe they are actually rated 410nm or something since all we have to go on is the community testing.Quote:
Originally Posted by dkumpula
I have a formula I came up with and like to use with new diodes I offer that I don't have any long term data on for suggesting running currents. Tends to be pretty accurate when looking back after the diode has been around long enough there is a lot of data and feedback. Take the efficiency curve and go about 25%(single mode) or 20%(multimode) back of the knee for low duty cycle applications and 40% back for long duty cycle applications. The knee on the 209's where efficiency starts dropping off is about 800mA with foldback is around 900mA. that would be 600mA 25% back and 480mA for 40% back. Looking at the graph on these the knee looks to be around 1.2A with foldback @ 1.4A looking at the graph. That would make my guess that 960mA for 20% back and 720mA for 40% back. There are a lot of low duty cycle applicators but take pointers as an example for short duty cycle where long term degradation is not as much of a factor. Most deaths are LED or COD damage from harsh cycling, thermal damage from running too hot, or optical damage from contaminates which the multimode diodes have much higher tolerances for heat and electrical abuse. If you think about most probably will never see more than 100 hours if you use it 20 minutes every day that is over 4 years just to get to 100 hours.
1A is probably fine for the lower . The rated current on a datasheet is not a one size fits all as they are formulated to achieve the MTTF life ratings for end use they are marketing them for. Take the diodes marketed for use in projectors as alternative to LED's they underdrive them considerably to get a 20K-30K MTTF where some more general uses are formulated for a 500-5000 hour life rating.
Good advice, DTR! My experimentation building projectors with your single mode diodes over the years LED me (heehee, I couldn't resist that pun) to the same conclusion. Depending on the single mode diode, I back it off 25-40% from the knee. The reds and blues appear to be reasonably resilient enough to handle the ~25-30% back-off while greens need a good 40% back-off to survive (and I don't even run my lasers that often). I hope others follow your guidance and don't suffer from the consequences of being too power-hungry! ;)Quote:
Originally Posted by DTR
-David