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Thread: Bizarre simpledrive II driver problem

  1. #51
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    Nov 2010
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    Something incredible happens to your lasers. As dkumpula told you, this 2500mA driver is not optimal for 100mA diode (its range of operating current is just above the error of the current setting for v2500), especially since you for some reason do not want to use LASORB. The v2500 does not have a quality control system for the supply voltage, but it has a 330uF filter capacitor, which is sufficient in most cases. Really, I do not know what's going on with your setup, maybe your driver was corrupted by the previous owner and needs to be calibrated maybe something else

    For good cable management and EMC there are no barriers
    are we talking about the power supply wires or the wires that feed the laser diode being a twisted pair

  2. #52
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    no, I am going to using a lasorb , I did not have a spare for the other one and was using a switching diode till I could get my hands on another lasorb for that wavelength, I have one now for the 490 blue, my boss gave me one, and I am going to mod the driver I have with your instructions, when the original 490 failed it was just running and died, I was not doing anything with it but shining it into optical calcite. I can post pics of that if you want

    I was just confused by not getting any feedback from you, and wondering when I will get the 490nm diode.

    I fully intend to mod the driver and I now have a suitable lasorb, just waiting on a diode.

    The 520nm laser diode has always had a lasorb on it and it's working just fine,

    and to clarify a bit more, I was comparing the startup noise with a lasorb compared to a high speed switching diode and posted the pictures of the waveforms, I knew there was a risk to the 505nm diode with this test comparison and I know why it failed. I think I mentioned that the 505 had a lot of hours on it as well.
    Last edited by Draco; 06-10-2018 at 22:55.
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  3. #53
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    I have not followed the whole thread but is there any possibility of a back reflection blowing the diode? Calcite does strange things to light. Some diodes are very sensitive.

  4. #54
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    Yeah, kecked makes a good point. My builds frequently have the diodes pointed directly at the face of a PBS cube and I believe I have seen sensitivity for 520nm and 405nm diodes to this arrangement. I have attempted to compensate with by making the angle a bit off from 90 degrees and sourcing cubes with better AR coatings. That said, these diodes are known to be sensitive so lasorbs and other precautionary measures are prudent.

    Also in case there was some confusion, BBE and DTR are not the same person. They live on opposite sides of our ‘little blue dot’.

    David
    "Help, help, I'm being repressed!"

  5. #55
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    I never thought of the back reflection, and thank you for clearing up the confusion it was DTR that said he was replacing the diode and he is not responding to stuff I send to him, I was confused thinking BBE was DTR, sorry for that,

    The back reflection I know can damage video projectors as well, I found it fascinating that the calcite fluoresces in the beam path but otherwise does not do that with UVA or UVC
    Attachment 54196
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  6. #56
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    The long open-can reds (single-mode 660 nm diodes) from back in the day were *notorious* for blowing up due to back-reflection. They had a max output of around 300 mw, but at that level the intra-cavity flux was something like 10X higher (so ~ 3 watts). Given how small the emitter was on those things, it's no wonder they were so sensitive. They were already operating right at the threshold of catastrophic damage to the emitter face. So yeah, a single stray beam going back to the diode was all it took. Instant LED. It didn't even have to be a perfect reflection. Catch a stray bounce from an optic, or even from a polished metal mount, and you were suddenly cursing up a storm. I once killed one from the reflection off the blade of a flathead screwdriver! (D'oh!)

    Lasorbs were great for preventing static from killing those diodes, and they worked really well to help smooth out the spikes we'd see from some of the shitty drivers we used to use back then, but they couldn't save the diodes from back-reflection. In the end everyone learned to align everything at 10% power and only crank it up once you were certain that everything was perfect and the case was sealed.

    A little side note about Lasorbs: they must be installed as close to the diode as possible. For sure no more than about an inch away. If the total length of the current path from one end of the lasorb, through the diode, to the other end of the lasorb is more than about 5 cm, the diode can still be killed by static even if the Lasorb is functioning perfectly.

    Bill Benner did some tests back when Pangolin was developing the Lasorb, and he discovered that he could kill a diode with a single static discharge (~ 20KV from an ESD gun) even with a strip of braided copper ribbon directly shorting the two leads of the diode, but only if the braided copper ribbon was more than 5 cm long.

    Adam

  7. #57
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    Quote Originally Posted by buffo View Post
    The long open-can reds (single-mode 660 nm diodes) from back in the day were *notorious* for blowing up due to back-reflection.
    I still use LPC-840 open can 650nm diodes combined with 638nm reds to give a bit more range on the high end of the spectrum. I haven't damaged one of those, but I'll keep this in mind.

    A little side note about Lasorbs: they must be installed as close to the diode as possible. For sure no more than about an inch away. If the total length of the current path from one end of the lasorb, through the diode, to the other end of the lasorb is more than about 5 cm, the diode can still be killed by static even if the Lasorb is functioning perfectly.
    I believe that Bill has said to keep attach Lasorbs no more than 1cm from the diode. I've started attaching mine directly to the diode pins. This is a pain in the butt!

    -David
    "Help, help, I'm being repressed!"

  8. #58
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    I have been putting them on the diode leads as well
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  9. #59
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    Did you not see my reply to your last message which had the shipping details I sent to your sbcglobal email? Other than that don't see any more recent messages. Anyway you said you were out of funds but really needed the diode and asked if I could send you one to replace the one that got damaged. Since you had a number of past purchases I said I would help you out and send you a free one. It shows delivered this morning so you should have it and can get back up and running.
    https://tools.usps.com/go/TrackConfi...99939024476096

  10. #60
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    I use the brass mounts from dave and glue them to the top. I then bend the leads down to meet the laser diodes leads and then solder the leads for the driver in the center where they meet. I don't but good idea to add electrical tape to make sure the wires don't touch the brass. I like this arrangement as it also stabilizes the leads from the diode. If you pick off the leads at the top by the lasorb you get some stress relief too.

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