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Thread: 5.6 CAN Diode pinout

  1. #11
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    Mar 2006
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    Quote Originally Posted by marconi View Post
    "Dont use the diode test"
    Thank you... I forgot that one important fact
    Doesn't matter, you had the one that matters. As far as I know, the lower the current, the lower the forward voltage of any diode. This could account for a gentle threshold push revealing the polarity safely, same reason a couple of NiMH's can apparently be used on a diode with no resistor! (See Kaz's post about this here). As I said in the reply there, the nominal forward voltage of 2.7V is never reached, so this singular instance is self-limiting. So I guess the question is: is the first hint of light produced at a forward voltage less than the highest safe reverse voltage? If it is, then carefully and slowly raising the voltage (current limited to 50 mA) and periodically switching the LD polarity between incremental raises will safely reveal the polarity of the LD. If it is not, all bets are off unless you like 50/50 odds of destruction.

    I just tested a couple of fried Rohm diodes with the diode test, (FRIED, so no worries, the facet is nuked, but electrically they should be viable...), and the forward drops were below 2V at the very low meter test current, so you might get light out of them without exceeding the voltage that would kill them if reversed. I haven't got a load of different diode types so I can't do enough tests to give any idea how widely this can be applied.

    Steveo, that Micronta, test the volts on the probes when set to the resistance range (if you have another voltmeter), you might be lucky, it might be around 1.5V. If so, it might be useful.
    Last edited by The_Doctor; 11-21-2007 at 16:14.

  2. #12
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    It's 1.8V I think.. I'll doublecheck..
    (well I thought I waz logging off

  3. #13
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    Default Happy Thanksgiving :)

    Everybody get enough to eat? I'm stuffed
    Ok, got that diode working, now I gotta collimate it. it's got a pretty bad eliptical output, especially the fast axis, so I guess I need some lenses and/or prizms..Anybody know how to calculate the angles of divergence and convert that to the powers of the optics needed. I tried surfing some and got no-where. Better yet a pre-made self-contained one with all the optics already glued and mounted, hehe--I'm dreaming, right?---

  4. #14
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    Hi Steve-o if you read my thread which the Doc has given you the link to it, it clearly states that(i only put a varible resistor in between to adjust the current the threshold of each diode is slightly different on each one, you are compeatly right you must put a resistance between the battery and the diode ) so i dont understand what Doc is saying when i clearly state that i put a varible resitor between the batteries and the diode

  5. #15
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    Uhh- I got the diode working (I've got a 1 ohm in series -it also allows me to directly read the current; and I'm running just above Ith for testing) I was wondering if anybody has an equation that you plug the f-axis and s-axis numbers into and the result would be the sizes and the magnification powers for the lenses and prizms needed for good collimation/ circularization.
    Last edited by steve-o; 11-22-2007 at 13:44.

  6. #16
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    Hi steve-o an equation is only as good as the info that you are putting into it unless you know what the f-axis and s-axis numbers are there wont be much point, if you want a to collimate the beam the little axim modules are ok as a general purpose unit not the best by a long shot but it will get it up and running, in most cases the smaller the beam after optics the quicker is will start to diverge so it all depends on the focal point on the lense you want to use, this probably hasent helped you very much

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