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Thread: what do I need just for powering laser diodes?

  1. #1
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    Default what do I need just for powering laser diodes?

    EDIT: The way some of the members here have desperately tried to identify my location and nationality for whatever reason they believed was needed for by asking an admin to check my profile logs and researching me by the content of my posts has been very creepy and unnecessary. So bye.
    Last edited by dream; 04-28-2016 at 16:28.

  2. #2
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    current limiting and preferably also a clean current limiting that doesn't have a lot of spikes/noise as this can kill your diode.
    Diodes grab as much voltage as they need and not more but will grab as much current as they can possibly can get a hold off till they burn out.

  3. #3
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    I would reccomend a lab style powersupply. With it you are able to set both voltage and current. You probably will fine it suite usefull in many situations later. Dont buy the cheapest økes om ebay, as they probably agent delivering clean poser for LD use. (My psu have had a few diodes pop for no obvious reason bit dirty current. Saging a few USD have become expensive).

    Using tablet to write is a bitch.
    Last edited by Datsurb; 03-14-2015 at 10:19. Reason: typo
    __________________________________________________ __________

    More projects than time available.
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    Just got to love lasers!

  4. #4
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    I would also suggest a lab style power supply.

    Just make sure to never make or break connection while power is on.

    Good practice:
    -Ramp current up after power up
    -Ramp current down prior to power down.
    -Never just yank out/on the main power switch.

  5. #5
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    ... I'm using a pretty old lab dual-powersupply with regulators for 0-30V and 0-1A - for testing diodes I'm setting the voltage at around 5V and the current to 10 mA, then connect the diode and rise the current until the needed value -- I can even remove or set the connections without popping the LD's ;-)

    I'm using it regularly for testing/measuring the diodes or adjusting the focus distances of 200mW@405nm, 2W@445nm and 9W@975nm diodes ... the high power types with max. 2A (both outputs in parallel), otherwise I'm firing them with my own drivers with up to 20Amps max. current ...

    Viktor

  6. #6
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    The problem with lab or bench top power supplies is that voltage spikes during switching or connecting are not a specified feature. Hopefully, and more probably in the better quality ones these excursions will be small and not damage the laser. But, why chance it. Setting up a driver with a dual channel power supply works well and you can set up the driver with a two pairs of input connectors so that one channel provides the power and the other controls the modulation.

  7. #7
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    I use an LM338 IC in voltage reg mode (pot controlled) connected in series to an LM 338 configured in constant current mode to test all my LDs. Good for 5A w/ a good 12V xfmr, bridge, and 15000uF cap. Just change the resistor to control the required max current for the LD that you're testing. (The chips do have to be heatsinked.) I can link to the website schematics if U want.

  8. #8
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    I'd like to know
    And thanks planters, and everyone.
    I should improve my knowledge on electronics before thinking of building a driver myself.

    From all the info it seems I should get few specialized laser diode drivers without the analog modulation stuff to spare some cash for now.
    Last edited by blue; 03-15-2015 at 06:01.

  9. #9
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    ... look here for some laser related infos - http://www.reprap.org/wiki/Laser_Cutter

    After "4. power-source" is the basic schematic of a pretty simple constant high current driver with LM317 and summed/averaged 1A per chip - when changing the LM317 with LM338 and the 0.22 Ohm resistors with 0.1 Ohm, the chips will give 2Amps each ... I don't drive LM317 higher than 1.2A and the LM338 not higher than 2.5A over longer times, or they'll generate much heat.

    Look into the datasheets of the LM317/LM338 for other configurations and adjusting for specific voltages or currents ...

    Viktor

  10. #10
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    Carefull with the lab style power supplies.. they will do the job but some of the cheap chinese ones have been known to generate a spike upon shutdown with something connected I believe.
    Unless you are using a known brand please check things with an oscilloscope first

    LM317 option is cheap but keep a margin in the current you give it.. that way if there are spikes they change they largely exceed the rated current is much lower.. this is actually why cranking up diodes in current is risky on top of more wear and heat output

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