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Thread: Heat Sinking Requirements

  1. #11
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    Default Heat Sinking to the Base Plate

    That sounds good. I guess that would be a plus for having a metal base plate... I don't ...

    So the most simple way to sink these properly would be to put the module in a hunk of metal attached to the base plate?

    Then if you don't have a base plate I would then need to put the module in a hunk of metal with fins on the top with a fan maybe?

    I will see what I can come up with.

    I see Dr. Lava Just had a larger than axis module attached to an angle bracket attached to an plate. He was running his at 400 mW output. Another neat setup I have seen was the knife edged kit (very impressive BTW). It was 2 axis modules in a hunk of metal attached to a plate. Are these setups sufficient without attaching their plates to a metal projector plate?

  2. #12
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    Somebody find me a Nichia data sheet with a spec saying Tc = N degrees C per watt for that diode case. If you have the data for a 500 mW diode, its easy to scale.. I'll take it from there.

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  3. #13
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    Default Nichia Data Sheet

    A little bit of googling turned up one for a 50 mW diode:

    http://www.datasheetarchive.com/pdf/...DSA0012451.pdf

  4. #14
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    if kvant and rgb tec their 445 modules ill be tecing mine
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  5. #15
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    Lightbulb

    Quote Originally Posted by andy_con View Post
    if kvant and rgb tec their 445 modules ill be tecing mine
    Ther is a TEC underneth the diode holder for both the reds and the blue in my 1W Spectrum.

  6. #16
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    Quote Originally Posted by cfavreau View Post
    That sounds good. I guess that would be a plus for having a metal base plate... I don't ...

    So the most simple way to sink these properly would be to put the module in a hunk of metal attached to the base plate?

    Then if you don't have a base plate I would then need to put the module in a hunk of metal with fins on the top with a fan maybe?

    I will see what I can come up with.

    I see Dr. Lava Just had a larger than axis module attached to an angle bracket attached to an plate. He was running his at 400 mW output. Another neat setup I have seen was the knife edged kit (very impressive BTW). It was 2 axis modules in a hunk of metal attached to a plate. Are these setups sufficient without attaching their plates to a metal projector plate?
    You could build your diode holders into a CPU heatsink and fan combo.

    I've done the TEC route, but as you don't have a metal baseplate....
    http://img62.imageshack.us/img62/3985/laser.gif

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  7. #17
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    Default

    A nice big baseplate with other lasers on it etc makes a great heatsink. If your baseplate is going over 50C, then I'd be worried about more than just your 445nm diode!

    There is really no need to TEC cool these diodes, unless you intend on pushing to the absolute max. TEC'ing them just means more heat to dissipate in your baseplate, or whatever you use to cool the TEC.

  8. #18
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    Default Data Sheet Facts

    I have been doing some reading and some experimentation.

    The Nichia data sheet (link posted above somewhere) states that the maximum operating temperature is 60 C (140 F). It also states an interesting fact that there are parameters that change with temperature. Besides the forward current / voltage being affected by temperature the peak wavelength is too. Run it warmer and it gets more blue. Run it cooler and it gets more purple. Of course this is exagerating things quite a bit. The swing in wavelength is only 3 nanometers... I don't think you could see that so it doesn't matter. Getting to the point... the threshold current is affected by the temperature. I stated earlier that I was experiencing a very noticeable dimming at 40 C or a little above. I was running the diode at 210 mA. This apparently is close to the threshold (so the forum says). Close enough that when the diode reaches 40 C it is even closer. The 50 mW diode in the data sheet has a swing of 10 mA threshold current from 20 C to 60 C. Who knows what the Casio diode is for sure... Interesting to note for us though. Anyways getting back to the experiment. I bumped the current up to 333 mA and it runs fine for over an hour topping out at 50 C (122 F). The data sheet does state that Nichia recommends operating the diode strictly below the maximum ratings because of the diodes "high current density" (i.e. .3 A to > 1 A going through a little tiny chip. Definitely a good idea to do so. It does not however say anything about reducing life expectancy at 50C or life expectancy at all...

    In conclusion running the diode at less than maximum ratings appears to have no short term detrimental effect (I do not have a power meter so this is a subjective thing). A Axiz module all by itself should be sufficient for running the diode at lower powers, however some additional passive heat sink is recommended. It is handy to have a thermocouple as I did to measure temperature because the diode will probably self destruct past 60 C.

    Does anyone have any pictures of there diodes mounted and heat sinked?

  9. #19
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    Default DataSheet for the 1W+ diode in Casio Projectors

    Here it is...

    http://www.promodisc.com.br/NDB7352-E.pdf

    Max casing temperature stated: 30° C

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