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Blackbuck 8M Driver Heat Sink Advice

rmarino

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I purchased a blackbuck 8m driver for a NUBM44-81 diode (7W).

I will probably not run to the upper power limit, but the intended application is a homebrew laser engraver, so it will likely be on for long enough that a heat sink on the driver would be prudent. I have space and cooling air available.

I have seen one recommendation for a 14mm heat sink on the "bottom" of the driver, but this doesn't make much sense to me - it seems like it should be attached directly to the regulator chip. The thing I like about the bottom is that it will be easier to keep it in front of the cooling fan while still potentially keeping reasonable access to the current limit adjustment pot, but don't want to cook it while cooling the wrong part of the device.

Anyway, any advice or success story regarding a robust cooling solution would be much appreciated.
 

paul1598419

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Most of these drivers have particularly dense traces and are heat sinked to copper mostly, from the bottom. That is the most efficient way to heat sink a driver now. But, you must also be aware of any through hole contacts that can short out against the host. Most people use thermal tape to cover the bottom of the board and either use a thermal adhesive or the adhesive from the thermal tape to make to good thermal connection to the module's back or a pill or some other part of the host.
 

rmarino

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Both of these responses were super helpful!!!
Thanks much, I feel a lot better about sinking from the bottom and will heed the warnings about shorting.
I like the copper sinks, I will probably use them instead of aluminum.

I appreciate the quick replies!
 

rmarino

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Okay, I guess I didn't think too much about the Pi sinks only being 5mm tall - they look bigger in the picture :)
I'll probably just start with a nice big aluminum sink on the back and watch the temperature.
I should be able to mill the sink to avoid the through hole connections and properly insulate electrically.

Again, thanks for the quick and helpful reply!
 

RedCowboy

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You don't need the thermistor, if you are not using an additional pot you must use a switch or a jumper between the 5V reference and ground, and along the way I think they changed the 3 tabs as for what's what, so depending on which edition you have it's different, it's the bottom two but used to be the first two like in this pic of one I bought early on.



 

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Mosc007

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The Blackbuck 8M runs very hot even at 4.5 Amps. I can't imagine it could ever run for more than a few seconds at 8 Amps.


This is how I did the heatsinking on my Nubm44 Lab Style build. There are 2 Heat pipes from the 2 IC's to the main sink. The Copper sink was thermally bonded to the diecast case it was all put in. It should run forever at 4.5 Amps.

I did put a Pot on the modulation input so I could adjust the output.
 

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RedCowboy

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I just bought some astral 5A built much like the SXD, have you used those yet ?

You can use a little square of aluminum or copper between the driver and your heat sink with compound on both sides to keep the connections from shorting on the BB8, ---edit--- Yes you must have made it very thin and pushed through.

I really like the SXD but availability is an issue ATM.

https://www.ebay.com/itm/Astral-Sup...757274?hash=item4b4a756eda:g:yZkAAOSwqxZbXV16
 
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paul1598419

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I have the same BB drivers you do, Chris. I hope I don't have problems with mine when I use them. The astralist driver gets very hot too at 4.5 amps. One reason I bought the BBs was to mitigate the heat issue with the astralist driver. I am getting concerned about using these drivers at 4 to 5 amps now. :undecided:
 

RedCowboy

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Well darn, I was thinking I could use the arctic alumina to mount it at the 8 pin chip like I have been doing with the SXD's, I really like the SXD but their availability may be an issue ATM.
 




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