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Active cooling for DIY boards / boxes


gizmomkr

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Steve Gardner wrote:


I seem to be in the minority putting my controllers inside but this works well for me. I don't have to worry about water, heat dissipation, or someone walking off with my controllers.


Funny you mention that Steve, had a neighbor ask me if someone stole my controllers what could they get for them? I told them, they probably wouldn't get a thing out of them as they require a computer and specialized software to make them work. They'd only be valuable to someone like me that knows what they are and how to program them.

So yes, my controllers are outside, but they are also LOCKED with a lock and also secured by bolts to a wall, except for two which are secured to the back of two old converted wooden ammo boxes, but then, they are all tied together with cat5, cable ties and cords cable tied, so if someone were to want to try and steal them, it's going to take them a lot of work to get them or anything else in my display. They could do damage, but they couldn't get off witrh anything without a whole lot of trouble and problems getting it loose!



As for the persons fan idea, if it were me I'd be installing no less than three fans near the triacs, one centered and one each end, this would keep the entire set cool. Especially if he has a lot of them lying around around. Then of course there is the fourth fan for the ventilation (blow the hot air out) and then a fifth for blowing cool air in. Personally, waste of time, it just would have been smarter to spend the $20 for the HD heatsinks that LOR installs. And that's what I did, bought all my CTB16PC's assembled and with the heavy duty triacs installed. And I have tons of those fans around too and had thought about it, but having been in electronics for over 35+ years, I knew the BEST way to go was with the way LOR has it! There are times when saving a buck IS NOT the way to go, and for me, this was definitely one of those times NOT to save a buck!

The time and effort to place fans and smaller heatsinks just wasn't worth the risk of frying triacs and murdering my shows!
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gizmomkr wrote:

I know you dont really need it (especially if you have the "full power" heatsink) but im a cheap bastard, and could not convince myslef to spend 20.00 on a chunk of metal. I also know most like to set controllers out in the elemnts, and a fan with air vents would not be desirable - but mine are safe from water, so its not really an issue for me.

So instead of spending another 80.00 to outfit all my controllers with large heat sinks, I have tons of CPU heat sinks and fans lying around that would be easy to attach to my exsisting "low power" stip of metal.

I dont have a degree in thermo dynamics - but I'm willing to bet a CPU fan and cooling block can dissapate as much if not more heat than the "high power" heat sink alone.

I plan to mount 1 block and fan with some thermal paste for each group of 8 channels. I'll probably incase the whole thing in Plexi or Lexan with holes at each end when done.

Just wondering if anyone else has done similar or had issues with cooling.

I have built heat sinks for LOR controllers before... BUT I did take some things into consideration when I did so. I used the chunk of metal approach with a high dollar finned heat sink extrusion material (but I had it on hand).
After seeing the time I spent doing the machining... I just save up and just buy the punch press and metal break version LOR sells. :D

Your method may work fine... I am not going to say it won't since I have no idea what your loads are, or what your sequences look like.
Ernie kind of touched on this with his reply, in that my concern would be that the end channels may not really see much effect from your add on heat sink.

The issue is that the low power heat sinks are thinner aluminum then the high power heat sink, and as such will not be able to "transfer" or conduct as much heat from the triac junctions (the real purpose) to your add on heat sink. Add the thermal resistance increase caused by the fact that you are bolting 2 separate pieces together (even with grease) and the overall application is not as nearly as efficient as the "chunk of metal" approach is. (even with airflow)

Again this all goes back to your load... if it is low enough that you don't "saturate" or swamp your heat sink set up with more heat then it can transfer then you are fine.

Is the add on going to allow you to cool better than the low power heat sinks alone?
To some extent... yes.

Is it as good as the high power heat sinks? I doubt it very much...
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gizmomkr wrote:

Scott T wrote:
... I will be attaching 1 or 2 old CPU sinks like in the picture, and some fans. i'll post the results with some temapture readings when i get it all done for anyone thats interested.

I think we would all be interested in the results. It's one thing to speculate and another to see the proof.

One other thing you might think about is that by itself the heatsink is too small, do you have something to tell you if the fan fails? They do fail and with a PC, you can have software shut it down if the fan does fail for any reason. You'll need something in place to deal with this.
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  • 4 weeks later...

Just food for thought. If the high powered heat sinks are mounted directly to the side/back of a good “metal” box, then you would be far better off???



Yes / No??



Have a good one..



Mikey

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  • 3 weeks later...

If I were you I would try to figure a way to transfer the hest from the heat sinks in the housing to a heat sink on the outside without compromising the weather tight housing thus creating a natural cooling cycle.

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Active cooling sounds good, but for all the work you guys are talking about it doesn't sound like it worth the $20.00 you're going to save buying the low power heat sinks. Also what about powering the fans? Are you going to have to have an external power supply for those? I know there some power on the 18 pin header but is that rated to run fans?

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I ended up only needing to actively cool 1 board. I am using external power, and with everything at full oad for about 30 minutes, things were warm, but not overheating.

I will try and hit it with a temp gun and post results.

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