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NUBM44 Dry Ice Run

Andrew124C41

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So, I got to thinking that running back and forth to the store to pick up dry ice to cool the hot NUBM44 was getting a bit old. Paying high school kids to wave a hand fan at the diode proved not only inefficient but expensive.

While what I am about to propose is also inefficient, I wonder if it would work. One would have one set of batteries for the diode and another for cooling. Perhaps putting the 44 into an aluminum radial finned heatsink with one of these in between the sink and the module.

Otherwise, we are going to have to use mind over matter and just keep thinking cool!

Peltier Cooling
 

Alaskan

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There have been some builds which do just that shown here since I joined, but only a couple. I’ve wanted to do the same, came up with some other ideas using a small bottle of CO2 gas to cool too, but in the end I decided to just use a larger heat sink with deep fins instead. I don’t see the extra work building something like that necessary, unless cooling for a wavelength shift or to double the output power.

I don’t know if the pointer I saw with a small circular TEC with a hole in it used separate batteries or not. I’m trying to remember the member name, he also built a PBS cube combined 405 nm pointer.
 
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Andrew124C41

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I have been looking all over the place for a radial finned heat sink that could be bored out either for a 12 or 20 mm diameter module. The only thing I found so far would involve expensive custom work. Where did you find one?
 

Alaskan

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I would have used a much larger diameter heat sink, I like my pointers big, didn’t look for that, the problem I faced was looking for a suitible round TEC with a hole in the middle, they can be found, been years since I looked, can’t give a link.
 

Andrew124C41

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I am going to do an experiment....probably nuts....but I am going to stick a 44 in an S4...not the S4X....but the S4 and see what kind of duty cycle I might have with something so small and portable. I figure what I will do is press the diode in a 12 mm module...set it up without a driver....but use temp wiring to my voltage/current controlled PSU and measure the temps of the heatsink. Since the host is black I should get fairly accurate measurements. There is not much surface area either in the extended tapered copper module or of the S4 itself....
Do you happen to know the max temp for the NUBM44? I know there must be pretty good cooling in the projectors they are used in.
 

RedCowboy

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In the v1/2 they use an aluminum sink with fan forced air, but they also run at factory spec, they do up the current over the 20K hour lifespan to compensate for wear/dimming but the efficiency is better at lower drive current.

I know at 4.5 - 5.0 amps they will heat up the biggest sink given time, the fan forced air over fins is what makes it work all day.

BTW a lot of newer units use a sealed light engine to keep dust/humidity out and employ the copper heat pipe from aluminum sinks to copper pipe/aluminum radiators with fan forced air. Basically a remote radiator outside of the sealed light engine.

Have you ever seen inside the old laserglow HH units, it's like a big Maglite with the core inside surrounded by a webbing of copper brillo pad and a fan at the back.
 
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Andrew124C41

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Check out this thread:

https://laserpointerforums.com/f65/just-out-curiosity-there-max-temp-rating-nubm44-100110.html

If you do use a TEC you will need a sizable heatsink with some good fins, the heat from the operation of the TEC alone needs a lot of cooling, they produce a lot of additional heat on the hot side just operating.
I just saw the specs. What is interesting is that they mention I think it was 3 amps as the maximum current. We are running them at 4.5 amps. I think keeping the diode under 50 c is probably a better idea.

I am not familiar with the TEC. I just looked it up....is it fan or Peltier? Have you or anyone you know used one on a handheld before?
 

Alaskan

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Yea, with this diode being pushed so hard to produce 6 to 7 watts, I bet without a big heat sink you won't be able to keep the temperature at 50 C. for very long, maybe a minute or two using a small 20 mm heat sink, if that. My NUBM44 uses a hunk of aluminium which probably weighs close to a pound, never tried using a small heat sink with it.
 

Andrew124C41

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Yep, I know its a crazy experiment. The heatsink on my double D mag with 2 32650s probably weight that much....and as I said, I would love to use a finned sink.

Have you ever used the TEK?
 

Alaskan

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I have used a thermal electric cooler under a massive block of aluminium once, had four of them sandwiched below it to cool 800 watts of RGB LED's, along with some blue laser diodes mounted to it, you can see it in my avatar as that big round thing in the back of my truck. It worked well, but those are very inefficient, produce about 50 percent more heat output on the hot side than the heat I was wicking away from the LED'S on top of the cold side.

I had a large host made by Ehgemus a few years ago which uses three of those big 32650 batteries, I haven't used it yet. It would be a great host for the NUBM44, the heat sink is great.

 

Alaskan

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I had a three axiz module diode host made by him too, found out you need individual adjustments to be able to get all of the beams to be perfectly parallel. Close in they are parallel enough, but after a few hundred feet you can see they go out in different directions. I'd love to have a multiple diode host made for me, if we could just get some kind of adjustment for each laser diode assembly in it.
 
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So, I don't know how much money you are looking to spend and how much time you have to build something like this, by why not build a liquid nitrogen generator?

I've seen some DIY versions where they either take in gaseous N2 or ones that filter the N2 from the air and then cool it.

There are some projects I've been wanting to do with liquid nitrogen and I threw the idea of building a generator around with my brother and a friend. I think we are going to try this project over the summer when we all have time.

From what i've seen, it would probably cost around $500-$700 to build, but could be totally worth it to have your own cache of liquid N2.

This is probably a long shot, but figured I'd throw the idea out there :)
 

Andrew124C41

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So, I don't know how much money you are looking to spend and how much time you have to build something like this, by why not build a liquid nitrogen generator?

I've seen some DIY versions where they either take in gaseous N2 or ones that filter the N2 from the air and then cool it.

There are some projects I've been wanting to do with liquid nitrogen and I threw the idea of building a generator around with my brother and a friend. I think we are going to try this project over the summer when we all have time.

From what i've seen, it would probably cost around $500-$700 to build, but could be totally worth it to have your own cache of liquid N2.

This is probably a long shot, but figured I'd throw the idea out there :)
Everyone should have one. Have at it :)

Homemade liquid nitrogen generator Joule Thomson Throttle
 

paul1598419

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Bottom line is there's no free lunch when it come to removing waste heat. It all comes at a huge cost, whether you use forced air circulated through heat fins or use a TEC and remove heat from the back side.
 




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