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Blue laser 74W NUBM35 Portabl?

Borislav@87

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Hello. I am considering making a portable 75W laser. I am not very familiar with what I would need for this. The laser diodes that will be used are NUBM35 74W. The driver that will power them will be the one in the picture because I was told that it is suitable for this power. I will use 8 18650 batteries. I think they will do. They will be placed in two boxes of 4 each. I haven't come up with a body to put it all in yet, but I have ideas. For cooling, I will put a large aluminum radiator without active cooling. What else will I need?
 

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Joined
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The problem with these arrays is the aggressive divergence of each chips fast axis and the imperfect alignment, but they can be fun to experiment with, make certain to employ all safety measures, always wear your laser safety glasses.

SANY6352.JPG

SANY6315.JPG

SANY6286.JPG
 

Borislav@87

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@RedCowboy
I'm still hesitant to take the plunge because I might not be able to pull it off. I had settled on this variant of laser diodes with this driver. In this case, I will only need a power supply and a suitable body to mount all the components

 

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kecked

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By power supply I hope you mean constant current driver
 

Borislav@87

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By power supply I hope you mean constant current driver
Yeah, I'm wondering which driver to use because the one I listed has had complaints about it destroying a few diode arrays.
 

Borislav@87

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I was told this one is ok, but it's not available at the moment

 
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I just use am LM338 configured as a current limiter.
Note: Don't be concerned about the spec sheet saying 35V limit, that's when configured as a voltage regulator, but when configured as a current regulator I have ran them in excess of 100V no problem.

 
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Borislav@87

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I just use am LM338 configured as a current limiter.
Note: Don't be concerned about the spec sheet saying 35V limit, that's when configured as a voltage regulator, but when configured as a current regulator I have ran them in excess of 100V no problem.

I am not very familiar with how this current limiter is connected. And what else needs to be added to it if power is used from 8x 18650 batteries connected in series. I need some kind of diagram to get an idea
 
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Do NOT configure as a voltage regulator, configure it as a CURRENT regulator, I set mine at 3.5A and later push it to 4.5A but really 3.5A is enough and you have less waste heat. Three 1 ohm resistors in parallel will give you about .33 ohms which is good for 3.5-3.6A


LM317-Current-Regulator.png


if you used a 10 ohm resistor you would get 0.125A
if you used a 1 ohm resistor you would get 1.25A
if you used a 0.10 ohm resistor you would get 12.5A however the LM338 is rated to 5A
if you use 3 x 1 ohm resistors in parallel you will get 0.333 ohms which means you will get 3.78A
if you use 4 x 1 ohm resistors in parallel you will get 0.25 ohms which means you will get 5A

Also you split the heat load so you can use 3W rated resistors when you use 3 x 1 ohm resistors in parallel.

You can use 9 x 18650 cells in series and use an LM338 for each string of 7 laser diodes, the NUBM35 has 2 rows of 7 each so I power each string with an LM338 that way I can turn on 1 string of 7 or the other or both.

SANY6643.JPG

This is a unique NUBM35 that uses two rows of four ( wish I could find more ) so I run all 8 in series using an LM338 and 10 x 18650 cells in series.
It makes a nice little 8 beam cluster, here it is without any extra optics running raw, I enclose mine in boxes to reduce flare from the factory gang lens which can be considerable. Note without any fan cooling the duty cycle with this much sink is about 60 seconds, it's better to mount your NUBM35 to a finned heat sink and use a small fan. This is an early tester which is why it's so dusty, still works as you can see.

SANY6647.JPG
SANY6649.JPG
SANY6652.JPG
 
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Most LM317 are only good for 1.5A, you need a LM338 good for up to 5A, they are dirt cheap, I have done well with the LM338K
 

Borislav@87

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So I will need
9х18650 batteries connected in series,
1 х LM338,
3 х 1ohm resistors.
All this will suffice for NUBM35
 
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You need 2 x LM338 and 6 x 1ohm 3W resistors so you can power each string with one and turn on/off either string, but you can also use 17 x 18650 in series and just 1 x LM338 running all 14 diodes in series, I have done it both ways. You can get away with 16 x 18650 fully charged running at 3.5A if they are good quality cells.

NOTE: You don't want to use too many cells or you will have more waste for the linear to turn into heat.
 

Borislav@87

Active member
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Messages
232
Points
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You need 2 x LM338 and 6 x 1ohm 3W resistors so you can power each string with one and turn on/off either string, but you can also use 17 x 18650 in series and just 1 x LM338 running all 14 diodes in series, I have done it both ways. You can get away with 16 x 18650 fully charged running at 3.5A if they are good quality cells.

NOTE: You don't want to use too many cells or you will have more waste for the linear to turn into heat.
Yes, I understand now. I will connect the two rows of diodes separately. Each to their own as you say. I'll draw a diagram later and when you can look at it if it's ok. I will be using a large heatsink without a fan because this invention will be used in short intervals. I can't overheat it because I'm familiar with it. However, making the two drivers will be quite difficult because they are large and must be fixed on a metal plate. My goal is to make the laser portable, like everything packed into a screwdriver body. I also have a damaged massager that also does the job.
 




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