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Running Multiple Lser Diodes. (NUBM08)

AngelG

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There are Chinese DC CC CV switching mode buck regulators on ebay. I'd use one of these for higher efficiency and less heat. For 4 diodes x 4.5v you'll need to tune it for at least 18v and the current limiting should also be tuned and verified before you connect it to the diodes. You'll need at least 20v battery to supply it unless you decide to provide each diode with it's own. And the battery must have high current capability. Also i'd replace all electrolytic caps with better brand ideally, Japanese Rubycon.
 
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Bowler

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Hi red,

I've changed it now, that missed my eye!

Can you check my latest post I replied to you with. I've put in a wiring drawing, and some questions that i hope you can answer.

Cheers
 

DashApple

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Nothing will work if the capacitors are in series with the regulators "in" on that schematic
 
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Bowler

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Hi Red,
Thanks for the info again.

I plan this to be a permanent job, so with the correct and most efficient way and yes, also the safest.

So my main question is. what would you propose I do and the components I use, battery etc and any more suggestions.

The company I work for is quite resourceful, so I will be able to take sheet steel from there and made their own heat sinks.
My plans are to form my circuit onto an electrical bread board, so it will be a easy clean job. and probably encase this with a cooling fan.

For the laser diode array, I have a fully copper heat sink which also has a construction for a cooling fan.

Before I do all of this tho, I will be making a wiring schematic on a wiring software just to make sure it works etc before i go through with the plan.

Cheers.
 

RedCowboy

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Your capacitors in your drawing won't work.

Sheet steel is not useful for moving heat,....... ok I see you said copper and a fan, that's good.

How long will this block run, what is it's purpose.

Is it meant to be portable, linear regulators are not nearly as efficient as switching/bucking drivers, they are just inexpensive.

If you are trying to power it for portable use on the cheap then use LM 338T's and mount with isolators to aluminum, if you are using a 7.5v 250a battery as you mentioned then get either 8 x LM 338T's or bucking drivers.

What is the purpose of this, will it be portable? You will need to move a lot of waste heat, also the beam quality of the 08's typical GBall is not very good, are you making a blue spotlight?

Some info would be helpful.
 
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Bowler

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Iknow the capacitors won't work, ignore them in that schematic it was just a spare of the moment.

And okay, I will ba able to get sheet aluminium too.

Block will run for max 1 minute at a time.

It's going to be used for cutting up/ engraving on glass reinforced polyester. And very very thin metal Iknow I will need optics,

Would be stationary.

Thanks
 

diachi

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Iknow the capacitors won't work, ignore them in that schematic it was just a spare of the moment.

And okay, I will ba able to get sheet aluminium too.

Block will run for max 1 minute at a time.

It's going to be used for cutting up/ engraving on glass reinforced polyester. And very very thin metal Iknow I will need optics,

Would be stationary.

Thanks
IMO, if that's what you're trying to do, you're going about it the wrong way.

Even with PBS/Knife Edging you're going to have a big beam, even focused. Without those it'll be even worse...

More details about what you're trying to achieve and planned optics setup will help us help you, if you want that is.
 
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diachi

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Just buy a 40W C02 USB ready laser, this is meant as a light source to pump phosphor.

Have you already bought the block?

40W USB CO2 Laser Engraving Cutting Machine Engraver Cutter New Control Board | eBay
This^^

I was thinking along the same lines - even just a CO2 tube and PSU without the engraver part - and thne build that part yourself to suit your requirements. Or get a fiber coupled IR diode array or something, at least those options give reasonable beam specs for cutting/engraving.

An 08 block is far from ideal for the job.
 

Bowler

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Hi Red and Diachi,

My idea is that It s going to be used as an in expensive cutting tool, much like styro did, its mainly going to be used for the above and cutting up other general bits. I will have a the optics ready and yes I already have the bank. I think if you get the bean to a good concentration then it will easily cut through things.

Cheers
 

diachi

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Hi Red and Diachi,

My idea is that It s going to be used as an in expensive cutting tool, much like styro did, its mainly going to be used for the above and cutting up other general bits. I will have a the optics ready and yes I already have the bank. I think if you get the bean to a good concentration then it will easily cut through things.

Cheers
Inexpensive cutting tool? Really? :confused: :confused:

Table Saw

Cheaper, faster, no laser safety hazard and will simply work better all round.

Your idea isn't going to easily cut through things and will also likely scorch things without gas assist.
 
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RedCowboy

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If you use a big lens all you will have is a crude fire starter, a cutter/etcher NO WAY, not without an obscene amount of corrective lensing.

If you use a big lens you will be converging already unevenly diverging beams. It will not be precise at all.
 
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Cyparagon

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...I understand this stuff... However we did not study LD in my course...
Which is precisely why you should build something smaller FIRST. What do you have to lose by doing so? Alternatively, what do you have to GAIN by doing so?

There are Chinese DC CC CV switching mode buck regulators on ebay. I'd use one of these for higher efficiency and less heat.
1) you clearly haven't ever seen those on an oscilloscope.

2) They're probably hard to find in the 40-50V range.

3) Linear regulators are actually quite efficient at higher voltages. 4V drop on a 40V load for example is 91%, which is more than most switchmode regulators.

if you are using a 7.5v 250a battery...
That won't work for series operation. Parallel is the worst way to run this.

My idea is that It s going to be used as an in expensive cutting tool




Okay, so this thread was a (almost) total waste of time. This is exactly why I ask people what they're using the laser for EARLY in the thread. I forgot this time, or I just assumed you were going to dick around with it (it's what I would do). I'll leave the above comments in, in case someone else finds them useful.

If your goal is to cut things, a cucumber would be only a slightly worse tool to use. Please re-evaluate your priorities.
 

RedCowboy

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91% is not bad, and on the cheap too, if the battery pack was hand made from 3.7v cells you would no doubt come out better there as well.

12 x 3.7v 26650's in series vs. 8 strings of 2 means you get it done with 12 cells rather than 16 and just 1 regulator set at 3.5 - 4.5 amps. I did see 36v as the maximum differential, but I read the 138/338 could handle several 100's of volts and 5A continuous with 7A surge, so it looks like a dozen 26650's in series and a single 138/338 mounted with an isolator to the heat sink would do the trick running the 8 laser diodes in series of course.
 
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