NUBM44 6W+ 450nm Laser Diode

[RedCowboy]

Rick, where do you see fold back?
Granted no one want's to drive on the edge of foldback for many reasons, driver variances, degradation over time, excessive waste heat, shortened lifespan.

But where do they actually fold back and how consistent is that point, what is the range for actual foldback?


Again I know we want to stay at least 1/2 an amp south of median foldback, but in your testing where is that....5.25 amps ?

What is the worst you have seen? Forget the best, but out of any batch what is the lowest foldback you have seen?

Thanks.

p.s. I know the simple answer is stay 4.5 amps and under, but I still am curious as you have tested so many.

 

[ricktrent4]

Rick, where do you see fold back?
Granted no one want's to drive on the edge of foldback for many reasons, driver variances, degradation over time, excessive waste heat, shortened lifespan.

But where do they actually fold back and how consistent is that point, what is the range for actual foldback?


Again I know we want to stay at least 1/2 an amp south of median foldback, but in your testing where is that....5.25 amps ?

What is the worst you have seen? Forget the best, but out of any batch what is the lowest foldback you have seen?

Thanks.

p.s. I know the simple answer is stay 4.5 amps and under, but I still am curious as you have tested so many.

It has been a about 4 mo. I think it was around 5.2A to 5.4A .
I will try to retest next week email me around Wed as a reminder I have a lot going on.oke:

 

[Alien Laser]

I have it at 5A / 7.3W

 

[RedCowboy]

Is that with a G2?
I wonder what one of podo's 3X expanders would do for it?
I may try one after a 3 element.
I really need to build one with my cylindrical lens, I wonder if G2 + cylindrical pair would work with that 3X expander, I keep finding that one lens effects the next.

 

[Alien Laser]

Am using the G2 / sometimes i get to 7.5 when batteries are charged then it drops down to 7.3 and then very slowly it starts drooping down very slow 5A is eating the batteries am using 2x16340,AW's when i use the extender then i can use 2x18650 Battery's i only have one AW in this size so i have to mix it whit other 18650 battery's i have so i don't use it.
am getting one more NUBM44 on the 19th

 

[Roger O]

Hi everyone, I'm thinking about getting one of these diodes and driver from Jordan. I realize that the max power is high, my question is does anyone know how to simply adjust the power down and back up as needed for experimentation?

Reducing the input voltage with a potentiometer is an easy fix, but I don't know if the driver can handle that on along term basis, and don't want to risk destroying an expensive diode and driver.

Thanks for your input!

 

[Cyparagon]

Hi everyone, I'm thinking about getting one of these diodes and driver from Jordan. I realize that the max power is high, my question is does anyone know how to simply adjust the power down and back up as needed for experimentation?

You really want a bench power supply for that. Even if you get a driver with an adjustment pot, the contact noise of moving the wiper may be enough to kill things in certain cases. Bench power supplies either have encoder wheels, or higher quality pots with filtration.

 

[Roger O]

Thanks for the reply. I am using a lab power supply, and the laser I currently have is a lab module.

The problem is that the difference between the minimum voltage and the maximum is very small (less than 1 volt), and does not give me an easy way of adjustment. Perhaps a better power supply, or a different approach?

 

[Cyparagon]

You would drive the laser diode directly from the power supply. No intermediate driver. Which lab power supply are you using?

 

[Roger O]

One of the Chinese regulated supplies. I am concerned that it I drive the diode directly from the power supply, the current regulation will not be good enough.

I would have thought that some of the experimenters on the board would have developed an easy way to modulate the laser power output of any diode from off to full and any where in between.

 

[Light superglue]

Hi Roger O,

I have NUBM44 with drivers from Jordan and I am combining them with PBS.
In order to do beams adjustment at lowest light intensity I use the cheap RGB dimmer from aliexpress to decrease the voltage supply of LiPo battery to the drivers and it works great without using any big lab power supply. I can regulate independently 2 drivers with 2 knobs. Maybe can use the 3rd knob for 3rd driver, but never tried, because this dimmer has total 9A limit.

For example, I have mesured that at 9V to the Jordan's SXD driver the laser power is maximal 7+W, but at 6V to the driver it is only 2,4W, and so on to the very weak beam (however the wasted heat can still be about 10W even if LD is emitting milliwatts).
This is the picture:

 

[RedCowboy]

6.8V is the cutoff for the SXD to regulate, that's if your batteries can provide the current needed without sagging below 6.8V the SXD will maintain the set output current.

I find the NCR18650B struggles after 60 seconds when using 2 in series, 3 may help but I use INR or IMR cells and that reduces sag.

I know you are restricting the input but I don't know that that's a good long term solution, the designer lazeerer could tell you more.

p.s. In your pic your SXD is not heat sinked, at full power it will get very hot very fast, it's bet to use some HS compound and sink the 8 pin chip. :beer:

 

[Light superglue]

My full power experiments never last more than half a minute, and I let 5-10 min rest between them to let all parts to come to room temperature.

The driver at 5A in shaft holder is glued to Al body by Jordan, so must be heatsinked. The one set 4.5A is not, but this is not the most expensive part of build and may be replaced if fails.

I am not specialist in driver design, but this RGB dimmer from dx.com works extremely well - I can adjust beams and optics without burning fingers. By cutoff voltage you probaly mean the lowest input voltage when it can output the preset 5A maximal current. But at lower input voltages the system does not turn off, simply outputs less current and LD dims. This dimmed millivolt output is very stable, even if I did not try it for more than couple of minutes. The drivers do not heat too much, and am not sure how would it be possible to damage them by restricting input voltage.

2 months ago I have mesured efficiency of the combination "NUBM44+5A preset SXD driver from DTR" by mesuring input voltage/current and laser power:
6V - 2.4W
7V - 5.3W (current 2.75A) what means efficency of 27%
8V - 6.9W (3.7A) - 23%
9V - 7W (3.14A) - 25%
10V - 7+W (2.72A) - 26%
11V - 7+W (2.47A) - 26%

I used 12V lead battery at that time, then I switched to 3 cell LiPo, so this table may change a little now. 18650 from dealextreme started to cry over 3A, so I prefer not to use them for these LDs any more.

 

[RedCowboy]

Sure I quick test with a single 3.7V cell, but Angelos could tell you more about it, I have heard that we should not try to regulate by input but that's just what I have heard, it's an op amp design.
Pinch that driver between your fingers and give it full power for 10 seconds, then post a pic of your blistered fingers LOL, they really need some kind of heat sink. Just try holding it and see.
Also it's not killing it that I worry about, it's overheating it and losing the spring tension in that little graphite based pot, then output could drop with heat or so it seems, I'm not trying to be an azz, I'm just telling you what I have heard.

 

[Light superglue]

You are right, I did not realise that driver gets hot so fast. Thank you.

However I did not have problems before with any of SXD drivers on these LDs.

If this laser can ignite paper in 2 seconds, why to keep it on longer?

 

[RedCowboy]

If you want to light cardboard at 20 feet you need to bear down longer, no laser is without some divergence, and it will either be getting tighter or looser over distance, so as the spot covers a little more area, more time is needed to reach flashpoint or add an adjustable beam expander.