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Time for my yearly return to the forum... inquiring about NUBM31T

likevvii

Member
Joined
Mar 2, 2020
Messages
67
Points
18
Thank you for the insight.

The Drok driver does say it has CC/CV capabilities?? Maybe I am reading it wrong, but there is an individual POT each for CC and CV.

Is 100-200mv ripple bad? I would assume it would be an issue for a single diode, but over 20 diodes it seems no problem to me. I was testing from 80V to 85V Constant Voltage, and the Power draw of the NUBM31T was quite linear. This was the same to NUBM44(7W) single diode, it was quite linear. I believe modern 445nm diodes 5W+ are different from the traditional diodes. They almost behave like LEDs in terms of forward voltage curve.

When you say "sensitive" Do you mean slight changes in Vin would have large amperage draw effects? Or maybe life expectancy due to voltage spikes, etc?

If I were to use the Drok converter as the driver, what would the potential issues be compared to a "true laser driver"
Examples;
-Voltage fluctuations causing laser diode to wear out.
-Efficiency of "85%" compared to real drivers at "97%"

The reason why I want to avoid using 4 separate buck drivers is because I want to control output with a single manual POT. I wouldn't know how to control 4 drivers with a single pot without having to make a custom PCB.

I don't need clean PWM/TTL pulsing required for laser etching or other similar purposes. I would just turn it on and adjust the current as needed.
I really want to use the DROK driver since it will save me so much time. I looked for hours and was ready to pay up to 1000USD for a driver and nothing was suitable.
I am open to commission a driver to be design and made, but not many people out there would be willing. If I could customize, I wanted to add thermocouples, etc to have even higher safety.

Is there anything wrong if I were to add a 4/5A fuse inline with a driver to protect incase of anything?
I have (accidentally by killing a live-lasersystems.net driver) tested on the nubm31t with short bursts up to 8A and it did not die.
 



Giannis_TDM

Well-known member
Joined
Apr 27, 2019
Messages
658
Points
93
Thank you for the insight.

The Drok driver does say it has CC/CV capabilities?? Maybe I am reading it wrong, but there is an individual POT each for CC and CV.

Is 100-200mv ripple bad? I would assume it would be an issue for a single diode, but over 20 diodes it seems no problem to me. I was testing from 80V to 85V Constant Voltage, and the Power draw of the NUBM31T was quite linear. This was the same to NUBM44(7W) single diode, it was quite linear. I believe modern 445nm diodes 5W+ are different from the traditional diodes. They almost behave like LEDs in terms of forward voltage curve.

When you say "sensitive" Do you mean slight changes in Vin would have large amperage draw effects? Or maybe life expectancy due to voltage spikes, etc?

If I were to use the Drok converter as the driver, what would the potential issues be compared to a "true laser driver"
Examples;
-Voltage fluctuations causing laser diode to wear out.
-Efficiency of "85%" compared to real drivers at "97%"

The reason why I want to avoid using 4 separate buck drivers is because I want to control output with a single manual POT. I wouldn't know how to control 4 drivers with a single pot without having to make a custom PCB.

I don't need clean PWM/TTL pulsing required for laser etching or other similar purposes. I would just turn it on and adjust the current as needed.
I really want to use the DROK driver since it will save me so much time. I looked for hours and was ready to pay up to 1000USD for a driver and nothing was suitable.
I am open to commission a driver to be design and made, but not many people out there would be willing. If I could customize, I wanted to add thermocouples, etc to have even higher safety.

Is there anything wrong if I were to add a 4/5A fuse inline with a driver to protect incase of anything?
I have (accidentally by killing a live-lasersystems.net driver) tested on the nubm31t with short bursts up to 8A and it did not die.
Few things:
They may behave like LEDs in terms of their forward voltage curves but for LDs forward voltage changes can be much more destructive cause they will allow much more current to flow.
Most "real drivers" are in the 85-95% neighborhood which is very dependent on topology.
There is nothing different about those diodes compered to others. Also FYI you should never EVER run any short of laser array in series because if a diode fails open it will instantly over-volt all the other diodes massively increasing the current going to them and the driver wont have enough time to compensate for that. Do as I sad with the 4 drivers in parallel or a single high current 25v cc source. All modern drivers support pwm so if you want to use 4 buck drivers in parallel you can use a single PWM signal do modulate all of them.
You can add a fuse but even a fast blow one wont be fast enough.
To protect your diodes you can use either a lasorb or a zener clamp with a esd protection diode

I lied a bit, when driving a red array my 3A buck drivers(20mv p-p) hit a whopping 97.6% mark in terms of efficiency. Also for my array I always keep the input - + and positive wires shorted when not in use to prevent any change of a voltage potential building up between the pins or an esd discharge.

IMG_20201109_123204.jpg
IMG_20201029_202033.jpg

#Don'tForgetAboutRed We are all so spoiled with all the exotic diodes that red diodes don't get much love nowadays..
 

Light superglue

Well-known member
Joined
Feb 12, 2016
Messages
573
Points
63
Hi guys,

Let me add a little of words to your talk. Last months I tried to check several options to drive NUBM31. The final devices will take a lot of time to be built but when driving laser arrays I prefer to know the numbers (voltage, current). The drivers you show are compact and not expensive but they have no screen! Maybe good for super compact laser pistols but I doubt...
At the moment the best driver with screen I found is BST900W from ali. Pretty big but super cheap. Other drivers are crap (I tried 600W drivers etc.).
I have only checked it with one NUBM31 but acc. to specs it could drive 2 of them in parallel. This is still to be checked...
 

likevvii

Member
Joined
Mar 2, 2020
Messages
67
Points
18
If I run it all in series, how often would a diode fail? I don't mind if it fails after about 20 hours of use.

I have this driver:

I really like its 97% efficiency. However I need to run all 4 channels in parallel. I thought of putting a fuse on each channel. Would there be any immediate practicallity danger levels by doing this?

I understand many things can happen, however I do not understand the risk factor of each. For example, voltage ripple in my mind sounds like a small deal, but maybe I dont fully understand and it is a big deal. The opposite goes for adding a fuse. I think a fuse is a great idea to significantly increase safety.

I'm just trying to have fun so I don't need anything "professionally" done. I just needs to work within reason. 20 hours of total ON time would be all the array ever sees. I am prepared to test and break things.

If I were to use 4 drivers for each channel, what do you recommend I use to control output? Can all 4 drivers share the same CC/CV POTs in parallel? I dont want to have to twist 4 pots each time.
 
Last edited:

Devil_Master

Member
Joined
Feb 25, 2009
Messages
170
Points
18
Im not too experienced with exactly what is a good driver, but I plan to use these
Drok booster
The pictures and reviews on that page are not encouraging. I quote:

"bought this unit from another seller to charge my 72V AGM BATTERY BANK via 300watt solar panels with a 40 volt input, this unit did not come with instructions, when the sun got shaded the uvlo led became lit then suddenly brightened when the sunlight intensified, the four input 470uF 63v caps exploded violently nearly buring down my house, the boost control circuit caught on fire as seen in the 2nd pic, funny thing my batterywas being charged at 3amps, my 10Amp external fuse didnt even blow, worst case i did not get any support from the seller much less of a refund "
 

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