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Can cheap Chinese CC CV modules be used as laser driver?

Simonas

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I'm looking for a very cheap and power efficient alternative for LM317 or LM338.
My only worries are that the module may produce voltage pulses when turned on/off.
Has anybody tried to use them?
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RedCowboy

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I'm looking for a very cheap and power efficient alternative for LM317 or LM338.
My only worries are that the module may produce voltage pulses when turned on/off.
Has anybody tried to use them?
View attachment 72224

Some led flashlight drivers can be repurposed quite well, but the variable dc to dc general purpose units like in your pic from China can induce a start up spike.

 

Simonas

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What if I were to put a film capacitor on the output to smooth out the spike, and a zener diode to make sure the supply voltage doesn't go over the max LD operating voltage?
 

Simonas

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I did some tests with a random buck converter module and it shows some really good results - no spikes when turning it on/off.
The module was set to 10v, and the load was a 10ohm resistor so there was a current of 1A flowing, module input was 20v.
NewFile2.pngNewFile1.png
 

RedCowboy

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In the case of laser diodes we must regulate the current, simply limiting the voltage won't prevent blowing your laser diode.
 

gazer101

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By all means if you have a scope buy away and test them for spikes before hooking them to a laser
 

FireMyLaser

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I have a very similar looking board to OP (using XL4015E1 chip) which I can test. It's just been sitting in a drawer unused for years.
 

Simonas

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In the case of laser diodes we must regulate the current, simply limiting the voltage won't prevent blowing your laser diode.
I know that, I did a test on an ordinary buck converter to see if the buck converter design doesn't produce voltage overshoots, now I've done tests with the most common buck converters (I tested 6 models), and it seems none of them make overshoots, now I just need to get that CC CV module and test it, then I might look in to some of the boost modules.
 

Simonas

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Nope, those CC CV modules won't work :/ , then turned on the module briefly provides the set voltage and only 150ms later goes in to Constant Current (CC) mode. The module may do the job if the set voltage is very close to the LD operating voltage, else the LD might not survive the 150ms of overcurrent.
The oscilloscope shows that the voltage rises for 150ms until it reaches the set output voltage of approx. 20v, then the module starts going into CC mode and is adjusting the voltage to meet the set maximum current of 1A and finally, the voltage finally drops down to 10v.
NewFile4.png
 

FireMyLaser

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I tested two cheap drivers, and took some measurements. Excuse the crude screenshots.

This one is based on XL4015E1 chip, and has adjustable constant current and adjustable constant voltage.
For these tests I set the voltage to 8.0V, and constant current to 500mA.
V-in is a 3-cell LiPo, fully charged to 12.6V.
Output is connected to a diode dummy load, set to ~5V.
1 5A driver.jpg

Setup:
2 setup.jpg

Each test is repeated with a RC-filter, made of 1 ohm resistor, followed by a 100nF MLCC, and 100μF electrolytic cap.
The filter is placed near the load.
3 RC-filter.jpg
4 RC-filter.png

Startup. Like Simonas' driver, this one also overshoots, but the filter helped a lot.
5 startup output voltage, v-out 8v, 500mA, 5v load.jpg

Output voltage ripple. Again, the filter was helpful.
6 output voltage ripple, v-out 8v, 500mA, 5v load.jpg

The other driver uses XL4001E1 chip, and is fixed constant current at 350mA.
It also has PWM input, and the output current can easily be changed with other resistors at R1-3.
1 350mA driver.jpg

Same setup as before:
2 setup.jpg

Startup.
3 startup output voltage, 350mA, 5v load.jpg

Output voltage ripple.
4 output voltage ripple, 350mA, 5v load.jpg

I think cheap drivers can be fine if you add a rudimentary RC filter, or maybe just caps over the laser diode pins.
The values I picked are just my go-to for initial testing, and are perhaps not by ideal for any application,
but shows where things can be tweaked if need be.

As for the availability of these drivers, I don't know. I got these maybe 10 years ago. I don't have their model numbers or such. If anyone wants them, then use the pictures for reference when searching the chips.
 
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Light superglue

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You driver seems to have same parts as one which I have used 5 years ago to drive 2 PBS-combined NUBM08 (needed 9V) mounted into a screwdriver body from its 12V Ni-MH battery. CDBeam called it Steampunk laser back then.

The small driver was fom Banggood and had CN4015-2 mark on it, now when googling I find this - must be newer version:
 




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