Author Topic: Calibrating 5A Laser Diode Constant Current Driver Help..  (Read 361 times)

alexeinz

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Calibrating 5A Laser Diode Constant Current Driver Help..
« on: March 04, 2019, 07:59:28 PM »
Hi guys, sorry if I am not in correct board but looking for some help..

I have one of those 5.5W Chinese lasers with a separate 5a Current Driver ,
Original driver was DOA so they sent me a replacement but I suspect its not calibrated and not outputting the right amount of power.
I would probably say its comparable to 2.5W right now ( I can cut paper on multiple passes at 200/100% and I get very very precise focus and very thin lines , but its nowhere near the expected cutting power of 5.5w)

Focus and TTL was all measured and working correctly on my Mana as well ( I have eleksmaker ttl to pwm as well but tested directly with psu to laser driver too ) , so the last thing to test is the driver board..

It has a potentiometer but I am not entirely sure what would be the adjustment procedure / expectation ... does anyone here have any insight into these ( they seem to come with many of the cheaper diodes ) ...

Is there an easy way way to test it with multimeter and what should I be expecting to make sure my diode gets enough juice.
I have been reading about test load assembly but not sure which one I would need to test a 5.5w laser load.

If that too fails, I would need to get new ( hopefully higher quality ) module ... but rather make sure I tick all boxes before doing that.
the final goal is to cut some 2-3mm plywood and cardboard for my art projects with a bit of engraving on the side.

ggallant571

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #1 on: March 04, 2019, 08:31:29 PM »
Assuming the diode is 15% efficient then

0.15 * W = 5.5
or
W = 36 .7 Watts

So at full power you should be able to measure 3A at the power source.
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alexeinz

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #2 on: March 04, 2019, 08:54:32 PM »
thank you, sorry I am a bit confused ,... Shouldn't it be closer to 5a? And do you have any pointers or links that could let me figure if I could do it with laser connected or I have to build a matching test load

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ggallant571

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #3 on: March 04, 2019, 10:18:23 PM »
The power is measured in Watts. For simple DC circuits:

Power = Voltage * Current

You have the advertised power (5.5W) and the typical voltage (12V) and my crude estimate of electrical energy into laser power (0.15). I am not schooled in the construction of diodes and the 15% is based on my 5.5W module.
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Zax

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #4 on: March 05, 2019, 04:33:19 AM »
As a guide the Nichia 6W diode has a maximum forward current of 5A but in my experience you achieve maximum optical output at 3.3~3.7A. Increasing current just generates heat which reduces the lifetime of the diode. If you don't have a way to measure the laser output (optical energy) then you're somewhat shooting in the dark but to be safe 3A would be a good target.

alexeinz

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #5 on: March 05, 2019, 05:08:16 AM »
thank you, would the best location be to tap into the LD with multimeter or should I build a dummy load to test this ?

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Zax

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #6 on: March 05, 2019, 05:33:03 AM »
I always set it with the diode.

Here's my method. I use a bench power supply with current limiting and my laser power meter. I increase current and watch for the optical power to plateau, this is Imax and then I back off slightly (like 200mA) to increase lifetime.

ggallant571

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #7 on: March 05, 2019, 05:47:14 AM »
I guess there are 4 possible faults:

1. The PWM from the processor does not go to full ON.
2. The 12V bulk supply cannot supply the requested current
3. The laser power converter is insufficient.
4. The laser diode is faulty.

For the first three a well known dummy load would be nice.

About 18 months ago a user named agastar was attempting to build a diode controller board. I recall that he had dummy loads.

The is also the possibility that the module they shipped you is really a 0.5W diode with a 5.5W label.

I have 1.6W, 2.5W, 5.5W & 15W modules. The 5.5W performs the worst. The focus is really poor. Tried different lenses but the 1.6W cuts better.
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alexeinz

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #8 on: April 03, 2019, 11:01:50 PM »
Cheers all, bought dummy load board of eBay and verified correct load , also bought diode, LD and heatsink (nubm44) and built my own full laser module
Burns amazingly well and all parts were less than 200usd off eBay incl shipping to Tokyo


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Zax

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #9 on: April 04, 2019, 05:15:03 AM »
Do you have a laser power meter? Do you know what output you are getting, if not what current are you using?

I have used many nubm44's and they are very reliable at 6W but can be pushed to 8W easily with appropriate heat sink and fan (which I see you have), typically around 4.5A.

alexeinz

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Re: Calibrating 5A Laser Diode Constant Current Driver Help..
« Reply #10 on: April 04, 2019, 06:00:48 AM »
havent got laser power meter , but the driver is calibrated to provide 4.5A to the diode ( I dont need to run it at 100% though ) this laser driver has a meter output .
didnt realize how easy it is to build my own, too bad i burned cash on that chinese fake one...