Laser module 12V can it run PWM

[PD0RUZ]

Hi,

got the A3 laser engraver from china with the eleks L7 board.
Use T2laser and PWM jumper setting 0.9 Gbrl.
Use firmware pwm 1Khz. I can see that it controls the power of the laser module,
but engraving settings for laser power is now 0 ~255. It's engravings a little light.
Does this module support PWM.. knowing it's a CC driver input 12V
Laser module in atachment...

Advice please. Don't wanna break the module..

[beikeland]

It varies quite a lot if the 12V modules can take a PWM. After all the modules job is to run a constant current through the laser independent of the supply.

You could try tweaking the PWM frequency of Grbl and see if it helps. But it will never be as linear as a true TTL enabled laser no.

[Zax]

As beikeland said, it won't be as good as a TTL module but you should get some power control.

It depends how quickly the CC driver can switch, or if they installed a slow start capacitor (which would kill your PWM).

[PD0RUZ]

Tested it with settings from 0~255 it starts burning @180 and has max power @255.
Conclusion: this type of laser module isn't capable of running with pwm signals..
So have to build a Pwm circuit for the laser, ore buy a 6Watt TTL Laser module.

Don't know what's ot gonna be right now. Left the settings for the laser @off 180 and full power 255.
Works, but not great!!

So if anyone overhere hasn't tried it yet, with this kind of laser don't bother to try.. it doesn't work properly!!

Thanks for the info.

[beikeland]

Yeah, you could always do both

The lasers are quite ESD sensitive devices so if you do attempt to disassemble take some ESD precautions. And you could always buy a TTL driver and replace the internal driver in the original module. I intend to that once I get a working replacement from Banggood; its not very well documented but if you search there is a post with some pictures at least.

But I experienced some improvement by changing the frequency of the PWM in the Grbl source code and uploading it using the Arduino IDE again. Might be worth a shot - but its still no where as linear as a true TTL would be, yet quite usefull after some experience.

[Zax]

As the laser heats up the response may change, so it may switch on at lower values. Just keep that in mind.

[PD0RUZ]

Thanks Guy's

looked at the post concerning the ttl driver with LED2001.
Who developed these boards. And where i van get one to assemble myself.
Got allready all component's.,...

[Agastar]

Hi that would be me I have the link to the latest revision source in my signature.

Hopfully this will be the last revision for this board. When the new boards come in I will be assembling and testing it and and will post the results. Once that is done, We'll be offering kits, assembled boards and complete laser modules for sale. The design will remain available and open for others to build themselves.

There are no restrictions on the design so feel free to modify it. It was built using Kicad and if you have any questions about the design or why something was done a certain way, please let me know and I'll help you out any way I can.

[Agastar]

I forgot to mention, Analog Devices has a nice article on smart led drivers using buck converters and they mention when switching the regulator on and off like we do with these Eleks boards that it works better when the PWM or TTL frequency is bellow 1khz. GRBL uses 1-8khz depending on which version you use which may help explain why it doesn't work so well. That and the soft start that Zax mentioned is probably the top two reasons.

[beikeland]

At which point does feed rate and ttl frequency start to become an issue?

1kHz and 5000mm/min is only  0.08mm/Hz sounds like it could benefit from being more. Just checked my laser and I've set it back to 7.8kHz as it seemed to give better results for me before I installed a proper ttl driver.

[Agastar]

that is a good question. It's something I've thought about but I don't have any test data on it yet.

[ggallant571]

mm/hz - Never heard that unit before but I have also been wondering about that ratio and have spent the afternoon playing with firmware. Upped the frequency from ~1KHz to ~8KHz and:

1. The intensity seems less for the same %.
2. I use a digital weak laser and it is easier to focus with 1/8 the on time.

There has been some rippling in recent etches that I was attributing to wood grain and/or too tight a focus. Will try on plastic with different rates.

mm/hz - the "Beikeland Ratio"

[Agastar]

mm/hz - the "Beikeland Ratio"

I love it! I'm going to add it to my signature

[beikeland]

Thats just gonna get confusing as is already defined as the scale of which to measure the number of output transistors blown in a amplifier. After setting a high score my teacher decided it needed a scale to be named after me.

[Agastar]

Lol, too funny!