Welcome! Log In Create A New Profile

Advanced

Stupid Question about 2.5W laser

Posted by PDBeal 
Stupid Question about 2.5W laser
April 17, 2019 12:03PM
Right, so I recently purchased this 2.5W Laser from Amazon and have received it. When looking at it, it only has a plug and a small cooling fan on the back side of the laser module. It came with a 120V/12V wall plug to connect to the laser.

Is it safe to assume that I could just wire this plug into the RAMPS 1.4 board as if it was a hotend heater, heatbed, or cooling fan and run PWM? I was sort of expecting my laser to have power and some sort of control signal that would turn it on or off, but since it appears its just power I'm assuming what I expect should work? Either way, if this does function that way, I may splice the cooling fan to be always on and just PWM the laser power itself.

Is there anything else I should be looking at to control this or will what I think work?
VDX
Re: Stupid Question about 2.5W laser
April 17, 2019 01:59PM
... inside the module housing should be some sort of constant current regulator - mostly an (overpowered) LM317 with a shunt resistor, sometimes a bit more elctronics around.

If it's "safe" to PWM the constant current driver, should be tested - some layouts tend to produce short high current "spikes" with much more current - had a driver for 4 Amps, that generated +30 Amps and -15 Amps spikes, when switched !!!


Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org]
Call for the project "garbage-free seas" - [reprap.org]
Re: Stupid Question about 2.5W laser
April 19, 2019 12:56PM
Better to get laser with TTL trigger
Power laser via 12V supply
ON / OFF PWM via TTL

Return it get a laser with TTL trigger

confused smiley
Re: Stupid Question about 2.5W laser
April 28, 2019 05:49PM
So, looking at the laser, I took off the fan on the back and see this little circuit board. As far as I’ve tested, the laser module is on when it has 12V from the P+ and P- pins on the little circuit board.



Any idea what C+ and C- would be used for? Any idea how to slide this out of the heat sink to see what else is on the control board? I’ve already tried to push it up from the lense side but it doesn’t seem to want to move. I’m not opposed to breaking it to get it out to change how it’s controlled, but figured if someone knew before I start randomly pulling on things.

The part number on the side of the laser M-33A450-2.5W-G doesn’t seem to show anything but other places selling this module.
VDX
Re: Stupid Question about 2.5W laser
April 28, 2019 06:11PM
... most likely there is some sort of a pretty cheapish constant current regulator inside (often only a LM317 or LM338 and a shunt resistor) ... the C+/C- should be a capacitor ...


Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org]
Call for the project "garbage-free seas" - [reprap.org]
Re: Stupid Question about 2.5W laser
May 30, 2019 01:57PM
Quote
PDBeal
Is it safe to assume that I could just wire this plug into the RAMPS 1.4 board as if it was a hotend heater, heatbed, or cooling fan and run PWM?

Not a silly question but certainly not a clever assumption also. You should check with the vendor. I recently purchased a 5W from Amazon and while the laser runs on 12vdc, but the PWM/TTL is 5vdc Peak/Peak and a max of 9KHz.

I believe that some vendors advertise PWM/TTL and suggest using the Fan or Heater screw terminals for that. But the TTL protocol **means** 5vdc max. In that case use the input lead to the MOSFET for the Fan/Heater pin you define. That will be a 5vdc signal driving the MOSFET.

BUT, asking the vendor would be the BEST first step.
Sorry, only registered users may post in this forum.

Click here to login