Laser driver from PrintrBoard

[alieneskimo12]

Hey guys,

This is my first post here, so thanks in advance for your help! I have a Printrbot with a Printrboard Rev. F board driving it that I would like to use to control a laser driver board. I am interested in the 0-5v TTL laser driver from China that is prevalent on eBay. I already have a 3.5 watt 445nm laser diode that I want to drive with it.

After many hours investigating I have narrowed my options to three. Reducing the PWM fan output signal to 0-5v to drive the diode board, adjusting the firmware to specify a 5v pin for the fan output instead of the current pin, and moving to one of the 5v extension pins.

My problem is I can't seem to come up with a complete plan to pull off any of these three options. From my multimeter testing I get 6 to 12 volts from the PWM fan pin from 0 to 100 percent. I'm not sure how to use a voltage divider to drive this to 0-5v. For the firmware and pin changes I can't seem to find complete enough documentation for a pin out. If I find a pinout and move to extension pins how do I control these with the Printrboard m-codes?

Thanks guys!

[RetireeJay]

I don't know much about laser driver boards, but it appears that many of the boards use 12V as their main incoming power, and use "TTL" (5V) to turn the laser on and off.

If your board requires a 5V power supply, then use a 5V power supply. The red and black leads coming from an ATX supply are 5V and can supply lots and lots of clean power. The fan output from the Printrboard is pulse-width modulated 12V, and it is not a "clean" 5V even if its average is 5V. It's not intended to supply power to other circuits.

The Printrboard itself has an on-board 5V regulator, which draws power from the incoming 12V - but the on-board regulator doesn't have a lot of extra capacity, so I do NOT believe it will work to provide all the power that your laser needs. Get your main source of power for the laser directly from an ATX or other true power supply.

On the other hand, if you are wanting to use the fan output to go to the CONTROL input on your laser board, that's another story. Some of them will probably allow 12V on the input, even if it's labeled "TTL". But the way that the fan output works is this: one terminal is at a constant +12V, and the other terminal is switched to ground under firmware control (pulsed). So you could use a resistor divider from the 12V to get a 5V switched signal for your laser board - assuming that its input is high impedance. Then you could control the duty cycle of your laser with G-code anywhere from 0 to 100%. I can sketch up a circuit for this if you want. You will have to find a ground connection somewhere on the board to make it work. Are you using the X, Y and Z motors and endstops, or is Z not relevant to using a laser? I ask because there could be a handy source of ground at the unused Z endstop connector.

[thawkins]

[alieneskimo12]

Thanks for your responses guys! RetireeJay, unfortunately I am using the Z stepper and end stop. I am essentially wanting to create an all in one 3D printer / laser engraver. Is there anywhere else I can find a good ground? I am wanting to use the Printrboard only to CONTROL the laser driver board. If you wouldn't mind drawing me up a circuit that would be much appreciated. I am certainly in the "enough to be dangerous" electronic skill crowd.

Thawkins, I understand your approach but you may need to spoon feed me a little more. Would I determine the resistance to the 12V rail with a multimeter? Not sure how I get the 5V from the pull up resistor either.

[RetireeJay]

OK, here is a schematic which should do the trick for you. You can use the +5V supply on the Printrboard for this.
The X and Y "endstop" connectors have both ground and +5V available; the Z connector may be either +12V or +5V depending on the sensor in use. There are also points with 5V and ground available on the Extension headers. Please look at the schematic available in the RepRap.org wiki.
The transistor shown in this schematic is the Fan MOSFET that's already on the Printrboard, which already connects to ground. So the only new component you need to add is the 4.7K resistor; the rest is wiring.
Printrboard Fan Output to TTL.PNG

[MrFluffy]

theres an article on Hackaday about this topic that might be relevant if your still working on it.
http://hackaday.com/2016/03/03/etching- ... printer-2/

[ManusH]

There is a blogpost: (Had to remove the link because of forum restrictions, but it is in: polakiumengineering (dot) com )
And a Thingiverse share for the parts ( thing:601854 )

for the same purpose: Turning Printrbot Simple Metal into a Laser Cutter
which I am also intereste din

But I can't see the detail for connections between laser, laser driver and Printrboard.
The only infos I can find in those pages are
- "This is responsible for modulating the laser power via M106 gcode commands." sentence with 2 photos in the blog-post!
and
- "The two-pin laser cable connects to the output of the laser driver. The input to the laser driver is split from the pwm fan output of the printrboard." as an answer in the comments section.

No schematics or detailed photos of the connections available.

Btw; I bought a laser-module but no driver with it; so I couldn't test it yet myself.
Maybe it will be useful for you!

[Mooselake]

You hook the laser up to the extruder's cooling fan connection on the printrboard, then use M106 to output a pwm signal to the laser's ttl control input.

This is a potentially risky activity, more so it you want to keep seeing things out of both eyes. If that's not sufficient information to allow you to connect the laser then find a friend to help you who does understand. This is one activity you really don't want to do wrong.

Where in Turkey are you? One of the big online laser sellers in is Turkey.

Kirk

[endurance-robots]

Our customers often ask us how to connect a powerful laser to this or that CNC machine or plotter, if the circuit board of the device does not have a separate power supply for a laser, and the current going through the control board is minimal and does not exceed, for example, 0.5 A.

The DIY и MakeBlock engraver board is powered with 12V and 0.5-1 Amps, not more.

Remember that 1W diode (solid-state) lasers requireapprox. 1-2 А и 12 v current; 5 W lasers and higher need more than 3 A.

Our 8W (8000 mW) diode laser needs 4-5Amps and 12 volts.

To mount a more powerful laser on a plotter (such as a MakeBlock XY plotter 2.0 KIT) or on a small Neje engraver additional power supply is needed. It is possible to install a separate battery unit and a driver, for instance.

We share with everyone an open hardward schematics

Endurance circuit MO 1 schematics



Connect the laser control to the МК and GND1 pins. The supplied power must not[/img] exceed 24 v. Connect the laser «+» to «+12v», the laser «-» to the «Drain» of the field transistor.

The GND1 and GND2 contacts may not be necessarily located on the same line. It is possible to use the «+12V» and «GND2» contacts of the lead-acid battery.

It is enough to have a bread board of 20х20 mm to place all the elements.

This schematics furnishes

12 v lasers with the current up to 5 A.

Use the current powering the DIY or an additional battery unit.

The schematics connection

Looks like this

[endurance-robots]

if you need a driver for laser and TTL
have a look at this solution