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Hi all,

I would be very grateful if someone could help me with an electronic problem regarding CNC and wanting to use a laser. I am an electronic dummy so please bear with me. I have a cnc machine running perfectly driven by a spark concepts x pro V3 board, powered by a 20v desktop power supply. I have bought an endurance 8w laser which I want to control via the spindle speed output from the cnc board. The laser requires 12v desktop power supply. From the laser there are three wires, two, + and - power, and a further white wire which I know is the connection for PWM. The issue is that there will be no ground wire returning to the board from the PWM signal as the two power supplies are separate and I am aware that the board needs a - return. If my perception of the problem makes sense any help would be appreciated, I have scoured the net but much of what I have found I don't understand anyway.

Merry Christmas all, whoever your god, and thanks for any help.

Paul.
 

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You may be able to connect the 2 grounds from both power supplies together. Now if there is a chassis ground and a digital ground and if the 20 VDC power supply is digital ground and the 12 VDC power supply is chassis ground you should not tie them together.

CAD-Man
 

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Discussion Starter #4
Thinking about your advice, would it make sense to use a dc/dc converter to get 12v off the 24v psu, therefore using the same ground ?

Merry Christmas

Paul.
 

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It might work, but you would have verify that the ground output on the DC to DC converter was common with the ground from the 20 VDC power supply. First try this, with power off and power disconnected from both supplies start ohming out the ground connections in both systems and see if the are any grounds are common between both systems. If there is, your ground return is already there. It would be nice if I could see the schematics of the system and maybe I could see where you are coming from.

CAD-Man
Bruce
 
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