I built a CNC router many years ago. It uses a Arduino/GRBL 1.1f controller. I ordered a NEJE A40640 as an add on. I know the PWM single has to be 12v. Does it need to be constant current, if so how much? Is it the voltage or frequency or the amount of on time that sets the laser power? What PWM frequency should I run at? Guess I should have just bought a controller board but was told all I needed was an amply 12VDC supply. If you could point to some DIY articles that covers all that it would be great. Thanks for the help.