Homebrew Laser Cutter made by Zach Radding

Step 7 PWM generator

This tiny PIC16f675 microprocessor board runs the the control panel as well as pulse width modulating the beam (PWM varies the apparent laser power thus changing the depth of cut).
This processor looks at the step and direction signals going to the stepper motor controllers.
From this it deduces how fast the workpiece is moving and adjusts the laser power to match. Faster motion,
more power. Circles and other curves cause the machine to move slowly as it approximates the circle from a series of tiny line segments. Then the laser power needs to be turned down to match the slow speed. This is more important when etching images onto something than when cutting things out.