Digital K40 laser power control.
I have been wondering for a while now how the digital power control works on my laser machine, its the usual digital kind with three seven segment LEDs. I have heard people on here refer to the control board as a digital potentiomenter which I thought was unlikely.
The reason for doing this is because I’m wondering if it will be possible to incorporate the digital control board into an upgrade using smoothiware which also has PWM control. I imagine the two PWM controls could interfere with each other. I may decide to ditch the digital board altogether and replace it with a preset potentiometer to set the absolute maximum current at 18mA. I think this could be used as the input voltage to the smoothie PWM level converter input, I’ll have to try it and see.
Today I have connected an oscilloscope to the control input terminal on the power supply to measure the signal. It is a PWM signal. The video shows it when I increase the power in steps of 10% from 0 upto 90%, finishing back at 0%. The noise is my air pump which is fed from the PWM and only turns on if there is a PWM signal present.
An observation is that when the control board was set to 40% the pwm signal had a 50% mark to space ratio. The control does not appear to be linear, I wonder if this is intentional. Also it is not possible to achieve 100%, 99.9 is the maximum achievable - good enough for all practical purposes I suppose.
hth David.