The output is controlled by PWM signal (green)
The saw reference waveform is (blue) compared to the error voltage (yellow). This control the duty cycle of the PWM generator.
You get info about the duty cycle on the 7 segment display according to the load of the output(red).
You can change the load with the three switch and check if the pwm duty cycle changes and the display is changing.
Red and green LEDs on the left show if the control loop is increasing or decreasing the duty cycle and of course the output voltage.
