Changing the wiper potentiometer position change duty-cycle. This can be used to control DC engines, lighting and many more... from a min to max values of power. Put a driver on output to highests currents.
ADC + DISPLAY show us the level power from 1 to 15 (F).
555 CIRCUIT:
With this circuit you can get a constant frequently changing duty cycle as you want.
Very stable.
R1 = R2 = 2'5℅P1
D1 = D2 = 2N4148
C1 = Japanese
All R -> High PRECISION <1% if it's possible
555 -> NE555, SA555, SE555
