I have read a lot of articles on pulse width modulation and I am none the wiser as to how it generates different voltages by simply varying the pulse width of the waveform. What I read was that if you have a rectangular wave train of some amplitude and change the 'ON' period the "NET" voltage also changes! I don't understand what it means by "NET" voltage. If you have an LED and if you apply the same pulse train at some frequency then shouldn't the LED simply turn ON(+V volts) and OFF(0V). Why do we have a dimming effect? Also, based upon this explanation can anyone derive the expression of the average voltage i.e (Ton/T*V) volts. Why is it a ratio of Ton to T?