INDEX

Generation of PWM:
PWM can be generated using IC555 or using microcontroller or computer parallel port. Now you try to generate PWM using IC555,remember that Ttotal should remain constant.

Here you can see that i applied a variable resistor. So when charging occurs it charge through upper part of variable resistor,diode and capacitor path. When discharging occurs it discharge through lower part of variable resistor and capacitor. So the total R=Ra+Rb=variable resistance, so Ttotal
remains same.