Controlling AC loads power is important application in many areas. We can control the power of a device by firing the triac at specific angles. For that we should know where the AC signal is crossing 0. Zero cross detector exactly does that..it will give a pulse whenever AC signal crosses 0. We can configure the controller in interrupt mode to capture this event and can fire TRAIC to control the power supplied to the load.
This is a simple ZCD circuit which requires only few components to build. Where ever you have tasks that depends on the Zero cross of your AC power you can use this circuit.