AC Phase Control

I am planning to control the intensity of a bulb according to the input from Light sensor LDR. I had done a lot of search. But sill in confusion about how to detect Zero crossing. I found a link on the Arduino. But there is circuit diagram. any one if done successfully , please share it.


Although new, but you may try is, use Relays and some capacitors which stores charges until some amount of volts it gets, even don't know it's names and even some diods are there which limits or gives desired/fixed voltages and may use pots which may supports AC...

Silly... Please ignore if you don't get any clue from such answers... Just to divert mindsets to get more idea !!!

You need to have a zero crossing detector fedding a signal into the int0 or int1 pins of the Arduino, then inside the interrupt service routine you control a TRIAC.
See this links:

See the second image, the one that is isolated from mains via the transformer, there are more ways to do this, but this is a simple and safe one.

The Zero Crossing detector detailed here :- has a number of advantages.