I am having some trouble using Triacs in order to dim a light bulb operating at 220V AC, I am a student at school and I don't have any background about using Triacs or Diacs or so, so I seeked the internet for circuits which uses a microcontroller in order to control the Triac to control the speed of an AC fan or brightness of a light bulb. So I got this circuit which I understand it all except there is a part I didn't understand in the circuit so that's why I am asking here for help. So my question is concerned about this IC the MCT2e which I think is an optocoupler, how can this IC detect the zero crossing in the AC wave ? Although the input in this IC is rectified using a bridge rectifier ? And also what is this IC properties ? Can any general purpose optocoupler be used or there is special specs. For it ? in short I want to know the principle of how this part of the circuit works in order to detect the zero crossing point in the AC wave.
Thanks in advance.