Hello,I am trying to control the AC Load power with a microcontroller but I am not succeeding on determination of the zero crossing detection,I am using 4N25 for determining the zero crossing after full wave rectification but I am failing to do this.

I would like to use a potentiometer but first I tried to set 3ms as period of firing angle but no success.
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Here is my circuit and codes in microc,could you please help

 

Please post your question in this forum rather than directing to a forum off-site. .

 

See Fairchild AN-3006 for zero crossing switching and phase angle control using the correct opto.
Max.