The circuit pictured here does just that. The mains 220Volt voltage is led through two 30k resistors to a bridge rectifier that gives a double phased rectified signal to a 4N25 opto-coupler. The LED in this opto
To convert the AC voltage to DC, usually a full bridge rectifier is used. This is essentially four diodes arranged so that the positive half-sine of the AC waveform passes through, and the negative half-sine is flipped. The result isn't quite the same as a constant DC voltage, but clos...
the bridge rectifier is producing DC from the AC, so anything after the bridge is DC, and does not have a sinusoidal wave for the zero point to detect. Your just wasting components and potentially endangering your life by messing around with mains voltage when you obviously have no idea ...
the signal is rectified with a full-wave bridge rectifier. Immediately after the rectifier, the signal is driven to the zero-cross detection circuit. A large capacitor (C1) is used to smooth a part of the rectifier's output power. This will be used as the power supply of the rest of ...