The zero-cross is the method in which we receive the change in the frequency signal of the AC voltages. In IoT especially home automation or heavy load control, we need to control the AC load by the effect of change in frequency. The optocoupler has many uses but due to increasing in IOT field from 2012 the optocoupler is now increasingly using in daily life to control the appliances.

The manually made Optocoupler has low voltage operating voltage level as compare to this PC817.

The closed communication protects it from many things especially from temperature too.

First manually made circuit comes in a larger size, then in case of IR receiving devices the circuit IR sender of auto coupler or receiver could be affected by other IR signals.

The Optocoupler is just a small-sized circuit of infrared receiver and sender but in case of making it with externally by using IR sender and receiver cause many problems. The circuit is totally simple but the resistance will give it protection at the input in HIGH voltages. Whenever the IR signal will be generated at then the logic state will be changed from 1 to 0, due to change in the flow of current.

The optocoupler at input requires current limiting one resistance but at the output, we will need to connect the logic output pin with the power pin. The working of PC817 is very simple but to use it with different devices comes with specifications. These are the alternative options: 4N25, 6N136, MOC3021, MOC3041, 6N137 PC817 IC Equivalent It will be used to make the common ground with Power supply and the circuit. It will give the logical output by receiving the IR signal. Pin 3 is an output pin of the internal IR receiver of the optocoupler. It will give the IR to make the common ground with the circuit and Power supply. Pin 2 is the cathode pin of the IR within the optocoupler. It will give the logical input signal to the internal IR. Pin 1 is an anode pin of IR input within the Optocoupler.

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