How to make automatic DC and AC phase changer circuit - homemade auto switch

in this video we learn How to make automatic DC and AC phase changer circuit easy at home. sometime we want when light goes then battery power automatically connect with led or any output object then we need automatically phase changer switch. and its perfect for automatic line changing. its combination of 2 relay.
its 2 input and one output switch. we try to explain every thing easy steps with circuit diagram watch and make same.
thanks.

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