Hi Dave,
You misunderstood my explanation. I am not looking alternate option if my mains fails.
As I have mentioned in my previous post, I am looking for design of P.S. circuit which has only "one input" and that should take any incoming power, AC or DC.I am still confused as many people have already told me I could design "Single Input" power supply but you are saying that I cannot design the same. Why?
I agreed with you that there should be some switching or sensing circuit to differentiate AC and DC. But many folks have already told me, no sensing or switching circuit is required.
I am totally confused at this point. (Because I am getting inputs from both the sides, positive and negative.)
Thanks for looking into my post,
pj