I have made a circuit which needs 5v to operate, I want to give 5v supply to that in portable and compact way. I didn't find any battery with 5v specs. I managed to run it with 9v battery in combination with 7805 voltage regulator but that battery is too heavy, bulky and I don't want to waste 9v for getting 5v only. Please let me know most compact and efficient way of supplying 5v voltage to a circuit.
P.S. Can I use 3v coin cell to run that circuit. Is there any way to step up from 3v coin battery to 5v?