Simple 5v Battery Backup Circuit

It’s a simple 5v battery backup circuit with constant slow charging facility. Its mostly suitable for microcontroller projects where we need constant current source without any cut-out. Whenever mains fails the battery takes the load without any delay again when mains restores batter goes to charging mode again. Its not just a idea or diagram I developed this circuit for my own (my digital clock need’s constant 5v power supply) and still using this, till now without any problem. Make the circuit and if you face any difficulties just give me a call