This is a 9v battery status indicator circuit.One of my friend asked me to build this as he wants a 9v transistor radio battery status indicator. Thats why i build this circuit it works great and another thing about this circuit by changing the 'ZENER diode" you can rebuild this circuit for other low power battery. I used Green and Red led as green Led light's up when the voltage is upper than 6.9v and Red led lights up when the voltage drops to 6.9v . Its simple and reliable all the parts are commonly available and low cost also.
parts List :
Led (RED & Green )
ZENER 6.2v (for using with 9v battery)