HAve a circuit, use 3-8 ma,
3 when lights is out, and 8 when lid.
blink every second,

How long will 3 * 1,5 v AA battery hold the circuit running ?
And if replacing by a 9v battery and a 78L05 ?

Rgds
ForceMaster

 

The capacity of typical AA and 9v batteries are:

AA - 2000mAh
9v - 500mAh

http://www.techlib.com/reference/batteries.html

 

An old 78L05 regulator uses a maximum current of 6mA when it is not doing anything.
Use a modern 5V regulator instead that has a very low current.