[aprssig] backup pwr systems

[Ben Lindner]

Hi all,

What sort of backup power systems do people use these days.  ?

eg.

Running a rig from a standard PSU while charging a battery at the same 
time and when the mains power drops out the battery will take over and 
run the radio. Then when the mains power is returned every thing is back 
to normal, battery is charged again from PSU and radio runs from PSU.

Any body have any ideas on how to work this or has a circuit that I can 
build

Ben Lindner
VK5JFK