Which Latching Relay Should I get

I need a Relay that will switch automatically between using (2)AA batteries and a 3V wall wart. 50mA is the max current through the circuit. So, when I plug in the wall wart while the circuit is being powered by the batteries, it will switch to the wall wart for power.


A double-throw relay with 3V coil driven from the wall wart input could likely be used for the purpose, though there are also a number of purpose-specific ICs made for this task, as well as the possibility of building the function oneself from discrete components.