Need to make a auto disconnecting cicuit.

[mariah1902]

I am currently trying to make a circuit for my phone which will automatically disconnect the circuit when the phone will be fully charged. The circuit has to run by dc supply. Also it would be helpful if we can set a time for example if we set 3 hours then the circuit will disconnect after 3 hours. How should I make it?.

 

[BradtheRad]

My flip phone beeps when it's done charging. Does your phone do the same? Then audio detection is probably the easiest method to trigger a disconnect circuit.