Garage Door Hacker in practice
It requires that you already have the remote control and that the code is entered on a numeric keypad.
It would be useable on any style of door that has this type of control ...
UNLESS
Modern systems may contain logic to allow you, say, four attempts and then just ignores you for ten minutes before allowing you to try again. As this hacker circuit stands it would just keep trying and more than likely 'guess' the correct code while such an intelligent reciever was ignoring you - you would then never be any the wiser 8)