I need some help to design an automotive type circuit. It will consist of two 12 volt inputs, and one 12 volt output. The first input will always be on. The output should also always be on unless the second 12 volt input comes on. When that happens I want the output to drop to zero for until approximately one second after the the second input turns off and remains off. When the second input does come on, it will turn on and off in about one half second intervals until it shuts off completely. Thanks for your ideas.