How can I sense induced voltage by wrapping a wire around the spark plug cable of a petrol engine. I have a a car alarm system that can remotely start my car. It came with a device that has a wire that you wrap around the spark plug cable to tell the electronics that the car has started. This system is sealed up by the manufacturer so I can't access the cct. I need an output that I can amplify to drive a 12V relay. Anyone with an idea? Thanks