Problem of connecting smoke detector to pc using parallel port? We are making a thesis work and we are having a problem about this. Its when the smoke detector detects smoke it should send data to pc, and then the pc will automatically send message to cellular phone. The question is how will i connect the smoke detector to the pc using parallel port. I have a smoke detector with a battery 9v. How will i control the voltage which is coming directly to my pc so my motherboard wont ruined. Anybody who knows the schematic way? I don't know alot in electronics.