Sensors For Car Alarms - Sensors For Car Alarms can be added to your car alarm. Door sensors are extremely effective, but they they still only offer limited protection. There are other ways to break in to the car other than the door, such as by breaking a window. Thieves don't even need to break into your car to steal it from you. They can tow your car away as well. One way to detect breaking glass in your car and/or somebody opening the car door, is to measure the air pressure in the car and record any changes. Even if there is no pressure difference between the inside and the outside of the car, the pressure when opening a door or forcing in a window pushes or pulls on the air in the car, creating a brief change in pressure. The air pressure sensor in your car alarm will detect this change. Car alarm tilt sensors tend to have an array of mercury switches positioned at different angles. Some of them are placed in the closed position when you are parked on any sort of hill or slight slant, and some of them are in an open position. If a thief changes the angle of your car in any way, possibly by hiking it up with a jack or lifting it with a tow truck, a closed switch will open and an open switch will close. If any of the switches are thrown off, the central brain will know that someone is lifting the car. Depending on the situation, all of these alarm systems may cover the same ground. If someone is towing your car away, the mercury switches, the shock sensor and the radar sensor will both recognize that there is a problem. But different combinations of alarm triggers may indicate different events. Intelligent alarm system have brains that react differently depending on the combination of information they receive from these different sensors.