Think Twice about Breaking into My Car

After recently having a friend’s car broken into, I decided it was time to research how I could go about setting up a car alarm.  I found out some interesting information and thought I’d share it with you.  First, a vehicle alarm is a device that can be installed in a car, to protect it from being stolen or from someone stealing my stuff that I have in it.  Vehicle alarms work by emitting a loud sound, the part I like the best, which is triggered by sensors, switches, and other devices which can pick up changes in a vehicle.

Alarms for vehicles, are also usually connected to the lighting system, and allows the lights to flash when the alarm is set off.  These indicators which are triggered by the alarm are supposed to get the attention of people who are in the general area of the vehicle and scare off the thief, being that lots of people will be looking out their windows to see what is going on.  Another feature available is a kill switch, another item I like, which will disengage the starter from being able to be operate it so the car cannot be hot-wired.  At this point if it was up to me, I would love to electrocute the person trying, but I haven’t found that kit yet.

The main component of a vehicle alarm kit is a device which gathers all the information from the sensors and switches, kind of like a computer, to determine whether to set off the alarm.  A vehicles alarm system is also usually kept on a backup battery to prevent it from being disabled if the main battery is disconnected, which sounds a little complex to do, but well worth the effort.  The main component of the alarm system and the back-up battery are normally hidden to prevent them from being tampered with or disabled. The alarm on a vehicle can be turned on or off using a button which is usually located on a key fob.

To understand alarm basics, I found that the simplest trigger that can be found on a vehicle alarm system is the door alarm, which uses a single switch to trigger the alarm.  This single switch is triggered to set off the alarm, and make plenty of noise, when the door is opened while the alarm system is set.  When an alarm is set, a complete unbroken circuit is created inside the vehicle.  If you hooked up your hood, trunk, or door, and someone tries to open it while the alarm is set, the switch will break the circuit and will set off the alarm.  This method of protection is highly effective but offers limited protection.  Having an alarm that is only set off when a door is opened won’t stop a thief from breaking a window to get in.

To stop that from happening, you need to detect when a window is being broken into.  This requires using a vehicle alarm feature with window and pressure sensors.  This device is a microphone that can hear when glass is being smashed.  Since broken glass has its own sound frequency, the alarm won’t be set off by other noises around the car which may resemble glass breaking.  Pressure sensors are also used in vehicle which can tell when a window has been broken or when a door is opened while the alarm is engaged.  Even if pressure inside the vehicle is the same as pressure outside, a sensor can pick up the added pressure of opening a door or wind blowing in from an open window.  Window and pressure sensors are among the best ways to detect when a window in a vehicle has been broken or tampered with.

Now, for a more advanced vehicle alarm system, you may need something like a shock sensor alarm.  This type of alarm will go off if the vehicle is moved, jolted, or gets hit, while the alarm is set and the vehicle is stationary.  The shock sensor works by using a simple metal rod which has two flexible metal contacts positioned just above one another that need to stay in alignment.  When the vehicle experiences a jolt with the alarm set, the metal contact may flex enough which can cause the rod and the contact to touch each other which will complete the circuit and set off the alarm.  While it’s nice that this really makes it hard for someone to move the vehicle, all too often alarms go off because things like high winds, earthquakes, or anything else which may vibrate the vehicle.  Even having a truck pass too closely by does it, causing the vehicle to have motion and sets off a false alarm, which I’m sure your neighbors won’t like.

Unfortunately I’ve been woken up too many times at night only to see nothing going on, but annoyed by someone’s car alarm that’s going off.  I just wish that people who have issues like that would lower the sensitivity a little so it’s not so easily set off.

Now for the worst case, which really bugs me, sometimes thieves won’t even bother trying to steal the car; they just want to take pieces of it, which just amazes me how someone can do this, since it’s not that quick to do.  I’ve heard friends who have had come outside in the morning to find their car on the ground missing all their wheels and tires.  Amazing!

Lastly, there are the ones who simple hook your car up to them using a tow truck and simple drag it away.  The most effective way to combat this is to have motion and tilt sensors in a vehicle.  These sensors typically use cylinders which are filled with mercury.  When the vehicle is moved, tilted, or pulled while the alarm is set, the mercury will all rush to one end of the cylinder which will set off the alarm.  Alarms which use this method typically use multiple cylinders which are positioned at different angles to prevent false alarms.


I hope all this information helps.  It’s a real battle to just protect your own property these days!