One of the first and most reliable home security systems is the driveway alarms. They will let you know when those expected guest have arrived. They will also alert the neighborhood when unwanted visitors are there.
This type of security system only warns if there is an intruder in the driveway, which is good if you have a teenage daughter. This is also a good system to help you in at night. Since the trigger mechanism is already in place, a light can be hooked up to illuminate the area when the trigger is set off.
There are several different types of trigger mechanisms that can be used to set off the driveway alarms, each with a specific purpose or type of intruder being identified. There is the cable style that is reminiscent of the bell dinging at the gas station when a customer arrives. If the vehicle is light like a motorcycle or bicycle, no vehicle will be detected and no alarm sounded. These are unsightly since most are black cables that run across the driveway and are ½ "in diameter. The worst thing is if you have an annoying child near your home. They can jump on the cable just to set the alarm off.
For those that only want to be warned when a metal vehicle arrives like a delivery van, car or truck, metal detector can be set up on the sides of the driveway. These have a better appearance since they look like an inground sprinkler when activated, very small an unintrusive in appearance.
The most commonly used driveway alarms are the one that utilize a beam for detection. The most common beam is the infra red beam. The principal is simple, when the beam is broken, the alarm goes off. Once again the home owner will be vulnerable to that annoying child playing tricks that could set off the driveway alarms.
