Glass breaking sensor: circuit, principle of operation, installation

The security alarm system consists of sensors that directly monitor the guard zone, and then transmit the signal to the console. The latter already processes the data with the help of microprocessors and gives the command to actions. It can be a sound siren or automatic dialing in the security service. Elements are grouped by zone and control only their specific area. The motion and glass breakage sensor can be a single device and at the same time monitor sound and temperature changes. It is tuned to a sudden temperature fluctuation, and not to a gradual, so false alarms are excluded.

Depending on the events that can trigger an alarm, detectors are distinguished by the following types:

• Movement;
• discoveries;
• Glass breaking sensor;
• Vibration;
• To touch or approach;
• Alarm buttons.

All sensors can be combined or combined. The detectors can also be separated by signal transmission. They can be wireless and wired. The first still bear the name of radio channel. In wired power supply is carried out on a two-wire loop, or 4-wire detectors are provided with a power line from the unit. There is also a system in which the contacts open in the microswitch, after which an alarm is given.

Kinds

The glass break detector is used on the objects to detect damage and unauthorized access. In this case, the system transmits an alarm signal, or emits a sound. Types of such sensors depend on the principle of their action.

They can detect the following changes:

• Violation of the integrity of glass by mechanical action. For this purpose, electric contact detectors are intended.
• Oscillations of the glass surface under mechanical action. These sensors are piezoelectric or shock-contact.
• The vibrations of sound waves at the frequency of the sound of breaking. This is an acoustic glass break detector.

Electrocontact

Such a detector is attached directly to the glass and can look like a small wire or a piece of metal foil. A current is suitable for this device. Triggering of the sensor is due to the violation of the electrical circuit design, if the integrity of the conductive element is damaged.

With the development of more progressive detectors, this type is rarely used. This is due to the fact that such an element on glass is immediately evident, it is impossible to decorate it, and the costs of production and installation are very high. The scheme of the glass breakage sensor is given later in the article.

Acoustic

Such detectors are triggered when their sensing element reacts to sound waves whose frequency is similar to the sound of glass breaking. It is laid in the factory. Such devices have a strong sensitivity and the ability to accurately capture the spectrum of certain sounds. The advantage of this type is that it is a wireless glass break sensor.

To date, this is one of the most popular security elements. All due to the fact that they are easily and quickly mounted. You can do this indoors on any vertical surface or ceiling.

Piezoelectric

A glass break detector of this type catches the vibrations that occur when the window integrity is lost. The piezoelectric elements inside the device capture the smallest mechanical vibrations coming from the transparent glass and convert them into an electrical signal. Such a sensor, like an electrocontact, is located directly on the surface. This does not allow to use it on large objects or buildings, where non-standard architecture.

Functions

The main function of the glass breaking sensor is to give it a sound signal when the surface of the protected object is broken. In this case, the device has a number of programs that allow you to avoid triggering false alarms inside the room. Allow it to implement special additions:

• A device for monitoring the unauthorized opening of the sensor casing;
• Modes of testing;
• Sensitivity adjustment.

Detector Selection

The purchase of the sensor confuses not only its characteristics and functions, but also the manufacturer. Produce similar elements of security alarm in many countries, so the market abounds not only domestic, but also foreign samples. The difference can be seen only with in-depth consideration. For example, some foreign manufacturers may not take into account when designing such windows that were installed in Soviet times.

They have a number of characteristics:

• A wooden frame may deform with time, which will transmit waves from broken glass not as from a modern plastic double-glazed window;
• The wooden window has a small pane, which also affects the acoustic data;
• Typical designs have a certain thickness of glass;
• The installation of glass in the opening was carried out with the help of glazing beads, the cracks were sealed with putty, which eventually loses its plasticity and distorts the sound when broken;
• Glass, which has served more than 10 years, has in its structure scratches and various irregularities, which are caused by natural phenomena.

According to the functions and characteristics of modern domestic sensors are not inferior to foreign analogues. In any case, during production, some factors, such as room acoustics, could be simplified. The cost and installation of foreign detectors is in some cases much more expensive.

Installation

The installation of a glass break detector of different types has its differences, but important requirements remain. The main one is the right choice of installation site.

• The detector must be in the visibility zone of the protected glass, and its microphone must be directed directly to the object.
• The distance to the object should not be more than 3.6 meters. Even if the test shows that the system is working at a greater distance, there is no guarantee that the device will catch the sound well when the room acoustics change.
• Curtains on the window can interfere with the correct operation of the element. Therefore, it is desirable to install it behind curtains and at close range.
• The distance to the floor should be not less than 1.8 meters.
• Do not install the detector on the same wall as the protected object.
• The sensor will not work efficiently in places with a high noise level.
• Periodically, the element should be checked for operability, creating false noises.

Detector check

Verify that the device is located correctly, will help preliminary check. Glass breakdown sensors, whose operation principle is based on noise sensitivity of a certain frequency, is checked with a special tester. The operation is considered passed if three times the device responds to the tester. If not, you should change its location or remove the interfering objects (curtains, curtains).

When it is required to protect several windows, the tester should be located at the far end of the glass from the detector. At high or, conversely, insufficient sensitivity of the element, it can be adjusted.

So, we found out what the glass breakage sensors work. Now the choice is yours!