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Burglar alarms are systems designed to detect unauthorized entry into a building or area. They consist of an array of sensors, a control panel and alerting system, and interconnections. Sensors detect intruders by many methods such as monitoring door and window contacts, by passive infrared motion detectors, ultrasound, vibration, electric or magnetic fields, or microwaves. Sensors may be directly wired to a control panel that provides sensor power, or may communicate wirelessly.

Burglar alarms (or perimeter security systems, perimeter detection systems, Perimeter protection, intrusion detection systems and other terms for the same thing) are used in residential, industrial, and commercial properties for protection against theft or property damage. Mobile alarm systems protect vehicles and their contents (“car alarms”). Prisons and military facilities use intrusion detection systems for security and control of access. Burglar (or intrusion), alarms are systems designed to detect unauthorized entry into a building or area.

They consist of an array of sensors, a control panel and alerting system, and interconnections. Sensors detect intruders by many methods such as monitoring door and window contacts, by passive infrared motion detectors, ultrasound, vibration, electric or magnetic fields, or microwaves. Sensors may be directly wired to a control panel that provides sensor power, or may communicate wirelessly.

Basically, the burglar alarm is a device that monitors the designated area or areas to detect the presence of suspicious elements. The system takes the help of the sensor to detect such elements. Once found, the system sends emergency signals to the user or to the monitor station if the user so intends.

Some alarm systems serve a single purpose of burglar or fire protection. Combination systems provide both fire and intrusion protection. Intrusion alarm systems may also be combined with closed-circuit television surveillance systems to automatically record the activities of intruders, and may interface to access control systems for electrically locked doors. Systems range from small, self-contained noisemakers, to complicated, multi-zoned systems with color-coded computer monitor outputs.

Burglar alarm is used in residential, industrial, and commercial properties for protection against theft or property damage.


A Burglar Alarm is widely used to create a warning signal(siren that renders very loud noise), which makes it become very easy to scare off the burglars. Burglar Alarm System is a must for most of the houses or business as it provides first line of defence from the Burglars.

Statistics shows that individuals who have no burglar alarm system installed in their home or business tend to be burglarized more than those who have burglar alarm system.

Installing a capable alarm system will go a long way to decrease the chance of coming home to find that you have been burgled. If any intruder wants to enter the home through the door or window without permission, home owner would be instantly alerted by the burglar alarm.

The main purpose of the burglar alarm systems are to avoid break-ins, but other advanced models are built to keep your home safe from other threats. Compared to burglar alarms a few years back, home burglar alarm system nowadays are highly advanced and more sophisticated.

These gadgets are especially designed to protect your homes from any harm or threats. A burglar alarm system may be used for other than one purpose, such as detecting suspicious movement since they can also be used for multiple purposes as well. These include, fire, safety alarms, as well as intrusion. These can also be used simultaneously as well.


This burglar alarm system circuit is using a infrared proximity detector that triggers an alarm when the rays falling on its sensor are interrupted. It is different from others burglar alarm systems because is a very simple diy project and can offer you great satisfaction.


The operation of a burglar alarm is the same that of an electric circuit. This principle works in the same way with burglar alarms. The only difference is that the movements of an intruder will be detected by the switch. If an intruder breaks in a house through a door or window, his movements will be detected by a switch which will trigger the burglar alarm.

There are 2 categories of circuits:

  • closed-circuit system
  • open-circuit system

In a closed circuit system, when a door or window is shut, the electric circuit is closed. This means that electricity can flow from one end to another in the circuit. But when the door or window is opened by an intruder, the circuit will be open, thus the alarm will be triggered. This works opposite in an open-circuit system. The alarm will instead be triggered when the door or window is closed. The alarm will sound once the circuit is closed.

In knowing about burglar alarms and how they work, one should recognize the magnetic sensor and know how it works. The magnetic sensor is composed of:
1. A battery that is powering the circuit
2. A spring-driven switch made of metal that is built onto a door or window frame
3. A magnet that is embedded in the door or window, also lined up with the switch
4. A buzzer that is powered separately with a relay-driven switch

When magnetic sensor will detect the movements in the door or window, it would send signals to the control box which would in turn send a signal to the alarm device, such as a bell. The bell will sound the alarm, which will frighten the intruder or make him go away. The control box also can send a signal to the police department so that they can come and apprehend the intruder. This is located in a safe place so that the intruder cannot find and disengage it.


Sensor types

a) Indoor

These types of sensors are designed for indoor use. Outdoor use would not be advised due to false alarm vulnerability and weather durability
b) Outdoor

These types of sensors would be found most of the time mounted on fences or installed on the perimeter of the protected area.

a) Indoor

i. Passive infrared detectors

The passive infrared detector (PIR) is one of the most common detectors found in household and small business environments because it offers affordable and reliable functionality. The term passive means the detector is able to function without the need to generate and radiate its own energy (unlike ultrasonic and microwave volumetric intrusion detectors that are “active” in operation).

PIRs are able to distinguish if an infrared emitting object is present by first learning the ambient temperature of the monitored space and then detecting a change in the temperature caused by the presence of an object. Using the principle of differentiation, which is a check of presence or nonpresence, PIRs verify if an intruder or object is actually there. Creating individual zones of detection where each zone comprises one or more layers can achieve differentiation. Between the zones there are areas of no sensitivity (dead zones) that are used by the sensor for comparison.

ii. Ultrasonic detectors

Using frequencies between 15 kHz and 75 kHz, these active detectors transmit ultrasonic sound waves that are inaudible to humans. The Doppler shift principle is the underlying method of operation, in which a change in frequency is detected due to object motion.
This is caused when a moving object changes the frequency of sound waves around it.

Two conditions must occur to successfully detect a Doppler shift event:

• There must be motion of an object either towards or away from the receiver.
• The motion of the object must cause a change in the ultrasonic frequency to the receiver relative to the transmitting frequency.

The ultrasonic detector operates by the transmitter emitting an ultrasonic signal into the area to be protected. The sound waves are reflected by solid objects (such as the surrounding floor, walls and ceiling) and then detected by the receiver. Because ultrasonic waves are transmitted through air, then hard-surfaced objects tend to reflect most of the ultrasonic energy, while soft surfaces tend to absorb most energy.

When the surfaces are stationary, the frequency of the waves detected by the receiver will be equal to the transmitted frequency. However, a change in frequency will occur as a result of the Doppler principle, when a person or object is moving towards or away from the detector. Such an event initiates an alarm signal. This technology is considered obsolete by many alarm professionals, and is not actively installed

iv. Microwave detectors

This device emits microwaves from a transmitter and detects any reflected microwaves or reduction in beam intensity using a receiver. The transmitter and receiver are usually combined inside a single housing (monostatic) for indoor applications, and separate housings (bistatic) for outdoor applications. To reduce false alarms this type of detector is usually combined with a passive infrared detector or “Dualtec” alarm.

Microwave detectors respond to a Doppler shift in the frequency of the reflected energy, by a phase shift, or by a sudden reduction of the level of received energy. Any of these effects may indicate motion of an intruder.

v. Glass break detectors

The glass break detector may be used for internal perimeter building protection. When glass breaks it generates sound in a wide band of frequencies. These can range from infrasonic, which is below 20 hertz (Hz) and can not be heard by the human ear, through the audio band from 20 Hz to 20 kHz which humans can hear, right up to ultrasonic, which is above 20 kHz and again cannot be heard. Glass break acoustic detectors are mounted in close proximity to the glass panes and listen for sound frequencies associated with glass breaking.

Seismic glass break detectors are different in that they are installed on the glass pane. When glass breaks it produces specific shock frequencies which travel through the glass and often through the window frame and the surrounding walls and ceiling. Typically, the most intense frequencies generated are between 3 and 5 kHz, depending on the type of glass and the presence of a plastic interlayer. Seismic glass break detectors “feel” these shock frequencies and in turn generate an alarm condition.

The more primitive detection method involves gluing a thin strip of conducting foil on the inside of the glass and putting low-power electrical current through it. Breaking the glass is practically guaranteed to tear the foil and break the circuit.

vi. Smoke, heat, and carbon monoxide detectors

Most systems may also be equipped with smoke, heat, and/or carbon monoxide detectors. These are also known as 24 hour zones (which are on at all times). Smoke detectors and heat detectors protect from the risk of fire and carbon monoxide detectors protect from the risk of carbon monoxide. Although an intruder alarm panel may also have these detectors connected, it may not meet all the local fire code requirements of a fire alarm system.

b) Outdoor

i. inertia sensors

These devices are mounted on barriers and are used primarily to detect an attack on the structure itself. The technology relies on an unstable mechanical configuration that forms part of the electrical circuit. When movement or vibration occurs, the unstable portion of the circuit moves and breaks the current flow, which produces an alarm. The technology of the devices varies and can be sensitive to different levels of vibration. The medium transmitting the vibration must be correctly selected for the specific sensor as they are best suited to different types of structures and configurations.

A rather new and unproven type of sensors use piezo-electric components rather than mechanical circuits, which can be tuned to be extremely sensitive to vibration.

• pros: Very reliable sensors, low false alarm rate and middle place in the price range.
• cons: Must be fence mounted. The rather high price deters many customers, but its effectiveness offsets its high price. Piezo-electric sensors are a new technology with an unproven record as opposed to the mechanical sensor which in some cases has a field record in excess of 20 years.

ii. Passive magnetic field detection

This buried security system is based on the Magnetic Anomaly Detection principle of operation. The system uses an electromagnetic field generator powered by two wires running in parallel. Both wires run along the perimeter and are usually installed about 5 inches apart on top of a wall or about 12″/30 cm below ground. The wires are connected to a signal processor which analyzes any change in the magnetic field.

This kind of buried security system sensor cable could be embedded in the top of almost any kind of wall to provide a regular wall detection ability, or can be buried in the ground. They provide a very low false alarm rate, and have a very high chance of detecting real burglars. However, they cannot be installed near high voltage lines, or radar transmitters.

iii. E-field

This proximity system can be installed on building perimeters, fences, and walls. It also has the ability to be installed free standing on dedicated poles. The system uses an electromagnetic field generator powering one wire, with another sensing wire running parallel to it. Both wires run along the perimeter and are usually installed about 800 millimeter’s apart. The sensing wire is connected to a signal processor that analyses:

• amplitude change (mass of intruder),
• rate change (movement of intruder),
• preset disturbance time (time the intruder is in the pattern).

These items define the characteristics of an intruder and when all three are detected simultaneously, an alarm signal is generated. The barrier can provide protection from the ground to about 4 metres of altitude. It is usually configured in zones of about 200 metre lengths depending on the number of sensor wires installed.

• pros: concealed as a buried form.
• cons: expensive, short zones which mean more electronics (more money), high rate of false alarms as it cannot distinguish a cat from a human. In reality it does not work that well, as extreme weather causes false alarms.

iv. Microwave barriers

The operation of a microwave barrier is very simple. This type of device produces an electromagnetic beam using high frequency waves that pass from the transmitter to the  receiver, creating an invisible but sensitive wall of protection. When the receiver detects a difference of condition within the beam (and hence a possible intrusion), the system begins a detailed analysis of the situation. If the system considers the signal a real intrusion, it provides an alarm signal that can be treated in analog or digital form.

• pros: low cost, easy to install, invisible perimeter barrier, unknown perimeter limits to the intruder.
• cons: extremely sensitive to weather as rain, snow and fog for example would cause the sensors to stop working, need sterile perimeter line because trees, bushes or anything that blocks the beam would cause false alarm or lack of detection.

v. Microphonic systems

Microphonic based systems vary in design but each is generally based on the detection of an intruder attempting to cut or climb over a chain wire fence. Usually the microphonic detection systems are installed as sensor cables attached to rigid chain wire fences, however some specialized versions of these systems can also be installed as buried systems underground. Depending on the version selected, it can be sensitive to different levels of noise or vibration. The system is based on coaxial or electro-magnetic sensor cable with the controller having the ability to differentiate between signals from the cable or chain wire being cut, an intruder climbing the fence, or bad weather conditions.

The systems are designed to detect and analyses incoming electronic signals received from the sensor cable, and then to generate alarms from signals which exceed preset conditions. The systems have adjustable electronics to permit installers to change the sensitivity of the alarm detectors to the suit specific environmental conditions. The tuning of the system is usually accomplished during commissioning of the detection devices.

• pros: very cheap, very simple configuration, easy to install.
• cons: some systems have a high rate of false alarms because some of these sensors might be too sensitive. Although systems using DSP (Digital Signal Processing) will largely eliminate false alarms on some cases.

vi. Taut wire fence systems

A taut wire perimeter security system is basically an independent screen of tensioned tripwires usually mounted on a fence or wall. Alternatively, the screen can be made so thick that there is no need for a supporting chain wire fence. These systems are designed to detect any physical attempt to penetrate the barrier. Taut wire systems can operate with a variety of switches or detectors that sense movement at each end of the tensioned wires.

These switches or detectors can be a simple mechanical contact, static force transducer or an electronic strain gauge. Unwanted alarms caused by animals and birds can be avoided by adjusting the sensors to ignore objects that exert small amounts of pressure on the wires. This type of system is vulnerable to intruders digging under the fence. A concrete footing directly below the fence is installed to prevent this type of attack.

• pros: low rate of false alarms, very reliable sensors and high rate of detection.
• cons: Very expensive, complicated to install and old technology.

vii. Fibre optic cable

A fibre-optic cable can be used to detect intruders by measuring the difference in the amount of light sent through the fibre core. If the cable is disturbed, light will ‘leak’ out and the receiver unit will detect a difference in the amount of light received. The cable can be attached directly to a chain wire fence or bonded into a barbed steel tape that is used to protect the tops of walls and fences. This type of barbed tape provides a good physical deterrent as well as giving an immediate alarm if the tape is cut or severely distorted. Other types work on the detection of change in polarization which is caused by fiber position change.

• pros: very similar to the Microphonic system, very simple configuration, easy to install.
• cons: high rate of false alarm or no alarms at all for systems using light that leaks out of the optical fiber. The polarization changing system is much more sensitive but false alarms depend on the alarm processing.

viii. H-field

This system employs an electro-magnetic field disturbance principle based on two unshielded (or ‘leaky’) coaxial cables buried about 10–15 cm deep and located at about 1 meter apart. The transmitter emits continuous Radio Frequency (RF) energy along one cable and the energy is received by the other cable. When the change in field strength weakens due to the presence of an object and reaches a pre-set lower threshold, an alarm condition is generated. The system is unobtrusive when it has been installed correctly, however care must be taken to ensure the surrounding soil offers good drainage in order to reduce nuisance alarms.

• pros: concealed as a buried form.
• cons: can be affected by RF noise, high rate of false alarms, hard to install.


Installation System Of Alarm

Because all switches in this closed-circuit system are in a wiring loop, opening any one of them breaks the loop and triggers the bell-ringing circuit.

Some home security systems are complex and should be installed by a professional. However, there are many good home security systems sold in kit forms that can be installed by any do-it yourselfer. Most simple systems use a bell, loud buzzer, or other sound source to note intrusion.

Installation involves mounting the sound source or sounder in a location where it can be easily heard. Then attach a circuit of switches to the sounder and connect a battery to the system. Since the sounder operates from the battery, it remains an effective alarm system even in the event of a power failure. Alternately, battery-operated remote wireless sensors and controls can be installed. However, make sure that batteries are replaced regularly.

In electrical terminology, this alarm system is called a closed-circuit system. When the doors and windows are shut, the attached switches are closed. Because all the switches are in a wiring loop, opening any one of them breaks the loop and triggers the sounder circuit. Simply closing the door or window, moreover, does not restore the switch loop circuit continuity and does not stop the sound until either the battery becomes exhausted or someone switches off the circuit from battery to sounder.

There is an electronic switch built into the sounder. This switch is turned on by breaking the magnetic-switch loop. A key-operated switch in the sounder circuit allows you to turn the alarm system completely off when it is not needed. Also, once the alarm goes on, operating the key switch is the only way to silence the sounder. Only someone who has a key to the switch can reset the system.

The switch device consists of two parts that look much alike: one small plastic box that contains a strong magnet, and another that contains the actual switch. When magnet and switch are not near each other, the switch contacts are separated and the switch is open. On the other hand, when the magnet and switch are near each other, the switch contacts move together and the switch closes. The magnet part of the device is screwed to a door or window, and the switch part is screwed to the door or window frame. Thus, opening a door or window separates magnet from switch, causing the switch to open and trigger the alarm.


Burglar alarms are one of the most significant ways to deter the intruders from home. These alarms work even in the absence of the homeowners and thus enhance the security of the house.
However, the alarm systems generally use intricate sensors and other sophisticated devices that need regular maintenance. Therefore, these alarms should be maintained properly to get optimum performance from them.

Components of Burglar Alarms

The entire burglar alarm system comprises of several parts.
» Control panel
» Keyboard
» Sensors
» Motion detectors
» Siren
» Flash light

Why regular maintenance of burglar alarm is important?

Burglar alarms have several components that collaborate with each other to provide the optimum security solution. However, as they work together, it becomes very important to monitor their activities at regular interval. Otherwise, the alarm may either sound falsely or may not set off at all.

In both these occasions, the homeowners will find themselves in great trouble. Since the use of the home alarm system is necessary in emergency, homeowners often don’t have the time or scope to repair them and start operating them. So, it is important that professional people inspect the alarm systems to find faults.

Maintenance Of Burglar Alarm

Some maintenance tips

Though the complicated issues of the burglar alarm system must be fixed by professional service providers, there are some basic steps that the users of these alarms can take to enhance the functionality.

i. The homeowners should have a look at the entire system for visible signs and damages. If they can detect anything, they should contact the service providers.

ii. Some of the security system requires power from batteries. While using such system, the users should replace the batteries at regular interval.

iii. The users must clean the system regularly. Here, cleaning only refers to the standard wiping that the users can perform.

iv. Users must follow the instructions printed in the manuals. They are meant to optimize the performance of the alarm system. So, if a user does not follow them, there is a chance of damaging the system.

v. Finally, users must keep a close eye at the way the entire system is working. If there is even a slight discrepancy, it will be wise not to overlook it. The service providers should contact the customer cares immediately to solve the problem


ADT burglar alarm system has become pop in every house non only of its services but also helps its customers to enjoy other benefits. These alarms can be used in unlike places and can also be used in an individual’s vehicle to stop theft and prevent his car from being robbed.

The alarm systems can be concealed in the car or a vehicle which comes to life when it is tampered by some one and thus alerts the car proprietor from taking an immediate action. The device makes a tremendous noise when a alien comes in contact with it; the noise is controlled by the vehicle owner by using a remote control keychain. The ADT alarm systems ar really effective against a break-in by an unknown unknown and one can really count on it during a loot or robbery at one’s house.

Apart from making a siren, the burglar systems are also used to lock the doors of the car and prevent the car from being used. The car burglar system not only makes noise but also prevents valuable assets which could be inside the car from being robbed. No doubt that these system is camouflage and can be installed where ever you need them.

There are also some alarms which consists advanced technology which gives immediate response to the cops. These alarm systems non only makes a noise during an illegal operation but also sends a signal to the cops warning them about a break-in or providing information about a stolen vehicle. The signals that are sending by the alarm system ar standard by the monitoring centers and thus inform the cops to take immediate action against burglar.


The ADT burglar alarm system comes within your budget, though other systems ar easy gettable in the market and offers you a small amount to be paid; they are unreliable and would confuse you while sending an immediate response. They would provide you the last form of self-protection. ADT burglar alarm system gets you the best home security system within your budget.

Equipment’s Included:

The burglar system includes devices such as fire detectors, motion detectors, doors and windows sensors and control keypad. These gadgets or the devices can be placed according to the places or could be mounted where it would be out of reach.


The burglar systems are operated without using any cables or chords which mean the subscriber can sacrifice those wires which take him hours for installation. They can be fixed by using two to three screws and would save your precious time during the installation.

Customer Care Services:

ADT home services provide is clients with 24/7 client care services where our experts will be present to solve your problems regarding the installation of your home security system.


There are some companies which provide its customers with certain home security systems which come with a guarantee code. The client must take a good look on the product to find the guarantee code.


The list of services to be monitored at a Central Station has expanded over the past few years to include: Access Control; CCTV Monitoring; Environmental Monitoring; Intrusion Alarm Monitoring; Fire Alarm & Sprinkler Monitoring; Critical Condition Monitoring; Medical Response Monitoring; Elevator Telephone Monitoring; Hold-Up or Panic Alarm Monitoring; Duress Monitoring; Auto Dialer tests; Open & Close Signal Supervision & Reporting; Exception Reports; and PIN or Passcode Management. Increasingly, the Central Stations are making this
information available directly to end users via the internet and a secure log-on to view and create custom reports on these events themselves.

To be useful, an intrusion alarm system is deactivated or reconfigured when authorized personnel are present. Authorization may be indicated in any number of ways, often with keys or codes used at the control panel or a remote panel near an entry. High-security alarms may require multiple codes, or a fingerprint, badge, hand-geometry, retinal scan, encrypted response generator, and other means that are deemed sufficiently secure for the purpose.

Failed authorizations should result in an alarm or at least a timed lockout to prevent “experimenting” with possible codes. Some systems can be configured to permit deactivation of individual sensors or groups. Others can also be programmed to bypass or ignore individual sensors (once or multiple times) and leave the remainder of the system armed. This feature is useful for permitting a single door to be opened and closed before the alarm is armed, or to permit a person to leave, but not return.

High-end systems allow multiple access codes, and may even permit them to be used only once, or on particular days, or only in combination with other users’ codes (i.e., escorted). In any case, a remote monitoring center should arrange an oral code to be provided by an authorized person in case of false alarms, so the monitoring center can be assured that a further alarm response is unnecessary. As with access codes, there can also be a hierarchy of oral codes, say, for furnace repairperson to enter the kitchen and basement sensor areas but not the silver

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