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‘Bells Only’ System (Type ‘B’ Alarm Systems)


This is the most popular type of system available and ranges from the very simple to the extremely
sophisticated. This type of system is not designed to call the police automatically – it sounds a bell or siren to attract attention and deter the potential burglar. However, a 'Speech Dialler' can be fitted to the system to contact you or your friends and neighbours if the alarm should activate.


‘Police Call’ System (Type ‘A’ Alarm Systems)


Otherwise known as a Remote Signalling system. Upon activation, the alarm system will send a ‘digitally coded signal’ to an Alarm Receiving Centre (ARC). The ARC will pass the alarm call to the police after taking steps to ascertain if the call is false.


Most systems are now operated by presenting a 'Fob' to the keypad rather than having to enter a PIN number into a keypad.


The control unit is the ‘brains’ of the alarm system and is usually situated in a cupboard, or under the stairs for a domestic system. The operating keypad is then installed in a convenient location, for example inside the front door. The control unit works from the mains supply with a rechargeable standby battery. It processes signals from the various detectors and sensors – and operates the sounders accordingly.



For reasons of identification and convenience, the protected premises are split into zones, which are individually managed by the control unit. Only one detector is fitted to each zone. This enables part of the system only, to be set, e.g. at night the downstairs can be armed whilst upstairs is ‘off’.

Movement Detectors

There are many types of movement detector available, which are generally used to protect a room. PIR’s (Passive Infra-Reds) are the most commonly installed ‘movement’ detector. Designed to be mounted in a corner or flat to the wall near the ceiling, a PIR detector ‘looks’ at the room and monitors the amount of infrared energy present.

Any rapid change in infrared energy, such as that caused by a moving person, will activate the alarm. There are also microwave, ultrasonic and – a combination of all of these – dual technology movement detectors available. There are even ‘Pet Friendly’ detectors available, which can differentiate between humans and cats and dogs!


Magnetic Contact Sensors

These sensors are used where detecting the opening of a window or door is required. A magnetic sensor comes in two parts - a magnet and a contact – both of which are usually encased in plastic. There are two basic types – the FLUSH type, designed to be unobtrusively sunk into a wooden door or window frame, and the SURFACE type, intended for use where sinking the sensor would be inappropriate, for example metal and UPVC doors and windows.
Vibration and Acoustic Detectors

These can be fitted on walls, windows or doors to detect physical vibrations. Acoustic detectors use similar technology in detecting airborne vibrations such as those made by breaking glass.

Personal Attack Button

Deliberately operated by a push button and reset via a key, this device is used to activate the alarm at any time, in the event of a personal emergency, whether the control unit is switched on or off. If your system is 'Remotely Monitored' operation of this button will cause a seperate 'Personal Attack'
alarm to be transmitted to the Alarm Receiving Centre for urgent police response.


Also available is a wireless personal attack button which can be connected to the alarm. This allows freedom to move anywhere around the property and grounds – but still provides protection. Particularly useful if carried in your car, for you arrive home in the dark hours.


Internal Sounder

The internal sounder will provide a very loud audible warning inside the premises. This is particularly important when the outside warning device may be difficult to hear by your neighbours or even by you (and the burglar!) in the house. It also prevents a burglar from hearing what is going on outside, making him even more vulnerable


External Sounder

The outside sounder will provide mechanical and weather protection for the warning sounder located inside the box, an electronic sounder is the most common. The bell box will be protected against unauthorised tampering or attack. Noise pollution legislation requires that external sounders do not
operate for more than 20 minutes. The box also has two small flashing LED lights within the box that can be seen at night as an additional deterrent and show that the box is 'Live'.

Remember that your highly visible alarm bell box will provide a deterrent to intruders and if your house or property is vulnerable to attack from the rear, it may be worth fitting a dummy bell box at the back. The bell box should be sited as high as possible. The bell box has its own battery back-up. It also contains electronics that takes care of powering the sounder and the length of time it will operate. This also ensures that the bell will continue to sound even if the unit is removed from the wall.

Strobe Flasher

Fitted within the external sounder, a strobe light will give visual warning that the alarm has activated, which is useful for identification within a row of alarm box-bearing buildings. The strobe will continue to flash even after the sounder has cut out.

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© Wilton Security Systems Ltd 2018