a simple control system

7/29/2019 A SIMPLE CONTROL SYSTEM

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A SIMPLE CONTROL SYSTEM

(A Burglar Alarm)BY

GEORGE REX AZUBUIKE

(ICT INSTRUCTOR)


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TABLE OF CONTENT

1. Introduction

2. Definition of the System

3. Structure of the System

4. How a Burglar Alarm Works4.1. Breaking the Circuit

5. Safety Measures and Precautions

4.2. Detecting Motion

4.3. Sounding the Alarm

5. Conclusions


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INTRODUCTION

A burglar alarm is one common control system that ismostly seen in modern homes today. This kind of

security system ranges from simple radar-based

motion detector to a complex passive infrared motion

detector. Most homes, offices and supermarkets aregreatly installed with the most sophisticated kind of

control system for safety purpose, (which of course is

one of the underlying fact about a control system).


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DEFINITION OF THE SYSTEM

A Burglar Alarm is:

A control system that has an inbuilt electronic

bell which sends loud warning signal such that

people from a mile away could hear it.

A mechanical/electrical system used to

scare off burglars if they breach theprotected area with a loud bell or siren.


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STRUCTURE OF THE SYSTEM

CLOSE DOORMagnet Closes

Switch

Relay Component

Powered On

Buzzer Stays

OpenFeedback

No Alarm

Closing The Door

OPEN DOORMagnet Opens

Switch

Relay Component

Powered Off

Buzzer ClosesAlarm TriggersFeedback

Opening the Door


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BREAKING THE CIRCUIT

The Magnetic Sensor

When the door is closed, the magnet pulls the metal switch closed. The current powersthe relay's electromagnet, so the ringbell (i.e buzzer) circuit stays open. When you movethe magnet by opening the door, the spring sends the switch back into the open position.This cuts off the current and closes the relay, sounding the alarm. For windows, if the

window is pushed open, the magnet slides out of line with the switch, and the buzzer isactivated.

Spring

BatteryTerm

inals


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BREAKING THE CIRCUIT (Contd)

The alarms in the system is basically the maincomponent, and it can be divided into two categories:

Closed-circuit system:

in a closed-circuit, the electric circuit is closed when the door is

shut. This means that as long as the door is closed, electricitycan flow from one end of the circuit to the other. But if somebodyopens the door, the circuit is opened, and electricity can't flow.This triggers an alarm.

In an open-circuit system, opening the door closes the circuit,

so electricity begins to flow. In this system, the alarm is

triggered when the circuit is completed.

Open-circuit system:

Note This: Closed circuits are normally a better choice than open circuitsbecause an intruder can deactivate the open circuit by simply cutting the

connected wires.


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BREAKING THE CIRCUIT (Contd)

Components of the System

A closed circuit consists of a few simple components. Forthe most basic design, a burglar alarm would have:

a battery to power the electric circuit

a spring-driven metal switch built into a door frame

a magnet embedded in the door, lined up with the switch

a separately-powered buzzer (doorbell: a signal button) with a relay-driven switch.

a control box.


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DETECTING MOTIONA motion detector detects an intruder who has in someway entered thehouse without the alarm sounding. It is just a step above a singletrigger. Below is a Motion detector:

There are 3 (three) types of motion detectors. They are:

1. Radar-based motion detector: This is an automatic door opener.

It is mostly seen in modern homes

2. Photo-sensor motion detector: This is a light sensored detector. It ismostly used in malls for detecting

entry into this place.

3. Passive infrared (PIR) motion detectors:These sensors sees theinfrared energy emitted by

an intruder's body heat. It is

the most advanced as

compared to the others


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SOUNDING THE ALARM

This is the final phase of the burglar alarm system. In this stage,thecontrol box will be connected to several componentssuch as; therelay, battery, buzzer (or doorbell) and a switch.

Connecting the control box to all these components will do thefollowing when the door is pushed:

a siren or other loud alarm noise

flashing outdoor lights

a telephone auto-dialer

The siren and lights serve three functions:

1. They alert occupants and neighbors that someone has broken into the house.

2. They drive the intruder away

3. They signal to police which house has been broken into


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SOUNDING THE ALARM (Contd)

The telephone auto-dialer can :

1. Dial the police directly, and play a pre-recorded message giving the address

of the house and any other relevant information. This message will usually

play over and over so that the police will still hear it even if the call is put on

hold for some time.

2. Dial the security company that installed the equipment. In this case, the

control box can feed specific information about the intrusion -- which circuits

or motion detectors were activated, etc. The security company then relays this

information to the police


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SAFETY MEASURES AND PRECAUTIONS

1. A Burglar Alarm is just a simple security control system, so for profficientfunction resort to a more advanced system, may be a passive infrared

detector motion.

2. Always leave the Burglar Alarm on even when you are going out.

Precautions

Safety Measures

1. Obviously, the importance of the burglar alarm was to alart property

owners on the presence of invaders and intruders

2. With this Sort of System put in place, certain intruders/invaders might

decide not to trespass for them not to get caught.. the propety is safe!


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CONCLUSION

With proper planning and implementation, a simple control system will

Definitely meet the requirement specification for the various design processWhich are:

Input

Process

Output


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a simple control system

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