Design and Construction of a Simple Burglar Alarm System
Chapter One
AIM
The aim of this project is to design and construct a workable, reliable and effective burglar alarm system that is activated by light, break beam or pressure sensor.
OBJECTIVES
The following are the objectives of this project.
- To design a system that will detect an intruder breaking a beam into a confined place
- To design a system that will alert the user when a ray of light falls on the confined place
- To design a system that will detect an intruder when stepping on a foot sensor.
CHAPTER TWO
THEORETICAL BACKGROUND
This chapter takes a look at the theoretical use of the major components used for the implementation of the project. Each of these components is the key to the proper operation of the burglar alarm system.
TIMER
The 555 timer is an exceptionally useful accuracy IC that can act as either a timer or an oscillator. In timer mode, also known as monostable mode—the 555 basically acts as a “one-shot” timer; when a trigger voltage is applied to its trigger lead, the chip’s output goes from low to high for a period set by an external RC circuit. In oscillator mode—well know as astable mode—the 555 acts as a rectangular-wave generator whose output waveform (low duration, high duration, frequency, etc.) can be attuned by means of two external RC charge/discharge circuits.
The 555 timer IC is easy to use (requires few components and calculations) it is cheap and can be used in an astonishing number of applications. For example, with the aid of a 555, it is possible to generate digital clock waveform generators, LED and lamp flasher circuits, tone-generator circuits (sirens, metronomes, etc.), one-shot timer circuits, bounce-free switches, triangular-waveform generators, frequency dividers, etc. In this design, we configure 555 Timer in Monostable Mode[4].
How 555 Timer works in monostable mode.
IC 555 hooked up in the monostable configuration (one-shot mode). Unlike the astable mode, the monostable mode has only one stable state.
This means that for the output to switch states, a visibly applied signal is needed.
The monostable circuit only has one stable state. That is, the output rests at 0 V (in reality, more like 0.1 V) until a negative-going trigger pulse is applied to the trigger lead—pin 2. (The negative-going pulse can be implemented by momentarily grounding pin 2, say, by using a pushbutton switch attached from pin 2 to ground.) After the trigger pulse is applied, the output will go high (around VCC − 1.5 V) for the duration set by the R1C network. Without going through the derivations, the width of the high output pulse is t width = 1.10R1C. [2]
COMPARATOR
A comparator circuit compares two voltage signals and determines which one is greater. The result of comparison is indicated by the output voltage: if the op-amp’s output is saturated in the positive direction, the non- inverting input (+) is greater or more positive than the inverting input (-), all voltages are measured with respect to ground. If the op-amp’s voltage is near the negative supply voltage ( i.e 0 or ground potential), it implies the inverting input (-) has a greater voltage applied to it than the non-inverting input(+) .[6]
CHAPTER THREE
SYSTEM DESIGN
INTRODUCTION
An intruder blocks a projected infrared beam (in an opto-isolator) and generates a clock pulse, the same thing happens when a ray of light falls on the light dependent resistor. The opto-isolator is made up of an infrared transmitter and a photo-diode receiver.In view of all the varieties explored in the earlier preview section, we notice that many dissimilar types of alarm systems that can be used for household safety, there are some systems which are in place already and some still under examination to the world market. At the moment, many systems which are available on the market they contain features of electronic systems which are mostly in use to offer necessary safety for the home and those systems can be customized according to the necessary requirement. The system’s alarm will be triggered if;
- An intruder interrupt the opto-isolator
- A ray of light falls on the Light Dependent Resistor
- An intruder step on switch 1
THE POWER SUPPLY UNIT
The power supply stage provides the appropriate DC voltage requirements to ensure the circuit components (especially the Active components) are powered properly. The circuit uses +5VDC supply. The power supply stage is a linear power supply type and involves a step down transformer, Rectifier, Filter capacitor, and a voltage regulators, to give the regulated DC voltage.
The circuit for the power supply stage is shown in fig 10 below.
CHAPTER FOUR
TESTING AND CONSTRUCTION
INTRODUCTION
This chapter also discusses the hardware section of the project. It gives details of the pictures used during construction and some elaborate explanation of the devices used. This entails the construction and testing of the burglar alarm system.
CHAPTER FIVE
CONCLUSION AND RECOMMENDATIONS
The project which is the design and construction of a burglar alarm system was designed considering some factors such as application, design economy, availability of components and research materials, efficiency, compatibility and portability and also durability. The performance of the project after test met design specifications
A simple sound activated burglar alarm system has been designed, constructed and
tested. It is suitable for indoor security especially in small rooms jewelry stores and art galleries. This burglar alarm is thus very good for safe guarding valuables.
The construction was done in such a way that it makes maintenance and repairs an easy task and affordable for the user should there be any system breakdown.
LIMITATIONS
The project worked according to design specification but has the following limitations.
- The project has no means of alerting a security personnel far away from the device, the personnel has to be close by to hear the alarm and see the flashes to take necessary action.
- The project also does not include sound and motion detection sensors within it’s design.
RECOMMENDATIONS
Like every other work, this work is not without its limitations and can be improved upon. On this basis recommendations have been made for improvement.
A connection to a telephone dialer that can dial the security and relay a preprogrammed message with the address of the burglary scene can also be incorporated for better efficiency.
A transducer that detects movement and sound can be used can be used to increase the sensitivity and the overall effectiveness of the burglar alarm.
REFERENCES
- Jayashri Bangali and Arvind Shaligr, Design and Implementation of Security Systems for Smart Home based on GSM technology. 2013
- Mahmud Shehu AHMED, Abubakar Sadiq MOHAMMED, Genesis Abah AGBO,development of a Simple Sound Activated Burglar Alarm System.Published by Leonardo Journal of Sciences.2006
- Mae , Y,; SaaS , N .; Inonu ,K. ; Await.; “Person Detection by Mobile Manipulator for Monitoring”,SICE 2003 Annual Conference, pages-2801-2806.
- Paul Scherz. Practical electronics for inventors (page 273-274). Published by Mcgraw – Hild(2000).
- George Love Day, Essential Electronics (page 241- 244) Transistor , Published by Pitman (1984).
- www.allaboutcircuits.com
- Last Visit: 06/03/2016, 2:31pm
- www. Futureelectronics.com /en/diodes/bridge- rectifier . aspx. Last Visit: 10/22/2015,
