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Design And Construction A Police Siren Using 555 Timers

Electrical Electronics Engineering | Industrial Physics | Physics

Designing and constructing a police siren using 555 timers involves utilizing the versatile functionality of the 555 timer IC to generate the required audio signals. To start, configure the 555 timer in astable mode to produce a square wave with a frequency that alternates between two distinct values to mimic the characteristic wail of a police siren. Adjust the resistor and capacitor values in the timing circuit to control the frequency and duty cycle of the output waveform. Additionally, employ a second 555 timer configured as a voltage-controlled oscillator (VCO) to modulate the output frequency of the first timer, creating the rising and falling pitch effect typical of a siren. Utilize potentiometers or variable resistors to adjust the modulation rate and depth according to desired specifications. Connect suitable audio transducers or speakers to amplify and project the generated siren sound effectively. Ensure proper power supply and circuit protection measures are implemented for reliable operation. Testing and fine-tuning may be necessary to achieve the desired siren effect and ensure optimal performance.

A police siren is a loud electronics device that produces sound similar to police siren. Siren is used to get other road users or drivers on the road out of their way. This project is on police siren sound that sound effects like the siren of an ambulance or police car which features low-pitched tones alternately. This project will be comprised of the oscillator circuits of two set. Using IC-555 timer IC are main both unit. The first oscillator serve determine time period in changing a high-low sound tone, provide the proper frequencies about 0.5-1 Hertz. Then, second oscillator set the siren sound, before out to a speaker.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

INTRODUCTION
BACKGROUND OF THE PROJECT
PROBLEM STATEMENT
OBJECTIVE OF THE STUDY
PURPOSE OF THE PROJECT
SIGNIFICANCE OF THE PROJECT
THE EFFECTS OF POLICE SIRENS
SCOPE OF THE PROJECT
APPLICATION OF THE PROJECT
METHODOLOGY
PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

OVERVIEW OF THE PROJECT
ASTABLE MULTIVIBRATOR USING 555 TIMER
DESCRIPTION OF 555 TIMER IC
HISTORICAL BACKGROUND OF 555 TIMERS

CHAPTER THREE

3.0 METHODOLOGY

SYSTEM BLOCK DIAGRAM
SYSTEM DESCRIPTION
SYSTEM SCHEMATIC DIAGRAM
SYSTEM OPERATION
PARTS LIST
DESCRIPTION OF MAJOR COMPONENTS USED

CHAPTER FOUR

4.0 TEST AND RESULT ANALYSIS

CONSTRUCTION PROCEDURE AND TESTING ANALYSIS
CASING AND PACKAGING
ASSEMBLING OF SECTIONS
TESTING OF SYSTEM OPERATION
INSTALLATION OF THE COMPLETED DESIGN
COST ANALYSIS

CHAPTER FIVE

CONCLUSION
RECOMMENDATION
REFERENCES

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE PROJECT

Nowadays, there are a lot of emergency lights systems being used all over the world, and we cannot discuss all in this work. Siren has been around for a while and, although the most common type today is the so-called lightbar, there was a time when the whole system was a lot simpler. In 1940, security departments used just a single beacon to attract everyone’s attention and let them know that an official vehicle is approaching. Just like it happens today, when the siren was turned on, the other drivers (if any, given the traffic values at that time) were requested to clear the road and thus allow the security to pass safely.

Using this kind of technology had multiple advantages and the ace up its sleeve was definitely the cost. Purchasing a single beacon was of course a lot more affordable than investing in more complex solutions. Plus, since cars weren’t quite that fast at that time, the air resistance such a beacon had to face was pretty low, which means it could serve its purpose very well.

But time passed by and law enforcement agencies looked for more advanced and, extremely importantly, more efficient technologies. The single beacon we were talking about turned into a magnetic-mount system that allowed on-the-go use and which, in its turn, got replaced by full-sized light bars with multiple sound.

What you’re seeing today is what could be called the modern light bar which is, in essence, a contemporary interpretation of the traditional light bar introduced in early 1990s. Obviously, the siren sound may vary by country and the law enforcement organization that owns the vehicles.

1.2 PROBLEM STATEMENT

When police is in state of emergency can be traffic jammed and sometimes can also cause accident to motorist if their approach is not made known to the motorist and pedestrians. Police vehicles use a siren together with police lights for the purpose of warning motorists of their approach. Motorists are always expected to give priority to police vehicles that are responding to an emergency and can be recognized by the sound of a siren.

Police vehicles use a siren with the main goal of signaling their approach. This gives drivers more than enough time to react appropriately as this is essential due to the high speed associated with police cars responding to an emergency. The siren needs to be loud and clear, and there are specific sirens used for use only on police vehicles. This identifies sound as an approaching police car and cannot be confused with a siren used for any other reason.

1.3 OBJECTIVE OF THE PROJECT

The objective of this study is to design an electronic device that produces siren sound. This device was built around 555 timer integrated circuits. The 555 timer IC is an integrated circuit (chip) used for pulse generation, and oscillator applications. This device has the ability to produce different siren sounds when the potentiometer of the circuit is tuned.

1.4 SIGNIFICANCS OF THE PROJECT

Police sirens are a necessity when officers are called to respond to a crime, clearing road traffic to allow a quicker response, the sirens serve as a calling card to the criminal and the victim that the police are on the way. Sirens are to alert people that an emergency vehicle is approaching so that they can get out of its way. As such, the sirens are designed to catch drivers and pedestrians attention.

1.5 PURPOSE OF THE PROJECT

The purpose of this work is to design an outdoor siren sound generating system which is used to alert persons outside of potential danger. The sirens are sounded whenever a warning is issued. They may also be activated for other situations which require citizens to take shelter and seek more information from media outlets.

1.6 THE EFFECTS OF POLICE SIRENS

Aside from clearing road traffic to allow a quicker response Sirens have ulterior effects, from societal to health issues.

Loss of Hearing

The average person has 30,000 hair cells the transmit sound waves into nerve impulses. Loud noise destroys them, thus affecting your hearing. Long term or close, sudden exposure to the average siren, at 123 decibels, can affect hearing and even cause hearing loss.

Increased Blood Pressure and Heart Rate

The World Health Organization said in 2008 that sudden noise from police sirens not only increases noise pollution, but also impacts a person’s health, raising their heart rate and blood pressure and posing a serious health issue.

Bad Neighborhood

The constant sound of sirens can negatively affect an entire community, adding to a perception that the community is a “high crime” area or one where there is “increased danger” for residents.

Traffic Danger

Accidents, sometimes fatal, do occur when police cars race to a crime scene with their sirens wailing. Once a driver hears the siren, his first instinct is to turn to the side of the road. But drivers may hear the siren and not see the police car, and their efforts to locate the police takes their eyes off the road, and into danger.

No Sleep

sirens wailing throughout the night, particularly in high crime urban areas, interfere with sleep, which produces stress and anxiety. Police in many cities, such some major cities in Nigeria, must follow strict guidelines when using their sirens when called to a crime.

1.7 SCOPE OF THE PROJECT

This siren simulated electronic project uses two 555 timers IC to generate a sound similar to the police siren. A single 556 timer IC which consists of two 555 timers can also be used. In this circuit, both of the timers are configured as astable circuit.

The first timer is configured as a square wave close to 1 Hz astable oscillator. The output of this timer is used to feed the control voltage of the second timer where it is subjected to frequency modulation. This frequency modulation will generate a tone similar to the siren. From the circuit, when the variable resistor is tuned, the siren will produce different sound.

1.8 APPLICATION OF THE PROJECT

Sirens are used on emergency service vehicles such as:

ambulances,
police cars,
Federal road safety corps,
fire trucks.
And other security personnel

1.9 METHODOLOGY

To achieve the aim and objectives of this work, the following are the steps involved:

Study of the previous work on the project so as to improve it efficiency.
Draw a block diagram.

Test for continuity of components and devices,

programming of microcontroller
Design and calculation for the changeover was carried out.
Studying of various component used in circuit.

Construct a digital changeover circuit.
Finally, the whole device was cased and final test was carried out.

1.10 PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to this project. In this chapter, the background, significance, objective limitation and problem of this project were discussed.

Chapter two is on literature review of this project. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.