LIST OF FIGURES

Fig. 2.1 PIR model D204B                                                                                                     10

Fig. 2.2 LM358 inter-grate circuit                                                                                          12

Fig 2.3 Pin out of IC or LM 358                                                                                            12

Fig 2.4BJT and JFET symbols                                                                                                14

Fig 2.5 Diode schematic symbol                                                                                             15

Fig 2.6 LM78XX voltage regulator                                                                                        18

Fig. 2.7 Electronic symbol of a Buzzer                                                                                   19

Fig 3.1 Block diagram of automatic doorbell                                                                         21

Fig 3.2 Circuit diagram of automatic doorbell                                                                       22

Fig 3.3 power supply circuit                                                                                                   22

Fig 3.4 circuit diagram of power supply                                                                                 24

Fig 3.5 circuit calculation of power indicator light emitting diode (LED)                             29

LIST OF SYMBOLS AND ABBREVIATIONS

Symbol                                            Name                                                     Abbreviation

TRANSFORMER                                                      T

Diode                                                              D

                                      Resistor                                                                     R                    

 Capacitor                                                                    C

                   E

Transistor

C

Buzzer

Operational Amplifier                                                 OPAMP

ABSTRACT

This project deal with the design and construction of a door bell using PIR sensor. The presence of wireless technology in the world today has improved the capability and functions of security and home automation products. Nobody could complain about the wireless capability because the elimination of wires and complicated set up procedures make these devices easy to control and customize. Wireless doorbells are visitor alerting systems that are usually involve a push button and a wireless door chime. This is a handy setup because once the push button is pressed, it transmits a signal to the door chime, which is the receiver. The door chime emits a sound or light usually chosen by the user, to indicate that there are visitors. This project seek to improve on the existing wireless doorbell design by incorporating a motion detector to replace the door push button, thus, the circuit is activated when a visitor sensed at the door or gate via the PIR. This technology innovation has made it possible to activate doorbells without touching any mechanical switch. This project was tested and was found to operate as required.

CHAPTER ONE

INTRODUCTION

1.1       Background of the Study

A doorbell is a signaling device commonly found near a door. There basically used to call attention to the door, i.e. to signal that someone is at the door and needs attention. Traditionally, knocking (hitting) the door with the hand serves as a means of signal calling attention to the entrance to a building. However, with the invention of electricity, different forms of passing current through mechanical switches to sound generating device have replaced the ancient method.

The doorbell has come a long way, William Murdoch, a Scottish inventor, installed a number of his own innovations in his house, built in Birmingham in 1817; one of these was a loud doorbell, that worked using a piped system of compressed air. A precursor to the electric doorbell, specifically a bell that could be rung at a distance via an electric wire, was invented by Joseph Henry around 1831. By the early 1900s, electric doorbells had become commonplace.

Modern doorbell could be classified into wired and wireless type. In most wired systems, a button, located around the height of the doorknob, activates a signaling device (usually a chime, bell, or buzzer) inside the building. Most signaling devices consist of two solenoids and two flat bars. The flat bars are tuned to two pleasing notes. The flat bars are mounted loosely above and below the solenoids. When the doorbell button is pressed, the first solenoid's plunger strikes the bottom bar. When the button is released, a spring on the plunger pushes the plunger up, causing it to strike the other bar. If the other bell is used, it will activate the other solenoid, which will strike only one bar — typically the bottom bar. More elaborate signaling devices play a short musical electronic tune.

In recent decades, wireless doorbell systems that do not require wall wiring have become popular. The doorbell button contains a built-in radio transmitter powered by a battery. When the button is pushed, the transmitter sends a radio signal to the receiver unit, which is plugged into a wall outlet inside the building. When the radio signal is detected by the receiver, it activates a sound chip that plays the sound of gongs through a loudspeaker—either a two-note "ding-dong" sound or a longer chime sequence. To avoid interference by nearby wireless doorbells on the same radio frequency, the units can usually be set by the owner to different radio channels.

In larger metropolitan cities, a trend has developed over the past decade that uses elephone technology to wirelessly signal doorbells as well as to answer the doors and remotely release electric strikes. In many cities throughout the world, this is the predominant form of doorbell signaling.

1.2       Aim and Objective

This project seek to improve on the existing wired doorbell by incorporating a motion detector. Technological innovation has made it possible to activate door bells without touching any mechanical switch. These systems are mostly activated by light, infrared beam, sound etc. the aim of this project thus, is to design and implement an infrared based automatic door bell.

1.3       Methodology

Contemporary sensor-based automatic door technologies include infrared, ultrasonic/radio, or other wireless sensing methods. The first can be further divided into active and passive approaches.

The active process emits infrared signals from the controller and captures the reflected signals to determine if there is any object close to the door. This approach is accurate and capable of identifying the position and the speed of the object but its high cost has made it less popular. The ultrasonic/radio approach, on the other hand, emits ultrasonic or radio waves to scan the environment and analyzes the returned signals for door circuit. The passive IR approach detects the infrared signals radiated by people and is the most widely used for being simple, effective, and low cost. This project uses this approach. A PIR detects image and an electrical signal is generated and activates an alarm circuit.

1.4     Scope of Study

This project work covers;

- The design and construction of image detector circuit

-design and construction of an audio signaling circuit

             - integration of the aforementioned units

- testing and evaluation of the system

1.5       Project Outline

This report is outlined in the following format: chapter one contains the introduction, chapter two; the review of related materials, chapter three; the circiut diagram, block diagram and design analysis, chapter four; the construction and testing details,, and, chapter five contains the conclusion, recommendations and references.

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