1.0 INTRODUCTION

A doorbell is a signaling device typically placed near an entry door to a building. When a visitor presses a button the bell rings inside the building, alerting the occupant to the presence of the visitor. Although the first doorbells were mechanical, activated by pulling a cord, modern doorbells are electric — they are actuated by an electric switch.

However, this work is wireless doorbell which is the modification of wired doorbell. 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 such as Westminster Quarters. 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 telephone 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 signalling.

A typical wireless doorbell system generally comprises at least one RF transmitter powered by a battery or other power source, such as existing electrical wiring, and a RF receiver. In response to the depression of a button or other activating means on the transmitter, an electrical circuit is completed within the transmitter which energizes an oscillator or other means for generating a RF signal. The generated RF signal is then, with the aid of an antenna, transmitted a certain distance for reception by the receiver. The receiver alerts, for example, a homeowner that the doorbell button has been depressed by producing an audible signal, such as a tone or melody, upon detecting the transmitted RF signal.

1.1 BACKGROUND OF THE PROJECT

Today the traditional wired type of doorbells are gradually getting obsolete and are being replaced by the advanced wireless type of doorbells that are easier to install due to their hassle free set-ups.

Wireless doorbell systems have become an increasingly popular option for persons wishing either to replace their current doorbell system or to add additional doorbells at their place of business or residence. A typical wireless doorbell system generally comprises at least one RF transmitter powered by a battery or other power source, such as existing electrical wiring, and a RF receiver. In response to the depression of a button or other activating means on the transmitter, an electrical circuit is completed within the transmitter which energizes an oscillator or other means for generating a RF signal. The generated RF signal is then, with the aid of an antenna, transmitted a certain distance for reception by the receiver. The receiver alerts, for example, a homeowner that the doorbell button has been depressed by producing an audible signal, such as a tone or melody, upon detecting the transmitted RF signal.

1.2 PROBLEM STATEMENT

Conventionally, door bell is activated once the visitor approaches the door of the host by making contact / pressing the switch at the door, and this gives the visitor stress when locating the switch most especially at night when everywhere is covered with darkness. However, this device came into existence to overcome the problem of searching for the switch before a door alarm is rung. This device rings an alarm once the visitor approaches the door from a set distance using RF signal.

1.3 OBJECTIVE OF THE PROJECT

When a visitor presses a button the bell rings inside the building, alerting the occupant to the presence of the visitor.

1.4 SCOPE OF THE PROJECT

Wireless doorbell systems which employ radio frequency (“RF”) transmitters and receivers. Both the transmitter and receiver is powered batteries or other power source, such as existing electrical wiring. The wireless transmitter, comprising a power source; a metal case divided into two or more electrically isolated sections by one or more electrically non-conductive gaps there between; a means disposed within said metal case for closing an electric circuit; an antenna enclosed within said metal case; a means for generating a radio frequency signal enclosed within said metal case; and an electric circuit connected to said power source, said means for closing said electric circuit, said antenna and said means for generating a radio frequency signal; wherein said means for generating a radio frequency signal is energized by said power source and a radio frequency signal is produced when said means for closing an electric circuit is moved to a position which closes said electric circuit. 

1.5 SIGNIFICANCE OF THE PROJECT

A wireless doorbell does not have wires that hassle the installation. Installation is now simple. Installing the wireless doorbell is as easy as removing the installed wired doorbell and putting on batteries on the wireless doorbell and placing it to its location. Also, the wireless doorbell is portable; it can be moved wherever the homeowners like it to be placed. This would be very helpful for future remodeling or refurnishing of the house. Wireless doorbell is more versatile over Wired Doorbell.

1.6 LIMITATION/ PROBLEM OF THE PROJECT

There are so many hindrances in installing wired doorbell that are surpassed by wireless doorbell. Wireless doorbell can be placed in places where wired doorbell cannot reach. Also, wireless doorbell is efficient and more suitable on apartment and rented homes. This is because, when the one who rents the house or apartment is going to transfer, he/she can take the wireless doorbell and place it on his/her new rented/leased house.  

Signal interference is a problem on wireless doorbell. For cheaper wireless doorbell, when triggered by some wireless device, the wireless doorbell will not work which sometimes cause malfunctioning of the device. Interference like car alarms, garage door opener, or other wireless doorbell may cause malfunction of your cheap wireless doorbell. However, regular or higher end wireless doorbell has multiple frequencies which allow blocking out of signal interferences.

1.7 APPLICATION OF THE PROJECT

The main purpose of using this device in any place is for alertness. This device can be used in the following places:

1. Homes

2. Church

3. Offices

4. Industries, etc.

1.8 METHODOLOGY

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

i. Study of the previous work on the project so as to improve it efficiency.

ii. Draw a block diagram.

iii. Test for continuity of components and devices, 

iv. Design and calculation for the device was carried out.

v. Studying of various component used in circuit.

vi. Construction of the circuit was carried out.

vii. Finally, the whole device was cased and final test was carried out.

1.9 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 the study. In this chapter, the background, significance, application, objective limitation and problem of the study were discussed.

Chapter two is on literature review of this study. 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.