Construction of a multi switch Musical doorbell with indicators

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CHAPTER ONE
1.0 INTRODUCTION
1.1 Introduction:

Modern doorbell, comes in two basic types, the simple electrical ding-dong (chims) or the sophisticated microprocessor – controlled multi-tune/switch (Rule Britannia etc) types. In either case, you pay your money and have to accept the sounds that the manufacturers have pre-programmed into your particular device. If you ever get tired of your bells limited range of sounds, you have little or no option but to buy a new unit.

We have decided to overcome this by designing a multi-switch musical doorbell with indicator as a project that will aid the owner to self-program the project to play any designed (but brief) melody. The essence of this project is that it is simple, and it is devoid of hard to get micros, PROMS, double sided PCBs etc yet gives an entertaining performance.
This doorbell is designed with six switches made up of a particular melody or tones. The melody continues as long as possible until the reset button is briefly operated.
A feature of this doorbell is that it incorporates a bistable electronic switch that connects power to the unit in such a way that it consumes virtually zero power when in standby mode, whenever the bell-button is pressed, the bistable connects power to the unit. For the duration of the tone play and automatically disconnects the power when the resets button is activated. This facility ensures long battery life.
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1.2 OBJECTIVES
The major purpose of a multi-switched musical doorbell with indicators which composes of different switches and a tone attached to it, helps in providing or creating of awareness to the occupant or residents of buildings, that their attention is needed at their door post. It is an electronic informer of building occupants.
And it also helps the owner or occupants of a building who have a multi-switch musical doorbell attached to their houses, for the easy recognition of the presence of a visitor in his or her house. The advantages of a musical doorbell are as follows:
- It allows an easy positioning of switch at different door steps of buildings i.e. for buildings that have more than one entrance.
- It goes beyond the reach of an ordinary knocking with bare-hands and also last as long as possible.
CHAPTER TWO
2.0 CIRCUIT COMPONENTS
2.1 List of Circuit Components
The following are the list of components that make up a multi-switch musical doorbell with indicators.
(a) Resistor
(b) Light Emitting Diode (LED)
(c) Capacitor 0.1μf
(d) Integrated Circuit (IC) CD4042B, CD4002
(e) Transistor SL100B
(f) Push to on switches
(g) B21 Musical Buzzer (6 – 12v dc)
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2.2 INTEGRATED CIRCUIT
An integrated circuit (IC) is a tiny piece of semi-conducting material into which a very complex circuit is cut. It is a complete circuit manufactured in a single package i.e. many circuit contain in one package. They are different types of integrated circuits (ICs). On like in the hybrid IC, separate components ends / or circuit are attached to a ceramic substance and interconnected.
In monolithic ICs, all the components are manufactured into or on top of a single chip of silicon. They are formed by selective diffusion of the appropriate type of impurity into a layer of semiconductor. The bipolar junction transistors and the MOS, ICs are based on insulated gate field effect transistor. Both are lythic circuits.
They are several types of IC in use today. Those used for the surface mount technology are the plastic guard flat package. The flat pack (glass/metal). Other ICs used with sockets are the pin grid array package (PGA) and the leadless package.
Those ICs like the TO-3, TO-220 packs and TO-066 are used for voltage regulators, others are the TO-5 package, which are available with 8,10, and 12 pins. (TO-39, TO-96, TO-99 and TO-100). The dual in like package (DIP) is popular. It may have 14 or 16 pins. The main – DIP is a shorter version of the dual in line package, it has 8 pins.
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CIRCUIT SYMBOL
The main IC used for this project work are the CD4042B and CD4002B types.
2.3 RESISTOR
A resistor is an electrical component that offers opposition to the flow of current in circuit. They are described by stating their resistance in ohms along with their safe power dissipating ability in watt. Resistors may be classified avoiding their constitution which may be composition film types or wire wound, further classification may be made according to whether the resistor is fixed or variable. Variable may be further classified as variable – slide rheostat and potential types.
The resistance value and tolerance are indicated on the resistor body by means of colour code bond (especially in carbon filled type). In practical, factors to be considered in the choice of a resistor for a given purpose are:-
i. Required resistance
ii. Power to be dissipated (I2R) or current to be carried.
iii. Effect of residual (inherent) inductance and capacitances.
iv. Allowable tolerable (deviation from labelled ‘normal’ resistance) value.
v. Effect of variation of resistance with temperature
Red
Red
Red
Gold
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2.4 LIGHT EMITTING DIODE (LED)
It’s a special P-N Junction diode that emits light when forward-biased. When a normal diode is forward-biased, current flows which cause a voltage drop of approximately 0.7 volts in a silicon diode. The voltage drop times the magnitude of current flow results in power dissipation at the junction. In a normal diode, this power is dissipated in the form of heat energy. However, in the case of a light emitting diode, this power is dissipated in the form of light.
There are two main differences between normal diodes and LED. One difference is that LED’s are made from gallium arsenide (Ga/As). Gallium arsenide phosphide (Ga,As,P) or gallium phosphate (Ga,P) diodes manufactured from these elements radiates visible light energy when forward-biased. The second difference is that LEDs are so designed as to have a window over the unction so that light energy can be seen.
The different wavelengths of light emitted by the above LED are as under:
i) Ga,AS - 8800A0 infrared radiation
ii) Ga,P - 5500A0 (green) or 7000A (red)
iii) Ga,As,P - 5800A0 (amber) or 6600A (red)
LED are commonly used for indicator lamps and read out displays device using LED from consumer appliances to scientific apparatus. A very common type of display device using LED is the seven segment display shown below
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SEVEN SEGMENT DISPLAY
Combination of these segments can form the ten decimal digits. Infrared emitting LEDs are used in optical coupling applications often in conjunction with fibre optics.
Light Energy
P
N
SYMBOL OF DIODE
LED
2.5 CAPACITOR
A capacitor essentially consists of two conducting surfaces separated by a layer of an insulating medium called dielectric. The
conducting surfaces may be in the form of either circular (or rectangular) plates or of spherical or cylindrical shape. The purpose of a capacitor is to store electrical energy by electrostatic stress in the dielectric.
Therefore, the electrolytic capacitors are either the wet type or dry type. The wet type consists of an aluminum anode which is centrally mounted in a metal cylinder filled with an electrolytic solution usually ammonium borate which acts as a cathode. Two connections, one
+
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from the anode and the other from the cathode are brought out. When current is passed between the anode and cathode, a very thin film of aluminum oxide (Al2, 03) is formed on the anode surface. This film has insulating properties and the anode – cathode combination, thereafter becomes a capacitor of very large capacitance because dielectric film is extremely thin. For successful operation, such capacitors must always be used with proper polarity. The dry type capacitor consists of positive and negative electrodes of aluminum foil which are separated from each other by a porous paper or guaze saturated with either a very viscous liquid or paste containing the electrolyte. The whole arrangement is formed into a roll and housed in a waxed cardboard tube. Due to their high capacitance, such capacitors are used generally in smoothing circuit in radio work.
Capacitor Symbol
2.6 TRANSISTOR
Basically, it consists of two back-to-back P-N junctions manufactured in a single piece of a semi-conductor crystal. These two junctions give rise to three regions called emitter, base, and collector. A junction transistor is simply a sandwich of one type of semiconductor material between two layers of the other type, a layer of N-type material sandwich between two layers of P-type material, it is described as PNP transistor.
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Structure
C E
E C
B
B SYMBOL
The NPN transistor consists of P-Type material sandwich between two layers of N-type material. The emitter, base and collector are provided with terminals which are labeled as E, B and C. the two junctions are: emitter base (E/B) Junction and Collector Base (C/B) junction.
Structure
E C
B
The arrowhead of transistor is always at the emitter (not at the collector) and in each case, its direction indicates the convectional flow of currents. For a PNP transistor, the arrowhead points from emitter to base meaning that emitter is positive with respect to base (and also with respect to collector). For an NPN transistor, it points from base to emitter meaning that base (and collector as well) is positive with respect to emitter.
EMITTER
It forms the left hand section or region of the transistor, it is more heavily doped than any of the other regions because it’s main
P
N
P
N
P
N
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function to supply majority charge carriers (either electrons or holes) to the base.
BASE
It forms the middle section of the transistor. It is very thin (10-6m) as compared to either the emitter or collector and is very lightly doped.
COLLECTOR
It forms the right hand side section or region of the transistor and its main function is (as indicated by its name) to collect majority charge carriers coming from the emitter and passing through the base.
In most transistors, collector region is made physically larger than the emitter region because it has to dissipate much greater power, it may be noted, in passing, that transistors are made by growing, allowing or diffusing processes.
CHARACTERISTICS
These are the curves which represent relationships between different dc currents and voltages of a transistor. These are helpful in studying the operations of a transistor when connected in a circuit. The three important characteristics of a transistor are:
1. Input characteristics
2. Output characteristics
3. Constant-current transfer characteristic.
2.7 MUSICAL BUZZER (6 – 12V DC)
Musical buzzer in these project helps in bringing out quality output from the input when the various switches are operated, and these output comes in the form of melody. The multi-switched musical
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doorbell with indicators makes use of a 6 – 12v dc. A musical buzzer possesses some similar characteristic related to an ordinary radio speaker.
+
_
Circuit Symbol
2.8 PUSH – TO – ON – SWITCH
The type of switch used for the proper execution of this project is the push-to-on switches which are readily available, on like every other electronic switches used in some electronic components, and its operation is based on the push to on mode for activating the system, until the reset button is pressed.
2.9 VERO BOARD:
Vero board is a matrix board with continuous copper ship attached to one side by adhesives. The copper strip link together rows of holes so that connections can be made between components inserted into holes on a particular row. The circuit components are held permanently on the vero board with the use of a soldering iron and lead.
CHAPTER THREE
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3.0 CONSTRUCTION OF MULTI-SWITCH MUSICAL DOORBELL WITH INDICATORS
3.1 BLOCK DIAGRAM
C Buzzer
3.2 SCHEMATIC DIAGRAM
RESET
SWITCH S5
S2 – S4 SWITCHES
R6 – R9 RESISTORS
DC POWER SUPPLY UNIT +9V
R1 – R5
RESISTORS
LEDS
IC1
N1&N2
IC2(GATES)
TRANSISTOR
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3.3 HOW IT WORKS
In the circuit of a multi-switch input musical doorbell, the circuit is built around the popular and less expensive guard D-latch CD4042B (IC). When switch S6 is pushed to ‘on’ condition, the circuit gets +9v and the four data inputs (D1 through D4) of IC1 are in low state because these are tied to ground via resistors R1 through R4. Polarity input (POL) Pin 6 of IC1 is also pulled down by resistor R5. Clock input (Pin5) of the guard D-latch is wired in normally low mode
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and hence all the four outputs (Q0 through Q3) have the same states as their corresponding data inputs. As a result, LED1 through LED4 are in off condition.
There are four switches fitted at four different doors/gates outside the home and a monitoring panel in the common room of the home. If any switch is pressed by a visitor (for example switch S1 at door 1), pin2 and 4 of IC1 go high. Simultaneously, pin 3 to IC1 (Qo output) goes low and LED1 starts glowing to indicates that switch S1 is pressed by someone.
Next output pin 13 of the dual 4-input NOR gate (IC2, here wired as a single 4-input OR gate) goes high to forward bias buzzer driver transistor T1 via resistor R10.
The final result is a soft and pleasing musical bell, which lasts until reset switch S5 is pressed by the owner. For this latching arrangement, output pin 13 of IC2 from the NOR gate is fed back to the clock input of IC1.
CHAPTER FOUR
4.0 TOOLS AND CONSTRUCTION TECHNIQUES
4.1 CONSTRUCTION TECHNIQUES
The construction of this project is a simple but, lightly complicated and technical one. In the construction of the main circuit board the following steps were followed.
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- The strip (vero) board was marked with strips running from left to right.
- The components were assembled taking care to fix in the transistor, diode etc. the right way round. The integrated circuits (ICs) were mounted and positioned in such away that, the current pins stay in the correct holes.
- Correct soldering of components was done to ensure good electrical and mechanical constant.
- Connectors were often used to carry/connect terminals from the strip board to the external components like the switch, LED etc.
- Finally, the strip board was fixed inside a case, care was taken to ensure that the board was properly fixed into the base of the case and that no metallic object was bringing any of the strip board lines.
The container was designed to ensure that the strip board and other components sit inside comfortably, and that no element of the case was disturbing the comfort of the others.
The case material was cut out, designed and the finished was polished before the case design are
- The size
- The shape
- The accessibility to the internal component in time maintenance.
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Finally, the cover of the case was screwed in, to give a complete and perfect finished job.
4.2 TOOLS/MATERIALS USED FOR CONSTRUCTION
In the course of constructing this project, various tools/material were used to ensure proper connection of wires and fillings of components at their appropriate positions in order to achieve a successful result. Base on this, the following tool/materials were used:
- Side Cutter:- This was used for cutting off the remaining of the soldering.
- Long Nose Pliers: It was used for picking materials from places where bear hand cannot be able to reach. It was also used for holding components before soldering thereby acting as temporary heat sink to such components.
- Solder: This is a soft silver metal made of two materials, an allow of tin and lead. There are three main grades of solder, 40-60 grades, 50-50 grades. The first figure is the percentage of tin while the second is the percentage of lead. The 60-40 grades are popularly employed for electronic work but more expensive.
- Combination Pliers: This was used for griping and cutting of wires with other cylindrical material and also for loosening nuts.
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- Soldering Iron: In the construction of this project, two types of soldering irons were used. These are: the electric iron and the fire soldering iron. The electric type has a cord through which electric passes into it to be heated up while the fire type can be heated by merely placing it on the fire.
4.3 TESTING
After the construction, the system was tested and there rang almost to the number of time expected, so for that reason some components in the circuit were adjusted while some were replaced to improve the system performance. The power supply unit was tested again for over two hours to ascertain it normal ringing level of the various bell controlled by the switches.
CHAPTER FIVE
5.0 SUMMARY, CONCLUSION AND RECOMMENDATION
5.1 SUMMARY
In summary, the construction of a multi-switch musical door bell with indicators was carried out successfully and the circuit components well soldered to their various positions and firmly to the vero board, in order for a melodious output through the buzzer, when operated through the various switches, which are made to be positioned in visible parts of building entrance.
5.2 CONCLUSION
The aim of carrying out a project is to make the students adopt the theories into the practical realization for the benefits of man kind. The construction of a multi switch musical doorbell with indicators consist of
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various components into connected in a systematic manner that the bell brings out a reliable output in the form of sound signal through the buzzer. In conclusion, I wish to state here that, in any construction, it is not an easy assignment among others: time, planning, reading, research, modifications, and challenges to cope with.
5.3 RECOMMENDATIONS
This project work has it’s limitations among which are time factor, technical specification and finance. These areas should be looked into for improvement in subsequent work on the same topic through the following points or areas.
1. Project Writing and Construction should be taught with much emphasis laid on the requirements needed.
2. Government and industries/industrial training fund should contribute fifty percent of the project development. This will make the products to be of quality to compete in the market.
3. The project as a course should be weighted the same as such courses like electronics, telecommunications, electrical power, circuit theory and machines etc, so that the graduates will be more serious on it than now.
REFERENCES
B.L. Thereja Electrical Technology Vol. 1
A.K. Thereja
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Donald E. Scott Introduction to Circuit Analysis & System Approach
Glence Mc Gan-Hill Electronic Principle (Sixth Edition)
Boylestad Nashelsky Electronic device and Circuit Theory
(7th Edition)
Hughes Electrical/Electronics Technology
(8th Edition)